**[MEMORANDUM]{.underline}**

**[Reclassification Petition: Clinical Consult Review]{.underline}**

**To: Orthopaedic Advisory Panel**

**From: Orthopaedic Devices Branch, Division of General, Restorative and
Neurological Devices;**

**Date: April 26, 2004**

**Subject: Reclassification Petition: Mobile Bearing Knee Prostheses**

**\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_**

[**Summary:**]{.underline}

This reclassification petition presents data to support the petition for
reclassification of all mobile bearing unicondylar, bicondylar condylar
and tricompartmental knees from Class III to Class II. This includes
clinical data from IDE and outcome studies, peer reviewed journal
articles and meta- analysis comparison analyses between fixed and mobile
bearing systems related to adverse events and effectiveness outcomes.
The sponsor believes that this information provides strong evidence of
the safety and efficacy of mobile bearing knees, and that the risks
associated with these devices are now adequately defined. Before a
decision can be made whether reclassification from Class III (Premarket
Approval Application) to Class II (Special Controls) is justified,
further information and clarification is needed.

**[Background:]{.underline}**

Reclassification is requested from Class [III]{.underline} to Class
[II.]{.underline}

There are numerous mobile bearing knee designs on the market worldwide

designed to increase contact area and /or to reduce implant-to-bone
interface stresses by allowing mobility of the polyethylene bearing on
the tibial plate in order to potentially reduce long-term wear.

**[Regulatory History of the Device Class]{.underline}**

FDA issued a Proposed Rule classifying 77 orthopedic devices on July 2,
1982 (47 FR 29052), and the Final Rule on September 4, 1987 (52 FR
33686). The Final Rule established twelve separate categories of
implantable knee prostheses (21 CFR 888.3480 through 888.3590). Each of
the twelve types of knee prostheses described were assigned to either
Class II or Class III depending on system attributes such as fixation
method, level of constraint, and degree of resurfacing (e.g.,
patellofemorotibial versus femoral).

None of the categories, however, describes the type of total knee
replacement system that has come to be known as the mobile bearing knee.

The question of reclassification of mobile bearing knees from Class III
(Premarket Approval) to Class II (Special Controls) was considered by an
FDA Advisory Committee on January 13, 1998. At that time, the panel\'s
recommendation was to retain the Class III designation for all
tricompartmental and unicompartmental mobile bearing knees with the
exception of recommending reclassification of tricompartmental mobile
bearing knees

that are cemented and have a rotating/translating base. The panel also
recommended post-market surveillance for those mobile bearing knees
reclassified to Class II. The FDA subsequently chose to recommend
submission of a new reclassification petition for the entire class of
mobile bearing knees, rather than reclassify specific subcategories.

**[Device History]{.underline}**

The first mobile bearing knee designs were introduced in the late
1970\'s. The Oxford Unicondylar knee (Biomet, Inc., Warsaw, IN) was the
first to utilize a mobile bearing to reduce contact stress while also
reducing implant-to-bone interface stress. Since those early implants,
several generations of mobile bearing knees have followed, and today
there are nearly 50 unicondylar and bi-condylar implant designs with
either platform-style or meniscal bearing design of the polyethylene
articulating surface on the international market. There are numerous
variations in the directional mobility of the polyethylene, type of
constraint of the polyethylene, and treatment of the PCL. The first
mobile bearing knee to be approved by the FDA for sale in the U.S. was
the Low Contact Stress (LCS) Rotating Platform Knee (J&J DePuy, Warsaw,
IN). PMA approval for this knee was received in 1985, and since then
five other mobile bearing knees have been approved in the U.S.

Reclassification of several types of knees from Class III to Class II
was considered by an FDA Advisory Panel on January 13, 1998 (\"Petition
for Reclassification, Patello-Femoral-Tibial
Metal/Polymer/Metal/Polymer/Metal Biologically Fixed Prosthesis,
submitted by the Orthopedic Surgical Manufacturers Association, July 25,
1997). Mobile bearing knees were included in that petition. At that
time, the Panel believed there was insufficient evidence to provide
reasonable assurance of safety and efficacy for the entire class of
mobile bearing knees. They recommended reclassification only of
tricompartmental mobile bearing knees that are cemented and have a
rotating/translating base. However, they recommended the retention of
Class III designation for all other tricompartmental and
unicompartmental mobile bearing knees.

At this time 6 devices are available in the US:

• Low Contact Stress (LCS) Rotating Platform

• P.F.C. Sigma Rotating Platform

• P.F.C. Sigma Stabilized Rotating Platform

• Low Contact Stress (LCS) Meniscal Bearing

• Low Contact Stress (LCS) Unicompartmental Knee

• Oxford Meniscal Unicompartmental Knee

**[Intended Use:]{.underline}**

The intended use differs depending on the subtype.

The mobile bearing total knee, fixed with or without bone cement is
indicated for:

> • Patients with knee pain and disability due to rheumatoid arthritis,
> osteoarthritis, traumatic arthritis, polyarthritis, collagen disorders
> and/or avascular necrosis of the femoral condyle
>
> • Post-traumatic loss of joint configuration (particularly when there
> is patellofemoral erosion, dysfunction, or prior patellectomy)
>
> • Moderate valgus, varus, or flexion deformities
>
> • The salvage of previously failed surgical attempts if the knee can
> be satisfactorily balanced and stabilized at the time of surgery

The mobile bearing unicompartmental Knee, fixed with or without bone
cement is indicated for:

• Patients with knee pain and disability due to osteoarthritis or
traumatic arthritis

• Previous tibial condyle or plateau fractures with loss of anatomy or
function

• Varus or valgus deformities

• Use with an intact Anterior Cruciate Ligament (ACL)

• Revision of previous unicompartmental arthroplasty procedures

**[Device Description/Principle of Operation:]{.underline}**

This class of devices includes two subtypes: bicondylar knee joint
patellofemorotibial metal/polymer mobile bearing cemented or porous
coated uncemented prosthesis\" and

Unicondylar knee joint femorotibial (uni-compartmental) metal/polymer
mobile bearing

cemented or porous coated uncemented prosthesis\"

The defining feature of a mobile bearing knee is the presence of a
[moving]{.underline} polyethylene bearing that articulates with both the
femoral condyle and the tibial tray. It is theorized that mobile bearing
knee designs potentially reduce polyethylene wear by their highly
conforming surface that disperses contact forces over a large area. The
mobility in the polyethylene bearing, which reduces implant-to-bone
interface stresses, may prevent implant loosening, which has been
attributed to high interface stresses in highly conforming fixed bearing
knee designs.

Mobile bearing knees are available in PCL-retaining, PCL-sacrificing and
PCL stabilizing designs. In general, knees with only rotating mobility
utilize a PCL sacrificing or PCL-stabilizing design, while
multidirectional platform knees generally are PCL-retaining.

These devices can be further categorized by the type of bearing surface
(Platform, bicondylar meniscal bearing, and unicondylar meniscal
bearing), type of constraint and type of fixation (cemented , porous
coated uncemented).

[Bearing Surface]{.underline} included:

-   [Platform]{.underline}: a single polyethylene bearing that rotates
    in the transverse plane, with or without A/P motion (rotating only
    or multidirectional).

-   [Meniscal Bearing]{.underline}: separate medial and lateral
    polyethylene bearings that slide

> independently in arced tracks that run anteriorly and posteriorly in
> the fixed, metal

tibial component

-   [Unicondylar Meniscal Bearing]{.underline}: an implant in which only
    the medial or lateral

> compartment of the knee is replaced. The polyethylene may run in a
> track as
>
> described above, or may move freely, held in place only by its
> reciprocal shape and
>
> the tension of the surrounding ligaments.

Past experience and literature have shown that the use of cement has
improved results and higher failure rates are associated with non
cemented use. In light of this information, it should be considered
whether we can include uncemented (porous coated) devices with cemented
devices (i.e. do we have enough data to feel comfortable that special
controls will predict safe use).

[Type of Constraint]{.underline} (prevention of bearing dislocation)

Unconstrained designs have very low constraint forces over the entire
range of normal (physiologic) displacements.

Semi-constrained designs have near physiologic constraint that rises
over the range of normal displacements.

Constrained designs have constraint forces that exceed physiologic
levels and rise sharply over the range of displacements

-   Cone-in-cone Design: incorporates a tapered projection of the
    polyethylene insert that inserts into a reciprocal concavity in the
    tibial tray

-   Tibial Tray Post**:** A post extending from the superior surface of
    the tibial tray fits into a recess on the polyethylene insert

-   Longitudinal Curved Sliding Tracks**:** Movement of the platform or
    meniscus is limited by a track formed in the upper surface of the
    tibial tray

-   Stops: elevated rim of the tibial tray that limits excessive A/P
    translation or rotation

-   Unconstrained Bearing: designs that lack a mechanical limit to
    movement, but instead rely on the conformity of the polyethylene
    mobile bearing to the femoral condyle and the tension of the soft
    tissues

[Characterization of the Directional Mobility of the Bearing
Surfaces:]{.underline}

Nine knee designs were tested in a dynamic testing system in which
compressive load was applied as the knee was rotated or moved in the A/P
or M/L direction. Torque or shear forces were measured and plotted
against displacement, thus characterizing the ability of the knee design
to constrain displacement during gait. The nine designs were then
characterized as \"unconstrained\", \"semiconstrained\", and
\"constrained\". Of the nine designs evaluated, all demonstrated
unconstrained motion in the rotational direction and all the mobile
bearing designs

demonstrated unconstrained mobility within a total of 15 degrees
internal/external rotation. Relative to M/L mobility, the designs tested
were evenly divided between semi-constrained and constrained mobility.
Constrained and semiconstrained M/L mobility is characteristic of both
mobile and fixed bearing knee designs, and does not adversely affect
clinical performance. Analysis of A/P mobility revealed a wide range of
constraint, with unconstrained designs prevailing. In order to achieve
joint stability with the lower level of constraint, competent soft
tissue, including balanced collaterals and/or the PCL are necessary.

• Congruence:

Fully congruent mobile bearing knees are those that have a high degree
of conformity between the femoral condyle and the polyethylene bearing
surface, over a wide range of flexion (approximately 120 degrees).
accomplished by providing a constant sagittal femoral radius, limited by
posterior impingement of the tibial component**.** A fully congruent
prostheses has a large contact area between the femoral condyle and the
bearing surface, disperses contact forces, thereby theoretically
resulting in reduced polyethylene wear.

[Gait congruent or partially congruent]{.underline} mobile bearing knees
have large contact areas in the first 20 degrees of flexion. The contact
area decreases with flexion due to a decreasing sagittal radius. These
prostheses maximize contact areas in the low end of the flexion range,
while decreasing the sagittal radius to improve flexion range.

The term \"functionally congruent" is used to mean that a device has a
single femoral radius for up to 75 degrees of flexion.

**[Summary of Unpublished IDE data]{.underline}**

+------+--------+--------+--------+--------+--------+--------+--------+
|      | **BI   | **OX   | *      | **PR   | **STR  | **ZI   | **ZI   |
|      | OMET** | FORD** | *S&N** | OFIX** | YKER** | MMER** | MMER** |
|      |        |        |        |        |        |        |        |
|      | **TRAC | **U    | **GEN  | **RP** | **HO   | **     | N      |
|      | PS**   | NICOND | II**   |        | S      | MOBILE | EXTGEN |
|      |        | Phase  |        | **MP** | CORPIO | BEA    |        |
|      | **Rota | II**   | **Ro   |        | PS**   | RING** | **LPS  |
|      | ting** |        | tating |        |        |        | FLEX** |
|      |        | **Me   | P,**   |        | **RP** | **K    |        |
|      | **Plat | niscal |        |        |        | NEES** | **RP** |
|      | form** | Bea    | **Mult |        |        |        |        |
|      |        | ring** | idirec |        |        | **MP** |        |
|      |        |        | tional |        |        |        |        |
|      |        |        | P**    |        |        |        |        |
+------+--------+--------+--------+--------+--------+--------+--------+
| **Ty | P, MC, | P,MC   | P,MC,R | P,MC,R | P,MC,R | P,MC,  | P,MC,R |
| pe** | Rand   |        |        |        |        | NR     |        |
+------+--------+--------+--------+--------+--------+--------+--------+
| *    | 130    | 125    | 1      | 59     | 62     | 179    | 61ce   |
| *#en | (all   | kne    | 09/119 |        |        |        | mented |
| roll | cem    | es(all | ce     | 50     |        |        |        |
| ed** | ented) | cem    | mented | cement |        |        |        |
|      |        | ented) |        |        |        |        |        |
|      |        |        | 94/10  | 9      |        |        |        |
|      |        | 107    | 4knees | hybrid |        |        |        |
|      |        | pts    | unce   |        |        |        |        |
|      |        |        | mented |        |        |        |        |
|      |        |        |        |        |        |        |        |
|      |        |        | 15     |        |        |        |        |
|      |        |        | hybrid |        |        |        |        |
+------+--------+--------+--------+--------+--------+--------+--------+
| **1  | 103    | 1      | 106 pt |        | 41 pts | 145    | 81/12  |
| yr** |        | 04/125 |        |        | @ 7    |        | 3(65%) |
|      |        |        |        |        | weeks; |        |        |
|      |        |        |        |        | (6 mo  |        |        |
|      |        |        |        |        | 12pts) |        |        |
+------+--------+--------+--------+--------+--------+--------+--------+
| **2  | 89     |        | 3      |        |        | 51%    |        |
| yr   |        |        |        |        |        |        |        |
| (    |        |        |        |        |        |        |        |
| %)** |        |        |        |        |        |        |        |
+------+--------+--------+--------+--------+--------+--------+--------+
| **3  | 333    |        |        |        |        |        |        |
| yr** |        |        |        |        |        |        |        |
+------+--------+--------+--------+--------+--------+--------+--------+
| **4  | 6      |        |        |        |        |        |        |
| yr   |        |        |        |        |        |        |        |
| f    |        |        |        |        |        |        |        |
| /u** |        |        |        |        |        |        |        |
+------+--------+--------+--------+--------+--------+--------+--------+
| **   | 2.2 yr | 4.8    | 1 yr   | 9 mo   | 3 mo   | 1.5 yr |        |
| Mean |        |        |        |        |        |        |        |
| F    |        |        |        |        |        |        |        |
| /U** |        |        |        |        |        |        |        |
+------+--------+--------+--------+--------+--------+--------+--------+
| *    | 65     | 62     | 64-65  | 64     | 63     | 65     | 62     |
| *Age | (      | (      |        |        |        |        |        |
| Me   | 40-87) | 34-85) |        |        |        |        |        |
| an** |        |        |        |        |        |        |        |
+------+--------+--------+--------+--------+--------+--------+--------+
| **K  | KSS    | HSS    | 89=    | KSS    | 75%    | KSS    | KSS    |
| SS/H |        |        | ave    | 92%    | 6mo    | 89.7   | 84%    |
| SS** | 1 yr   | 95.2   | KSS    |        |        |        |        |
|      | 77.4%  |        |        |        |        | 89.3   |        |
| **   |        | 95     |        |        |        |        |        |
| Good | 2 yr   |        |        |        |        |        |        |
| -Exc | 83.7%  | 14%    |        |        |        |        |        |
| elle |        | re     |        |        |        |        |        |
| nt** | 3 yr   | quired |        |        |        |        |        |
|      | 85%    | w      |        |        |        |        |        |
|      |        | alking |        |        |        |        |        |
|      | 4 yr   | s      |        |        |        |        |        |
|      | 100%   | upport |        |        |        |        |        |
+------+--------+--------+--------+--------+--------+--------+--------+
| *    | 7      | 16     | 2(1yr) | 0      | 0      | 3      | 0      |
| *Rev |        | (7?)   |        |        |        |        |        |
| isio |        |        |        |        |        |        |        |
| ns** |        | su     |        |        |        |        |        |
|      |        | rvivor |        |        |        |        |        |
|      |        | ship   |        |        |        |        |        |
|      |        | 94% @  |        |        |        |        |        |
|      |        | 6 yrs  |        |        |        |        |        |
|      |        |        |        |        |        |        |        |
|      |        | 88%    |        |        |        |        |        |
|      |        | cumu   |        |        |        |        |        |
|      |        | lative |        |        |        |        |        |
|      |        | @ 6yrs |        |        |        |        |        |
+------+--------+--------+--------+--------+--------+--------+--------+
| **R  | -Poly  | -Poly  | -deep  |        | -Wound | -deep  |        |
| easo | (mul   | dis    | in     |        | h      | inf    |        |
| ns** | tiple) | locati | fectio |        | ealing | ection |        |
|      | dis    | on(4%) | n(1yr) |        | probs  |        |        |
|      | locati |        |        |        |        | -pain  |        |
|      | on(11) | -Deep  | -poly  |        | medial |        |        |
|      |        | inf    | s      |        | epic   | -PCL   |        |
|      | -      | ection | ubluxa |        | ondyle | i      |        |
|      | Insert |        | tion(3 |        | av     | nsuffi |        |
|      | sublu  | -Lat   | mo)    |        | ulsion | ciency |        |
|      | xation | com    |        |        |        |        |        |
|      | (1)    | partmt | -Fr    |        | IPL    |        |        |
|      |        |        | acture |        | disr   |        |        |
|      | -Pt    | degene |        |        | uption |        |        |
|      | d      | ration | -Fi    |        |        |        |        |
|      | islike |        | broart |        |        |        |        |
|      |        | -A     | hrosis |        |        |        |        |
|      |        | septic |        |        |        |        |        |
|      |        | loo    | -RSD   |        |        |        |        |
|      |        | sening |        |        |        |        |        |
|      |        | :femur |        |        |        |        |        |
|      |        | and    |        |        |        |        |        |
|      |        | tibia  |        |        |        |        |        |
|      |        |        |        |        |        |        |        |
|      |        | -poly  |        |        |        |        |        |
|      |        | wear   |        |        |        |        |        |
|      |        |        |        |        |        |        |        |
|      |        | -pa    |        |        |        |        |        |
|      |        | tellar |        |        |        |        |        |
|      |        | compli |        |        |        |        |        |
|      |        | cation |        |        |        |        |        |
|      |        |        |        |        |        |        |        |
|      |        | -RA    |        |        |        |        |        |
|      |        | onset  |        |        |        |        |        |
|      |        |        |        |        |        |        |        |
|      |        | -Auto  |        |        |        |        |        |
|      |        | Ac     |        |        |        |        |        |
|      |        | cident |        |        |        |        |        |
|      |        |        |        |        |        |        |        |
|      |        | -P     |        |        |        |        |        |
|      |        | atella |        |        |        |        |        |
|      |        | Di     |        |        |        |        |        |
|      |        | slocat |        |        |        |        |        |
|      |        |        |        |        |        |        |        |
|      |        | -im    |        |        |        |        |        |
|      |        | proper |        |        |        |        |        |
|      |        | ali    |        |        |        |        |        |
|      |        | gnment |        |        |        |        |        |
|      |        |        |        |        |        |        |        |
|      |        | -me    |        |        |        |        |        |
|      |        | niscal |        |        |        |        |        |
|      |        | cyst   |        |        |        |        |        |
|      |        |        |        |        |        |        |        |
|      |        | 1 pt   |        |        |        |        |        |
|      |        | death  |        |        |        |        |        |
+------+--------+--------+--------+--------+--------+--------+--------+
| *    | 5.4%   | 15.4   | 1.7    |        |        | 1.7    |        |
| *Rev |        |        |        |        |        |        |        |
| Rate |        |        |        |        |        |        |        |
| (sp  |        |        |        |        |        |        |        |
| onso |        |        |        |        |        |        |        |
| r)** |        |        |        |        |        |        |        |
+------+--------+--------+--------+--------+--------+--------+--------+

\*Note that in all of the studies 85-100% of patients had OA as a
primary diagnosis.

**[International Studies]{.underline}**

+------------------+----------+------+---------+----+-----+--------+
|                  | **Zimmer |      |         | ** |     |        |
|                  | MOBILE   |      |         | Ne |     |        |
|                  | BEARING  |      |         | xG |     |        |
|                  | KNEES**  |      |         | en |     |        |
|                  |          |      |         | LP |     |        |
|                  |          |      |         | S- |     |        |
|                  |          |      |         | Fl |     |        |
|                  |          |      |         | ex |     |        |
|                  |          |      |         | ** |     |        |
+------------------+----------+------+---------+----+-----+--------+
| \# enrolled      | 1,254    |      |         | 3  |     |        |
|                  |          |      |         | 90 |     |        |
+------------------+----------+------+---------+----+-----+--------+
| **Insall         | A        | B    | C       | A  | B   | C      |
| Categories**     |          |      |         |    |     |        |
+------------------+----------+------+---------+----+-----+--------+
| **1 yr**         | 447/552  | 223  | 143/213 | 8  | 24  | 55/60  |
|                  | (80%)    | /256 | (81%)   | 0/ | /30 |        |
|                  |          |      |         | 86 |     |        |
+------------------+----------+------+---------+----+-----+--------+
| **2 yr (%)**     | 223/256  | 117  | 74/100  | 1  | 3/5 | 4/4    |
|                  | (87%)    | /140 | (74%)   | 5/ | (6  |        |
|                  |          | .(83 |         | 15 | 0%) |        |
|                  |          | .6%) |         |    |     |        |
+------------------+----------+------+---------+----+-----+--------+
| **Mean F/U**     | 33% at 2 |      |         |    |     |        |
|                  | yrs      |      |         |    |     |        |
+------------------+----------+------+---------+----+-----+--------+
| **KSS/HSS**      | 81%      | 87%  | 67%     | 9  | 79  | 91     |
|                  |          |      |         | 3% |     |        |
| **               | 85.7     | 8    | 74%     |    | 67  | 100    |
| Good-Excellent** |          | 3.8% |         | 1  |     |        |
|                  |          |      |         | 00 |     |        |
+------------------+----------+------+---------+----+-----+--------+
| **Revisions**    | 8 total  |      |         | 2  |     |        |
|                  | 0.6%     |      |         | t  |     |        |
|                  |          |      |         | ot |     |        |
|                  |          |      |         | al |     |        |
+------------------+----------+------+---------+----+-----+--------+
| **Reasons**      | -        |      |         | De |     |        |
|                  | Patellar |      |         | ep |     |        |
|                  | compl    |      |         | i  |     |        |
|                  | ications |      |         | nf |     |        |
|                  |          |      |         | ec |     |        |
|                  | -Fixed   |      |         | ti |     |        |
|                  | flexion  |      |         | on |     |        |
|                  | def      |      |         | (3 |     |        |
|                  | ormity/s |      |         | m  |     |        |
|                  | tiffness |      |         | o) |     |        |
|                  |          |      |         |    |     |        |
|                  | -uns     |      |         | I  |     |        |
|                  | pecified |      |         | ns |     |        |
|                  |          |      |         | ta |     |        |
|                  | Comp     |      |         | bi |     |        |
|                  | lication |      |         | li |     |        |
|                  | rate     |      |         | ty |     |        |
|                  | 3.6%     |      |         | (6 |     |        |
|                  |          |      |         | m  |     |        |
|                  |          |      |         | o) |     |        |
+------------------+----------+------+---------+----+-----+--------+

Data from two international clinical outcomes studies provide robust
evidence of the clinical success of mobile bearing knees in general
usage. These data sets represent a variety of surgical skills among
numerous surgeons, in numerous countries, from general patients not
limited by inclusion/exclusion criteria. Currently, 2 year data is

available from a total of 243 patients. The published data is summarized
in Volume 2, Appendix 3.

[Overall Summary]{.underline}

The sponsor provides summaries of studies grouped by mobile bearing
knees types. Even within these groupings, the results are variable and
very few prospective randomized controlled studies are reviewed,
particularly those comparing mobile bearing knees to fixed bearing total
knee arthroplasty out comes. Patient population varies as do indications
( Unicondylar vs. bicondylar) Although retrospective studies are useful
as they provide longer term information, the data collected
retrospectively has inherent flaws due in large part to missing
information and the need for interpretation. Thus this data should be
reviewed with some caution. It is difficult to group all the different
types of mobile bearing knees into one group as they appear to have very
variable results, even within the same group. The FDA believes the
mechanics and adverse events may be unique for tricompartmental
(patellofemorotibial) mobile bearing knees as compared to
bicompartmental (femorotibial)and therefore recommend that a separate
category be proposed rather than grouping these two types of devices
together.

[Multidirectional platform devices]{.underline}

This consists of 2 prospective (none randomized) and 2 retrospective
studies which discuss 4 different devices implanted in 425 patients/491
knees (includes bilateral) with a major diagnosis of osteoarthritis
(\>70%). Follow-up averaged 4.1 years in the range of 2-8 years with
variable patient follow-up percentages( as low as 35%) . The outcomes
results are variable and range from poorer results for the Accord device
(Duffy) at 5 years with 16% severe pain, mean knee score 60/100 and
function score 42/100 and 58% survivorship at 10 yrs., to better results
for the Rotaglide (Polyzoides) with pain in less than 3% of the
patients(knee scores not reported). Knee scores in the other 2 studies
range from 155-188/200. Some of the patients in these reviews were
excluded if they had a revision.

+-------------+-------------+-------------+-------------+-------------+
| **Multi     |             |             |             |             |
| directional |             |             |             |             |
| Platform    |             |             |             |             |
| Devices     |             |             |             |             |
| Meta        |             |             |             |             |
| analysis**  |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| **          | **Duffy &   | **Kaper et. | **M         | *           |
| reference** | Philipson** | Al.**       | organ-Jones | *Polyzoides |
|             |             |             | et. al.**   | et. al.**   |
|             |             |             | prospective |             |
|             |             |             |             | re          |
|             |             |             |             | trospective |
+-------------+-------------+-------------+-------------+-------------+
| **Device    | Accord TKA  | Self        |             | Rotaglide   |
| Name**      |             | Aligning I  |             | TKA         |
+-------------+-------------+-------------+-------------+-------------+
| **Knees     | 74/61       | 172/141 OA  | 75/62       | 170         |
| /patients** |             |             |             | cemented    |
|             | 35% f/u     |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| **Age mean  | 68-69       | 71 (47-90)  | 67          | 66          |
| (range)**   |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| **Deaths**  | 16 pts (20  | 41          |             |             |
|             | knees)      |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| **Lost to   | 6           | 1 @ 5 yrs   |             |             |
| f/u**       |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| **Revis     | 25          | 15 (8.1%)   | 0           | 0           |
| ions/surg** |             |             |             |             |
|             | (19         |             |             |             |
|             | i           |             |             |             |
|             | nstability) |             |             |             |
|             | 34%         |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| **Comp      | 1           | 4           | No          | No platform |
| lications** |             |             | d           | dislocation |
|             | 8           | 4           | islocation, |             |
| **          |             |             | s           | No          |
| Infection** | 2           | 2           | ubluxation, | mechanical  |
|             |             |             | breakage,   | implant     |
| **Aseptic   | 3           | 4           | subsidence  | failures    |
| loosening** |             |             | or          |             |
|             | 8           | 1           | osteolysis  | 1ptw        |
| **Poly      |             |             |             | /fracture@6 |
| wear**      | 19          | 1           | 1 patella   | wks         |
|             |             |             | replacement |             |
| **          |             |             |             |             |
| Fractures** |             |             |             |             |
|             |             |             |             |             |
| **          |             |             |             |             |
| Stiffness** |             |             |             |             |
|             |             |             |             |             |
| **Pain**    |             |             |             |             |
|             |             |             |             |             |
| **Dis       |             |             |             |             |
| locations** |             |             |             |             |
|             |             |             |             |             |
| **Lysis**   |             |             |             |             |
|             |             |             |             |             |
| **In        |             |             |             |             |
| stability** |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| **NSS       | 60          | KSS pre 81  | KSS pre 96  | 95%         |
| (mean)**    |             |             |             | BritishOA   |
|             | 35% good    | Post -155   | Post 188    | score       |
|             | -           |             |             | goo         |
|             | -excellent, |             |             | d/excellent |
|             | fxn 4% good |             |             |             |
|             | to          |             |             |             |
|             | excellent   |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| **Function  | 42          | ROM 0^o^    | ROM 2yr     |             |
| score**     |             |             | 133^o^      |             |
|             |             | Post 111^o^ |             |             |
+-------------+-------------+-------------+-------------+-------------+
| **Sur       | 10yr= 58%   | 91.7 %      | []{.mark}   | []{.mark}   |
| vivorship** |             | (poly wear  |             |             |
|             |             | =98.8%      |             |             |
+-------------+-------------+-------------+-------------+-------------+
| **F/U       | 5 yrs, 4 mo | 5.6 yrs     | 2.5 yrs     | 2-5 yrs     |
| (mean)**    |             | (5-8yrs)    |             |             |
+-------------+-------------+-------------+-------------+-------------+
| **Comment** | Poor as     | Pt          |             |             |
|             | compared to | s           |             |             |
|             | c           | atisfaction |             |             |
|             | onventional | = 94%       |             |             |
|             | TKA 16%     |             |             |             |
|             | severe pain |             |             |             |
+-------------+-------------+-------------+-------------+-------------+

[Rotating platform Devices]{.underline}

[This consists of 2 prospective (one randomized) and 2 retrospective
studies which discuss 1 device (LCS) implanted in 744 patients/939 knees
(includes bilateral) with a major diagnosis of osteoarthritis (\>70%).
Follow-up averaged 1-12 years with variable patient follow-up
percentages( as low as 55%) . The outcomes results are variable. Knee
scores were not reported in one study, but range from KSS clinical of
90-91/100 (165/200) to 159/200 . 10% of knees had pain in one study.
Survivorship ranged from 88-94% in 2 retrospective studies at 14 and 11
years. Revision rate from 3 studies range from 0-7%.]{.underline}

+---------------+-------------+-----------+------------+------------+
| **Rotating    |             |           |            |            |
| Platform      |             |           |            |            |
| Devices**     |             |           |            |            |
+---------------+-------------+-----------+------------+------------+
| **Reference** | Callaghan   | Grodzki   | Sorrells   | Sorrells   |
|               | et.al.      | et. al.   |            | retro      |
+---------------+-------------+-----------+------------+------------+
| **Device      | LCS         | PFC/LCS   | LCS        | LCS        |
| Name**        |             |           |            |            |
+---------------+-------------+-----------+------------+------------+
| **Kne         | 119/86      |           | 665/521    | 1117/9     |
| es/patients** |             |           |            |            |
+---------------+-------------+-----------+------------+------------+
| **Age mean    | 70          | 73        | 70         | 56         |
| (range)**     |             |           |            |            |
+---------------+-------------+-----------+------------+------------+
| **Deaths**    | 18          |           | []{.mark}  | 15/18      |
|               |             |           |            | knees      |
+---------------+-------------+-----------+------------+------------+
| **Lost to     | 5 knees     |           |            | 26 knee/25 |
| f/u**         |             |           |            | pt         |
+---------------+-------------+-----------+------------+------------+
| **Rev         | 0           |           | 13 (2%)    | 8 (6.8%)   |
| isions/surg** |             |           |            |            |
+---------------+-------------+-----------+------------+------------+
| **[Co         | 0           | No        | 4          | 1          |
| mplications]{ |             | in        |            |            |
| .underline}** | 0           | formation | 1          | 1          |
|               |             | because   |            |            |
| **Infection** | 0           | article   | 2          | 2          |
|               |             | was in    |            |            |
| **Aseptic**   |             | German    | 7          | 2          |
|               |             |           |            |            |
| **loosening** |             |           | 6          | 4          |
|               |             |           |            |            |
| *             |             |           | 1          |            |
| *Osteolysis** |             |           |            |            |
|               |             |           | 1/1        |            |
| **Poly wear** |             |           |            |            |
|               |             |           |            |            |
| **Fractures** |             |           |            |            |
|               |             |           |            |            |
| **Stiffness** |             |           |            |            |
|               |             |           |            |            |
| **Pain**      |             |           |            |            |
|               |             |           |            |            |
| **            |             |           |            |            |
| Dislocation** |             |           |            |            |
|               |             |           |            |            |
| **Mal         |             |           |            |            |
| positioning** |             |           |            |            |
|               |             |           |            |            |
| **Laxity**    |             |           |            |            |
|               |             |           |            |            |
| **Sub         |             |           |            |            |
| lux/subside** |             |           |            |            |
+---------------+-------------+-----------+------------+------------+
| **NSS         |             | PFC =130  | 98% good   | 85%        |
| (mean)**      |             |           | to         | good       |
|               |             | LCS =160  | excellent  | -excellent |
|               |             |           | at 11 yrs  |            |
+---------------+-------------+-----------+------------+------------+
| **Function    | ROM ave:    |           |            |            |
| score**       |             |           |            |            |
|               | 0-102^o^    |           |            |            |
+---------------+-------------+-----------+------------+------------+
| **S           | 100%        | \*        | 94.7%      | 88.1%@14yr |
| urvivorship** |             |           |            |            |
+---------------+-------------+-----------+------------+------------+
| **F/U         |             | 1 yr      | 1-11 yrs   | 8.5 yrs    |
| (mean)**      |             |           |            |            |
+---------------+-------------+-----------+------------+------------+
| **Comment**   | Avoidance   |           |            |            |
|               | of a        |           |            |            |
|               | flexion gap |           |            |            |
|               | thought to  |           |            |            |
|               | account for |           |            |            |
|               | no          |           |            |            |
|               | d           |           |            |            |
|               | islocation/ |           |            |            |
|               |             |           |            |            |
|               | osteolysis  |           |            |            |
|               | from        |           |            |            |
|               | backside    |           |            |            |
|               | wear        |           |            |            |
+---------------+-------------+-----------+------------+------------+

\* blank spaces indicate that information was not available in reference

[Meniscal Bearing Devices]{.underline}

This consists of 5 prospective (one randomized) and 3 retrospective
studies which discuss 2 devices (LCS) implanted in 1666 knees (includes
bilateral) with a major diagnosis of osteoarthritis (\>70%). Follow-up
averaged 1-11.5 years with variable patient follow-up percentages( as
low as 60%). The outcomes results are variable. Knee scores were not
reported in one study, but range from KSS clinical of 70-94/100.
Survivorship 93-99% in 5 retrospective studies.. Revision rate from 5
studies range from 1-9%. In the one randomized study the mobile bearing
knees and fixed knees were similar.

+--------+-------+------+----+-----+------+-----+-------+----------+
| **Me   |       |      |    |     |      |     |       |          |
| niscal |       |      |    |     |      |     |       |          |
| B      |       |      |    |     |      |     |       |          |
| earing |       |      |    |     |      |     |       |          |
| Dev    |       |      |    |     |      |     |       |          |
| ices** |       |      |    |     |      |     |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
| *      | Bert  | Hart | Jo | Jor | Kim  | Mi  | M     | Ro       |
| *Refer |       | ford | rd | dan |      | nns | uller | senbergH |
| ence** |       |      | an |     |      |     |       | enderson |
+--------+-------+------+----+-----+------+-----+-------+----------+
| **     | LCS   |      | L  | LCS | LCS  | Mi  | LCS   | LCS/PCR  |
| Device |       |      | CS | Un  | /AMK | nns | un    |          |
| Name** |       |      | p  | cem |      | Me  | resur |          |
|        |       |      | ro | ent |      | nis | faced |          |
|        |       |      | sp |     |      | cal | pa    |          |
|        |       |      |    |     |      |     | tella |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
| **Knee | 43/   | 139  | 1  | 4   | 120  | 165 | 436   | 35/27    |
| s/pati |       | /104 | 60 | 73/ | b    |     |       |          |
| ents** |       |      | /1 | 375 | ilat | RA  |       |          |
|        |       | 80   | 41 |     |      | and |       |          |
|        |       | ce   |    |     |      | OA  |       |          |
|        |       | ment |    |     |      | (5  |       |          |
|        |       |      |    |     |      | 7%) |       |          |
|        |       | 50un |    |     |      |     |       |          |
|        |       | ceme |    |     |      |     |       |          |
|        |       |      |    |     |      |     |       |          |
|        |       | 9    |    |     |      |     |       |          |
|        |       | hy   |    |     |      |     |       |          |
|        |       | brid |    |     |      |     |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
| **Age  | 63    | 66   | 68 | 68  | 65   | 67  |       | 72       |
| mean   |       |      | yr |     |      |     |       |          |
| (ra    |       |      | OA |     |      |     |       |          |
| nge)** |       |      | p  |     |      |     |       |          |
|        |       |      | ts |     |      |     |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
| **De   | 0     | 37   | 6  | 39  | 0    |     |       | 3        |
| aths** |       | k    | 6k | (34 |      |     |       |          |
|        |       | nees | ne | af  |      |     |       |          |
|        |       |      | es | ter |      |     |       |          |
|        |       |      |    | 24  |      |     |       |          |
|        |       |      |    | mo) |      |     |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
| **Lost |       | 47   |    | 63  | 4    |     |       | 4        |
| to     |       | k    |    |     |      |     |       |          |
| f/u**  |       | nees |    |     |      |     |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
| **Revi | 4     | 10   | 2  | 18  | 2    | 8   |       | 1 (2.9%) |
| sions/ | (     |      | (0 | (3. | /2(1 |     |       |          |
| surg** | 9.3%) |      | .8 | 8%) | .7%) |     |       |          |
|        |       |      | %) |     |      |     |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
| *      |       |      |    |     |      |     |       |          |
| *[Comp |       |      |    |     |      |     |       |          |
| licati |       |      |    |     |      |     |       |          |
| ons]{. |       |      |    |     |      |     |       |          |
| underl |       |      |    |     |      |     |       |          |
| ine}** |       |      |    |     |      |     |       |          |
|        |       |      |    |     |      |     |       |          |
| *      |       |      |    |     |      |     |       |          |
| *Infec |       |      |    |     |      |     |       |          |
| tion** |       |      |    |     |      |     |       |          |
|        |       |      |    |     |      |     |       |          |
| **Ase  |       |      |    |     |      |     |       |          |
| ptic** |       |      |    |     |      |     |       |          |
|        |       |      |    |     |      |     |       |          |
| *      |       |      |    |     |      |     |       |          |
| *loose |       |      |    |     |      |     |       |          |
| ning** |       |      |    |     |      |     |       |          |
|        |       |      |    |     |      |     |       |          |
| *      |       |      |    |     |      |     |       |          |
| *Fract |       |      |    |     |      |     |       |          |
| ures** |       |      |    |     |      |     |       |          |
|        |       |      |    |     |      |     |       |          |
| **D    |       |      |    |     |      |     |       |          |
| isloca |       |      |    |     |      |     |       |          |
| tion** |       |      |    |     |      |     |       |          |
|        |       |      |    |     |      |     |       |          |
| **Subl |       |      |    |     |      |     |       |          |
| ux/sub |       |      |    |     |      |     |       |          |
| side** |       |      |    |     |      |     |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
|        |       | 3    |    | 5   |      |     |       | 1        |
+--------+-------+------+----+-----+------+-----+-------+----------+
|        |       | 7(hi |    | 2   |      |     |       |          |
|        |       | in   |    |     |      |     |       |          |
|        |       | unce |    |     |      |     |       |          |
|        |       | ment |    |     |      |     |       |          |
|        |       |      |    |     |      |     |       |          |
|        |       | 27%  |    |     |      |     |       |          |
|        |       | /31% |    |     |      |     |       |          |
|        |       | l    |    |     |      |     |       |          |
|        |       | oose |    |     |      |     |       |          |
|        |       | ning |    |     |      |     |       |          |
|        |       | fem  |    |     |      |     |       |          |
|        |       | ur/t |    |     |      |     |       |          |
|        |       | ibia |    |     |      |     |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
|        |       |      |    |     | 1    |     |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
|        | 4:3   | 1    |    | 5   | 1    | 8   |       |          |
|        | -2wk, |      |    |     |      |     |       |          |
|        | 1-6mo |      |    |     |      |     |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
|        |       |      |    | 4/2 |      |     |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
| *      |       |      |    | 7   |      |     |       |          |
| *Fract |       |      |    |     |      |     |       |          |
| ures** |       |      |    |     |      |     |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
| **NSS  | 91%   |      |    | 92  | 9    | 75% | NJOHS | 83       |
| (m     | good  |      |    | /93 | 4.4/ | exc | =90 @ | (14PTS)  |
| ean)** | -exce |      |    |     | 93.3 | ell | 5yr   |          |
|        | llent |      |    |     |      | ent |       | 60       |
|        |       |      |    |     |      | 9%f |       | (5=Fair) |
|        |       |      |    |     |      | air |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
| **Fu   |       |      |    |     | ROM  | F   |       |          |
| nction |       |      |    |     | =123 | lex |       |          |
| s      |       |      |    |     | /121 | ion |       |          |
| core** |       |      |    |     |      | 8   |       |          |
|        |       |      |    |     |      | 9-1 |       |          |
|        |       |      |    |     |      | 03o |       |          |
|        |       |      |    |     |      |     |       |          |
|        |       |      |    |     |      | Dec |       |          |
|        |       |      |    |     |      | in  |       |          |
|        |       |      |    |     |      | sta |       |          |
|        |       |      |    |     |      | bil |       |          |
|        |       |      |    |     |      | ity |       |          |
|        |       |      |    |     |      |     |       |          |
|        |       |      |    |     |      | Dec |       |          |
|        |       |      |    |     |      | f   |       |          |
|        |       |      |    |     |      | lex |       |          |
|        |       |      |    |     |      | ion |       |          |
|        |       |      |    |     |      | def |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
| **Su   |       | 93%  | 9  | 94  | 98%  |     |       | 97%      |
| rvivor |       |      | 9. | .6% |      |     |       |          |
| ship** |       |      | 5% | (8y |      |     |       |          |
|        |       |      |    | rs) |      |     |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
| **F/U  | 1 yr  | 7.8  | 12 | 2   | 7.4  | 0-  |       | ?        |
| (m     |       | yr   | yr | -10 |      | 5yr |       |          |
| ean)** |       |      |    | (4  |      |     |       |          |
|        |       |      |    | .7) |      |     |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+
| **Com  | P     |      |    |     |      |     |       |          |
| ment** | roper |      |    |     |      |     |       |          |
|        | m     |      |    |     |      |     |       |          |
|        | easur |      |    |     |      |     |       |          |
|        | ement |      |    |     |      |     |       |          |
|        | of    |      |    |     |      |     |       |          |
|        | fl    |      |    |     |      |     |       |          |
|        | exion |      |    |     |      |     |       |          |
|        | gap   |      |    |     |      |     |       |          |
|        | cri   |      |    |     |      |     |       |          |
|        | tical |      |    |     |      |     |       |          |
|        | to    |      |    |     |      |     |       |          |
|        | pr    |      |    |     |      |     |       |          |
|        | event |      |    |     |      |     |       |          |
|        | d     |      |    |     |      |     |       |          |
|        | isloc |      |    |     |      |     |       |          |
|        | ation |      |    |     |      |     |       |          |
|        | of    |      |    |     |      |     |       |          |
|        | ele   |      |    |     |      |     |       |          |
|        | ments |      |    |     |      |     |       |          |
+--------+-------+------+----+-----+------+-----+-------+----------+

[Combination of Rotating Platform and meniscal Bearing in same
study]{.underline}

This consists of 3 prospective (none randomized) and 7 retrospective
studies which discuss 6 devices implanted in 8433 knees (includes
bilateral) with a major diagnosis of osteoarthritis (\>70%). Follow-up
averaged 20 months-13.5 years with variable patient follow-up
percentages. The outcomes results are variable. Survivorship is 90-100%
in at 5-10 yrs. Revision rates range to 8%.

<table>
<colgroup>
<col style="width: 8%" />
<col style="width: 6%" />
<col style="width: 7%" />
<col style="width: 6%" />
<col style="width: 6%" />
<col style="width: 7%" />
<col style="width: 8%" />
<col style="width: 7%" />
<col style="width: 5%" />
<col style="width: 20%" />
<col style="width: 7%" />
<col style="width: 7%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="10"><strong>Combination of Rotating Platform and meniscal
Bearing in same study details on table Vol. 2, Appendix
3,p.240</strong></td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td><strong>Reference</strong></td>
<td>Buechel</td>
<td><p>Buechel</p>
<p>/Pappas</p></td>
<td>Callaghan (8 reports)</td>
<td>Keblish</td>
<td>Keblish</td>
<td>Munzinger</td>
<td>Papchristou</td>
<td><p>Sanchez</p>
<p>Sotelo</p></td>
<td>Steil et al</td>
<td>Weissinger</td>
<td>Thompson</td>
</tr>
<tr class="odd">
<td><p><strong>Device</strong></p>
<p><strong>Name</strong></p></td>
<td>NJLCS</td>
<td>NJLCS</td>
<td><p>LCS/</p>
<p>Oxford</p></td>
<td>LCS</td>
<td><p>LCS</p>
<p>Moveable-bearing w/ anatomic femoral groove</p></td>
<td>LCS</td>
<td><p>Oxford 9 pts</p>
<p>Endo-model</p>
<p>18 pts</p></td>
<td>LCS</td>
<td><p>LCS</p>
<p>147</p>
<p>Meniscal</p>
<p>44 Rot Plat</p></td>
<td>LCS</td>
<td>LCS</td>
</tr>
<tr class="even">
<td><p><strong>Knees</strong></p>
<p><strong>/patients</strong></p></td>
<td>373/282</td>
<td><p>357: 149 cemented</p>
<p>208 uncement</p>
<p>MB=140</p>
<p>RP= 217</p></td>
<td></td>
<td><p>963/918 (MC)</p>
<p>275 personal series</p></td>
<td><p>104/52</p>
<p>bilateral</p>
<p>1 side patella resurface</p>
<p>88 uncementd</p>
<p>16 cement</p></td>
<td>235</td>
<td></td>
<td>101 pts</td>
<td>290/250</td>
<td>42/41</td>
<td>33/31</td>
</tr>
<tr class="odd">
<td><strong>Age mean (range)</strong></td>
<td>68</td>
<td>62</td>
<td>35-90</td>
<td>68</td>
<td>69</td>
<td>68</td>
<td>63-72</td>
<td>66</td>
<td>69</td>
<td>65.8</td>
<td>73</td>
</tr>
<tr class="even">
<td><strong>Deaths</strong></td>
<td></td>
<td>1</td>
<td>42</td>
<td></td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>0</td>
<td>35</td>
<td>1</td>
<td></td>
</tr>
<tr class="odd">
<td><strong>Lost to f/u</strong></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>131 less than 2yr</td>
<td></td>
<td></td>
<td>99</td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td><p><strong>Revisions</strong></p>
<p><strong>/surg</strong></p></td>
<td>1</td>
<td>15 (4%)</td>
<td>65</td>
<td>9 (personal 3.3%)</td>
<td>1</td>
<td>8 (3%)</td>
<td><p>3 total</p>
<p>2 Oxford</p>
<p>(22%)</p>
<p>1 endo</p></td>
<td>8 /(8%)</td>
<td>5 (5.4%)</td>
<td>0</td>
<td></td>
</tr>
<tr class="odd">
<td><strong>Infection</strong></td>
<td>3</td>
<td>7</td>
<td></td>
<td></td>
<td></td>
<td>1</td>
<td>1</td>
<td>1</td>
<td></td>
<td></td>
<td>1</td>
</tr>
<tr class="even">
<td><strong>Aseptic loosening</strong></td>
<td>3</td>
<td>6</td>
<td></td>
<td>4</td>
<td></td>
<td></td>
<td>2</td>
<td>1</td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td><strong>Osteolysis</strong></td>
<td>3(1.8%)</td>
<td>0</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>2</td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td><strong>Poly wear</strong></td>
<td></td>
<td></td>
<td></td>
<td>3</td>
<td></td>
<td></td>
<td></td>
<td>1</td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td><strong>Fractures</strong></td>
<td>1</td>
<td>2</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td><strong>Stiffness</strong></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td><strong>Pain</strong></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td><p><strong>Dis</strong></p>
<p><strong>location</strong></p></td>
<td>5</td>
<td><p>MB=.7%</p>
<p>RP= 3.2%</p></td>
<td>Most common</td>
<td></td>
<td></td>
<td>1Patellar probs responsible for comps</td>
<td></td>
<td>2</td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td><p><strong>Sublux/</strong></p>
<p><strong>subside</strong></p></td>
<td></td>
<td></td>
<td></td>
<td>4</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td><strong>Fractures</strong></td>
<td>1</td>
<td><p>2+</p>
<p>1 trauma</p></td>
<td></td>
<td>2 patellar</td>
<td></td>
<td></td>
<td></td>
<td>femur</td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="odd">
<td><p><strong>NSS</strong></p>
<p><strong>(mean)</strong></p></td>
<td><p>PCR 68% excellent</p>
<p>CRP 47%</p></td>
<td><p>cement</p>
<p>85% excellent</p>
<p>11.5% poor</p>
<p>uncement</p>
<p>92% excellent</p>
<p>6% poor</p></td>
<td></td>
<td><p>Cemented</p>
<p>LCS-96% excellent</p>
<p>Uncement</p>
<p>LCS-97%</p>
<p>excellent</p></td>
<td>89.9 mean</td>
<td>95% excellent/good 4.2 yr</td>
<td></td>
<td>93</td>
<td></td>
<td></td>
<td><p>Dec pain</p>
<p>All to 21</p>
<p>pain free</p>
<p>12</p>
<p>occasional</p></td>
</tr>
<tr class="even">
<td><strong>Function score</strong></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td>78 ave</td>
<td></td>
<td></td>
<td>Dec ROM</td>
</tr>
<tr class="odd">
<td><p><strong>Survivor</strong></p>
<p><strong>ship</strong></p></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td><p>97.5%MB 7 yrs</p>
<p>100% RP</p></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td><p><strong>F/U</strong></p>
<p><strong>(mean)</strong></p></td>
<td>20 yr</td>
<td>91mo/52mo</td>
<td>5-11 yrs</td>
<td>2-8yr</td>
<td>5.24 yr</td>
<td></td>
<td></td>
<td>5.2yr</td>
<td></td>
<td>21 mo</td>
<td>20 mo</td>
</tr>
<tr class="odd">
<td><strong>Comment</strong></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td><p>Nonresurf</p>
<p>patella same as resurfaced patella</p></td>
<td>Acceptable results re: -degree of stability - pain relief</td>
<td></td>
<td></td>
<td>IM alignmt flexi/extgap balancing impt</td>
<td></td>
<td></td>
</tr>
</tbody>
</table>

[Unicondylar Meniscal Bearing]{.underline}

This consists of 12 prospective (one randomized) and 8 retrospective
studies which investigates 3 devices (LCS, Oxford, Lotus) implanted in
2385 knees (includes bilateral) with a major diagnosis of osteoarthritis
(\>90% in all except one study). Several studies had small sample sizes
(\<60 pts) Follow-up averaged 2-11 years with variable patient follow-up
percentages.(some less than 50%) The outcomes results are variable,
47-98% success. In one study, RA patients had better outcomes than the
OA patients Survivorship 66 (6 yrs)-100% in at 5-10 yrs. Revision rates
are high in several studies, reported range 0 to 30%. In this grouping,
successful results were associated with specific patient inclusion and
exclusion criteria, and patient anatomy.

<table>
<colgroup>
<col style="width: 9%" />
<col style="width: 10%" />
<col style="width: 10%" />
<col style="width: 10%" />
<col style="width: 10%" />
<col style="width: 9%" />
<col style="width: 10%" />
<col style="width: 10%" />
<col style="width: 10%" />
<col style="width: 10%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="10"><strong>Unicondylar Meniscal Bearing</strong></td>
</tr>
<tr class="even">
<td><strong>REF</strong></td>
<td><strong>Device</strong></td>
<td><strong>Pts/Knee</strong></td>
<td><strong>Age</strong></td>
<td><strong>Revision</strong></td>
<td><strong>F/U</strong></td>
<td><strong>KSS</strong></td>
<td><strong>Fxn</strong></td>
<td><strong>Survivorship</strong></td>
<td><strong>Complications</strong></td>
</tr>
<tr class="odd">
<td>Argenson</td>
<td>oxford</td>
<td>552</td>
<td></td>
<td>45(8.2%)</td>
<td>14</td>
<td></td>
<td></td>
<td>92%</td>
<td></td>
</tr>
<tr class="even">
<td>Barrett</td>
<td>Oxford bicompart</td>
<td><p>62 pts</p>
<p>RA 46%</p>
<p>OA 54%</p></td>
<td>75</td>
<td>4 (7%)</td>
<td>4.5 yr</td>
<td>83% pain relief</td>
<td><p>ROM:</p>
<p>93-103<sup>o</sup></p>
<p>93-73<sup>o</sup></p></td>
<td></td>
<td><p>4 DVT</p>
<p>2 Dislocation</p>
<p>2 aseptic loosening</p>
<p>5 infxn</p></td>
</tr>
<tr class="odd">
<td>Bourne</td>
<td><p>Oxford Meniscal</p>
<p>Oxford Kinematic I</p></td>
<td><p>67</p>
<p>66</p></td>
<td>67</td>
<td><p>20 (30%)</p>
<p>3</p></td>
<td>5.5 yr</td>
<td><p>82</p>
<p>88</p></td>
<td></td>
<td>9 deaths</td>
<td><p>15 aseptic loosening</p>
<p>2 patellofemoral syn</p>
<p>1 dislocatn</p>
<p>1 infexn</p></td>
</tr>
<tr class="even">
<td>Carr</td>
<td>25 bilateral medial compartment</td>
<td>121/96</td>
<td>69</td>
<td>1(0.8%)</td>
<td>44.4 mo</td>
<td>75% pts no pain</td>
<td>ROM 95-106</td>
<td><p>99.1% @ 9yrs</p>
<p>1 death</p></td>
<td><p>Loosening</p>
<p>displacement</p></td>
</tr>
<tr class="odd">
<td>Cohen</td>
<td>NJOHS</td>
<td>21/20</td>
<td>60</td>
<td>1</td>
<td>10 yrs</td>
<td>16 good-excellent</td>
<td></td>
<td>2 death</td>
<td>Aseptic loosening</td>
</tr>
<tr class="even">
<td>Goodfellow</td>
<td>Oxford Uni Meniscal</td>
<td>103/85</td>
<td>70 OA</td>
<td>9 rev (9.2%)</td>
<td>36 mo</td>
<td>92% No pain</td>
<td></td>
<td>5 deaths</td>
<td><p>4 Aseptic loosening</p>
<p>2 Lysis</p>
<p>3 dislocn</p>
<p>2 infexn</p>
<p>Subluxation</p>
<p>ACL absence greater incidence of failure</p></td>
</tr>
<tr class="odd">
<td>Goodfellow O’Conner</td>
<td>Oxford</td>
<td>125/107</td>
<td>67</td>
<td><p>8 rev</p>
<p>4 failures</p></td>
<td>49 mo</td>
<td>89% pain free</td>
<td><p>Flexion deformity</p>
<p>Flexion worse post op</p></td>
<td>1death</td>
<td><p>1 infxn</p>
<p>5disloc</p>
<p>6Aseptic loosening</p>
<p>2lysis</p></td>
</tr>
<tr class="even">
<td>Goodfellow</td>
<td>Uni</td>
<td>25/22</td>
<td>67 OA, AVN,fx</td>
<td>1</td>
<td>21 mo</td>
<td>92% no –mild pain</td>
<td>Flexion worse post op</td>
<td></td>
<td>1Loosning tibia</td>
</tr>
<tr class="odd">
<td>Gunther</td>
<td>Oxford Uni</td>
<td>53/51</td>
<td>68</td>
<td>11 (21%)</td>
<td>5.2 yr</td>
<td>53% report pain w/activity</td>
<td></td>
<td>Bearing dislocation greater in lateral compartment</td>
<td><p>6 Bearing dislocation</p>
<p>1Plateau fracture</p></td>
</tr>
<tr class="even">
<td>Harding</td>
<td>Oxford I, II</td>
<td>50/50</td>
<td></td>
<td>14 (28%)</td>
<td></td>
<td></td>
<td></td>
<td><p>I 66%</p>
<p>II 86%</p>
<p>100% if indications met?</p></td>
<td>Poor outcome if ACL deficient</td>
</tr>
<tr class="odd">
<td>Keyes</td>
<td>Oxford Unicompartmental</td>
<td></td>
<td></td>
<td>0</td>
<td>5 yr</td>
<td>97.5% good -excellent</td>
<td></td>
<td>100%</td>
<td></td>
</tr>
<tr class="even">
<td>Kumar</td>
<td><p>Oxford</p>
<p>Uni</p></td>
<td>100/</td>
<td>71</td>
<td>7 (7%)</td>
<td>11yr</td>
<td><p>Pre 62</p>
<p>Post 91</p></td>
<td><p>Pre 45</p>
<p>Post 71</p></td>
<td>85%</td>
<td>Aseptic loosening</td>
</tr>
<tr class="odd">
<td><p>McLardy</p>
<p>Smith</p></td>
<td>Oxford Uni</td>
<td>475/</td>
<td><p>&lt;60</p>
<p>&gt;60</p></td>
<td></td>
<td>10yr</td>
<td></td>
<td></td>
<td><p>94%</p>
<p>95%</p></td>
<td></td>
</tr>
<tr class="even">
<td>Murray</td>
<td>Uni congruous mobile poly bearings</td>
<td>143/114</td>
<td>70</td>
<td>5 rev (3.5%)</td>
<td>7.6</td>
<td></td>
<td></td>
<td>98% 10yr</td>
<td>dislocations</td>
</tr>
<tr class="odd">
<td>Price</td>
<td>Oxford Uni</td>
<td><p>40 MIS</p>
<p>20 conv</p>
<p>40ABD TKA</p></td>
<td>57-91</td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td>Rees</td>
<td>Oxford UCA</td>
<td><p>631/507</p>
<p>primary and failed HTO</p></td>
<td>70</td>
<td><p>19 1<sup>o</sup> (3.1%)</p>
<p>5 HTO</p></td>
<td></td>
<td></td>
<td></td>
<td><p>96% 10yr</p>
<p>66%</p></td>
<td>Uni UCA should not be used in failed HTO</td>
</tr>
<tr class="odd">
<td>Sherman</td>
<td>Bilateral Bicompartmental Oxford Meniscal</td>
<td>/32</td>
<td>63</td>
<td>5</td>
<td>51 mo</td>
<td>Pain relief in all but one</td>
<td>No improvements in ROM</td>
<td></td>
<td><p>Infection</p>
<p>Aseptic loosening</p>
<p>Bearing dislocation</p></td>
</tr>
<tr class="even">
<td>Svard</td>
<td>Oxford Meniscal B uni</td>
<td>124/</td>
<td>70</td>
<td>6 (4.8%)</td>
<td>12.5</td>
<td></td>
<td></td>
<td>95% 10yr</td>
<td>Bearing dislocation</td>
</tr>
<tr class="odd">
<td>Vorlat</td>
<td>Oxford Uni</td>
<td>41/39</td>
<td>62</td>
<td>3</td>
<td>5 yrs</td>
<td>87</td>
<td></td>
<td></td>
<td><p>Infection</p>
<p>4 “other”</p></td>
</tr>
<tr class="even">
<td>Weale</td>
<td>Oxford</td>
<td>31/28</td>
<td>70</td>
<td>2</td>
<td></td>
<td></td>
<td>Oxford scale 36.5/48</td>
<td></td>
<td>Aseptic loosening</td>
</tr>
<tr class="odd">
<td>Weale</td>
<td>Oxford Uni</td>
<td>56</td>
<td>80.3</td>
<td>2</td>
<td>1.4</td>
<td>25/28 good or excellent</td>
<td></td>
<td></td>
<td></td>
</tr>
<tr class="even">
<td>Witvoet</td>
<td>Lotus</td>
<td></td>
<td></td>
<td>18 19%</td>
<td>4.6</td>
<td><p>71.9% good</p>
<p>28% poor</p></td>
<td></td>
<td></td>
<td><p>Poly wear</p>
<p>Radiolucencies</p>
<p>Poor techniques/indications</p></td>
</tr>
</tbody>
</table>

The sponsor provides results of review articles which report on large
samples grouped together and summarized with survivorship rates (section
VIII) of over 2500 knees over a 5-17 years evaluation of survivorship,
with a range of survival for those prosthetics of 93% to 100% over this
time. The sponsor states that over 46 knees (Section XI) are available
for review, however it appears that the article chosen include only two
or three designs.

Review of testing shows that the amount of displacement permitted in the
anterior-posterior and medial and lateral directions is highly variable

[Meta analysis]{.underline} (Vol. 1 Section VIII p. 68, Vol2, Appendix
4, p.272) \[see statisticians review, "problems" and analysis below\]

The sponsor presents the result of a meta analysis of 21 studies
reporting the outcome of 22 cohorts which enrolled a total of 2,490
patients (2,870 knees).The mean enrollment per study was 138, greater
than 10 patients per study was allowed however. Mean follow-up was 6
years for these patients, The mean age for these patient was 66 years
with a slight majority of women(62.3%), The majority of patients had
Osteoarthritis (82%) and 13% were bilaterally implanted. The outcome of
the meta analysis was compared to a review of over 9000 patients with
fixed bearing knees reported by Callahan, et al.

This table was provided as a summary. The rate of revision was higher in
the mobile bearing knees at 6.4% vs. 3.8% for fixed bearing knees. Two
particular mobile bearing knees have a high rate of revision (30%): the
oxford phase I and the Accord TKA, which are both, according to the
sponsor no longer used. The mean percentage of patients with good or
excellent outcomes following mobile bearing knees replacement is 90.3%
which was similar to the percentage reported in Callahan's review
(89.3%) and lower than the fixed bearing group when comparing
improvement in a global rating scale outcomes. 91% vs. 100%. "The range
of the percentage of patients with good or excellent outcomes following
mobile bearing knee replacement was 35% to 100%." Vol.2 Appendix 4, p.
277.

+-----------------+-----------------+-----------------+-----------------+
| **Meta analysis |                 |                 |                 |
| results         |                 |                 |                 |
| :Comparison of  |                 |                 |                 |
| mobile bearing  |                 |                 |                 |
| knees vs. fixed |                 |                 |                 |
| bearing knees   |                 |                 |                 |
| (Vol. 1 Section |                 |                 |                 |
| VII, p.68)**    |                 |                 |                 |
+-----------------+-----------------+-----------------+-----------------+
|                 | Mobile bearing  | Mobile bearing  | T               |
|                 | knees outcome   | knees outcome   | ricompartmental |
|                 | result          | result          | Fixed bearing   |
|                 |                 | excluding       | knee outcome    |
|                 |                 | Oxford phase I  | result          |
|                 |                 | and Accord knee |                 |
|                 |                 |                 | (Callahan       |
|                 |                 |                 | et.al.)         |
+-----------------+-----------------+-----------------+-----------------+
| \# knees        | 2870            | 2729            | 9879            |
+-----------------+-----------------+-----------------+-----------------+
| Weighted mean   | 6.0             | 6.4             | 4.1             |
| yrs of f/u      |                 |                 |                 |
+-----------------+-----------------+-----------------+-----------------+
| \# cohorts      | 22              | 20              | 154             |
| analyzed        |                 |                 |                 |
+-----------------+-----------------+-----------------+-----------------+
| Weighted mean%  | 90.3            | 93.4            | 89.3            |
| good/excellent  |                 |                 |                 |
+-----------------+-----------------+-----------------+-----------------+
| \% improvement  | 91.4            | 91.4            | 100             |
| in global       |                 |                 |                 |
| rating scale    |                 |                 |                 |
+-----------------+-----------------+-----------------+-----------------+
| Weighted mean   | 87.8            | 89              | 86.6            |
| postoperative   |                 |                 |                 |
| global rating   |                 |                 |                 |
| scale score     |                 |                 |                 |
+-----------------+-----------------+-----------------+-----------------+
| Weighted mean % | **6.4**         | **5.1\***       | **3.8**         |
| knees with any  |                 |                 |                 |
| revision        |                 |                 |                 |
+-----------------+-----------------+-----------------+-----------------+

\*The revision rate described in these studies is 30%.

The sponsor provided a survival meta-analysis which compared mobile
bearing knees to fixed bearing knees based on survival estimates and
reports reviewed by Callahan. Estimates of implant survival were
extracted from 37 articles (1989-2002) Implants were grouped into
categories: 21 were mobile bearing knees and 16 were fixed bearing. From
these 111 survival estimates were extracted: 40 mobile bearing knees and
71 fixed bearing. The survival rates were "reduced" by the sponsor, when
multiple survival estimates were provided for a unique device, data was
reduced retaining the estimate with the most consistent definition of
"revision" and the longest length of follow-up.

  ----------------- ----------------- ----------------- -----------------
  Mobile bearing                                        
  knees and Fixed                                       
  bearing implant                                       
  survival compared                                     

                    Overall survival  Mobile bearing    Fixed Bearing
                                      knees             Knees

  Mean follow-up    12-17 years       12.5 yrs          17.2 yrs

  WLS estimate      0.9198            0.9263            0.9133
  ----------------- ----------------- ----------------- -----------------

**[Survival meta analysis]{.underline}**

There were 21 articles which summarized survival for devices which were
grouped into a mobile bearing category and 16 grouped into a fixed
bearing category. From these a total of 111 survival estimates were
extracted, with 40 mobile bearing device group estimates, and 71 fixed
bearing device group estimates. For each implant, information on the
average period of follow-up and the total number of knee implants was
tabulated.

There are several problems with the performance of this
meta-analysis**:**

Judgments were made as to which survival reports to include "Since the
number of survival estimates appearing in a given publication ranged
from 1 to 30, data was reduced allowing only one estimate for each
unique device (or set of similar devices within the mobile or fixed
bearing group) from each article. When multiple

survival estimates were provided for a unique device, data was reduced
retaining the estimate with the most consistent definition of revision
and the longest length of follow-up."

Reporting style was also problematic. Authors reported data using the
patient or knee as

the unit of analysis. The number of "cases" or number of knees was used
for this meta analysis. The data abstraction was completed by a research
professional who was educated in the data abstraction requirements. Only
variables that were consistently reported across the majority of studies
could be analyzed. Difficulties in abstracting data resulted from two
types of missing data. The first came when authors did not mention a
variable of interest

in a study. The data abstractor could not determine if the variable was
absent from the study or if it was not reported. The second difficulty
arose when the variable of interest was mentioned as part of a subset of
enrolled patients, but were not mentioned in number or stratified in the
results.

The second problem involved the author's choice of global knee-rating
system and the method of reporting used for the scores. To allow
comparison across studies, the mean preoperative and postoperative
global knee-rating scale score using a 100-point scale was used.

The reporting of complications also showed variability. To allow
comparison across studies, perioperative complication data were not
collected. Complication data that was collected included the following
categories: knees with any complication, knees with any revision, knees
with revision for mechanical failure, knees with revision for aseptic
loosening, and knees with revision for septic loosening. The anatomic
portion of this classification scheme identified the prostheses by
treatment of the posterior cruciate ligament (sparing, sacrificing, or
both sparing/sacrificing of PCL used in same study). When an article
reported across more than one anatomic

classification and provided patient characteristics for each group, the
data were treated as two separate articles. When an article reported
data across more than one classification but did not provide patient
characteristics for each group, the study was considered as a mixed
group of prostheses.

The sponsor does a meta analysis of the new device class based on
studies with greater than 15 patients enrolled per study reporting on
this device, (randomized, non randomized and uncontrolled series, single
investigator, multicenter are all reported in one large group). They
then use these results and compare it to another meta analysis already
completed on another class of devices in which studies were included if
15 patients were enrolled and outcomes were measured by a global out
come scale ( not necessarily all the same scale within and between the
studies) Then the sponsor took the two meta analyses and compared the
mean numbers for follow-up, revision, device survivorship and good to
excellent results, without defining what patient inclusion/exclusion
criteria were, what the criteria for revision are and what scales were
used to rate good to excellent out come in a global scale.

For a meta-analysis, all the demographic and study design, assessment
issues also have to be considered and it does not appear that these are
completed for both analyses The conclusion is that the device classes
have the same outcomes. However, the sponsor only provided 3 actual
randomized studies in which a representative device from each class were
compared prospectively under controlled conditions, and the meta
analysis was not properly performed. Nonetheless the number of patients
implanted is large and the results varied, the summary may be misleading
by providing one mean for all devices. This may be better characterized
by summarizing subgroup results.

**Risk to Health**

Risks may be identified from:

1\. The proposed and final classification rules (based on the
Classification

Panel's recommendation)

2\. Review of the literature

3\. Review of the MDR's

4\. Labeling for the device

**[MDR ( Volume 1, section IX)]{.underline}**

A search of the MDR reports found 385 MDR, 365 were of one manufacturer.

Injuries: 333

Malfunctions: 29

Death : 1

Other: 2

This table was constructed from the sponsor's data listing in summary by
type

+-----------+-------+--------+-------+-------+-------+------+------+
| Type of   | LCS   | LCS    | LCS   | LCS   | LCS   | LCS  | LCS  |
| event     | Post  | Ro     | Men   | Un    | Fe    | Ti   | Pat  |
|           | erior | tating | iscal | known | moral | bial | ella |
|           |       | Pl     | Be    | type  |       |      |      |
|           | Stabi | atform | aring |       |       |      |      |
|           | lized |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Loosening | 3     | 18     |       | 1     | 3     | 4    | 2    |
+-----------+-------+--------+-------+-------+-------+------+------+
| M         |       |        |       |       |       |      | 25   |
| etal/poly |       |        |       |       |       |      |      |
| s         |       |        |       |       |       |      |      |
| eparation |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Bearing   |       | 3      | 35    | 4     |       |      | 2    |
| Fracture  |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Effusion  | 10    | 1      |       | 1     |       |      | 1    |
+-----------+-------+--------+-------+-------+-------+------+------+
| Incorrect |       | 1      |       |       |       |      |      |
| bearing   |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Physician |       |        |       |       | 1     |      |      |
| error     |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Im        | 4     |        |       |       |       |      |      |
| pingement |       |        |       |       |       |      |      |
| and       |       |        |       |       |       |      |      |
| Swelling  |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Infection | 2     |        |       |       | 1     |      | 1    |
+-----------+-------+--------+-------+-------+-------+------+------+
| Unknown   | 2     | 1      | 1     | 1     |       |      | 1    |
+-----------+-------+--------+-------+-------+-------+------+------+
| Pain and  | 46    |        |       | 2     |       |      |      |
| Swelling  |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Broken    | 1     |        |       |       |       |      |      |
| Post      |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Patella   |       |        |       |       |       |      | 2    |
| spin out  |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Poly wear |       | 11     | 11    |       |       |      | 3    |
+-----------+-------+--------+-------+-------+-------+------+------+
| Revision  | 1     |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Painful   | 1     |        |       |       |       |      |      |
| ROM       |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Poly      | 3     |        |       |       |       |      |      |
| defect    |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Su        |       |        | 1     |       |       |      |      |
| bluxation |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Bearing   |       | 2      | 11    |       |       |      | 1    |
| Failure   |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Patella   |       |        |       |       |       |      | 1    |
| locked    |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Impinge   | 1     | 2      |       |       |       |      |      |
| ment/wear |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Fractured |       |        | 2     |       |       |      |      |
| meniscal  |       |        |       |       |       |      |      |
| bearing   |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Loosening |       | 1      |       |       |       |      |      |
| with      |       |        |       |       |       |      |      |
| debris    |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Fractured |       | 1      |       |       |       | 1    | 5    |
| Poly      |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Allergic  |       |        |       | 2     |       |      |      |
| Reaction  |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Pain      | 15    | 1      | 1     |       | 2     | 2    |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Failed    | 1     |        |       |       |       |      | 1    |
| tibia     |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Pain/inf  | 1     |        |       |       |       |      |      |
| lammation |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Cat       |       |        | 1     |       |       |      |      |
| astrophic |       |        |       |       |       |      |      |
| Poly      |       |        |       |       |       |      |      |
| failure   |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Pain      | 5     |        |       |       |       |      |      |
| bilateral |       |        |       |       |       |      |      |
| revisions |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Bearing   |       | 5      |       |       | 1     |      |      |
| dis       |       |        |       |       |       |      |      |
| locations |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Bleeding  |       |        |       |       |       |      | 1    |
| patella   |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Patella/  | 1     |        |       |       |       |      | 4    |
| (avulsion |       |        |       |       |       |      |      |
| )         |       |        |       |       |       |      |      |
| fracture  |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Stiffness | 2     |        |       |       |       |      |      |
| ROM       |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Bearings  |       |        | 1     |       |       |      |      |
| disi      |       |        |       |       |       |      |      |
| ntegrated |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| M         |       |        | 1     |       |       |      |      |
| etallosis |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Porocoat  |       |        |       |       | 1     |      |      |
| s         |       |        |       |       |       |      |      |
| eparation |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Bent      |       |        |       |       |       | 2    |      |
| bearing   |       |        |       |       |       |      |      |
| track     |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Poly      |       | 1      |       |       |       |      |      |
| crumbled  |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Knee      |       | 1      | 2     | 1     |       |      | 3    |
| p         |       |        |       |       |       |      |      |
| rosthesis |       |        |       |       |       |      |      |
| failure   |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Package   |       |        |       |       | 1     |      |      |
| defect    |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Poly      |       |        |       | 1     |       |      |      |
| pitted    |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Implant   |       |        |       |       |       |      | 2    |
| defect    |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| M         | 1     |        | 3     | 1     |       |      |      |
| islabeled |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Malp      |       | 1      |       |       |       |      |      |
| ositioned |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Implant   |       |        | 1     |       |       |      |      |
| did not   |       |        |       |       |       |      |      |
| fit       |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+
| Unknown   |       |        |       |       |       | 1    | 1    |
| revision  |       |        |       |       |       |      |      |
+-----------+-------+--------+-------+-------+-------+------+------+

Although the sponsor provides a list of the MDRs of the one device that
is marketed in the US, similar information is not available for mobile
bearing knees devices in use outside the US. Although literature
articles provide some information, many do not report a complete profile
of the adverse events.

Risks associated with knee surgery include infection, Pulmonary
embolism, gastrointestinal and genitourinary problems. Those associated
with the device are listed above. Risks were grouped into 3 general
categories:

-   Infection

-   Adverse tissue reaction

-   loss or reduction of joint function/revision

The sponsor provided two tables which evaluated patient risk using the
engineering tool, "Failure Modes and Effects Analysis" (FMEA).( Volume
1, Section X, pp. 85-93) The first table, contains the hazards common to
both fixed and mobile bearing knees while the second contains the
additional hazards specific to mobile bearing knees, exclusively.
Potential hazards are listed within each category, as applicable.
Potential effects from those hazards and an initial risk assessment are
presented.

Each hazard in these tables has provided one or more solutions or
actions designed to reduce the potential risk to the patient. An
assessment of the final risk after those solutions/actions are
implemented is presented. In addition, special controls are identified
for each of the hazards.

However, because the mechanics and designs are significantly different ,
the testing demonstrated the safe use of fixed bearing knees may not be
applicable to the mobile bearing designs.

The sponsor contends that many of the identified risks can be mitigated
by material standards, proper device design, labeling and by controlling
the device quality through Good Manufacturing Practices (GMP) Quality
System Regulations (QSR). Numerous FDA guidance documents, ISO
standards, and ASTM standards are available to provide specific guidance
regarding materials, testing and labeling.

There are two risks that the sponsor believes are unique to mobile
bearing knees and not common with fixed bearing knees. These are: the
potential for the mobile bearing to rotate beyond design objectives, and
the potential for greater wear due to an additional articulating surface
are hazards related to the design of mobile bearing knees. For these two
risks, there are no recognized standard testing methods to predict the
modes of failure associated with these risks.

The sponsor also provides the following in support of the
reclassification: (Volume 1, Section X)

• a review of the requirement for various types of special controls,
including a complete listing of FDA guidance

documents, ISO Standards, and ASTM Standards that apply to knee
prostheses.

• A breakout of guidance documents and standards, assigning each to one
of the three general categories of risk

(infection, adverse tissue reaction, and loss or reduction of joint
function).

• Proposed Labeling for mobile bearing knees: a listing of indications,
contraindications, warnings, and adverse

events relevant to mobile bearing knees, including total knees and
unicondylar knees.

Also, included is proposed package insert content that includes
information on total and unicondylar knees.

• Tests and test methods suggested for mobile bearing knees.

In the summary of risks a sponsor is charged with the task of providing
a summary of the following information:

1\. The incidence rate

2\. Cause

3\. Sequelae of the risk

4\. Information demonstrating that the stated risk is not a potential

hazard of the device, if available.

Wear is defined through various bench studies, in-vivo explants are not
presented and the results of bench testing is compared to hip wear data
not knee data. There are studies which review explants and there are
several studies which characterize poly wear in fixed bearing knees
which should be included. The biomechanical characteristics are
summarized in the preclinical review.

**[Known Potential Benefits]{.underline}**

The potential benefits of the device include decreased pain and improved
function; however it is not yet proven that these devices are better or
even completely equivalent to a well functioning fixed bearing knee.
There are few published randomized controlled studies which examine the
outcomes and risks of the fixed and mobile bearing knees side by side.
In some other reports, the survival rate of mobile bearing knees are
slightly lower than fixed bearing knees, the patients are not more
active and the revision rate slightly higher, showing that prevention of
mechanical failure is not higher. The theoretical advantage of a longer
device life in younger, active patients is not proven as most studies
the patients have a mean age of 65 or greater. There are some studies
which have shown that the contact stresses of fixed bearing knees may be
equivalent to those of mobile bearing knees and few explant studies have
validated that reduced wear actually occurs in situ in each type.
Osteolysis similarly has not been shown to be different in the mobile
bearing knees designs. (AAOS instructional course lectures: Callahan, C.
Mobile Bearing Knees: Concepts and Results, 2001.)

That having been said, the sponsor does provide multiple retrospective
and non randomized studies which report good to excellent clinical
results for the majority of study patients.

**[Labeling:]{.underline} (**Section X)

Indications

The data may not support indications for steroid dependent RA or valgus,
varus and flexion deformities. Instability of the knee in general should
be excluded. There is no information to assist a physician to choose a
Mobile bearing knees over a fixed bearing prosthesis, particularly in
the indications statement, as this has not been properly studied

For the unicondylar knee indication should be correctable varus and
valgus deformities is misleading. This should be further clarified that
both should not be present

**\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_**

The memo that follows summarizes the submission and the responses to
FDA's deficiencies from a clinical perspective.

**[Summary]{.underline}**

This reclassification presents data to support the petition for
reclassification of all mobile bearing unicondylar, bicondylar condylar
and tricompartmental knees from Class III to Class II. This includes
clinical data from IDE and outcome studies, peer reviewed journal
articles and meta- analysis comparison analyses between fixed and mobile
bearing systems related to adverse events and effectiveness outcomes.
The sponsor believes that this information provides strong evidence of
the safety and efficacy of mobile bearing knees, and that the risks
associated with these devices are not adequately defined. Before a
decision can be made whether reclassification from Class III (Premarket
Approval Application) to Class II (Special Controls) is justified,
further information and clarification is needed. The sponsor provides
responses to the requests for further information as requested in the
FDA letter dated February 2004.

**[Responses to deficiencies]{.underline}**:

1a. The sponsor provided Appendix 1a with multiple articles on wear,
including back side wear not present in the original petition. It
includes a synopsis of articles on wear defined by these articles.

**[Review]{.underline}: This response is adequate and the sponsor
provides an adequate review of current literature. It serves to
corroborate the premises that:**

-   **there are wear issues for both FBK and MBKs which may lead to
    osteolysis associated with loosening and wear debris**

-   **Wear generated by a total knee prosthesis is dependent on the
    conformity of the components with each other, the type of
    polyethylene used, the patient implanted, and the relative motion
    that occurs at the interface between the components**

-   **The variety of the amount and type of motion at the component
    interfaces is as varied as the types of prosthetic designs.**

-   **Back side wear which occurs with any type of knee prosthetic to
    varying degrees. Studies to detect this risk are few, fraught with
    difficulty and have not been definitive about how to assess this
    risk fully.**

Deficiency 1.b&c.

The sponsor has filled out the table FDA presented as requested to
facilitate review of this reclassification petition. It states the
**representative mobile bearing knees, the biomechanical advantages and
disadvantages, survivorship**\[(survivorship for each mobile bearing
knee device type was calculated by averaging the survival estimate and
mean follow-up reported in the article. Each article included had a
minimum follow-up period of 5 years. If multiple definitions of survival
were included, the most conservative definition was used.) With the
exclusion of this poor performer (Thackeray,UK), all mobile bearing
device groups report \>90% survivorship (note: some of the groups have a
small sample size).\]

Response continued: **Risks and special controls** \[OSMA divided them
into two groups:

1.  risks and special controls that are common to fixed and mobile
    bearing knees, and for which there are no special issues related to
    mobile bearing design features.

> **[Categories]{.underline}**: sterility, biocompatibility, metal
> sensitivity, metal corrosion and separation of the porous coating from
> the metal substrate. These generic risks and related special controls
> were discussed in the original petition and were not included in Table
> 1.c. This is adequate as the sponsor has already provided these
> previously

Risks and special controls includes those that have unique
considerations when applied to mobile bearing knees when compared to the
same special control applied to fixed bearing knees. For example, wear
testing of mobile bearing knees needs to account for additional
articulating surface wear and for rotational movement. Section Appendix
1.c. also includes a section entitled "Special Controls with Unique
Mobile bearing knees Considerations". This text provides descriptions of
each special control, with an explanation of how the control will
provide reasonable assurance of safety and effectiveness. In addition,
the applicable FDA guidance, ASTM and/or ISO

documents are listed for each special control. Where no standard test
method has been defined, OSMA has recommended a test method.

+--------------+---------------+----------------------+---------------+
| **Test**     | **Rationale** | **Current Standard** | **Suggested** |
+--------------+---------------+----------------------+---------------+
| Wear Test    | -Simulate     | ASTM 1715            |               |
|              | sliding       |                      |               |
|              | Rolling and   | ISO 14243            |               |
|              | rotational    |                      |               |
|              | mvmts         |                      |               |
+--------------+---------------+----------------------+---------------+
|              | \- address    | In vitro             | Volume of     |
|              | backside wear | s                    | wear scar     |
|              |               | imulator/gravimetric |               |
|              |               | analysis             | Observed      |
|              |               |                      | changes to    |
|              |               |                      | engraving     |
|              |               |                      | marks         |
+--------------+---------------+----------------------+---------------+
| Particulate  | Determine     | ASTM F-2025          |               |
| analysis     | risk of       |                      |               |
|              | Osteolysis    | ISO 14243-2          |               |
|              | due to        |                      |               |
|              | particulate   |                      |               |
+--------------+---------------+----------------------+---------------+
| Spin Out     |               | None                 | ASTM F-1223   |
| test         |               |                      |               |
+--------------+---------------+----------------------+---------------+
| Tibial Tray  |               | ASTM F-1800          |               |
| Fatigue Test |               |                      |               |
|              |               | ISO 14879-1          |               |
+--------------+---------------+----------------------+---------------+
| Dissociation |               | None                 | Component     |
| /Binding     |               |                      | interlock     |
| Test         |               |                      | Strength      |
|              |               |                      | Testing       |
|              |               |                      |               |
|              |               |                      | SC guidance   |
|              |               |                      | PF & FT M/P   |
|              |               |                      | porous coated |
|              |               |                      | Uncemented    |
|              |               |                      | Prosthesis    |
+--------------+---------------+----------------------+---------------+
| Overhang     |               | none                 | ASTM F-1715   |
| Deformation  |               |                      |               |
| Test         |               |                      | ISO 14243-1   |
+--------------+---------------+----------------------+---------------+
| Contact      |               | None                 | Contact Area  |
| Area/        |               |                      | guidance Semi |
| Stre         |               |                      | Constrained   |
| ssEvaluation |               |                      | knees         |
| (load        |               |                      |               |
| damage)      |               |                      | ASTM F-1715   |
|              |               |                      |               |
|              |               |                      | ISO 14243     |
+--------------+---------------+----------------------+---------------+
| Pa           |               | None                 | Lateral       |
| telloFemoral |               |                      | stability of  |
| Lateral      |               |                      | the PF joint  |
| Stability    |               |                      | testing       |
| test         |               |                      |               |
+--------------+---------------+----------------------+---------------+
| PE Metal     |               |                      | Static        |
| shear        |               |                      | Tensile       |
| Fatigue and  |               |                      | Pull-off and  |
| static       |               |                      | shear Fatigue |
| Tensile      |               |                      | Testing       |
| strength     |               |                      |               |
| test         |               |                      | ASTM F-1672   |
+--------------+---------------+----------------------+---------------+
| Patello      |               | None                 | ASTM F-1715   |
| Femoral      |               |                      |               |
| Contact      |               |                      | ISO 14243-1   |
| Stress(load  |               |                      |               |
| Damage and   |               |                      |               |
| Patellar     |               |                      |               |
| wear         |               |                      |               |
+--------------+---------------+----------------------+---------------+
| Wear test of |               | None                 | ASTM 1715     |
| stop         |               |                      |               |
|              |               |                      | ISO 14243-1   |
+--------------+---------------+----------------------+---------------+
| Labeling,    |               | None                 | 21 CFR        |
| Surgical     |               |                      | 801,820 and   |
| Technique    |               |                      | ISO 6018      |
| surgeon      |               |                      |               |
| training     |               |                      |               |
+--------------+---------------+----------------------+---------------+

d\. The sponsor provides Table 1.d. (see Appendix 1.d.) which provides a
summary comparing the various mobile bearing knee device groups with
fixed bearing devices. And Supplement 1.d., which lists the clinical
outcome details of each study that was utilized to provide the data in
table 1.d.

**[Review]{.underline}: The sponsor has provided the information as
requested, however because the sample size is small no statistical
conclusions can be reached. It is note worthy that only few mobile
bearing knee designs are approved in the US and those are the subject of
the reclassification petition.**

**This table overstates the revision rate of Fixed Bearing Knees. In the
recent NIH consensus the overall prosthesis failure rate is given as 1%
per year or 10% at 10 years. It is worth noting that the revision rate
of mobile bearing knees is not less than that of fixed bearing
devices**.