Kinematic Analysis: Posterior Stabilized, Fixed Bearing Total Knee Arthroplasty With Attune Knee System - Phase 2
Conditions: Total Knee Arthroplasty, Osteoarthritis
Sponsor: The University of Tennessee, Knoxville

 
 
 
 
Kinematic Analysis: Posterior Stabilized, Fixed-
Bearing TKA with Attune Knee System 
University of Tennessee 
Adrija Sharma, Ph D 
2-20-2019 
 

INTRODUCTION 
A better understanding of knee joint kinematics for patients implanted with total knee 
arthroplasties (TKAs) to help improve designs of prostheses that most closely approximates the 
normal knee kinematics. TKA surgery inevitably and irreparably alters the complex geometry and 
the soft tissue interactions occurring at the knee joint. Moreover, TKA surgery is always 
performed on non-normal, non-healthy knee joints. Therefore, not surprisingly, kinematic 
profiles observed after TKA have been reported to vary considerably than those observed in 
normal knees. Specifically, posterior stabilizing (PS) knees have been found to be associated with 
lower amounts of posterior femoral rollback, higher occurrence of reverse axial rotation and 
increased amount of condylar lift-off. It is important to focus on these previously reported 
abnormalities and design newer PS TKA which can restore kinematics (at least in nature, although 
not necessarily in overall magnitudes due to design constraints) closer to that observed in normal, 
non-implanted knees. This is would ensure optimal operating conditions for the PS TKAs while 
inside the body so that they can further improve function and can last a long time without the 
need for immediate revision. 
The Attune™ PS fixed bearing knee system has incorporated subtle changes in its design to 
address these issues. However, in order to understand if this design is able to effectively restore 
kinematics in the implanted knee, further in vivo analysis is necessary. With this aim in mind, this 
study is designed to analyze the in vivo kinematics observed in patients implanted with the 
Attune™ PS TKA. 
DESCRIPTION AND SOURCE OF RESEARCH PARTICIPANTS 
In vivo knee kinematics will be assessed for 30 subjects who have been implanted with a DePuy 
Attune PS TKA by Dr. Thomas Fehring, Dr. J. Bohannon Mason, or Dr. William Griffin recruited 
from their practices at OrthoCarolina, PA, 2001 Vail Avenue, Suite, Charlotte, NC 28207; this is 
the location from which all participants for this study will be recruited. Subjects will have the 
DePuy Attune PS fixed bearing TKA, will have a well-functioning prosthesis, and be judged 
clinically successful.  Deciding which patients received this specific kind of implant was up to the 
discretion of Drs. Fehring, Mason, or Griffin, according to their professional opinions. The 
determination as to which type of implant each patient received is outside the scope of this 
particular study. Subjects will already have the knee implants and must be at least three months 
post-operative.  
We will use the following criteria to recruit implanted participants for this study: 

1. 
Subjects must be at least three (3) months post-operative with no other surgical 
procedures conducted within the past six months. 
2. 
Subjects must be between 30-80 years of age. 
3. 
Potential subjects will have a body weight of less than 280 lbs. 
4. 
Participants must have Body Mass Index (BMI) >18.5 and <35. 
5. 
Pregnant or potentially pregnant females will be excluded from the study. To satisfy 
radiation protocol, each female subject will be asked if she is pregnant, or possibly could be 
pregnant. A pregnant person will not be allowed to participate in the study. 
6. 
Must have of Knee Society score (KSS) greater than 80. [Acquired after consenting.] 
7. 
Potential subjects should have good-to-excellent post-operative passive flexion with no 
ligamentous laxity or pain. 
8. 
Participants must be able to walk on level ground without aid of any kind, perform a ramp 
descent, and a deep knee bend (DKB), all without assistance. 
9. 
All potential subjects will have a DePuy Attune PS Fixed Bearing TKA.  
10. 
Patients from the physician’s list who do not meet the study requirements will not be 
considered.  
11. 
Patients must be willing to sign the Informed Consent (IC) and HIPAA forms to participate 
in the study.  
All participants will be between the ages of 30 and 80 years old, which is typical for a patient 
having a TKA. Since the average age of an implant patient is 70 years, it is unlikely that any female 
subjects will be pregnant. To satisfy radiation protocol, each female subject will be asked if she is 
pregnant, or possibly could be pregnant. A pregnant person will not be allowed to participate in 
the study due to the radiation exposure from use of fluoroscopy in data collection.  
The U.S. Department of Health and Human Service’s publication Vital and Health Statistics from 
May of 2013 cites the “a standard age range (often 16-49)” commonly used to define “child-
bearing age” (1), so researchers will use that age range to determine whether or not any female 
potential participants are of “child-bearing age.” If it is determined that one of the potential 
participants’ age falls within this particular range, the female subject will be asked to submit to a 

urine test or provide documentation that she cannot become pregnant. If the potential subject is 
pregnant or refuses the test, she is not eligible to participate in the study. 
METHODS AND PROCEDURES 
After Dr. Thomas Fehring, Dr. J. Bohannon Mason, or Dr. William Griffin satisfactorily evaluated 
patients with the DePuy Attune PS TKA from their practices at OrthoCarolina PA that fulfilled the 
study criteria for participation, the OrthoCarolina Research Institute (OCRI) staff sent 
recruitment letters to eligible patients that explained the study, inviting them to participate. The 
recruitment letter requested that those eligible patients that wished to participate call Alexis 
Ready to inform her of their willingness to participate and schedule a visit to OCRI to sign the 
IC/HIPAA forms and demographic information forms for travel and payment. The surgeon will 
administer the KSS and KOOS surveys to confirm eligibility requirements.  
Subjects traveled to Knoxville to undergo the fluoroscopy procedure using a fluoroscopy unit at 
either the University of Tennessee using a mobile fluoroscopy unit or to Abercrombie Radiology. 
Subjects will be asked to perform the same three activities under fluoroscopic surveillance using 
the fluoroscopy unit: (1) level walking, (2) ramp descent, and (3) a DKB. Subjects will be video-
recorded from the waist down while performing the activities while under fluoroscopy 
surveillance.  
The study activities are: (1) level walking (gait), (2) ramp down, and (3) a DKB. 
1. 
Normal Gait  
a) 
The subject will begin standing at rest with her/his knee in question slightly forward. 
b) 
The subject will take a lead step with her/his knee in question and proceed to walk at a 
comfortable pace for approximately 5 paces, or until instructed to stop. 
2. 
Ramp Down 
a) 
The subject will begin standing at rest with her/his knee in question slightly forward at the 
top of the ramp. 
b) 
The participant will be asked to take a lead step with her/his knee in question down the 
ramp until s/he reaches the bottom of the ramp (approximately 3 steps). 
3. 
Deep Knee Bend  

a) 
The participant will be asked to stand with his/her examined knee close to the image 
intensifier at full extension with his/her feet staggered (examined knee in front). 
b) 
The participant will flex her/his knee until it has reached maximum flexion.  
These activities will be performed without the aid of handrails, as walking without aid of any kind 
is one of the criterion for participation in the study; however, one of the researchers will be ready 
and in close proximity to assist each subject during all activities in case the participant requires 
help. This precaution will be practiced for all participants, regardless of physical wellbeing, age or 
prior results; no assumptions will be made as to any participant’s capabilities.  
Ground reaction force (GRF) data will be acquired simultaneously by force plates embedded into 
the platforms on which participants perform the activities; it will be measured, captured and then 
used as input into a mathematical model, allowing for determination in vivo forces at the knee. 
The speed level of each trial will be based on the comfort level of the subject. The fluoroscopic 
images will be stored digitally for subsequent analysis on secure servers and workstations at UT. 
In vivo knee kinematics will be assessed for all 30 subjects. 
There will be at least two UT researchers present, as well as the study PI, Dr. Sharma, to conduct 
the fluoroscopic evaluation. A Radiation Technician (RT) will perform the actual fluoroscopy 
procedure, following the subjects’ implanted knee with the unit as the activities are performed; 
only the knee joint (from the fluoroscopy machine) will be recorded on the fluoroscopy footage. 
The participant will be allowed to rest as necessary and be instructed to stop the activity at the 
first sign of pain. The UT researchers, graduate research assistants (GRAs) will be present, 
although they will not perform the actual fluoroscopy procedure. They will be present during the 
fluoroscopy procedure to walk subjects through the activities, answer any questions that may 
arise, ensure data collection equipment is set up as needed and serve as consultants to the RT.   
Subjects will have the opportunity to ask any questions they may have during the scheduled data 
collection visit. All subjects will be informed that they do not have to participate and are free to 
leave if they wish. Participation is entirely voluntary.  
Participants will be asked to practice the activities to ensure they can comfortably complete them 
and experience no pain with the fluoroscopy machine off (no radiation). Age, weight and other 
eligibility requirements will be verified prior to fluoroscopy to ensure eligibility using the study’s 
Inclusion Criteria Recruitment/Enrollment form.  If a subject does not meet the inclusion criteria 
just prior to fluoroscopy, s/he will not be tested. The KSS score will be confirmed with subject 
medical data from OCRI prior to beginning the fluoroscopy procedure.  

Multiple trials of each activity may be conducted to ensure usable images have been acquired to 
complete the study. Radiation time will be kept as low as reasonably achievable (ALARA) and will 
not exceed two minutes. The RT will start the fluoroscope just prior to the subject beginning each 
activity trial and will stop the fluoroscope immediately after the subject completes each activity 
trial to ensure that the subject is not exposed during idol periods. On-time will be recorded on the 
subject’s IC, as well as any output the fluoroscopy unit is able to provide. 
The fluoroscopic footage for these activities will be stored on digital video files on a secure 
computer workstation and stored securely by UT researchers. It will then be uploaded onto the 
secure CMR database by these researchers. Once the data has been uploaded, identifiers are 
removed from the data automatically by the database, and a study and subject-specific identifier 
will be assigned to each subject. Data such as dates of birth and surgery are converted to number 
of months by the database. Only the converted data with study and subject-specific identifiers are 
what are available to UT researchers after the initial upload of data.   
Implanted Knee Analysis 
Using a model-fitting approach, the relative pose of knee implant components will be determined 
in three-dimensional (3D) from a single-perspective fluoroscopic image by manipulating a 
computer-aided design (CAD) model in 3D space. The 3D scene of the fluoroscopic unit is virtually 
recreated on a computer.  The scene consists of a light source (x-ray), an image plane on which to 
project the fluoroscopic image (image intensifier), an area to manipulate a 3D model (subject 
area), and a camera to view the entire scene.  
Individual fluoroscopic frames at specified degrees of flexion for each activity will be digitized. 
The images will be projected onto the image plane and the corresponding implant models added 
to the scene. The operator will manipulate the models in an initial starting position, and a global 
optimization algorithm will determine an accurate fit. The correct fit will be achieved when the 
silhouettes of the femoral and tibial implant components best match the corresponding 
components in the fluoroscopic image. The pose of each component will be recorded and 
measurements of interest will be extracted using a CAD modeling program. For deep flexion 
activities, the process will be performed at full extension, 30° of knee flexion, 60° of knee flexion, 
90° of knee flexion, and 120° of knee flexion (if subject achieves this amount).  For the walking 
activity, the process will be performed at heel-strike, toe-off and two other instances during 
stance-phase.  The following femoro-tibial kinematic parameters will be investigated under in 
vivo conditions and reported: 

1. 
Location of the contact points  
2. 
Amount of translation and axial rotation 
3. 
Weight-bearing range-of-motion 
4. 
Lift-off 
SPECIFIC RISKS AND PROTECTION MEASURES 
1. 
Fluoroscopic Procedures 
As with every clinical study, there may be some risks.  However, doses of radiation exposure 
received will be much lower than those known to produce detectable health effects. Previously 
reported literature shows that fluoroscopy-based procedure (angiography) on the lower limb 
result in a typical effective dose of 0.83 mSv per min (0.083 rem per min) (Verdun ).  Mettler, et 
al have reported that the typical effective dose for a conventional knee procedure is 0.005 mSv 
(0.0005 rem).  According to either estimate, the additional risk of a fluoroscopic procedure 
involving the knee ranges between "Negligible" to "Low" for a 2 minute exam (Verdun).  A 
previous fluoroscopy TKA study conducted at another hospital with a 2 minute on-time limit 
shows that the average effective dose was 0.14 mSv (0.014 rem) with a maximum dose of 0.27 
mSv (0.027 rem).  The additional risk for all subjects in this previous study would be considered 
"Negligible".  To account for subject variability and differences in imaging techniques, all subjects 
enrolled in this study will receive fewer than 2 rem.  Two rem is considered "Very Low" risk.  It is 
unlikely that anyone in this study will approach the 2 rem limit. Since the fluoroscopy data will be 
collected in one session, there will only be one day in which the participants will be exposed to 
this amount of radiation. 
In conclusion, a participant who will be fluoroscoped for less than two minutes will be exposed to 
a maximum amount of only 2.0 rems of radiation. This means that the maximum total exposure 
rate will be less than 2 rems per subject for the entire experiment.  The participant's knee joint 
will be fluoroscoped using minimal risk levels of radiation according to published literature.  
The participant has the right to stop the procedure at any time; researchers or the RT can end the 
procedures at any time if they feel the participant is at risk, but the participant can choose to 
remain in the study if s/he feels that there is no risk to her/his surgical procedure or recuperation.  
We are estimating a total maximum time of 1 hour to permit the subject time to complete the IC 
form, ask any questions s/he may have, practice the activities or repeat any activities that could 
not be completed, and collect all necessary fluoroscopy data from each subject.   

2. 
Participant Confidentiality  
The investigator will ensure subject confidentiality to the extent that is permissible by law is 
maintained throughout the study and after. Complete confidentiality cannot be guaranteed. 
Computer Database: 
On the day of data collection, the list of subject names will be given to UT researchers and 
researchers will use this to generate subject-specific identifiers; surgeon study staff will be 
provided with this list of subject names and corresponding generated identifiers. These assigned 
identifiers will be uploaded into an excel spreadsheet created by UT researchers. Surgeon study 
staff will be aware of each subject’s respective identifier from the table provided to them on the 
day of data collection after UT researchers generate the subject-specific identifiers. They will 
upload the PHI from subject medical files into the excel spreadsheet and transmit the document 
back to UT researchers via UT’s secure email transmission known as the Vault 
https://vault.utk.edu/. No names exist on the spreadsheet. 
After the study data has been entered into the spreadsheet by the surgeon’s office, researchers 
present during data collection or appointed by Dr. Sharma will upload the subject data, including 
PHI, fluoroscopy, and video footage, into the CMR digital data collection. Consequently, student 
researchers in CMR who assist in data analysis cannot access subject-specific information. All 
participant queries (lookups) generate the participant identification number (the ID generated by 
UT researchers) and no subject identifiers. No identifiable images exist in the database. This study 
data will be kept indefinitely on the secure CMR database for possible future research (with the 
permission of each participant – requested in the IC). In the case of participant withdrawal from 
the study, the Revocation of Consent that the participant will be asked to complete requests that 
the participant indicate whether or not data collected prior to withdrawal may be used for data 
analysis purposes, or if it should be removed from the CMR data collection completely and 
destroyed. 
Hard Copy 
In compliance with HIPAA regulations, all participants will have their identities withheld from all 
public files. Individuals not indicated as Investigators below will have access to participant 
information and they will sign pledges of confidentiality.  
Clinical Observations 

There are no clinical observations made during this data collection or from the images obtained 
through data collection. UT researchers do not require a report of any kind. There will be no 
radiology report generated for this procedure conducted as a result of this study. Therefore, no 
RT will review such a report for the procedures, which would be the only way such a “significant 
problem” would be determined. It is not anticipated that the imaging collected during this study 
would potentially provide benefit to specific subjects by influencing a patient’s treatment plan. 
Protected Health Information/Medical Record Data 
OCRI staff will send subjects’ clinical information from their medical records – protected health 
information (PHI) – to CMR researchers to aid in the interpretation of the results and correlate 
clinical outcomes versus kinematic results, although only researchers present during data 
collection, appointed student researchers chosen by Dr. Sharma to lead the study, Investigators 
and respective staff will have access to PHI; individuals not noted as Investigators will sign 
confidentiality statements. OCRI staff will send subject data (with subject-assigned IDs) to CMR 
researchers by inputting data into an excel spreadsheet that will be transferred back to UT 
researchers via UT’s secure email known as the Vault https://vault.utk.edu/. The 
clinical/demographic information acquired from the medical records with participant 
authorization obtained via HIPAA form will include:  
• Age or date of birth 
• Body weight  
• Range-of-motion  
• Previous medical assessments that are not a part of this particular research study 
• Post-operative time and any other conditions that may alter the kinematic results, such as back 
problems, ankle fusion, or contra-lateral knee problems  
• Pre-operative Knee Society score 
• Knee implant information 
This information can be used to rule out any unique kinematic patterns. This information will 
only be used by the UT researchers and will not be provided to any other source.  
Researchers would like to retain this de-identified data in our secure database so as to continue 
to add relevant, current data to our digital collection to help us work with manufacturers in the 
future to create better implants that last longer and will not require revision surgery, as many 

TKAs currently do. Participants will be asked if their de-identified data may remain a part of the 
CMR digital data collection for use in future studies in the IC. Likewise, should a subject choose 
to withdraw from the study, s/he will have the option as to whether or not de-identified data 
collected from them at the point of withdrawal may be used for data analysis or if their 
information should be provided to them and destroyed from CMR records on the Revocation of 
Consent form they will be asked to complete.  
Two separate tables will be created for this study which will be stored securely on the CMR server, 
the first of which will contain the participants’ names and assigned ID numbers. This table will 
only be accessible by Dr. Sharma after the initial study data has been uploaded onto the secure 
CMR database.  
BENEFITS 
The potential benefits from this study include, but are not limited to: 
• 
Determination as to whether or not the DePuy Attune PS TKA more closely represents the 
natural knee. 
• 
Future implant design improvements based on the kinematic findings. 
• 
New and advanced surgical techniques for TKA based on the results.  
• 
Participants will receive a set stipend agreed upon by sponsor.  
• 
There is no intention of any direct benefit to participants of the study. They will be able to 
see their implant on the video monitor. 
Remuneration  
Participants will be compensated for their participation in the amount of a $300.00 set stipend. 
The $300.00 stipend will be paid by the University of Tennessee and was included in the budget 
for the proposal, agreed upon by sponsor and University.  
One night of lodging will be booked for each subject according to the scheduled time of their 
appointment. Lodging expenses will be direct billed to the University; any additional lodging will 
be at the expense of the participant. Participants will be reimbursed for mileage at a rate of $.56 
per mile, maximum of 550 miles/$308.00 [roundtrip]; mileage reimbursement will be calculated 
by using their home address. Subjects will also receive up to $75.00 per day for meals expenses 
for two days (maximum of $150.00 for both days), although in order to acquire reimbursement, 
itemized receipts for the meals must be submitted to UT. No meals expenses will be processed 

without itemized receipts, as this documentation is necessary in order for DePuy to reimburse UT 
for these costs. It is the responsibility of the subject to acquire itemized receipts. If itemized 
receipts are not submitted, per diem rates do not apply and will not be processed.  
Investigator Funding 
DePuy Synthes, the sponsor of this study, has approved and agreed to a specific amount of 
compensation for conducting this particular research study with Dr. Sharma at the University of 
Tennessee which has been deposited into an R’ account (for research) which will be overseen by 
Dr. Sharma. There is a contract agreement between the University of Tennessee and OCRI for the 
OCRI staff’s participation in this study. The first page of the IC indicates a brief allocation of funds 
by the sponsor to the PI.  
METHODS FOR OBTAINING "INFORMED CONSENT" FROM PARTICIPANTS 
After subjects were recruited and enrolled by OCRI using the approved recruitment materials and 
study documents, they were asked to complete the KSS and KOOS surveys and the necessary 
forms for their stipend to be processed for payment through UT. They were given the opportunity 
to ask any questions about the study.  
The copies of IC/HIPAA forms completed prior to data collection will be maintained in a locked 
cabinet at the University of Tennessee and accessible by only approved study personnel. The 
forms will be securely maintained through any future use of protected data (at the very least three 
years) at the University of Tennessee 
STATISTICAL ANALYSIS PLAN 
Basic descriptive statistics (mean, standard deviation and range) would be analyzed for the 
condylar movement, axial rotation and maximum ground reaction forces for the all the activities.