Multicenter Clinical Observation Using the Cementless Version of the POLARSTEM
Conditions: Osteoarthritis
Sponsor: Smith & Nephew, Inc.

Multicenter Clinical Observation Using the Cementless 
Version of the POLARSTEM™ 
 
SUMMARY ..................................................................................................................... 2 
1 
STUDY OBJECTIVES ............................................................................................... 3 
1.1 
Background ................................................................................................ 3 
1.2 
The POLARSTEM™ ......................................................................................... 3 
1.3 
Objectives .................................................................................................. 4 
2 
STUDY DESIGN ..................................................................................................... 5 
2.1 
Patient selection .......................................................................................... 5 
2.2 
Sample size consideration............................................................................ 6 
2.3 
Study duration ............................................................................................ 6 
2.4 
Pseudonymisation of patient identifiable information ....................................... 6 
3 
STUDY METHOD ................................................................................................... 7 
3.1 
General ...................................................................................................... 7 
3.2 
Postoperative rehabilitation .......................................................................... 7 
3.3 
Follow-up .................................................................................................... 7 
3.4 
Complications/adverse events/lost-to follow-up ............................................. 8 
3.5 
Patient recruitment ...................................................................................... 8 
4 
DESCRIPTION OF THE DEVICES .............................................................................. 9 
4.1 
Implants ..................................................................................................... 9 
4.2 
Instruments ................................................................................................ 9 
5 
ETHICAL AND LEGAL ASPECTS ............................................................................ 10 
5.1 
Ethical aspects .......................................................................................... 10 
5.2 
Legal aspects ............................................................................................ 10 
6 
PARTNERS .......................................................................................................... 11 
6.1 
Study sponsor and monitor ........................................................................ 11 
6.2 
Investigators ............................................................................................. 11 
6.3 
Publication policy ...................................................................................... 12 
7 
SIGNATURE ........................................................................................................ 13 
8 
REFERENCES ....................................................................................................... 14 
 

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SUMMARY 
 
Objective: Validation of the POLARSTEM™ as state-of-the-art implant in terms of radiographic, 
clinical performance and long-time survivorship. 
 
Study design: Prospective study  
 
Study population: Total of 225 patients in 3 different sites  
 
Intervention (if applicable): Implantation of a total hip prosthesis  
 
Main study parameters/endpoints: Radiographic: radiolucent lines, osteolysis, hypo- or 
hypertrophy; implant loosening or migration; Clinical: Harris Hip Score and HOOS Score 
 
Nature and extent of the burden and risks associated with participation, benefit and 
group relatedness: Patients will benefit without restriction from their total hip prosthesis. 
Patients enrolled in this study will receive the same operation and the same follow-up 
treatments as patients not enrolled. Therefore, no additional risks are expected. 
 
 
 
 
 
 
 

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1 
STUDY OBJECTIVES 
1.1 Background 
Total hip arthroplasty (THA) has been an established treatment procedure for patients 
suffering osteoarthritis of the hip and other joint diseases. However, THA alters the 
distribution of mechanical forces around the hip joint leading to bone remodeling related to 
implant design and mechanical properties as implied by Wolff’s law. According to this law, an 
implantation of a femoral prosthesis induces a reduction of the proximal compressive 
stresses and a reactive loss of the proximal femoral bone mass. Although stress shielding 
has been described as clinically irrelevant with some stem designs (i.e., double-tapered form) 
[1], others suggest that this phenomena can compromise the implant stability and thus the 
clinical outcome of a THA and may predispose to loosening, migration as well as 
complications of the implant during revision [2, 3]. Furthermore, proximal radiolucent lines 
may provide wear particles (e.g., polyethylene) the possibility to migrate along the bone-
implant interface, enlarging the risk of osteolytic processes [4]. 
Hydroxyapatite (HA) coatings have been widely used in THA due to their osseoconductive 
properties [5, 6]. HA on proximal stems have been shown to improve osseointegration, thus 
facilitating load transmission in the metaphysal part of the femur and hence reduced stress 
shielding. An improved osseointegration may also function as a barrier to migration of wear 
debris to the bone-implant interface, eventually leading to reduced osteolysis and increased 
implant long-term survival. 
 
1.2 The POLARSTEM™ 
The POLARSTEM™ is a double-tapered stem with a large proximal part and a short and slim 
distal end and it is forged from a Ti-6Al-4V alloy. The neck of the POLARSTEM™ is mirror-
polished to reduce the risk of insert damage during impingement. The bone-contacting part of 
the stem is coated with a ground layer from porous titanium (150 μm) and covered with a HA-
coating (80 μm) offering excellent primary stability and improved osseointegration. 
Furthermore, the POLARSTEM™ exhibits proximal grooves perpendicular to the internal curve 
and to the average load direction to reduce the risk of implant subsidence. For increased 
rotational stability the stem also features distal grooves reversed to the rotational direction. 
 

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Fig. 1: Cementless version of the POLARSTEM™ made from a Ti-6Al-4V alloy exhibiting its 
characteristic grooves on the hydroxyapatit (HA)-coating (see text for details). 
 
 
1.3 Objectives 
The goal of this multicenter clinical observation is to validate short-, mid-, and long-term 
outcome (efficacy and safety) of the POLARSTEM™. 
 
Efficacy evaluations 
 
Evaluation of function, range of motion (ROM) and pain as assessed by Harris Hip Score, 
Hip disability and osteoarthritis outcome score (HOOS) [7, 8], an extension of the Western 
Ontario and McMaster Universities Osteoarthritis Index (WOMAC). 
 
Radiographic changes as defined by radiolucent lines, osteolysis, hypo- and hypertrophy, 
implant loosening or migration  
 
Safety evaluations 
 
Intra- and perioperative device-related adverse events (AE) and complications up to 
discharge  
 
Postoperative AE up to 10 years 
 
Long-term survivorship will be calculated according to Kaplan-Meier with stem revision due to 
any reason as endpoint.  

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2 
STUDY DESIGN 
This is a prospective long-term multicenter clinical observation study using the cementless 
version of the POLARSTEM™. Overall, a minimum of 225 patients will be enrolled in 3 sites. 
Each site will enroll the patients consecutively; the number of patients per site will be defined 
together with each investigator. 
 
2.1 Patient selection 
Patients enrolled in this multicenter clinical observation will have at least one of the indications 
listed below and meet all of the inclusion criteria. Patients meeting any of the exclusion criteria 
are not eligible for this study. 
Indications 
 
Primary or secondary coxarthrosis 
 
Rheumatoid arthritis 
 
Developmental dysplasia of the hip (Crowe type I and II) 
 
Fracture or avascular necrosis of the femoral head 
 
Inclusion criteria 
 
Patient has no general medical contraindication to surgery  
 
Informed consent to participate in the MCO signed by the patient  
 
Routine radiographic assessment is possible  
 
Patient is likely to comply with study follow-up requirements 
 
Primary total hip replacement (THR) to the affected side, unilateral or bilateral 
 
 
Exclusion criteria 
 
Previously failed endoprosthesis and /or THR components in relevant hip 
 
History of infection in the affected joint; systemic infections 
 
Grossly insufficient femoral or acetabular bone stock in the involved hip 
 
Charcot joint disease or other severe neurosensory deficit 
 
Severe spinal disorders 
 
Age of patient at date of surgery > 75 years 

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 
High comorbidity 
 
Cemented acetabular cup 
 
2.2 Sample size consideration 
Sample size estimations have been made on the assumption that for a valid statistical data 
analysis according to Kaplan-Meier, at least 100 implants surviving 10 years are necessary. 
Over a period of 10 years, a drop-out rate of 30% should be considered. Therefore, 150 initial 
implantations are needed in each group.  
 
2.3 Study duration 
It is expected to enroll all patients within 12 months. Each patient will be called for follow-up 
investigations after 3 months, 1 year, 3 years, 5 years, and 10 years.  
 
2.4 Pseudonymisation of patient identifiable information 
Patients’ data are pseudonymized using a consecutive number according to their study 
enrolment. 

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3 
STUDY METHOD 
3.1 General 
Patients’ pre-operative status, surgical procedure as well as clinical and radiological outcome 
will be documented by means of Case Report Forms (CRFs) that are provided by the study 
sponsor. CRFs will be filled in the investigator or specially assigned hospital personnel who 
have been trained for the study. Completed CRFs are faxed from the site to the sponsor 
immediately upon completion. Case Report Forms are the basis for further data evaluation. 
Pain, function, gait, range of motion (HHS) and radiographic status determinations are made 
pre-operatively and at each post-operative examination. Radiographic analysis will be done 
on standard AP and lateral view X-rays.  
Pre-and postoperative HOOS questionnaires are filled in by the patients themselves. Patients 
must have the possibility to complete the forms on their own, without any external influence. 
This means patients should have the possibility to take the questionnaire home and return it 
to the hospital at a later date. 
 
3.2 Postoperative rehabilitation 
Postoperative rehabilitation is carried out according to each hospital’s standard procedure. 
 
3.3 Follow-up 
The follow-up schedule is shown in table 1. 
Table 1: Time windows for investigations 
 
Time-window 
HHS/HOOS 
Clinical 
Radiographic 
Preoperative 
45–0 days 
X 
X 
- 
3 months 
10–14 weeks 
X 
X 
X 
1 year 
11–13 months 
X 
X 
X 
3 years 
36-38 months 
X 
X 
X 
5 years 
60–63 months 
X 
X 
X 
10 years 
120–123 months 
X 
X 
X 
 

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3.4 Complications/adverse events/lost-to follow-up 
Complications and adverse events are noted at each follow-up interval. For completed 
observations due to death of the patient, explantation of the device or patient’s address 
unknown the latest status will be recorded as an endpoint. Patients will be considered lost to 
follow-up after they have missed two visits and all attempts to locate and evaluate them have 
failed. Patients who refuse to attend follow-up or patients unable to attend follow-up will be 
assessed by telephone if possible. Minimal data concerning the implant status should be 
acquired by telephone. 
 
3.5 Patient recruitment 
Ethical approval is required according to the local regulations of the participating countries. 
Patients will be screened according to inclusion and exclusion criteria by the investigator. If 
inclusion criteria are met, patients will be informed about the observation accompanying the 
surgical procedure. Patients are enrolled in this observation only after they have given a 
written informed consent. The Patient enrolment has to be carried out within a period of 12 
months.  
 

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4 
DESCRIPTION OF THE DEVICES 
4.1 Implants 
In this study, the cementless POLARSTEM™ will be used in combination with a well 
documented, cementless acetabular component from Smith & Nephew Orthopaedics AG.  
 
4.2 Instruments 
The participating surgeons will only use instruments supplied by Smith & Nephew 
Orthopaedics AG for the implantation of the POLARSTEM™. All instruments will be used 
conform to the instructions of the manufacturer. 
 

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5 
ETHICAL AND LEGAL ASPECTS 
5.1 Ethical aspects 
This clinical trial will be performed in agreement with the “Declaration of Helsinki” (Version of 
1994) and ISO 14155. 
Participation in this study is voluntary and it is the patients’ right to stop the participation at 
any time without any declaration of reasons. 
Patients will be informed orally and in written form about the study, its risks and benefits and 
their signed informed consent will be recorded. 
 
5.2 Legal aspects 
Approval from ethics committee is required prior any patient recruitment. 
Patients’ name and other confidential information are subject to confidential medical 
communication and patients’ data will be made fully anonymous for analysis purposes.  
For monitoring purposes (through notified bodies or the study monitors), it might be necessary 
to identify the patients’ name and to check original medical records to ensure proper study 
procedure. For this case the patient has given his signed informed consent. 

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6 
PARTNERS 
6.1 Study sponsor and monitor 
Smith & Nephew Orthopaedics AG 
Oberneuhofstrasse 10d 
6340 Baar 
Switzerland 
 
6.2 Investigators 
Principal Investigator 
Dr. med. Turgay Efe 
Klinik für Orthopädie und Rheumatologie 
Universitätsklinikum Giessen und Marburg 
Baldingerstrasse 
35043 Marburg 
Germany 
 
Further Investigators 
Site 2 
Dr. med. Marc Zumstein 
Chefarzt 
Orthopädische Klinik  
Kantonsspital Aarau 
CH-5001 Aarau 
 
Site 3 
Prof. Dr. med. R.E. Willburger 
Leitender Arzt der Abteilung für Rheumaorthopädie im St. Elisabeth-Hospital 
Orthopädische Universitätsklinik 
44787 Bochum 
 

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6.3 Publication policy 
The results of all study sites will be pooled regularly into an overall-publication and submitted 
to a peer-reviewed anglophone journal. The publication schedule will be defined by the group 
of investigators. The authorship is defined as follows: 
 
Johannigmann K; Graven F; Dabis E; Peterlein CD, Efe T, Schofer M, Zumstein M, Willburger 
RE 
 
Any change to this authorship requires mutual written agreement from the INVESTIGATORS 

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7 
SIGNATURE 
I agree to conduct this clinical study in accordance with the design and specific provisions of 
this protocol. 
 
 
 
 
 
Investigator Signature 
 
 
 
 
_______________________________ 
 
 
 
 
Date of Signature 
 
 
 
 
_______________________________ 
 
 

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8 
REFERENCES 
 
[1] 
Pospischill M, Knahr K. Cementless total hip arthroplasty using a threaded cup and a 
rectangular tapered stem. Follow-up for ten to 17 years. J Bone Joint Surg Br. 2005 
Sep;87(9):1210-5. 
[2] Jacobs JJ, Sumner DR, Galante JO. Mechanisms of bone loss associated with total hip 
replacement. The Orthopedic clinics of North America. 1993 Oct;24(4):583-90. 
[3] Roberson JR. Proximal femoral bone loss after total hip arthroplasty. The Orthopedic 
clinics of North America. 1992 Apr;23(2):291-302. 
[4] Santavirta S, Hoikka V, Eskola A, Konttinen YT, Paavilainen T, Tallroth K. Aggressive 
granulomatous lesions in cementless total hip arthroplasty. J Bone Joint Surg Br. 1990 
Nov;72(6):980-4. 
[5] Christ R, Fennema P, Kortemeier S, Hagena FW. Optimization of osseous integration of 
the SL-Plus stem with a proximal hydroxyapatite coating. In: Friederich NF, Santore RF, 
eds. 25 Year of Biologic Fixation Prof Dr K Zweymüller. München: Urban & Fischer 2006. 
[6] Effenberger H, Graf R, May M, Lojpur M, Imhof M, Lintner F. Anatomically adapted, HA 
coated SBG stem--ten years of successful implantation. Biomed Tech (Berl). 2004 
Oct;49(10):290-4. 
[7] Harris WH. Traumatic arthritis of the hip after dislocation and acetabular fractures: 
treatment by mold arthroplasty. An end-result study using a new method of result 
evaluation. The Journal of bone and joint surgery. 1969 Jun;51(4):737-55. 
[8] Klässbo M, Larsson E, Mannevik E. Hip disability and osteoarthritis outcome 
score. An extension of the Western Ontario and McMaster Universities 
Osteoarthritis Index. Scand J Rheumatol. 2003;32(1):46-51