A Multi-center Prospective Randomized Control Trial to Compare Two Articulating Bearing Surfaces, Ceramic-on-metal and Metal-on-metal as Used in Cementless Primary Hip Arthroplasty
Phase: NA
Conditions: Osteoarthritis
Sponsor: Zimmer Biomet

 
 
COM vs. MOM 
Protocol number: BMETEU.CR.EU11 
Document date: 23-Sep-2008 
 
1 
 
 
 
 
 
 
 
A Multi-Centre Prospective Randomised 
Control Trial to compare two articulating 
bearing surfaces, ceramic-on-metal and metal-
on-metal using 38 mm M2a acetabular cup, as 
used in cementless primary hip arthroplasty 
 
 
Protocol number: BMETEU.CR.EU11 
 
NCT number: NCT00754520 
 

 
 
COM vs. MOM 
Protocol number: BMETEU.CR.EU11 
Document date: 23-Sep-2008 
 
2 
 
Complete Protocol 
Title 
A Multi-Centre Prospective Randomised Control Trial to 
compare two articulating bearing surfaces, ceramic-on-metal 
and metal-on-metal using 38 mm M2a acetabular cup, as used 
in cementless primary hip arthroplasty 
Protocol Number 
BMETEU.CR.EU11 
Short Protocol Title 
COM vs MOM 
Sponsor 
Original: Biomet UK Ltd 
Administratively transferred: Biomet GSCC 
Administratively transferred: Zimmer GmbH, Zählerweg 4, 
6300 Zug, Switzerland 
Manufacturer 
M2a-38 acetabular cup: Biomet Orthopaedics Inc, USA 
M2a-38 38 mm cobalt chromium molybdenum (CoCrMo) 
modular heads: Biomet Orthopaedics Inc, USA 
Biolox delta 38 mm ceramic femoral head: CeramTec AG now 
CeramTec GmbH, Germany 
Bi-Metric femoral stem: Biomet UK Limited, Bridgend, UK 
Study Device(s) 
COM articulation: M2a38 acetabular cup with ceramic head 
articulation 
Comparator: MOM articulation: M2a38 acetabular cup with 
metal head articualtion 
Technical 
Documentation 
Reference Number 
NA 
Study 
Objectives/Endpoints 
To evaluate the clinical outcome of the ceramic-on-metal 
(COM) articulation using M2a38 cup with metal-on-metal 
(MOM) articulation using the same cup. 
 
The metal ion release and additional cellular markers will be 
evaluated at predetermined postoperative intervals during the 
first 36 months. 
 
Primary objective 
The aim of the study is to demonstrate the non-inferiority of the 
ceramic-on-metal articulation using M2a-38 cup compared to 
the metal-on-metal articulation using the same cup in regards to 
the CCS rate at 2 year postoperative (delta = 10 % minimum 
clinically significant difference in rates).  
Each patient’s CCS is defined as: 
 
• 
Total Harris Hip Score > 80 points, and 

 
 
COM vs. MOM 
Protocol number: BMETEU.CR.EU11 
Document date: 23-Sep-2008 
 
3 
• 
No acetabular or femoral revision or removal, and 
• 
No pending acetabular or femoral revision or removal 
as defined in radiographic evaluation by:  
▪ 
An acetabular radiographic assessment 
with all of the following: 
• 
Migration < 4 mm, and 
• 
Change in angle of inclination < 
4o, and  
• 
Absence of osteolysis, and  
▪ 
A femoral radiographic assessment 
with all of the following: 
• 
Subsidence < 5 mm, and 
• 
Absence of osteolysis. 
 
Secondary objective 
• 
Any reduction in metal ion release when using the 
ceramic-on-metal articulation compared to using 
metal-on-metal articulation. 
• 
Harris Hip Score at each post-operative visit. 
• 
Oxford Hip Score at each post-operative visit. 
• 
Womac Score at each post-operative visit.  
• 
Radiographic analysis at each post-operative visit.  
• 
Complications (including revisions/removals). 
• 
Long-term survivorship. 
Indications/Target 
Population 
Patients suitable for primary Total Hip Replacement. 
Inclusion/Exclusion 
Criteria 
Inclusion Criteria 
 
Patients suitable for primary Total Hip Replacement 
Patients with degenerative joint disease (inflammatory or non-
inflammatory) or any of the composite diagnoses of: 
a. 
Osteoarthritis 
b. 
Avascular necrosis 
c. 
Legg Perthes 
d. 
Rheumatoid Arthritis 
e. 
Diastrophic variant 
f. 
Fracture of the pelvis 
g. 
Fused hip 
h. 
Slipped capital epiphysis 
i. 
Subcapital fractures 
j. 
Traumatic arthritis 

 
 
COM vs. MOM 
Protocol number: BMETEU.CR.EU11 
Document date: 23-Sep-2008 
 
4 
Patients preoperative Harris Hip Score < 70 points 
Patients aged over 18 
Patients with limited co-morbidity – ASA I – III 
Patients with normal urea and electrolyte levels and creatinine 
levels 
Patients must be able to understand instructions and be willing 
to return for follow-up 
Patients willing to provide blood and urine samples for metal 
ion analysis at follow-up 
 
Exclusion Criteria 
Patients preoperative Harris Hip Score > 70 points 
Pre-existing metal implants 
Patients with significant co-morbidity - ASA IV - V 
Dementia and inability to understand and follow instructions 
Neurological conditions affecting movement   
Pregnancy  
Presence of symptomatic arthritis in other lower limb joints 
Study Design 
Prospective Randomised Controlled Trial 
Group 1: 
Ø 38 mm metal femoral head articulating against Metal M2a-38 
mm acetabular cup 
Group 2: 
Ø 38 mm ceramic femoral head articulating against Metal 
M2a-38 mm acetabular cup 
Clinical Phase 
Pre-market; COM articulation is not CE-marked 
Sample Size  
300 planned, 150 per arm.  
211 patients enrolled and included in study 
Length of Study 
12 years (2 year enrollment, with a follow-up of 10 years) 
Materials and 
Methods 
Case report forms will be completed either in-office or hospital 
at Pre-op, Surgery, Discharge, and the 6 week, 1-year, 2-year, 
and 5-year intervals. Case report forms will be completed at 
the 3-year, 7-year, and 10-year intervals either in-office, by 
phone or by mail. 
Data Collection 
Paper / electronic  
(Database: UK data in Access database; Finnish data in Joint 
Assist, study #339) 

 
 
COM vs. MOM 
Protocol number: BMETEU.CR.EU11 
Document date: 23-Sep-2008 
 
5 
Statistical Reporting 
Data collected will be summarized and reported to each 
participating investigator.  Statistical analysis will be conducted 
by Zimmer Biomet or its designee. Survivorship will be 
evaluated using Kaplan-Meier. 
Scores/Performance 
Assessments 
Harris Hip Score, Oxford Hip Score and WOMAC score 
Standards 
The PMCF is compliant with the below: 
• 
ISO 14155: 2020 - Clinical investigation of medical devices 
for human subjects - Good clinical practice.* 
• 
The Declaration of Helsinki (DoH) - Ethical principles for 
medical research involving human subjects.  
(*) The study protocol was drafted according to another version of the ISO 
14155. Adverse Event definitions and reporting are according to ISO 
14155:2020. 
Study Funding 
Funding for this clinical study is made available by Zimmer 
Biomet to support clinical data collection, IRB/EC review fees 
and other expenses associated with the conduct and execution 
of this study protocol as outlined in the fully executed Clinical 
Trial Agreement. 
 
1 
STATISTICAL ANALYSIS PLAN 
 
1.1 Sample Size 
The sample size is determined by the primary end-point of composite clinical success (CCS) 
at two years post-operative. Since the aim is to demonstrate the non-inferiority of the COM 
compared to the MOM group in terms of CCS, the sample size calculation is based on the 
Blackwelder method[15]. 
 
NULL hypothesis: 


−
1
2
p
p
 
 
ALTERNATIVE hypothesis: 


−
1
2
p
p
 
 
 = 0.10 
Difference in CCS rate between the MOM and COM groups that can 
be considered clinically significant 
 
Type I error ():  
The error of rejecting Null hypothesis when it is actually true (false 
positive) 
 

 
 
COM vs. MOM 
Protocol number: BMETEU.CR.EU11 
Document date: 23-Sep-2008 
 
6 
Type II error (): 
The error of failing to reject Null hypothesis when the alternative 
hypothesis is true (false negative) 
1.2  
 = 1.645 
 
When  = 0.05 
 
 = 1.28 
 
When  = 0.10, commonly used value in non-inferiority test 
 
p1 = 0.92 
 
Estimate CCS rate of COM group 
 
p2 = 0.92  
 
Estimate CCS rate of MOM group 
 
Sample size required, N: 
 


2
2
2
1
1
2
)
1(
)
1(
)
(



p
p
p
p
Z
Z
N
−
+
−
+
=
 
 
(
) 

126
10
.0
)
92
.0
1(
92
.0
)
92
.0
1(
92
.0
28
.1
645
.1
2
2
=
−
+
−
+
=
N
 
 
Consider 7.5 % lost to follow-up per year, there will be 15 % cases lost to follow-up at 2 years post-
operative.  
 
Final sample size: 
150
)
15
.0
1(
126
=
−
 
 
1.3 Statistical Analysis 
Statistical Analysis of the results will be conducted using a suitable method by a qualified 
statistician.