TITLE: Components and Materials used for Total Hip Replacement: A Review of the Comparative Clinical Effectiveness

Transcription

1 TITLE: Components and Materials used for Total Hip Replacement: A Review of the Comparative Clinical Effectiveness DATE: 22 October 2013 CONTEXT AND POLICY ISSUES Total hip arthroplasty (THA) involves the replacement of the femoral head, which fits into an acetabular cup that is secured into the pelvis. Almost 40% of joint replacements in the United States are hip replacements 1 and according to the Canadian Joint Replacement Registry, between 2009 and 2010, 13,068 Canadian patients received total hip arthroplasty. 2 This number has been increasing since Although hip replacements are successful in reducing pain and improving function, 3 many patients who undergo THA must undergo revision surgery within 10 years due to complications such as infection, dislocation, or loosening. 1 There are several designs available for hip implants, as well as different materials used for the implant components. Modular hip implants allow for the choice of different femoral neck lengths, femoral head sizes, as well as modular acetabular cups, 4 as opposed to standard implants. Materials used for the implant components must be biocompatible, as well as resistant enough to withstand the wear and tear associated with the use of the hip. 5 Various metals, plastics, and ceramics are used for hip implant components, each material having its own strengths and limitations. 5 Metal implant materials can allow for the use of larger femoral heads, 1 which may reduce the risk of dislocation, however, there is some evidence that this may result in corrosion 6 and the build-up of metal ions in tissues. 1 This can be especially important with respect to the head-neck taper interface of modular prostheses. 7 Ceramic components are not associated with the risk of metallic ion accumulation, but may be at higher risk for fracture than the metallic alternatives. 8 The objective of this report is to review the comparative clinical effectiveness and adverse events associated with THA using: a ceramic head on a ceramic acetabular liner or a ceramic head on cross-linked polyethylene acetabular liner versus a metal head on a cross-linked polyethylene acetabular liner; a modular primary stem versus a standard non-modular stem; or a metal femoral head of 36 mm and larger on a cross-linked polyethylene acetabular liner versus a metal femoral head of 28 to 32 mm on a cross-linked polyethylene acetabular liner. Disclaimer: The Rapid Response Service is an information service for those involved in planning and providing health care in Canada. Rapid responses are based on a limited literature search and are not comprehensive, systematic reviews. The intent is to provide a list of sources of the best evidence on the topic that CADTH could identify using all reasonable efforts within the time allowed. Rapid responses should be considered along with other types of information and health care considerations. The information included in this response is not intended to replace professional medical advice, nor should it be construed as a recommendation for or against the use of a particular health technology. Readers are also cautioned that a lack of good quality evidence does not necessarily mean a lack of effectiveness particularly in the case of new and emerging health technologies, for which little information can be found, but which may in future prove to be effective. While CADTH has taken care in the preparation of the report to ensure that its contents are accurate, complete and up to date, CADTH does not make any guarantee to that effect. CADTH is not liable for any loss or damages resulting from use of the information in the report. Copyright: This report contains CADTH copyright material and may contain material in which a third party owns copyright. This report may be used for the purposes of research or private study only. It may not be copied, posted on a web site, redistributed by or stored on an electronic system without the prior written permission of CADTH or applicable copyright owner. Links: This report may contain links to other information available on the websites of third parties on the Internet. CADTH does not have control over the content of such sites. Use of third party sites is governed by the owners own terms and conditions.

2 RESEARCH QUESTIONS Ceramic Implants 1. What is the clinical effectiveness of total hip replacement with a ceramic head on ceramic acetabular liner or ceramic head on cross-linked polyethylene acetabular liner versus a metal head on cross-linked polyethylene acetabular liner? 2. What is the clinical evidence regarding the adverse events and implant failures of total hip replacement with a ceramic head on ceramic acetabular liner or ceramic head on crosslinked polyethylene acetabular liner versus a metal head on cross-linked polyethylene liner? Modular Stem Implants 3. What is the clinical effectiveness of total hip replacement with a modular primary stem versus a standard non-modular stem? 4. What is the clinical evidence regarding the adverse events and implant failures of total hip replacement with a modular primary stem versus a standard non-modular stem? Large Femoral Head Implants 5. What is the clinical effectiveness of total hip replacement with a metal femoral head of 36 mm and larger on cross-linked polyethylene acetabular liner versus a metal femoral head of 28 to 32 mm on cross-linked polyethylene acetabular liner? 6. What is the clinical evidence regarding the adverse events and implant failures of total hip replacement with metal femoral head of 36 mm and larger on cross-linked polyethylene acetabular liner versus a metal femoral head of 28 to 32 mm on cross-linked polyethylene acetabular liner? KEY FINDINGS Based on evidence from a systematic review, there is no strong evidence indicating that ceramic on polyethylene implants are superior to metal on polyethylene implants, and some evidence that ceramic on ceramic implants require fewer revisions than metal on polyethylene hips after at least five years. Based on evidence from two non-randomized studies, modular stem implants may have lower early survival, but may be equal or superior to standard stems in the longer term and based on evidence from one randomized trial, large femoral head implants are likely beneficial over standard sized implants. More high quality comparative evidence, especially with respect to adverse events, is needed in order to draw strong conclusions. METHODS Literature Search Strategy A limited literature search was conducted on key resources including PubMed, The Cochrane Library (2013, Issue 8), University of York Centre for Reviews and Dissemination (CRD) databases, Canadian and major international health technology agencies, as well as a focused Total Hip Replacement 2

3 Internet search. No filters were applied to limit the retrieval by study type. Where possible, retrieval was limited to the human population. The search was also limited to English language documents published between January 1, 2008 and September 23, Rapid Response reports are organized so that the evidence for each research question is presented separately. Selection Criteria and Methods One reviewer screened citations and selected studies. In the first level of screening, titles and abstracts were reviewed for relevance. Full texts of any relevant titles or abstracts were retrieved, and assessed for inclusion. The final article selection was based on the inclusion criteria presented in Table 1. Population Intervention Comparator Outcomes Study Designs Table 1: Selection Criteria Adult patients undergoing total hip arthroplasty Q1,2: ceramic head on ceramic acetabular liner or ceramic head on cross-link acetabular liner Q 3,4: modular primary stem implants Q 5,6: metal femoral head implant 36 mm and larger Q1,2: metal head on cross-linked polyethylene acetabular liner Q 3,4: standard non-modular stem implant Q 5,6: metal femoral head implant 28 to 32 mm Clinical benefit (i.e. need for revision surgery) Harms (i.e. implant failure, adverse events) HTA, SR, MA, RCT, NRS HTA = health technology assessment; MA = meta-analysis; mm = millimeters; NRS = non-randomized study; RCT = randomized controlled trials; Q = question Exclusion Criteria Studies were excluded if they did not meet the selection criteria, if it was unclear as to whether acetabular liners were standard or cross-linked polyethylene, or if the report was published prior to Critical Appraisal of Individual Studies Critical appraisal of the included studies was based on study design. The methodological quality of the included systematic reviews and meta-analyses was evaluated using the assessment of multiple systematic reviews (AMSTAR). 9 AMSTAR is an 11-item checklist that has been developed to ensure reliability and construct validity of systematic reviews. The quality of randomized controlled trials (RCTs) and non-randomized studies (NRSs) were assessed using the Downs and Black checklist. 10 A numeric score was not calculated for each study. Instead, strengths and limitations of each study were summarized and described. Total Hip Replacement 3

4 SUMMARY OF EVIDENCE Quantity of Research Available A total of 386 potential citations were identified by searching the bibliographic database, with 363 citations being excluded during the title and abstract screening based on their irrelevance to the questions of interest. The full text documents of the remaining 23 articles were retrieved. One additional article was identified by grey literature and hand search. Of the 24 articles examined in full text, 20 did not meet the inclusion criteria and were excluded; leaving four articles that reported one systematic review (SR), one RCT, and two NRSs. A PRISMA diagram illustrating the study selection process is presented in Appendix 1. Additional references of potential interest that did not meet the selection criteria are provided in Appendix 5. Summary of Study Characteristics Ceramic Implants Study design One systematic review 1 pertaining to total hip replacement with a ceramic head on ceramic acetabular liner or ceramic head on cross-linked acetabular liner versus a metal head on crosslinked polyethylene acetabular liner was included in this review. Population The identified systematic review included clinical trials, observational studies, and registry data. 1 A total of 18 comparative studies examining 3,404 hips in 3,129 patients were included, four of which were relevant to the comparisons of interest in this review. The mean age of patients ranged between 42 and 71 and the percentage of female participants ranged from 26 to 88%. Intervention and Comparator Three studies included in the systematic review examined the comparative evidence of ceramicon-ceramic versus metal on cross-linked polyethylene implants and one study examined ceramic on cross-linked polyethylene versus metal on cross-linked polyethylene implants. 1 The specific brands of implants were not specified in the SR. Outcomes The primary outcomes reported in the systematic review were need for revision and hip dislocation. 1 Total Hip Replacement 4

5 Modular Stem Implants Study design Two non-randomized retrospective cohort studies 11,12 pertaining to total hip replacement with a modular primary stem versus a standard non-modular stem were included in this review. Population Both studies examined patients from hip registries. One of the studies examined 1,885 hips from the Swedish Hip Arthroplasty Register, 11 while the other examined 163 hips of patients with osteoarthritis and hip dysplasia from a Japanese registry. 12 Patients in the Swedish study had a mean age of 74 years and 48% were female. 11 Patients in the Japanese study had a mean age of 53.8 years and 90% were female. 12 Intervention and Comparison The modular stems used in both of the included studies were made of titanium alloy. 11,12 These were compared with patients receiving standard stems of various lengths and brands. The specific brands and measurements are included in Appendix 2 Table 4. Outcomes The primary outcomes examined were need for reoperation or revision, 11,12 prosthesis survival, 11 and complications. 12 Large Femoral Head Implants Study design One randomized controlled trial 13 compared total hip replacement with large femoral heads versus standard-sized femoral heads was included in this review. Population The RCT included 184 North American patients undergoing revision THA, 92 were randomized to a large sized femoral head and 92 to a standard head size. 13 The mean age of patients was 69 years and 74% of those included were women. Intervention and Comparator Patients were randomized to large femoral heads, that were either 36 mm or 40 mm, or standard-sized 32 mm femoral heads. 13 Further detail regarding the precise components is included in Appendix 2 Table 4;all components were Zimmer brand. Outcomes The primary outcomes examined in the study were dislocation and quality of life. 13 Total Hip Replacement 5

6 Additional detail regarding the study characteristics of all included studies is included in Appendix 2. Summary of Critical Appraisal Ceramic Implants Overall, the systematic review was of good quality. 1 Although an a priori design and lists of included and excluded studies were not included, duplicate study selection and extraction, a comprehensive literature search of three databases, and assessment of study quality were performed. Data was pooled where appropriate and publication bias was discussed. While a hand search of relevant references and searching patient record databases were a part of the search strategy, it was unclear if the grey literature was searched. This may have led to missing publications which are not indexed in the bibliographic databases, though it is unlikely that studies of key importance would have been missed. Modular Stem Implants The main strengths of the Swedish study 11 were that it had good reporting objectives, patient characteristics, outcomes, and confounders, and had good external and internal validity the patients were representative of the population, appropriate statistical tests were used, and the patients were recruited from the same population and timeframe. The primary limitations were lack of blinding (both patient and assessor) and a lack of information on patients lost to followup. The main strengths of the Japanese study 12 were the reporting of objectives, patient characteristics, main findings, patients lost to follow up and adverse events. The time period that both groups were recruited was the same, compliance to the interventions was good, and outcomes were appropriate with respect to the intervention and population. Although the patient sample was recruited from a representative population, the patients included in the study were primarily (90%) women and thus may not be truly representative of a therapeutic population. Further limitations include lack of blinding of both patients and assessors, lack of randomization, and it was unclear if there was adequate adjustment for confounding. Large Femoral Head Implants The randomized study examining large femoral head implants 13 was of overall good quality. It had good reporting of objectives, patient characteristics, interventions, main findings, and probability values. There was good external validity; subjects asked to participate in the study were likely representative of the population from which they were recruited, and the care they received was likely representative of the treatment the majority of patients receive, as both high and low volume centres were included in the study. Internal validity was also good; study subjects, caregivers, and all those related to the study, with the exception of the surgeon and operating room staff, were blinded, patients were recruited from the same population and over the same period of time and intervention assignment was concealed from the patients though the reporting of patients lost to follow-up was not clear. Further limitations included the lack of adverse event reporting. Further detail regarding the critical appraisal of all included studies is presented in Appendix 3. Total Hip Replacement 6

7 Summary of Findings Ceramic Implants The authors of the systematic review 1 did not conduct a meta-analysis of need for revisions or complications following THA. Instead, the results of the individual studies examined were presented. Three studies compared ceramic-on-ceramic implants with metal on cross-linked polyethylene implants. In the study with the shortest duration of follow-up (51 months), there were no significant differences between the need for revision or for dislocations following THA in the ceramic versus the metal groups. In the two studies with a longer duration (8 and 6.5 years) patients with metal on cross-linked polyethylene were statistically significantly more likely (P value not presented) to require revision surgery than those with ceramic-on-ceramic implants (10/165 vs. 6/349 and 10/165 vs. 1/186) and in the study reporting dislocation, there was no statistically significant difference between patients with metal on cross-linked polyethylene hips and those with ceramic-on-ceramic implants (7/165 patients vs. 10/349; P value not presented). One study examined ceramic on polyethylene versus metal on polyethylene implants. There were no differences between the need for revision between the two groups, and other complications were not reported. Modular Stem Implants Two non-randomized studies compared the use of modular stem implants with standard stem implants. In the study with the shorter duration of follow up 11 (3.4 years in the modular group, 4.2 years in the standard group) patients with the modular stem were more likely to require revision or reoperation than those with a standard stem (P value not presented), with dislocation being the most common reason for revision in the modular group. The hazard ratio for adjusted risk of reoperation in the modular versus standard stem was 1.7 (95% confidence interval [CI] = 1.3 to 2.4; P = 0.001) and for revision was 1.9 (95% CI = 1.2 to 3.1; P = 0.008). At three years, implant survival was better in the standard stem group, but beyond three years, survival was similar. In the study with a longer duration of follow-up 12 (14.5 years), although there were fewer patients in the modular stem group who required revisions (0/74 vs. 3/74) the difference was not statistically significant. There were no dislocations or ceramic head breakages in either group, and no fractures or notch formations in the modular hips. Osteolysis occurred in more patients in the standard stem group than in the modular stem group (59/74 vs. 20/74, P < ). Large Femoral Head Implants In the RCT that examined THA with a 36 mm or 40 mm femoral head versus a standard 28 mm femoral head, 13 patients who received the standard femoral head had more dislocations than those with the larger head (8/92 vs. 1/92, P = 0.035). Patients in both groups had improvements in quality of life. No adverse event data was reported. Further detail regarding the outcomes of all included studies is presented in Appendix 4. Total Hip Replacement 7

8 Limitations One of the limitations of this review is the limited number of studies identified for each research question. The comparative evidence regarding the different hip materials was limited and for this reason, non-comparative evidence and experimental studies using a simulator have been included in Appendix 5. Another potential limitation is that it was not always clear within the body of literature whether the polyethylene components were made of cross-linked polyethylene. The lack of randomization in many of the included studies is also a limitation. The two studies examining modular versus standard stem implants and one of the included studies in the systematic review comparing the implant material types were not randomized. It is possible that the differences found in these studies were due to factors other than the interventions being studied. With respect to the randomized trial that examined the size of the femoral head, if the reason for the surgery was revision of a previous hip implant, the majority of the patients underwent revision of both hips, thus the results may not be generalizable to patients undergoing single revision surgery. The short-term follow-up time is a further limitation of the included studies. Only two studies had follow-up longer than 6.5 years and one of these may not be generalizable to a larger context due to the fact that the patients in that study were 90% women and had osteoarthritis, secondary to hip dysplasia. As the newer hip materials continue to be used and examined, longer-term follow-up data may become available. CONCLUSIONS AND IMPLICATIONS FOR DECISION OR POLICY MAKING One systematic review, 1 one randomized controlled trial, 13 and two non-randomized studies 11,12 pertaining to ceramic implants, large femoral head implants, and modular stem implants respectively, were included in this review. Ceramic Implants The authors of the systematic review 1 concluded that there was limited evidence comparing the various hip surfaces and that there is no strong evidence indicating that ceramic-on-ceramic implants are superior to traditional hip surfaces. They suggested large, high quality randomized controlled trials in order to determine clinical benefit. No conclusions could be made regarding safety. Modular Stem Implants The authors of the NRS with the shortest follow-up 11 concluded that the modular stem had lower early (3-year) survival than the standard stem implant systems and recommended the use of a cemented long-stem prostheses in older patients and in patients with limited bone loss. The authors of the NRS with longer-term follow-up 12 (13 years) concluded that a stem system with a modular alumina ceramic head and liner may result in better outcomes for patients than a standard stem system, however this seems to be based primarily on the authors findings regarding osteolysis. Total Hip Replacement 8

9 Large Femoral Head Implants After a mean follow-up of five years, the authors of the randomized controlled trial 13 concluded that a large (36 mm or 40 mm) femoral head is more likely to prevent dislocation following THA than a standard sized head. Overall, more high quality comparative evidence, especially with respect to adverse events, is needed in order to draw strong conclusions regarding the comparative benefit of the hip implant systems examined in this review. Ceramic on ceramic implants seem to be associated with lower rates of revision than metal on cross-linked polyethylene implants. Large femoral head implants are likely beneficial over standard sized implants, however this conclusion is based on the results of one study examining 184 patients. PREPARED BY: Canadian Agency for Drugs and Technologies in Health Tel: Total Hip Replacement 9

10 REFERENCES 1. Sedrakyan A, Normand SL, Dabic S, Jacobs S, Graves S, Marinac-Dabic D. Comparative assessment of implantable hip devices with different bearing surfaces: systematic appraisal of evidence. BMJ [Internet] [cited 2013 Sep 26];343:d7434. Available from: 2. Canadian Institute for Health Information (CIHI) [Internet]. Hip and knee replacements in Canada annual statistics (clinical data). Ottawa: CIHI; 2012 [cited 2012 Oct 25]. Available from the website: cihi See under Reports and Analyses 3. Ho KW, Whitwell GS, Young SK. Reducing the rate of early primary hip dislocation by combining a change in surgical technique and an increase in femoral head diameter to 36 mm. Arch Orthop Trauma Surg Jul;132(7): Joint understanding. Health Devices [Internet]. Plymouth Meeting (PA): ECRI; 2012 [cited 2013 Oct 10]. Available from: (Subscription required). 5. Labek G, Sekyra K, Pawelka W, Janda W, Stockl B. Outcome and reproducibility of data concerning the Oxford unicompartmental knee arthroplasty: a structured literature review including arthroplasty registry data. Acta Orthop [Internet] Apr [cited 2013 Sep 26];82(2): Available from: 6. Cooper HJ, Urban RM, Wixson RL, Meneghini RM, Jacobs JJ. Adverse local tissue reaction arising from corrosion at the femoral neck-body junction in a dual-taper stem with a cobalt-chromium modular neck. J Bone Joint Surg Am May 15;95(10): Dyrkacz RM, Brandt JM, Ojo OA, Turgeon TR, Wyss UP. The influence of head size on corrosion and fretting behaviour at the head-neck interface of artificial hip joints. J Arthroplasty Jun;28(6): Koo KH, Ha YC, Jung WH, Kim SR, Yoo JJ, Kim HJ. Isolated fracture of the ceramic head after third-generation alumina-on-alumina total hip arthroplasty. J Bone Joint Surg Am Feb;90(2): Shea BJ, Grimshaw JM, Wells GA, Boers M, Andersson N, Hamel C, et al. Development of AMSTAR: a measurement tool to assess the methodological quality of systematic reviews. BMC Med Res Methodol [Internet] [cited 2013 Oct 13];7:10. Available from: Downs SH, Black N. The feasibility of creating a checklist for the assessment of the methodological quality both of randomised and non-randomised studies of health care interventions. J Epidemiol Community Health [Internet] Jun [cited 2013 Sep 6];52(6): Available from: Weiss RJ, Stark A, Kärrholm J. A modular cementless stem vs. cemented long-stem prostheses in revision surgery of the hip: a population-based study from the Swedish Hip Total Hip Replacement 10

11 Arthroplasty Register. Acta Orthop [Internet] Apr [cited 2013 Sep 26];82(2): Available from: Sakai T, Ohzono K, Nishii T, Miki H, Takao M, Sugano N. A modular femoral neck and head system works well in cementless total hip replacement for patients with developmental dysplasia of the hip. J Bone Joint Surg Br Jun;92(6): Garbuz DS, Masri BA, Duncan CP, Greidanus NV, Bohm ER, Petrak MJ, et al. The Frank Stinchfield Award: Dislocation in revision THA: do large heads (36 and 40 mm) result in reduced dislocation rates in a randomized clinical trial? Clin Orthop Relat Res [Internet] Feb [cited 2013 Sep 26];470(2): Available from: Total Hip Replacement 11

12 APPENDIX 1: Selection of Included Studies 386 citations identified from electronic literature search and screened 363 citations excluded 23 potentially relevant articles retrieved for scrutiny (full text, if available) 1 potentially relevant report retrieved from other sources (grey literature, hand search) 24 potentially relevant reports 20 reports excluded: -irrelevant population (2) -irrelevant intervention (4) -irrelevant comparator (9) -irrelevant outcomes (5) 4 reports included in review Total Hip Replacement 12

13 Appendix 2: Study Characteristics Table 2: Study Characteristics of the Included Study Examining Ceramic Implants Study Objectives; Type of Studies Included Patient Population Interventions Comparators Relevant Outcomes Sedrakyan, 2011, 1 Systematic Review To evaluate the safety and the effectiveness of different baring surfaces of hip implants. THA with ceramic on ceramic implants, ceramic on polyethylene implants THA with metal on polyethylene implants Revision after hip replacement, dislocation a Clinical trials, observational studies, registries. 3,139 patients; 3,404 hips in 18 included comparative studies examining various a hip implants. 3 studies examining ceramic-onceramic vs. metal on polyethylene (857 hips); 1 study examining ceramic on polyethylene vs. metal on polyethylene (114 hips). Mean age ranged between 42 and 71. Percentage of female participants ranged from 26 to 88. THA = total hip arthroplasty; vs. = versus a comparisons and outcomes that were not relevant to this review are not reported here. Registry data was presented, however it was unclear if the polyethylene was cross-linked. Table 3: Study Characteristics of the Studies Examining Modular vs. Long stem Implants Study Objectives Patient Population Interventions Comparators Outcomes Weiss, 2011, 11 Non-randomized Study Review the outcomes associated with the Link MP modular stem versus standard long-stem prostheses. 1,885 hips from the Swedish Hip Arthroplasty Register. 787 patients (812 hips) received MP stem, 1,053 patients (1,073 hips) received a standard stem. Mean age: 74 years 48% female Modular MP stem: titanium alloy with a microporous surface. Either 8 longitudinal flutes (stem size 12 to 16) or 10 longitudinal flutes (stem size 18 to 25) Included femoral components such as: Lubinus (length 170 to 350 mm); Spectron revision hip system (165 to 225 mm); Exeter long stem (200 to 300 mm) Reoperations, revisions, prosthesis survival Total Hip Replacement 13

14 Table 3: Study Characteristics of the Studies Examining Modular vs. Long stem Implants Study Objectives Patient Population Interventions Comparators Outcomes Sakai, 2010, 12 Non-randomized Study To compare modular stem versus conventional stem systems for total hip replacement for patients with hip dysplasia. mm = millimeter 133 patients (163 hips) with osteoarthritis, secondary to hip dysplasia 67 patients (83 hips) received modular system; 66 patients (80 hips) nonmodular system Mean age: % female Custom designed femoral component, modular neck system, (made from titanium alloy) cementless acetabular component: conventional polyethylene liner, 28 mm alumina head Anatomical metal cancellous femoral component, (made from cobalt chrome molybdenum alloy), cementless acetabular component: conventional polyethylene liner, 28 mm alumina head Need for revision, complications Table 4: Study Characteristics of the Study Examining Large Femoral Head Implants Study Objectives Patient Population Interventions Comparators Outcomes Garbuz, Randomized Controlled Trial To determine if a 36 or 40 mm femoral head resulted in fewer dislocations than a standard 32 mm femoral head. 184 North American patients undergoing revision THA between 2003 and randomized to a large sized femoral head, 92 randomized to standard head. Mean age: 69 years 74% women Mean BMI: 27.4 Large sized femoral head (36 mm or 40 mm). VerSys1 beaded fullcoated (Zimmer) or ZMR (Zimmer) femoral stem or CPT (Zimmer) cemented stem, VerSys1 36- or 40-mm cobaltchrome head (Zimmer). Acetabular liner: Trilogy1 cup (Zimmer) or the Trabecular Metal modular shell (Zimmer). Standard femoral head (32 mm) VerSys1 beaded fullcoated (Zimmer) or ZMR (Zimmer) femoral stem or CPT (Zimmer) cemented stem, VerSys1 cobalt-chrome head (Zimmer). Acetabular liner: Trilogy1 cup (Zimmer) or the Trabecular Metal modular shell (Zimmer). Dislocation, Quality of Life Longevity highly crosslinked acetabular liner (Zimmer) was used in Longevity highly crosslinked acetabular liner (Zimmer) was used in Total Hip Replacement 14

15 Table 4: Study Characteristics of the Study Examining Large Femoral Head Implants Study Objectives Patient Population Interventions Comparators Outcomes both shells. both shells. Majority of procedures (62 of 92) were posterolateral BMI = body mass index; mm = millimeter; THA = total hip arthroplasty Majority of procedures (68 of 92) were posterolateral Total Hip Replacement 15

16 Appendix 3: Critical Appraisal Table 5: Critical Appraisal of the Included Systematic Review 1 Strengths Limitations Duplicate study selection and data extraction A priori' design not provided Comprehensive literature search performed - multiple databases, hand search, - search terms and more details provided in web appendix. Unclear if grey literature searched. List of included and excluded studies not provided. Status of publication was used as an inclusion criterion. Characteristics of the included studies provided; however it was sometimes unclear as to which studies were included in each analysis in the text. Scientific quality of the included studies assessed and documented (using STROBE). Scientific quality of the included studies used appropriately in formulating conclusions. Methods used to combine the findings of studies appropriate. Likelihood of publication bias was discussed. Conflict of interest statement included. Table 6: Critical Appraisal of the Included Randomized and Non-Randomized Studies Strengths Limitations Garbuz, Randomized Controlled Trial REPORTING REPORTING The objectives of the study are clearly described. Not all important adverse events that may be a The main outcomes to be measured clearly consequence of the intervention were reported. described in the Methods section. No mention of patients lost to follow-up or how Characteristics of the patients included in the study many patients completed the study. clearly described. Interventions of interest clearly described. INTERNAL VALIDITY (confounding/selection bias) Study was randomized and an even distribution of Reporting of patient losses was not clear. possible confounders was present. The main findings of the study were clearly Described. Estimates of the random variability in the data for the main outcomes were presented. Actual probability values reported (e.g rather than <0.05) for the main outcomes except where the probability value is less than EXTERNAL VALIDITY The subjects asked to participate in the study were likely representative of the entire population from which they were recruited. Total Hip Replacement 16

17 Table 6: Critical Appraisal of the Included Randomized and Non-Randomized Studies Strengths Limitations The staff, places, and facilities where the patients were treated, were representative of the treatment the majority of patients receive both high and low volume centres were included in the study INTERNAL VALIDITY (bias) Study subjects, caregivers, and all those related to the study, with the exception of the surgeon and operating room staff, were blinded. Does not appear that data dredging occurred. The statistical tests used to assess the main outcomes were appropriate. Compliance with the intervention was reliable. The main outcome measures used were accurate, valid, and reliable INTERNAL VALIDITY (confounding/selection bias) The patients in different intervention groups were recruited from the same population and over the same period of time. Study subjects randomized to intervention groups, and intervention assignment was concealed from the patients, and staff until recruitment was complete. If the patient was assigned a large femoral head and during surgery it became clear that the size was too big, the smaller head could be used. POWER Power calculation was presented. This was a superiority trial, α was set at 0.05 and power was 80%. Weiss, 2011, 11 Non-randomized Study REPORTING The objective of the study is clearly described The main outcomes to be measured clearly described in the methods section/ The characteristics of the patients included in the study and the interventions of interest are clearly described. The distributions of principal confounders in each group of subjects to be compared are partially described. The main findings of the study are clearly described. Estimates of the random variability in the data provided for the main outcomes Actual probability values been reported (e.g rather than <0.05) for the main outcomes. Some but not all important adverse events reported. REPORTING Reporting of patients lost to follow-up is unclear. INTERNAL VALIDITY (bias) Patients were not blinded registry data was used. Those measuring the main outcomes of the intervention were not blinded INTERNAL VALIDITY (confounding/selection bias) Subjects were not randomized to intervention groups. Limited information on patients lost to follow-up, however registry data was used and this may not be an important factor. Total Hip Replacement 17

18 Table 6: Critical Appraisal of the Included Randomized and Non-Randomized Studies Strengths Limitations EXTERNAL VALIDITY Subjects in the study were likely representative of those in the entire population. The staff, places, and facilities where the patients were treated, likely representative of the treatment the majority of patients receive. INTERNAL VALIDITY (bias) Results do not appear to be based on data dredging. Hazard Ratios and survival were adjusted for the different time periods of follow up. Statistical tests used to assess the main outcomes were appropriate. Compliance with the intervention was reliable The main outcome measures used were accurate (valid and reliable). INTERNAL VALIDITY (confounding/selection bias) Patients in different intervention groups were from the same population registry data was used. The study subjects in different intervention groups were recruited from the same period of time 1999 to Cox multiple regression model used to adjust for confounding in the analyses from which the main findings were drawn. POWER Study had sufficient power to detect a clinically important effect where the probability value for a difference being due to chance is less than 5%. Sakai, 2010, 12 Non-randomized Study REPORTING The objective of the study was clearly described. The main outcomes to be measured were clearly described in the methods section. The characteristics of the patients included in the study were clearly described. The interventions of interest were clearly described. The distributions of principal confounders in each group of subjects to be compared were clearly described. The main findings of the study were clearly described. Study provides estimates of the random variability in the data for the main outcomes. Important adverse events reported. No patients lost to follow-up. EXTERNAL VALIDITY Subjects asked to participate in the study likely representative of the entire population from which REPORTING Actual probability values not reported. EXTERNAL VALIDITY Subjects who participated were not likely representative of the entire population from which they were recruited a much higher percentage of women participated in the study than did men. Single centre represented, so staff, places, and facilities where the patients were treated may not be fully representative of the treatment the majority of patients receive, especially with respect to difference in patient volume and expertise. INTERNAL VALIDITY (bias) Patients were not blinded. Those measuring the main outcomes of the intervention were not blinded. INTERNAL VALIDITY (confounding/selection bias) Total Hip Replacement 18

19 Table 6: Critical Appraisal of the Included Randomized and Non-Randomized Studies Strengths Limitations they were recruited. Subjects were not randomized to intervention groups. INTERNAL VALIDITY (bias) Unclear if there was adequate adjustment for Results of the study based on data dredging, not confounding in the analyses from which the main likely findings were drawn. The time period between the intervention and outcome was the same for cases and controls. The statistical tests used to assess the main outcomes were appropriate. The compliance with the intervention was reliable. The main outcome measures used were accurate. INTERNAL VALIDITY (confounding/selection bias) The patients in different intervention groups (were recruited from the same population and same time period. (Retrospective data) Did not appear to be any patients lost to follow up. POWER No power calculation presented but likely sufficient power to detect a clinically important effect where the probability value for a difference being due to chance is less than 5%. Total Hip Replacement 19

20 Appendix 4: Study Outcomes Ceramic Implants Table 7: Summary of Study Outcomes for the Study Examining Ceramic Implants 1 Comparison Studies Revision Surgery Needed Dislocation Ceramic-on-ceramic vs. Bascarevic, 2010 (51 Ceramic: 2/82 Ceramic: 1/82 metal on polyethylene months follow-up) Metal: 2/75 Metal: 2/75 Capello, 2008; D Antonio, Ceramic: 6/349 Ceramic: 10/ (8 years follow-up) Metal: 10/165 a Metal: 7/165 Capello 2008, addition of Trident system (6.5 years follow up) (statistically significant) Ceramic: 1/186 Metal: 10/165 a (statistically significant) Ceramic on polyethylene vs. metal on polyethylene. von Schewelov, 2005 (5 years follow up) Ceramic: 1/58 Metal: 3/56 vs. = versus a metal on polyethylene group likely the same patients in both studies NR NR Authors Conclusions Substantially lower occurrence of revision in the ceramic on ceramic arms compared with metal on polyethylene arm. However overall conclusion that there were no advantages to ceramic on ceramic versus traditional bearings. No differences in need for revision surgery Modular Stem Implants Table 8: Summary of Study Outcomes for the Studies Examining Modular versus Standard Stem Implant Systems Comparison Reoperations or Revisions Survival Complications and Adverse Events Author Conclusions Weiss, 2011, 11 Non-randomized Study Modular MP stem Not reported. vs standard stem Mean follow up Modular: 3.4 years Standard: 4.2 years MP Stem: 93/812 (11%) hips required reoperation 39/812 (5%) hips required overall revision Most common reasons for MP revision: dislocation: 17 aseptic loosening: 6 deep infection: 5 MP Stem vs. Standard Stem: Adjusted risk of reoperation: HR = 1.7; 95% CI = 1.3 to 2.4; P = Adjusted risk of revision: HR = 1.9; 95% CI = 1.2 to 3.1; P = The MP stem had lower early survival than the standard long cemented stem. They recommended the use of a cemented longstem prostheses in older patients and in patients with limited bone loss. Total Hip Replacement 20

21 Table 8: Summary of Study Outcomes for the Studies Examining Modular versus Standard Stem Implant Systems Comparison Reoperations or Revisions Survival Complications and Author Conclusions Adverse Events Surgery types: Proximal part exchanged or adjusted: 23 Entire stem exchanged or extracted: 16 Cup or liner exchanged or extracted: 18 Femoral head exchanged: 8 After 3 years follow-up, survival (reoperation and revision) was better in the standard long-stem group, but beyond 3 years, there was no difference in survival between the groups. Standard Stem: 32/1073 hips required revision Reasons for revision: dislocation: 2 aseptic loosening: 19 deep infection: 4 periprosthetic fracture: 7 Risk factors for reoperation: Decreasing age at primary hip arthroplasty: HR = 1.1 (95% CI 1.0 to 1.1) P = 0.02 Multiple previous revisions: HR = 2.6 (95% CI 1.1 to 6.2) P = 0.04 Short stem length: HR = 2.5 (95% CI 1.1 to 5.2) P = 0.03 Standard neck offset: HR = 5 (95% CI 1.5 to 17) P = Short head-neck length: HR = 5.3 (95% CI 1.4 to 21) Risk for several or all parts revision: Decreasing age: HR = 1.1 (95% CI 1 to 1.2) P = 0.03 Multiple previous revisions: HR = 3.8 CI 1 to 14.7) P = 0.05 Total Hip Replacement 21

22 Table 8: Summary of Study Outcomes for the Studies Examining Modular versus Standard Stem Implant Systems Comparison Reoperations or Revisions Survival Complications and Author Conclusions Adverse Events Short stem length: HR = 4.1 (95% CI 1.4 to 12) P = 0.01 Sakai, 2010, 12 Non-randomized Study modular stem versus conventional stem systems Revisions Modular hip: 0/74 Standard: 3/74 (2 due to acetabular component, 1 due to stem) Not reported Osteolysis Modular hip: 20/74 Standard: 59/74 P < P = n.s. Mean follow-up: 14.5 years Loosening: Modular hip: 6/74 (4 acetabular, 2 stem) Standard: 5/74 (4 acetabular, 1 stem) P = n.s. CI = confidence interval; HR = hazard ratio; n.s = non-significant; No infections, dislocations, or ceramic head breakages in either group No dislocations, fractures, or notch formations in the modular hips. The modular system with a modular alumina ceramic head and liner may result in better outcomes for patients after 13 years follow-up. The system also reduces the need for an elevated liner. Large Femoral Head Implants Table 9: Summary of Study Outcomes for the Study Examining Large Femoral Head Implants 13 Comparison Dislocation Quality of Life Other Author Conclusions THA with 36 mm or 40 mm femoral head vs. THA with standard 28 mm femoral head Large Head: 1/92 (1.1%) Standard: 8/92 (8.7%) Difference statistically significant (P = 0.035) 1 patient in the large head group, 3 patients in standard head group required surgery following dislocation Mean time to dislocation: 131 days mm = millimeter; QoL = quality of life; THA = total hip arthroplasty All patients had improvements in quality of life. SF-36 mental component was the only QoL score that differed between groups. Large head scored higher than standard head (P = 0.043) Mean follow-up for dislocation: 5 years QoL outcomes were measured after a mean of 2 years Large femoral heads are more likely to prevent dislocation than standard sized heads after THA. Total Hip Replacement 22

23 Appendix 5: Additional References Non-Comparative Studies 1. Choy WS, Kim KJ, Lee SK, Bae KW, Hwang YS, Park CK. Ceramic-on-ceramic total hip arthroplasty: minimum of six-year follow-up study. Clin Orthop Surg Sep;5(3): Available from: 2. Brandt JM, Gascoyne TC, Guenther LE, Allen A, Hedden DR, Turgeon TR, et al. Clinical failure analysis of contemporary ceramic-on-ceramic total hip replacements. Proc Inst Mech Eng H Aug;227(8): Restrepo C, Mashadi M, Parvizi J, Austin MS, Hozack WJ. Modular femoral stems for revision total hip arthroplasty. Clin Orthop Relat Res Feb;469(2): Available from: 4. Traina F, De FM, Tassinari E, Sudanese A, Calderoni PP, Toni A. Modular neck prostheses in DDH patients: 11-year results. J Orthop Sci Jan;16(1): Fink B, Grossmann A, Schubring S, Schulz MS, Fuerst M. Short-term results of hip revisions with a curved cementless modular stem in association with the surgical approach. Arch Orthop Trauma Surg Jan;129(1): Rodriguez JA, Fada R, Murphy SB, Rasquinha VJ, Ranawat CS. Two-year to five-year follow-up of femoral defects in femoral revision treated with the link MP modular stem. J Arthroplasty Aug;24(5): Garcia-Rey E, Munoz T, Montejo J, Martinez J. Results of a hydroxyapatite-coated modular femoral stem in primary total hip arthroplasty. A minimum 5-year follow-up. J Arthroplasty Dec;23(8): Mai K, Hardwick ME, Walker RH, Copp SN, Ezzet KA, Colwell CW, Jr. Early dislocation rate in ceramic-on-ceramic total hip arthroplasty. HSS J Feb;4(1):10-3. Available from: Simulator Studies 9. Zietz C, Fabry C, Middelborg L, Fulda G, Mittelmeier W, Bader R. Wear testing and particle characterisation of sequentially crosslinked polyethylene acetabular liners using different femoral head sizes. J Mater Sci Mater Med Aug;24(8): Total Hip Replacement 23

24 10. Bougherara H, Zdero R, Shah S, Miric M, Papini M, Zalzal P, et al. A biomechanical assessment of modular and monoblock revision hip implants using FE analysis and strain gage measurements. J Orthop Surg Res. 2010;5:34. Available from: Kelly NH, Rajadhyaksha AD, Wright TM, Maher SA, Westrich GH. High stress conditions do not increase wear of thin highly crosslinked UHMWPE. Clin Orthop Relat Res Feb;468(2): Available from: Total Hip Replacement 24