Outcomes of Birmingham Hip Resurfacing: a systematic review.
Hip pathology is a common diagnosis that can cause pain and limit activity. In a younger population hip pain commonly occurs from pathology to the labrum. Progressive degeneration in these patients may eventually lead to osteoarthritis (OA)[2,3]. It is estimated that 0.4% to 27% of adults have some form of hip osteoarthritis . The traditional surgical treatment for those with OA who have failed conservative treatment is total hip arthroplasty (THA). However, THA has been reported to fail in younger patients with more active lifestyles [5-7]. Recently, hip resurfacing (HR) has emerged as a relatively new surgery that has potential advantage to eliminate these failure issues encountered with THA in select individuals. There are a variety of devices that are options for HR and they include; Durom Hybrid System by Zimmer, Conserve Plus by Wright, Cormet MoM by Corin, and the Birmingham HR (BHR, Smith & Nephew Inc., Memphis, TN, USA) system by Smith and Nephew.
Specifically, Birmingham Hip Resurfacing is said to "allow you to return to most activities, including impact activities," according to the Smith and Nephew website. This direct to patient advertising has had an effect on patient education. In a study considering a group of patients presenting to one clinic for consultation for hip pain, 41% were aware of HR . Of these patients 46% learned of the procedure from the internet, 42% through family or friends, and only 19% from an orthopedic surgeon. A majority of these patients preferred to have HR and 82% felt that it was safer than THA.
Despite its technical challenge BHR has grown in popularity around the world . This new procedure was approved by the FDA in 2006, and is now in use in the United States . The primary aim of BHR may not be return to a higher level of function; it simply may be to decrease pain from hip osteoarthritis for a period of time before a revision is needed. BHR may decrease this pain to the equivalent level of a THA, while still preserving the femur. However, more active patients considering this surgical option will need to be educated on its long-term outcomes and their potential to return to sporting activities. The purpose of this paper is to provide a systematic review of the current literature available for the functional outcomes of BHR.
METHODS AND SUBJECTS
We performed a computerized search of publications listed in the electronic data bases CINAHL Plus with Full Text, Medline (Ovid), and SPORT Discuss up to February 2011. The following text and key words were searched: "Birmingham hip", "Birmingham hip resurfacing" and "Hip resurfacing". Each of these key words was again searched with "outcomes" following them. We also searched the bibliographies of the retrieved articles and our own files to identify specifically relevant articles.
Studies were included for review if: 1) patients received Birmingham Hip resurfacing, 2) an outcome measure of any type was completed and 3) a portion of the group whose outcome was assessed had received Birmingham Hip resurfacing.
Data Extraction and quality assessment:
The investigator independently extracted data using a standardized form. Data were extracted for study design, patient inclusion, patient exclusion, outcomes assessed, duration of follow up and results. Not every study had all of this data. No attempt was made to ascertain quality of the research since the intent of the paper was to report on specific outcomes of a specific surgery. The brevity of the literature required us to consider most of the research we identified.
Study Identification and selection:
Using the predefined search strategy, 315 titles were returned. Many of these titles were repeated in each search. Of these, 18 titles were identified as eligible for the review.
Detailed characteristics of the author and year of publication, Sackett level of evidence , and quality score based on AACPDM (www.aacpdm.org), study design, patient inclusion, patient exclusion, intervention, outcomes assessed, and duration of follow up and results are available in Table 1.
Three prospective studies were identified. Two had outcomes pre and post-operatively and one issued a post-operative employment survey. Fifteen retrospective studies were identified. Six with post operative outcomes, three with post operative surveys, five with pre and post-op outcomes, and one with a pre and post-op questionnaire. No randomized control trials were identified. No studies with control groups were identified. The maximum follow up for any research was 10 years using a survey or outcome tools.
Eleven of the papers identified did not provide descriptions of the operative method, other than to identify it as a BHR. Four identified the BHR approach as posterior [12-16] one as extended posterior  and one as modified extended posterior . No research was identified that examined a specific operative method of BHR and its effects on postoperative outcomes.
Four of the articles discussed post-operative rehabilitation. One study stated that the post-operative protocols varied . Another study stated that the early rehabilitation was "slow", but eventually was "normal" . Two studies included specific post-operative criteria. One encouraged immediate full weight bearing, but allowed the use of one or two canes. Another implemented traditional THA precautions for six weeks, dictated partial weight bearing for the first week, followed by the use of a cane(s) for one to two weeks as needed . No research was identified that evaluated a specific postoperative rehabilitative course.
Duration of follow-up:
The duration of follow-up varied significantly among the research from six months to ten years. Seven studies had group results for less than five years [12,15,17,19-22, two for exactly five years [13,23] and eight for longer than five years [14,16,17,24-28].
Of the seven studies that included pre and postoperative outcomes three documented increases in hip flexion active range of motion (AROM), one by a mean of 18.9 degrees, one noted a significant improvement, and another showed a mean hip flexion of 120.36 degrees [12,29,15]. Six assessed the Harris Hip Score (HHS) and noted the following: an increase of 56, means of 96.4 and 84.8, poorer outcomes with lesser Charnley grades, one simply noted improvement, and two noted significant improvement [12,21,23-25,28,29]. The four studies which noted the Oxford Hip Score (OHS) found means of 16.1 and 16.4, a mean 26.3 improvement, a mean of 21.4, and poorer outcomes with lower Charnley grades [12,24,25]. One study reported the median modified OHS as 4.2% using the Pynsent method . The five that documented the University of California Los Angeles Activity Score (UCLA AS) noted means of 6.6 and 6.7, a 3.61 improvement, a mean of 8.4, statistical improvement, and a median of 7.0 [14,16-18,24].
One study included a pre and post-operative questionnaire and had participants' complete information on sports participation before and after BHR. 65% were active in sports preoperatively, and this increased to 92% postoperatively. 92% reported that their sporting function had improved. There was a significant difference in the intensity and frequency of sports participation .
Of the six studies which detailed only post-operative outcomes, those that used the HHS reported means of 95.3, 97.24 and 84.8 [15,25,26]. One author reported that the HHS had him conclude that BHR was effective for a younger, active population. The scores were not reported . On those that used the UCLA AS provided means of 8.4  and 6.7  Studies reporting the OHS listed means of 15.9  and 16.4  One study reported satisfaction means of 2.53 out of a 0 (poor) to 3 (excellent) scale . Finally, where AROM hip flexion was considered, the mean was 100 degrees .
The three studies which contained only post operative questionnaires included reports of adverse events, sports participation, and employment status [19,20,27]. Adverse events were less than one percent. Sports participation was reported to have declined in high and intermediate impact activities and increased in low impact activities. One third of the subjects reported they had to give up sports that they intended on continuing. Employment surveys showed 90% of patients' employment was not affected.
The research identified using outcomes to report on BHR falls into the Level of Evidence: 4 of the Sackett scale. Level 4 is defined as a "Case series and poor quality cohort and case-control studies" . This limitation in research design does not allow for a complete appreciation of the outcomes of BHR, either on its own or in comparison with THA, arthroscopic procedures, other hip resurfacing systems, or absence of surgical intervention.
The quality assessment scale as defined by AACPDM in the included research had a mean of 3.25 on the 7 point scale. Only three of the studies presented clear inclusion and exclusion criteria. Six of the studies clearly noted the surgical approach utilized, while four contained comments concerning the post-operative care and/or rehabilitation. While some of the outcome tools used, such as the HHS, OHS, and UCLA AS have been shown to be valid, their reliability when applied to BHR has not yet been established. None of the studies utilized any type of blinding when assessing the patients. Use of statistical evaluation and power analysis varied in the research. Finally, the dropout/loss rate was typically below the established 20% and reported failure rates were acceptable.
BHR is currently being used worldwide as a means to delay THA in the younger patient with OA of the hip or as an option for the more active individual. BHR is chosen in active individuals because a higher level of activity post THA is typically not advised and can be damaging to the implant. In addition, the patient's own femur is spared due to the surgical method.
While the sparing of the femur does occur, whether a patient can maintain a high level of function post BHR is not known. The current literature on BHR, a specific type of hip resurfacing, is lacking and has not shown the results that the theoretical concepts suggest or the manufacturer of the device has advocated. Our review of the literature suggests that more complete research is needed. We would suggest utilization of outcome tools such as the Western Ontario and McMaster Universities' Osteoarthritis Index (WOMAC) and the HHS. These outcome tools have been validated . These measures should be assessed pre-operatively and post-operatively as part of the evaluation and follow up process. In addition they could be used for comparisons of various surgical approaches and post-operative rehabilitation protocols. Clearer inclusion and exclusion criteria as well as longer follow-up would also add to the body of research. Once these questions have been addressed, we may better educate our patients who are considering this relatively new procedure.
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Steve Karas, DSc, PT, CMPT, OCS
Chatham University, Pittsburgh, PA, USA
* Corresponding Author;
Address: Physical Therapy Department, Chatham University, USA
Received: Aug 01, 2011
Accepted: Oct 03, 2011
Author, year Study Design Patient Inclusion Sackett Level, Quality score Back, 2005 Prospective, n=230, BHR patients in one 4 mean age=52.1 center operated on by 4/7 three surgeons. Pain, limp, limitation of ADL's. males < 75 yo, females < 60yo Kim, 2007 Retrospective, n=20, BHR patients in one 4 mean age=35.9 (22-65) center NA Valle, 2009. Retrospective, n=537, BHR patents of 89 4 mean age=52 (16-E2) surgeons in the US with 2/7 varying experience levels Steffen, 2007 Retrospective, BHR patients at one 4 independent series. center. 3/7 n=610 mean age=51.8 in entire group. n=110, mean age=50.5 in 5 year follow up group. Treacy, 2005 Retrospective, Patients with BHR 4 n=130, mean age=52.1 performed by single 3/7 surgeon bused on age, subjective quality of and patient's expectations of postoperative activity level. Heilpern, Retrospective. BHR performed by a 2008. n=117, mean age=54.5 single surgeon. 4 3/7 Madhu, 2009. Retrospective Cohort, BHR performed by a 4 n=117, mean age=54 (0- single surgeon. 4/7 74) Reito, 2010. Retrospective cohort, BHR performed at a 4 n=144 single center. 3/7 Narvani, 2006. Retrospective Cohort, BHR patients. 4 N=51 3/7 Pollard, 2006. Retrospective, BHR performed by a 4 n=63 for BHR, single surgeon. 5/7 Banerjee, Retrospective case BHR performed at a 2010 series. n=159, Mean single center. Men > 60 4/7 ages: <55:n=88.>55: yo, women > 55 yo, a n=64 preoperative high activity level via subjective report. Malek, 2010 n=100, prospective BHR performed by a 4 cohort, mean age=51 single surgeon. 1/7 Rose, 2010 N=96, retrospective BHR performed in a 4 cohort single center on 5/7 patients with a diagnosis of femoral head avascular necrosis. Smet, 2002 n=200, retrospective. BHR performed in 4 mean age=49.5 (16-75) single center 5/7 Khan, 2009 n=652, prospective BHR mulicenter study 4 multicenter study, performed by 58 3/7 median age=51 surgeons in 8 countries. (15.8-87.9) Larbpaiboon- n=40, restrospective BHR of single surgeon. pong, 2009 single center 4 3/7 Treacy, 2011 N=144 BHR of a single 4 surgeon that were 4/7 included in same surgeon's live year follow up Hing, 2007 N=230, retrospective BHR 4 3/7 Authur, year Patient Inclusion Intervention Sackett Level, Quality score Back, 2005 Osteopenia or BHR posterior 4 osteoporosis, renal approach. 4/7 impairment, metal sensitivity, long term Post operative steroid use, previous rehabilitation varied pelvie and femoral between surgeons surgery, poor bone stock. Leg length discrepancy >3cm Kim,2007 NA BHR 4 NA Valle, 2009. NA BHR 4 2/7 Steffen, 2007 NA BHR extended 4 posterior approach 3/7 Treacy, 2005 NA BHR posterior 4 approach. 3/7 Initially full weight bearing, but encouraged to use two, then one cane. Heilpern, NA BHR 2008. 4 3/7 Madhu, 2009. NA BHR 4 4/7 Reito, 2010. NA BHR 4 3/7 Narvani, 2006. NA BHR 4 3/7 Pollard, 2006. Operative decision to BHR posterior 4 exclude. approach. 5/7 Banerjee, Known osteoporosis. BHR. 2010 femoral head cyst PWB for one week. 4/7 >1cm, varus deformity Cane(s) far two weeks. at the femoral head Initial 6 weeks post op: no flexion >90, no internal rotation. adduction or active external rotation Malek, 2010 NA BHR 4 1/7 Rose, 2010 Patients with bilateral BHR: modification of 4 AVN prior to 4 year the extended posterior 5/7 follow up approach Smet, 2002 NA BHR posterior 4 approach. 5/7 "...the early post operative rehabilitation sometimes progresses only slowly, but with time it becomes almost normal" Khan, 2009 NA BHR 4 3/7 Larbpaiboon- Patient with secondary BHR pong, 2009 osteonecrosis 4 3/7 Treacy, 2011 NA BHR posterior 4 approach. 4/7 Initially full weight bearing, but encouraged to use two, then one cane. Hing, 2007 NA BHR 4 3/7 Authur, year Outcomes assessed Duration of follow-up Sackett Level, Quality score Back, 2005 Pre-op: HHS, short Mean follow- up=3 4 form-12, Charnley years (2,0-4.4) 4/7 grades Post-op: HHS, short form-12, Charnley grades, OHS, flexion ROM Kim,2007 Pre-op: HHS Mean follow-up=5 4 years NA Post-op: HHS Valle, 2009. Pre-op: none Mean follow- 4 up=10.4 months 2/7 Post-op: Physician completed "Adverse Even! Report" Steffen, 2007 Pre-op: none Entire group: mean 4 follow- up=4,2 3/7 Post-op: years. OHS and UCLA AS Five year group mean follow-up: 5,3 years. Treacy, 2005 Pre-op: none 5 year 4 3/7 Post-op: HHS Heilpern, Pre-op: HHS, OHS, Mean follow-up- 6 2008. UCLA AS years, Minimum 4 Post-op:HHS, OHS, follow-up of 5 years 3/7 UCLA AS Madhu, 2009. Pie-op: none Mean follow up 7 4 years, minimum of 5 4/7 Post-op:OHS, HHS, years flexion ROM Reito, 2010. Pre-op: none Follow-up=5 to 8 4 Post-op: HHS, patient years 3/7 satisfaction (0-1 scale where 0=poor, 3=excellent) Narvani, 2006. Pre-op: Sports Activity Minimum of 6 4 Questionnaire months 3/7 Post-op: Sports Activity Questionnaire Pollard, 2006. Pre-op: none Mean follow up 61 4 months (52-71) 5/7 Post-op: OHS, UCLA AS Banerjee, Post-op: Questionnaire Mean follow-up of 2 2010 regarding their activity years post op 4/7 level before and after surgery. Sports were assigned ranks of 1 for low impact, 2 for intermediate impact, and 3 for high impact Malek, 2010 Employment surveys 10 year follow up 4 1/7 Rose, 2010 Pre-op: UCLA AS Mean follow up=5.4 4 years (4-8.1) 5/7 Post-op: UCLA AS Smet, 2002 Pre-op: none Follow-up range: 6 4 months to 3,5 years 5/7 Post-op: HHS, Hip flexion ROM, pain Khan, 2009 Pre-op: HHS, score Follow-up: 4 Post-op: HHS, median=6 years (5-8 3/7 general satisfaction years) questionnaire. D'Aubigne score Larbpaiboon- Pre-op: HHS, OHS. Follow-up pong, 2009 UCLA AS, Short form mean=16,2 4 12 score months(3-33) 3/7 Post-op: HHS, OHS, UCLA AS, Short form 12 score Treacy, 2011 Pre-op: none Follow up mean= 4 10.9 years 4/7 Post-op: Modified OHS, UCLA AS Hing, 2007 Pre-op: HHS, Flexion Follow-up means: 3 4 ROM years (2.1-43) and 5 3/7 years. Post-op: HHS, Flexion ROM Authur, year Results Comments Sackett Level, Quality score Back, 2005 Poorer outcomes of OHS, .86% failure rate. 4 HHS with lesser Charnley No radiographic 4/7 grade. component loosening. Mean flexion increased by 18.9 degrees. Kim,2007 Mean HHS IS improved 56 Lack of English 4 points. translation limited NA review. Valle, 2009. 32 major adverse events No outcomes 4 reported (10 femoral assessed. Study was 2/7 neck fractures, 8 designed to focus on dislocations, 9 nerve early post operative injuries, 5 other) risk. Steffen, 2007 Entire Croup: mean 20 revisions. 4 OHS=16.1, mean UCLA 92% of patients had a 3/7 AS=6.6 primary diagnosis of OA, 5 year follow-up group: mean OHS: 16.4, mean UCLA AS: 6.7. mean HHS 93,1, mean hip flexional = 105 degrees Treacy, 2005 HHS not clearly 6 revisions. 4 reported, but 87% had a 3/7 conclusions advocate preoperative diagnosis consideration of BHR for of hip OA. young, active patients. Heilpern, Mean HHS=96.4, Mean OHS 3.7% failure rate. 2008. improved 26.3 points. 4 UCLA AS improved 3.61 3/7 points. Madhu, 2009. mean OHS= 21.4 112-52), 6.8% failure rate. 4 Mean Harris Hip 63% had OA as 4/7 Score=84.8 (25-100), primary diagnosis. mean flexion AROM-100 degrees Reito, 2010. Mean HHS-95,3 3,3% failure rate. 4 3/7 Mean satisfaction-2,53 Narvani, 2006. Pre-op 65% were active Questionnaire not 4 in sports, post-up 92%. published. 3/7 Of those active in sports 92% felt their sporting function improved post op. Overall there was a significant difference in reported intensity and frequency of sports participation. Pollard, 2006. Post-op OHS mean=15.9 7H% of preoperative 4 (12-42), Post-op UCLA diagnosis was OA, 5/7 activity level was higher than THA group, mean=8,4 (4-10). Banerjee, Number of sports 3 revisions. 2010 patients participated 86% of the hip 4/7 in declined post op. resurfacings were Intermediate and high BHR, 91% had a impact sports decreased preoperative post op. Low impact diagnosis of OA. sports increased. One third of patients gave up sports they wanted to participate in. Malek, 2010 90% had the same 4 employment. 1/7 Rose, 2010 UCLA scores improvement 4,6% failure 4 were statistically 5/7 significant postoperatively Smet, 2002 HHS mean=97.24, hip 80% had a diagnosis 4 flexion mean=120.36 of OA 5/7 (90-240), 97,5% reported no pain Khan, 2009 HHS improved 2% failure rate, half 4 significantly occurring in first year 3/7 postoperatively, 95% extremely pleased or pleased Larbpaiboon- All measures improved 2.5% failure rate. pong, 2009 postoperatively 4 3/7 Treacy, 2011 Modified 0HS median= 6.5% revision rate. 4 4.2%. Median UCLA AS=7.0 patient selection 4/7 noted as "crucial" to success Hing, 2007 3 years: HHS improved 2,2% failure 4 significantly, mean 3/7 flexion improved significantly. 5 years: HHS deteriorated slightly, mean flexion remained same as 3 years N = number of hips, HHS=Harris Hip Score, OHS=Oxford Hip Score, UCLA AS: University of California Los Angeles Activity Score, ROM-range of motion, NA=not assessed (1) A = Systematic Review of Randomized Controlled Trials (RCTs) / 1B = RCTs with Narrow Confidence Interval / 1C = All or None Case Series / 2A = Systematic Review Cohort Studies / 2B = Cohort Study/Low Quality RCT/ (2) C = Outcomes Research / 3A = Systematic Review of Case-Controlled Studies / 3B = Case-controlled Study / 4 = Case Series, Poor
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|Publication:||Asian Journal of Sports Medicine (AsJSM)|
|Date:||Mar 1, 2012|
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