Resurfacing versus conventional total hip arthroplasty: review of comparative clinical and basic science studies.
Abstract: Objective: Although standard total hip arthroplasties have a long and successful history as the standard of care for advanced, symptomatic osteoarthritis, there is increasing patient demand and surgeon interest in femoral bone-conserving resurfacing alternatives. The purpose of this study was to assess the state of the research that directly compares the outcomes of conventional total hip arthroplasty procedures with the current generation of metal-on-metal resurfacing hip arthroplasties.

Methods: A comprehensive review was performed of the published literature that directly compared total hip arthroplasty and resurfacing hip arthroplasty and that considered basic science, radiographic, and clinical studies.

Results: Of the basic science studies, two investigations found evidence that favored total hip arthroplasty, while three favored resurfacing hip arthroplasty. For the clinical studies, all reports showed that resurfacing hip arthroplasty had similar or better outcomes than total hip arthroplasty at short- to midterm follow-up. The gait studies suggest that resurfacing provides a more natural gait than conventional total hip arthroplasty.

Conclusions: While there is still much debate and room for additional research on this topic, multiple midterm clinical results suggest that resurfacing hip arthroplasty represents a safe, effective alternative to conventional total hip arthroplasty, especially for younger, active patients.
Article Type: Clinical report
Subject: Osteoarthritis (Research)
Medical research
Medicine, Experimental
Authors: Marker, David R.
Strimbu, Kyle
McGrath, Mike S.
Zywiel, Michael G.
Mont, Michael A.
Pub Date: 04/01/2009
Publication: Name: Bulletin of the NYU Hospital for Joint Diseases Publisher: J. Michael Ryan Publishing Co. Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2009 J. Michael Ryan Publishing Co. ISSN: 1936-9719
Issue: Date: April, 2009 Source Volume: 67 Source Issue: 2
Topic: Event Code: 310 Science & research
Product: Product Code: 8000200 Medical Research; 9105220 Health Research Programs; 8000240 Epilepsy & Muscle Disease R&D NAICS Code: 54171 Research and Development in the Physical, Engineering, and Life Sciences; 92312 Administration of Public Health Programs
Accession Number: 247449421
Full Text: Modern total hip arthroplasty (THA) designs and surgical approaches have shown excellent long-term results for the treatment of late-stage symptomatic osteoarthritis, especially in older, less active patients. Some concerns exist that THA may provide less optimal outcomes in younger and more active patients. As such, there has long been an interest in more boneconserving replacement procedures, such as resurfacing hip arthroplasty (RHA). Earlier generations of hip resurfacing devices frequently failed, largely due to problems with excessive wear of their bearing surface materials. Since that time, improvements in surgical technique and design, specifically the introduction of thinner shelled metal-on-metal interfaces with improved tolerances, have led to a renewed and growing interest and use of resurfacing, especially in young and active patients.

Since the introduction of metal-on-metal resurfacing devices, in the 1990s, over 300,000 procedures have been performed worldwide. (1) Multiple studies of short- and midterm outcomes of resurfacing implants have reported clinical success rates upwards of 94%, (2) with several studies reporting five-year survival rates of 98%. (3,4) These outcomes are similar to those that have been reported for patients treated with conventional THA. Some investigators have argued that resurfacing may offer advantages over THA, in terms of conservation of femoral bone stock, increased range of motion (ROM), a more normal gait pattern, lower dislocation rates, and ease of revision. In order to assess these claims, a number of investigators have conducted studies directly comparing THA and RHA. These studies have varied in their approach in terms of the outcome parameters used to assess THA and RHA.

The purpose of the present study was to provide a comprehensive meta-analysis of the current literature that has directly compared modern RHA with conventional THA. Our primary question was: How do the outcomes for RHA

patients compare to their counterparts who receive a THA? More specifically, we asked what evidence is there in the current literature to answer the following questions: 1. Do RHA and THA provide similar biomechanics? 2. Are there advantages for RHA over THA, based on gait studies? 3. Are the radiographic outcomes similar for RHA and THA patients? 4. Are the clinical outcomes similar? and 5. Are the outcomes of patients who require revision of RHA to THA similar to patients receiving a primary THA?

Materials and Methods

We conducted a comprehensive, systematic review of the published medical literature, searching for reports on studies directly comparing conventional THA procedures and modern metal-on-metal RHA procedures. We used as our starting point keyword searches for the terms "total hip arthroplasty" and "hip resurfacing," and then narrowed our review to include only articles that considered the outcomes of both procedures in either a clinical or basic science comparison study. We searched the bibliographies of all relevant studies and related review articles to find additional pertinent studies. In addition, we reviewed the most recent Proceedings of the American Academy of Orthopaedic Surgeons (February 2008) to identify any THA versus RHA comparison studies from that conference.

Additional inclusion criteria were: 1. Only studies published in the past 10 years that provided results for modern RHA prostheses designs were included. For example, we excluded studies similar to those by Amstutz and colleagues5 and Gore and coworkers6 that were published in 1984 and 1985, respectively. 2. Similarly, we did not include studies (such as an article by Meldrum and associates7) that were published recently but provided long-term results of prior generation hip resurfacing designs. 3. We included the translated abstracts from papers published in foreign languages but not any additional content from the articles. Finally, 4. Only the most recent outcomes were used for patient cohorts from a given institution. For example, if a patient cohort was initially reported in the Proceedings of the American Academy of Orthopaedic Surgeons, but later published in a journal, then only the recent journal article was included in our analysis.

In order to answer the primary questions of our study, we stratified the studies into five categories. The first category consisted of the basic science papers. These investigations included any reports comparing THA and RHA in cadavers, composite models, or computer simulations, as well as any combination thereof. Gait analysis studies were stratified separately from the other basic science categories. The remaining categories included: comparative studies assessing radiographic parameters and outcomes, studies of clinical outcomes, and studies comparing the conversion of failed resurfacings to primary conventional THA.

Initially, attempts were made to aggregate the reported outcomes from the studies for each of the categories (basic science, gait analysis, radiographic evaluations, clinical outcomes, and revision RHA outcomes). However, due to differences in the outcome measures used in the various studies, it was determined that only limited aggregation was possible, making a statistical analysis invalid. Rather than aggregating the outcome measures, we identified how many studies in each of the categories reported statistically significant differences that favored THA or RHA, or showed similar outcomes.

Results

Basic Science Studies

There were five basic science studies that compared THA and RHA (Table 1). These studies focused on differences in natural joint biomechanics (such as ROM), amount of bone preservation, and bone strain-sheer. Two of these studies favored THA, while three favored RHA.

Comparing a Durom metal-on-metal resurfacing prosthesis to a conventional Metasul metal-on-metal THR prosthesis via finite element models of the two designs, Liu and colleagues reported findings that favor THR. (8) They reported that that the maximum contact pressures were 22 MPa for a Durom[TM] RHA, compared to 47 MPa for a Metasul[TM] THA. These correlated to a contact area of 237 mm2 versus 74 m[m.sup.2] for the RHA and THA, respectively. With respect to ROM, two studies [a three-dimensional computer model study that assessed composites of computed tomography (CT) scans by Doherty and coworkers (9) and an in-vitro study by Bengs and Associates (10)] reported that RHA leads to a decreased ROM, compared to THA when utilizing a bone-only model. In the other two basic science studies, Deuel and colleagues (11) used microstrains in a cadaver model to demonstrate that RHA preserves femoral bone stock, and Su and coworkers (12) reported that RHA not only preserves substantially more femoral bone, but also can be implanted with an acetabular bone loss similar to that of THA.

Radiographic Studies

There were seven studies that compared radiographic parameters for THA and RHA (Table 2). Some of the outcome measures for these studies included leg length, femoral offset, size of components to estimate bone loss, and incidence of heterotopic ossification. The majority of these studies (n = 4) suggested that THA provided better outcomes compared to RHA. Of the remaining studies, one indicated there was no significant difference between these two surgical approaches, and two studies suggested RHA provided better outcomes.

There were three studies that assessed changes in leg length and femoral offset following hip arthroplasty, with conflicting outcomes. Two studies reported that negative horizontal femoral offset and greater leg-length changes made RHA less biomechanically accurate. (13,14) In contrast, in the cohort for Girard and associates, leg-length inequality was restored in 60% of THA versus 86% for RHA. (15)

Two studies focused on acetabular bone loss as a measure of biomechanical restoration success. Loughead and associates reported that while femoral bone can be saved with RHA procedures, statistically significantly more acetabular bone is lost. However, similar to the basic science study by Su and colleagues, (12) Vendittoli and coworkers reported that with careful technique and appropriately-sized implant options, acetabular implants need be no larger in RHA patients than in THA patients, while also conserving femoral bone stock. (16)

Rama and associates used radiographic analysis to identify asymptomatic heterotopic ossification (HO) formation in postoperative RHA and THA patients. (17) They found that RHA patients had a significantly higher rate of severe (Booker grades 3 and 4) HO formation than THA patients (12.6% compared to 2.1%), with Booker grade 4 HO found only in RHA patients.

Clinical Studies

Nine reports compared the short- and midterm clinical results of the two procedures (Table 3). The majority of the investigations demonstrated that the two prostheses had similar clinical hip scores and revision rates. However, five studies also found that patients who underwent RHA had higher postoperative activity levels than patients who underwent THA. Additional findings included lower dislocation rates associated with resurfacing and conflicting results regarding ROM.

Vail and colleagues compared 52 patients (57 hips) who underwent RHA to 84 patients (93 hips) who underwent conventional THA.18 At a mean follow-up of three years (range, 2 to 4 years), the resurfacing cohort had significantly higher Harris hip scores than the conventional arthroplasty cohort. The activity, function, and ROM subscores of the resurfacing cohort were all significantly greater as well. The complication rate of the conventional arthroplasty cohort was 14%, compared with a 5.3% complication rate in the resurfacing cohort. Complications in the THA cohort included fracture (two patients), deep venous thrombosis (three patients), dislocation (four patients), aseptic loosening (one patient), and intraoperative calcar fracture (three patients). Complications in the resurfacing cohort consisted of fracture (one patient), deep venous thrombosis (one patient), and joint infection (one patient).

Pollard and coworkers compared a group of 53 patients (54 hips) who received conventional THA with another group of 51 patients (54 hips) who had undergone RHA.2 The hips were matched by gender and age at surgery, body mass index (BMI), and preoperative activity level. At a mean follow-up of 80 months (range, 42 to 120 months) for the THA cohort and 61 months (range, 52 to 71 months) for the resurfacing cohort, the mean Oxford hip scores were similar. However, the patients who underwent resurfacing had significantly higher UCLA activity scores and EuroQol (quality of life) scores than their counterparts who underwent conventional THA.

Mont and associates compared two matched groups of 54 patients, who had undergone either conventional THA or metal-on-metal RHA. (19) The patients were matched by age, gender, diagnosis, BMI, preoperative Harris hip score, and length of follow-up. At a mean follow-up of 40 months (range, 24 to 60 months), the Harris hip, pain, and satisfaction scores were similar, but the patients who underwent resurfacing had higher activity scores. The investigators concluded that the higher postoperative activity scores may have been a result of selection bias, as the resurfacing cohort also had a significantly higher mean preoperative activity score, and patients who engaged in high activity levels preoperatively were more likely to request resurfacing.

Lavigne and colleagues conducted a randomized controlled study that compared 81 patients who underwent resurfacing with 71 patients who underwent conventional THA. (20) The functional results, satisfaction ratings, ROM scores, and complication rates were similar at the 1 year follow-up. However, the mean overall activity score of the resurfacing cohort was substantially higher than that of the THA group (p < 0.001), and a substantially higher number of patients who underwent resurfacing returned to moderate or high activity levels (77%), compared with patients who underwent conventional THA (39%). The preoperative activity levels of the two groups were similar, so the investigators concluded that the large head of the resurfacing prostheses might confer greater joint stability; this might be a factor that led to increased activity levels. In separate presentations, the same investigators reported that the patients who underwent resurfacing had significantly shorter hospital durations (6 vs 5 days), significantly lower rates of dislocation at the 24-month follow-up (0 vs 4 dislocations), and similar ranges of motion, compared with the patients who underwent conventional arthroplasty.

Stulberg and coworkers compared a group of 337 patients who underwent resurfacing with 266 patients who received conventional THA, and found that the patients who underwent resurfacing experienced pain for a longer postoperative period, but increased their functional status sooner than the patients who underwent conventional arthroplasties. (21) At 6 weeks following the procedure, the patients who underwent resurfacing reported a greater prevalence of pain, and so the Harris hip scores were significantly lower. However, the mean Harris hip function subscore was higher for the resurfacing group at the 6- and 12-month follow-up assessments, although the Harris hip scores of the two groups were not significantly different. By 24 months postoperatively, the two groups had similar functional scores, and the Harris hip scores were comparable.

Haddad and associates examined a series of tests of high-level hip function, including an unsupported single leg stance for one minute, unsupported step-ups onto 40-cm blocks, lateral step-ups, and a hop test. (22) The comparison of 40 patients who underwent resurfacing with 40 patients who received conventional THA revealed that the two groups had similar preoperative scores on all tests, but that the resurfacing cohort had dramatically higher scores on the hop test and both step-up tests at 6 weeks, as well as 2 years after the procedure.

Gait Studies

There were three gait studies and one study that assessed the postural balance in RHA and THA patients. All these studies showed similar or better outcomes for RHA compared to their THA counterparts.

In a retrospective, gender-matched study, Mont and colleagues compared the walking velocity as well as extensor and abductor moments of 15 patients who underwent RHA procedures to those of 15 patients who received THA procedures and 10 patients with osteoarthritis who were not treated surgically. (23) The study found that at a mean 13-month follow-up, patients in the RHA group walked faster and with more normal gaits by these measures than patients in either the THA group or the control group. Two more recent studies evaluated the gait patterns of RHA and THA patients using slightly different parameters. Lavigne and coworkers examined the distribution of energy genera tion and absorption in three groups of patients: RHA, THA with large-diameter heads, and THA with small-diameter heads. (24) They found that patients who received RHA and large-diameter head THA returned to more normal gait patterns than patients who had small-diameter femoral heads. Shimmin and associates compared RHA and THA patients who had Harris hip scores of 100 to age-matched asymptomatic control patients. (25) They reported that there was no significant difference in gait, at either fast walking or jogging paces, among any of the groups.

The postural balance study by Nantel and colleagues reported that THAs had greater medial to lateral centers of pressure and mass displacement during dual stance when compared to RHA (p < 0.05). (26) They suggested that these differences may be attributed to the larger bearing component for RHA and the better anatomical preservation when compared to THA.

Conversions of Failed Resurfacings

There were two studies that compared the outcomes of failed RHA procedures, then converted to conventional THAs, to patients who had primary conventional THA. These two studies, by Ball and coworkers (27) and McGrath and associates, (28) assessed the concept that revisions of resurfacings are comparable to primary THAs.

Ball and colleagues compared the revisions of 21 resurfacings (in 20 patients) to a group of 58 hips (in 64 patients) who had undergone primary THA, all by the same surgeon.27 They found no significant difference between the two groups in terms of operative blood loss, operative time, or complication rates. At mean follow-up times of 46 months for the conversion group and 57 months for the primary THA group, there were also no significant differences between the groups in terms of Harris hip scores; UCLA pain, walking, or activity subscores; or the SF-12 scores. Ball and coworkers concluded that claims of the ease, safety, and efficacy of surgical revision of resurfaced hips were justified.

McGrath and associates (28) compared the perioperative factors, complications, and clinical as well as radiographic outcomes of 39 patients whose resurfacings were converted to THA to a group of primary THA patients matched by gender, age, BMI, and preoperative Harris hip score, all performed by the same surgeon. They found mean operative time for the conversions were longer by 19 minutes, but all other perioperative measures were similar. At a mean followup of 45 months, the Harris hip scores of the two groups were similar (92 for the conversion group; 94 for the primary THA group). They also concluded that the conversion of failed resurfacings can be considered comparable procedures with similar outcomes to primary THAs.

Discussion

There are limitations to the present analysis that include the level of evidence of the studies reviewed, as there were few randomized, prospective trials. Another limitation is the length of follow-up for the studies. Conventional THA procedures have long-term data stretching past the 20-year mark. In contrast, the most recent generation of resurfacing devices has not yet been in use long enough to provide comparable long-term follow-up data. Despite these limitations, the early findings in these comparative studies appear promising and suggest that RHA provides similar and in some cases potentially improved outcomes compared to THA.

As research on the comparative efficacy of the two procedures continues, attention should be paid, in particular, to the types of measures used to evaluate the outcomes. As some investigators have begun to hypothesize, including Haddad and colleagues, (22) the measures traditionally used to evaluate THA outcomes might not be as effective at distinguishing between the outcomes of the two procedures. If, as some surgeons suggest, resurfacing returns patients earlier to higher activity levels, more challenging clinical tests of function might be necessary to see the true comparative benefits and limitations of each procedure.

In summary, there is renewed and growing interest in the current generation of RHA on the part of both surgeons and patients. Based on this interest, there have been a number of studies in the last decade that have been conducted to directly compare the outcomes of this procedure to THA. Our review of this literature suggests that basic science, radiographic, clinical, and gait outcomes are similar between the two procedures.

Disclosure Statement

Michael A. Mont, M.D., is a consultant for Stryker Orthopedics and Wright Medical Technology. The other authors certify that they have no commercial associations (e.g., consultancies, stock ownership, equity interest, patent and licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article. Each author certifies that his or her institution has approved the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.

References

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(2.) Pollard TC, Baker RP, Eastaugh-Waring SJ, Bannister GC. Treatment of the young active patient with osteoarthritis of the hip. A five- to seven-year comparison of hybrid total hip arthroplasty and metal-on-metal resurfacing. J Bone Joint Surg Br. 2006;88:592-600.

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(4.) Hing CB, Back DL, Bailey M, et al. The results of primary Birmingham hip resurfacings at a mean of five years. An independent prospective review of the first 230 hips. J Bone Joint Surg Br. 2007;89:1431-8.

(5.) Amstutz HC, Thomas BJ, Jinnah R, et al. Treatment of primary osteoarthritis of the hip. A comparison of total joint and surface replacement arthroplasty. J Bone Joint Surg Am. 1984;66:228-41.

(6.) Gore DR, Murray MP, Gardner GM, Sepic SB. Hip function after total vs. surface replacement. Acta Orthop Scand. 1985;56:386-90.

(7.) Meldrum RD, Maiers GP 2nd, Feinberg JR, et al. Long-term outcome of surface replacement with comparison to an ageand time-matched primary total hip arthroplasty cohort. J Arthroplasty. 2008;23:1-9.

(8.) Liu F, Udofia IJ, Jin ZM, et al. Comparison of contact mechanics between a total hip replacement and a hip resurfacing with a metal-on-metal articulation. Proceedings of the Institution of Mechanical Engineers, Part C. J Mech Eng Sci. 2009:727-32.

(9.) Doherty SR, Thompson MT, Usrey MM, et al. Does hip resurfacing restore normal range of motion and provide better joint motion than THR? Presented at: The 53rd Annual Meeting of the Orthopedic Research Society; February 11-14, 2007; San Diego, California, paper #0276.

(10.) Bengs BC, Sangiorgio SN, Ebramzadeh E. Less range of motion with resurfacing arthroplasty than with total hip arthroplasty: in vitro examination of 8 designs. Acta Orthop. 2008;79:755-62.

(11.) Deuel CR, Jamali AA, Stover SM, Hazelwood SJ. Alterations in femoral strain following hip resurfacing and total hip replacement. J Bone Joint Surg Br. 2009;91:124-30.

(12.) Su EP, Sheehan M, Su SL. Comparison of Bone Removed During Total Hip Arthroplasty With a Resurfacing or Conventional Femoral Component A Cadaveric Study. J Arthroplasty. 2008; Epub Dec 2 ahead of print.

(13.) Loughead JM, Chesney D, Holland JP, McCaskie AW. Comparison of offset in Birmingham hip resurfacing and hybrid total hip arthroplasty. J Bone Joint Surg Br. 2005;87:163-6.

(14.) Silva M, Lee KH, Heisel C, et al. The biomechanical results of total hip resurfacing arthroplasty. J Bone Joint Surg Am. 2004;86:40-6.

(15.) Girard J, Lavigne M, Vendittoli PA, Roy AG. Biomechanical reconstruction of the hip: a randomised study comparing total hip resurfacing and total hip arthroplasty. J Bone Joint Surg Br. 2006;88:721-6.

(16.) Vendittoli PA, Lavigne M, Girard J, Roy AG. A randomised study comparing resection of acetabular bone at resurfacing and total hip replacement. J Bone Joint Surg Br. 2006;88:997 1002.

(17.) Rama KR, Vendittoli PA, Ganapathi M, et al. Heterotopic ossification after surface replacement arthroplasty and total hip arthroplasty: a randomized study. J Arthroplasty. 2009;24:256 62.

(18.) Vail TP, Mina CA, Yergler JD, Pietrobon R. Metal-on-metal hip resurfacing compares favorably with THA at 2 years follow-up. Clin Orthop Relat Res. 2006;(453):123-31.

(19.) Mont MA, Marker DR, Smith JM, et al. Resurfacing is comparable to total hip arthroplasty at short-term follow-up. Clin Orthop Relat Res. 2009;(467):66-71.

(20.) Lavigne M, Masse V, Girard J, et al. [Return to sport after hip resurfacing or total hip arthroplasty: a randomized study]. Rev Chir Orthop Reparatrice Appar Mot. 2008;94:361-7. [French]

(21.) Stulberg BN, Fitts SM, Bowen A. Early return to function after hip resurfacing. Is it better than contemporary THA? Proceedings of the 75th Annual American Academy of Orthopaedic Surgeons Meeting; March 5-9, 2008; San Francisco, California, p. 383.

(22.) Haddad FS, Bull J. Hip resurfacing has superior sustained functional outcomes when compared to total hip arthroplasty. Proceedings of the 75th Annual American Academy of Orthopaedic Surgeons Meeting; March 5-9, 2008; San Francisco, California, p. 428.

(23.) Mont MA, Seyler TM, Ragland PS, et al. Gait analysis of patients with resurfacing hip arthroplasty compared with hip osteoarthritis and standard total hip arthroplasty. J Arthroplasty. 2007;22:100-8.

(24.) Lavigne M, Vendittoli PA, Nantel J, Prince F. Gait analysis in three types of hip replacement. Proceedings of the 75th Annual American Academy of Orthopaedic Surgeons Meeting; March 5-9, 2008; San Francisco, California, p. 431.

(25.) Shimmin AJ, Bennell K, Wriglet T, et al. Gait analysis comparison of the functional outcome of hip resurfacing and total hip replacement. Proceedings of the 75th Annual American Academy of Orthopaedic Surgeons Meeting; March 5-9, 2008; San Francisco, California, p. 382.

(26.) Nantel J, Termoz N, Centomo H, et al. Postural balance during quiet standing in patients with total hip arthroplasty and surface replacement arthroplasty. Clin Biomech (Bristol, Avon). 2008;23:402-7.

(27.) B all ST, Le Duff MJ, Amstutz HC. Early results of conversion of a failed femoral component in hip resurfacing arthroplasty. J Bone Joint Surg Am. 2007;89:735-41.

(28.) McGrath MS, Marker DR, Seyler TM, et al. Surface replacement is comparable to primary total hip arthroplasty. Clin Orthop Relat Res. 2009;(467):94-100.

(29.) Loughead JM, Starks I, Chesney D, et al. Removal of acetabular bone in resurfacing arthroplasty of the hip: a comparison with hybrid total hip arthroplasty. J Bone Joint Surg Br. 2006;88:31-4.

(30.) Girard J, Vendittoli PA, Roy AG, Lavigne M. [Femoral offset restoration and clinical function after total hip arthroplasty and surface replacement of the hip: a randomized study]. Rev Chir Orthop Reparatrice Appar Mot. 2008;94:376-81. [French]

(31.) Lavigne M, Vendittoli P, Roy A, Lusignan D. A randomized study comparing surface replacement arthroplasty to total hip arthroplasty. Proceedings of the 75th Annual American Academy of Orthopaedic Surgeons Meeting; March 5-9, 2008; San Francisco, California, p. 384.

(32.) Lavigne M, Mottard S, Girard J, Vendittoli PA. Range of motion after hip resurfacing and THA: a single-blind randomized clinical study. Proceedings of the 75th Annual American Academy of Orthopaedic Surgeons Meeting; March 5-9, 2008; San Francisco, California, p. 384-5.

David R. Marker, B.S., Kyle Strimbu, B.S., Mike S. McGrath, M.D., Michael G. Zywiel, M.D., and Michael A. Mont, M.D., are from the Rubin Institute for Advanced Orthopedics, Center for Joint Preservation and Reconstruction, Sinai Hospital of Baltimore, Baltimore, Maryland.

Correspondence: Michael A. Mont, M.D., Rubin Institute of Advanced Orthopedics, Center for Joint Preservation and Reconstruction, Sinai Hospital of Baltimore, 2401 West Belvedere Avenue, Baltimore, Maryland 21215; mmont@lifebridgehealth.org.

David R. Marker, B.S., Kyle Strimbu, B.S., Mike S. McGrath, M.D., Michael G. Zywiel, M.D., and Michael A. Mont, M.D.
Table 1 Literature Review of Basic Science Studies that Compared
Resurfacing and Conventional Total Hip Arthroplasty

Authors           Design                 Outcomes

Liu, et al.       Three-dimensional      RHA has less contact
(2005) (8)        finite element         pressure (-53%) and
                  analysis               increased contact
                                         area (+220%).

Doherty, et al.   Three-dimensional CT   Flexion and
(2007) (9)        computer models        extension: RHA =
                                         109[degrees] and
                                         13[degrees] vs THA =
                                         125[degrees] and
                                         34[degrees].

Bengs, et al.     In vitro comparison    Conventional THA
(2008) (10)       of 8 different RHA     allowed for
                  or THA prosthetic      statistically
                  models                 significantly
                                         greater range of
                                         motion than RHA.

Deuel, et al.     In vitro cadaver       Microstrain of 621
(2008) (11)       models                 for native femurs
                                         was similar to RHA
                                         but not THA.

Su, et al.        In vitro cadaver       Femoral bone loss:
(2009) (12)       models                 RHA = 26 g vs THA =
                                         75 g (p < 0.001).
                                         Acetabular bone
                                         loss: RHA = 26 g vs
                                         THA = 75 g (p =
                                         0.60).

Authors           Conclusions            Advantage

Liu, et al.       RHA may have less      RHA
(2005) (8)        wear debris and
                  better long-term
                  outcomes than THA.

Doherty, et al.   RHA has a reduced      THA
(2007) (9)        range of motion.

Bengs, et al.     RHA has a reduced      THA
(2008) (10)       range of motion due
                  to impingement.

Deuel, et al.     Bone strain for RHA    RHA
(2008) (11)       are more similar to
                  the native femur
                  than THA.

Su, et al.        RHA leads to less      RHA
(2009) (12)       femoral bone loss
                  and similar
                  acetabular bone loss
                  compared to THA.

Table 2 Literature Review of Studies Comparing Radiographic Data
for Resurfacing and Conventional Total Hip Arthroplasty

Study              Procedure   Hips   Outcomes

Silva, et al.      THA         40     Leg length change:
(2004) (14)                           -1.1 mm Horizontal
                                      femoral offset
                                      change: = +5.2 mm

                   RHA         50     Leg length change:
                                      RHA = -2.2 mm.
                                      Horizontal femoral
                                      offset change: -8.4
                                      mm

Loughead, et al.   THA         26     Hip length increase:
(2005) (13)                           0.3 mm

                   RHA         28     Hip length increase:
                                      3.6 mm

Girard, et al.     THA         55     Leg length
(2006) (15)                           inequality restored
                                      in 60% of hips

                   RHA         49     Leg length
                                      inequality restored
                                      in 86% of hips

Loughead, et al.   THA         33     Mean acetabulum
(2006) (29)                           size: 52 mm
                                      (Acetabular size
                                      difference was
                                      greater than the
                                      femoral head size
                                      difference)

                   RHA         35     Mean acetabulum
                                      size: 56.4 mm

Vendittoli, et     THA         103    Acetabulum size:
al. (2006) (16)                       54.74 mm

                   RHA         102    Acetabulum size:
                                      54.90 mm

Girard, et al.     THA         79     Horizontal femoral
(2008) (30)                           offset change: +4.2
                                      mm

                   RHA         69     Horizontal femoral
                                      offset change: -2.8
                                      mm

Rama, et al.       THA         99     Brooker grades 3 and
(2008) (17)                           4 HO: 2.1%

                                      Brooker grade 4 HO:
                                      0%

                   RHA         105    Booker grades 3 and
                                      4 HO: 12.6%

                                      Booker grade 4 HO:
                                      4.9%

Study              Conclusions            Advantage

Silva, et al.      THA may allow better   THA
(2004) (14)        biomechanical
                   reconstruction for
                   patients with leg-
                   length inequalities
                   >10 mm or low
                   femoral offset.

Loughead, et al.   THA results in         THA
(2005) (13)        biomechanics that
                   more accurately
                   resemble a normal
                   hip.

Girard, et al.     Hip biomechanical      RHA
(2006) (15)        reconstruction is
                   more precisely
                   achieved through
                   RHA.

Loughead, et al.   Patients requiring     THA
(2006) (29)        larger femoral heads
                   will have
                   statistically
                   significantly more
                   acetabular bone loss
                   for RHA compared to
                   THA.

Vendittoli, et     RHA conserves          RHA
al. (2006) (16)    femoral bone stock
                   and can maintain
                   similar acetabular
                   bone stock compared
                   to THA with proper
                   surgical technique.

Girard, et al.     RHA had decline in     Similar
(2008) (30)        horizontal femoral
                   offset but this did
                   not affect clinical
                   function.

Rama, et al.       RHA may require HO     THA
(2008) (17)        prophylaxis and
                   surgeons should use
                   meticulous surgical
                   technique.

Table 3 Literature Review of Studies Comparing Clinical Data
for Resurfacing and Conventional Total Hip Arthroplasty

                           No. of    Follow-
                          patients      up
Study         Procedure    (hips)    (months)

Pollard,      THA         54 (54)    80
et al.
(2006) (2)

              RHA:        54 (54)    61

Vail,         THA         84 (93)    36
et al.
(2006) (18)

              RHA         52 (57)    36

Girard,       THA         79         --
et al.
(2008) (30)
              RHA         69         --

Haddad,       THA         40 (40)    24
et al.
(2008) (22)

              RHA         40 (40)    24

Lavigne,      THA         103        24
et al.
(2008) (31)

              RHA         107        24

Lavigne       THA         71 (71)    12
et al.
(2008) (20)

              RHA         81 (81)    12

Lavigne       THA         62         12 (min)
et al.
(2008) (32)

              RHA         60         12 (min)

Stulberg      THA         266        24
et al.                    (266)
(2008) (21)
              RHA         337        24
                          (337)

Mont          THA         54 (54)    39
et al.
(2009) (19)

              RHA         54 (54)    39

                                          Complication
                                          and
              Mean clinical scores in     Reoperation
Study         points (range)              rates

Pollard,      OHS: 18.5 (12-41)           8%
et al.        UCLA: 6.8 (3-10)
(2006) (2)

              OHS: 15.9 (12-42)           6%
              UCLA: 8.4 (4-10)

Vail,         HHS: 93                     Reoperation:
et al.        Activity score: 12.7        4.3%
(2006) (18)

                                          Complication:
                                          14%

              HHS: 98                     Reoperation:
              Activity subscore: 14       3.5%
                                          Complication:
                                          5.3%

Girard,       P-M: 17 [+ or -] 0.4        --
et al.        WOMAC: 11.7 [+ or -] 11.4
(2008) (30)
              P-M: 17 [+ or -] 0.35       --
              WOMAC: 9.2 [+ or -] 15.1

Haddad,       Hop test: 0.03 meters       --
et al.        3 step-ups in 15 seconds
(2008) (22)
              Lateral step score:
              2.5 (3 = poor)

              Hop test: 0.32 meters       --
              7 step-ups in 15 seconds

              Lateral step score:
              0.7 (3 = poor)

Lavigne,      Hospital length of stay:    Isolated
et al.        6.1 days                    dislocations
(2008) (31)                               in 3 hips. 1
                                          revision for
                                          recurrent
                                          dislocation.

              Hospital length of stay:    2 revisions for
              5.0 days                    head collapse

Lavigne       Overall activity:           --
et al.          12.7 points
(2008) (20)   WOMAC: 9.8 [+ or -]
                10.9 points
              UCLA: 6.75 [+ or -]
                1.71 points

              Overall activity:           --
                17.9 points
              WOMAC: 8.1 [+ or -]
                13.1 points
              UCLA: 7.17 [+ or -]
                2.8 points

Lavigne       Total arc of motion:        --
et al.          196[degrees]
(2008) (32)   Arc of rotation:
                44.3[degrees]
              Flexion-extension
                arc:120[degrees]
              Abduction-adduction
                arc: 43[degrees]

              Total arc of motion:        --
                204[degrees]
              Arc of rotation:
                48[degrees]
              Flexion-extension
                arc:118[degrees]
              Abduction-adduction
                arc: 43[degrees]

Stulberg      --                          --
et al.
(2008) (21)
              --                          --

Mont          HHS: 91 (62-100)            Two revisions
et al.        Satisfaction: 8.8 (0-10)
(2009) (19)   Activity: 7 (0-20)

              HHS: 90 (50-100)            Two revisions
              Satisfaction: 9.2 (2-10)
              Activity: 11.7 (0-32)

Study         Conclusions            Advantage

Pollard,      Similar Oxford Hip     RHA
et al.        Scores and failure
(2006) (2)      rates.

              Resurfacing
              associated with
              higher activity
              levels.

Vail,         RHA associated with    RHA
et al.        significantly higher
(2006) (18)   HHS,

              ROM subscore,
              activity subscore,
              and function
              subscore.

Girard,       Similar clinical       Similar
et al.        scores.
(2008) (30)

Haddad,       Resurfacing            RHA
et al.        associated with
(2008) (22)   higher levels of
              function at all
              follow-up times.

Lavigne,      Similar clinical       Similar
et al.        scores, satisfaction
(2008) (31)   rates, and
              complication rates.
              THA was associated
              with higher
              dislocation rates.

Lavigne       Pre-operative          RHA
et al.        activity scores of
(2008) (20)   the two groups were
              similar. RHA
              associated with more
              frequent and more
              intense sports
              activities
              postoperatively.

Lavigne       No statistically       Similar
et al.        significant range-
(2008) (32)   of-motion
              differences were
              found between THA
              and RHA patients.

Stulberg      RHA: greater pain      Similar
et al.        score (and lower
(2008) (21)   HHS) at 6 weeks. HHS
              statistically
              similar at 6, 12,
              and 24 months.

Mont          Midterm clinical       Similar
et al.        outcomes and
(2009) (19)   satisfaction scores
              similar.

              Resurfacing patients
              had higher activity
              scores, but also had
              higher preop
              activity scores.

Abbreviations: THA, total hip arthroplasty; RHA, resurfacing hip
arthroplasty; OHS, Oxford hip score; UCLA, University of
California at Los Angeles Activity Score; HHS, Harris Hip Score,
ROM, range of motion; P-M, Postel-Merle-d'Aubigne score; WOMAC,
Western Ontario and McMaster Universities Osteoarthritis Index.
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