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The Journal of Arthroplasty Vol. 27 No. 1 2012

Hip Resurfacing Arthroplasty inInflammatory Arthritis

A 3- to 5-Year Follow-up Study

Rajesh Malhotra, MS, Arun Kannan, MS, Vijay Kumar, MS,Chethan Nagaraj, MS, Kanniraj Marimuthu, MS, and Dharmesh Khatri, MS

Abstract: The success of hip resurfacing in younger patients with primary osteoarthritis has pavedthe way for the trial of the procedure in patients with secondary osteoarthritis of the hip. Weretrospectively reviewed the clinical and radiologic results in a cohort of 23 patients (32 hips) withinflammatory arthritis who were chosen for hip resurfacing after normalizing vitamin D levels andruling out proximal femoral osteopenia using dual-energy x-ray absorptiometry. At a minimumfollow-up of 3 years, there was failure in only 1 hip due to fracture of the femoral neck attributableto osteonecrosis of the remnant head. The clinical outcome was evaluated using Harris hip scoreand was found to be good to excellent in 30 of 31 hips. Hip resurfacing is a promising alternative incarefully chosen patients with inflammatory arthritis. Keywords: hip resurfacing, inflammatoryarthritis, metal-on-metal, bone mineral density, vitamin D.© 2012 Elsevier Inc. All rights reserved.

Patients with inflammatory arthritis requiring hiparthroplasty are younger than their counterparts withosteoarthritis undergoing hip arthroplasty and are likelyto outlive their implant. Hip resurfacing, which providesfor preservation of the proximal femoral bone stock,better bone mineral density of the proximal femur [1],technically easier revision surgery [2,3], and reduceddislocation rates [4], theoretically, is a suitable alterna-tive to “stemmed hip arthroplasty” in this subset ofpatients. The better range of motion (ROM) at the hipafforded by the large-diameter metal-on-metal articula-tion [5,6] would be particularly beneficial in patientswith stiff spines. In addition, greater stability withconsequent reduction in the possibility of dislocationallows early and confident mobilization of the hip andaids in attaining the best improvement in the ROM.However, patients with inflammatory arthritis presentunique challenges to arthroplasty. Although problemssuch as operative positioning, unpredictable gain in

the Department of Orthopaedics, All India Institute of Medicalew Delhi, India 110029.tted June 22, 2010; accepted February 7, 2011.nflict of Interest statement associated with this article can bedoi:10.1016/j.arth.2011.02.016.t requests: Arun Kannan, MS, Department of Orthopaedics,Institute of Medical Sciences, New Delhi 110029, India.2 Elsevier Inc. All rights reserved.403/2701-0003$36.00/0.1016/j.arth.2011.02.016

15

ROM, heterotopic ossification, and influence of drugtherapy (steroids and DMARDS) are common to bothconventional total hip arthroplasty (THA) and resurfa-cing in patients with inflammatory arthritis, problemssuch as proximal femoral osteopenia and difficulty withsurgical dislocation assume greater significance inresurfacing arthroplasty. However, short-term resultsin patients with ankylosing spondylitis have beenencouraging [6]. We describe the results of total hipresurfacing done for inflammatory arthritis of the hip ata mean follow-up of 43 months (range, 36-56 months).

Materials and MethodsA retrospective review of the patients who underwent

hip resurfacing between January 2004 and August 2006revealed 49 hip resurfacings in 37 patients. Of these, 32hips in 23 patients were resurfaced for disablinginflammatory arthritis of the hip. Painful or stiff jointshindering activities of daily living were the primaryindication for hip resurfacing. The serum level of 25(OH)D3 was estimated in all patients before resurfacingbecause of the association of vitamin D deficiency withankylosing spondylitis [7,8] and rheumatoid arthritis[9,10], and also known high prevalence of the deficiencyin our population [11]. Those with suboptimal 25(OH)Dlevels (b75 nmol/L) [12] were treated with 50 000 IUvitamin D weekly for 4 weeks followed by 1000 IU dailyfor 2 months. In addition, 1000 mg elemental calciumper day and 70 mg alendronate per week were initiated.

Table 1. Demographic Profile

No. of hips 32No. of patients 23Male 16Female 7Mean BMI 23.5 kg/m2

Mean age 33 years

16 The Journal of Arthroplasty Vol. 27 No. 1 January 2012

At the end of this period, the proximal femoral bonemineral density was assessed using dual-energy x-rayabsorptiometry. Resurfacing was offered only to thosewith T score greater than −1.0 and normal 25(OH)Dlevels. Patients who required steroids to maintainremission were excluded. Technetium bone scintigraphywas done in all patients to rule out osteonecrosis.Patients with areas of necrosis greater than 1 cm indiameter were excluded.Thirty-two hips of 23 patients with inflammatory

arthritis who had undergone resurfacing, with aminimum follow-up of 3 years, were analyzed. Twen-ty-one hips of 15 patients had a diagnosis of ankylosingspondylitis, 9 hips of 6 patients had rheumatoid arthritis,and 2 were seronegative for spondyloarthropathy.Clinical and radiologic details were retrieved and

analyzed. The preoperative symptoms, ambulatorystatus, need for walking aids, ROM, Harris hip score[13], and status of the other joints were recorded.Intraoperative details were gathered.All the cases were operated through the posterior

approach. The short external rotators were divided 1 cmaway from their insertion, and the quadratus femoriswas preserved wherever possible. Ankylosed hips,which could not be dislocated after adequate capsularrelease and manipulation, were considered unsuitablefor resurfacing, and accordingly, conventional THA wascarried out. The articular surface replacement (ASR)system (DePuy International Ltd, Leeds, UK) was used.The acetabular component was implanted with press-fitby under reaming the acetabulum. All femoral compo-nents were cemented. Suction was applied through avent at the level of the lesser trochanter, before cementapplication.Low-molecular-weight heparin was used for throm-

boprophylaxis in the postoperative period. Weight-bearing and functional exercises were initiated on thesecond postoperative day. Intravenous cefotaxime wasinitiated just before surgery and was continued postop-eratively for 5 days. Methotrexate was administeredperioperatively in patients with rheumatoid arthritis.Patients with ankylosing spondylitis were given 75 mgindomethacin per day for 2 weeks postoperatively toprevent heterotopic ossification. In addition, the patientswere administered elemental calcium in the dose of1000 mg and vitamin D 1000 IU per day and 70 mg ofalendronate per week for a minimum of 2 years.All patients were contacted through telephone and

were requested to report to the outpatient for follow-up.Clinical assessment included evaluation of the pain,function, deformities, and ROM using the Harris hipscore. A Harris hip score of 90 points or more wasdefined as an excellent outcome; 80 to 89 points, a goodoutcome; 70 to 79 points, a fair outcome; and less than70 points, a poor outcome. The sum ROM wasmeasured. This refers to the sum of flexion, extension,

abduction, adduction, and internal rotation and externalrotation movements achieved by the patient.Radiographic evaluation comprising anteroposterior

radiographic views of the pelvis, including the hips and alateral view of the hip, was performed during follow-up.The femoral lucencies were evaluated radiographicallyusing the system of Amstutz et al [14]. Inclination of thefemoral stem was measured by the angle between thestem of the femoral component and the femoral shaftand compared with the preoperative neck-shaft angle.Greater than 5° variation of the femoral inclination fromthe neck-shaft angle was considered excess varus orvalgus inclination. Subsidence of the femoral compo-nent was measured as described by Ramakrishnan et al[15]. Acetabular lucencies were evaluated using thecriteria of DeLee and Charnley [16]. Ectopic ossificationwas graded according to the system described byBrooker et al [17].Statistical analysis was done using the SPSS software

(SPSS, Chicago, Ill), with the Student t test being used toestimate significance of difference in means. All P valuesless than .05 were considered significant.

ResultsThe demographic profile of the patients is listed in

Table 1. The mean age of study cohort of young adultswas 33 years, with a range of 21 to 48 years.Preoperatively, 4 of the patients were bedridden,whereas the rest were ambulatory, dependent onwalking aids. Twenty-two of the 23 patients hadsuboptimal 25(OH)D levels and had undergone vitaminD therapy before resurfacing. Nine patients underwentbilateral hip resurfacing, of which 7 underwent single-stage resurfacing, whereas 2 patients were subjected to a2-stage procedure. Of the 14 in whom resurfacing wasdone unilaterally, THA was done in 5 patients on thecontralateral side, either before or along with theresurfacing surgery. Three of these patients had beenplanned for bilateral resurfacing but underwent THA onone side due to intraoperative difficulties, whichincluded inability to dislocate the hip in 2 hips andlateral neck notching in 1. The average operating timewas 94 minutes, with a range of 76 to 122 minutes. Theaverage blood loss ranged from 300 to 700 mL, with amean of 400 mL. One patient who had superficialwound infection showed good response to a course ofantibiotics.

Table 2. Clinical Results

Mean Values

AnkylosingSpondylitis(n = 20)

RA(n = 9)

All Hips(n = 31)

Flexion-extension(deg.)

Preoperative 33.75 59.44 42.74Postoperative 109.75 118.33 112.74Improvement 76 58.89 70

Abduction-adduction(deg.)

Preoperative 13 27.78 18.7Postoperative 47.75 52.78 49.35Improvement 34.75 25 30.64

Rotation (internal +external) (deg.)

Preoperative 10.75 24.44 15.96Postoperative 47.25 47.78 47.25Improvement 36.5 23.34 31.29

Total ROM (deg.) Preoperative 57.5 111.67 77.41Postoperative 204.75 218.89 209.35Improvement 147.25 107.22 131.94

HHS Preoperative 36.4 45.56 39.6Postoperative 87.1 90.78 88.4HHSImprovement

50.7 45.22 48.77

HHS indicates Harris hip score.

Hip Resurfacing Arthroplasty in Inflammatory Arthritis � Malhotra et al 17

During the follow-up period, 1 of the patientssustained fracture of the femoral neck 14 months afterthe resurfacing procedure. The femoral component wasreplaced with a stemmed femoral component, whereasthe acetabular cup was retained (Fig. 1). Microscopicpathology showed features of generalized osteonecrosiswith no evidence of foreign body reaction to bone-cement at the bone-cement interface, suggesting thatthe osteonecrosis occurred after the resurfacing proce-dure [18]. The remaining 22 patients (31 hips) with aminimum follow-up of 3 years were further analyzed.The mean period of follow-up was 43 months, with arange of 36 to 56 months. The clinical results at finalfollow-up are depicted in Table 2. The mean preoper-ative Harris hip score was 39.6, with a range of 17 to 51.Postoperatively, the mean Harris hip score improved to88.4. The lowest score of 79 was seen in a patient withankylosing spondylitis and was graded as having a fairoutcome. The result was good in 17 hips and excellent in13 hips, when grading was done according to Harris hipscore. Patients with rheumatoid arthritis had significant-ly (P b .02) higher mean preoperative and postoperativescores (45.56 and 90.78, respectively) as compared withthose with ankylosing spondylitis (36.4 and 87.1,respectively). However, the improvement in Harris hipscore was greater in patients with ankylosing spondylitisas compared with those with rheumatoid arthritis

Fig. 1. Twenty-two-year-old man with ankylosing spondylitis wason the right side because of difficulty in dislocating the hip. Resurrevised to a conventional stemmed femoral component. Histoosteonecrosis with no evidence of remodeling changes at the bon

(P= .05). Ten patients expressed difficulty in reaching theshoes and requirement of assistance for the same. Nine ofthe 10 patients had involvement of the spine. Fourpatients had occasional hip pain, whereas 1 had mild hippain with no effect on average daily activities. There wassignificant increase in flexion-extension, abduction-adduction, and rotation (P = .000). The mean sum

planned for bilateral hip resurfacing. However, THA was donefacing failed after 14 months, and the femoral component waslogic evaluation of the remnant head showed evidence ofe-cement interface.

18 The Journal of Arthroplasty Vol. 27 No. 1 January 2012

ROM increased from 77.41° preoperatively to 209.35°postoperatively. The gain in total ROM was significantlygreater (P = .000) in those with ankylosing spondylitis(147.25°) as compared with that with rheumatoidarthritis (107.22°).Horizontal positioning of the acetabular component

was observed in 2 (6.4%) hips. Radiolucency around theacetabular component (zone II) was evident in 1 (3.2%)of 31 hips. The radiolucency was nonprogressive, andthe patient remained asymptomatic. Two hips hadexcessive valgus postioning of the femoral component.There was neither any case with radiolucency aroundthe femoral stem nor a case with migration orsubsidence of the femoral component. Heterotopicossification was found in only 2 (6.4%) of 31 hips,both in patients with ankylosing spondylitis. One hadBrooker grade I heterotopic ossification, whereas theother had grade II heterotopic ossification.

DiscussionAfter the improvements in surgical technique and

metallurgy, third-generation total hip resurfacing withmetal-on-metal articulation has been successfully intro-duced in younger patients with primary osteoarthritis ofthe hip with promising short- to medium-term results[14,19-21]. Success of the technique in primary osteo-arthritis has prompted experimentation of the viabilityof this unique design in patients with osteoarthritissecondary to osteonecrosis of the femoral head [22,23],developmental dysplasia of hip [24], Perthe disease, andslipped capital femoral epiphysis [25]. However, incertain conditions such as developmental dysplasia ofhip, results of resurfacing are largely discouraging [26].Li et al [6] reported 1 failure, secondary to periprostheticfracture in 39 resurfaced hips in patients with ankylosingspondylitis, with a follow-up of 22 months. Our studyrevealed a survivorship of 96.9%, for resurfacingarthroplasty in inflammatory arthritis, at a meanfollow-up of 43 months. We had used the ASR implantin all resurfacings done during the study period. Datafrom the Australian National Joint Replacement Registryhas revealed that the ASR implant has a higher revisionrate as compared with the Birmingham Hip Resurfacingsystem (2.6% vs 0.3% per 100 observed componentyears) [26]. Hence, presently, we are using theBirmingham Hip Resurfacing for this indication.Fracture of the femoral neck is one of the most

common causes of failure of resurfacing [26]. The onlyfailure among 32 hips (3.1%) in the current study wassecondary to fracture of the femoral neck, probably dueto osteonecrosis of the remnant head. Campbell et al[27] observed that femoral neck fractures after resurfa-cing show a bimodal distribution. In their cohort, most ofthe femoral neck fractures occurred within 6 months ofresurfacing, and there was a second peak at around 12months. Our cohort has a minimum 3-year follow-up. It

is therefore rational to imply that more failures due tofracture of the femoral neck are unlikely to develop inour cohort as the critical time period has elapsed.Femoral failures can be treated by femoral-only revi-sions with blood loss and operating times similar toprimary THA. However, femoral-only revision of failedresurfacing to THA may result in a second phase of run-in wear when the retained acetabular componentarticulates with the new femoral head [28,29]. Femo-ral-only revisions have also been found to be inferior toprimary THA in terms of survivorship [30]. Osteoporo-sis, either due to disease or steroid induced, couldpredispose to femoral neck fracture. The associationbetween vitamin D deficiency and rheumatologicdisorders is well documented [7-10]. The prevalence ofvitamin D deficiency has been found to be as high as78% among healthy adults from our population, using acutoff of 50 nmol/L [11]. In light of the above facts, thehigh-prevalence vitamin D deficiency in our cohort wasnot unexpected. Careful patient selection with particularattention to proximal femoral osteopenia and abnormalvitamin D levels and institution of appropriate pharma-cological measures to correct the same, we believe, areprudent measures to prevent periprosthetic fractures inpatients with inflammatory arthritis. In addition, theimportance of accurate positioning of implants inpreventing this complication cannot be overemphasized.Our records revealed that 2 hips planned for resurfa-

cing underwent THA due to difficulty in dislocating thehead. Anticipation of such difficulties and readiness toswitch the plan intraoperatively to conventional hiparthroplasty is essential.The age distribution of our cohort suggests that these

patients are likely to lead active lives and outlive aprimary hip arthroplasty. Preservation of proximalfemoral bone stock and bone mineral density [1] withhip resurfacing would be particularly beneficial to thesepatients.The improvement in the Harris hip score was marked.

Twenty-six of the 31 hips were completely pain free, 4had only slight and occasional pain, 1 had mild pain, andnone of the patients required a restriction of routineactivities. Excellent or good outcome was achieved in 30of 31 hips, and a fair outcome was achieved in 1 hip. Thefinal score achieved was lower than that reported withresurfacing in cohorts comprising predominantly casesof primary osteoarthritis [14,21,29,30]. The scores were,however, nearly equal to or better than scores recordedafter THA for ankylosing spondylitis [31,32].Resurfacing arthroplasty has been found to provide

equal or better ROM as compared with conventionalTHA [5,6,33]. The increased ROM provided by large-diameter articulations would be particularly beneficial inpatients with stiff spines. Preoperative ankylosis andsubsequent weakening of muscles, fear of dislocationwith small diameter femoral heads, and subsequent

Hip Resurfacing Arthroplasty in Inflammatory Arthritis � Malhotra et al 19

protected postoperative mobilization of the hip havebeen postulated as causes of inferior ROM after hiparthroplasty for inflammatory arthritis [6]. The excellentpostoperative ROM achieved in our cohort may be inpart due to the early and confident mobilization that thelarge-diameter articulation allowed. The study byGarbuz et al [34] suggests that resurfacing would retainthe benefit of a large-diameter articulation and be lesshazardous with respect to the release of metal ions ascompared with large-diameter metal-on-metal THA.Patients with ankylosing spondylitis had a lowerpostoperative ROM as compared with their counterpartswith rheumatoid arthritis (204.75° vs 218.89°). Howev-er, the ROM achieved was higher than that reported inpatients with ankylosing spondylitis who underwentconventional THA [35,36].Heterotopic ossification has been a source of concern

after hip resurfacing [37]. However, we found evidenceof heterotopic ossification in only 2 hips (6.4 %), andboth were low grade. Meticulous surgical technique andthe use of indomethacin prophylaxis were essentialfeatures of our protocol to minimize this complication.The short follow-up and the absence of control groups

limit the conclusions that can be drawn from the study.Nevertheless, the study reveals promising results for hipresurfacing in patients with inflammatory arthritisbelonging to the young adult population, the agegroup for which hip resurfacing is ideally suited andfor whom it offers the greatest benefit. The enhancedROM provided by the large-diameter metal-on-metalarticulation is particularly useful for those with poly-articular involvement and stiff spines.

AcknowledgementWe are grateful to Director-Professor Dr. Virendra N.

Sehgal, MD, FNASC, FAMS, FRAS (Lond), who reviewedand meticulously edited this article.

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