Results: Of these 445 patients, 5.8% (26/445) of knees were revised, and 8% (36/445) of knees requireda nonrevision reoperation. The overall rate of having at least 1 reoperation in this group of patients was12.6% (56/445).We then divided all of these patients into subgroups to determine if the revision ratedecreased as the institutional and surgeon experience increased. In considering only revisions andreoperations performed within the first 2 years postoperative, the first 253 patients had a revision rate of3.8% (9/235) and a reoperation rate of 6.8% (16/235), and the second 254 patients had a revision rate of3.8% (8/210) and a reoperation rate of 6.7% (14/210).

Discussion: The overall rate of revision (5.8%), and reoperation (8%) has remained consistent with ourprevious report. We expected to find, as other authors have reported, as our experience increased and welearned the intricacies of this procedure and implant, that our complication rate would decrease. However,with the numbers available, we were unable to show any statistically significant improvement in theserates. Although we remain advocates of UKA, we explain this complication rate to our patients to aid in thesurgical decision-making process.

doi:10.1016/j.arth.2008.01.266

POSTER #207

METAL-ON-METAL HIP RESURFACING: APPROPRIATE PATIENT SELECTIONIS ESSENTIALD.Gordon Allan,MD*, Joseph C.Milbrandt, PhD,KathyK. Trier, PhD*, Marybeth Naughton, BS*

Metal-on-metal hip resurfacing is a useful option to consider for increasingly younger and more activepatients. We report here patient selection factors associated with increased risk of revision afterimplantation of 1148 Cormet 2000 resurfacing implants. This prospective, multicenter study evaluatedsubjects preoperatively through 2 years using standardized questionnaires, physical examinations, andradiographic evaluations. Eight hundred twenty-five men and 323 women received the device. Forty-four(3.8%) revisions were required; 21 in women (6.5%) and 23(2.8%) in men. Fifty percent of the revisionsoccurred in patients with smaller component sizes, and 20%, in patients with a diagnosis other than OA.This study identified 4 factors predictive of revision.

These included small component size (correlated with female sex), diagnosis other than OA, preoperativeleg length discrepancy greater than 1 cm and preoperative Harris Hip Score below 42 points. There was asignificant additive effect of these risk factors. Appropriate selection of patients with fewer risk factorsshould yield better outcomes in this population.

The FDA has not cleared the medical devices(s) (Cormet 2000, Corin) for the use described in this presentation.

doi:10.1016/j.arth.2008.01.267

POSTER #208

DIFFERENCES IN DEMOGRAPHICS, SOCIAL HISTORY, RESOURCE USE, ANDHEALTH STATUS BY INSURANCE PAYER GROUP IN AN ORTHOPEDICSURGICAL PRACTICEAmanda Smith, Nalini Govindarajan, Kevin J. Bozic, MD*

Introduction: Numerous studies have shown that Medicaid patients have less access to medical care,but few studies have focused on the consequences of reduced access by the poor to much-neededspecialty care. The purpose of this study was to determine if Medicaid patients presenting to anorthopedic surgical practice differed from other patients with respect to baseline demographiccharacteristics, social history, resource use, and health status.

Methods: This is a prospective study of 138 consecutive new patients who were scheduled for theirinitial examination at an orthopedic surgery specialty clinic between June 1, 2006, and August 31, 2006.Baseline demographic information, social history, resource use, and clinical outcomes (Harris Hip Scoreor Knee Society Index) were compared between Medicaid, Medicare, and commercial payer patients. Inaddition, the distance patients lived from the clinic was measured.

Results: Medicaid patients were significantly more likely to be on disability unrelated to their hip orknee problem (P b .001), single (P b .05), and less educated (P b .05) than their Medicare or commercialpayer counterparts. In addition, Medicaid patients were more likely to have a current or past history ofillegal substance use than Medicare and commercial payer patients (P b .05). There were no statisticallysignificant differences in history of psychiatric illness, use of heavy narcotics, use of tobacco, or abuse ofalcohol. After adjusting for age, we found a significant difference in baseline function between insurancegroups (P b .0001). Compared with other payer groups, Medicaid patients had to travel twice as far toreceive treatment (median of 39.3 vs 18.7 miles) and were twice as likely to be late to appointments,cancel appointments within 24 hours of scheduled time, or be no-shows.

Conclusions: Medicaid patients presenting to an orthopedic practice present with important demographicdifferences and significantly lower functional scores than their Medicare and commercial payer counterparts.Decreased access to health care and increased time topresentationmay account for the difference in functionalscores seen at the time of presentation. Despite having advanced arthritis of the hip and knee that could benefitfrom hip or knee arthroplasty, sociodemographic differences such as lower education level, lack of currentemployment, less social support, and higher illegal substance use rates all may contribute to providerschoosing not to recommend these elective orthopedic procedures to this challenging group of patients.

doi:10.1016/j.arth.2008.01.268

POSTER #209

CEMENTLESS ACETABULAR RECONSTRUCTION IN REVISION TOTAL HIPARTHROPLASTY: EVALUATION AT A MINIMUM OF 20 YEARSDaniel Park, Craig J. Della Valle, MD*, Laura Quigley*, Richard Berger, MD*, AaronRosenberg, MD*, Jorge O. Galante, MD*

Introduction: Prior studies of revision total hip arthroplasty (THA) have determined that cementlessacetabular reconstruction performs well in the setting of revision THA; however, the long-term resultsare unknown. The goal of this study was to determine the clinical and radiological outcomes ofrevision THA with a cementless acetabular component at minimum 20-year follow-up.

Method: One hundred thirty-eight consecutive revision THAs in 131 patients with a mean age of 55years were performed with a hemispherical, porous-coated acetabular component inserted with screws(HG-1, Zimmer). At the most recent evaluation, 53 patients had died (55 hips), and 6 patients were lostto follow-up (6 hips), leaving 77 hips in 72 patients available for follow-up at a minimum of 20 years(range, 240-284 months).

Results: The mean Harris Hip Score of surviving patients without requiring repeat acetabular revisionimproved from 52.0 preoperatively to 79.1 (P b .05). Repeat acetabular revision was required in 21hips (15.2%); 20 of the acetabular components were well fixed, including 7 removed for infection(5.1%), 7 for recurrent instability (5.1%), and 6 incidental removals at the time of femoral revisionsurgery (4.3%). One component was found to be loose at the time of femoral revision and removed.Five patients required a modular liner exchange for wear or osteolysis. Two cups wereradiographically loose.

Conclusion: Revision THA with a cementless acetabular component provides excellent fixation at 20years; however, with continued follow-up, reoperations for wear and osteolysis, which were previouslynot seen in this cohort, increase.

doi:10.1016/j.arth.2008.01.269

POSTER #210

DEFINING THE ETIOLOGIES OF PREMATURE HIP JOINT DEGENERATION: DOIMPINGEMENT DISORDERS HAVE A ROLE?John Clohisy, MD*, Jason Robison, John Callaghan, MD*, Lucian Warth, BS, MichaelDobson, Steve Liu

Introduction: Improved understanding of the pathomechanics associated with hip osteoarthritis hasheightened interest in joint preservation surgery. Nevertheless, the specific disease patterns associatedwith hip degeneration are not completely understood. The purpose of this study was to define theetiologies of premature hip joint deterioration and to characterize the structural abnormalities associatedwith secondary osteoarthritis.

Methods: We reviewed 730 hips treated with primary total hip arthroplasty in patients younger than 50years. Clinical and radiographic records were examined to define the etiology of disease and tocharacterize structural anatomy.

Results: Of 730 hips, 54% were in men, and 46%, in women. Average age was 40.2 years. Twohundred twenty (30.1%) had osteonecrosis; 48 (6.6%), posttraumatic disease; 37 (5.1%),inflammatory arthritis; 405 (55.5%), osteoarthritis; and 20 (2.7%), inadequate radiographs. Of the405 osteoarthritic hips, 181 had DDH; 32, Perthes; 21, SCFE; 6, postsepsis; and 165, osteoarthritisof unknown etiology. An indepth radiographic analysis was then performed on these 165 hips: 78had radiographic findings consistent with cam impingement (reduced head-neck offset, asphericalfemoral head), 10 with pincer impingement (retroversion or coxa profunda/protrusio), and 40 withcombined cam/pincer impingement. Thirty-seven had no obvious structural abnormality, or diseasewas too advanced for interpretation.

Discussion: This study indicates that secondary osteoarthritis and osteonecrosis are themajor mechanismsof premature hip joint degeneration. For osteoarthritis cases with an unknown etiology, these data indicatethat hip impingement disorders are the most common cause of secondary osteoarthritis.

doi:10.1016/j.arth.2008.01.270

POSTER #211

TOTAL KNEE ARTHROPLASTY IN PARKINSON'S DISEASE: A PROTOCOL FORIMPROVED EXTENSIONDavid Nazarian, MD*, Robert E. Booth Jr, MD*

Introduction: There are few reports regarding total knee arthroplasty in patients with Parkinson'sDisease. This study is a review of a consecutive series of patients with the diagnosis of Parkinson'sDisease who underwent primary total knee arthroplasty.

Methods: Fifty-six knees were treated in patients with a prior diagnosis of Parkinson's disease whounderwent primary knee arthroplasty with a cemented posterior stabilized component and an allpolyethylene patellar component. Bone cuts were made such that the extension gap was purposely made2 mm larger than the flexion gap. A soft tissue tensor device and extramedullary alignment guide wasused, a thorough posterior release was performed, and Botox injections in the hamstrings postoperativelywere given. Patients were treated with extension slings at night and were evaluated clinically andradiographically using a modified Knee Society rating system.

Results: All patients had severe pain and disability before their index procedure. The average KneeSociety Score went from 49 to 86, whereas the functional score improved from 44 to 80, with anaverage follow-up of 4.9 years (range, 2-10). All patients had good or excellent pain relief andimprovement in their functional ability. Nine patients had a flexion contracture greater than 5°. Theaverage range of motion was 4 to 110°. Seven patients required manipulation under anesthesia. Four ofthese were treated with manipulation and casting. There were 4 cases of nonprogressive radiolucenciesand no cases of loosening.

Discussion and Conclusion: Total knee arthroplasty in patients with Parkinson's disease has beenfraught with complications, including flexion contractures with decremental functional results. Thisstudy reports on a consecutive series of patients who achieved very good functional results through apredetermined intraoperative protocol and an aggressive postoperative physical therapy regimen

AAHKS Abstracts � 325