Faculty Bibliography

Hip resurfacing devices require a new radiographic evaluation technique owing to femoral components with short or no stems. Fourteen US surgeons implanted 1148 metal-on-metal hip resurfacing (HR) devices in a US-FDA-IDE clinical trial, which began in 2001. In this multi-center, prospective study, 337 patients (mean age, 50.1 years) were enrolled as a study group of unilateral HR arthroplasties. Radiographs of 292 HR arthroplasties at a minimum 2-year follow-up (maximum 3 years) were reviewed. There were 10 patients with radiographic evidence of femoral component instability beyond 2 years, as evidenced by subsidence > or = 5mm. Of these, 7 did not have clinical symptoms associated with femoral component instability. In the study group, 24 revisions were reported, of which 8 were due to femoral neck fractures, 4 were due to acetabular component loosening, 11 were due to femoral component loosening, and 1 due to dislocation

No consensus exists for the optimal surface finish on cemented total hip prosthesis stems. The purpose of this study was to determine the effects of stem finish and interfacial cement porosity on the integrity of the stem-cement interface. Simulated stems made of Co-Cr, having polished or matte surfaces, at room temperature or heated to 37 degrees C, were cemented into Sawbones simulated femurs. Push out testing of the stem-cement interface was performed immediately after cement polymerization and after two aging periods in 37 degrees C saline or 37 degrees C air, and the extent of interfacial porosity at the stem-cement interface was determined. Polished stems exhibited an average 60% greater interfacial strength than that of matte stems initially and up to 240% after aging treatments. Cement porosity at the stem-cement interface and incomplete cement interdigitation into surface asperities on matte stems likely allowed saline penetration into the stem-cement interface during wet aging, resulting in a rapid decrease of shear strength. Stem preheating to 37 degrees C virtually eliminated interfacial pores and resulted in greater shear strengths regardless of surface finish. Polished stem surfaces with stem preheating provided the best interfacial shear strength and sealing ability against saline penetration into the stem-cement interface and could result in increased longevity of stem fixation

The kinematics of 10 total knee replacements with poor flexion (<90 degrees ) were compared with 11 replacements with good flexion (>110 degrees ) at a mean of 3 years from surgery using optical calibration with implant shape-matching techniques from radiographs taken in standing, early-lunge, and late-lunge positions. There were no significant differences between groups in anteroposterior translation of the medial and lateral femoral condyles or tibial rotation during standing and early lunge. Groups differed in amount of posterior translation of the femoral condyles during late lunge because of the poor-flexion group's inability to achieve the same amount of flexion as the good-flexion group. Poor flexion after total knee arthroplasty, we conclude, is not associated with abnormal kinematics in the setting of well-aligned, well-fixed implants

A retrospective study of 132 patients (63 spinal anesthesia and 69 general anesthesia) undergoing total hip arthroplasty was performed by 4 fellowship-trained adult reconstructive surgeons to determine the influence of anesthesia type on postoperative limb length and medial offset. Limb length discrepancy occurred in 87.0% of patients who received regional anesthesia as opposed to 47.6% patients who had general anesthesia (P<.001). Differences in postoperative medial offset measurements between the 2 groups were not statistically significant. It was concluded that surgeons operating on patients who receive regional anesthesia should supplement intraoperative tests for assessing hip stability with meticulous preoperative templating to avoid overlengthening the operative limb

Psoriatic arthritis is an inflammatory arthropathy as- sociated with the characteristic dermatologic lesions of psoriasis. The diagnosis of psoriatic arthritis is quite difficult, due to the overlap of patients with osteoarthritis (OA) or rheumatoid arthritis (RA) with concomitant non-associated psoriasis. A nonspecific elevation in inflammatory markers (erythrocyte sedimentation rate, ESR; antinuclear antibodies, ANA; or rheumatoid factor, RF) and characteristic radiographic features are often present in these patients. The mainstay of treatment is medical management, using NSAIDs, various immunosuppressants, and anti-TNF agents, for both pain control and possibly as disease modifying agents. Only a minority of patients require surgical intervention, leading to the limited amount of literature concerning total joint arthroplasty and psoriatic arthritis. While past literature has yielded high infection rates post-arthroplasty, newer studies have found more promising results. Alternative surgical options for treating destructive arthritis include open or arthroscopic synovectomy. While early results are promising, recurrence rates and long-term outcomes are not yet available

Wear debris from metal-on-polyethylene articulation in conventional total hip arthroplasty can limit the implant's longevity. Modern ceramic material with high wear resistance and low fracture risk has the potential to extend the lifetime of total hip arthroplasty, which makes the procedure potentially more suitable for young, active patients. Concerns with brittle ceramic material include fracture risk, the 'squeak' phenomenon, and potentially a higher dislocation rate secondary to limited neck lengths and liner options. We therefore determined the early dislocation rate in modern ceramic-on-ceramic total hip arthroplasty. In 1635 total hip arthroplasties performed over the 9-year period (1996-2005), we observed three anterior and 15 posterior dislocations (1.1%). All were treated successfully, one with a revision and 17 with closed reduction under general anesthesia. Ceramic-on-ceramic total hip arthroplasty can be a good alternative bearing surface with a low dislocation rate

Currently, there are several femoral stem designs available for use, but few have an extended track record. We have previously reported on 10- and 15-year outcome studies of total hip arthroplasty (THA) using a cemented normalized and proportionalized femoral stem from a single surgeon series. This is a follow-up study reporting the minimum 20-year outcome of this femoral stem design. The study began with THA performed in a consecutive series of 184 patients; stem fixation was achieved using first-generation cementing techniques. The overall early complication rate was 10%. There were 23 patients (31 hips) who had been followed-up for a minimum 20-year period (average 21.3 years). Mean d'Aubigne and Postel scores improved from 5.9 to 11.3; mean Harris hip scores improved from 43.8 to 92.8. Kaplan-Meier survivorship was 93% at 20 years (95% confidence interval); there were no stem failures. The use of a cemented normalized and proportionalized femoral stem in primary THA provides satisfactory long-term clinical and radiological outcomes in patients.

Rehabilitation after total hip and knee arthroplasty is a rapidly expanding discipline. With the introduction of minimally invasive techniques and the pressure of insurance regulations, postoperative rehabilitation has been placed on an accelerated track. As surgeons turn to more aggressive postoperative protocols and early entry into outpatient therapies, we introduce a pre- and postoperative program involving the Pilates method. Renewed patient interest in the use of Pilates for postoperative rehabilitation has led to the development of safe and modified exercises for patients undergoing total hip or knee arthroplasty. While this technique appears safe and effective anecdotally, further controlled trials are necessary to prove its validity

The expandable nail concept uses high-pressure saline to inflate the diameter of a cylindrical implant to achieve fixation within the medullary canal of bone. Expandable nails are used clinically in a number of fracture management applications and have been more recently developed as a femoral component for total hip replacement. In this study, the expandable total hip replacement stem design was evaluated, specifically testing to determine if acrylic cement can be used in place of saline for permanent expansion, to observe the amount of stem subsidence after cyclic loading, and to document if stem expansion creates untoward stresses in the femur. The results included that the expandable femoral component could be expanded with cement if careful control of cement viscosity is used with a modified filling technique. Neither untoward hoop strains nor stem subsidence was found in tests with the cadaveric femurs. Bench testing has confirmed the stability of these stems. In addition, the substitution of cement for saline would make the construct permanent, avoiding the risk of deflation and loosening. The concept of an expandable femoral prosthesis is appealing and would have many potential clinical applications. The need for cemented stems or the more difficult and costly 'Ling technique' could be avoided with their use in tumor surgery, hip fracture management, and total hip replacements associated with osteoporosis or a patulous femora in both primary and revision settings