Faculty Bibliography

Parkin mutations account for the majority of familial and sporadic early onset Parkinson's disease (EOPD) cases with a known genetic association. More than 100 mutations have been described in the Parkin gene that includes homozygous, compound heterozygous, and single heterozygous mutations. We have designed a Parkin mutation genotyping array (gene chip) that includes published Parkin sequence variants and allows their simultaneous detection. The chip was validated by screening 85 PD cases and 47 controls previously tested for Parkin mutations. Similar genotyping microarrays have been developed for other genetically heterogeneous diseases including age-related macular degeneration. Here, we show the utility of a genotyping array for Parkinson's disease by analysis of 60 subjects from the Genetic Epidemiology of Parkinson Disease (GEPD) study that includes 15 early-onset PD case probands and 45 relatives.

This study determined the accuracy of plain radiography in detecting osteolytic lesions around total knee prostheses compared to multi-detector computed tomography (CT). Thirty-one patients diagnosed with periprosthetic osteolysis by multi-detector CT after total knee arthroplasty (TKA) were studied. Computed tomography for each patient was retrospectively reviewed in a blinded fashion. The plain radiographs for each patient that had been obtained prior to CT were reviewed in the same manner. The results of the CT were compared with the results of the radiographs. The number, size, and location of the lesions were compared. The multi-detector CT detected 48 lesions in 31 knees: 40 tibial lesions, 4 femoral lesions, and 4 patellar lesions. Radiographic diagnosis was made in 6 of the 40 tibial lesions, 2 of the 4 femoral lesions, and 0 of the 4 patellar lesions. Plain radiographs are inadequate for evaluating periprosthetic osteolysis in TKA with only 8 (17%) of 48 lesions detected by multi-detector CT visible on the standard radiographs. Multi-detector CT provides the surgeon with a diagnostic and preoperative planning tool when osteolysis is suspected.

Although it is well known that patients with preoperative hemoglobin levels <13.0 g/dL are at a higher risk for requiring postoperative transfusions, the ideal blood management strategy for this group of patients remains unclear. This study compared preoperative autologous donation with preoperative administration of epoetin alfa as a method to maximize perioperative hemoglobin levels and minimize blood transfusions in these high-risk patients undergoing total knee arthroplasty (TKA). Results show that both preoperative autologous donation and epoetin alfa were successful in decreasing the need for allogeneic blood transfusions following TKA in high-risk patients. Epoetin alfa was more effective in maximizing perioperative hemoglobin levels.

Two hundred seventy-nine primary total knee arthroplasties were performed with a modular, cemented, third-generation, posterior-stabilized prosthesis. At mean follow-up of 48 months (range, 24-72 months), the outcomes of 238 knees (85%) were evaluated with the Knee Society's Knee and Functional Scoring Systems and Roentgenographic Scoring System. The mean preoperative Knee Society Knee Score was 48 points compared with 96 points at latest follow-up. There were no cases of patellar clunk, symptomatic patellar maltracking, or posterior dislocation. There was no radiographic evidence of loosening or osteolysis, and no revisions were performed or recommended for loosening, osteolysis, instability, or polyethylene wear. Three patients developed late infections. These early results support the ongoing use of this design; however, long-term studies will be required.

Numerous methods for creating symmetric flexion and extension gaps during knee arthroplasty in valgus knees have been proposed, and no consensus exists about the optimal technique. The "pie crust" technique for lateral soft tissue releases has been used extensively, yet few clinical results have been published. In this study, the clinical outcomes of 24 consecutive knees in 24 patients in whom this method was used in conjunction with a cemented posterior-stabilized prosthesis were evaluated. At a mean of 54 months' (range 24-69 months) follow-up, the knees were performing well with a mean Knee Society score of 97 (range 87-100) and mean range of motion of 121 degrees (range 100 degrees -145 degrees). Importantly, there were no clinical failures or cases of postoperative instability and no cases of radiographic loosening or wear.

There is a lack of consensus with regard to ways to minimize blood transfusions after total knee arthroplasty. We surveyed 434 members of the American Association of Hip and Knee Surgeons, each of whom averaged 18 years in practice and performed an average of between 100 and 150 knee replacements a year, about their preferences and practices regarding blood conservation during total knee arthroplasty. Of those surveyed, only 24% reported that there was a blood conservation program in place at their institutions. Fifty-nine percent of those surveyed routinely asked their patients to donate blood before unilateral and bilateral knee replacements. The amount of blood collected averaged 1.32 units (range, 1-4 units) and 2.04 units (range, 1-4 units) before unilateral and bilateral knee arthroplasty, respectively. Nearly half (47.5%) reported they rarely ever prescribed epoetin alfa because of a combination of cost, time, and labor issues. Furthermore, the majority (84%) has not had any experience with the use of antifibrinolytics. Overall, the mean transfusion rate after unilateral knee replacement was estimated to be less than 5% (range, 0%-20%) whereas the rate after bilateral knee replacement was estimated to be between 10% and 20% (range, 5%-20%).

From 1994 to 1998, we performed 170 bilateral total knee arthroplasties (TKAs) with cemented, posterior cruciate-substituting prostheses. Blood management included preoperative autologous donation, symptom-based transfusion, and autoreinfusion devices. Perioperative allogeneic transfusion rates for patients who donated 0, 1, 2, 3, or 4 units of blood were 40.00%, 0.00%, 3.70%, 0.00%, and 3.23%, respectively. Preoperative autologous donation >2 units also resulted in lower preoperative hemoglobin levels. For bilateral TKA, a protocol of 2 preoperative autologous donation units and reinfusion of postoperative drainage reduces anemia during the preoperative and postoperative periods.

This prospective study quantified the weight change in 20 consecutive patients undergoing total knee arthroplasty. Resected bone, soft tissues, and bone reamings were collected during surgery and weighed using a digital scale at the end of the procedure. Results were compared to the cumulative weights of the prosthesis, bone cement, patellar component, and polyethylene liner. Average weight of the resected bone and soft tissues was 167.71 g for men and 130.13 g for women. Mean weight of the implanted prosthesis and cement used was 509.92 g for men and 422.56 g for women. Men tended to receive a larger-sized prosthesis than women. Overall, the average weight gain as a result of knee arthroplasty was 345.54 g for men and 292.44 g for women. This translates to an insignificant increase in body weight.

In designing a posterior-stabilized total knee arthroplasty (TKA) it is preferable that when the cam engages the tibial spine the contact point of the cam move down the tibial spine. This provides greater stability in flexion by creating a greater jump distance and reduces the stress on the tibial spine. In order to eliminate edge loading of the femoral component on the posterior tibial articular surface, the posterior femoral condyles need to be extended. This provides an ideal femoral contact with the tibial articular surface during high flexion angles. To reduce extensor mechanism impingement in deep flexion, the anterior margin of the tibial articular component should be recessed. This provides clearance for the patella and patella tendon. An in vivo kinematic analysis that determined three dimensional motions of the femorotibial joint was performed during a deep knee bend using fluoroscopy for 20 subjects having a TKA designed for deep flexion. The average weight-bearing range-of-motion was 125 degrees . On average, TKA subjects experienced 4.9 degrees of normal axial rotation and all subjects experienced at least -4.4 mm of posterior femoral rollback. It is assumed that femorotibial kinematics can play a major role in patellofemoral kinematics. In this study, subjects implanted with a high-flexion TKA design experienced kinematic patterns that were similar to the normal knee. It can be hypothesized that forces acting on the patella were not substantially increased for TKA subjects compared with the normal subjects.