Posterior stabilization in total knee arthroplasty with use of an ultracongruent polyethylene insert.

Fifty-three primary and 47 revision posterior cruciate ligament (PCL)-substituting total knee arthroplasties (TKAs) using a highly conforming (ultracongruent) polyethylene insert were retrospectively reviewed over a 48- to 106-month (mean, 60+/-11 months) follow-up period. These 100 knees were age and sex matched with another 100 TKAs performed using a PCL-sparing design. The ultracongruent design has an anterior buildup of 12.5 mm and a more conforming articular surface to match better the radius of the femoral component. In primary and revision TKAs, the average Hospital for Special Surgery knee score (P = .3) and range of motion (P = .43) were similar between the PCL-sparing and ultracongruent groups. In primary and revision TKAs, there were no revisions resulting from instability for patients receiving an ultracongruent insert versus 5 knees in the PCL-sparing control group secondary to subsequent postoperative anteroposterior instability and PCL insufficiency.

6- to 10-year experience using countersunk metal-backed patellas.

Three hundred two consecutive cementless total knee arthroplasties (Natural Knee, Intermedics Orthopedics, Inc., Austin, TX) were performed using a metal-backed, porous-coated patellar component. Fifty-nine patients died and 31 were lost to follow-up evaluation, resulting in 212 knees available for evaluation at 6 to 10 years. The mean follow-up period was 91 months. The mean modified Hospital for Special Surgery total knee score improved from 58 before surgery to 98 at the most recent follow-up visit. Mean patellar translation and tilt were 2.75 mm and 3.5 degrees, respectively. There were no patellar lucencies nor loosening. Eleven patients (5%) underwent revision of the patellar component. Overall patellar survivorship was 96%. Comparatively good results can be achieved with the use of a metal-backed patellar component if component design, surgical technique, and patellar alignment are properly addressed.

Patellar component medialization in total knee arthroplasty.

Intraoperative correction of patellar maltracking has traditionally involved the use of a lateral retinacular release. Problems, however, related to lateral retinacular release include increased postoperative pain and wound healing complications, compromised patellar blood flow, and longer rehabilitation. The purpose of this study was to assess the effect of patellar medialization in total knee arthroplasty. One hundred forty patients underwent total knee arthroplasty using the same components. Two groups of 70 patients each made up the study. Group 1 included patients whose patellar components were centralized on the patella, and group 2 consisted of patients in whom the patellar component was medialized to reproduce the patient's anatomic high point (ie, sagittal ridge). Lateral retinacular release was required in 45.5% of the patients in group 1 compared with 17% in group 2. The technique of patellar medialization is described.

Treatment of infected total knee arthroplasty using an articulating spacer.

Twenty-six patients with late infected total knee arthroplasties were treated by debridement and removal of components and all cement, preserving collateral ligaments. At time of debridement, an articulating spacer was fashioned to allow partial weightbearing and knee range of motion (ROM) during rehabilitation. This spacer was implanted using antibiotic-impregnated bone cement. For this purpose, 4.8 g of powdered tobramycin was mixed with each 40-g batch of Simplex cement. Cement was applied early to the components, but applied late to the femur, tibia, and patella to allow molding to the defects and bone without adherence to bone. Patients received tailored intravenous antibiotic therapy for 6 weeks in addition to this antibiotic-impregnated cement for treatment of a variety of gram positive and gram negative organisms. All patients had cemented revision total knee arthroplasty using antibiotic-impregnated cement with standard cementing techniques used. All patients but 1 had reimplantation; this patient died of unrelated causes before revision. Range of motion before revision was 10 degrees to 95 degrees. Followup averaged 30 months (range, 13-70 months). The average Modified Hospital for Special Surgery Knee Score after revision was 87 points (range, 53-100 points), with 92% good to excellent results. Range of motion after reimplantation was 5 degrees to 106 degrees. There have been no recurrences of infection. Use of an articulating spacer to treat infected total knee arthroplasty improves ultimate ROM and soft tissue health and significantly decreases the risk of reinfection.