Medialization of the Patella in Total Knee Arthroplasty

Kris Lewonowski, M.D., Wichita, Kansas, Lawrence D. Dorr, M.D., Edward J. McPherson, M.D., Glen Huber, and Zhinian Wan, M.D., Los Angeles, California

The Journal of Arthroplasty, Volume 12, Number 2, 1997, pp 161-167

Abstract: Patellar complications of total knee arthroplasty remain the most common cause of pain and reoperation. Laboratory studies have suggested that medialization of the patella will improve tracking of the patella on the trochlea of the femoral component. The purpose of this study was to determine if clinical medialization of the patellar component on the patellar bone would improve tracking of the patella as demonstrated radiographically. Sixty-two knees were randomized so that 31 knees had a centrally placed patellar component and 31 had the patellar component placed on the medial two thirds of patellar bone. There was no difference between the two groups with respect to either clinical or radiographic results in the first year after surgery. There was no improvement compared with previous reports in the incidence of tilt and displacement. The one improvement was a reduction in the incidence of lateral release. Thus, consequences of lateral release such as postoperative morbidity, avascular necrosis of the patella, and stress fracture of the patella can be avoided. It is recommended that the patellar component be placed on the medial two thirds of the patella to reduce the occurence of lateral release. Tracking of the patella during surgery can be assessed using a single suture placed at the superior pole of the patella and this technique in combination with the no-thumbs test provides an additional means of evaluation for patellar tracking.

Patellar Component Medialization in Total Knee Arthroplasty

Aaron A. Hofmann, M.D., Thomas K. Tkach, M.D., Christopher J. Evanich, M.D., Marcelo P. Camargo, M.D., and Yongde Zhang, M.D., Salt Lake City, Utah

The Journal of Arthroplasty, Volume 12, Number 2, 1997, pp 155-160

Abstract: 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 (i.e., 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.