TOTAL KNEE ARTHROPLASTY IN THE VALGUS KNEE

Abstract

We analysed the clinical and radiographic results after total knee arthroplasty in the valgus knee. Thirty six knees in 27 patients with a valgus alignment of more than 10 degrees of femorotibial angle underwent TKA. The average followup period was 7 years(range 1 to 14 years). Eighteen knees were implanted with a cruciate retaining prosthesis, 17 knees with a posterior stabilized prosthesis, and one knee with a constrained condylar prosthesis. In knees with a preoperative 15 degrees or greater femorotibial angle, the posterior stabilized prosthesis were necessary in 85%.

Medial parapatellar approach was used in 27 knees with a preoperative valgus 20 degrees or lesser femorotibial angle. With 20 to 29 degrees valgus, medial parapatellar approach was used in 5 knees and lateral parapatellar approach in 2 knees. With 30 degrees or greater valgus, lateral parapatellar approach was used in 2 knees.

The mean postoperative Hospital for Special Surgery knee scores were 89.5 points. Postoperative range of motion averaged 114.4 degrees. Postoperative alignment averaged 6.5 degree valgus. Radiolucent line or loosening was not seen in any knee. There were two deep infections in patients whose preoperative femorotibial angle was greater than valgus 20 degrees using lateral parapatellar approach.

Clinical and functional results after TKA in the valgus knee were similar to those in varus knee. But, prevention of deep infection in patients with marked valgus angle was important, especially using lateral parapatellar approach. A more constrained prosthesis was frequently used in more significant valgus deformity. In patients with severe valgus deformity needing lateral capsular release frequently, lateral parapatellar capsular approach was more reasonable than medial parapatellar approach to avoid medial and lateral capsular release simultaneously.