J Korean Orthop Assoc.  2021 Jun;56(3):253-260. 10.4055/jkoa.2021.56.3.253.

Review of the Reasons in Cases Requiring Varus/Valgus Constrained Prosthesis in Primary Total Knee Arthroplasty

• Kong DY
• Park SH
• Choi CH

• KMID: 2516657
• DOI: http://doi.org/10.4055/jkoa.2021.56.3.253

Abstract

Purpose
The least constrained prosthesis is generally recommended in primary total knee arthroplasty (TKA). Nevertheless, a varus/valgus constrained (VVC) prosthesis should be implanted when a semi-constrained prosthesis is not good for adequate stability, especially in the coronal plane. In domestic situations, however, the VVC prosthesis could not always be prepared for every primary TKA case. Therefore, it is sometimes impractical to use a VVC prosthesis for unsual unstable situations. This study provides information for preparing VVC prostheses in the preoperative planning of primary TKA through an analysis of primary VVC TKA cases.
Materials and Methods
This study reviewed 1,797 primary TKAs, performed between May 2003 and February 2016. The reasons for requiring VVC prosthesis and the preoperative conditions in 29 TKAs that underwent primary TKA with a VVC prosthesis were analyzed retrospectively.
Results
In primary TKA, 29 cases (1.6%) in 27 patients (6 male and 21 female) used VVC prosthesis. Two patients underwent a VVC prosthesis on both knees. The mean age of the patients was 63.4 years old (34–79 years). The mean flexion contracture was 16.2° (-20°–90°), and the mean angle of great flexion was 111.7° (35°–145°). The situations requiring a VVC prosthesis were severe valgus deformity in 10 knees, knee stiffness requiring extensive soft tissue release in 10 knees, previously injured collateral ligaments in five knees, and distal femoral bone defect due to avascular necrosis in four knees. The mean tibiofemoral angle was 25.7° (21°–43°) in 10 cases with a valgus deformity. The mean flexion contracture was 37.5° (20°–90°), and the mean range of motion was 48.5° (10°–70°) in 10 cases with knee stiffness.
Conclusion
The preparation of VVC prosthesis is recommended, even for primary TKA in cases of severe valgus deformity (tibiofemoral angle>20°), stiff knee (the range of motion: less than 70° with more than 20° flexion contracture), and the cases with a previous collateral ligament injury. This information will help in the preparation of adequate TKA prostheses for unusual unstable situations.

Keyword

knee arthroplasty; constrained prosthesis; valgus deformity; knee stiffness