Soft tissue balancing in total knee arthroplasty

Abstract

A good outcome in total knee arthroplasty depends on many factors: joint alignment, range of motion, patellar tracking and ligament stability. A correct soft tissue balance keeps the joint aligned in flexion and extension, and therefore constitutes the most important factor for durability of the implant. Indeed, incorrect soft tissue balancing is the primary cause of early implant failure necessitating revision surgery. Soft tissue releases, serving to correct imbalances, are performed until the flexion and extension gaps appear symmetrical and balanced. A knee is considered perfectly balanced when the flexion and extension gaps are perfectly rectangular and all the measurements are absolutely equal.

Keywords: balance; ligament; total knee arthroplasty; valgus; varus.

Fig. 1

Severe varus knee deformity showing both ligament and bony alterations.

Fig. 2

Osteophytes influence soft tissue tension and do not allow proper evaluation of balancing during surgery.

Fig. 3

Flexion space is balanced by rotating the femoral component to equalize the filling effect of the femoral component in flexion. Proper instruments are needed to reach a symmetrical gap.

Fig. 4

Balancing of varus knee after release of both anterior and posterior structures.

Fig. 5

Lateral collateral ligament release using the pie crusting technique in a valgus knee.