Abstract
Performing a total knee arthroplasty in a patient with a flexion contracture or recurvatum deformity requires from the surgeon an adequate knowledge of the principles of flexion – extension space balancing.
In the standard TKA procedure, adequate balancing between the flexion and extension space is usually easily achieved, leading to an equal and symmetrical space both in flexion and extension, which results in a stable knee and maximal range of motion after implantation of the prosthetic components. The situation is different in the knee with a flexion contracture or recurvatum, where the extension space is relatively smaller (flexion contracture) or greater (recurvatum) than the flexion space. In both of these situations, the flexion and extension space should be balanced by the surgeon in order to avoid an important deficit in range of motion or an instability problem. Several surgical techniques are available for this.
In the knee with a flexion contracture, the extension space is relatively too small. Adequate removal of posterior osteophytes will increase the extension space, and this should be the first step in the flexion – extension space procedure (1). Next, the collateral structures should be balanced, with release of the tight structures that are effective in extension only (2).
These are predominantly the iliotibial band in the valgus knee, and the posterior oblique ligament in the varus knee. If these 2 steps are not sufficient, proximalisation of the femoral component by 2 to 3mm may be required (step 3), or a formal release of the posterior capsule from the posterior femoral condyles (4). When an anterior reference system is used, the surgeon can also decide to use a slightly larger femoral component with a slightly increased tibial resection to equalise the gaps (5).
In the knee with a recurvatum deformity, the extension space is relatively too large. In this situation, distalisation of the femoral component by removing 2 mm less distal femoral bone, will decrease only the extension space without altering the flexion space (1). In case of anterior referencing, the use of a slightly undersized femoral component will further equalise the gaps (2). Just using a thicker tibial insert to fill up the extension space, while increasing the flexion space by resecting the PCL or increasing the tibial slope, may be another option in the modest recurvatum knee (3).
Theses abstracts were prepared by Professor Dr. Frantz Langlais. Correspondence should be addressed to him at EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
