Anatomic and biomechanical aspects of pie crusting posterolateral structures for valgus deformity correction in total knee arthroplasty

Correction of valgus deformity during total knee arthroplasty is usually carried out by releasing lateral supporting structures from the femoral side of the joint. A new technique has been advocated that involves multiple stabs of the scalpel blade or pie crusting of the posterolateral corner. It is the hypothesis of this study that the correction achieved by using this technique occurs when the lateral collateral ligament is effectively released and that the common peroneal nerve may be at risk. Using a cadaveric model with 6 knees tested, significant differences were determined between 2 separate pie crusting steps as well as between releasing the lateral collateral ligament and popliteus tendons. Anatomic dissection studies also showed that in full extension the peroneal nerve may be less than the depth of a number 1 1 blade (16 mm) from the posterolateral corner, and the nerve may be at risk during this technique. These results show that major deformity correction obtained using the pie crusting technique is probably through effective release of the lateral collateral ligament.