Posterolateral anatomical reconstruction restored varus but not rotational stability: A biomechanical study with cadavers.

BACKGROUND AND AIM: Lesions to the posterolateral corner (PLC) of the knee are rarely isolated injuries, and they are potentially devastating, leading to progressive chondral injury, with important functional impairment. The objectives of this biomechanical study were to evaluate angular deformation with two loads and considering four flexion angles of the knee, varus and external rotation and in three situations of integrity, reconstruction and injury of posterolateral knee structures.

METHODS

The posterolateral structures of 10 cadaveric knees were submitted to three biomechanical assays: in the "intact condition", "injured", and "reconstructed". The technique used for the reconstruction was the one proposed by LaPrade et al., but with autografts of hamstring tendons instead. A device was designed to apply loads of 2 and 5Nm, with zero, 30°, 60° and 90° of knee flexion, in varus or in external rotation, measuring angular deformation with photogoniometry.

RESULTS

The anatomical reconstruction of the PLC proposed here did restore varus stability in all flexion angles (p<0.005), but not rotational stability. External rotation deformation at 90° was similar in all test conditions. In knee extension, external rotation was stabilized only at 2Nm. At 60°, external rotation was partially stabilized (p<0.05).

CONCLUSIONS

The anatomical PLC reconstruction using hamstring tendons restored varus but not external rotational stability.

CLINICAL RELEVANCE: The reconstruction of posterolateral corner injuries with autologous allografts is very important for regions were tissue banks are not available. This technique may be a first step to achieve this goal.