A biomechanical comparison of 3 reconstruction techniques for posterolateral instability of the knee in a cadaveric...

The objective of this study was to compare the varus and external rotatory laxity of reconstructed knees by use of 3 different reconstruction techniques that address posterolateral instability of the knee: popliteus tendon (PT) and lateral collateral ligament (LCL) reconstruction, PT and popliteofibular ligament (PFL) reconstruction, and PFL and LCL reconstruction.

We divided 36 fresh-frozen cadaveric knees into 3 groups of 12, and each group was assigned to a reconstruction technique: PT-LCL reconstruction with the posterior tibialis tendon, PT-PFL reconstruction with the patellar tendon and bone (Warren technique), and PFL-LCL reconstruction with the semitendinosus tendon (Larson technique). Each specimen was fixed with an Ilizarov external fixator and mounted on a custom-designed apparatus that was made to measure posterolateral instability of the knee, that is, external rotatory and varus laxity in the intact state, after cutting, and in the postoperative state at every 30 degrees from 0 degrees to 90 degrees .

There were no significant differences between the 3 techniques with external rotation and varus laxity in all specimens.

PT-LCL reconstruction was comparable to the other 2 established techniques: PT-PFL reconstruction (Warren technique) and PFL-LCL reconstruction (Larson technique). However, the original strength of the native knee could not be achieved with any of the techniques.

All techniques restored the posterolateral stability of the knee to near normal, with none of them being superior.