Non-linear fitting of mechanical data for efficacy determination of single versus double bundle Achilles tendon grafts for PCL reconstructions.

The Posterior Cruciate Ligament (PCL) consists of two primary bundles and is the primary restraint to posterior tibial translation. The emergence of the Posterior Tibial Inlay Technique (PTIT) has demonstrated a mechanical advantage over the commonly used Tibial Tunnel Method (TTM). This study was designed to investigate the effects on knee mechanics from both a Single-bundle (SB) and Double-bundle (DB) Achilles tendon PCL reconstruction using a PTIT. The investigators hypothesized that a DB graft demonstrates a mechanical advantage compared to the SB graft. A materials testing machine provided six sequential loading cycles of 100 N while total translation was measured. The testing was conducted at 90 degrees, 60 degrees, 30 degrees and 10 degrees of flexion in neutral tibial rotation. While the mechanical advantages of the DB graft were detected, specifically at small laxity values and in the physiological range of normal gait, the additional complexity of the technique may clinically outweigh the mechanical advantages.