Purpose: The purpose of this study was to determine the biomechanical effects of simulated immediate motion and weightbearing during rehabilitation on different double-bundle posterior cruciate ligament reconstruction (DB-PCLR) graft options.
Methods: Nine each of commercially prepared (allograft) Achilles tendon allografts, fresh-frozen (autograft) bone-patellar tendon-bone grafts, and fresh-frozen quadriceps tendon grafts were paired with commercially prepared anterior tibialis allografts, fresh-frozen semitendinosus grafts, and fresh-frozen semitendinosus grafts, respectively. Graft pairs were loaded to simulate early range of motion on a stationary bicycle, partial weightbearing (30 %), and full weightbearing.
Results: Acquired laxity (displacement, mm) between graft pairs was not significantly different during simulated early range of motion. However, during simulated partial weightbearing, the median acquired laxity of the patellar tendon/semitendinosus pair (1.06 mm) was significantly less than that of the quadriceps tendon/semitendinosus (1.50 mm, p = 0.01) and Achilles/anterior tibialis (1.44 mm, p = 0.003) graft pairs. During simulated full weightbearing, significantly less acquired laxity was observed for the patellar tendon/semitendinosus graft pair (2.38 mm) compared to the Achilles/anterior tibialis pair (4.85 mm, p = 0.04), but a significant difference was not observed compared to the QT/semitendinosus graft pair (3.91 mm, n.s.). There were no significant differences in the ultimate loads between any of the graft pairs.
Conclusions: Simulated early range of motion and early partial weightbearing did not result in clinically significant acquired graft laxity in common graft options utilized for DB-PCLR. However, simulated full weightbearing did result in clinically significant acquired graft laxity, and therefore, early rehabilitation protocols should avoid implementing full weightbearing that could contribute to graft failure.
Keywords: Allograft; Autograft; Double-bundle posterior cruciate ligament reconstruction; Range of motion; Rehabilitation; Weightbearing.