Exogenous transforming growth factor beta 1 alone does not improve early healing of medial collateral ligament in rabbits.

OBJECTIVE To determine whether transforming growth factor beta 1 (TGF-beta1) improves early ligament healing. DESIGN Experimental, controlled study of medial collateral ligaments (MCLs) in rabbits' knees. SETTING Research laboratory. SUBJECTS Sixteen skeletally mature, New Zealand White female rabbits. INTERVENTIONS Ten rabbits had a standardized gap injury made in the MCL of both knees. Three weeks later, a second operation was performed to inject 7 microg of TGF-beta1 in a carrier solution into the right knee MCL, while the left knee MCL was injected with carrier alone. The rabbits were killed 3 weeks after the injection of TGF-beta1 (6 weeks after the original injury). Six of the rabbits (12 knees) had no operation on the MCL and served as external normal controls. OUTCOME MEASURES Biomechanical measures of the femur-MCL-tibia complex. Histologic evaluation of MCL cell and matrix organization. Transmission electron microscopy measures of MCL fibril diameters. RESULTS There were no statistically significant differences in the biomechanical measures, fibril diameter distributions and histologic evaluation of the injured MCLs treated with TGF-beta1 or carrier alone. Both groups of injured MCLs were significantly different from normal MCLs. CONCLUSIONS The results indicate that the dosage and route of delivery of TGF-beta1 did not lead to overt improvement in the healing of the injured MCL. Whether different doses or delivery methods, alone or in combination with TGF-beta1, or other growth factors would lead to improvement remains to be determined.