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.