The effect of accelerated, brace free rehabilitation on bone tunnel enlargement after ACL reconstruction using hamstring tendons: a CT study.

The mechanism of bone tunnel enlargement following anterior cruciate ligament (ACL) reconstruction is not yet clearly understood. Many authors hypothesized that aggressive rehabilitation protocols may be a potential factor for tunnel enlargement, especially in reconstructions performed with hamstrings autograft. The purpose of this study was to evaluate the effect of a brace free rehabilitation on the tunnel enlargement after ACL reconstruction using doubled semitendinosus and gracilis tendons: our hypothesis was that early post operative knee motion increases the diameters of the tibial and femoral bone tunnels. Forty-five consecutive patients undergoing ACL reconstruction for chronic ACL deficiency were selected. All patients were operated by the same surgeon using autologous doubled semitendinosus and gracilis tendons and the same fixation devices. Patients with associated ligaments injuries and or severe chondral damage were excluded. The patients were randomly assigned to enter the control group (group A, standard post operative rehabilitation) and the study group (group B, brace free accelerated rehabilitation). A CT scan was used to exactly determine the diameters of both femoral and tibial tunnels at various levels of lateral femoral condyle and proximal tibia, using a previously described method. Measurements were done by an independent radiologist in a blinded fashion the day after the operation and at a mean follow- up of ten months (range 9-11). Statistical analysis was performed using paired t-test. METHODS The mean femoral tunnel diameter increased significantly from 9.04±0.05 mm (post op) to 9.30±0.8 mm (follow-up) in group A and from 9.04±0.03 mm to 9.94±1.12 mm in group B. The mean tibial tunnel diameter increased significantly from 9.03±0.04 mm to 10,01±0.80 mm in group A and from 9.04±0.03 mm to 10.60±0.78 mm in group B. The increase in femoral and tunnel diameters observed in the study group was significantly higher than that observed in the control group. RESULTS Our results suggest that bone tunnels enlargement after ACL reconstruction using hamstrings autograft can be increased by an accelerated, brace free, rehabilitation protocol.