Muscle strength after the anterior cruciate ligament reconstruction via contralateral bone-tendon-bone autograft

PURPOSE: The anterior cruciate ligament (ACL) reconstruction via a contralateral bone-tendon-bone (C-BTB) autograft was introduced to encourage early return to sports. The purpose of this study is to evaluate whether primary contralateral BTB ACL reconstruction can be adapted for early return-to-sports modification by investigating the chronological changes of muscle strength after surgery. METHODS: Fifteen patients who had underwent C-BTB ACL reconstruction were compared with a matched group of 15 patients of ipsilateral BTB (I-BTB) ACL reconstruction. The clinical outcomes of the time of return-to-sports, Tegner activity scale and the rate of second ACL injuries, the tibial anterior translation measurement, and knee extension and flexion muscle strength were assessed. RESULTS: Within 12 months after surgery, 14 of 15 patients from both groups returned to preinjury sports. The median time to return to sports after surgery was 6.5 months in the C-BTB group and 8.0 months in the I-BTB group (p = 0.021). No significant difference was noted with regard to the Tegner activity scale, reinjury rate or mean instrumental anterior tibial translation. The quadriceps muscle strength in the ACL-reconstructed knee compared with the opposite knee in both groups at 5 months after surgery was 120.6% in the C-BTB group and 70.0% in the I-BTB group (p < 0.001). However, the quadriceps muscle strength of the non-reconstructed limb, which instructed the graft harvested knee in the C-BTB and the intact knee in the I-BTB group, compared with that of the preoperative uninjured limb, was 74.5% in the C-BTB group and 118.7% in the I-BTB group (p = 0.0021) 5 months after surgery. Moreover, the quadriceps muscle strength of the reconstructed knee compared with the preoperative normal limb was 88.8% and 81.5% in the C-BTB and I-BTB groups, respectively (p = 0.38). CONCLUSIONS: ACL reconstruction via the C-BTB autograft indicated better quadriceps muscle strength from early stage after surgery compared with I-BTB ACL reconstruction. However, the ostensible rapid symmetrical muscle strength recovery was attributed to strength deficits compared to the preoperative condition at the donor site limb and ACL-reconstructed limb. LEVEL OF EVIDENCE: Level: Level: 4.