The effect of preoperative rehabilitation exercises on postoperative bone mineral density, tendon-bone healing, and physical function after anterior cruciate ligament reconstruction: a multi-center randomized controlled clinical trial

PURPOSE: The impact of preoperative rehabilitation on bone mineral density (BMD) and tendon-bone healing in anterior cruciate ligament reconstruction (ACLR) patients is unknown. METHODS: A total of 53 ACL rupture patients were randomized into 2 groups (Control Group [CON, n = 27] and Exercise rehabilitation group [ER, n = 26]). The CON received conventional treatment, and the ER group received 6-week exercise on this basis. Subsequently, both groups underwent ACLR. At baseline, after 3, 6 and 12 months post-ACLR, the knee BMD, magnetic resonance imaging, and physical function were measured. RESULTS: The BMD of lateral femur condyle (LFC) in ER group was higher than CON group at 3 and 6 months post-ACLR (p = 0.004, 0.01). The signal/noise quotient (SNQ) of proximal and distal segments in ER group were lower than CON group at 6 and 12 months post-ACLR (p = 0.02, 0.03). The medial femoral condyle cartilage thickness in ER group was begun thicker than CON group at 3 months post-ACLR (p = 0.04). At 6 months post-ACLR, the relative peak torque of the quads and hamstrings, the balance composite score, the Lysholm and IKDC scores in the ER group were better than CON group (Quads p = 0.02; Hamstrings p = 0.01; balance p < 0.001; Lysholm p < 0.001; IKDC p < 0.001). The difference value of BMD from baseline to 3 months post-ACLR in medial femoral condyles (MFC) exhibited positive correlations with 6 and 12 months post-ACLR within distal autograft SNQ (p = 0.025; 0.011). CONCLUSION: ACLR patients who undergo preoperative rehabilitation can effectively delay the decline of BMD in the LFC, enhance the tendon-bone healing, improve the knee articular cartilage thickness and advance the physical function. The less the early BMD of MFC loss in early postoperative, the better the later tendon-bone healing within or near the tibial tunnel. TRIAL REGISTRATION: PRS, NCT05924178. Registered 28 May 2023, www. CLINICALTRIALS: gov.