Impact of Time After the Injury of Anterior Cruciate Ligament on Vascular and Bone Quality at the Femoral Insertion Site: A Prospective Histological Study

Background Anterior cruciate ligament (ACL) injuries are among the most common knee injuries; however, current knowledge often overlooks the effects on the femur following a rupture. This study aimed to assess whether delaying the surgical procedure may lead to a decline in blood supply and bone quality at the ACL attachment site within the femur. Methods This prospective study enrolled 50 adult patients (22–53 years) undergoing ACL reconstruction and 10 control patients (55–65 years) undergoing total knee arthroplasty. A 4.5 mm femoral bone block was harvested during surgery and analyzed histologically. Blood vessel density and CD34-positive cell clusters per mm² were quantified using ImageJ™ software. Bone quality was assessed via lacunar density analysis. Statistical comparisons included correlation analysis and ANOVA with age and time since injury as covariates. Results Patients operated on within 9 months of injury had significantly higher blood vessel density (5 vs. 2 vessels/mm², p  < 0.01) and CD34 cluster counts compared to those with delayed surgery. Bone quality decreased with increasing time since injury, with the strongest deterioration observed in patients aged ≤ 38 years. Conclusions Delaying ACL reconstruction beyond 9 months is associated with significantly reduced vascularity and bone quality at the femoral attachment. These findings highlight the importance of timely surgical intervention, especially in younger patients, to preserve tissue quality and optimize surgical outcomes. Level of evidence: II