| Abstract ID |
| 20260048 |
| Category |
| Knee: ACL |
| Preferable Presentation |
| Both |
| Title |
| BONE TUNNEL MICROARCHITECTURE IS CORRELATED WITH EARLY FUNCTIONAL RECOVERY AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION: A PROSPECTIVE HR-PQCT COHORT STUDY |
| Author |
|
| Presenter |
| TianYi ZANG |
| Abstract |
| Background The biological healing of the bone tunnel is an important determinant of graft stability and long-term success in anterior cruciate ligament reconstruction (ACLR). While clinical evidence favors the healing interface of bone-patellar tendon-bone grafts, soft-tissue grafts may rely on tendon-to-bone integration, a process susceptible to poor anchorage and graft laxity. Conventional imaging assessments, such as radiographs and standard computed tomography, focus on tunnel geometry (widening), which correlates poorly with clinical outcomes. Consequently, there is a gap in understanding how the bone tunnel healing quality affects early recovery. High-resolution peripheral quantitative computed tomography (HR-pQCT) offers a non-invasive solution to quantify these essential microarchitectural properties. Objectives We hypothesized that the microarchitectural parameters of the femoral and tibial bone tunnels, quantified by HR-pQCT, would be directly correlated with objective functional performance and patient-reported outcomes at 4 and 6 months postoperatively. Study design In this prospective cohort study, 50 patients (aged 18-50) undergoing primary hamstring autograft ACLR were assessed at 4 and 6 months postoperatively. HR-pQCT was used to quantify specific bone tunnel parameters, including Bone Volume/Total Volume (BV/TV), Trabecular Thickness (Tb.Th), Trabecular Number (Tb.N), Trabecular Separation (Tb.Sp), and tunnel enlargement ratio. Clinical performance was evaluated using isokinetic muscle strength tests (60°/s), single-leg hop tests, and ultrasound muscle thickness assessments. Subjective outcomes included the International Knee Documentation Committee (IKDC) score. Receiver operating characteristic (ROC) analysis was performed to identify predictive thresholds for good functional recovery, defined by a Limb Symmetry Index (LSI) of 0.7 at 4 months and 0.8 at 6 months. Results At 4 months, HR-pQCT analysis showed that femoral BV/TV (r= 0.361, p=0.010) and Tb.Th (r= 0.333, p=0.018) were positively correlated with knee extension strength. Conversely, the tibial tunnel enlargement ratio was negatively correlated with strength (r=-0.380, p=0.007). Patient-reported outcomes demonstrated similar structural findings; tibial Tb.N (r= 0.339, p=0.016) correlated positively with IKDC scores, while tibial Tb.Sp (r=-0.367, p=0.009) showed a negative correlation. ROC analysis identified femoral BV/TV at 4 months as a significant predictor of functional recovery (Area Under the Curve [AUC]= 0.680, p=0.027), with a cutoff value of 0.2607 providing a specificity of 86.7%. At 6 months, the predictive strength of bone volume decreased, while femoral Tb.N emerged as a stronger predictor (AUC= 0.645). Conclusions The microarchitectural quality of the bone tunnel, as assessed by HR-pQCT, is modestly correlated with early functional recovery after ACLR, particularly at 4 months postoperatively. HR-pQCT assessment provides a novel, biology-informed metric to guide personalized rehabilitation, allowing clinicians to identify patients with poor bone healing early and adjust therapy protocols accordingly. |