Physeal-Sensitive MRI Analysis Shows that an All-Inside, Anterior Cruciate Ligament Reconstruction in Skeletally Immature Athletes is Safe to the Physis

Abstract

Anterior cruciate ligament (ACL) reconstruction in skeletally immature patients poses a potential risk of growth disturbance due to iatrogenic physeal injury. Multiple physeal-sparing techniques have been described but none to our knowledge combine the benefits of anatomic reconstruction and socket fixation, without violation of either the femoral or tibial physis. The purpose of this study was to evaluate the safety and efficacy of an all-inside, physeal-sparing ACL reconstruction technique in skeletally immature athletes. Twenty-three skeletally immature patients (mean chronologic age 12.6 years, [range 10-15]) were prospectively evaluated following an all-inside ACL reconstruction utilizing hamstring autograft. The mean bone age (Greulich and Pyle method) was 13.5 years. There were 8 females and 15 males. Fifteen patients had an all-epiphyseal (AE) ACL reconstruction and 8 patients had a partial transphyseal (PTP) ACL reconstruction, which spared the femoral physis but crossed the tibial physis. The PTP option was reserved for patients with minimal proximal tibial growth remaining. The mean duration of residual distal femoral growth for patients in the AE group was 2.7 years compared to 1 year in the PTP group. At a mean follow-up of 12.6 months (range 6-24), graft survival, growth arrest, and the amount of physeal violation was quantified using a previously-validated model obtained from 3-D fat suppressed spoiled gradient-recalled echo (SPGR) MRI sequences. Angular deformity and leg length discrepancy were evaluated using full-length standing radiographs. Minimal post-operative tibial physeal changes were seen in 10 of 15 patients in the AE group and by definition; all patients in the PTP group. The mean area of tibial physeal disturbance (+/- SD) was 42.4 +/- 38.6 mm2 (mean 1.7% of total physeal area) in the AE group compared to 216.7 +/- 129.1 mm2 (mean 7.3% of total physeal area) in the PTP group (p = 0.003). Minimal post-operative femoral physis encroachment was seen in one case of both groups resulting in a mean physeal disturbance of 1.5%. No cases of growth arrest, tibial fracture, articular surface violation or avascular necrosis were noted on MRI in either group. Graft survival was 100% amongst the entire cohort. The mean leg length discrepancy was -0.7mm and there were no cases of angular deformity. Our data suggests all-inside ACL reconstruction is a safe and effective technique for skeletally immature athletes at short-term follow-up. Physeal-specific MRI reveals minimal growth plate disturbance following AE reconstruction relative to a PTP technique; however, both techniques reveal no evidence of significant complications.