TIBIAL PHYSEAL RESPECTING TUNNEL DRILLING TECHNIQUE FOR ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION IN SKELETALLY IMMATURE ATHLETES

BACKGROUND: ACL reconstruction is common in young patients. HYPOTHESIS/PURPOSE: To report outcomes of a novel tibial drilling technique using an inside-out socket drilling method, with a drill pin and epiphyseal socket drilling in skeletally immature patients. Minimizing disruption to the tibial physis, attempting to prevent growth disturbance with an anatomic ACL that eliminates the graft bend angle at the tibial tunnel. METHODS: We used a standard all-epiphyseal drilling technique for femoral preparation. The tibial drill guide, set at 55° for our tibial physeal respecting approach, is positioned in the posterior third of the ACL footprint in-line with the posterior aspect of the lateral meniscus anterior root. The FlipCutter (Arthrex Inc., Naples, FL) is drilled from the external proximal tibia. Thus, only a 3.5mm diameter tunnel crosses the proximal tibial physis. With the FlipCutter deployed, the cutting radius is checked to confirm proper position without risk of damage to the meniscal root, PCL, or articular cartilage. With fluoroscopic guidance, the tibial socket is drilled from the intra-articular surface towards the physis, stopping proximal to the physis. This results in a 15 to 20 mm all-epiphyseal socket length. We collected demographics, re-tear rate, physeal arrest (partial/complete), and patient reported outcomes in order to understand potential problems and mid-term outcomes of this procedure. RESULTS: Eight male patients were included in the study (average age=10.6±1.5 years). All patients had radiographs >6months post-surgery, and no patient had a clinically significant leg length discrepancy (>2cm) or deformity. The two patients followed >24months post-operatively were cleared to return to sports by one year. No patients demonstrated a positive Lachman or pivot shift test at >6months follow-up. No Patients had a ROM deficit at >6months follow-up. Five patients completed Pedi-IKDC and Lysholm assessments (time from surgery=16.2months+10.6months; range 7–28.8months). Average IKDC and Lysholm scores were 88+10 and 95+9, respectively. There were no graft ruptures in the cohort (average follow-up: 13.8months±8.9 months; range 6.8–30.6months). CONCLUSION: Our preliminary data from this novel tibial physeal respecting technique suggest it may be appropriate for skeletally immature patients with sufficiently large enough femoral epiphyses to hold a 10mm graft tunnel without disturbance to the physis. This technique seems successful in terms of graft survival, patient reported outcomes, and no growth disturbance within 2 years of surgery, although we recognize our small sample size as a limitation. Further studies will better evaluate long-term outcomes of this pediatric ACLR technique.