Inside-out tibial tunnel drilling technique is a reliable approach for all-inside ACL reconstruction: A longitudinal MRI assessment

Abstract

Purpose: To longitudinally evaluate sockets localization, tunnel morphological changes and graft maturation after the inside-out tibial tunnel drilling technique for all-inside Anterior Cruciate Ligament Reconstruction (ACLR). We hypothesized that due the necessary angle for the inside-out reaming procedure, the described technique could input changes in the tibial socket. Methods: Fourteen knees treated with the same all-inside ACLR technique were randomly assigned for a magnetic resonance evaluation. All patients were operated by the same surgeon and performed the same follow-up rehabilitation protocol. Socket's localization, shape and widening, as well as graft maturation and integration, were evaluated intraoperatively at 6 months and 4 years after surgery. Results: Both femoral and tibial tunnels had an expected increase at 6 months follow-up. The widening was larger in the tibial tunnel (12.6 ± 10.0% vs. 9.1 ± 8.5%), yet this difference was not statistically different. Tibial tunnel was well centred in the tibial plateau and the integration of the graft was higher in the tibial socket. Four years after surgery, there was a general reduction of diameter in both tunnels. The tunnel occlusion rate was 33.3% for tibia and 16.7% for femur. Conclusions: Overall, our results show that within a 4-year follow-up period, the inside-out tibial tunnel drilling technique for all-inside ACLR represents a safe technique that did not influence the tibial socket position nor tunnel widening or graft maturation in the long term. Level of Evidence: Level IV.