Summary

Among patients with higher lateral tibial slope more than seven, those with a larger notch width index demonstrated better functional outcome than patients with a lower notch width index

Abstract

【Introduction】 ACL reconstruction stands as the gold-standard treatment for ACL injuries. However, existing literature highlights certain risk factors that could impact the outcomes of ACL reconstruction. Specifically, a high lateral tibial slope may elevate stress on the reconstructed ACL graft, exacerbating pivot instability and potentially leading to poorer functional outcomes and a higher failure rate post-ACLR. The notch width index (NWI) is identified as another predisposing factor that may influence ACLR outcomes. Despite this, limited studies delve into the role of NWI in patients with a high tibial slope.

【Materials and Methods】 From 2010 to 2014, we identified patients diagnosed with primary ACL injuries treated with ACL reconstruction. Inclusion criteria comprised patients with a pre-operative lateral tibial slope in MRI greater than seven. Patient demographic data were recorded, and measurements of lateral tibial slope and notch width index were obtained from pre-operative MRI using proton density series. Patient-reported outcomes were assessed using post-operative Lysholm score, knee IKDC score, and Tegner score.

【Results】 A total of 122 patients were included, with an average age of 30.6 years at the time of surgery. Patients with NWI less than 0.23 (n=43) demonstrated average scores of 77.6, 68.3, and 7.0, respectively. In contrast, patients with NWI exceeding 0.25 (n=48) showed average scores of 83.9, 74.4, and 7.83. A significant difference was observed between patients with NWI<0.23 and NWI>0.25 in post-operative Lysholm score (p= 0.004) and IKDC score (p= 0.001).

【Discussions】 Cruz et al. reported that an increased posterior tibial slope independently constitutes a risk factor for graft rupture in anterior cruciate ligament reconstruction. Wang et al. found that the contralateral ACLR limb had a smaller ACL size and narrower relative femoral notch size compared to healthy individuals. A review study by Bongbong et al. concluded that posterior tibial slope and notch width are associated with and predictive of outcomes after ACLR. Our study revealed that patients with high tibial slope accompanied with higher NWI demonstrated better functional outcomes after ACLR in patients with low NWI.

【Conclusions】 Patients undergoing ACLR with a high lateral tibial slope may exhibit inferior functional outcomes. However, those with a larger NWI demonstrated better patient-reported outcome measures (PROMs) than patients with a lower NWI