Does The Posterior Tibial Slope Influence Knee Functionality In The ACL-Deficient And ACL-Reconstructed Knee

Purpose: A higher posterior tibial slope can potentially result in kinetic and kinematic changes of the knee. These changes may influence knee functionality in ACL-deficient and ACL-reconstructed subjects. The purpose of this study was to investigate the relationship between knee functionality and posterior tibial slope in ACL-deficient and ACL-reconstructed subjects. Methods: Subjects with isolated ACL injuries and subjects who underwent ACL-reconstruction with bone-patella-bone-tendon (BPTP) between 18 and 24 months post surgery were included in the study. Posterior tibial slope was measured on a lateral radiograph using the posterior tibial cortex as a reference. The Cincinnati scoring system was used to assess knee functionality. Results: 44 ACL-deficient patients with a mean age of 26.6 years and 24 ACL-reconstructed patients with a mean age of 27.2 (25–49) years were included. The posterior tibial slope in the ACL-deficient group averaged 6.10±3.57 degrees (range 0–17 degrees) and 7.20±4.49 degrees (range 0–17) in the ACL-reconstructed group. An anterior tibial slope was not measured in any of the participants. The mean Cincinnati score in the ACL-deficient subject was 62.0±14.5 and 89.3±9.5 in the ACL-reconstructed subject. There was a moderate but non-significant correlation (r=0.47) between knee functionality and slope in the ACL-deficient subject. Dividing posterior tibial slope into intervals, a strong significant correlation (r=0.91, p=0.01) was observed between knee functionality and slope. There was a weak but non-significant correlation (r=0.24) between knee functionality and slope in the ACL-reconstructed patient. Dividing posterior tibial slope into intervals (0–4, 5–9, >10) a strong and significant correlation (r=0.96, p=0.0001) was observed between knee functionality and slope. Conclusion: The results of this study suggest that subjects with a higher posterior tibial slope have higher knee functionality. This is in contrast to previous research.