Posterior tibial slope has no impact on treatment outcome in anterior cruciate ligament revision patients

Purpose
To investigate the impact of posterior tibial slope (PTS) on postoperative outcome in an anterior cruciate ligament (ACL) revision cohort, based on sagittal knee stability and subjective, patient-reported knee function.

Methods
Lateral knee radiographs from 105 ACL revision patients (mean age 27.2 ± 6.5 years) were retrospectively reviewed and both medial and lateral posterior tibial slope was measured. Objective sagittal knee stability was based on Rolimeter measurements. The subjective knee function was obtained through the Knee Numeric-Entity Evaluation Score (KNEES-ACL), the Knee Injury and Osteoarthritis Outcome Score (KOOS) and Tegner Activity Scale (TAS) questionnaires. Objective anterior–posterior (AP) knee laxity was examined prior to ACL revision surgery and at a one-year follow-up, and the patient reported outcome measures (PROMs) were obtained prior to ACL revision surgery and after a two-year follow-up period.

Results
No correlation was found between medial PTS and knee stability before (0.16; 95% confidence interval [CI], −0.06 to 0.36, p = 0.15) or one year after ACL revision surgery (0.07; 95% CI, −0.14 to 0.27, p = 0.54). Likewise, no correlation was found between lateral PTS and knee stability before (0.30; 95% CI, 0.09–0.48, p = 0.01) and one year after ACL revision surgery (0.15; 95% CI, −0.06 to 0.35, p = 0.16). Likewise, there was no correlation between medial and lateral PTS and KOOS, KNEES-ACL and TAS. The mean lateral PTS was 2.6° steeper than the medial PTS (p < 0.05).

Conclusion
In the present study, PTS was not found to be associated with either sagittal knee stability or subjective knee function in ACL revision patients. Patients undergoing ACL revision surgery have a large mean difference between the medial and the lateral PTS.

Level of Evidence
Level IV.