Middle Eastern male ACL-deficient patients exhibit steeper posterior tibial slope than European counterparts: A cross-cultural matched cohort study

PURPOSE: The posterior tibial slope (PTS) is a key anatomical factor influencing anterior cruciate ligament (ACL) stability. Steeper slopes have been associated with increased anterior tibial translation (ATT) and a higher risk of graft failure following ACL reconstruction. Ethnic and regional differences in tibial morphology have been suggested, but comparative data across populations remain limited. This study aimed to compare medial PTS angles in ACL-deficient male patients from Europe and the Middle East.

METHODS: Ninety-four male patients undergoing primary ACL reconstruction (47 from Europe, 47 from the Middle East) were retrospectively included and matched 1:1 for age and sex. PTS was measured on true lateral radiographs using a validated method. Intra- and inter-rater reliability were assessed with intraclass correlation coefficients (ICCs).

RESULTS: The two cohorts were homogeneous in terms of key demographic variables. Surgical preferences differed significantly between groups in graft type ( p  < 0.0001) and meniscal repair rates ( p  = 0.002), with European patients more frequently undergoing meniscal procedures. However, the use of lateral extra-articular tenodesis was similar between groups ( p  = 0.80). PTS measurements showed good to excellent reliability (ICC 0.79-0.98). The Middle Eastern cohort had a significantly higher mean PTS than the European group (12.9 ± 3.4° vs. 10.3 ± 3.8°, p  = 0.002). A larger proportion of Middle Eastern patients exceeded the 12° threshold considered biomechanically relevant (46.8% vs. 25.5%, p  = 0.04; odds ratio = 2.59). No significant difference was observed in bone marrow oedema ( p  = 0.42).

CONCLUSIONS: ACL-deficient male patients from the Middle East exhibited significantly steeper PTS angles compared to their European counterparts, with a higher proportion exceeding 12°. This anatomical difference reflects regional morphotype characteristics within the studied cohorts and highlights potential variability in tibial slope distribution across populations.

LEVEL OF EVIDENCE: Level III, retrospective matched cohort study.