Increased medial and lateral tibial posterior slopes are independent risk factors for graft failure following ACL reconstruction.

PURPOSE: To analyze the contribution of increased lateral (LTPS) and medial tibial slopes (MTPS) as independent risk factors of graft failure following anterior cruciate ligament (ACL) reconstruction. MATERIALS AND METHODS: Fifty-seven patients with graft failure after ACL reconstruction who underwent revision surgery between 2009 and 2014 were enrolled and matched to a control group of 69 patients with primary anatomic successful ACL reconstruction. Patients were matched based on age, sex, date of primary surgery and graft type. LTPS and MTPS were measured on MRI in a blinded fashion. Tibial and femoral tunnel positions were determined on CT scans. Independent t test was used to compare the MTPS and LTPS between subgroups. Risks of graft failure associated with an increasing MTPS and LTPS were analyzed using binary logistic analysis. RESULTS: The means of LTPS (7.3°) and MTPS (6.7°) in the graft failure group were found to be significantly greater than in the control group (4.6° and 4.1°, respectively; p = < 0.001). Non-anatomic and anatomic tunnel positions were found in 42 cases (73.7%) and 15 cases (26.3%), respectively. There were no significant differences in MTPS or LTPS between patients with anatomic and non-anatomic tunnel positions within the graft failure group. An increase of the MTPS of 1° was associated with an 1.24 times increased likelihood of exhibiting graft failure [95% CI 1.07-1.43] (p = 0.003) and an increase of the LTPS of 1° was associated with an 1.17 times increased likelihood of exhibiting graft failure [95% CI 1.04-1.31] (p = 0.009). The increased risk was most evident in patients with a lateral tibial posterior slope of ≥ 10°. CONCLUSIONS: Increased LTPS and MTPS are independent risk factors for graft failure following ACL reconstruction regardless whether tunnel position is anatomic or non-anatomic. This information may be helpful to clinicians when considering slope correction in selected revision ACL reconstruction procedures.

High variability of tibial slope measurement methods in daily clinical practice: Comparisons between measurements on lateral radiograph, magnetic resonance imaging, and computed tomography.

BACKGROUND: Tibial slope measurements are important in guiding clinical decisions in the field of orthopedic surgery. However, there are multiple techniques across different medical imaging modalities and little is known about its impact on result and validity of the measurement. Therefore, the purpose of this study was to compare tibial slope measurements from lateral radiographs, magnetic resonance imaging (MRI) and computed tomography (CT) scans in order to better assess the clinical significance of measured tibial slope values. METHODS: Twenty patients with complete medical imaging (lateral radiographs, MRI, CT scans) undergoing anterior cruciate ligament revision surgery were included. The tibial slope of the medial and lateral plateau were measured and compared using the methods of Dejour et al. and Utzschneider et al. on lateral radiographs, by Hudek et al. and Hashemi et al. on MRI and CT scans, and by Zhang et al. on three-dimensional reconstructions of CT scans. RESULTS: Mean differences up to 5.4 ± 2.8° (P < 0.05) and 4.9 ± 2.6° (P < 0.05) between different measurement methods were found for the medial and lateral tibial slope, respectively. Depending on how the tibial shaft axis was defined, significant differences between the respective measurement methods and a relevant degree of variability were identified. Pearson correlation coefficients between the measurement methods varied distinctly from moderate to strong correlations. CONCLUSIONS: Tibial slope measurements have a high degree of variability and inaccuracy between imaging modalities and different measurement methods. Care must be taken when deciding on indications based on individual modality measurements.