Higher Posterior Tibial Slope and Lower Medial Proximal Tibial Angle of the Knee Are Associated With Delayed Graft Maturation After Anterior Cruciate Ligament Reconstruction Surgery With Hamstring Autograft.

PURPOSE

To relate bone shape with anterior cruciate ligament (ACL) graft maturation, as evaluated by quantitative magnetic resonance imaging.

METHODS

We retrospectively evaluated patients aged 18 to 60 years who underwent ACL reconstruction with a hamstring autograft with doubled semitendinosus and gracilis at our institution between 2018 and 2020 with isolated ACL injuries. All patients had a minimum follow-up period of 2 years. To evaluate alignment, radiographs of the knee were taken preoperatively. Postoperative 3T magnetic resonance imaging and patient-reported outcome scores were acquired at 2 years after surgery. A combined T1ρ/T2 quantification sequence and a 3-dimensional multiecho ultrashort echo time (UTE) cone sequence were obtained in a sagittal-oblique plane for better assessment of the ACL graft. After acquiring images, a manual segmentation for the ACL graft was performed to assess T1ρ, T2, and UTE T2∗ relaxation times. Correlations between radiographic parameters or patient-reported outcome scores and T1ρ, T2, and UTE T2∗ values were tested with Pearson correlation coefficients. Significance was defined as P < .05.

RESULTS

Participants were 28 patients (12 men and 16 women) who had a mean (SD) age of 34.3 (8.5) years and body mass index of 24.4 (4.5). A significant correlation was found between the preoperative posterior tibial slope (PTS) and the T1ρ, T2, and UTE T2∗ relaxation times (r = 0.41, P = .033; r = 0.47, P = .014; and r = 0.41, P = .030), indicating inferior graft maturation in patients with a higher PTS. Furthermore, a negative correlation was identified between the preoperative medial proximal tibial angle and the T1ρ, T2, and UTE T2∗ relaxation times (r = -0.39, P = .039; r = -0.46, P = .018; and r = -0.43, P = .024), indicating inferior graft maturation in patients with greater varus knee alignment.

CONCLUSIONS

The study findings suggest that an increased PTS and a lower medial proximal tibial angle are associated with inferior graft maturation as per T1ρ, T2, and UTE T2∗ imaging at 2 years post-ACL reconstruction.

LEVEL OF EVIDENCE

Level IV, retrospective case series.