Patella tendon anterior tibial cortex angle (PTATA): An indirect marker of anterior cruciate ligament (ACL) tear?

BACKGROUND

Anterior cruciate ligament (ACL) injuries are common in high-impact sports. While direct MRI evaluation is preferred for diagnosis, indirect signs are often crucial. The Patella Tendon Anterior Tibial Cortex Angle (PTATA) could serve as an additional indirect marker of ACL injury, reflecting altered knee biomechanics. We hypothesise that knees presenting complete ACL rupture will exhibit a smaller PTATA on MRI due to the associated anterior tibial translation.

METHODS

We reviewed 100 knee MRI scans of patients under the age of 30 years, presenting with acute knee injuries and clinical signs suggestive of ACL tear. Patients were divided into three groups: intact (Group 1), partial (Group 2), and full-thickness ACL tear (Group 3). The PTATA was measured on sagittal PDFS sequence for all patients and the mean PTATA values for each group were compared using a one-way ANOVA test.

RESULTS

Group 1 (n = 78) had a mean PTATA of 32.32° (SD ± 6.34°, SEM ± 0.72°), Group 2 (n = 5) showed a mean of 34.00° (SD ± 5.15°, SEM ± 2.30°), while Group 3 (n = 17) demonstrated a significantly lower PTATA of 25.12° (SD ± 5.17°, SEM ± 1.25°). Group 3 had a statistically significant reduction in PTATA compared to Groups 1 and 2 (p < 0.05).

CONCLUSION

PTATA provides an indirect marker of ACL injury, with values below 30° demonstrating a significantly higher likelihood of a full-thickness ACL tear. This measurement is simple, easily reproducible on routine MRI and could complement existing MRI diagnostic criteria.