Background Anatomical knowledge of the anterior cruciate ligament (ACL) and patellar ligament (PL) is critical for surgical planning, particularly in ligament reconstruction procedures. This study aimed to measure normative lengths of ACL and PL using MRI among individuals without knee pathology in a tertiary care setting. Methods This retrospective, record-based observational study analysed knee MRI scans of 112 patients aged >18 years, selected from data archives at a tertiary hospital. Patients with known ligament injuries, degenerative disease, or prior surgery were excluded. ACL and PL lengths were measured in the sagittal plane using standardized radiological protocols. Data were analyzed for side- and gender-wise variation. Results The mean ACL length was 36.89 ± 1.00 mm on the right and 36.89 ± 0.95 mm on the left knee. The mean PL length was 45.24 ± 1.27 mm on the right and 45.34 ± 1.10 mm on the left knee. No statistically significant differences were found between right and left sides or between genders. The ligament lengths remained highly consistent across the population studied. Conclusion The study establishes MRI-based normative values for ACL and PL lengths in a healthy South Indian population, with minimal inter-individual or gender-related variation. These values may serve as reliable references for preoperative planning in ACL reconstruction and graft selection. Further studies with larger sample size are necessary to confirm these findings.

Patellar ligament, Anterior cruciate ligament.