Incomplete graft maturation at 1 year after all‐inside anterior cruciate ligament reconstruction using peroneus longus autograft: A prospective diffusion tensor imaging study

PURPOSE: This study evaluated the maturation of the peroneus longus (PL) tendon autograft by quantifying the key diffusion tensor imaging (DTI) parameters: fractional anisotropy (FA) and apparent diffusion coefficient (ADC) at 1 year of follow-up in patients undergoing all-inside anterior cruciate ligament (ACL) reconstruction surgery. METHODS: Magnetic resonance imaging (MRI) of the knee with DTI sequences was done at 1 year of follow-up for 50 patients (mean age 26.6 ± 8.5 years; 41 males + 9 females), who underwent ACL reconstruction using PL tendon autograft. FA and ADC at different parts of the graft (femoral, mid-substance and tibial) were determined with regions of interest (ROI)-based measurements after assessing the fibre morphology on the proton density fat-saturated (PDFS) images. Figueroa scores using the conventional MRI sequences were also calculated at 1 year of follow-up and compared with the DTI parameters. The Tegner-Lysholm and knee society scores were used to evaluate functional outcomes. RESULTS: mm²/s, both different from the reported values for native ACL. The majority of patients (35/50) had a Figueroa score of 4, indicating adequate but incomplete graft maturation. The FA and ADC values of the three individual regions of the graft, as well as the overall mean value, did not show any significant difference between the three Figueroa score groups (Figueroa score 3 vs. 4 vs. 5). There was a significant improvement (p < 0.001) in the patient-reported outcome measures at the final follow-up. CONCLUSION: DTI and conventional MRI parameters showed substantial but incomplete graft maturation, despite excellent functional recovery, at 1 year of follow-up. Our study supports the use of PL tendon as a reliable graft option, demonstrating acceptable graft maturation and favourable functional outcomes. Advanced imaging may assist in individualised return-to-sport decision-making. LEVEL OF EVIDENCE: Level II.