Incidence of Flatfoot Deformity After Anterior Cruciate Ligament Reconstruction Using Peroneus Longus Autograft: A Mid-Term Observational Study
Ludwig Andre Pontoh, Ismail Hadisoebroto Dilogo, Andri Maruli Tua Lubis, Achmad Fauzi Kamal, Ihsan Oesman, Jessica Fiolin, Fahresa Hilmy, Mohammad Almer Sahala HutapeaBackground:
The peroneus longus tendon has emerged as an alternative autograft for anterior cruciate ligament reconstruction (ACLR), offering adequate graft diameter and favorable biomechanical properties. However, concerns remain regarding potential donor site morbidity, particularly the risk of medial longitudinal arch collapse following tendon harvest.
Purpose:
To evaluate the incidence of postoperative flatfoot following ACLR using a peroneus longus autograft and to assess its relationship with generalized joint laxity and other patient characteristics.
Study Design:
Case series; Level of evidence, 4.
Methods:
A total of 130 patients undergoing single-bundle ACLR using a peroneus longus autograft between May 2024 and December 2025 were prospectively followed. Foot posture was evaluated using weightbearing digital podograms. The Arch Index (AI) was used as the primary diagnostic criterion for flatfoot (AI >0.26). Additional indices, including the Staheli Index, Chippaux-Smirak Index, and Clarke angle, were also assessed. Generalized joint laxity was evaluated using the Beighton score. Comparisons between patients with and without flatfoot were performed using nonparametric statistical tests.
Results:
A total of 130 knees in 130 patients underwent single-bundle ACLR, and complete follow-up was conducted. Postoperative flatfoot was identified in 2 patients (1.5%; 95% CI, 0.2%-5.4%) based on the AI. No cases of flatfoot were observed in the contralateral foot. Exploratory analyses showed no significant association between flatfoot occurrence and Beighton score, body mass index, or other demographic variables. Footprint indices demonstrated variable flatfoot classification rates, with the AI showing the lowest prevalence.
Conclusion:
Our study showed that ACLR using a peroneus longus autograft carries a minimal risk of postoperative flatfoot (1.5%), with any structural footprint changes remaining entirely asymptomatic. These findings may allow surgeons to consider another autogenous source for ACLR.