The Amount of Peroneus Longus Insertion Resection With Modified Lapidus Procedure for Severe Hallux Valgus: Comparative Radiographic Study of 2 Different Osteotomy Methods.

BACKGROUND: Modified Lapidus procedure is well established for severe hallux valgus (HV). Nonetheless, postoperative recurrence remains a clinical concern. Peroneus longus (PL) functions as a dynamic stabilizer of the first ray, and its insertion at the base of the first metatarsal may be partially resected during osteotomy. Notably, PL dysfunction may contribute to recurrence by contributing to postoperative first ray instability. Nevertheless, extent of PL insertion resection during modified Lapidus procedure has not been quantified. This study aimed to evaluate the extent of resected PL insertion during modified Lapidus procedure.

METHODS: We retrospectively reviewed 80 feet from 74 patients with severe HV. We simulated 2 osteotomy methods: lateral wedge osteotomy at the base of the first metatarsal (M-method) and lateral wedge osteotomy at the distal medial cuneiform (C-method). On radiographs, resected lateral edge length of the first metatarsal (rM1-length) to correct intermetatarsal angle (IMA) to 0° was measured. Based on the rM1-length, 3-dimensional computed tomography models were used to measure whole PL insertion length, resected PL insertion length (rPL-length), and percentage of resected PL insertion (%-rPL). These parameters between the M-method and the C-method were compared. Cutoff value of the IMA for diagnosing feet with %-rPL greater than 50% using the M-method was evaluated.

RESULTS: rM1-length, rPL-length, and %-rPL were significantly greater with the M-method than with the C-method (all P < .001). Notably, the mean %-rPL with the M-method exceeded 50%. The IMA cutoff value was 21.4°; however, with the numbers available, no statistically significant difference was detected in the rPL-length and %-rPL with the C-method above and below this cutoff.

CONCLUSION: Lateral wedge osteotomy at the first metatarsal may result in substantial PL insertion resection during the modified Lapidus procedure. Lateral wedge osteotomy of the medial cuneiform bone may better preserve PL insertion and potentially have implications for first ray stability.