Radiographic Comparison of Forefoot and Midfoot width changes with 4th generation Minimally Invasive Bunion Surgery versus the Modified Lapidus Procedure

Imad Najm, Matthew Towner, Togay Koç

Introduction: Minimally Invasive Bunion Surgery (MIBS) and the Modified Lapidus Procedure (MLP) have both been shown to treat bunions and narrow forefoot bony and soft tissue width. Both procedures stabilise the 1st Tarsometatarsal Joint (TMTJ). El Masry et al report an increase in proximal midfoot bony and soft tissue width associated with MIBS.

Aim: To compare forefoot and midfoot bony and soft-tissue width between MIBS and MLP.

Method: A retrospective review of 21 consecutive MIBS using 4th generation technique on 16 feet between March 2022 and August 2024 and 24 consecutive MLPs on 20 feet between July 2021 and June 2024 were performed. Radiographic data collection included pre- and post-operative HVA, IMA +/- proximal IMA, DMAA, Dist 1-2 (distance between 1st & 2nd metatarsal), forefoot bony (FFBW) & soft-tissue width (FFSTW), proximal/midfoot bony (MFBW) & soft-tissue width (MFSTW) and 1st:2nd Metatarsal ratio.

Results: For the MLP: IMA, HVA & DMAA decreased from 17.97, 40.97 and 27.63 respectively to 7.48, 14.44 and 8.55 respectively. The mean dist 1-2 decreased from 18.37mm to 13.99mm. The mean FFBW & FFSTW decreased from 96.87mm & 107.69mm to 86.27mm & 98.79mm respectively. The mean MFBW & MFSTW decreased from 79.00mm & 95.17mm to 73.17mm & 90.97mm< br /> For MIBS: IMA, HVA & DMAA decreased from 15.79, 31.98 and 16.01 respectively to 4.75, 8.19 and 4.20 respectively. Mean proximal IMA increased to 24.01. The mean dist 1-2 increased from 17.62mm to 21.71mm. The mean FFBW & FFSTW decreased from 94.88mm & 105.47mm to 87.99mm & 102.19mm respectively. The mean MFBW & MFSTW however increased from 78.47mm & 95.00mm to 82.23mm & 96.18mm.

Conclusion: Both MIBS and the MLP reduce measures of forefoot bony & soft-tissue width. However, MIBS was found to increase measures of proximal/midfoot bony & soft-tissue width while the MLP reliably reduced these variables.