Pseudobunion: A new unfortunate result after new minimally invasive bunion surgery. A retrospective radiographic review and case series of 17 feet

Abstract

Minimally invasive bunion surgery (MIBS) techniques may produce a new painful, bunion-like complication caused by the residual medial ledge of bone. This “pseudobunion” has not been previously studied and the focus was on patients requiring revision surgery for hardware removal and/or metatarsal exostectomy.

A 7-year case review was performed between January 2018 to December 2024 and we identified 17 feet (16 patients) with pseudobunion requiring surgery. Data collected included age, sex, laterality, intermetatarsal angle (IMA), hallux valgus angle (HVA), bunion severity, first metatarsal regeneration (FMR) type and number of screws used during the index surgery. Radiographic evaluation included a newly defined metatarsal ledge resection angle (MLRA).

The mean age was 46.6 years and 100 % were females. One patient had bilateral pseudobunion. The mean interval between the index surgery and revision was 366.7 ± 132.2 days. A 2-screw construct was used in 10 feet (58.8 %) and a 1-screw construct in 7 feet (41.2 %). Index MIBS had a mean preoperative IMA of 17.1° ± 2.4° and postoperative 4.3° ± 1.4° (p < 0.0001), and mean preoperative HVA of 33.5° ± 8.4° and postoperative of 4.3° ± 4.3° (p < 0.0001). Pseudobunion did not occur in mild bunions. At revision, the mean MLRA improved from 56.0° ± 15.9° at the index to 24.4° ± 3.2° post-revision, reaching statistical significance (p < 0.0001).

Two-screw constructs were associated with a higher incidence of Type I FMR (80 %), whereas one-screw constructs demonstrated predominantly Type II/III FMR (85.7 %), demonstrating a statistically significant association between number of screws and FMR healing type (p = 0.015). Year-over-year analysis, demonstrated a statistically significant downward trend in pseudobunion revisions (R² = 0.86, p = 0.008). While the relative distribution of number of screws did not significantly differ by year (p = 0.176), no pseudobunion revisions with 1-screw constructs have occurred since 2021, coinciding with the development of a 1-screw construct and resection technique allowing for full ledge removal.

Pseudobunion is a new complication that can be effectively addressed with revision surgery. However, it may be preventable during the index bunion procedure through careful selection MIBS generation, screw construct choice and adequately resecting the medial ledge.