# Sesamoid correction achieved during the learning curve for Scarf-Akin osteotomy without lateral soft-tissue release: a single-centre prospective observational study

## TL;DR

This study shows that Scarf-Akin osteotomy without lateral soft-tissue release can correct hallux valgus, with sesamoid correction improving as surgeons gain experience.

## Contribution

The study demonstrates that sesamoid correction improves during the learning curve of Scarf-Akin osteotomy without lateral soft-tissue release.

## Key findings

- Significant radiographic improvement in hallux valgus angle, intermetatarsal angle, and distal metatarsal articular angle was observed.
- Sesamoid position showed a strong positive correlation with the number of cases performed, indicating improvement during the learning curve.
- Only minor complications were reported, with one occurring in the early learning phase and one in the later phase.

## Abstract

Scarf-Akin osteotomy (with or without lateral soft-tissue release (LSTR)) is commonly performed to treat hallux valgus (HV). An insufficient correction of sesamoids can be a risk factor for early recurrence of the condition. We set out to determine 1) the radiographic correction achieved after Scarf-Akin osteotomy performed without LSTR and 2) the degree of correction of sesamoids obtained during the learning curve of the technique.

In this prospective single-centre study, the first 25 feet (25 patients, mean age 55.2 years, 14 left) undergone Scarf-Akin osteotomy without LSTR by a single foot and ankle orthopaedic consultant in his first year of activity were enrolled and followed-up at 1-year. On weightbearing standard pre-operative and 1-year follow-up radiographs two independent observers (senior residents) assessed and compared the hallux valgus angle (HVA), 1st and 2nd intermetatarsal Angle (IMA), distal metatarsal articular angle (DMAA) and tibial sesamoid position (SP, according to the Hardy and Clapham system). The inter and intraobserver reliability of measurements along with the correlation between the improvement achieved in different parameters and the number of cases performed were tested. Intra and post-operative complications were compared between the early (first 12) and late learning periods.

The inter and intraobserver agreement for the radiographic parameters investigated was excellent in all cases (ICC always > 0.92). A statistically significant improvement in mean HVA (from 36 ± 9.8 to 16.3 ± 2.8 degrees), mean IMA (from 14.5 ± 2.3 to 9.9 ± 1.5 degrees), mean DMAA (from 19.4 ± 4.4 to 11.4 ± 1.9 degrees) and median SP (from 4 (IQR, 3–6) to 2 (IQR, 1–2) points) was demonstrated in the cohort (p < 0.001 in all cases). There was a strong positive significant correlation between the progression of cases over time and the improvement achieved in terms of SP (R = 0.60, p = 0.003). Conversely, no significant correlation was demonstrated when comparing the improvement obtained in HVA, IMA and DMAA with the number of cases performed (p > 0.05 in all cases). One complication occurred during the first 12 cases (1 transfer metatarsalgia) and 1 during the last 13 (1 intra-operative fracture).

In this series, a satisfactory correction of HV after Scarf-Akin osteotomy was obtained without releasing lateral soft-tissues. Beginner surgeons should be aware that restoring sesamoid position may be more challenging as compared to correcting other angles during the first cases.

Level IV, prospective case series.