Do Postoperative Hallux Angles Correlate With Outcome in MP1 Fusion? Our Experience With 71 Cases

To determine if the postoperative alignment of the hallux influences the final clinical outcome of hallux metatarsophalangeal joint (first MTPJ) arthrodesis.

A total of 71 consecutive cases (hallux rigidus) were studied in stages 3 and 4. They were operated through arthrodesis between 2008 and 2014. The follow-up mean was 7.3 years. The AOFAS (American Orthopaedic Foot and Ankle Society) test was performed preintervention and per annum. In radiology, both the hallux valgus angle and the dorsiflexion angle of the first MTPJ were studied. Furthermore, clinical outcomes were evaluated according to the type of implant used.

Preoperative AOFAS score was 27.5, rising to 91.3 after the intervention ( P < .01). The improvement test average was 63.6. There were 17 local complications (23%), 7 of them were considered to be major complications (9%), 6 of which needed reoperation (8.5%). The dorsiflexion angle postoperative mean was 21.7°. The hallux valgus angle postoperative mean was 10.9°. No correlations between both angles, and improved AOFAS score or complications ( P > .4 and P > .5, respectively), were found. Patients who had a dorsiflexion angle higher than 20° had greater improvement in the AOFAS score compared with those who had angles lower than 20° (64.5 vs 59.6 points). Nevertheless, this result was not statistically significant ( P = .059). No differences in AOFAS score improvement regarding arthrodesis plate ( P > .1) were found.

First MTPJ arthrodesis is a good alternative for patients in advanced hallux rigidus stages when conservative treatment fails. We could not confirm if a better postoperative alignment may influence in clinical outcomes. However, better results are obtained with dorsiflexion angle greater than 20° than with those with less than 20°. Likewise, any differences between the 2 arthrodesis plates have been able to confirm.

Level III: Retrospective cohort study.