Does the intermetatarsal angle play a role in first metatarsophalangeal joint arthrodesis rate and time to union?

BACKGROUND

A first metatarsophalangeal joint (1st MTPJ) arthrodesis is a reliable procedure for treating osteoarthritis with severe hallux valgus deformities. However, the effect of preoperative first-second intermetatarsal (IM) angle deformity on union rates and time to union remains unclear.

METHODS

A retrospective review was conducted on patients that underwent a 1st MTPJ arthrodesis for correction of osteoarthritis and hallux valgus deformity from 2010 to 2020 utilizing a dorsal locking plate and interfragmentary lag screw fixation technique. All procedures were performed at a single reconstructive foot and ankle fellowship program. Patients were stratified into three groups based on preoperative IM angle: mild (≤11°), moderate (11.1-14.9°), and severe (≥15°). Exclusion criteria included: prior first ray surgery, other hardware techniques differing from dorsal locking plate and interfragmentary lag screw method, revision cases, and missing preoperative imaging. The Foot Union Scoring Evaluation Tool (FUSET) was utilized at standard postoperative intervals to define union of the 1st MTPJ arthrodesis.

RESULTS

A total of 58 patients met inclusion criteria. Fusion was achieved in one hundred percent of the cases across all IM angle groups. There were no cases of nonunion or hardware failure. Average time to radiographic union was similar between groups. There was no statistically significant difference in FUSET scores observed at any point during the follow-up interval. Additionally, smoking history, diabetes, and vitamin D supplementation had no apparent impact on time to fusion.

CONCLUSIONS

The preoperative first-second IM angle did not influence fusion rate or time to union following 1st MTPJ arthrodesis for osteoarthritis and hallux valgus correction using a dorsal locking plate and interfragmentary lag screw construct. Given the 100 % union rate, this fixation technique offers reliable results regardless of the severity of the IM angle.