Intermetatarsal angular change following fusion of the first metatarsophalangeal joint.

Background: Arthrodesis of the first metatarsophalangeal (MTP) joint with a low profile fixed angle plate allows for a consistent resultant hallux valgus angle. There is no clear consensus on whether a separate corrective osteotomy of the first metatarsal should be performed in addition to the first metatarsophalangeal joint fusion in patients with an increased intermetatarsal angle. We quantified the amount of correction of the intermetatarsal angle as well as the position of the tibial sesamoid in this group of patients following fusion of the first MTP joint.

Materials And Methods: A consecutive cohort of 69 feet (13 bilateral) who underwent a standard primary fusion of the first metatarsophalangeal joint using a dorsal approach between May 2006 and January 2008 were reviewed. Radiological measurements were taken from 6-week postoperative weightbearing radiographs and included the hallux valgus angle, intermetatarsal angle as well as the position of the tibial sesamoid in accordance to the American Orthopaedic Foot and Ankle Society guidelines.

Results: Postoperatively, there was an improvement in the hallux valgus angle from 33.0 degrees to 10.4 degrees (p < 0.001). The mean intermetatarsal angle also improved from 13.1 degrees preoperatively to 8.6 postoperatively (p < 0.001). The position of the tibial sesamoid generally improved by at least one grade (Spearman's r = 0.74). There was a strong correlation (r = 0.77, p < 0.001) between the preoperative intermetatarsal angle and the postoperative intermetatarsal angle.

Conclusion: Both the intermetatarsal angle and position of the tibial sesamoid reliably improved following arthrodesis of the first MTP joint, negating the need for a separate osteotomy of the first metatarsal.