Foot function after fusion of the first metatarsophalangeal joint.

Background: We measured with a validated score the operative outcome in patients without concomitant foot surgery who underwent fusion of the first metatarsophalangeal (MTP) joint for hallux rigidus (HR) and hallux valgus (HV). We also examined whether there is a correlation between foot function and hallux position to try to formulate an optimum fusion angle.

Methods: Between 2002 and 2005, a consecutive series of 62 patients underwent crossed screw fusion of the first MTP joint (27 HR and 35 HV) without concomitant surgery of the same or contralateral foot or had previous surgery of the same foot. Foot function was measured by the Dutch Foot Function Index (FFI) pre- and postoperatively. Hallux valgus and dorsiflexion angles were measured on standing radiographs before operation and at followup.

Results: Postoperatively the median hallux valgus angle was 14 (range, -2 to 33) degrees and the median dorsiflexion angle was 23 (range, 7 to 45) degrees. The median FFI score improved from 38 (range, 0 to 80) to 8 (range, 0 to 59) (p < 0.001). The FFI score was not different between the HV and HR groups. There was no correlation between postoperative foot function, dorsiflexion angles and hallux valgus angles.

Conclusions: Fusion of the first MTP joint in HR and HV results in improved function according to the validated FFI. There was no significant correlation between foot function and hallux position. This could be due to the fact that the desired position of the hallux was most often achieved.