Radiographic Evaluation of Intermetatarsal Angle Correction Following First MTP Joint Arthrodesis for Severe Hallux Valgus.

BACKGROUND: Arthrodesis is a standard operative treatment for symptomatic arthritis of the first metatarsophalangeal (MTP) joint. Patients with degenerative joint disease (DJD), severe hallux valgus, and metatarsus primus varus may also require fusion of the first MTP joint. An important question in the latter group of patients is whether a proximal first metatarsal osteotomy is required, in addition to the first MTP joint fusion. Our hypothesis was that patients with severe hallux valgus and metatarsus primus varus, treated with first MTP joint arthrodesis alone, would have correction of the first-to-second intermetatarsal angle (1-2 IMA) and hallux valgus angle (HVA) to near population norms, without the addition of a proximal first metatarsal osteotomy.

METHODS: Preoperative and postoperative radiographs of 19 feet, in 17 patients, with preoperative IMA greater than 15 were analyzed. Weight-bearing radiographs were divided into pre- and postoperative cohorts. Three independent reviewers measured these radiographs and mean 1-2 IMA and HVA were calculated. Mean follow-up was 10 months.

RESULTS: The mean preoperative 1-2 IMA was 19.2 degrees (15.6-24.3). The mean preoperative HVA was 48.5 (36-56.6). The mean postoperative values for 1-2 IMA and HVA were 10.8 and 12.3 degrees, respectively. The mean change in IMA was 8.3 degrees and in the hallux valgus angle was 36.4 degrees. The differences between pre- and postoperative measurement for both angles were statistically significant (P < .001). Seven of 19 (37%) feet were corrected to an IMA of less than 9 degrees (normal), whereas in 15/19 feet the postoperative IMA was 12.3 degrees or less. The postoperative HVA was less than 15 degrees in 15/19 (79%) feet.

CONCLUSION: This pre- and postoperative radiographic analysis of patients with severe bunion deformity demonstrated that HVA and 1-2 IMA were acceptably corrected without the addition of a proximal first metatarsal osteotomy.

LEVEL OF EVIDENCE: Level III, retrospective comparative series.