Abstract
Aim When first metatarsophalangeal (MTP) joint fusion is performed in the presence of a high first intermeta-tarsal angle (IMA), an important question to arise is whether the first metatarsal varus will correct with MTP fusion alone or whether an additional basal osteotomy is necessary. We compared the pre-operative IMAs to the post-operative angles to answer this question.
Method Twenty patients had a first MTP fusion for severe hallux valgus deformity performed by the senior author over a 2-year period. All were female. Mean age was 54.2 years (range 42–78). Seven patients had rheumatoid arthritis. Their IMAs were retrospectively measured on weight bearing X-rays taken pre-operatively and 6 weeks post-operatively. They were recalled for an additional measurement at a mean of 13.72 months (range 6–30).
Results Pre-operatively the mean hallux valgus angle was 46.55 degrees and the mean IMA was 16.65 degrees (range 12–26). The mean 6 week post-operative IMA was 10.35 degrees (range 6–15) with a mean improvement of 6.3 degrees (range 0–12). The mean IMA at final follow-up was 8.67 degrees (range 5–12). The mean final improvement was 8.22 degrees (range 4–14). In eight patients with a pre-operative IMA of 15 degrees or less the mean improvement was 6.13 degrees. In 10 patients with an pre-operative IMA of 16 degrees or more, the mean improvement was 9.9 degrees.
Significance First MTP joint fusion in hallux valgus deformity permanently reduces the IMA. As the pre-operative IMA increases from moderate to severe, there is a significant increase in post-operative correction. An additional basal osteotomy is not indicated.
Correspondence should be addressed to BOFSS, c/o Wrightington Wigan and Leigh NHS Trust, Hall Lane, Appley Bridge, Wigan, Lancashire WN7 9EP.
