To evaluate postoperative results of modified Mitchell's osteotomy and its combination with oblique metatarsal osteotomy for the treatment of hallux valgus. A total of 93 feet of 53 patients (2 men and 51 women) with hallux valgus underwent modified Mitchell's osteotomy and were followed up for at least 5 years. Patients' age ranged from 17 to 83 years, and the duration of follow-up ranged from 5 years one month to 18 years 4 months. Modified Mitchell's osteotomy was performed on 53 feet in 31 patients (group A), whereas modified Mitchell's osteotomy augmented with oblique lesser metatarsal osteotomy was performed to the remaining 40 feet in 22 patients (group B). Postoperative results were assessed using a clinical assessment system developed by the Tokyo Medical University based on 5 categories: pain in the first metatarsophalangeal, deformity of the metatarsophalangeal, plantar callosity and/or metatarsalgia of lesser metatarsals, the use of commercially available shoes, and local inflammatory symptoms. Mean total score improved from 3.8 to 7.9 on a 10-point scale. Scores for 2 categories--plantar callosity and/or metatarsalgia and the use commercially available shoes--were significantly higher in group B at postoperative 5 years. Before surgery, at postoperative 3 weeks, and at postoperative 5 years, respectively, the mean hallux valgus angles were 34.2, 12.0, and 17.1 degrees; mean M1-M2 angles were 16.7, 7.4, and 8.7 degrees; mean M1-M5 angles were 34.9, 25.8, and 26.6 degrees; and mean sesamoid bone shifts were 8.7 mm, 4.3 mm, and 5.9 mm. Modified Mitchell's osteotomy shortens the length of the first metatarsal bone and thus relieves tension in soft tissues such as the adductor hallucis. Nonetheless, the procedure can induce metatarsophalangeal joint malalignment and metatarsalgia, and plantar callosity may develop or persist after surgery. Combining oblique metatarsal osteotomy of the lesser metatarsal bones is useful in patients with uneven metatarsal bone lengths and metatarsophalangeal joint malalignment.
