改良Mitchell手术治疗外翻

Treatment of hallux valgus with modified Mitchell operation

[目的]观察改良Mitchell手术治疗拇外翻的疗效。[方法]自2000年4月～2003年10月对18例28足拇外翻患者行改良Mitchell手术。术前摄负重X线片，测量拇外翻角（hallux valgus angle，HVA）平均为30．5°，第1、2跖骨间角（Intermetatarso-phalangeal angle，IMA）13．5°。本术式与传统Mitchell手术不同的是在第1跖骨远端只行一次横行截骨，不留外侧棘，根据IMA的大小决定截骨远端外移的多少，再向跖侧移位2～3mm，用可吸收螺钉固定。[结果]随访28足，随访时间为10～32个月，优24足，良3足，差1足，优良率为92．9％。术后负重X线片测量HVA 15．5°，平均改善15°；IMA平均为8．5°，平均改善5°。[结论]改良Mitchell手术可矫正第1跖骨内翻，更重要的在于矫正畸形而不破坏拇趾的生物力学作用，第1跖骨头的跖侧移位，重建了足横弓，恢复了拇趾的负重功能。

[ Objective] To observe the effect of treating hallux valgus with modified Mitchell operation. [ Method] A total of 18 cases （ 28 feet ） of hallux valgus were treated with modified Mitchell operation from Apr. 2000 to Oct. 2003. The average preoperative hallux valgus angle （HVA） was 30. 5 according to the X-ray images, while the average intermetatarso-phalangeal angle （IMA） was 13.5. The difference between the modified Mitchell operation and normal one was that only one transverse osteotomy need to be carried out in the distal metatarsal without lateral ridge left. The distal position of osteotomy was extended according to the sum of IMA and then moved to the metatarso side by 2 ～ 3 mm. Absorbable screws were used for fixation. [ Result] All 28 feet were followed up for 10 ～ 32 months. It showed excellent result in 24 feet, good in 3, and bad in 1, with the total satisfactory rate of 92. 9%. According to the postoperative weight-loading X-ray checking result, the average HVA was 15.5, with an average improving of 15 ; the average IMA was 8. 5, with an average improving of 5. [ Conclusion] The modified Mitchell operation can correct the metatarso-varus without destroying the biomechanical status. The loading function of great toe could be resumed by the removing of the first metatarso head.