两种第二趾切取游离移植对供足足底应力影响的生物力学研究

Biomechanical effects of the second plantar toe transfer on the plantar stresses of the donor foot

目的 探讨第2足趾切取游离移植对供足足底应力的影响.方法 取6具正常成人新鲜尸体足标本,根据不同状态分3组：完整组（A组）、第2趾截除（保留跖骨头）组（B组）及带部分跖骨的第2趾截除（跖骨远l/3处）组（C组）.应用电子万能试验机以2 mm/min的速度从胫骨远端施加轴向压载,加载载荷分别为0、600、1200 N.通过F-Scan足底压力测量系统检测足底应力变化,并对数据进行统计学分析.结果 足底应力随轴向压载的增加而增大.A组（足母）指及5个跖骨头的峰值压强以第2跖骨头最大,600 N垂直载荷时为（37.33±7.34）kPa,1200 N垂直载荷时为（112.33±10.33）kPa.同一载荷下,A组与B组的（足母）指及5个跖骨头的峰值压强差异均无统计学意义（P〉0.05）.同一载荷下,A组、B组分别与C组比较,（足母）指及5个跖骨头的峰值压强差异均有统计学意义（P〈0.05）.结论 第2跖骨的完整对足底应力正常分布及维持足弓具有重要意义.保留跖骨头的第2趾切取对供足足底应力分布影响较小,带部分跖骨的第2趾切取可导致供足足底应力的异常分配.

Objective To evaluate the biomechanical effects of the second plantar toe transfer on the plantar stresses of the donor foot. Methods Six fresh-frozen cadaveric specimens of foot were randomized into 3 experimental groups： （1）intact, （2）undergoing osteotomy of the second toe with the second metatarsal head remained, （3）undergoing osteotomy of the second toe with dissection of the second metatarsal head from the distal 1/3. Vertical downward axial loads of 0, 600 N and 1200 N were applied to the distal tibia at a 2mm/min velocity. Plantar stresses were measured by the F-Scan plantar pressure measurement system and analyzed statistically. Results The plantar stresses increased gradually with the increase of axial loading.The peak stress was observed at the second metatarsal head in the intact group. There were no significant differences in the plantar stresses of the 5 metatarsal heads between group A and group B （ P〉0.05）. There were significant differences in the plantar stress of the 5 metatarsal heads among the 3 groups under the axial loads of 600 N and 1200 N （P〈0.05）. Conclusions The second metatarsal bone plays an important role in supporting a normal distribution of the plantar stresses and foot arch. Osteotomy of the second toe but with the second metatarsal head remained may have insignificant effects on the plantar stresses. Osteotomy of the second toe from the distal 1/3 of the second metatarsal bone may result in abnormal distribution of the plantar stresses.