Gross T S, Bunch R P
Converse Biomechanics Laboratory, North Reading, Massachusetts.
Am J Sports Med. 1989 Sep-Oct;17(5):669-74. doi: 10.1177/036354658901700514.
A model of metatarsal mechanics has been proposed as a link between the high incidence of second and third metatarsal stress fractures and the large stresses measured beneath the second and third metatarsal heads during distance running. Eight discrete piezoelectric vertical stress transducers were used to record the forefoot stresses of 21 male distance runners. Based upon load bearing area estimates derived from footprints, plantar forces were estimated. Highest force was estimated beneath the second and first metatarsal head (341.1 N and 279.1 N, respectively). Considering the toe as a hinged cantilever and the metatarsal as a proximally attached rigid cantilever allowed estimation of metatarsal midshaft bending strain, shear, and axial forces. Bending strain was estimated to be greatest in the second metatarsal (6662 mu epsilon), a value 6.9 times greater than estimated first metatarsal strain. Predicted third, fourth, and fifth metatarsal strains ranged between 4832 and 5241 mu epsilon. Shear force estimates were also greatest in the second metatarsal (203.0 N). Axial forces were highest in the first metatarsal (593.2 N) due to large hallux forces in relationship to the remaining toes. Although a first order model, these data highlight the structural demands placed upon the second metatarsal, a location of high metatarsal stress fracture incidence during distance running.
一种跖骨力学模型被提出来，作为第二和第三跖骨应力性骨折高发率与长跑过程中第二和第三跖骨头下方测得的巨大应力之间的联系。使用八个离散的压电垂直应力传感器记录了21名男性长跑运动员的前足应力。根据从脚印得出的承重面积估计值，估算了足底力。估计第二和第一跖骨头下方的力最高（分别为341.1牛和279.1牛）。将脚趾视为铰接悬臂，将跖骨视为近端附着的刚性悬臂，可以估算跖骨中轴的弯曲应变、剪切力和轴向力。估计第二跖骨的弯曲应变最大（6662微应变），该值比估计的第一跖骨应变大6.9倍。预测的第三、第四和第五跖骨应变在4832至5241微应变之间。剪切力估计值在第二跖骨中也最大（203.0牛）。由于与其余脚趾相比拇趾力较大，第一跖骨的轴向力最高（593.2牛）。尽管这是一个一阶模型，但这些数据突出了第二跖骨所承受的结构要求，而第二跖骨是长跑过程中跖骨应力性骨折高发的部位。
