Cook S D, Lavernia C J, Burke S W, Skinner H B, Haddad R J
J Pediatr Orthop. 1983 Sep;3(4):449-54. doi: 10.1097/01241398-198309000-00006.
To elucidate the cause of tibia vara, finite element analysis of the proximal tibia was used to investigate the stresses occurring in the physeal plate during one-legged stance in 2- and 5-year-old children. A modification of the method of Kettlekamp and Chao was used to assign forces to the medial and lateral plateaus and lateral ligament. Stresses were calculated in the physeal plate for the two age groups as a function of degree of varus and body weight. Our results show that increasing varus resulted in increasing compressive stress in the medial tibial physis to a level seven times normal at 30 degrees of varus. Further, tensile stresses determined in the lateral tibial physis were increased above normal. Changes were more marked in the obese child and in the 5 year old. Using the data from Strobino et al. it appears that in the 2 year old 20 degrees of varus resulted in forces sufficient to retard growth. In the 5 year old, however, 10 degrees of varus resulted in borderline forces in a child of normal weight, but forces exceeding those necessary to retard physeal growth were calculated in the model of the obese child. Our data are consistent with the hypothesis that Blount's disease is primarily the result of the proximal tibial epiphysis responding to physical phenomena.
为阐明胫骨内翻的病因，采用胫骨近端有限元分析来研究2岁和5岁儿童单腿站立时生长板中产生的应力。采用对Kettlekamp和Chao方法的一种改进，将力分配到内侧和外侧平台以及外侧韧带。计算了两个年龄组生长板中的应力，作为内翻程度和体重的函数。我们的结果表明，内翻增加导致胫骨内侧生长板的压应力增加，在30度内翻时达到正常水平的7倍。此外，胫骨外侧生长板中确定的拉应力高于正常水平。肥胖儿童和5岁儿童的变化更为明显。根据Strobino等人的数据，在2岁儿童中，20度内翻产生的力足以阻碍生长。然而，在5岁儿童中，10度内翻在正常体重儿童中产生临界力，但在肥胖儿童模型中计算出的力超过了阻碍生长板生长所需的力。我们的数据与Blount病主要是胫骨近端骨骺对物理现象作出反应的结果这一假设一致。
