Fishkin Zair, Armstrong Douglas G, Shah Hardik, Patra Abani, Mihalko William M
Department of Orthopaedic Surgery, University at Buffalo, Buffalo, NY, and Department of Orthopaedics, Rainbow Babies and Children's Hospital, Cleveland, Ohio 44139, USA.
J Pediatr Orthop. 2006 May-Jun;26(3):291-4. doi: 10.1097/01.bpo.0000217730.39288.09.
The following finite element study was conducted to determine whether increased body weight, femoral retroversion, and varus hip loading could sufficiently raise physeal shear strains and stresses above the yield point and predispose an adolescent hip to a slip. A computer tomography scan of a 13-year-old child with slipped capital femoral epiphysis was used to generate a solid model of the proximal femur and physis. The model was parameterized using 3-dimensional software to generate three difference angles of femoral neck version-neutral, 15 degrees retroversion, and 15 degrees anteversion. Loads of 2.7 times body weight in a 46- and 86-kg child were applied to the proximal femur to model stance on one leg. In addition, the loading vector was reoriented at various degrees of varus to study the effect of varus loading on physis shear. The results demonstrated that physis stress, strain, and displacement increased with greater body weight, retroversion, and varus displacement of the loading vector. Physis shear strain in hips with a combination of varus loading and femoral neck retroversion exceeded the reported ultimate strain values for cartilaginous soft tissues. The finite element models suggest that in an overweight child, the combination of retroversion and varus hip load may be sufficient to increase physeal strains above the yield point and result in a slip.
进行了以下有限元研究，以确定体重增加、股骨后倾和髋内翻负荷是否能充分提高骺板剪切应变和应力，使其超过屈服点，并使青少年髋关节易于发生滑脱。使用一名13岁患有股骨头骨骺滑脱患儿的计算机断层扫描来生成近端股骨和骺板的实体模型。使用三维软件对模型进行参数化，以生成股骨颈不同角度——中立位、后倾15度和前倾15度。对一名46千克和一名86千克儿童的近端股骨施加相当于体重2.7倍的负荷，以模拟单腿站立。此外，将加载向量以不同程度的内翻重新定向，以研究内翻负荷对骺板剪切的影响。结果表明，骺板应力、应变和位移随着体重增加、后倾以及加载向量的内翻位移而增加。内翻负荷和股骨颈后倾相结合的髋关节的骺板剪切应变超过了报道的软骨软组织的极限应变值。有限元模型表明，在超重儿童中，后倾和髋内翻负荷的组合可能足以使骺板应变增加到超过屈服点并导致滑脱。
