Department of Orthopaedic Surgery, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Kita 15, Nishi 7, Kita-ku, Sapporo, 060-8638, Japan.
Department of Biostatistics, Graduate School of Medicine, Hokkaido University, Sapporo, Japan.
BMC Musculoskelet Disord. 2019 Aug 1;20(1):355. doi: 10.1186/s12891-019-2716-8.
Good outcomes have been reported in revision total hip replacement with massive segmental defects using impaction bone grafting with circumferential metal meshes. However, the morphology of defects that require a mesh is poorly defined. The purpose of this study was to evaluate the effects of a variety of segmental defects on load transmission to the proximal femur under both axial and rotational loads.
Initial stability of the Exeter stem was investigated in a composite bone model using three medial bone defect morphologies: Long (length 5 cm × width 2 cm), Short (2.5 cm × 2 cm), Square (3.2 cm × 3.2 cm), Square with mesh (3.2 cm × 3.2 cm defect covered with metal mesh), and with no defect as control. Specimens (5 per group) were axially loaded and internally rotated up to 20° or to failure. Strain distributions of the femora were measured using a strain gauge.
All Square group specimens failed while rotation was increasing. In the other four groups, failure was not observed in any specimens. Mean torsional stiffness in the Long (4.4 ± 0.3 Nm/deg.) and Square groups (4.3 ± 0.3 Nm/deg.) was significantly smaller than in the Control group (4.8 ± 0.3 Nm/deg.). In the medio-cranial region, the magnitude of the maximum principal strain in the Square group (1176.4 ± 100.9) was significantly the largest (Control, 373.2 ± 129.5, p < 0.001; Long, 883.7 ± 153.3, p = 0.027; Short, 434.5 ± 196.8, p < 0.001; Square with mesh, 256.9 ± 100.8, p < 0.001). Torsional stiffness, and both maximum and minimum principal strains in the Short group showed no difference compared to the Control group in any region.
Bone defect morphology greatly affected initial stem stability and load transmission. If defect morphology is not wide and the distal end is above the lower end of the lesser trochanter, it may be acceptable to fill the bone defect region with bone cement. However, this procedure is not acceptable for defects extending distally below the lower end of the lesser trochanter or defects 3 cm or more in width.
在使用环形金属网片进行打压植骨治疗严重节段性骨缺损的翻修全髋关节置换中，已有良好的结果报告。然而，需要使用网片的缺损形态定义较差。本研究的目的是评估在轴向和旋转负载下，各种节段性缺损对股骨近端的负载传递的影响。
在复合骨模型中，使用三种内侧骨缺损形态研究 Exeter 柄的初始稳定性：长（长度 5cm×宽度 2cm）、短（2.5cm×2cm）、方形（3.2cm×3.2cm）、方形加网（3.2cm×3.2cm 缺损覆盖金属网）和无缺损作为对照。（每组 5 个标本）进行轴向加载和内部旋转，直到 20°或失效。使用应变计测量股骨的应变分布。
所有方形组的标本在旋转增加时都失效了。在其他四组中，没有观察到任何标本失效。长（4.4±0.3Nm/deg.）和方形组（4.3±0.3Nm/deg.）的平均扭转刚度显著小于对照组（4.8±0.3Nm/deg.）。在中颅区，方形组的最大主应变值（1176.4±100.9）最大（对照组为 373.2±129.5，p<0.001；长组为 883.7±153.3，p=0.027；短组为 434.5±196.8，p<0.001；方形加网组为 256.9±100.8，p<0.001）。在任何区域，短组的扭转刚度以及最大和最小主应变与对照组均无差异。
骨缺损形态对初始柄稳定性和负载传递有很大影响。如果缺损形态不宽，且远端位于小转子下端以上，则用骨水泥填充骨缺损区域可能是可以接受的。然而，对于延伸到小转子下端以下或宽度为 3cm 或以上的缺损，这种方法是不可接受的。
