open access

https://hdl.handle.net/2115/75385

Effects of femoral bone defect morphology on initial polished tapered stem stability in massive defect model: a biomechanical study

英語

Initial stem stability

2019-08-01

BioMed Central

BMC musculoskeletal disorders

20

355

BackgroundGood 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.MethodsInitial stability of the Exeter stem was investigated in a composite bone model using three medial bone defect morphologies: Long (length 5cmxwidth 2cm), Short (2.5cmx2cm), Square (3.2cmx3.2cm), Square with mesh (3.2cmx3.2cm defect covered with metal mesh), and with no defect as control. Specimens (5 per group) were axially loaded and internally rotated up to 20 degrees or to failure. Strain distributions of the femora were measured using a strain gauge.ResultsAll 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 (4.40.3Nm/deg.) and Square groups (4.3 +/- 0.3Nm/deg.) was significantly smaller than in the Control group (4.8 +/- 0.3Nm/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.Conclusions 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 3cm or more in width.

学術雑誌論文

Version of Record

Creative Commons Attribution 4.0 International

1471-2474

AA12035278