The biomechanical influences of cystic degeneration in different locations within femoral head
- VernacularTitle:股骨头不同区域囊变对力学承载的影响
- Author:
Dewei ZHAO
;
Dachuan XU
;
Xu CUI
- Publication Type:Journal Article
- Keywords:
Femur head necrosis;
Biomechanics;
Image processing, computer-assisted
- From:
Chinese Journal of Orthopaedics
1999;0(04):-
- CountryChina
- Language:Chinese
-
Abstract:
Objective To explore the biomechanical influences of cystic degeneration in different locations on femoral head and guide the appropriated surgical treatment to preserve the femoral head. Methods First scanning a upper femur specimen with spinal CT, dealing the two-dimensional image with Efilm software, identifying the outline of the femoral head by range estimation, inputting coordinate value of the femur into the computer to build up three-dimensional finite element model of the upper femur by Ansys-5.7 software, then simulating necrosis and cystic degeneration of 1 cm diameter by analogue computer, at last putting three kinds of pressure on the femoral head respectively to analyse the stress distribution and the stress/strength ratio and predict the collapse of the femoral head. Results The tension concentration was obvious when the necrosis and cystic degeneration was beneath the loading area or medial or lateral to the loading area in the femoral head, the stress/strength ratio of the cancellous bone beneath the articular surface was high which tends to cause collapse of the femoral head. When the necrosis and cystic degeneration located in the inferior parts of the femoral head, the strain concentration was not obvious and the stress/strength ratio of the cancellous bone beneath the articular surface was normal and the femoral head had little danger of collapse. When the focus located in the anterior or posterior part of the femoral head, its upper edge displayed tension concentration but not obvious and the stress/strength ratio of the cancellous bone beneath the articular surface was lower than normal and the danger of collapse was little. Conclusion When the necrosis and cystic degeneration is beneath the loading area or medial or lateral to the loading area in the femoral head, the focus should be cleared thoroughly and the vascularised bone flap should be implanted ideally with abutment against the subchondral plate to prevent the collapse of the femoral head. If the necrotic range is large involved the loading area and its medial or lateral sides, the vascularised bone flap should be implanted beneath the loading area.
