Experimental study on the effect of acetabular coverage on subchondral bone microstructure of femoral head
Objective:Hip parameters such as acetabular coverage could reflect the stress distribution of femoral head.To study the relationship between hip parameters such as acetabular coverage and subchondral bone volume frac-tion(BV/TV)of femoral head by using micro-computed tomography(Micro-CT)after hip joint replacement in pa-tients with femoral neck fracture(subcephalic type).By further exploring the changes of subchondral bone microstruc-ture induced by local biomechanical changes,so as to provide theoretical basis for preoperative planning and design of biological prostheses.Methods:Thirty cases of femoral head specimens after hip replacement due to femoral neck frac-ture were collected.Preoperative conventional CT plain scan and anteroposterior pelvic radiographs were taken.Hip pa-rameters such as CE angle,sharp angle,neck trunk angle and acetabular inclination angle were measured on anteropos-terior pelvic radiographs,and three-dimensional reconstruction was performed on anteroposterior CT scan.ImageJ,the official software of the National Institutes of Health,was used to measure acetabular coverage and calculate acetabular coverage.Subchondral cylindrical cancellous bone columns on the tension side and the stress side were selected with the concave of femoral head as the location marker.The prepared tissue specimens were sent to the Shanghai Sixth People's Hospital for Micro-CT scanning,reconstruction,and analysis of parameters such as ROI bone volume fraction(BV/TV).The relationship between hip joint parameters and subchondral bone microstructure parameters was analyzed by univariate analysis and multivariate linear regression analysis.Results:Subchondral bone volume fraction(BV/TV)on the stress side of the femoral head was significantly larger than that on the tension side,and the ratio of subchondral bone volume fraction on the stress side of the femoral head to the tension side was significantly correlated with acetabulum cov-erage and BMI.The greater the acetabulum coverage and BMI,the greater the ratio of subchondral bone volume fraction on the stress side of the femoral head to the tension side.Conclusion:The absolute change value of subchondral bone volume fraction of the femoral head is positively correlated with the coverage of the acetabulum.The disordered joint stress load caused by inadequate coverage of the femoral head may lead to a significant reduction in the volume of the bone trabeculae,which is harmful to the biomechanical properties and articular cartilage.Excessive BMI may lead to an increase in the local subchondral bone volume fraction on the stress side of the femoral head,which may cause subchon-dral bone sclerosis,it may further contribute to the loss of stress buffer of cartilage and aggravate cartilage damage.
Femoral headAcetabular coverageMicrostructure of boneMicro-CT
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