Abstract
BackgroundThe ideal acetabular position for optimizing hip joint biomechanics in periacetabular osteotomy (PAO) remains unclear. We aimed to determine the relationship between acetabular correction in the coronal plane and joint contact pressure (CP) and identify morphological factors associated with residual abnormal CP after correction.MethodsUsing CT images from 44 patients with hip dysplasia, we performed three patterns of virtual PAOs on patient-specific 3D hip models; the acetabulum was rotated laterally to the lateral center-edge angles (LCEA) of 30°, 35°, and 40°. Finite-element analysis was used to calculate the CP of the acetabular cartilage during a single-leg stance.ResultsCoronal correction to the LCEA of 30° decreased the median maximum CP 0.5-fold compared to preoperatively (p < 0.001). Additional correction to the LCEA of 40° further decreased CP in 15 hips (34%) but conversely increased CP in 29 hips (66%). The increase in CP was associated with greater preoperative extrusion index (p = 0.030) and roundness index (p = 0.038). Overall, virtual PAO failed to normalize CP in 11 hips (25%), and a small anterior wall index (p = 0.049) and a large roundness index (p = 0.003) were associated with residual abnormal CP.ConclusionsThe degree of acetabular correction in the coronal plane where CP is minimized varied among patients. Coronal plane correction alone failed to normalize CP in 25% of patients in this study. In patients with an anterior acetabular deficiency (anterior wall index < 0.21) and an aspherical femoral head (roundness index > 53.2%), coronal plane correction alone may not normalize CP. Further studies are needed to clarify the effectiveness of multiplanar correction, including in the sagittal and axial planes, in optimizing the hip joint’s contact mechanics.
Highlights
The ideal acetabular position for optimizing hip joint biomechanics in periacetabular osteotomy (PAO) remains unclear
Previous finite element (FE) analysis studies have shown that acetabular correction in the coronal plane reduces joint contact pressure (CP) in cases of hip dysplasia [10, 11]; it remains unclear what the ideal position should be for each patient in order to optimize the contact mechanics of dysplastic hips
As the lateral center-edge angle (LCEA) was increased to 35° and 40°, the mean contact area further increased while the median maximum CP was comparable between the three virtual PAOs
Summary
The ideal acetabular position for optimizing hip joint biomechanics in periacetabular osteotomy (PAO) remains unclear. The 3D morphology of the hip joint substantially varies among candidates for PAO [12, 13], and clinical studies have shown that preoperative severe acetabular dysplasia [14] and aspherical femoral heads that lead to joint incongruity [15, 16] compromise joint survivorship following PAO. To date, it is not fully understood how preoperative hip morphology influences joint CP after coronal plane correction. We performed virtual PAO using patient-specific FE models in the standing pelvic position as a reference to determine the relationship between the amount of acetabular correction in the coronal plane and joint CP and identify radiographic factors associated with residual abnormal joint CP after correction
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