| Summary: | 碩士 === 國立陽明大學 === 醫學工程研究所 === 93 === Abstract
The proximal femoral canal geometry is important, not only to the manufacturers in designing a femoral component, but also to the surgeons in selecting an optimal fit prosthesis. Canal shapes were also reported as a prognostic factor affecting the survivalship of a total hip prosthesis. According to Noble, the shapes of proximal femoral canals in normal subjects are remarkably variable and can be simply classified into three categories - stovepipe, normal and champagne-flute, according to the arbitrarily classification of their canal flare indices. Several factors can affect the shape of a proximal femur; they are age, race and developmental hip diseases. However, there are no reports on proximal femoral canal shapes of osteoarthritic, osteonecrotic, osteoporotic patients, who happened to be the largest groups in hip replacement surgery. The possible difference in canal shapes between the diseased hips and the normal subjects are also not studied. Hip prostheses are designed based on the assumption that the disease processes of these diagnoses do not change their femoral canal shapes.
Most femoral components are provided in a wide range of size in order to accommodate the wide variation of canal shape and diameter. However, the shapes of femoral stems are of limited choice in a particular design, despite the importance of stem-canal fit in a hip replacement surgery. Surgeons have to prepare the canal by reaming and broaching in order to achieve a good stem fit.
Therefore the purpose of the current study was to measure the canal flare indices of the diseased hips. It was designed to elucidate the possible difference in canal shapes among the osteoarthritic, osteonecrotic, and osteoporotic patients. Comparison between each group to a normal control (n group, 103 cases) was also performed. Stem-canal fitting was compared among the groups. The clinical effects of mismatch between the femoral components and femoral canals were lastly presented.
From January 1993 to December 1999, 369 cases were collected for the study to analyse the proximal femoral canal shapes in osteoarthritic (oa group, 69 cases), osteoporotic (fnf group, 101 cases) and osteonecrotic (on group, 199 cases) patients. Significant differences in canal flare index were found between the fnf group and the other three groups respectively; and also between the oa group and n group in an age-unmatched study. Difference was only seen between the fnf and n group after age-matched control. The results seemed to be explicable by age factor. Among the three diseased groups, stem-canal fit was not found to be different. Finally, the relationship between the clinical results and stem-canal fit was inconclusive due to small sample size.
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