Anatomical Study Of The Proximal Femoral Canal For Designing Total Hip Component

Objective: Total hip prostheses has become an accepted part of the orthopedics armamentarium because it provides an excellent pain relief and function in clinic practice, but the complications are obviously increased than ever before. The one main cause of the complications is that the femoral component did not fit the supporting bone cavity. How to avoid complications and to design total hip component is a more important problem in our country. The purposes of this article are to study the morphological of the proximal femur canal for designing total hip component.Material and Methods: One hundred and sixty femora were obtained from the department of anatomy of Chengde Medical College and the General Hospital of PLA. Specimens that showed evidence of osseous pathology, previous fractures or the presence of defect were excluded from the study. After labeled for identification and records each specimen was taken the anteroposterior, lateral, inner oblique at 45 and outer oblique at 45. Standard periosteal (extra cortical) and endosteal (intra cortical) dimensions were determined for each femur through direct measurement of each roentgenogram. The magnification rate for each specimen was calculated according the magnification for the steal bead of 3.14mm in diameter. To enable comparison of dimensions of bones of different overall size standardized horizontal and vertical reference axes were established using the geometric center of the lesser trochanter and the bisect axis of the medullary canal at the isthmus. Mean and standard deviation were calculated for each dimension of the population of femora by using SPSS (Statistical Package for Social Sciences), correlations between pairs of dimensions also were examined and confidence intervals calculated for estimation of each geometric parameter. Average dimension for all of the femora examined in the study were obtained.The transactional specimen were made in 5 femur at the level of 20mm above thecenter of lesser trochanter, the center of lesser trochanter, 20mm below the center of lesser trochanter, the proximal border of isthmus, the isthmus, the distal border of isthmus, the morphological characterize of the femur were observed on each sectional specimen (sample).Results: Most of these parameters approximated a Gaussian distribution (normal bell-shaped curve). Scatter plots of the femoral data demonstrated that substantial variability was present in every instance. Pair wise correlation of the geometric parameters showed that all dimensions were significantly associated, the statistical significance of these correlations indicated that the variation of the parameters were not purely random but not that the relationship between two variables was useful in the predictive sense.In this study the correlation coefficients varied from 0.239 to 0.802 in most instances, strong correlations were present (r>0.5) between pairs of periosteal dimensions. Stronger correlations were noted between variables describing the width of the canal in the vicinity of the lesser trochanter. The relationship is suggesting between the internal and external profiles of the femoral canal through the pairs of periosteal and endosteal dimensions.Based upon the measurement and the calculated, the femoral head offset, the femoral head diameter and the femoral head position was 34.0+5.9 mm, 42.6+3.3 mm. 47.3+5.9 mm respectively, the width at the point 20mm above the lesser trochanter, at the center of the lesser trochanter, at the point 20mm below that was 40.2+4.5 mm, 23.4+3.6 mm, 16.8+2.8 mm respectively; the mediolateral isthmus width and the extra cortical width at this level was 10.0+2.6mm, 24.0+2.6 mm respectively, the proximal border of isthmus and the distal border of it was 68.5+12.1 mm, 144.4+17.5 mm respectively, the neck-shaft angle and the anteversion angle was 128.4 +7.0 ; 9.4 +6.6 respectively.Conclusion: The availability of basic geometric data describing the proximal femur in the paper allows guidelines to be developed for the functional dimensions of femoral compo...