Abstract
Objective
The purpose of this study was to compare the proximal femoral morphology between normal Chinese and Caucasian populations by 3D analysis derived from CT data.
Materials and Methods
141 anonymous Chinese femoral CT scans (71 male and 70 female) with mean age of 60.1years (range 20–93) and 508 anonymous Caucasian left femoral CT scans (with mean age of 64.8years (range 20–93). The CT scans were segmented and converted to virtual bones using custom CT analytical software. (SOMA™ V.4.0) Femoral Head Offset (FHO) and Femoral Head Position (FHP) were measured from head center to proximal canal central axis and to calcar or 20mm above Lesser Trochanter (LT) respectively. The Femoral neck Anteversion (FA) and Caput-Collum-Diaphyseal (CCD) angles were also measured. The Medial Lateral Widths(MLWn) of femoral canal were measured at 0, -10, LT, -30, -40, -60, -70 and -100mm levels from calcar. Anterior Posterior Widths (APWn) were measured at 0, -60 and -100mm levels. The Flare Index (FI) was derived from the ratio of widths at 0 and -60mmor FI=W0/W−60. All measurements were performed in the same settings for both populations. The comparison was analyzed by Student T test. P<0.05 was considered significant.
Results
The average FHO and FHP of Chinese were 38.4mm and 25.2mm and were both shorter than 42.1mm and 29.7mm of Caucasian's, P=2.3E-15 and P=1.7E-10. (Figure 1) CCD angle was 130.3° comparing to 127.7° of Caucasian P=1.5E-05. Chinese FA angle was 15.6° and Caucasian's was 14.7°, P=0.31. The average MLW1-8 were 43.1, 34.6, 28.5, 23.8, 20.6, 17, 16.2 and 14.4mm for Chinese and 43.7, 35.0, 28.7, 24.0, 20.6, 16.7, 15.7 and 13.5mm for Caucasian. P=9.4E-02, .32, .47, .50, .93, .20, .02 and 1.7E-05 respectively. (Figure 2) The average APW1-3 were 35.9, 15.5 and 13.7mm for Chinese and 43.7, 15.2 and 12.5mm for Caucasian. P=4E-62, 0.11 and 7.4E-10. (Figure 3) The total medial/lateral and medial/center FI were 2.5 and 2.8 for Chinese, 2.6 and 2.9 for Caucasian. P=.004 and 4.5E-06. The total anterior/posterior and anterior/center FI were 2.3 and 2.6 for Chinese, 2.9 and 2.5 for Caucasian. P=5.3E-61 and 8.5E-04.
Conclusion and Discussion
Chinese had significantly lower FHO, FHP, APWcalcar, FImedial, M-L and FIA-P; significantly higher CCD angle and MLWisthmus, APWisthmus and FIanterior than that of Caucasian population. There were no significant differences in FA and MLW from 10mm above to 50mm bellow LT. The average reduction of 3.7mm in FHO and 4.5mm in FHP for Chinese suggests a necessary adjustment of femoral implant neck length designed for Caucasian population. Due to the findings of the similarity in MLW and dissimilarity in APW, the study suggested the M-L fitting stem will fit well for both populations.
