Axial alignment of the lower extremity in Chinese adults

Background: The restoration of normal axial alignment of the lower extremit y is important to surgeons who perform reconstructive surgery of the knee. However, data on the normal alignment of the lower extremity in Chinese adu lts are not available. Methods: The axial alignment of the lower extremity in twenty-five adult ma le and twenty-five adult female volunteers of southern Chinese origin was m easured on weight-bearing radiographs of the entire lower limb. The mean ag e was twenty-four years for the male volunteers and twenty-three years for the female volunteers. The results were compared,vith those of two similar studies of white volunteers in the United States. Results: The medial inclination of the tibial plateau in the Chinese subjec ts (mean and standard deviation, 5.4 +/- 2.5 degrees for women and 4.9 +/- 2.3 degrees for men) was greater than the commonly reported 3 degrees. The extremities of the Chinese women were found to have a mean of 2.2 +/- 2.5 d egrees of varus alignment, and those of the Chinese men had a mean of 2.2 /- 2.7 degrees of varus alignment, Conclusions: Compared with the white subjects described in the studies by M oreland ct al, and Hsu et al., the Chinese subjects had significantly large r medial inclination of the knee joint (knee-joint obliquity) (p < 0.005) a nd the female Chinese subjects had significantly more varus alignment of th e lower extremity (p < 0.025), Clinical Relevance: Five degrees of external rotation of the femoral compon ent, instead of the commonly reported 3 degrees, may be required to obtain a rectangular flexion gap in total knee arthroplasty in Chinese patients. T he racial difference in the knee-joint obliquity may contribute to the raci al difference in the ratio of knee osteoarthritis to hip osteoarthritis. Ad ditional studies are necessary to confirm this relationship.