Background: The restoration of normal axial
alignment of the lower extremity is important to surgeons who perform
reconstructive surgery of the knee. However, data on the normal
alignment of the lower extremity in Chinese adults are not available.
Methods: The axial alignment of the lower extremity
in twenty-five adult male and twenty-five adult female volunteers
of southern Chinese origin was measured on weight-bearing radiographs
of the entire lower limb. The mean age was twenty-four years for
the male volunteers and twenty-three years for the female volunteers.
The results were compared with those of two similar studies of white
volunteers in the United States.
Results: The medial inclination of the tibial
plateau in the Chinese subjects (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 degrees 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 Moreland et al. and Hsu et al., the
Chinese subjects had significantly larger medial inclination of
the knee joint (knee-joint obliquity) (p < 0.005) and the female
Chinese subjects had significantly more varus alignment of the lower
extremity (p < 0.025).
Clinical Relevance: Five degrees of external
rotation of the femoral component, instead of the commonly reported
3 degrees, may be required to obtain a rectangular flexion gap in
total knee arthroplasty in Chinese patients. The racial difference
in the knee-joint obliquity may contribute to the racial difference
in the ratio of knee osteoarthritis to hip osteoarthritis. Additional
studies are necessary to confirm this relationship.