Rotational Alignment of the Knee is Different in Osteological Specimens with and without a Large Cam Deformity of the Proximal Femur

Purpose We studied a large osteological collection for differences in knee rotation based upon the presence or absence of a large cam deformity of the proximal femur. Methods We obtained 357 matched tibiae and femora from the Hamann-Todd Osteological Collection and measured: femoral head-neck alpha angle, anteroposterior axis (or Whiteside's line) at the distal femur relative to the posterior condylar axis, and position of the tibial tubercle with respect to the posterior condylar axis of the proximal tibia. We then divided these specimens into two groups based upon alpha angle <45° (Group 1, n = 73) or alpha angle >60° (Group 2, n = 122) and performed an independent samples t-test to evaluate for differences in measured parameters between groups using this subset of specimens. Results The mean alpha angles in Group 1 and 2 were 40.9° ± 3.3° and 67.0° ± 5.6°, respectively. Whiteside's line was externally rotated with respect to the posterior femoral condylar axis by a mean of 1.8° ± 6.8° in Group 1, vs. 3.0° ± 3.7° in Group 2 (p = 0.03). The tibial tubercle was externally rotated by a mean of 19.4° ± 6.8° in Group 1, versus 16.6° ± 5.1° in Group 2 (p = 0.003). Conclusions Specimens with femoral head-neck alpha angle >60° demonstrated greater external rotation of the distal femur and a more internally-rotated tibial tubercle compared to specimens with an alpha angle <45°. Differences in anatomic characteristics of the knee may play a role in the development of patellofemoral pain in patients with a large cam deformity.

Distal Femoral Rotational Axes in Indian Knees

Purpose. To measure the angular relationships of distal femoral rotational axes in 100 normal Indian knees. Methods. 42 men and 8 women aged 26 to 40 (mean, 31) years, with 100 normal non-arthritic knees were recruited. Anatomic landmarks were measured using computed tomography. They included the posterior condylar axis, the transepicondylar axis, the anteroposterior axis (Whiteside's line), the posterior condylar angle (PCA), the Whiteside-epicondylar angle (W-EP), and the Whiteside-posterior condylar angle (W-PC). Results. The mean PCA, W-EP, and W-PC were 5°, 90.8°, and 95.8°, respectively. The mean femorotibial alignment was 179.6°. The differences between the left and right sides were significant only for the W-EP and W-PC. Only the PCA and W-EP were weakly correlated ( r=0.338, p=0.001). Conclusion. There are differences in distal femoral rotational axes among Indian, Caucasian, and Japanese knees. Our data can be used to evaluate changes in those axes in ageing or arthritic patients.