Cross-sectional study of 120 healthy adults using full-length weight-bearing radiographs and a rigid-body spring computer model. Establishes normative lower extremity alignment angles and tibial plateau load distribution, stratified by sex and age. Directly challenges the practice of placing TKA tibial components in 3° varus.
The 3° varus tibial component placement once appearing in TKA textbooks lacked a normative foundation — this paper provides it. One hundred twenty healthy adults average only 1.2° varus mechanically, making tibial component placement perpendicular to the tibial mechanical axis the biomechanically justified standard.
When planning TKA or high tibial osteotomy, use the tibiofemoral mechanical angle (hip-knee-ankle) as your primary reference. If you must use the femoral anatomic axis as a surrogate, specify which segment. The distal axis (4.2°) and proximal axis (5.8°) differ by over a degree and a half, enough to meaningfully change your resection angle.
The 75% medial plateau loading explains the clinical observation directly: medial compartment OA predominates even in well-aligned knees. The linear relationship between varus and medial load (R = 0.824) is why even modest correction in high tibial osteotomy produces meaningful unloading.
In female patients presenting with anterior knee pain, higher Q angles and higher plateau pressures are normal variants at baseline. They lower the threshold for patellar pain syndrome but do not by themselves represent pathology.
Cross-sectional study of 120 healthy adults using full-length weight-bearing radiographs and a rigid-body spring computer model. Establishes normative lower extremity alignment angles and tibial plateau load distribution, stratified by sex and age. Directly challenges the practice of placing TKA tibial components in 3° varus.
The 3° varus tibial component placement once appearing in TKA textbooks lacked a normative foundation — this paper provides it. One hundred twenty healthy adults average only 1.2° varus mechanically, making tibial component placement perpendicular to the tibial mechanical axis the biomechanically justified standard.
When planning TKA or high tibial osteotomy, use the tibiofemoral mechanical angle (hip-knee-ankle) as your primary reference. If you must use the femoral anatomic axis as a surrogate, specify which segment. The distal axis (4.2°) and proximal axis (5.8°) differ by over a degree and a half, enough to meaningfully change your resection angle.
The 75% medial plateau loading explains the clinical observation directly: medial compartment OA predominates even in well-aligned knees. The linear relationship between varus and medial load (R = 0.824) is why even modest correction in high tibial osteotomy produces meaningful unloading.
In female patients presenting with anterior knee pain, higher Q angles and higher plateau pressures are normal variants at baseline. They lower the threshold for patellar pain syndrome but do not by themselves represent pathology.