Reassessing Valgus Lower Extremity Alignment: Is Lateral Condyle Hypoplasia a Myth?

Area of Science:

• Orthopedic surgery
• Biomechanics
• Radiology

Background:

• Lower-extremity coronal alignment impacts joint loading, gait, and osteoarthritis progression.
• The roles of hip and knee anatomy in alignment are not fully understood.
• Valgus alignment was often attributed to lateral femoral condyle hypoplasia.

Purpose of the Study:

• To investigate the primary anatomical contributors to valgus lower extremity alignment.
• To compare femoral version and tibial bowing in valgus versus varus knees.
• To challenge traditional beliefs regarding the etiology of valgus deformity.

Main Methods:

• Retrospective review of 122 primary total knee arthroplasties.
• Analysis of preoperative long-leg radiographs and hip-to-ankle CT scans.
• Measurement of hip-knee-ankle angle, tibial shaft angulation, femoral version, and femoral condyle heights.
• Statistical comparison between valgus and varus groups using ANCOVA, t-tests, and Chi-square analyses.

Main Results:

• Valgus alignment showed significantly lower femoral anteversion (5.5°) compared to varus alignment (10.3°).
• Femoral retroversion was more prevalent in valgus knees (30% vs. 3%).
• Medial tibial bowing (>3°) was common in valgus knees (50.9% vs. 3%).
• Lateral femoral condyle height was unexpectedly greater in the valgus group.

Conclusions:

• Valgus lower extremity alignment is strongly associated with femoral retroversion and medial tibial bowing.
• Lateral femoral condyle hypoplasia is not a primary driver of valgus deformity.
• Findings necessitate reassessment of valgus deformity pathogenesis and pre-operative planning for knee and hip arthroplasty.