Bone morphotypes of the varus and valgus knee

Area of Science:

• Orthopedic surgery
• Biomechanical analysis
• Osteoarthritis research

Background:

• Total knee arthroplasty (TKA) is vital for correcting coronal deformities in osteoarthritis (OA).
• This study investigated if bone morphology differs in varus and valgus deformities, both pre- and post-osteoarthritis development.

Purpose of the Study:

• To compare bone morphology in knees with varus and valgus deformities before and during osteoarthritis.
• To determine if pre-existing bone shape influences deformity progression and TKA outcomes.

Main Methods:

• Retrospective analysis of 96 TKA patients' full leg standing radiographs.
• Comparison with 46 controls with neutral alignment.
• Measurements included mechanical and anatomical alignment, femoral angles, and intra-articular bone morphology.

Main Results:

• Varus OA knees showed less distal femoral valgus and more tibial varus compared to controls and valgus OA knees.
• Valgus OA knees exhibited distal femoral obliquity and medial opening.
• A constitutional mechanical valgus (184° Hip-Knee-Ankle angle) was noted in the non-arthritic valgus group.

Conclusions:

• Varus deformity in OA involves distal femoral wear, tibial varus, and lateral joint line opening.
• Valgus deformity in OA results from distal femoral obliquity, wear, and medial opening due to ligament stretching.
• Bone morphotype analysis is key for predicting alignment correction potential during TKA.