A patient with severe tricompartmental osteoarthritis of the knee is planned for total knee replacement (TKR). The PRIMARY biomechanical goal of TKR is:

• A Restoration of the tibial slope to exactly 7 degrees posterior
• B Restoration of the mechanical axis through the centre of the knee ✓
• C Femoral component rotation parallel to the epicondylar axis
• D Replication of Q-angle to prevent patellofemoral complications

Explanation

The PRIMARY biomechanical goal of total knee replacement is restoration of the mechanical axis (the load-bearing axis from the centre of the femoral head through the centre of the knee to the centre of the ankle — the Mikulicz line) to pass through the centre of the knee. Deviation >3° from neutral (varus or valgus) significantly increases polyethylene wear and implant loosening. Other technical parameters (tibial slope, component rotation, Q-angle) are important but secondary to correct mechanical axis alignment, which is assessed on full-length standing AP radiographs.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.