A 35-year-old man with medial compartment knee osteoarthritis and 12° varus deformity (mechanical axis deviation to medial compartment) is a candidate for high tibial osteotomy (HTO). The target correction for the mechanical axis post-HTO is:
- A Neutral mechanical axis (Mikulicz line passing through center of knee)
- B 5–6° of undercorrection, maintaining slight varus to reduce lateral compartment load
- C 3–4° of overcorrection into valgus (Mikulicz line shifted to 62–66% of tibial plateau width) ✓
- D Achieving a mechanical axis of 0° tibiofemoral angle
Correct answer: C. 3–4° of overcorrection into valgus (Mikulicz line shifted to 62–66% of tibial plateau width)
Explanation
For medial compartment unloading HTO, deliberate overcorrection to 3–4° of valgus is recommended, placing the Mikulicz line at approximately 62–66% of the tibial plateau width laterally (the Fujisawa point). This ensures effective unloading of the diseased medial compartment while not overloading the lateral compartment. Simply achieving neutral alignment does not sufficiently reduce medial compartment contact stress. Undercorrection leads to early recurrence of deformity and inferior clinical outcomes.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.