A 62-year-old man with symptomatic varus gonarthrosis (medial compartment OA) and moderate deformity presents requesting joint-preserving surgery. He has an active lifestyle and is BMI 27. High tibial osteotomy (HTO) is planned. The ideal correction target for valgus-producing HTO is to achieve:

• A 4–6° of overcorrection into valgus (mechanical axis passing through lateral tibial plateau at 62–66% point) ✓
• B Neutral alignment (mechanical axis passing through knee center)
• C 10° of overcorrection to maximally offload the medial compartment
• D 5° of residual varus to preserve lateral compartment protection

Explanation

The goal of medial opening-wedge HTO for medial compartment OA is to shift the mechanical axis laterally — overcorrecting to approximately 3–5° of anatomic valgus (mechanical axis at approximately 62–66% across the tibial plateau from medial side). This transfers load from the diseased medial compartment to the healthy lateral compartment. Under-correction (neutral) fails to adequately offload the medial compartment. Over-correction to 10° causes lateral overload and accelerated lateral compartment degeneration. This targeting principle is the key to optimizing outcomes in joint-preserving surgery.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.