Are LDFA and MPTA measurements of 87/89 and 83/84 respectively justified for high tibial osteotomy (HTO) and bone graft?

Assessment of LDFA and MPTA Values for High Tibial Osteotomy Indication

Your measurements (LDFA 87°/89° and MPTA 83°/84°) indicate bilateral tibial vara deformity that does NOT justify high tibial osteotomy, as HTO is indicated only for patients with symptomatic medial compartment osteoarthritis and pathological varus malalignment, not for isolated anatomical angle abnormalities. 1

Understanding Your Measurements

Your angles reveal the following deformity pattern:

• LDFA (Lateral Distal Femoral Angle): Right 87°, Left 89° - both are normal (normal range 85-90°) 1, 2
• MPTA (Medial Proximal Tibial Angle): Right 83°, Left 84° - both show significant tibial vara deformity (normal range 85-90°) 2, 3

This represents isolated bilateral tibial deformity with approximately 4-5° of tibial vara on each side, while your femoral angles remain within normal limits 2.

Why HTO Is NOT Indicated Based on Angles Alone

HTO requires specific clinical indications beyond anatomical measurements:

• The American Academy of Orthopaedic Surgeons specifies that HTO is indicated for patients with symptomatic medial compartment osteoarthritis, pathological varus malalignment, active lifestyle, typically under 60-65 years, and intact lateral compartment 1
• Pathological varus malalignment requiring HTO is defined as a hip-knee-ankle angle showing more than 5° of varus deformity, not isolated MPTA measurements 1
• HTO is not indicated for patients with normal or near-normal alignment angles, as it can create iatrogenic valgus deformity leading to lateral compartment overload 1

Critical Missing Information

You must obtain standing full-length hip-to-ankle radiographs to measure:

• Hip-knee-ankle (HKA) mechanical axis angle - this determines if you have actual pathological varus requiring correction 1
• Presence and location of osteoarthritis - HTO is a joint-preserving procedure for symptomatic OA, not an isolated deformity correction 1
• Assessment of ligamentous stability and meniscal integrity 1

When Your Deformity Pattern Would Require Intervention

If you have symptomatic varus malalignment requiring correction:

• With MPTA of 83-84°, isolated HTO would require overcorrection to MPTA ≥95° to prevent recurrent varus deformity, which creates an oblique joint line and is biomechanically unfavorable 2, 3
• Research demonstrates that only 12% of varus knees can be appropriately corrected with isolated HTO if anatomic correction (MPTA ≤90°) is maintained 2
• If overcorrection to MPTA ≤95° is accepted, 57% of patients can undergo isolated HTO, but this still leaves your angles requiring excessive correction 2
• Double-level osteotomy (both proximal tibia and distal tibia) may be more appropriate for bow leg deformity with tibial vara throughout the bone length 4

Regarding Bone Graft

Bone graft use depends on the osteotomy technique, not the pre-operative angles:

• Medial opening wedge HTO can be performed without bone grafts using locking-compression plates 3
• The decision for bone grafting relates to gap size created during correction and surgeon preference 3

What You Should Do Next

Follow this diagnostic pathway:

1. Obtain standing full-length hip-to-ankle radiographs to measure actual mechanical axis (HKA angle) 1
2. Document presence or absence of knee pain, location of pain, and functional limitations 1
3. If symptomatic medial compartment OA is present, trial conservative management for 3-6 months including physical therapy, weight optimization, and anti-inflammatory measures 1
4. If you have asymptomatic isolated tibial vara without OA, no surgical intervention is indicated 1

Common Pitfalls to Avoid

• Never proceed with HTO based solely on MPTA measurements - the hip-knee-ankle mechanical axis determines surgical indication, not isolated angle measurements 1, 2
• Do not assume tibial vara requires correction unless accompanied by symptomatic osteoarthritis and pathological mechanical axis deviation 1
• Recognize that overcorrecting MPTA beyond 95° creates excessive valgus, leading to lateral compartment overload and accelerated lateral arthritis 1, 3
• Avoid single-level HTO when tibial deformity exists throughout the bone length (bow leg pattern), as double-level tibial osteotomy provides better correction 4