Is a patient with a 6mm length discrepancy between the right and left lower limbs, abnormal Medial Proximal Tibial Angle (MPTA) of 97 degrees on the right and 98 degrees on the left, and abnormal Lateral Distal Femoral Angle (LDFA) of 93 degrees on the right and 92 degrees on the left, a candidate for high tibial osteotomy and bone grafting?

High Tibial Osteotomy Is NOT Indicated for These Findings

Based on the measurements provided, high tibial osteotomy and bone grafting are not indicated because the patient has essentially normal lower limb alignment without pathological varus deformity. The MPTA angles (97° right, 98° left) and LDFA angles (93° right, 92° left) fall within or very close to normal ranges, and the 6mm leg length discrepancy is clinically insignificant 1.

Why This Patient Does Not Meet Criteria for HTO

Normal Alignment Parameters

• MPTA values of 97-98° are within normal range: The American Academy of Orthopaedic Surgeons defines pathological tibial deformity requiring correction as MPTA <85°, which would indicate significant tibial vara 2, 1.
• LDFA values of 92-93° are normal: These measurements indicate no significant femoral deformity requiring correction 2.
• No pathological varus malalignment exists: HTO is specifically indicated for patients with pathological varus malalignment (typically >5° varus on hip-knee-ankle angle measurement), which this patient does not demonstrate 1.

Leg Length Discrepancy Is Not Clinically Significant

• 6mm difference is below the threshold for intervention: This minimal discrepancy (right 798mm vs left 804mm) does not warrant surgical correction and would not be addressed by HTO in any case 1.
• HTO does not correct leg length discrepancy: The procedure is designed to correct angular deformity and shift weight-bearing load, not to equalize limb lengths 3.

Established Indications for HTO That Are Absent Here

Required Clinical Criteria Not Met

• Symptomatic medial compartment osteoarthritis: HTO is indicated for patients with symptomatic medial compartment OA combined with pathological varus, typically in active patients under 60-65 years 1, 3.
• Pathological varus deformity: The goal of HTO is to correct pathological varus (typically >5° varus) to 3-8° of valgus, shifting load from diseased medial to healthier lateral compartment 1.
• Intact lateral compartment: The procedure requires a relatively preserved lateral compartment to accept the transferred load 1.

Risk of Iatrogenic Deformity

• Creating HTO in normal alignment causes harm: Performing HTO on patients with normal or near-normal alignment creates iatrogenic valgus deformity, leading to lateral compartment overload, pain, and accelerated lateral compartment arthritis 1.
• No therapeutic benefit without pathological deformity: Without pre-existing pathological varus and medial compartment disease, the procedure offers no clinical benefit 1, 3.

When Double-Level Osteotomy Would Be Considered

Specific Deformity Patterns Requiring Combined Correction

• MPTA <85° combined with abnormal LDFA: The American Academy of Orthopaedic Surgeons recommends double-level osteotomy only when both MPTA <85° and LDFA considerations exist to avoid excessive tibial valgus and joint line obliquity 2.
• This patient's measurements do not approach these thresholds: With MPTA 97-98° and LDFA 92-93°, neither tibial nor femoral correction is warranted 2.

Appropriate Clinical Algorithm

What These Measurements Actually Indicate

• Evaluate for symptomatic pathology: If the patient has knee pain, investigate for intra-articular pathology (meniscal tears, cartilage lesions, ligamentous injury) rather than assuming alignment-related disease 1.
• Standing full-length radiographs needed: Obtain standing hip-to-ankle radiographs to measure actual mechanical axis and hip-knee-ankle angle if clinical symptoms warrant further evaluation 1.
• Conservative management first: If osteoarthritis is present, trial physical therapy, weight optimization, and anti-inflammatory measures before considering any surgical intervention 1.

Common Pitfall to Avoid

• Do not perform HTO based on isolated angle measurements without clinical correlation: The measurements provided show normal alignment; performing osteotomy would create pathology rather than correct it 1.
• Recognize that minor variations in MPTA and LDFA are normal: Population studies show variation in these angles, and values in the 90-98° range for MPTA and 88-93° range for LDFA are within normal limits 2, 1.