Does a right lower limb with a mechanical proximal femoral angle (MPFA) of 88.5 degrees and a lateral distal femoral angle (LDFA) of 83.5 degrees indicate a need for a distal femur complex bidirectional osteotomy with bone grafting?

Assessment of Distal Femoral Deformity and Surgical Indication

The reported angles (MPTA 88.5° and LDFA 83.5°) indicate significant distal femoral varus deformity requiring surgical correction, and a distal femur osteotomy with autogenous bone grafting is recommended based on current orthopedic guidelines.

Understanding the Deformity

Your measurements reveal:

• Mechanical Proximal Tibial Angle (MPTA): 88.5° - This is within normal range (normal: 85-90°) 1
• Lateral Distal Femoral Angle (LDFA): 83.5° - This is significantly abnormal (normal: 85-90°), indicating distal femoral varus deformity 2, 1

The primary pathology localizes to the distal femur, not the tibia, based on these measurements 1.

Surgical Indication and Approach

Double-level osteotomy considerations:

• The American Academy of Orthopaedic Surgeons recommends that when MPTA <85° AND LDFA abnormalities coexist, double-level osteotomy is indicated to avoid creating excessive tibial valgus and joint line obliquity 2
• In your case, since MPTA is normal (88.5°) but LDFA is abnormal (83.5°), single-level distal femoral osteotomy is appropriate 2, 1

Bidirectional osteotomy:

• The term "complex bidirectional osteotomy" typically refers to correction in multiple planes (coronal and sagittal) 3
• If only coronal plane deformity exists, a standard opening or closing wedge osteotomy may suffice 1
• Assessment of sagittal plane alignment is essential before determining if bidirectional correction is needed 1, 4

Bone Grafting Recommendations

Autogenous bone grafting is strongly recommended:

• The International Journal of Surgery consensus guidelines recommend sufficient autogenous bone graft for osteotomy procedures, particularly opening wedge corrections 2, 5
• Iliac crest bone graft provides optimal structural support for complex corrections 2
• For opening wedge distal femoral osteotomy, bone grafting enhances union rates and prevents collapse 5

Fixation Strategy

Combined fixation approach:

• External fixation combined with internal fixation is recommended for stability in complex deformity corrections 2, 5
• This combination achieves primary union rates of 84% and final union rates of 93.3% 5
• The combined approach is particularly indicated for significant angular deformities requiring precise correction 5

Critical Considerations

Before proceeding:

• Obtain full-length standing radiographs to assess mechanical axis deviation and joint line obliquity 1, 6
• Evaluate for sagittal plane deformities (procurvatum/recurvatum) that may require bidirectional correction 1, 4
• Assess the contralateral limb for comparison and to determine if bilateral pathology exists 6
• Consider CT imaging for precise three-dimensional deformity analysis and surgical planning 4

Common pitfalls to avoid:

• Correcting only the distal femur when joint line obliquity exceeds acceptable limits (>10°) may require tibial correction as well 2
• Inadequate bone grafting in opening wedge osteotomies leads to delayed union or nonunion 5, 2
• Failure to address rotational deformities simultaneously can result in persistent functional impairment 1, 3