Is a left-sided medial proximal tibial angle (MPTA) of 83 degrees and a lateral distal femoral angle (LDFA) of 90.5 degrees an indication for high tibial osteotomy (HTO) and bone graft?

High Tibial Osteotomy Indication for MPTA 83° and LDFA 90.5°

A high tibial osteotomy (HTO) is indicated for a left-sided medial proximal tibial angle (MPTA) of 83° and lateral distal femoral angle (LDFA) of 90.5° to correct the varus alignment and prevent progression of medial compartment osteoarthritis.

Radiographic Analysis and Indications

• The MPTA of 83° indicates a varus tibial deformity, as normal MPTA values range from 85-90° 1
• The LDFA of 90.5° is within normal limits (approximately 87-90°), suggesting the deformity is primarily tibial rather than femoral 2
• This combination of angles indicates a varus knee alignment that could benefit from correction through HTO 1, 2

Surgical Decision Making

• HTO is appropriate when there is a varus deformity primarily originating from the proximal tibia (as indicated by MPTA <85°) 1
• The goal of HTO is to achieve a postoperative MPTA between 88-95° to correct the mechanical axis and redistribute weight-bearing forces 2
• Research indicates that a postoperative MPTA of at least 95° is optimal to prevent recurrent varus deformity after medial opening wedge HTO 1

Type of Osteotomy Recommended

• For this patient with MPTA 83° and LDFA 90.5°, a medial opening wedge HTO would be appropriate as the primary deformity is tibial 1, 2
• A double-level osteotomy (DLO) would not be necessary since:
  • The LDFA is within normal range (90.5°) 2
  • DLO is typically reserved for cases where HTO alone would result in excessive MPTA (>95°) or when there is a combined femoral and tibial deformity 2

Bone Grafting Considerations

• Bone grafting is recommended with medial opening wedge HTO to:
  • Provide structural support to the osteotomy site 3
  • Enhance healing and reduce the risk of delayed union or nonunion 3
  • Fill the gap created by the opening wedge, especially for larger corrections 3

Expected Outcomes and Complications

• HTO with bone grafting can effectively correct the varus alignment and improve joint biomechanics 1, 2
• Potential complications include:
  • Infection at the osteotomy site (reported in up to 18.8% of cases) 3
  • Loss of correction if inadequate fixation or bone grafting 3
  • Lateral tibial plateau fracture during the procedure 3
  • Joint line obliquity changes (JLO may increase from approximately 1.4° to 6.3° after OWHTO) 4

Postoperative Considerations

• Regular clinical and radiographic follow-up is essential to monitor correction maintenance 5
• Physiotherapy should be emphasized for maintaining joint range of motion, strength, and endurance 5
• Weight-bearing exercises should be incorporated into rehabilitation once appropriate healing has occurred 5

Conclusion

The radiographic parameters (MPTA 83° and LDFA 90.5°) indicate a varus knee deformity primarily of tibial origin, which is an appropriate indication for high tibial osteotomy with bone grafting. This procedure can effectively correct the mechanical alignment and potentially delay the progression of medial compartment osteoarthritis.