High Tibial Osteotomy for Right Lower Limb with MPTA of 79.6° and LDFA of 87.1°
High tibial osteotomy (HTO) with bone graft is indicated for this patient with a right lower limb MPTA of 79.6° and LDFA of 87.1°, as these measurements demonstrate varus malalignment that would benefit from surgical correction. 1
Biomechanical Assessment
The patient's measurements indicate significant varus malalignment:
- MPTA (Medial Proximal Tibial Angle) of 79.6° - This is below the normal range of 85-90°, indicating varus alignment at the proximal tibia
- LDFA (Lateral Distal Femoral Angle) of 87.1° - This is within normal range (approximately 85-90°)
This pattern shows that the varus deformity is primarily originating from the proximal tibia rather than the distal femur, making HTO an appropriate surgical choice.
Surgical Indication
According to AAOS guidelines, realignment osteotomy is an option for active patients with:
- Symptomatic unicompartmental osteoarthritis of the knee with malalignment 1
- Varus deformity originating from the proximal tibia 1
The patient's measurements clearly demonstrate tibial varus malalignment that would benefit from correction through HTO. This procedure would:
- Unload the diseased medial compartment
- Correct angular deformity at the tibiofemoral articulation
- Potentially promote cartilage regeneration in the medial compartment 2
Surgical Technique Considerations
For this patient, an opening wedge HTO would be most appropriate:
- The varus deformity is primarily tibial in origin
- Opening wedge technique allows precise correction of the deformity
- Bone graft is essential to prevent delayed union or nonunion 3
The autogenous iliac crest bone graft is recommended as it:
- Promotes early union
- Allows earlier rehabilitation and weightbearing
- Prevents knee arthrofibrosis and patella infera 3
Expected Outcomes
With proper surgical technique and rehabilitation:
- Union rates approach 100% with appropriate bone grafting 3
- Improved MPTA to normal range (85-90°)
- Reduced pain and improved function as measured by WOMAC scores 2
- Potential for cartilage regeneration in the medial compartment 2
Potential Complications and Prevention
Common complications include:
- Delayed union or nonunion (prevented by proper bone grafting) 3
- Loss of correction (prevented by stable fixation) 3
- Arthrofibrosis (prevented by early rehabilitation) 3
- Changes in tibial slope (prevented by proper surgical planning) 3
Post-Operative Protocol
A progressive rehabilitation program should include:
- Protected weightbearing for approximately 8 weeks
- Early range of motion exercises to prevent arthrofibrosis
- Gradual return to full activities as union progresses
- Radiographic monitoring of correction and union 3
Conclusion
The patient's measurements (MPTA 79.6°, LDFA 87.1°) clearly demonstrate a varus malalignment primarily originating from the proximal tibia. HTO with bone graft is the appropriate surgical intervention to correct this deformity, unload the medial compartment, and potentially improve symptoms and function. The use of autogenous bone graft is recommended to ensure successful union and allow early rehabilitation.