Approach
1. Incision and skin flaps
- previous incision may be L shaped
- may be good to use a vertical midline incision initially in HTO
- can usually incorporate incision
2. Removal of hardware
- may wish to consider staged procedure
- staples not usually a problem (can ignore)
3. Patella Baja
Problem
- patella eversion and exposure difficulties
- PT at risk for avulsion
- may need to consider quadriceps snip / osteotomy
Bone Cuts
1. Decreased tibial bone stock
Lateral closing wedge
- loss of lateral bone stock
- may rarely need augments
2. Anterior tibial slope
Due to incomplete posterior osteotomy closure
- need to be aware
- ensure correct slope with bone cuts
3. Offset tibial shaft medially
Seen with closing wedge
- need offset stem to avoid lateral overhang
- more common when large corrections have occurred
- have revision stems available
Soft tissue Balancing
Valgus knee alignment
- need appropriate releases
Soft tissue balancing
- restoring the tibial slope
- difficulty with flexion / extension balancing
- may need higher constraint
Results
Controversial
- conflicting reports
Meding Sept 2000 JBJS
39 consecutive AGC bilaterally
- one with HTO / one without
- 8.7 year follow up
- 36 of 39 no side to side difference in pain
- 85% of post HTO no pain