Undercorrection /  loss of correction 


Most important factor in good results and duration of results

- must correct to 8o of valgus

- mechanical axis must pass through lateral joint line


HTO Insufficient Correction



- inadequate initial correction

- loss of correction (failure fixation, failure bone grafts, non union)


CPN Palsy 


Common 2-3%

- pressure from cast or 

- direct injury during operation (closing wedge)

- anterior compartment syndrome (opening wedge)




A.  Intra-articular


HTO Closing Wedge Intra-articular fracture


Occur in opening or closing wedge



- proximal fragment too small

- osteotomy too incomplete / trying to preserve far cortex for stability



- proximal fragment minimum 15 mm thick

- osteotomy within 10 mm of far cortex

- drill holes in far cortex

- slow correction to allow stress relaxation


B.  Unstable Osteotomy / Fracture Far Cortex


HTO Closing Wedge Medial FractureHTO Closing Wedge Medial Fracture Callous



- don't penetrate medial lateral side

- slow correction

- after plastic deformity / not fracture



- place a Richards staple / plate over fracture site


Compartment syndrome


Unknown incidence


Avoid by

- reduced by using drain

- don't close compartment

- avoid regional blocks

- monitor closely




Can complicate future TKR

- difficult to manage

- essentially have infected fracture

- principles of control infection / maintain stability / obtain healing




Up to 40% rate of DVT

- reports of fatal PE

- need to use prophylaxis


Non union


Problematic in opening wedge

- smoker

- diabetic

- large corrections


<1% incidence in closing wedge above tibial tuberosity


Patella baja


Closing wedge

- caused by immobilisation and contracture

- eradicated by rigid internal fixation and aggressive early ROM



- anterior knee pain

- subsequent TKR difficult


Also seen in anterior wedge