Position
- patient supine on radiolucent table
- place ECG lead and artery clip over centre of femoral head
- useful to put II ipsilateral to leg, and place knee on cassette
- can get repetitive AP and lateral as needed
- tourniquet, IV ABx
- may need to be able to take iliac crest bone graft
- can get pre-prepared allograft wedges (Arthrex)
- can also may allograft wedges from a femoral head allograft
Equipment
- company specific jigs to guide tibial osteotomy
- puddhu plate system from Arthrex
- medial locking plate for larger corrections > 20o
- synthetic / allograft autograft bone graft wedges
Incision
- medial
- close to midline to incorporate into later TKR
- elevate pes and MCL, close later
Exposure
- must expose entire posterior tibia subperiosteally
- combination Bristow and Cobbs
- should be able to place finger entirely across tibia to proximal tibio-fibular joint
- expose behind patella tendon above tibial tuberosity
- place Langenbeck / Homan retractors anteriorly and posteriorly
Oblique Osteotomy
- entry is 5 cm distal to joint line aiming for just above tip fibula head
- osteotomy must pass above TT
- must leave enough proximal bone laterally to avoid lateral fracture (2cm) and complete fracture / instability
- leave the proximal tib-fib joint intact to stabilise laterally
- stay 1 cm below the tibial plateau to avoid intra-articular fracture
Tip
- place two needles in joint line
- gives guide of posterior tibial slope
- place pins so that it replicates this slope
- check xray
- ensures that you don't inadvertently alter the slope
Arthrex guide
- place superior pin parallel to joint line
- should aim laterally for where the osteotomy is to exit (2cm below joint line)
- apply jig
- place 2 inferior break off pins in line with proposed osteotomy
- ensure parallel to tibial joint line / reconstruct posterior slope
- apply cutting block
- use oscillating saw
- stop 2 cm short of lateral cortex (mark on blade length that is 2 cm short of length of pins)
- check repeatedly on II
Opening of wedge
- use osteotomes to complete osteotomy
- need to ensure get anterior and posterior cortex
- if having difficulty may need to perform fibular osteotomy
Stabilisation
- insert trial wedges of desired thickness (i.e. 10 mm)
- ensure weight bearing axis now passes through lateral joint (diathermy lead)
- insert appropriate angle Puddhu plate
- release trial wedges so the bone rests on the plate and recheck alignment
- secure with locking screws
Bone graft
A. Insert combination of tricortical and cancellous bone graft
- tamp cancellous in lateral wedge
- then insert tricortical iliac crest graft (take same size as opening wedge)
B. Insert predesigned allograft wedges
Post op
Insert a drain subcutaneously in skin, as bleeding v common and closure difficult
- elevate on braun pillow for 48 hours
- monitor compartment syndrome
- PWB 6/52
- monitor for union
Results
Allograft v autograft
Yakobucci et al Am J Sports Med 2008
- 50 patients with average opening wedge 10o
- inserted corticocancellous allograft wedge
- 2/50 (4%) not united at 4 months
Synthetic graft
Koshino et al JBJS Am 2003
- 21 patients with 2 x HA wedges and plate
- good correction and functional outcome in all patients