High Tibial Osteotomy – Technique
– Start with the patient selection – is this patient a good candidate?
– make sure you note range of motion and stability of the knee – in particular, do they have excessive MCL laxity (greater than just pseudolaxity) so that when you correct them they may just keep going into valgus?
Preoperatively template the cut – where in relation to the joint line, and how much of a wedge?
Equipment: radiolucent table, tourniquet, image intensifier, cutting jig, fixation device
Antibiotics prior to the inflation of tourniquet
Choice of incisions: transverse at level of fibular head, curvilinear, or straight midline. Might as well go straight midline because it will make your subsequent TKA easier.
– Lift off anterior compartment in sub-periosteal fashion to expose the proximal tibia.
– The first cut is made approximately 2.0 cm distal to the joint line: use pins and a cutting guide
– Mark off your oblique cut according to pre-operative templating: use pins and a cutting guide. Be aware that with this cut you adjust not only the coronal alignment but also the sagittal – don’t forget the normal posterior slope of the tibia!
– Leave the medial cortex intact for stability, but make sure you get fully across on both cuts, particularly the superior cut (if you don’t, you risk fracturing up into the joint!)
– Expose the fibula 160 cm from the tip and make an oblique osteotomy (the two danger zones are from 0-40 mm – motor branch to tibialis anterior, and from 68-153 mm – motor branch to EHL)
– Fix with multiple stepped staples or Weber semitubular tension band plate
– Prophylactically perform anterior fasciotomy.
– doing the osteotomy proximal to the tibial tubercle unfortunately leaves the patellar tendon lax initially – it eventually contracts/scars and leaves you with patella infera which can make your subsequent TKA exposure difficult
– don’t go any closer than 2 cm to the joint with your superior cut – risk intra-articular fracture when closing the osteotomy if you go close
– the closer to the joint line, the more “truncation” or overlap you get, but the better the healing. Going farther from the joint line minimizes the truncation, but the nonunion rate is much higher.
– there are a number of different described techniques of fixation
– there are a number of different ways to address the fibula – you can also dissect out the nerve, then cut the bone proximally. Disarticulating the tib-fib joint or resecting the fibular head will allow correction of the varus, but may lead to LCL instability.
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