High Tibial Osteotomy – how does it work?
A high tibial osteotomy is a procedure performed where the arthritis is mainly on one side of the knee joint either the side of the knee (medial compartment) or the outside of the knee (lateral compartment). Most commonly patients have medial compartment osteoarthritis and the high tibia osteotomy is performed in order to take the load off the medial compartment and shift it to the lateral compartment. It is a very effective procedure in alleviating symptoms and making patient’s pain free particularly in younger patients who are not suitable for joint replacement surgery. There are number of prerequisites before someone is suitable for a high tibial osteotomy and firstly the patient must show a mal alignment in their weight bearing axis, this means that they are abnormally loading one side of the knee joint compared to the other. The way we diagnosis this is by getting special x-rays which involve taking long leg views of the hips, knees and ankles together and working out how much a patient is loading on one side of the knee compared to the other. The most common deformity we see is when patients have abnormally bowed legs so someone is then loading the inside of the knee too much and these patients can potentially have a high tibial osteotomy to straighten the leg and shift the load from the inside (medial compartment) to the outside (lateral compartment). In order for the procedure to be successful the outside of the knee must be completely normal otherwise the patient will have on going pain once the load has been shifted. A high tibial osteotomy is commonly performed for medial compartment osteoarthritis where the leg is bowed and the load is shifted from the inside to the outside of the knee. More rarely patients have lateral compartment osteoarthritis and an osteotomy is performed to shift the load from the outside to the inside of the knee. This osteotomy’s is performed in the distal femur or the thigh to shift the load.
When we are assessing if someone is suitable for an osteotomy we perform a detailed history and examination generally people will be younger and fairly active although there is no age limit on the osteotomy. We will always perform long leg alignment views to check the patient’s axis and an MRI scan to look at the rest of the knee joint. The actual procedure involves an operation where the patient is placed under aesthetic and a controlled break is made in the bone and in the high tibial osteotomy the tibia or shin bone is opened up to shift the load from the inside to the outside of the knee. Some plates and screws are inserted as well as bone graft. Patients are on crutches for around 6 weeks or so. The wounds take about a week to two weeks to heal up. The actual controlled break takes around 6-12 weeks to heal fully. Patients can usually fully weight bear after six weeks and the full recovery is more like 6 months. There are some risks and complications, the main risks include infection, clots, failure of the osteotomy to heal properly and failure to completely relive all symptoms. The overall osteotomy results are approx. 80% of patients have good results at 10 years.