Periarticular Osteotomy for Knee Osteoarthritis

Osteoarthritis is a process of the gradual wearing out of the lining cartilage of the bones forming any joint in the body. In the knee, the lining cartilage covers the end of the femur (thigh bone), the top of the tibia (shin bone) and the undersurface of the patella (knee cap). When the cartilage wears, there is limited ability for it to heal itself and the worn cartilage is often associated with inflammation, pain and swelling of the affected joint.

The knee joint can be thought of as being composed of three compartments - the medial, lateral and patellofemoral compartments. Osteoarthritis may affect one, two or all three of these compartments to various degrees and the treatment for each may be slightly different. When all three compartments have advanced osteoarthritis that is painful, and all non-operative therapy has been exhausted, one appropriate surgical option may be a total knee replacement. However when the osteoarthritis is localised to one compartment and it is not advanced, an osteotomy might be more appropriate.

The aim of a periarticular osteotomy is to offload the compartment of the knee that is symptomatic. The goal is to reduce the painful symptoms of osteoarthritis when weight bearing occurs through the affected compartment. Another added effect is to potentially slow the progression of arthritis in this area. This is achieved by realigning the lower limb in such a way that when walking, weight is taken on the other unaffected part of the joint. For example, if the medial compartment of the knee joint is affected, then the aim is to realign the leg to allow weight to be shifted onto the unaffected lateral compartment.

By changing the alignment of the lower limb, this has the effect of changing the shape and outward appearance of the leg. For example, if an osteotomy is performed when there is initially a “bow-leg” shape to the lower limb, this usually results in a leg that becomes straight or even “knock-kneed”. The same is true for someone who is initially “knock-kneed”, that is, the result is for a straight or bowleg appearance.

The osteotomy may be performed either on the femur or the tibia. If the leg is bowed to begin with, usually the osteotomy is performed on the tibia. If the leg is knock-kneed, then the osteotomy is usually performed on the femur. The former is the more common scenario, and usually the procedure involves realigning the leg by creating a cut in the bone and opening up a wedge shaped gap in the tibia. This is often referred to an opening wedge high tibial osteotomy (OW HTO). Alternatively, the other option for treating the same problem is to remove a small wedge of bone from the cut tibia. This is called a closing wedge high tibial osteotomy (CW HTO). Usually the osteotomy is held stable with a plate and screw type construct or with metallic staples. Both osteotomies have the same overall effect, however there are pros and cons with both. Ultimately, the decision as to which is best is decided on a patient-patient basis after consultation with the surgeon.

The procedure is usually performed under a general anaesthetic, and the inpatient stay can be up to two to three nights. Depending on the surgeon’s preferences, you may have a brace for a period of time postoperatively and you may be non or partial weight bearing with crutches for a period of 6 weeks while the bone heals.