PSI planning

Advances in partial knee replacements

On my website, I discuss the treatment options for knee osteoarthritis. Surgery is not usually the first option. Most people with knee arthritis will be helped with Paracetamol, anti-inflammatory medications, a strengthening program, and weight loss if required. However, surgery may be considered if you have severe disease that interferes with your enjoyment of everyday activities, and the above measures no longer help. The standard treatment is a total knee replacement. This is an excellent operation that affords good pain relief and restoration of function for most patients.

Another option is a partial knee replacement. As its name suggests, only part of the knee is replaced, usually the inside or medial compartment of the knee. With a complete knee replacement, ligaments are deliberately divided or released. However, with a partial knee replacement, ligaments are left alone, which results in close to normal knee mechanics.

Not everyone is suitable for a partial knee replacement. A “partial” is suitable where the pain is localised to the arthritic part of the knee, when there is moderate rather than severe knee deformity, and in a knee that can fully straighten. However, a partial knee replacement cannot be performed if the pain is generalised, if the arthritis is widespread, for a severe deformity and if the knee is very stiff.

It’s been my experience that partial knee replacements offer the best chance of a knee to return to “normal”. Patients often state that they’ve forgotten that they have an artificial knee. Traditionally, however, a partial knee replacement is a technically more difficult. Fortunately, recent technical advances have improved the reproducibility of the operation and hence the success rate.

If you are potentially suitable for a partial knee replacement, additional stress Xrays and “long leg” Xrays will be ordered. If these Xrays confirm the suitability for a partial, then a special MRI is obtained. From this, a technician will create a computer-based model of your knee, and determine the appropriately sized implants to be used and their optimum position. I then review this model and make changes as required. Unique patient-specific guides are created by employing 3-D printing technology that allows for accurate implant positioning. 

The advent of these patient-specific guides has been a real advance in knee surgery.