Patella instability is a broad term that covers a wide range of conditions including patellar subluxation and dislocation.
The patella slots into a groove at the end of the thigh bone, called the trochlear groove. It slides up and down along this groove as you bend and straighten your knee. For individuals with kneecap instability, the patella sometimes becomes displaced from this groove. If the displacement is partial, the condition is known as patellar subluxation. If it is total, you have suffered a patellar dislocation. In either event, your condition can be classified as patella instability.
Symptoms of patella instability may include difficulty walking on the affected knee and a buckling or locking sensation in the knee. In addition, you may experience pain underneath the kneecap, especially when performing activities that require deep knee bends. For individuals whose kneecap has become completely displaced, surgery may be necessary to restore it to its rightful place.
If your patella subluxation or dislocation is an initial case and there is no indication that it is a chronic issue, doctors may try to treat the problem conservatively. Conservative treatments will usually involve rest, use of pain relief medication and wearing a special type of knee brace known as a patella stabilizer.
However, if you have suffered repeated dislocations or subluxations, this may be an indication of chronic patella instability. This can be due to damaged knee cartilage or ligaments, in which case your doctor may need to operate to remove the underlying causes.