In this key-hole procedure, the tight tissues stabilising the lateral (outer) aspect of the patella are divided in order to enable it to sit more centrally in the V shaped groove at the end of the femur (the trochlea). Historically this procedure was very commonly carried out and sadly this remains the case in many units. It is now known that the indications for this procedure are very specific. It is not a benign procedure and patients may take several months to settle following surgery. Because of the limited indications and possible complications associated with the procedure it is no longer a commonly carried out by specialist knee surgeons.
Surgical procedures aimed at stabilisation of the patella are, by and large, only undertaken after the patient's physiotherapy regime has failed to achieve the desired results and are directed at patella instability symptoms.
The MPFL (medial patello-femoral ligament) is the most important soft tissue stabiliser of the patella. When ruptured, it can be reconstructed using a combination of arthroscopic surgery and minimally invasive open surgery. A single hamstring tendon is used to reconstruct the MPFL.
The procedure involves making a small tunnel in the patella and a second tunnel where the original ligament inserted on to the thigh bone (femur). The new ligament is then passed as a loop through the tunnel in the patella and then through the tunnel in the femur and secured in position. Accurate positioning of the patella is ensured as the surgeon is able to view its movement directly during key-hole surgery.
Most patients are ready for discharge the following day. Immediate full weight bearing is encouraged with crutches for the first week or two. No brace is required and patients can expect to get back to physical activity approximately three months from surgery.
Bony re-alignment surgery
Where a patient has a pre-existing bony abnormality causing instability of the knee cap a bony realignment procedure may be indicated. The most common bony problem involves the insertion point for the patella tendon which rather than sitting in the middle is positioned towards the outer aspect of the upper shin (tibia). The amount of deformity and therefore required correction is calculated from an MRI or CT scan of the knee. This is called a TTTG measurement.
The procedure involves detaching the patella tendon together with a small block of bone to which it is attached and moving it a small distance towards the midline. It is then fixed in the new position with one or occasionally two small screws.
Most patients are able to go home the day following surgery. The knee is immobilised in a brace. Patients are not encouraged to weight bear for two weeks after which the knee is progressively mobilised and weight bearing commenced. By six weeks patients are out of the brace, off crutches and taking full weight through the operated knee.