A lateral retinacular release is a procedure able to be performed with arthroscopic (keyhole) technique where a thickened and tight band of tissue along the outside or lateral aspect of the patella (knee cap) is released.  This procedure is used to help the patella track more normally, alleviate the symptoms of chondromalacia patella and delay the rate of progression of patellofemoral arthritis.

The anterior compartment of the knee is largely made up of the patellofemoral joint where the knee cap (patella) glides up and down a groove shaped part of the front of the femur (trochlea).  Above the knee cap is the quadriceps tendon and a large pouch shaped cavity (suprapatella pouch) and below it is the patella tendon and a fatty pad of tissue (Hoffa’s fat pad) in front of the lower portion of the tendon before it attaches onto the tibia.

On the inside or medial aspect is a deep recess (medial gutter) with the capsule and ligaments running from the medial aspect of the femur to the patella forming the medial retinaculum, and on the outer or lateral aspect is a matching lateral gutter, with the capsule and lateral patellofemoral ligaments forming the lateral retinaculum. The patellofemoral joint should normally run in a smooth and co-ordinated manner with the patella gliding up and down centrally along the trochlea groove with equal amounts of pressure along both the medial and lateral side of the joint.

In a number of pathological conditions, the patella can deviate from this normal pattern including one where the patella tilts and slides excessively laterally, so that an undue amount of force passes through the lateral side of the patellofemoral joint. This is known as a lateral patella pressure syndrome. It can result in associated conditions including deterioration of the articular cartilage from its normally thick, resilient and uniformly smooth surface to one where the cartilage begins to thin, split and become irregular and roughened in patches, known as chondromalacia patella. This is initially, a painless phenomenon, and often first manifesting as an audible grinding noise when squatting or kneeling down or bending the knee back and forth.

The condition usually progresses over time and as the cartilage wears further progresses towards loss of cartilage and arthritis, with pain and swelling becoming an increasing aspect of the condition. It can also be seen in patients who have a history of patellofemoral instability, where the patella moves laterally out of the trochlea groove and into the lateral gutter, either partially during a patella subluxation, or completely during a patella dislocation.

In some early cases physiotherapy, with different modalities including stretching of the lateral retinaculum, can decrease the symptoms and delay progression of this condition. If these symptoms fail to stabilise or progress in spite of such therapy, consideration of a surgical release of this tough fibrous lateral band of tissue (lateral retinacular release) may be necessary. Historically this required an open incision along the lateral aspect of the front of the knee, but it can reliably be done now with keyhole surgery, and if there are any unstable flaps of cartilage arising from the patella or trochlea they can be tidied up (chondroplasty) at the same time using arthroscopic tools.

It usually requires an overnight stay in hospital and a longer period to recover than a simple arthroscopy, with a splint for three or four days, crutches for one to two weeks and up to one or two months for the swelling from the lateral release to resolve. If patients have not got a tight lateral retinaculum, or associated lateral patella tilt or subluxation with an asymmetric lateral pattern of chondral wear, then it is unlikely that a lateral release will be of benefit, and in some cases may be detrimental, and it is important that careful consideration of the patients anatomy and pathology be made before considering whether to perform a lateral release or not.

Whilst most patients if carefully selected for this procedure will experience some benefit, it may also be considered as part of a comprehensive approach to delay the rate of progression of the patients patellofemoral arthritis, holding the patients symptoms at that level with minimal or no significant improvement in the initial post-operative period, but combined with weight loss, activity modification, sensible use of simple analgesia and anti-inflammatory agents and possible viscosupplementation procedures, that the patients symptoms may be minimised for the longest period possible whilst avoiding larger operations such as realignment surgery or replacement (arthroplasty).