Lateral retinaculum

It is not a discrete anatomical structure but has complex anatomy which is difficult to delineate because of converging and interdigitating structures. There is no common agreement as to their nomenclature or exactly which of the structures comprise the lateral retinaculum -

• A superficial fascia layer acts like a brace and is not attached directly to the patella, but rather to the structures to the side of it.
• The middle layer is a tensioning layer - both the vastus lateralis (via its aponeurosis) and the iliotibial band (ITB) affect the function of the lateral retinaculum. A tight iliotibial band is likely to play a role in aggravating lateral patellar tracking. A broad fibrous band extends from the ITB to the lateral side of the patella and it is very strong. This layer only indirectly attaches to bone of femur and tibia via the attachments there of the ITB.
• The deepest capsular layer is the only one attaching the patella directly to the femur, and it includes -
• the lateral patellofemoral ligament
• the lateral patellomeniscal ligament

The lateral retinaculum is surgically released (cut) during the procedure known as 'lateral release' or 'lateral retinacular release', but it is becoming recognised amongst knee surgeons that this procedure has been inappropriately used in the past, and lateral release for lateral patellar instability (when the kneecap dislocates to the outside of the knee) has often contributed to the patient suffering instead from medial patellar instability (when the kneecap dislocates to the inside of the knee).

Fewer and fewer knee surgeons are using the procedure of lateral release and for fewer indications.

Refs

1. Merican AM, Sanghavi S, Iranpour F and Amis AA. The structural properties of the lateral retinaculum and capsular complex of the knee. J Biomech. 2009,42(14): 2323–2329. [Click here for open access]

2. Anatomy of the lateral retinaculum of the knee. [Merican AM and Amis AA. Anatomy of the lateral retinaculum of the knee. J Bone Joint Surg [Br] 2008;90-B:527-34.]