The lateral retinaculum may become tight if the forces around the kneecap are not in balance - for example, if the vastus medialis muscle (part of the quads) is weak or if the medial retinaculum is stretched.
A tight lateral retinaculum may cause the patella to tilt to one side, and this may trigger pain in the front of the knee. A tight lateral retinaculum may be released surgically by cutting it along its length in a procedure known as 'lateral retinacular release' or 'lateral release'.
Knee surgeons are at pains to point out that lateral release should not be done lightly. If done for the wrong reason, or in an inappropriate patient, or if the procedure is too extensive, then patella instability may be the result and the patient may be made very miserable.
The main indication, knee surgeons now agree, is symptomatic tilt of the patella without subluxation or dislocation.
It is not appropriate in patients who have an anatomic propensity to dislocate, such as patients with patella alta (high riding patella), patellar dysplasia (poorly-shaped patella) or trochlear dysplasia (abnormal groove in which the patella lies).
The cut must not extend into the vastus lateralis muscle, or it will cause inhibition of this muscle and affect the stability of the patella.