Immunohistochemical analysis for neural markers of the lateral retinaculum in patients with isolated symptomatic patellofemoral malalignment. A neuroanatomic basis for anterior knee pain in the active young patient.

We evaluated 13 lateral retinacula excised at the time of Insall proximal realignments or isolated lateral retinacular releases performed in patients with isolated symptomatic patellofemoral malalignment recalcitrant to nonoperative treatment. Evaluation was performed by means of conventional histologic and immunohistochemical analysis for neural markers (S-100 protein, neurofilament protein, substance P, and neural growth factor). The observations reported here provide a neuroanatomic basis for anterior knee pain syndrome in active young patients with isolated symptomatic patellofemoral malalignment and support the clinical observation that the lateral retinaculum may have a key role in the origin of this pain as a result of increased neural growth factor production, which induces proliferation of nociceptive axons, mainly in a perivascular location.