Proximal Tibiofibular Joint Instability: An Underrecognized Cause of Lateral Knee Pain and Mechanical Symptoms.

Instability of the proximal tibiofibular joint is an uncommon and often unrecognized cause of lateral knee pain, mechanical symptoms, and instability. The condition results from one of three etiologies: acute traumatic dislocation, chronic or recurrent dislocations, and atraumatic subluxations. Generalized ligamentous laxity is a key predisposing factor for atraumatic subluxation. Instability of this joint may be in the anterolateral, posteromedial, or superior directions. Anterolateral instability is the most common type (80% to 85%) frequently occurring with hyperflexion of the knee with the ankle plantarflexed and inverted. Patients with chronic instability report lateral knee pain with snapping or catching often leading to a misdiagnosis of lateral meniscal pathology. Subluxations may be treated conservatively with activity modification, supportive straps, and knee-strengthening physical therapy. Chronic pain or instability is an indication for surgical treatment including arthrodesis, fibular head resection, or soft-tissue ligamentous reconstruction. Newly developed implants and soft-tissue graft reconstruction techniques provide secure fixation and stability with less invasive procedures and without the need for arthrodesis.