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.