Panner disease also involves the capitellum and presents in a similar manner as a capitellar osteochondritis dissecans, but in a younger patient population and with a better long-term prognosis. Panner disease typically occurs in the dominant elbow of boys during the period of active ossification of the capitellar epiphysis at between 7 and 12 years of age, with a peak at age 9 years.
The pathologic process is similar to that of Legg-Calvé-Perthes disease and is believed to be caused by interference in the blood supply to the growing epiphysis, which results in resorption and eventual repair and replacement of the ossification center. The exact cause of this avascular necrosis, or bone infarct, continues to be debated, with popular theories including chronic repetitive trauma, congenital and hereditary factors, embolism (particularly fat), and endocrine disturbances. Whatever factors are responsible, the end result is avascular necrosis. Signs and symptoms are similar to those seen with osteochondritis dissecans, including dull, aching lateral elbow pain that is aggravated by use and may improve with rest. Tenderness and swelling along the lateral side of the elbow with loss of terminal elbow extension are also common. Initial radiographic changes can appear similar to osteochondritis dissecans, with fragmentation of the capitellar epiphysis, but whereas lesions of osteochondritis dissecans can often progress to loose fragments, loose bodies are rare in Panner disease. Typically, the normal radiographic appearance of the capitellum will be reconstituted over time as growth progresses. Residual deformity of the capitellum is rare. MRI will demonstrate signal changes in the capitellar epiphysis but may be less useful than in osteochondritis dissecans owing to the lack of concern for an unstable lesion or a loose body.
Symptomatic treatment of Panner disease is sufficient, because the condition is self-limited, with the epiphysis becoming revascularized and returning to a normal configuration with time. Rest and activity modification usually relieve the pain and allow gradual return of elbow motion. Use of a long-arm cast or splint for 3 to 4 weeks may be necessary until pain, swelling, and local tenderness subside. The longterm prognosis is excellent, with complete resolution of symptoms in most patients, althou h a slight loss of elbow extension may persist in some.