Musculoskeletal ImagingE3010. Distal Clavicular Osteolysis: An Under-Recognized Cause of Shoulder Pain
Halonen N1, Thoma D1, Ali-Khan M.1,2 1. Tripler Army Medical Center, Honolulu, US; 2. Uniformed Services University of the Health Sciences, Bethesda, US
Address correspondence to N. Halonen (email@example.com)
Background Information: Distal clavicular osteolysis (DCO) must be considered as a cause of shoulder pain in patients who present with pain that localizes to the acromioclavicular (AC) joint. Patients may have a history of remote trauma to the AC joint, resulting in the radiographic findings of bone resorption at the distal clavicle. However, atraumatic DCO is an often under recognized finding that is increasing in incidence due to the popularity of weightlifting and extreme exercise. A recent retrospective review of atraumatic DCO in young patients cites an incidence of 6.5%, with overhead sports and weight training listed as risk factors. A subsequent study found that increasing bench pressing weight, frequency, and duration also increases the risk of DCO. In the military, weight training is not just a popular activity among athletes and elite units, but essentially an occupational requirement with semiannual physical fitness tests mandated by all military services. By virtue of its young, active population and mandatory fitness requirements, active duty military personnel are at increased risk of DCO.
Educational Goals/Teaching Points: The goal of this educational exhibit is to increase awareness of DCO as a cause for shoulder pain, especially among military members and weightlifters without history of traumatic injury. Radiographic findings include focal osteopenia and an irregular or discontinuous cortical margin of the distal clavicle. Erosion of the acromial cortex suggests other etiologies such as infection or arthritis. On MRI, DCO manifests as bone marrow edema in the distal clavicle. Osseous fragmentation, subchondral cystic change, and fluid in the AC joint may also be seen. Focal radiotracer uptake at the distal clavicle can be seen on bone scan. It should be noted that imaging findings of traumatic and atraumatic DCO are essentially identical, and that an accurate clinical history is necessary to distinguish between the two.
Key Anatomic/Physiologic Issues and Imaging Findings/Techniques: Conservative treatment is the mainstay of therapy, with cessation or alteration of activity, ice, and nonsteroidal anti-inflammatory drugs. Surgical resection of the distal clavicle is effective in relieving symptoms of patients that do not respond to conservative management. A potential pitfall to avoid is misdiagnosing DCO as osteoarthritis (OA) of the AC joint. Radiographic signs of OA (minimal osteophyte formation) can manifest as early as the fourth decade. With treatment, most patients can expect near-complete resolution of symptoms, making a timely accurate diagnosis imperative.
Conclusion: Radiologists have the opportunity to provide real value to patients and referring physicians by being familiar with the radiographic findings of DCO, a disease process that can be attributed to chronic overuse injury and tends to respond well to conservative management. Misdiagnosis or failure to diagnose DCO can lead to delays in treatment, with potential deleterious effects on a patient’s athletic or military career.