Two Cases of Post-Traumatic Osteolysis of the Distal Clavicle

Abstract

Post-traumatic osteolysis of the distal clavicle has been regarded as a rarity, however it occurs more often than generally recognized. This disease has been reported in literature for over 50 years, however, its etiology remains unclear. This report concerns two patients with post-traumatic osteolysis of the distal clavicle and discusses the pathogenesis.
Case reports
Case1 A 22-year-old student injured his right shoulder during snowboarding. Radiographs two months after injury showed osteolysis of the distel clavicle. Angiography showed hypervascularity of the distal clavicle. Case2 A 35-year-old man injured his right shoulder in a motor vehicle accident. Radiographs three months after injury showed osteolysis of the distal clavicle. Surgical excisions of the distal clavicle were performed due to persistent pain. These sections revealed loss of articular cartilage of the distal clavicle, many inflammation cells in the bone marrow of the acromion and the clavicle, overgrowth of the synovium in the acromio-clavicular joint and granulation tissue with a vascular proliferation and multinuclear giant cells covered the distal clavicle.
Discussion
Both cases had no evident fracture or dislocation of the distal clavicle, however, minor recess of the articular surface of the distal clavicle. It may show a minor fracture of the distal clavicle. Histologic examination displayed regions of hypervascular connective tissue and invasive synovial destruction of the bone.
We suggest the possibility that the post-traumatic osteolysis of the distal clavicle arose from osteochondral fracture and synovial invasion.