Extensive Posterior–Inferior Heterotopic Ossification in Chronic Grade V Acromioclavicular Injury Blocking Reduction During Surgical Repair: A Report of Two Cases

Excerpt

Acromioclavicular (AC) joint dislocations are among the most common shoulder injuries [7, 14]. Heterotopic ossification (HO) of the structures adjacent to the AC is recognized to occur after injury; however, the incidence and location of the HO is poorly defined [4]. In general, formation of heterotopic bone is associated with immobilization after trauma, severe burn wounds [12], spinal cord injury [5], and head injury [6, 11]. In the setting of AC, joint dislocation ossification is conventionally thought to directly involve damaged coracoclavicular and coracoacromial ligaments [4, 10]. The HO may also be seen after distal clavicle excision [2, 16]. In the two cases reported, heterotopic bone formation was found posterior–inferior to the lateral clavicle and actually blocking reduction of the clavicle during surgical reconstruction. In both cases, excision of the heterotopic bone through significant additional dissection and exposure was required for anatomic reduction of the clavicle and AC joint. These cases highlight the importance of analysis of preoperative imaging when HO is present in chronic high-grade AC injuries. Careful scrutiny of preoperative imaging will best prepare the surgeon for optimizing the opperative approach and help counsel patients to risks of surgery. …