Incidence, risk factors, characteristics and shoulder joint function status of heterotopic ossification following surgical treatment of clavicle fracture or acromioclavicular joint dislocation.

Abstract

Heterotopic ossification (HO) around the shoulder is common in patients with clavicle fracture or acromioclavicular joint (ACJ) dislocation. Periarticular HO sometimes leads to poor joint function. HO of the elbow and hip requires active prevention. However, studies on the incidence, risk factors, characteristics, and shoulder joint function of HO around the shoulder after surgical treatment of clavicle fracture or ACJ dislocation are still lacking. ACJ dislocation, clavicular hook plate fixation and excessive screw length are independent high-risk factors for postoperative shoulder HO; shoulder HO may impair joint function, with its anatomical location potentially being the key influencing factor. This retrospective study enrolled patients with clavicle fracture or ACJ dislocation who underwent surgical treatment from January 2016 to October 2021. Patient radiographs were collected to observe the characteristics of HO, which was classified by location, diameter, and shape. Shoulder function was evaluated using the Visual Analog Scale (VAS), Constant-Murley score, and Disabilities of the Arm, Shoulder and Hand (DASH) score at the final follow-up. A total of 1181 patients were included, with a mean follow-up of 15 months (range, 3 to 122 months). The overall incidence of shoulder HO was 9.05% (n = 98), with 4.46% in clavicle fracture patients and 23.45% in ACJ dislocation patients; the incidence was 17.95% in hook plate fixation and 1.71% in clavicular anatomical plate fixation. Multivariate logistic regression confirmed that increasing age, male gender, smoking index ≥200, ACJ dislocation, clavicular hook plate fixation, and excessive screw length were independent risk factors for HO. The diameter and shape of HO were not associated with shoulder function scores, while the location of HO might affect Constant-Murley and DASH scores. The mean VAS was 0.26 ± 0.58, mean Constant-Murley score was 98.34 ± 2.80, and mean DASH score was 1.15 ± 1.57. No patient had significant shoulder function impairment or vascular nerve entrapment. The overall incidence of shoulder HO after surgical treatment of clavicle fracture or ACJ dislocation is 9.05%. Independent risk factors include increasing age, male gender, smoking index ≥200, ACJ dislocation, clavicular hook plate fixation, and excessive screw length. Most shoulder HO patients have favorable shoulder function without obvious impairment. Routine prophylaxis or targeted treatment is generally not necessary for unselected patients, although individualized evaluation may be warranted in high-risk subgroups.