Evaluation of three-dimensional scapular kinematics and shoulder function in patients with short malunion of clavicle fractures.

BACKGROUND: The presence of short malunion of clavicle fractures could result in alterations in static scapular position and dynamic scapular motion. Nevertheless, no report has ever addressed the kinematic changes of the scapula in patients with short malunion of clavicular fractures. The goal of this study was to compare the changes of shoulder function, and the consequent scapular kinematic changes between the fractured side and the sound side of the shoulder in non-surgically treated patients.

METHODS: Fourteen patients with a short malunion (>10 mm) of midshaft clavicular fracture following conservative treatment were recruited. Outcome analysis included standard clinical follow-up, plain radiography, Shoulder Pain and Disability Index (SPADI) score, shoulder range of motion (ROM), shoulder muscle strength and scapular resting position. The 3-dimensional scapular motion during arm movement in the scapular plane was recorded using an electromagnetic tracking device. The kinematic changes between the fractured side and sound side were analyzed.

RESULTS: The mean shortening length of the clavicle was 12.9 ± 2.8 mm. The fractured sides showed a significantly higher SPADI score and limited ROM in both shoulder flexion and abduction. Significantly weaker shoulder external rotators (1.1 kg, p = 0.017) and lower trapezius (0.7 kg, p = 0.041) were found in the fractured sides when compared with the sound side. The fractured side exhibited significantly more forward shoulder (3.9 mm, p = 0.034) and slightly more anteriorly tilted scapula (5.8°, p = 0.094) in static scapular position. Scapular kinematics showed that the fractured side trended toward greater scapular internal rotation and smaller posterior tilt during arm elevation and lowering phases, especially after the arm rising above horizontal level.

CONCLUSIONS: This study showed that significant changes in scapular kinematics and shoulder function were found after short malunion of clavicle fractures. Recognition and evaluation of the changes could lead to a comprehensive framework regarding the treatment of shortened clavicle fractures.