We report the case of a 31-year-old male orthopaedic resident, who presented to our emergency department after a snowboarding accident. On the same morning the patient fell off a rail obstacle in a snowboard park onto his left shoulder. After the direct blast to the shoulder, the patient felt a sudden separation of the AC joint.
Upon admission, the patient underwent clinical examination revealing a moderate piano key sign (Fig. 1a). The patient reported that his distal clavicle was initially much more prominent, until he self-reduced it by manual pressure. Bilateral anterior posterior (AP) X-ray views of the clavicles were performed without (Fig. 2a) and with 10 kg weights attached to each wrist of the hanging arms (Fig. 2b). In addition, unweighted Alexander X-ray views were obtained from the healthy right (Fig. 3a) and affected left AC joint (Fig. 3b). X-rays confirmed the diagnosis of a Rockwood type V AC joint separation. A magnetic resonance imaging (MRI) of the left shoulder region confirmed a total rupture of the AC and the CC ligaments with a partial rupture of the trapezius muscle fascia (Fig. 4a) and a ruptured AC capsule (Fig. 4b).
Due to the patient’s wishes, the injury was treated conservatively using an AC joint brace (“acromion 2.0”, RO + TEN, Arcore, Italy), that provides a strap system, allowing depression of the clavicle with a broad shoulder pad, while simultaneously elevating the humerus towards the AC joint (Fig. 1b). The AC joint brace was adjusted by an orthopaedic technician one day after the injury and could afterwards be adjusted by the patient independently.
The AC joint brace reduced the AC joint as made evident by radiographic imaging taken one week after the injury (Fig. 2c).
The brace was worn day and night and only taken off for showering and physiotherapy sessions of 40 min/day. Physiotherapy began one week after the injury and was undertaken once or twice a week following a restrictive physiotherapy protocol (Table 1).
During the first week after the injury, the patient reported reoccurring subluxations of the clavicle and a feeling of instability, whenever he took off the brace to shower. These subluxations gradually became less frequent and a more stable feeling of the AC joint was reported. From the second week after the injury onwards, no subluxations reoccurred and the patient reported a return of stability similar to the one before the injury.
The patient was able to return to work two weeks after the injury, still constantly wearing the AC joint brace and mainly performing one-handed computer tasks.
After six weeks of conservative treatment, the AC joint brace was taken off and bilateral AP X-ray views of the clavicles were obtained another three days later. The radiographs showed an aligned AC joint (Fig. 2d) with an anatomic reduction, comparable to the reduction, observed while the patient was still wearing the AC joint brace (Fig. 2c).
The patient reported of muscle soreness of the deltoid muscle and myofascial trigger points in the upper trapezius muscle after taking off the brace. Both symptoms subsided over the coming weeks. The active range of motion one week after removing the brace was 80° of abduction, 80° of flexion, 45° of external rotation and internal rotation to the T12 vertebra level. Within the third week after brace removal, the patient returned to the full pre-injury range of motion with an active abduction of 180°, flexion of 180°, external rotation of 90°, and internal rotation to the T7 vertebra level.
The patient was able to return to sports (running, gym, swimming), four weeks after the AC joint brace was taken off but was instructed not to lift heavy weights with the left upper extremity for another four weeks. Further, the cosmetic result was satisfying and showed no contour changes compared to the contralateral side. (Fig. 1c).
At the six-month follow-up, weighted X-ray views (10 kg) showed an AC joint that had healed in a Rockwood type II position with a slightly elevated clavicle compared to the uninjured contralateral side (Fig. 2e). The patient’s function was at a pre-injury level and especially no signs of scapula dyskinesia were evident.
The Subjective Shoulder Value at the six-month follow-up was 90 (range 0–100) , the Taft Score after the same period of time was 10 (range 0–12)  and the Constant Shoulder Score was 95 for the injured and 100 for the healthy side (range 0–100) .