Clavicular hook plate may induce subacromial shoulder impingement and rotator cuff lesion--dynamic sonographic evaluation

Abstract

Background: Clavicular hook plates are effective fixation devices for distal clavicle fractures and severe acromioclavicular joint dislocations. However, increasing number of studies has revealed that subacromial portion of the hook may induce acromial bony erosion, shoulder impingement, or even rotator cuff damage. By sonographic evaluation, we thus intended to determine whether the presence of hook plate may induce subacromial shoulder impingement and its relationship relative to surrounding subacromial structures.

Methods: We prospectively followed 40 patients with either distal clavicle fracture or acromioclavicular joint dislocation that had surgery using the Arbeitsgemeinschaft für Osteosynthesefragen (AO) clavicular hook plate. All patients were evaluated by monthly clinical and radiographic examinations. Static and dynamic musculoskeletal sonography examinations were performed at final follow-up before implant removal. Clinical results for pain, shoulder function, and range of motion were evaluated using Constant-Murley and Disability of Arm, Shoulder, and Hand (DASH) scores.

Results: Clinically, 15 out of 40 patients (37.5%) presented with subacromial impingement syndrome and their functional scores were poorer than the non-impinged patients. Among them, six patients were noted to have rotator cuff lesion. Acromial erosion caused by hook pressure developed in 20 patients (50%).

Conclusions: We demonstrated by musculoskeletal sonography that clavicular hook plate caused subacromial shoulder impingement and rotator cuff lesion. The data also suggest an association between hardware-induced impingement and poorer functional scores. To our knowledge, the only solution is removal of the implant after bony consolidation/ligamentous healing has taken place. Thus, we advocate the removal of the implant as soon as bony union and/or ligamentous healing is achieved.

Figure 1

Acromial erosion. A 41-year-old man who received hook plate fixation for left AC dislocation. (A) Anteroposterior view of the left shoulder 3 months postoperatively before implant removal showed remarkable acromial osteolysis (arrow). (B) The bony defect was still visible 1 month after implant removal (arrow).

Figure 2

Supraspinatus tendon attrition before and after implants removal. Sonographic findings of a 40-year-old man who had shoulder impingement syndrome before implant removal. (A) A partial thickness tear was noted at the bursal aspect of the supraspinatus tendon (SSP), which resulted from repetitive mechanical attrition by the hook of the plate (arrow). The infraspinatus tendon (ISP) was intact. (B) 1 month after implant removal, the same patient was re-evaluated. Musculoskeletal sonography showed the dimpling lesion had become less obvious than before.

Figure 3

Sonographic findings without shoulder impingement. Dynamic musculoskeletal sonography of a 26-year-old man presented with no clinical impingement sign before implant removal. (A–D) Smooth passage of the supraspinatus (SSP) tendon under the acromion was observed while the shoulder was passively elevated from neutral to 180° of forward elevation. HH, humeral head; AC, acromioclavicular joint.

Figure 4

Sonographic findings with shoulder impingement. Dynamic musculoskeletal sonography of a 36-year-old man developed shoulder impingement syndrome after receiving hook plate fixation of a left distal clavicle fracture. The treated shoulder was passively and forwardly elevated from a neutral position towards 180° elevation. It was stopped at 120° when the patient reported intolerable pain. (A–C) At 90° forward elevations, bunching of supraspinatus tendon fibers (arrowheads) was noted accompanied with distention of the subacromial/subdeltoid bursa (arrow) signifying flowing fluid of bursitis. (D) Another remarkable finding is abnormal superior translation of humeral head with regard to the acromion obstructing its passage beneath the acromion. SSP, supraspinatus tendon; HH, humeral head; AC, acromioclavicular joint.

Figure 5

Subdeltoid fluid and impingement before and after implants removal. A 31-year-old man who received hook plate fixation of a right distal clavicle fracture developed shoulder impingement syndrome. (A) Musculoskeletal sonography revealed subacromial/subdeltoid (SASD) bursitis with flowing fluid before implant removal (arrowhead). (B) Four weeks after implant removal, the same patient was reevaluated. Sonographic finding showed unobstructed passage of the humeral head into the acromion and disappearance of the flowing fluid. SSP, supraspinatus tendon.