Relationship Between Subacromial Bone Erosion and Hook Position of Clavicular Plate in Distal Clavicle Fractures.

Objectives: To evaluate the influence of posterior hook position on subacromial bone erosion during surgical treatment of distal clavicle fractures with locking compression plate clavicle hook plate (CHP).

Design: Single-center retrospective study.

Setting: Level V trauma center (university hospital).

Patients: Twenty-one patients (mean age, 45.8 years) treated with CHP were included. One, 3, 15, and 2 patients had Neer type I, IIa, IIb, and V fractures, respectively.

Intervention: Open reduction and internal fixation were performed with locking compression plate CHP. All implants were removed after a mean of 6.1 months postoperatively.

Main Outcome Measurements: Japanese Orthopaedic Association shoulder scores were used to assess recovery. Radiographically, the coracoclavicular distance was measured as the distance between the tip of the coracoid process and the undersurface of the clavicle. Three-dimensional computed tomography was performed to identify bone erosion at the hook tips after implant removal. The distance from the acromioclavicular joint center to the bone erosion was divided into 5 areas at 5-mm intervals, and the position and depth of bone erosion were measured in each area.

Results: The mean follow-up period was 17.4 months; mean ± SD Japanese Orthopaedic Association score was 75.9 ± 4.7 at the final follow-up, whereas the mean duration of bony union was 4.4 ± 1.0 (SD) months. Delayed bony union was observed in one patient, whereas a second surgery was required in another due to acromion cut-out. Radiography showed overreduction in 95% of cases. The correlation coefficient showed a difference between coracoclavicular distance and the position of bone erosion measured by CT (Rs = 0.32, P = 0.006). Erosion under the acromion surface was found in all patients. The depth of erosion correlated with the posterior hook position (Rs = 0.29, P = 0.023).

Conclusions: Posterior hook tip placement increased the likelihood of bone erosion and complications due to overreduction. CHP should be set more anteriorly beneath the acromion to prevent complications.

Level Of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.