Peri-implant Fractures Following Hook Plate Fixation for Unstable Distal Clavicle Fractures.

Clavicle hook plate is a common implant for treating distal clavicle fracture. Although high bone union rate and good functional outcome have been reported, so have several complications, such as osteolysis and fracture of the acromion, loss reduction, hook impingement, and rotator cuff tear. Peri-implant fracture over the medial side of the hook plate is a rare complication. Sporadic cases have been reported, and most of them have had no history of trauma. Between June 2015 and August 2018, 7 patients treated for distal clavicle fracture with a 3.5-mm locking compression hook plate with no history of trauma experienced peri-implant fracture of the medial clavicle. This complication occurred at a mean of 29 days. The incidence rate was 9.8%. Peri-implant fracture following hook plate fixation for distal clavicle fracture was not rare. Small hook angle, prolonged retention of the implant, an eccentric medial screw, high plate screw density, and small clavicle diameter may be risk factors for peri-implant fracture. Regarding treatment, 2 patients chose fracture revision with a distal clavicle locking plate and 5 patients chose conservative treatment. All patients achieved bone union at fracture sites. Surgical and conservative management of peri-implant fracture can achieve good functional outcome. [Orthopedics. 2020;43(x);xx-xx.].