Hook plate fixation for distal clavicle and acromioclavicular joint injuries: Insights into peri-implant fracture risk.

BackgroundDistal clavicle fractures and acromioclavicular joint dislocations frequently require surgical stabilization, and hook plate fixation is widely used but can be complicated by peri-implant fractures. This study aimed to evaluate patient, anatomical, and implant-related factors associated with peri-implant fractures after hook plate fixation for these injuries.MethodsA retrospective cohort study was conducted at a single tertiary center including adults who underwent open reduction and internal fixation with a pre-contoured clavicle hook plate for distal clavicle fractures or acromioclavicular joint dislocations between October 2013 and November 2023. Demographic data, implant characteristics, and radiographic parameters (clavicle diameter, clavicle length, plate diameter, plate length, and their ratios) were collected. Patients with and without peri-implant fracture were compared using univariable statistical tests, and exploratory univariable logistic regression was performed to estimate associations between selected variables and peri-implant fracture.ResultsAmong 282 patients, 9 (3%) developed peri-implant fractures after hook plate fixation. Patients with peri-implant fractures were older, shorter, and had lower body weight than those without fractures. The peri-implant fracture group also showed a smaller clavicle-to-plate diameter ratio, a higher plate-to-clavicle length ratio, and more frequent use of plates with a greater number of holes, indicating relatively thinner clavicles and disproportionately longer plates.ConclusionsPeri-implant fractures after hook plate fixation for distal clavicle fractures and acromioclavicular joint dislocations were uncommon in this cohort but were associated with older age, smaller skeletal build, longer plates, and poor dimensional matching between the clavicle and plate. Careful assessment of clavicle morphology and judicious selection of plate length may help reduce stress concentration at the medial plate end and lower the risk of peri-implant fracture.