Distal clavicular fracture is a common traumatic injury. Given the high rates of non-union after non-operative treatment, it is recommended that clavicular fractures of Neer type II are treated surgically due to their unstable nature. The clavicular hook plate is one of the recommended devices for treating distal clavicular fractures. The clavicle hook plate works according to the principle of leverage, where the distal part is designed as a hook that is placed beneath the acromion, and the proximal portion is designed as a plate. Although it is easy to manipulate the hook plate during surgery, which is associated with excellent functional outcomes for the shoulders, the high complication rate of 40.7% is problematic. The complications caused by the hook under the acromion are common and include acromial osteolysis, acromioclavicular joint arthrosis, subacromial impingement, and rotator cuff injury. Many authors have discussed these complications, and some of them are considered to be associated with highly concentrated subacromial stress. However, clavicular midshaft fractures on another stress concentration point are rarely reported or investigated due to their lower incidence.

To identify and analyze the potential risk factors of clavicular midshaft fractures after hook plate fixation to treat Neer type II clavicular fractures.

From March 2009 to July 2019, 294 patients treated with hook plates for distal clavicular fractures met the inclusion criteria during the period. The study sample comprised 279 patients without clavicular midshaft fractures (control group) and 15 patients with clavicular midshaft fractures (complication group) . Data collection included gender, age, affected side, body mass index, smoking status, type of medial screw used, whether the surgery was performed by a resident, whether the hook plate was bent during the surgery, number of holes in the plate, depth of the hook, and the time and causes of this complication. The Chi-square test was used to compare all potential risk factors between the two groups. Only a statistically significant predictive variable was included in the final logistic regression.

Older patients with distal clavicular fracture treated with hook plate are more likely to develop clavicular midshaft fractures (OR= 3.478; 95% CI : 1.719-15.407; P= 0.003) .

The risk of clavicular midshaft fracture after hook plate fixation could be significantly increased by advanced age.