The hook plate is a very powerful way of holding the clavicle reduced to the correct level alongside the acromion. The problem with the hook plate is it requires removal at a later date as the hook under the acromion can cause problems with the tendons of the shoulder and with time can erode through the bone of the acromion.
Hence it means 2 operations, one to insert and one to remove.
The hook under the acromion may also limit arm movement above shoulder height till it is removed. The timing of removal is around 3 months following insertion. The clavicle may pop back up after removal if removed prior to sound ligament healing.