Shoulder pain after a hand injury is common. Weakness can occur when there is pain but this usually means hand pain leads to hand and wrist weakness, not shoulder weakness.
A study was done at a large medical facility in Texas to find out how many patients with wrist or hand pain have weak shoulder muscles. Grip strength was measured. Separate tests were given for each muscle around the shoulder.
The study showed rotator cuff weakness in patients with hand and/or wrist injuries. It’s not clear if the hand injury leads to disuse of the limb and deconditioning as the cause
of the weakness. More studies are needed to see if the shoulder pain is caused by injury to the hand or wrist.