It's hard to say. Sometimes the position you're in on the operating table can leave a patient stiff or sore. For a cervical spine fusion you can be placed in one of three positions. You may be face up, face down, or on your side.
In the case of a posterior cervical fusion you're face down. The arms may be held in place with tape. Weights may be used to pull the arms away from the spine. This helps hold the arms and gives the doctor better access to the surgical site.
Some fusions are done from the side. This gives the doctor room to reach the side and part of the back of the neck. In a neck fusion operation you can end up with afterward pain if your arms are positioned in one place too long. The same thing can happen if your arms aren't fully supported.
Be sure and talk to your doctor if your symptoms don't go away in a few days. Finding and fixing problems early can prevent complications.