• You could have undetected shoulder problems."My ruptured tendon" is Copyrighted by Flickr user: juhansonin (Juhan Sonin) under the Creative Commons Attribution license.
  
  

Your Shoulder---the Mechanics

• You shoulder is made of three bones---the upper arm, shoulder blade and the collarbone---and is a ball-and-socket joint. The ball, at the top end of the bone, fits into the small socket of the shoulder blade. This forms the shoulder joint, also called the glenohumeral joint. The socket is surrounded by soft tissue. A durable and smooth surface is located on the top of the arm bone, but it's the thin, inner lining of the joint that allows the shoulder to move.
  
  

Possible Complications

• It's normal to experience some tenderness, stiffness or pain shortly after either type of surgery. However, complications of shoulder surgery can include increasing pain or swelling, a wound infection, unusual bleeding, and numbness or tingling of the arm or hand. You may also run a fever the day after the surgery.
  
  

Surgery Failure Reasons

• Shoulder surgery failures arise when the extent of your shoulder problem is not adequately diagnosed or discovered. Although your surgeon knows what's wrong with your shoulder, there can be additional problems with your shoulder, like a rotator-cuff injury, that are not uncovered in the initial diagnosis. According to eOrthopod, there is more than one problem present in 84 percent of all surgery failures. If those issues aren't identified and repaired during the initial surgery, you're at risk for a failed procedure and possible additional surgeries.
  
  

Hardware Problems

• Another problem that can arise during shoulder surgery involves the "hardware" that the surgeon uses, like anchors, to keep the shoulder together. For instance, if hardware is placed in the wrong place, it can cause three problems: soft-tissue damage, the bearing down of your bone or osteoarthritis.
  
  

Undetected Bone Loss

• During your original shoulder surgery, your surgeon may not realize the extent of bone loss in the area. If you have a severe amount of boss loss, open surgery and bone grafting could be necessary. If this isn't done, the humeral head in the socket will constantly pop out during forward movements or motions. This is also known as chronic anterior dislocations.