I am a 38-year-old avid tennis player. Two years ago I fell directly on the corner of my shoulder. I was told that I had a second-degree separation of my shoulder and that no surgery was required. The initial pain on the top of my shoulder subsided. However, overhead movement causes deep pain in the shoulder and on the side of my upper arm. Did my original injury heal?

The original injury, which you describe as a ''separated shoulder,'' relates to the acromion (shoulder blade) and clavicular (collarbone) joint. This is one of the four joints that make up the shoulder complex. The acromion-clavicular joint is commonly referred to as the AC joint. The AC joint is most commonly injured from a direct blow to the tip of the shoulder. The degree of AC-joint injury can be determined by an X-ray. The second-degree separation means that the supporting joint capsule has been disrupted and the ligaments have been stretched. This allows the collarbone to elevate in relation to the shoulder blade. A slight bump on the top of the shoulder blade results and widening of the joint space occurs. Both of these findings can be noted on X-ray examination.
Second-degree separations of the AC joint are treated with short-term use of a sling and ice followed by early range of motion and strengthening exercises. The joint eventually heals in this position. Since your pain is not on top of the shoulder, near the AC joint, your source of pain may be coming from the underlying rotator-cuff tendon and/or bursal tissue. Studies report a 5 percent to 15 percent incidence of associated rotator-cuff injury and/or pain, which is elicited when the arm is raised into an overhead position. The pain is a result of the bursal tissue and rotator-cuff tendon being squeezed between the shoulder blade and the arm. Injury to the AC joint has the potential for narrowing the space where the bursal tissue and the rotator-cuff tendon move to and from between these bones (acromion and humerus) with overhead movements. Rotator-cuff tendon tear and pain could co-exist in the shoulder after AC-joint injury. Often a physical examination can identify these problems in the shoulder. In some instances, an MRI is required to assist in making the diagnosis.