The shoulder is the most mobile joint in the body and because of its extensive range of motion it's susceptible to injury and pain [1]. While the shoulder is not thought of as a weight bearing joint, once you lift an object or roll over at night, the forces going through the shoulder joint exceed those of most joints due to the long lever arm of the outstretched arm [2]. The shoulder can hurt after it has been injured or for no apparent reason. Most shoulder problems are relatively short-lived but sometimes the pain is indicative of a more complex issue.
Here's a guide to what might be wrong and whether or not it's a cause for concern.
No worries:
Slight pain with elevation and when playing overhead sports is common. The four tendons that make up the rotator cuff and the biceps tendon, (the combined musculature that drives the shoulder motions) can be inflamed by activities such as throwing, shooting basketballs, and lifting bags over head [3]. The tendons are covered by a thin layer called a bursa, which swells when irritated. The bursitis is filled with inflammatory components that irritate the nerve fibers sending pain signals to the brain [4,5]. Eliminating the overhead activities and mild use of anti-inflammatories usually cures the mild bursitis, or tendonitis, and solves the problem [6]. Exercises to strengthen posture are also commonly used by our physical therapists to fix mild shoulder irritations. Slumping at your desk, reaching for your mouse, hunching over your keyboard, can all put extra strain on the shoulder, neck or back and may be the cause of your shoulder pain. Stand with your shoulders at or behind your hips with your belly button tucked in and notice the difference.
More worry:
Pain that does not go away or pain that occurs with every activity indicates that the key tissues are irritated enough that they are sending pain signals even without motion [5]. This degree of inflammation precedes more structural injuries such as tears of the tissue or early arthritis. Treated fully, the tears and the arthritis can be prevented. The treatments are often injections of growth factors from platelets, and lubricating fluid called hyaluronic acid [7]. Physical therapy focuses on shoulder mechanics and muscle strengthening, and sports specific training to help fix the activity that might be causing the injury. Often we see throwers with slight errors in their throwing mechanics or golfers with swing abnormalities that bring on the problems, and correction of the swing fixes the pain [8]. We avoid cortisone as there is clear evidence that it weakens the tissues of the shoulder if used too frequently [9,10,11].
Real worry:
Pain at night or pain not improving with therapy after 4 weeks are red flags. Pain radiating down the arm or up to the neck or to the back are also worrisome for injuries not just in the shoulder but sometimes of the neck. These injuries need to be worked up with careful physical exams, x-rays and MRIs. A full tear of the rotator cuff often will present with night pain, since when you roll over you push the arm up into the socket through the rotator cuff tear. Pain radiating down the arm or up to the neck can sometimes be from the discs in the neck or the nerves at the front of the shoulder called the brachial plexus [12]. Instability of the shoulder, with the shoulder popping in or out of the joint is another area that is best treated with early repair of the torn ligaments.
Fortunately most of the torn tissue problems in the shoulder can be repaired under a local block with an arthroscope as an outpatient procedure. Only the severe arthritis cases require bionic replacement. The biologic treatments of anabolic stimulation of the tissues with injections, exercise, physical therapy and activity coaching are becoming more effective, more targeted and more widespread. The key is to treat them early before full tearing of tissues leads to disability.
Our shoulder self-diagnosis tool has more details on symptoms and possible conditions.
References
1. Van der Hoeven, H., & Kibler, W. B. (2006). Shoulder injuries in tennis players.British journal of sports medicine, 40(5), 435-440.
2. Uhl, T. L., Carver, T. J., Mattacola, C. G., Mair, S. D., & Nitz, A. J. (2003). Shoulder musculature activation during upper extremity weight-bearing exercise. Journal of Orthopaedic & Sports Physical Therapy, 33(3), 109-117.
3. Silverstein, B. A., Viikari-Juntura, E., Fan, Z. J., Bonauto, D. K., Bao, S., & Smith, C. (2006). Natural course of nontraumatic rotator cuff tendinitis and shoulder symptoms in a working population. Scandinavian journal of work, environment & health, 99-108.
4. Voloshin, I., Gelinas, J., Maloney, M. D., O'Keefe, R. J., Bigliani, L. U., & Blaine, T. A. (2005). Proinflammatory cytokines and metalloproteases are expressed in the subacromial bursa in patients with rotator cuff disease. Arthroscopy: The Journal of Arthroscopic & Related Surgery, 21(9), 1076-e1.
5. Lewis, J. S. (2008). Rotator cuff tendinopathy: A review. British journal of sports medicine.
6. Blaine, T. A., Kim, Y. S., Voloshin, I., Chen, D., Murakami, K., Chang, S. S., ... & Bigliani, L. U. (2005). The molecular pathophysiology of subacromial bursitis in rotator cuff disease. Journal of shoulder and elbow surgery, 14(1), S84-S89.
7. Mitsui, Y., Gotoh, M., Nakama, K., Yamada, T., Higuchi, F., & Nagata, K. (2008). Hyaluronic acid inhibits mRNA expression of proinflammatory cytokines and cyclooxygenase‐2/prostaglandin E2 production via CD44 in interleukin‐1‐stimulated subacromial synovial fibroblasts from patients with rotator cuff disease. Journal of Orthopaedic Research, 26(7), 1032-1037.
8. Kim, D. H., Millett, P. J., Warner, J. J., & Jobe, F. W. (2004). Shoulder injuries in golf. The American journal of sports medicine, 32(5), 1324-1330.
9. Tillander, B., Franzén, L. E., Karlsson, M. H., & Norlin, R. (1999). Effect of steroid injections on the rotator cuff: an experimental study in rats. Journal of shoulder and elbow surgery, 8(3), 271-274.
10. Wei, A. S., Callaci, J. J., Juknelis, D., Marra, G., Tonino, P., Freedman, K. B., & Wezeman, F. H. (2006). The effect of corticosteroid on collagen expression in injured rotator cuff tendon. The Journal of Bone & Joint Surgery, 88(6), 1331-1338.
11. Akpinar, S., Hersekli, M. A., Demirors, H., Tandogan, R. N., & Kayaselcuk, F. (2002). Effects of methylprednisolone and betamethasone injections on the rotator cuff: an experimental study in rats. Advances in therapy, 19(4), 194-201.
12. Parry, C. W. (1980). Pain in avulsion lesions of the brachial plexus. Pain, 9(1), 41-53.