Diabetes and shoulder disorders

Musculoskeletal disease is one of the most common complications in patients with diabetes, and yet is receives relatively little attention. The severity and the risks of musculoskeletal complications might not be well recognized as cardiovascular complications; however, the associated ailments certainly inflict both physical and psychological harm on people with diabetes. Among the various musculoskeletal diseases, shoulder pain is one of the most common complaints. In general, it is characterized by pain and limited range of motion of one or both shoulders. Shoulder pain not only causes decreased quality of life, but also leads to disability in daily activities, and might interfere directly or indirectly with control of metabolic processes. Previous reports showed that there is a higher prevalence rate (27.5%) of shoulder disorders in patients with diabetes as compared with the rate of 5.0% found in general medical patients. Two of the most common shoulder disorders are frozen shoulder, also known as ‘adhesive capsulitis’ and rotator cuff disease. Frozen shoulder is characterized by progressive pain, stiffness, limited active and passive range of motion of the shoulder joints, especially external rotation, and night pain. Although the exact causes of frozen shoulder are still underexplored, it is generally believed that frozen shoulder develops as a result of perivascular inflammation and fibroblastic proliferation, followed by capsular fibrosis and contracture. It is worth noting that primary frozen shoulder is idiopathic and secondary frozen shoulder might be associated with previous shoulder injury, such as rotator cuff injury, trauma or prolonged immobilization. Clinically, frozen shoulder is diagnosed by history and physical examination. Current available managements include use of analgesia, such as non-steroidal anti-inflammatory drugs (NSAIDs) or paracetamol and/or intra-articular steroid injection, and can be combined with local anesthetic applications. Encouragement of activity is also crucial. Once the symptoms of pain and inflammation have reduced, gentle stretching and exercises that enhance the range of motion should be encouraged. In rare cases, surgical procedures can be considered, such as manipulation under anesthesia or capsular release under arthroscopic guidance. The rotator cuff consists of the supraspinatus, infraspinatus, teres minor and subscapularis muscles. It originates from the scapula, and forms tendons that cover the humeral head. The rotator cuff provides important dynamic motor control and stability of the shoulder joint. Known risk factors of rotator cuff disease include old age, abnormal shoulder structure, certain sports and occupations that require excessive overhead activities. Rotator cuff disorders range from simple inflammation to complete tendon tears, most frequently involving the supraspinatus tendon. The symptoms include shoulder pain, decreased muscle strength and particularly limited active range of motion. Clinically, taking a detailed history plus physical examination can help with the diagnosis. Imaging studies, such as ultrasound and magnetic resonance imaging, can confirm the diagnosis and provide further information of the severity and the extent of rotator cuff disease. Conventional radiograph is also helpful for making a more advanced differential diagnosis, and for ruling out bony abnormalities and tendon calcification. Management of rotator cuff disease includes NSAIDs, steroid injection, stretching and strengthening exercises for the shoulder. Surgical repair might be required in severe cases, such as complete tear of rotator cuff. The association between rotator cuff disease and diabetes has yielded inconsistent results. To investigate the effect of diabetes on the occurrence of rotator cuff disorder, we analyzed nationwide data from the National Health Insurance Research Database in Taiwan. A total of 498,678 participants, including 28,391 diagnosed with diabetes and 25,621 with hyperlipidemia in the year 2000, were followed for an 11-year period. Multivariate Cox proportional hazards models were used to explore the effect of: (i) diabetes; (ii) hyperlipidemia; (iii) diabetes with/ without insulin use; and (iv) hyperlipidemia with/without statin use on the development of rotator cuff diseases. We found that, during the follow-up period, 26,664 patients developed rotator cuff diseases with a crude hazard ratio (HR) of 2.11 for patients with diabetes as compared with those without diabetes (95% confidence interval [CI] 2.02–2.20, P < 0.0001). The crude HR for rotator cuff disease in patients with hyperlipidemia as compared with those without hyperlipidemia was 2.00 (95% CI 1.92–2.08, P < 0.0001). The results of multivariate Cox proportional hazards analysis showed that, in addition to older age and female sex, both diabetes and hyperlipidemia increased the risk of rotator cuff diseases (diabetes HR 1.47, 95% CI 1.41– 1.54, P < 0.0001; hyperlipidemia HR 1.48, 95% CI 1.42–1.55, P < 0.0001). We also found that the elevated risk still existed in patients with diabetes with/without insulin use (diabetes with insulin use HR 1.43, 95% CI 1.35–1.51, P < 0.0001; diabetes without insulin use HR 1.64, 95% CI 1.53–1.75, P < 0.0001). Our findings confirmed that patients with diabetes, regardless of insulin use, had a higher risk of developing rotator cuff diseases. Our findings are in accord with previous imaging studies showing that degenerative changes of rotator cuff tendon were more commonly observed by sonography in patients with diabetes than in controls.