Musculoskeletal Complications of Diabetes - Part 2

Feet:
Diabetic osteoarthropathy (also known as Charcot or neuropathic artropathy) is a condition involving destructive, lytic joint changes. It is a severe, destructive form of degenerative arthritis resulting from a loss of sensation (brought on by underlying diabetic neuropathy) in the involved joints. It most commonly affects the pedal bones. Loss of sensation leads to inadvertent (and unnoticed) repeated microtrauma to the joints, which leads to degenerative changes.

The condition is quite rare, affecting only 0.1-0.4% of diabetic patients, and is seen in both type 1 and type 2 diabetes. The average duration of the disease in affected persons is 15 years.

The diagnosis is made based on radiographic findings, with symptoms often milder than would be expected based on the radiographs. There is usually no history of overt trauma.

Depending on the stage and severity of the arthropathy, radiographs can show degenerative changes with subluxation, bone fragments, osteolysis, periosteal reaction, deformity, and/or ankylosis. Computed tomography (CT) scans are insensitive when evaluating for disease activity, whereas magnetic resonance imaging (MRI) and bone scintrigraphy studies are valuable adjuncts to plain films in this regard. The differential diagnosis includes infection, inflammatory process, degenerative process, tumor, deep venous thrombosis or thrombophlebitis, and neuropathic arthropathies secondary to other conditions. Diabetic peripheral neuropathy is thought to play the greatest pathogenic role in diabetic osteoarthropathy.

Treatment is generally conservative and unsatisfactory, involving both splinting/bracing to protect the area from weight bearing, and good glycemic control. Podiatrists sometimes use a total-contact cast for acute Charcot joints. This must be applied by an experienced cast technician, and monitored and changed frequently. Unfortunately, it carries a fairly high risk of causing new injuries and ulcers because of the tight fit and patients' underlying neuropathy. Broad-spectrum emiric antibiotics are also frequently used when skin ulcers accompany the arthropathy.

Muscles:
Diabetic muscle infarction is a rare condition. This spontaneous infarction, with no history of trauma, tends to affect patients with a long history of poorly controlled diabetes. It is most commonly in people with insulin-requiring diabetes, and most affected patients have multiple microvascular complications (neuropathy, nephropathy, and retinopathy).

The clinical presentation is an acute onset of pain and swelling over days to weeks in the affected muscle groups (usually the thigh or calf), along with varying degrees of tenderness.Creatinine phosphokinase levels may be normal or elevated. Otherwise, laboratory investigations are done to exclude other conditions, such as tumor, muscle infection/abscess, thrombophlebitis/thrombosis, localized myositis, or osteomyelitis.

CT scans are nonspecific. MRI may show high signals of the involved muscle on the T2-weighted images.

Incisional muscle biopsy may be needed to confirm the diagnosis. The primary findings on biopsy are muscle edema and necrosis. Excisional muscle biopsy may worsen the condition and should only be done to rule out infection or malignancy.

Therapy consists of rest and analgesia. Routine daily activities are not deleterious to the condition, but physical therapy may cause exacerbation. Spontaneous diabetic muscle infarction tends to resolve over a period of weeks to months in most cases.

Skeleton:
Diffuse idiopathic skeletal hyperostosis (DISH) is characterized by metaplastic calcification of spinal ligaments (diagnosed on lateral spine radiographs) along with osteophyte formation. However, disc spaces, apophyseal joints, and sacroiliac joints are unaffected. The thoracic spine is most commonly affected. It may be accompanied by a more generalized calcification of other extra-axial ligaments and tendons as well.

The underlying pathophysiology is not understood. DISH has a higher prevalence among diabetic patients than among people without diabetes. Specifically, it is commonly seen in association with type 2 diabetes, particularly in obese persons.

Patients complain of stiffness in the neck and back, with decreased range of motion. Pain is generally not a prominent symptom. Treatment consists of physical therapy and NSAIDs or other analgesics. There is no evidence yet that good glycemic control delays the onset or improves this condition.

Osteoarthritis:
Diabetes is not clearly a risk factor for osteoarthritis (OA). However, obesity is a risk factor for both conditions. Several studies have reported an association of early OA and diabetes. Both large and small joint OA have been reported to be increased in type 2 diabetes. However, OA of the weight-bearing joints in the affected type 2 diabetic patients may be related to their obesity and not to the diabetes itself. It is not yet known whether diabetes is a risk factor for OA independent of obesity.

Conclusion:
Diabetes quite commonly affects the musculoskeletal system, resulting in significant morbidity. These manifestations may go unrecognized or simply be overlooked in daily clinical practice. However, many of these rheumatological complications are treatable (to varying degrees), with resultant improvements in quality of life and more independence in activities of daily living. Thus, physicians should be aware of the possible musculoskeletal complications of diabetes in order to intervene and provide the best care for affected patients. Asking patients about their symptoms and monitoring for signs of musculoskeletal complications can be an invaluable part of overall diabetes care. Make sure you share your concerns about any symptoms you may have.

BSP