Diffuse idiopathic skeletal hyperostosis, commonly called DISH or Forestier’s disease, is a condition where ligaments and tendons along the spine gradually harden into bone. It affects roughly 19% of men and 4% of women over age 50, making it surprisingly common yet often undiagnosed. The condition primarily targets the thoracic (mid-back) spine but can involve the neck, lower back, and joints throughout the body.
How DISH Develops
In a healthy spine, ligaments are flexible bands of tissue that connect vertebrae and allow movement. In DISH, stem cells in these ligaments begin behaving abnormally. Instead of maintaining ligament tissue, they transform into bone-forming cells. Several growth signals drive this process, including insulin-like growth factor, which stimulates these stem cells to build bone where it shouldn’t exist. Over time, thick bony deposits form along the front and sides of the spine, sometimes reaching up to 2 centimeters thick, fusing vertebrae together.
One curious anatomical detail: in the thoracic spine, the bony growth tends to appear on the right side rather than the left. Researchers believe the pulsing of the aorta, the body’s largest artery running along the left side of the spine, actually inhibits bone formation on that side.
The exact trigger remains unknown, which is where the “idiopathic” in the name comes from. But the condition is strongly linked to metabolic factors, particularly obesity, type 2 diabetes, and metabolic syndrome. Hyperinsulinemia, a state of chronically elevated insulin, appears to play a direct role. Insulin and insulin-like growth factor have anabolic (tissue-building) effects that may fuel the excess bone formation. People with DISH also tend to have higher body weight, higher BMI, and more visceral fat (the deep abdominal fat surrounding organs) compared to those without the condition.
Who Gets DISH
DISH overwhelmingly favors older men. In a U.S. community study of adults averaging 71.5 years old, 25.6% of men had DISH compared to 5.5% of women. Prevalence climbs steeply with age. In one study, only about 1% of people in their 40s had the condition, but that rose to 13.6% among those over 70. A Finnish study found similar patterns: 11.2% of men and 6.9% of women over 70 showed signs of DISH on imaging. People with hypertension, obstructive sleep apnea, and smoking history are also more likely to have it.
Symptoms and What DISH Feels Like
Many people with DISH have no symptoms at all and only discover the condition incidentally when getting an X-ray for something else. When symptoms do appear, they typically include stiffness and aching in the upper or mid-back, especially in the morning or after periods of inactivity. The stiffness tends to be the most bothersome feature, as the fused vertebrae progressively limit spinal flexibility.
When DISH affects the cervical (neck) spine, it can cause more significant problems. Bony growths projecting from the front of the neck vertebrae can press on the esophagus and airway. Dysphagia, or difficulty swallowing, is the most common complication of cervical DISH. In rare cases, the bony overgrowth causes voice changes or even breathing difficulties through direct mechanical obstruction, chronic inflammation, or vocal cord paralysis. About 6% of patients in one review required a tracheotomy for acute airway obstruction.
DISH can also cause problems outside the spine. Bony spurs at tendon and ligament attachment points (called enthesopathies) can develop at the heels, elbows, knees, and shoulders, causing localized pain and tenderness. The stiffened spine also carries a hidden risk: because the fused segments can’t flex to absorb impact, the spine becomes more brittle. Even minor falls can cause fractures that would not normally injure a flexible spine.
How DISH Is Diagnosed
Diagnosis is based on imaging, typically plain X-rays. The most widely used standard, established by Resnick and Niwayama, requires three features: flowing bony bridges connecting at least four consecutive vertebral bodies, preserved disc height without significant disc degeneration, and no erosion or fusion of the sacroiliac joints or the small joints at the back of the spine. An alternative set of criteria lowers the threshold to three consecutive vertebral bodies but adds the requirement of bony changes at peripheral tendon attachment sites, aiming to catch the condition earlier.
These criteria matter because they help distinguish DISH from other conditions that stiffen the spine, particularly ankylosing spondylitis. The two can look similar on casual inspection, but the differences on imaging are distinct.
How DISH Differs From Ankylosing Spondylitis
Ankylosing spondylitis is an inflammatory autoimmune condition that primarily affects younger adults and almost always involves the sacroiliac joints (where the spine meets the pelvis). DISH does not erode or fuse the sacroiliac joints in the way ankylosing spondylitis does, though some asymmetric bony bridging can occur around the outer portion of these joints.
The pattern of spinal fusion also looks different on X-rays. DISH produces thick, flowing sheets of bone along the front and sides of the vertebral bodies. Ankylosing spondylitis produces thin, vertical bony bridges called syndesmophytes that form at the outer edge of the spinal discs. The distinction is clinically important because ankylosing spondylitis requires immunosuppressive treatment, while DISH does not.
Treatment and Daily Management
There is no treatment that reverses the bony growth in DISH, so management focuses on controlling symptoms and maintaining mobility. For pain, over-the-counter options like acetaminophen or ibuprofen are the typical first step. These work well for most people with mild to moderate discomfort.
Physical therapy plays a central role. A structured program of mobility, strengthening, and stretching exercises performed daily can reduce back pain and improve spinal range of motion. One study followed 15 patients through a 24-week daily exercise program and found meaningful improvements in pain, flexibility, and disability scores. Bracing can also help relieve symptoms, though outcomes depend heavily on how consistently the brace is worn.
Because of the strong metabolic link, managing weight, blood sugar, and related conditions may help slow progression, though direct evidence for this is still limited. Dietary modifications are generally recommended alongside exercise as part of the overall management plan. For people with cervical DISH causing swallowing or breathing problems, surgical removal of the bony overgrowth is sometimes necessary, though this is uncommon.
Most people with DISH live with manageable stiffness and occasional discomfort rather than severe disability. The main practical concern over time is the gradual loss of spinal flexibility and the increased fracture risk that comes with it, making fall prevention especially important as the condition progresses.