Diffuse Idiopathic Skeletal Hyperostosis

Diffuse idiopathic skeletal hyperostosis also called Forestier’s disease is characterized by unique, flowing (wave-like in shape) calcification along the sides of the vertebrae of the spine. It is also commonly associated with inflammation and calcification of tendons at their attachments points to bone, a condition called enthesitis. Enthesitis can frequently lead to bone spurs such as heel spurs.

Usually, the disease occurs after the fifth decade of life.

Almost all affected individuals have thoracic involvement. Lumbar vertebrae involvement is  in 68-90% of these persons, and cervical vertebrae in 65-78% of affected individuals.

The facet joint and sacroiliac joints are not involved in diffuse idiopathic skeletal hyperostosis.

Apart from ligaments, tendon, and joint capsule (enthesial) insertions.

Diffuse idiopathic skeletal hyperostosis is present in approximately 19% of men and 4% of women older than 50 years. Below that age, the condition is rare.

Many represent a believe phenomenon rather than a disease. In fact, one study claimed diffuse idiopathic skeletal hyperostosis to be protective against back pain.

Cause of Diffuse Idiopathic Skeletal Hyperostosis

At present no cause is known.

Diagnostic Criteria of Diffuse Idiopathic Skeletal Hyperostosis

• Flowing calcifications and ossifications along the anterolateral aspect of at least 4 contiguous vertebral bodies, with or without osteophytes
• Preservation of disc height in the involved areas and an absence of excessive disc disease
• Absence of bony ankylosis of facet joints and absence of sacroiliac erosion, sclerosis, or bony fusion.

Unlike ankylosing spondylitis, Diffuse idiopathic skeletal hyperostosis does not involve the sacroiliac joint.

Most commonly involved spine is lower thoracic spine involvement which is also is typical of Diffuse idiopathic skeletal hyperostosis, but the lumbar and cervical spine also can be affected. The right side of spine is more commonly involved. The lesser involvement of left side of spine is attributed to pulsation of aorta on this side.

Presentation of Diffuse Idiopathic Skeletal Hyperostosis

Diffuse idiopathic skeletal hyperostosis is a completely asymptomatic phenomenon.

The condition is discovered inadvertently. Rarely, dysphagia may result, either from neuropathy or from physical impingement by bony overgrowth.

If vertebral fusion is quite extensive, reduction in the range of spinal motion occurs but that is extremely rare.

Lab Studies

No laboratory tests are indicated.

Imaging for Diffuse Idiopathic Skeletal Hyperostosis

Radiograph of the thoracic and lumbar spine is usually enough to make a diagnosis. Computed tomography may be performed to evaluate complications, such as fracture, or to conform pressure effects on the trachea, esophagus, and veins.

Radiographs demonstrate typical changes in spine as discussed earlier in this article. Other findings in other regions may be

• Ossification of the nuchal ligaments in skull
• Enthesopathy at the ischial tuberosities, ossification of the sacrotuberous ligament and symphysis pubis in pelvis
• Ossification of the quadriceps and infrapatellar tendons
• Ossification of the Achilles tendon and the plantar aponeurosis
• Ossification of the triceps tendon
• Subcutaneous calcification

There is no associated threat to any internal organs with this disorder.

and the intervening intervertebral disk space is preserved.

There is ligamentous ossification is more prominent on the right lateral aspect of the spine.  Absence on one side of the thoracic spine is thought to be due to the influence of aortic pulsations.

Recognition of diffuse idiopathic skeletal hyperostosis facilitated by its separation from the body of the vertebrae. This gives rise radiologically to the appearance of a radiodense line paralleling the longitudinal axis of the spine but separated by a clearly definable space.

Ossification at sites of the tendon, ligamentous, or joint capsule insertion (enthesitis) is strongly suggestive of the diagnosis. Enthesial reaction at the iliac crest and ischial tuberosities, quadriceps insertion, metacarpal, and phalangeal capsule insertion may be present.

Treatment

There is no specific treatment and the patients are treated symptomatically with anti-inflammatory drugs, local heat, and physical therapy. Any complication is treated accordingly.

Complications

Overgrowth of ligamentous calcification could impinge on other structures but this is quite rare. Posterior longitudinal ligament ossifications may impinge on the spinal cord on rare occasions. Reduced vertebral column flexibility predisposes to vertebral fracture.  Diffuse idiopathic skeletal hyperostosis is not a source of morbidity or mortality.