Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Diffuse idiopathic skeletal hyperostosis
Key Points
- ■
This chronic, age-related condition is characterized by new bone growth, especially at entheses.
- ■
Radiologic findings are characteristic but may be confused with those of spondyloarthritis.
- ■
Few symptoms are related to diagnostic changes in the thoracic spine.
- ■
There is increased risk of important cervical and lumbar arthropathy, enthesopathy, and neural impingement.
- ■
An association exists with obesity, type 2 diabetes, gout, dyslipidemia, hypertension, hyperinsulinemia, and other features of metabolic syndrome.
- ■
Growth factors, particularly insulin, are implicated in the disorder.
History
Diffuse idiopathic skeletal hyperostosis (DISH), also known as ankylosing hyperostosis or Forestier disease, is a ubiquitous skeletal condition, affecting many species and most human populations studied. Forestier and Rotes-Querol presented comprehensive anatomic, radiologic, and clinical data on the disorder, which was then termed ankylosing hyperostosis . The condition is seen as a well-defined syndrome with both axial and peripheral manifestations. The diffuse nature of the condition later led to the term diffuse idiopathic skeletal hyperostosis .
Epidemiology
There is a 2 : 1 reported male predominance in DISH with the prevalence in both sexes rising with age and weight ; although DISH has been uncommonly reported before the age of 45 years, anecdotal observations indicate a recent trend to a younger age at diagnosis.
Although used criteria vary, population surveys indicate that this is a common condition. In Scandinavia, the incidence is estimated to be 7 per 1000 in men and 4 per 1000 in women beyond the age of 30 years. Prevalence rates vary in different populations but are broadly consistent with these findings. Approximately 10% to 15% of men and 5% to 10% of women older than the age of 65 years have DISH, although some populations (e.g., Pima Indians) have an increased predisposition for the disorder ( Table 206.1 ). Some Asian populations may have lower prevalence rates. It is likely that the prevalence is increasing in some of these populations. The related spinal phenotype of ossification of the posterior longitudinal ligament (OPLL) occurs in up to 4% of Japanese people, some 80 times the rate in Europeans. In patients with OPLL, 25% also have DISH.
Table 206.1
Prevalence of Diffuse Idiopathic Skeletal Hyperostosis a
| Population | Prevalence |
|---|---|
| White populations (various studies) | Men: 10% |
| Women: 8% | |
| Pima Indians | Men: 54% |
| Women: 14% | |
| Men with gout | 58% |
a The table gives the prevalence of diffuse idiopathic skeletal hyperostosis at age 65 years or older (selected studies). Studies in some Asian populations, such as Koreans, suggest a lower prevalence . Diagnostic criteria vary slightly; for instance, the number of bony bridges may vary between 2 and 3.
Criteria and Characteristic Description
Criteria
A number of classification criteria have been used in studies of DISH. The Resnick criteria that require the new bone formation to bridge four contiguous vertebral bodies in the absence of degenerative disk disease and the absence of inflammatory sacroiliac or facet joint changes are the most used ( Fig. 206.1 ). These criteria therefore define DISH unassociated with another spinal disorder. In routine clinical practice, it is more common to see significant age-related disk or facet joint degenerative change occurring in conjunction with changes of DISH. Thus study populations of “pure” criteria-defined DISH may differ in clinical characteristics from DISH when it occurs with other common degenerative spinal conditions or with an inflammatory spondyloarthritis. Classification studies to define earlier stages of DISH are evolving.
![Fig. 206.1, Typical radiographic findings in the thoracic spine on routine chest x-rays (posteroanterior [a] and lateral [b] ), with “flowing” new bone formation linking four contiguous vertebrae, predominantly right sided, in absence of intervertebral disk change.](https://storage.googleapis.com/dl.dentistrykey.com/clinical/Diffuseidiopathicskeletalhyperostosis/0_3s20B9780702081330002066.jpg "Fig. 206.1, Typical radiographic findings in the thoracic spine on routine chest x-rays (posteroanterior [a] and lateral [b] ), with “flowing” new bone formation linking four contiguous vertebrae, predominantly right sided, in absence of intervertebral disk change.")
Characteristic bone changes
The condition is characterized by widespread new bone formation, with an increase in the amount of both normal bone and heterotopic bone formation, and specifically, the presence of new bone growth into the entheseal regions ( Fig. 206.2 ). The enthesis is the region where the tendon, ligament, joint capsule, or annulus fibrosus fibers insert into bone. Although it was the prominent new bone growth in the anterolateral entheseal regions along the thoracic spine that first brought attention to this condition, it may affect any skeletal structure to differing degrees.
![Fig. 206.2, Hand of patient with diffuse idiopathic skeletal hyperostosis demonstrates the full spectrum of bone and entheseal changes in this disorder. Note exostoses ( [a] second and fifth metacarpophalangeal heads), capsule bone ( [b] fourth proximal phalangeal joint), prominent phalangeal enthesopathy ( [c] second and third proximal phalanx), “arrowheading” ( [d] tufts of terminal digits), cortical thickening ( [e] tubular bones), and enlargement of sesamoid bones (f) . The soft tissues and joint spaces are normal. 18](https://storage.googleapis.com/dl.dentistrykey.com/clinical/Diffuseidiopathicskeletalhyperostosis/1_3s20B9780702081330002066.jpg "Fig. 206.2, Hand of patient with diffuse idiopathic skeletal hyperostosis demonstrates the full spectrum of bone and entheseal changes in this disorder. Note exostoses ( [a] second and fifth metacarpophalangeal heads), capsule bone ( [b] fourth proximal phalangeal joint), prominent phalangeal enthesopathy ( [c] second and third proximal phalanx), “arrowheading” ( [d] tufts of terminal digits), cortical thickening ( [e] tubular bones), and enlargement of sesamoid bones (f) . The soft tissues and joint spaces are normal. 18")
Diffuse idiopathic skeletal hyperostosis changes are most characteristic in the thoracic spine, where uninterrupted new bone may “flow” from one vertebra to another ( Fig. 206.3 ). It is more prominent on the right side of the thoracic vertebra. This is thought to be a consequence of the pressure effect of the left-sided aorta ( Fig. 206.4 ). The presence of the anterior longitudinal ligament over the anterior two-thirds of the vertebral bodies dictates the distribution of the new bone formation. There is often a gap in the new bone adjacent to the intervertebral disk or between the new bone and the intact original cortex. When disk changes are absent, the new bone formation may be applied closely to the vertebral bodies and can, at times, mimic axial spondyloarthritis. However, in DISH, the original cortex remains under the ossified ligament; in axial spondyloarthritis, erosion of the cortex is characteristic, particularly at the vertebral corners, with underlying sclerosis being present when inflammation is active. Based on chance alone, DISH may coexist with axial spondyloarthritis or any other condition. In particular, because the condition is more prominent with increased age, it particularly commonly coexists with intervertebral disk change, and in such situations the bulging of the disk material anteriorly may give rise to spectacular anterior spinal hyperostotic change. In the more mobile cervical and lumbar spine regions, hyperostotic changes are more characteristic than simple bridging, and spinal stenosis may result.
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here