High-yield overview
Flowing Anterior Ossification | The 'Rigid Spine' That Fractures From a Trivial Fall
All 3Resnick Criteria Needed
4+Contiguous Levels
T7-T11Right-Sided Thoracic Peak
2:1Male:Female
Resnick & Niwayama Criteria (all three required)
Flowing ossification
PatternContinuous ossification along the anterolateral aspect of at least 4 contiguous vertebral bodies
TreatmentHallmark
Preserved disc height
PatternRelative preservation of disc space without large degenerative changes at involved levels
TreatmentRules out spondylosis
No SI/facet fusion
PatternAbsence of sacroiliac joint erosion/fusion and apophyseal (facet) joint ankylosis
TreatmentRules out AS
Critical Must-Knows
- DISH is a non-inflammatory enthesopathy: new bone forms at ligaments/entheses, classically the anterior longitudinal ligament.
- Diagnosis is RADIOGRAPHIC (Resnick): flowing ossification over 4+ levels, PRESERVED discs, and SPARED SI/facet joints.
- It is NOT ankylosing spondylitis: DISH spares the SI joints, is HLA-B27 negative, and is non-inflammatory.
- The exam danger: an ankylosed DISH spine behaves like a long bone and fractures (usually transverse, extension-type) from low-energy trauma.
- These fractures are highly unstable, easily missed on plain films, and carry high rates of spinal cord injury and mortality.
Clinical Pearls
- "Strongly associated with type 2 diabetes, obesity, and the metabolic syndrome.
- "Right-sided thoracic predominance is attributed to the pulsatile descending aorta inhibiting left-sided ossification.
- "Anterior cervical osteophytes are a classic cause of mechanical dysphagia (Forestier dysphagia).
- "In any rigid spine with new pain after a minor fall, assume a fracture until CT proves otherwise.
The Three Traps That Catch Candidates
At a Glance
DISH versus Its Two Great Mimics
| Feature | DISH (Forestier) | Ankylosing Spondylitis | Spondylosis (degenerative) |
|---|---|---|---|
| Mechanism | Non-inflammatory enthesopathy/ossification | Inflammatory (HLA-B27, axial spondyloarthritis) | Degenerative disc/facet disease |
| Disc height | Preserved at involved levels | Preserved early, then fuses | Reduced (disc degeneration) |
| SI joints | Spared (key rule) | Eroded then fused | Normal or degenerative |
| Ossification shape | Bulky, flowing, anterolateral ('candle wax') | Thin vertical syndesmophytes (bamboo) | Discrete horizontal osteophytes |
| Typical patient | Older, male, diabetic/obese | Younger, inflammatory back pain | Older, mechanical pain |
Clinical Imaging
Mnemonics
Mnemonic
FDSResnick Diagnostic Criteria
| F | Flowing Flowing ossification over 4 or more contiguous vertebral bodies |
| D | Discs Disc heights relatively Preserved (so not degenerative spondylosis) |
| S | Spared joints SI joints and facet (apophyseal) joints Spared (so not ankylosing spondylitis) |
| F | Flowing Flowing ossification over 4 or more contiguous vertebral bodies |
| D | Discs Disc heights relatively Preserved (so not degenerative spondylosis) |
| S | Spared joints SI joints and facet (apophyseal) joints Spared (so not ankylosing spondylitis) |
Hook:All three are required - 'FDS': Flowing bone, Discs intact, SI joints Spared.
Mnemonic
DISHDISH versus AS
| D | Diabetes DISH links to diabetes, obesity, metabolic syndrome; AS links to HLA-B27 |
| I | Inflammation absent DISH is non-inflammatory; AS is inflammatory spondyloarthritis |
| S | SI joints spared DISH spares the SI joints; AS fuses them - the single best discriminator |
| H | Hefty osteophytes DISH = bulky flowing 'candle-wax'; AS = thin vertical syndesmophytes |
| D | Diabetes DISH links to diabetes, obesity, metabolic syndrome; AS links to HLA-B27 | S | SI joints spared DISH spares the SI joints; AS fuses them - the single best discriminator |
| I | Inflammation absent DISH is non-inflammatory; AS is inflammatory spondyloarthritis | H | Hefty osteophytes DISH = bulky flowing 'candle-wax'; AS = thin vertical syndesmophytes |
Hook:Spell DISH to recall the four features that separate it from ankylosing spondylitis.
Mnemonic
RIGIDWhy the DISH Spine Is Dangerous
| R | Rigid lever Long fused segment acts as a single brittle lever arm |
| I | Invisible Fracture lines are easily missed on plain films over flowing bone |
| G | Ground-level fall Low-energy trauma is enough to fracture the ankylosed spine |
| I | Instability Three-column transverse fractures are grossly unstable |
| D | Deficit/Death High rates of spinal cord injury, epidural haematoma and mortality |
| R | Rigid lever Long fused segment acts as a single brittle lever arm | I | Instability Three-column transverse fractures are grossly unstable |
| I | Invisible Fracture lines are easily missed on plain films over flowing bone | D | Deficit/Death High rates of spinal cord injury, epidural haematoma and mortality |
| G | Ground-level fall Low-energy trauma is enough to fracture the ankylosed spine |
Hook:A RIGID spine fractures, hides the fracture, and then does badly - hence aggressive imaging and fixation.
Overview and Epidemiology
Definition DISH (Forestier's disease) is a systemic, non-inflammatory enthesopathy characterised by progressive calcification and ossification of ligaments and entheses, most prominently the anterior longitudinal ligament of the spine. It produces flowing, "candle-wax" new bone that bridges vertebrae and stiffens the spine.
Key concept
- It is a disease of abnormal new bone formation at entheses, not of inflammation or of the disc.
- Because the discs and facet/SI joints are spared, DISH is distinguished from both ankylosing spondylitis and degenerative spondylosis (according to PubMed, Mader et al., RMD Open 2020).
Epidemiology
- Common in older adults; prevalence rises steeply with age and varies widely by definition and population.
- Male predominance (roughly 2:1) and a peak in the 6th decade onward.
- Strong, reproducible associations with type 2 diabetes mellitus, obesity, higher BMI, hyperuricaemia and the metabolic syndrome (according to PubMed, Sarzi-Puttini & Atzeni, Curr Opin Rheumatol 2004; Brikman et al., Semin Arthritis Rheum 2023).
- Increasingly recognised in younger obese patients - in one bariatric cohort, 18% of obese patients aged 50 or under met Resnick criteria, far above the expected general-population rate (according to PubMed, Brikman et al., 2023).
Why it matters for the orthopaedic exam
- Most DISH is asymptomatic and incidental, but candidates are tested on three orthopaedic consequences: the ankylosed-spine fracture, mechanical dysphagia from cervical osteophytes, and the distinction from ankylosing spondylitis.
Pathophysiology and Anatomy
The enthesis and new bone formation
- The primary lesion is at the enthesis (the insertion of ligament/tendon into bone).
- New bone forms through both endochondral and membranous ossification pathways, driven by metabolic and growth-factor signalling rather than inflammation (according to PubMed, Sarzi-Puttini & Atzeni, Curr Opin Rheumatol 2004).
- Candidate metabolic mediators include insulin/IGF-1 (linking to diabetes and obesity) and matrix Gla protein.
The anterior longitudinal ligament (ALL)
- Runs along the front of the vertebral bodies.
- In DISH it ossifies into a thick anterolateral band that bridges across discs - giving the flowing "dripping candle wax" appearance.
- The disc itself is spared, which is why disc heights stay relatively normal.
The thoracic right-sided predominance
- DISH characteristically favours the right side of the thoracic spine (around T7-T11).
- The classic explanation is mechanical: the pulsatile descending thoracic aorta lies on the left and is thought to suppress ossification on that side, so new bone forms preferentially on the right.
The biomechanics of rigidity
- As segments bridge, the spine loses its normal shock-absorbing flexibility and behaves like a single long bone.
- Combined with age-related osteoporosis, this creates a long, brittle lever arm - the central reason ankylosed spines fracture from trivial force.
Classification Systems
Resnick & Niwayama Criteria (the reference standard)
DISH is diagnosed radiographically when all three are present:
- Flowing ossification along the anterolateral aspect of at least 4 contiguous vertebral bodies.
- Relative preservation of disc height at the involved levels (excludes degenerative spondylosis).
- Absence of apophyseal (facet) joint ankylosis and of sacroiliac erosion, sclerosis or fusion (excludes ankylosing spondylitis).
A systematic review confirmed that no consensus exists for diagnosing early DISH; over 20 partly overlapping criteria sets exist, but spinal hyperostosis is required by all (according to PubMed, Kuperus et al., Rheumatology 2017).
Clinical Assessment
Most patients are asymptomatic - DISH is frequently an incidental finding on chest or abdominal imaging.
When symptomatic, think in three buckets:
- Axial: thoracolumbar stiffness and a dull ache; reduced spinal range of motion; reduced chest expansion if extensive.
- Mechanical compression (cervical):
- Dysphagia from large anterior cervical osteophytes compressing the pharynx/oesophagus (Forestier dysphagia).
- Rarely stridor, hoarseness or difficult intubation from anterior cervical mass effect.
- Neurological: usually only when DISH coexists with OPLL (posterior ossification) producing canal stenosis and myelopathy, or after a fracture.
The acute presentation that must never be missed
- An older patient with a stiff spine who has new spinal pain after a seemingly trivial fall.
- Pain may be the only sign initially; deficits can appear or progress hours to days later.
New Pain in a Rigid Spine = Fracture Until Proven Otherwise
In a patient with known or suspected DISH (or ankylosing spondylitis), treat any new neck or back pain after even a minor fall as a fracture. Image the WHOLE spine with CT - non-contiguous and second fractures are common, and plain films routinely miss the injury.
Differential Diagnosis
Distinguishing DISH From Its Mimics
| Condition | Key Distinguishing Feature | Imaging Clue | Typical Pattern |
|---|---|---|---|
| DISH (Forestier) | Non-inflammatory enthesopathy; SI joints and discs spared | Flowing anterolateral ossification over 4+ levels, right thoracic predominance | Older, male, diabetic/obese, often asymptomatic |
| Ankylosing spondylitis | Inflammatory; fuses SI joints; HLA-B27 positive | Thin vertical syndesmophytes (bamboo spine), squared vertebrae, fused SI joints | Younger, inflammatory back pain, raised CRP |
| Degenerative spondylosis | Disc degeneration is primary | Reduced disc height, discrete horizontal osteophytes, vacuum phenomenon | Older, mechanical pain |
| OPLL | Ossification of the POSTERIOR longitudinal ligament | Ossified strip behind the vertebral bodies in the canal; frequently coexists with DISH | Myelopathy more than axial pain, East Asian predominance |
| Spondyloarthritis (psoriatic/reactive) | Inflammatory, asymmetric, peripheral enthesitis | Chunky asymmetric syndesmophytes, sacroiliitis | Skin/nail or post-infective history |
| Acromegaly | Growth-hormone driven bony overgrowth | Posterior vertebral scalloping, enlarged sella, widened disc spaces | Acral enlargement, soft-tissue changes |
Imaging and Investigations
Workup Protocol
Plain RadiographsFirst Line / Diagnosis
- Lateral spine films show the flowing anterolateral ossification - apply the Resnick criteria here.
- Look specifically for preserved disc heights and normal SI joints to separate from spondylosis and AS.
- In trauma, plain films are unreliable - the fracture is often hidden by overlying bone.
CTEssential in Trauma
- CT the entire spine for any suspected ankylosed-spine fracture; it best shows the bony fracture line and three-column involvement.
- Defines fracture morphology (commonly transverse/extension type) for surgical planning.
MRICord, Ligaments and Haematoma
- Add MRI when there is a neurological deficit, unexplained pain, or to exclude spinal epidural haematoma.
- In DISH trauma, spinal epidural haematoma is common and may itself require decompression (according to PubMed, Vierunen et al., Eur Radiol 2023).
- One large series found routine MRI changed management in only a minority, so reserve it for deficits or suspected disco-ligamentous/canal pathology rather than performing it reflexively in every case (according to PubMed, Tavolaro et al., Spine J 2019).
BloodsExclude Mimics / Comorbidity
- HLA-B27 and inflammatory markers help exclude ankylosing spondylitis (expected normal/negative in DISH).
- Screen for diabetes and metabolic syndrome given the strong association.
Management Algorithm
Decision pathway
- Incidental, asymptomatic DISH: reassure and address metabolic risk factors (diabetes, weight). No spinal intervention.
- Axial stiffness/pain: analgesia, physiotherapy, activity modification.
- Cervical dysphagia: ENT/swallow assessment; conservative first (diet, posture, anti-reflux); anterior osteophytectomy if refractory or causing airway compromise.
- Suspected fracture (any new pain after trauma): immobilise, CT whole spine, add MRI if deficit/haematoma suspected, then surgical stabilisation for unstable injuries.
- Coexisting OPLL with myelopathy: manage as a stenosis/myelopathy problem (decompression with or without fusion).
Non-Operative Management
For the common, stable, symptomatic patient:
- Education and reassurance - most DISH is benign and incidental.
- Analgesia (paracetamol, NSAIDs with caution given comorbidity) and physiotherapy for stiffness.
- Metabolic optimisation: weight loss, glycaemic control - the modifiable associations.
- Dysphagia: dietary modification, upright posture, anti-reflux measures and speech/swallow therapy before considering surgery.
Non-operative care of fractures is largely abandoned for unstable three-column injuries because of high rates of displacement, secondary neurology and mortality; it is reserved only for genuinely stable injuries or patients unfit for any surgery, and even then needs close monitoring.
Surgical Technique
Long-segment posterior instrumented fusion
- Goal: neutralise the long rigid lever arm and prevent displacement of an inherently unstable fracture.
- Construct: pedicle screws spanning at least 3 levels above and 3 below the fracture (long constructs resist the cantilever forces of a fused spine).
- Augmentation: PMMA cement augmentation of screws improves purchase in osteoporotic ankylosed bone; percutaneous placement limits blood loss and wound problems in frail patients (according to PubMed, Buxbaum et al., 2021).
- Positioning: transfer and position carefully in the pre-injury alignment; never force a kyphotic/hyperextended spine flat.
- Decompression: add if there is cord compression or an epidural haematoma.
Complications
Key Complications and How to Mitigate Them
| Complication | Why It Happens | Mitigation |
|---|---|---|
| Unstable spine fracture from low-energy trauma | Long rigid lever arm + osteoporosis behaves like a brittle long bone | High index of suspicion; CT whole spine for any new pain |
| Spinal cord injury / late deficit | Three-column instability, displacement, epidural haematoma | Early stabilisation; MRI if deficit; avoid forced repositioning |
| Spinal epidural haematoma | Bleeding into the canal after fracture in a rigid spine | MRI when deficit/unexplained pain; decompress if compressive (Vierunen 2023) |
| Missed / non-contiguous fracture | Fracture line hidden by flowing bone; second fractures common | Image the entire spine, not just the painful region |
| Dysphagia / aspiration / difficult intubation | Bulky anterior cervical osteophytes and airway distortion | Swallow assessment; anticipate difficult airway; osteophytectomy if refractory |
| Surgical morbidity in frail patients | Older, diabetic, often osteoporotic, multiple comorbidities | Cement-augmented and percutaneous fixation to cut blood loss (Buxbaum 2021) |
Postoperative Care
After fracture fixation:
- Mobilise as early as the construct and comorbidities allow; these elderly patients deteriorate quickly with immobility (pneumonia, VTE, delirium, pressure injury).
- VTE prophylaxis, careful glycaemic control, and aggressive medical co-management - postoperative medical complications occur in a large minority of ankylosed-spine fracture patients (according to PubMed, Buxbaum et al., 2021).
- Monitor neurology closely for delayed deficit (haematoma, displacement) in the first days.
After cervical osteophytectomy:
- Watch the airway and swallowing closely in the early postoperative period (oedema can transiently worsen dysphagia).
- Counsel that symptoms usually improve but the osteophyte can recur over time.
Outcomes and Prognosis
- Incidental DISH has an excellent prognosis - it is the associated metabolic disease (cardiovascular risk, diabetes) that drives long-term health, not the spinal ossification itself.
- Dysphagia from osteophytectomy generally improves, though recurrence is possible because the underlying disease continues.
- Ankylosed-spine fractures carry a sobering prognosis: high rates of spinal cord injury, neurological deterioration, medical complications and mortality, reflecting both the injury and the comorbid, elderly population.
- In post-traumatic DISH MRI series, spinal cord injury was present in the majority of those imaged, and spinal epidural haematoma was a frequent, potentially treatable contributor (according to PubMed, Vierunen et al., Eur Radiol 2023).
Controversies and Areas of Uncertainty
- No agreed criteria for early DISH - more than 20 criteria sets exist and disagree, hampering research and earlier diagnosis (according to PubMed, Kuperus et al., Rheumatology 2017).
- Routine MRI in every ankylosed-spine trauma? Evidence suggests MRI changes management in only a minority, supporting a selective (deficit/unexplained pain) rather than reflexive approach (according to PubMed, Tavolaro et al., Spine J 2019).
- Optimal construct length and the role of percutaneous/cement-augmented fixation continue to evolve, balancing biomechanical stability against the morbidity of open surgery in frail patients.
- Aetiology remains "idiopathic" - metabolic and genetic drivers are implicated but no specific disease-modifying drug exists (according to PubMed, Sarzi-Puttini & Atzeni, Curr Opin Rheumatol 2004).
Evidence Base
Diffuse Idiopathic Skeletal Hyperostosis of the Spine: Pathophysiology, Diagnosis, and Management
Le HV, Wick JB, Van BW, Klineberg EO • Journal of the American Academy of Orthopaedic Surgeons (JAAOS) (2021)
Key Findings:
- Defines DISH radiographically as flowing ossification along the anterior spine spanning at least 4 vertebral bodies.
- Emphasises strong associations with diabetes mellitus and metabolic derangements despite unknown aetiology.
- Highlights that spinal ankylosis predisposes to unstable fractures from low-energy trauma requiring careful management.
Clinical Implication: The single best orthopaedic overview: anchor the diagnosis on the 4-level flowing ossification rule and treat the ankylosed spine as fracture-prone.
Classification criteria for diffuse idiopathic skeletal hyperostosis: a lack of consensus
Kuperus JS, de Gendt EEA, Oner FC, et al. • Rheumatology (Oxford) (2017)
Key Findings:
- All 24 reviewed criteria sets require spinal hyperostosis for the diagnosis of DISH.
- Major disagreement persists over the threshold number of vertebrae and over defining early disease.
- More than half of criteria sets are dichotomous and ignore the progressive nature of DISH.
Clinical Implication: Quote the Resnick criteria as the reference standard, but know that diagnosing EARLY DISH is genuinely contentious.
Post-traumatic spinal hematoma in diffuse idiopathic skeletal hyperostosis (DISH)
Vierunen RM, Haapamaki VV, Koivikko MP, Bensch FV • European Radiology (2023)
Key Findings:
- Spinal epidural haematoma occurred in 49% and spinal cord injury in 61% of post-traumatic DISH patients.
- Ground-level fall (69%) was the commonest mechanism; a transverse AO type B fracture (39%) was the commonest injury.
- Spinal canal narrowing and cord impingement correlated with worse pre-treatment neurological (Frankel) grade.
Clinical Implication: Low-energy falls cause unstable fractures and frequent epidural haematoma - MRI is justified when there is deficit or unexplained pain to find treatable compression.
Is routine MRI of the spine necessary in trauma patients with ankylosing spinal disorders or is a CT scan sufficient?
Tavolaro C, Ghaffar S, Zhou H, et al. • The Spine Journal (2019)
Key Findings:
- MRI revealed an additional injury not seen on CT in only 6 of 124 patients (4.8%).
- Management changed after MRI in just 3.2% (4/124), mostly disco-ligamentous hyperextension injuries.
- Authors recommend selective MRI (neurological deficit or possible disco-ligamentous injury) rather than routine use.
Clinical Implication: CT is the workhorse for the ankylosed-spine fracture; reserve MRI for deficits or suspected canal/disco-ligamentous pathology.
Percutaneous, PMMA-augmented, pedicle screw instrumentation of thoracolumbar ankylotic spine fractures
Buxbaum RE, Shani A, Mulla H, Rod A, Rahamimov N • Journal of Orthopaedic Surgery and Research (2021)
Key Findings:
- Mean age 76 with a mean of 14 ankylosed levels; all had at least one comorbidity.
- Percutaneous cement-augmented fixation gave short operative times (mean 131 min) and low transfusion needs.
- All fractures united without loss of reduction; all retained pre-op ASIA grade and three improved.
Clinical Implication: In frail, osteoporotic DISH patients, percutaneous PMMA-augmented long-segment fixation achieves union with low blood loss - a practical surgical strategy.
High prevalence of diffuse idiopathic skeletal hyperostosis (DISH) among obese young patients
Brikman S, Lubani Y, Mader R, Bieber A • Seminars in Arthritis and Rheumatism (2023)
Key Findings:
- DISH was present in 18% of young obese patients, far above the expected ~5-10% for this age.
- DISH was associated with hypertension, smoking and obstructive sleep apnoea.
- Supports DISH as an obesity- and metabolic-syndrome-related musculoskeletal complication.
Clinical Implication: DISH is not just a disease of the very old - early-onset DISH should prompt evaluation for metabolic syndrome.
Viva Scenarios
Clinical Decision Scenarios
Use these scenarios to practise clinical reasoning and management decisions
CLINICAL SCENARIOStandard
DISH or Ankylosing Spondylitis?
CLINICAL PROMPT
"You are shown a lateral thoracolumbar radiograph of a 68-year-old man with a 'fused-looking' spine. How do you decide whether this is DISH or ankylosing spondylitis?"
PRACTICAL APPROACH
I would systematically apply the differences.
**In favour of DISH:**
- **Bulky, flowing 'candle-wax' anterolateral ossification** bridging 4 or more contiguous vertebrae.
- **Preserved disc heights** at involved levels.
- **Sacroiliac joints SPARED** (no erosion or fusion) - the single most useful discriminator.
- Older male, often diabetic/obese; non-inflammatory.
**In favour of ankylosing spondylitis:**
- **Thin vertical syndesmophytes** (bamboo spine), squared vertebrae.
- **Sacroiliac joints fused/eroded**.
- Younger patient, inflammatory back pain, HLA-B27 positive, raised inflammatory markers.
I would confirm by reviewing a dedicated **SI joint/pelvic view** and, if needed, check **HLA-B27 and CRP/ESR**, which I would expect to be negative/normal in DISH.
KEY CLINICAL POINTS
Apply Resnick: flowing ossification over 4+ levels, preserved discs, SPARED SI joints
SI joint status is the best single discriminator
DISH is non-inflammatory and HLA-B27 negative; AS is the opposite
Ossification morphology: bulky/flowing (DISH) vs thin syndesmophytes (AS)
COMMON PITFALLS
Calling any fused spine 'ankylosing spondylitis'
Forgetting to look at the SI joints
FURTHER QUESTIONS
"Both diseases share one dangerous orthopaedic complication - what is it?"
CLINICAL SCENARIOStandard
The Trivial Fall in a Rigid Spine
CLINICAL PROMPT
"A 78-year-old man with known DISH trips on a rug and complains of new mid-back pain. Neurology is intact. Plain films look 'unchanged'. What do you do?"
PRACTICAL APPROACH
I treat this as a **spinal fracture until proven otherwise**.
**Reasoning**: an ankylosed DISH spine behaves like a long bone with a long brittle lever arm; even low-energy trauma can cause a highly unstable, often transverse extension-type fracture. Plain films are **unreliable** - the fracture is hidden by flowing bone.
**Action:**
1. **Spinal precautions / immobilise in his pre-injury posture** (do NOT force him flat - this can cause cord injury).
2. **CT of the ENTIRE spine** (not just the painful area) - non-contiguous and second fractures are common.
3. **MRI** if any neurological deficit develops, pain is unexplained, or to exclude a spinal epidural haematoma (common in DISH trauma).
4. Treat an unstable injury with **long-segment posterior instrumented fusion**, ideally cement-augmented/percutaneous given his age and bone quality.
I would also admit and monitor neurology closely, because deficits can appear late from displacement or haematoma.
KEY CLINICAL POINTS
New pain after minor trauma in a rigid spine = fracture until proven otherwise
CT the WHOLE spine; plain films miss the injury
Immobilise in pre-injury alignment - never force flat
Watch for delayed deficit and epidural haematoma; default is surgical stabilisation
COMMON PITFALLS
Being reassured by 'normal' plain films
Sending the patient home or treating in a collar only
Forcing the spine into a neutral position
FURTHER QUESTIONS
"Why is non-operative bracing usually inappropriate for these fractures?"
CLINICAL SCENARIOStandard
Dysphagia With OPLL
CLINICAL PROMPT
"A 74-year-old man with DISH has dysphagia from large anterior cervical osteophytes. Conservative measures have failed and he wants surgery. The CT also shows multilevel OPLL with canal stenosis. How does that change your plan?"
PRACTICAL APPROACH
The coexisting OPLL fundamentally changes the risk.
**Problem**: simply excising the anterior osteophytes can **increase mobility at a previously stiff, stenotic segment**. In a spine where the cord is already compressed by OPLL, that new motion can precipitate **spinal cord injury**.
**Plan:**
- First **decompress and stabilise the cord risk**: posterior decompression and fusion at the mobile/stenotic levels is generally performed (often before) anterior osteophyte excision to protect the cord (as in reported cases).
- Then perform **anterior osteophytectomy** for the dysphagia via a standard anterior cervical approach, protecting the oesophagus, recurrent laryngeal nerve and great vessels.
- Anticipate a **difficult airway** and involve ENT/anaesthesia; counsel about **possible recurrence** of the osteophyte.
**Bottom line**: never treat the osteophyte in isolation when there is significant coexisting OPLL/instability - address the cord first.
KEY CLINICAL POINTS
Isolated osteophytectomy can destabilise a stenotic level and cause cord injury
Decompress/fuse the OPLL-related stenosis first to protect the cord
Plan for a difficult airway; protect oesophagus and RLN
Counsel about recurrence as the underlying disease persists
COMMON PITFALLS
Excising the osteophyte without recognising the OPLL stenosis
Underestimating the airway in a patient with a large anterior cervical mass
FURTHER QUESTIONS
"What conservative measures should be exhausted before offering cervical osteophytectomy?"
MCQ Practice Points
Diagnostic Criteria
Q: What are the Resnick criteria for DISH? A: All three of: flowing ossification over at least 4 contiguous vertebral bodies, relative preservation of disc height, and absence of SI joint and facet joint fusion/erosion.
DISH versus AS
Q: What single radiographic feature best separates DISH from ankylosing spondylitis? A: The sacroiliac joints. They are spared in DISH and fused/eroded in ankylosing spondylitis.
Thoracic Sidedness
Q: Why does thoracic DISH favour the right side? A: The pulsatile descending thoracic aorta on the left is thought to inhibit left-sided ossification, so new bone forms preferentially on the right (around T7-T11).
Associations
Q: Which metabolic conditions are strongly associated with DISH? A: Type 2 diabetes mellitus, obesity and the metabolic syndrome (also hyperuricaemia).
Trauma
Q: What is the most dangerous orthopaedic consequence of DISH and its classic mechanism? A: An unstable spinal fracture - typically a transverse, extension-type three-column injury from low-energy trauma (e.g. a ground-level fall), easily missed on plain films.
Guidelines, Registries & Global Practice
Global epidemiology
- DISH is common in older adults worldwide; prevalence rises with age and is reported across all populations, with figures varying widely because criteria differ (according to PubMed, Kuperus et al., Rheumatology 2017).
- Consistent male predominance (~2:1) and strong associations with type 2 diabetes, obesity, hypertension and the metabolic syndrome are seen internationally (according to PubMed, Sarzi-Puttini & Atzeni 2004; Brikman et al. 2023).
- Increasingly diagnosed in younger obese patients as CT use rises - 18% in one obese under-50 cohort (according to PubMed, Brikman et al., 2023).
Side-by-side guideline / consensus positions
| Body / source | Position on DISH |
|---|---|
| Resnick & Niwayama (reference radiographic criteria) | Diagnose on flowing ossification over 4+ contiguous vertebrae, preserved discs, and spared SI/facet joints - still the global standard. |
| International DISH consensus efforts (Kuperus et al.) | Acknowledge no agreed criteria for early DISH; call for criteria capturing the progressive phases of new bone formation. |
| AO Spine / ankylosed-spine trauma principles | Treat fractures of the ankylosed spine (DISH or AS) as unstable three-column injuries; CT the whole spine; favour long-segment instrumented stabilisation. |
| Orthopaedic review consensus (JAAOS, Le et al.) | Most DISH is managed non-operatively; surgery is reserved for fractures, refractory cervical dysphagia, and coexisting myelopathy. |
Registry / outcome evidence
- There is no dedicated DISH implant registry; the evidence base is retrospective cohorts and case series (e.g. MRI trauma cohorts, percutaneous fixation series).
- These consistently show frequent epidural haematoma and spinal cord injury after low-energy trauma and good union with cement-augmented, often percutaneous, long constructs in frail patients (according to PubMed, Vierunen 2023; Buxbaum 2021).
High- vs limited-resource practice variation
- High-resource settings: whole-spine CT (and selective MRI) for any ankylosed-spine trauma; percutaneous, cement-augmented long-segment fixation; multidisciplinary frailty co-management.
- Limited-resource settings: greater reliance on plain films (which miss these fractures) and open surgery; the universal priority everywhere is a low threshold to image the whole spine in a rigid spine with new pain.
Exam Day Cheat Sheet
DISH Summary
Clinical summary
Key Concepts
- •Non-inflammatory enthesopathy
- •Anterior longitudinal ligament ossification
- •Flowing 'candle-wax' bone
- •Linked to diabetes / obesity / metabolic syndrome
Resnick Criteria (all 3)
- •Flowing ossification over 4+ levels
- •Preserved disc heights
- •SI and facet joints spared
- •Right thoracic predominance (aorta)
DISH vs AS
- •SI joints SPARED (DISH) vs fused (AS)
- •HLA-B27 negative (DISH)
- •Bulky osteophytes vs thin syndesmophytes
- •Non-inflammatory vs inflammatory
Danger / Management
- •Unstable fracture from minor fall
- •CT whole spine - films miss it
- •Long-segment instrumented fusion
- •Anterior osteophytectomy for refractory dysphagia
Image Manifest
- dish-cervical-flowing-ossification.png: Lateral cervical radiograph, flowing anterior ALL ossification (PMC2981850, CC BY)
- dish-cervical-anterior-osteophyte.png: Lateral cervical radiograph, large anterior bridging osteophytes causing dysphagia (PMC2533017, CC BY)
- dish-thoracic-spondylophytes.png: Four-panel composite of DISH at cervical, thoracic and pelvic sites (PMC5376279, CC BY)