Overview
Spondylolisthesis
1. Clinical Overview
Summary
Spondylolisthesis is the anterior (forward) displacement of one vertebra relative to the vertebra below. The most common levels affected are L5/S1 and L4/L5. The condition has several aetiologies, with the two most common being Isthmic Spondylolisthesis (Pars interarticularis defect – common in young athletes) and Degenerative Spondylolisthesis (Facet joint arthritis – common in older adults). Patients typically present with low back pain, often mechanical in nature, and may have radicular leg pain (From nerve root compression) or neurogenic claudication (Similar to spinal stenosis). Severity is graded by the Meyerding Classification (Grades I-V based on percentage slip). Most patients respond to conservative management (Physiotherapy, Analgesia, Activity modification). Surgical fusion is considered for high-grade slips, neurological deficits, or failure of conservative treatment. [1,2,3]
Clinical Pearls
"Pars Defect = Isthmic Type": Defect in the Pars Interarticularis (Spondylolysis) allows vertebra to slip forward. Common in gymnasts, Fast bowlers.
"L5/S1 is Most Common": Both Isthmic (L5 on S1) and Degenerative (L4 on L5 typical but L5/S1 common too).
"Step-Off Sign": Palpable step-off over the spinous processes on examination (In higher-grade slips).
"Scotty Dog Sign": On oblique lumbar X-ray – Pars defect looks like a collar on a Scotty dog's neck.
2. Epidemiology
Demographics
| Factor | Notes |
|---|---|
| Age - Isthmic | Adolescents, Young adults. Often discovered in athletic populations. |
| Age - Degenerative | Older adults (>50 years). Associated with spinal degeneration. |
| Sex | Isthmic: Male = Female. Degenerative: Female > Male (4:1). |
| Prevalence | ~5-7% of the general population have some degree of spondylolisthesis (Often asymptomatic). |
At-Risk Populations
| Group | Notes |
|---|---|
| Young Athletes | Gymnasts, Cricket fast bowlers, Weightlifters, Divers, Football linemen. Repetitive hyperextension stress on pars. |
| Older Adults | Degenerative facet joint changes. F>M. |
| Genetic Predisposition | Family history. |
3. Classification
Aetiological Classification (Wiltse Classification)
| Type | Cause | Notes |
|---|---|---|
| Type I: Dysplastic (Congenital) | Congenital abnormality of upper sacrum/L5 facets. | Present from birth. May progress during growth spurt. |
| Type II: Isthmic | Defect in Pars Interarticularis. | Most common type. Subtypes: IIa (Stress fracture/Lytic), IIb (Elongated pars), IIc (Acute fracture). |
| Type III: Degenerative | Facet joint arthritis and ligamentous laxity. | Most common in older adults. Usually L4/L5. |
| Type IV: Traumatic | Acute fracture of posterior elements (Not pars). | High-energy trauma. |
| Type V: Pathological | Destructive lesion (Tumour, Infection). | Bone destruction weakens vertebra. |
| Type VI: Iatrogenic | Post-surgical (After laminectomy/discectomy). | Destabilises spine. |
Meyerding Grading (Severity of Slip)
| Grade | Slip (%) | Description |
|---|---|---|
| I | 0-25% | Mild |
| II | 25-50% | Moderate |
| III | 50-75% | Severe |
| IV | 75-100% | Severe |
| V | >100% | Spondyloptosis (Complete displacement) |
4. Anatomy and Pathophysiology
Anatomy
- Pars Interarticularis: The bony segment of the vertebra connecting the superior and inferior articular processes. A "Stress riser" – vulnerable to fatigue fractures.
- Neural Foramen: Where nerve roots exit. Narrowed in spondylolisthesis.
- Spinal Canal: May be narrowed in high-grade slips → Stenosis.
Isthmic Spondylolisthesis (Type II)
- Repetitive Stress: Hyperextension and rotation (Athletes).
- Pars Stress Fracture (Spondylolysis): Fatigue fracture of pars. Bilateral defects allow slip.
- Vertebral Slippage: Upper vertebra slips forward on lower vertebra.
- Neural Compression: Foraminal narrowing → Radiculopathy.
Degenerative Spondylolisthesis (Type III)
- Facet Joint Arthritis: Degeneration and laxity of facet joints.
- Disc Degeneration: Loss of disc height.
- Segmental Instability: Allows forward slip.
- Spinal Stenosis: Slip + Degenerative changes = Central/Lateral stenosis → Neurogenic claudication.
5. Clinical Presentation
Symptoms
| Symptom | Notes |
|---|---|
| Low Back Pain | Most common. Mechanical (Worse with activity, Better with rest). |
| Radicular Leg Pain | Dermatomal distribution. Nerve root compression (Usually L5 or S1). |
| Neurogenic Claudication | Leg pain/Heaviness on walking, Relieved by sitting/Bending forward. (Degenerative type with stenosis). |
| Hamstring Tightness | Characteristic in children/Adolescents with high-grade slips. |
| Altered Gait | Wide-based, Waddling gait in high-grade slips. |
| Asymptomatic | Many incidental findings. |
Red Flags (Cauda Equina Syndrome)
| Feature | Significance |
|---|---|
| Urinary Retention / Incontinence | Bladder dysfunction. |
| Faecal Incontinence | Bowel dysfunction. |
| Saddle Anaesthesia | Numbness around perineum/buttocks. |
| Bilateral Leg Weakness | Motor deficit. |
| → EMERGENCY. Urgent MRI. Surgical decompression. |
Examination Findings
| Finding | Notes |
|---|---|
| Lumbar Lordosis | Often increased (Compensatory). |
| Palpable Step-Off | Gap or step between spinous processes (High-grade slips). |
| Hamstring Tightness | Limited straight leg raise (Not neurogenic = Not radicular). |
| Waddling Gait | High-grade slips in children. |
| Neurological Deficit | L5 or S1 radiculopathy (Weakness, Sensory loss, Reflex changes). |
6. Investigations
Imaging
| Modality | Findings |
|---|---|
| X-Ray Lumbar Spine (AP/Lateral) | Lateral view shows forward slip. Measure percentage slip. Oblique view shows Scotty Dog Sign (Pars defect = Collar on dog's neck). |
| CT Scan | Best for bony detail. Pars defect, Facet arthritis, Slip measurement. |
| MRI Lumbar Spine | Best for soft tissue. Disc degeneration, Neural compression, Stenosis. Use for surgical planning or if neurological symptoms. |
| SPECT Bone Scan | May show "Hot" pars in acute/healing stress fractures (Rarely used now). |
X-Ray Signs
| Sign | Description |
|---|---|
| Scotty Dog Sign | On oblique view – Vertebra resembles a Scotty dog. The pars is the dog's "neck." A defect appears as a "Collar" around the neck (Lucent line). |
| Napoleon's Hat Sign | On AP view in high-grade slips – L5 body appears like Napoleon's hat sitting on the sacrum. |
7. Management
Management Algorithm
SPONDYLOLISTHESIS DIAGNOSED
(Low back pain, +/- Radiculopathy, X-ray shows slip)
↓
ASSESS GRADE AND SYMPTOMS
- Meyerding Grade (I-V)
- Neurological examination
- Functional impact
↓
RED FLAGS (Cauda Equina)?
┌────────────────┴────────────────┐
YES NO
↓ ↓
**EMERGENCY MRI** GRADE I-II, STABLE, MINIMAL SYMPTOMS
Urgent Surgical Decompression ↓
CONSERVATIVE MANAGEMENT
Conservative Management (First-Line for Most)
| Intervention | Notes |
|---|---|
| Activity Modification | Avoid hyperextension activities. Limit high-impact sports initially. |
| Physiotherapy | Core stabilisation exercises. Strengthening of abdominals and paraspinals. Hamstring stretches. |
| Analgesia | Paracetamol, NSAIDs. Short courses. |
| Bracing | Controversial. May be used in acute pars stress fractures in young athletes (To allow healing). |
| Weight Loss | If obese. Reduces spinal load. |
| Epidural Steroid Injection | For radicular pain. Temporary relief. |
Surgical Management
| Indication | Procedure |
|---|---|
| Failure of Conservative Management (6+ months) | Consider surgery if persistent pain and disability. |
| Progressive Neurological Deficit | Decompression +/- Fusion. |
| Cauda Equina Syndrome | EMERGENCY Decompression. |
| High-Grade Slip (Grade III+) | Often requires stabilisation. Fusion. |
| Significant Instability | Fusion. |
Surgical Options
| Procedure | Notes |
|---|---|
| Posterolateral Fusion | Bone graft placed laterally to fuse vertebrae. +/- Pedicle screws. |
| Interbody Fusion (PLIF/TLIF/ALIF) | Disc removed. Cage with bone graft inserted. +/- Instrumentation. |
| Decompression (Laminectomy) | Relieves nerve compression. Often combined with fusion to prevent instability. |
| Pars Repair (Direct Repair) | Young patients with spondylolysis (Pars defect without significant slip). Buck's technique or similar. Not commonly done. |
8. Complications
| Complication | Notes |
|---|---|
| Slip Progression | Especially in high-grade slips during growth spurt. Monitor adolescents. |
| Neurological Deficit | Radiculopathy, Cauda Equina (Rare). |
| Chronic Pain | Even after treatment. |
| Surgical Complications | Non-union (Pseudarthrosis), Infection, Hardware failure, Adjacent segment disease. |
9. Prognosis and Outcomes
| Factor | Notes |
|---|---|
| Low-Grade Slips (I-II) | Generally good prognosis. Most managed conservatively. Rarely progress. |
| High-Grade Slips (III+) | Higher risk of progression and neurological compromise. May need surgery. |
| Adolescents | Risk of progression during growth spurt. Monitor with serial X-rays. |
| Degenerative Type | Usually stable. Responds to conservative management. Surgery for refractory symptoms or stenosis. |
10. Evidence and Guidelines
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| Low Back Pain | NICE NG59 | Physiotherapy-based, Non-surgical first. |
| Spondylolisthesis | NASS (North American Spine Society) | Grading, Conservative vs Surgical indications. |
Evidence Points
- Conservative vs Surgical: Most low-grade slips respond to conservative management. Surgery reserved for high-grade, progressive, or neurologically compromised patients.
- Fusion: Standard for unstable/high-grade slips. Solid fusion rates ~90% with modern techniques.
11. Patient and Layperson Explanation
What is Spondylolisthesis?
Spondylolisthesis means one of the bones in your spine (A vertebra) has slipped forward over the bone below it. This most often happens in the lower back.
Why does it happen?
- Young people/Athletes: Stress fractures in part of the vertebra (Pars) from repeated bending/twisting. Common in gymnasts and cricketers.
- Older adults: Wear and tear of the joints and discs in the spine allows slippage.
What are the symptoms?
- Lower back pain.
- Leg pain or numbness (If nerves are pinched).
- In severe cases (Rare), weakness or bladder/bowel problems (Seek help immediately).
How is it treated?
- Most cases: Physiotherapy (Strengthen your core muscles), Painkillers, Activity modification.
- Surgery: Only needed if pain is severe and persistent, or if there is nerve damage.
Will it get worse?
Low-grade slips rarely progress in adults. In teenagers, we monitor during growth spurts. Most people lead normal, active lives.
12. References
Primary Sources
- Meyerding HW. Spondylolisthesis. Surg Gynecol Obstet. 1932;54:371-377.
- Kalichman L, et al. Spondylolysis and spondylolisthesis: prevalence and association with low back pain. Spine. 2009;34(2):199-205. PMID: 19139672.
- Hu SS, et al. Spondylolisthesis and spondylolysis. J Bone Joint Surg Am. 2008;90(3):656-671. PMID: 18310716.
13. Examination Focus
Common Exam Questions
- Scotty Dog Sign: "What does the Scotty Dog Sign represent?"
- Answer: On oblique X-ray, the vertebra looks like a Scotty dog. A pars defect appears as a collar around the dog's neck.
- Most Common Level (Isthmic): "At what level does Isthmic Spondylolisthesis most commonly occur?"
- Answer: L5 on S1.
- Grading System: "What grading system is used for Spondylolisthesis?"
- Answer: Meyerding Classification (I-V based on percentage slip).
- Risk Population: "Which athletes are at increased risk of Isthmic Spondylolisthesis?"
- Answer: Gymnasts, Cricket fast bowlers, Weightlifters, Divers – Activities with repetitive lumbar hyperextension.
Viva Points
- Spondylolysis vs Spondylolisthesis: Spondylolysis = Pars defect WITHOUT slip. Spondylolisthesis = Pars defect WITH slip.
- Degenerative Type: Older females. L4/L5 most common. Associated with stenosis. Usually stable.
- Hamstring Tightness: Characteristic in children with high-grade slips. May cause waddling gait.
- Cauda Equina: Emergency. Urinary retention, Saddle anaesthesia, Bilateral weakness.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.