High-yield overview

Classification | Grading | Fusion Decisions

L5-S1Isthmic most common

L4-L5Degenerative most common

6%Population prevalence

MeyerdingKey grading system

WILTSE CLASSIFICATION

Type I Dysplastic

PatternCongenital facet abnormality

TreatmentOften progress, may need fusion

Type II Isthmic

PatternPars defect (spondylolysis)

TreatmentYoung, athletes, most common

Type III Degenerative

PatternFacet arthropathy

TreatmentOlder, L4-L5, intact pars

Type IV Traumatic

PatternAcute fracture

TreatmentRare, direct trauma

Critical Must-Knows

Isthmic = pars defect, young, L5-S1
Degenerative = facet arthropathy, older, L4-L5
Meyerding grades I-V based on slip percentage
High-grade (greater than 50%) usually needs reduction consideration
Fusion indicated for symptomatic with instability or progression

Clinical Pearls

"
Scotty dog sign on oblique X-ray = pars defect
"
Degenerative rarely exceeds Grade II
"
L5 radiculopathy common in isthmic L5-S1
"
Slip angle more important than grade for high-grade

Clinical Imaging

Imaging Gallery

A : Lateral radiograph of the cervical spine shows spondylolisthesis at C4-5; horizontal displacement between C4 and C5. B : The pedicle-facet (P-F) angle was defined by the intersection of a straight — A : Lateral radiograph of the cervical spine shows spondylolisthesis at C4-5; horizontal displacement between C4 and C5. B : The pedicle-facet (P-F) aCredit: Kim HC et al. via J Korean Neurosurg Soc via Open-i (NIH) (Open Access (CC BY))

Critical Exam Concepts

Wiltse Classification

Know the types. Dysplastic (I), Isthmic (II - most common), Degenerative (III), Traumatic (IV), Pathologic (V).

Meyerding Grades

Based on slip percentage. Grade I (less than 25%), II (25-50%), III (50-75%), IV (75-100%), V (spondyloptosis, greater than 100%).

High-Grade Management

Greater 50% controversial. Consider reduction to improve sagittal balance. Risk of L5 root stretch. In-situ fusion vs reduction.

Surgical Approach

Isthmic: often ALIF or circumferential. Degenerative: TLIF or posterolateral. Match technique to pathology.

Isthmic vs Degenerative Comparison

Feature	Isthmic (Type II)	Degenerative (Type III)
Age	Young (teens to 30s)	Older (greater 50)
Level	L5-S1 (90%)	L4-L5 (most common)
Pars	Defect (lysis)	Intact
Mechanism	Pars fracture	Facet arthropathy
Max slip	Can progress to high-grade	Rarely exceeds Grade II

Mnemonic

DITPPWiltse Classification

D	Dysplastic Type I - congenital facet abnormality
I	Isthmic Type II - pars defect (most common)
T	degenera-Tive Type III - facet arthropathy
P	traumatic (blunt) Type IV - acute fracture
P	Pathologic Type V - tumor, infection

D	Dysplastic Type I - congenital facet abnormality	P	traumatic (blunt) Type IV - acute fracture
I	Isthmic Type II - pars defect (most common)	P	Pathologic Type V - tumor, infection
T	degenera-Tive Type III - facet arthropathy

Hook:DITPP: the ways vertebrae slip!

Mnemonic

25-50-75-100Meyerding Grading

I	Grade I 0-25% slip
II	Grade II 25-50% slip
III	Grade III 50-75% slip (high-grade)
IV	Grade IV 75-100% slip (high-grade)
V	Grade V Greater than 100% (spondyloptosis)

I	Grade I 0-25% slip	IV	Grade IV 75-100% slip (high-grade)
II	Grade II 25-50% slip	V	Grade V Greater than 100% (spondyloptosis)
III	Grade III 50-75% slip (high-grade)

Hook:Divide the vertebra into quarters to grade the slip!

Mnemonic

PAINSSurgical Indications

P	Progressive slip Documented worsening
A	Associated neurological deficit Radiculopathy or claudication
I	Intractable pain Failed conservative trial
N	Nerve compression Cauda equina or significant root
S	Sagittal imbalance High-grade with severe deformity

P	Progressive slip Documented worsening	N	Nerve compression Cauda equina or significant root
A	Associated neurological deficit Radiculopathy or claudication	S	Sagittal imbalance High-grade with severe deformity
I	Intractable pain Failed conservative trial

Hook:When listhesis causes PAINS, consider surgery!

Overview and Epidemiology

Two Common Types

Isthmic and degenerative are most common. Isthmic = young, pars defect, L5-S1. Degenerative = older, intact pars, L4-L5. Know the differences for exams!

Isthmic Risk Factors

Extension sports (gymnastics, cricket fast bowling)
Adolescent growth spurt
Genetic predisposition
Male more than female
Repetitive hyperextension

Degenerative Risk Factors

Age greater than 50
Female more than male (3:1)
Facet orientation (sagittal)
Disc degeneration
Hormonal factors (postmenopausal)

Pathophysiology and Mechanisms

Pars Defect (Spondylolysis)

Location: Isthmus between superior and inferior articular processes.

Scotty dog sign: On oblique X-ray, pars defect appears as "collar" on the Scotty dog (neck = pars).

Mechanism: Fatigue fracture from repetitive hyperextension and rotation.

Bilateral defects: Allow vertebra to slip forward (listhesis).

Unilateral pars defect = spondylolysis without listhesis.

Scotty Dog Sign

On oblique lumbar X-ray: The Scotty dog represents the posterior elements. Eye = pedicle, nose = transverse process, ear = superior facet, front leg = inferior facet, neck = pars. A "collar" on the neck = pars defect.

Classification Systems

Wiltse-Newman Classification

Type	Name	Mechanism	Level
I	Dysplastic	Congenital facet abnormality	L5-S1
II	Isthmic	Pars defect (lytic, elongated, acute)	L5-S1
III	Degenerative	Facet arthropathy, intact pars	L4-L5
IV	Traumatic	Acute fracture other than pars	Any
V	Pathologic	Tumor, infection, bone disease	Any

Type II subtypes: IIa (lytic/fatigue fracture), IIb (elongated intact pars), IIc (acute pars fracture).

Clinical Assessment

History

Back pain: Worse with extension
Leg pain: Radicular pattern
Claudication: If associated stenosis
Activity: Sports history (isthmic)
Age of onset: Young = isthmic, old = degenerative

Examination

Posture: May see hyperlordosis or flexed stance
Step-off: Palpable in high-grade
Hamstrings: Tight (especially high-grade)
Gait: Waddling if severe (pelvic waddle gait)
Neuro: L5 and S1 root testing

Root Involvement by Level

Level	Exiting Root	Traversing Root	Clinical
L4-L5	L4	L5	L5 radiculopathy common (degenerative)
L5-S1	L5	S1	L5 radiculopathy (foraminal narrowing in isthmic)

High-Grade Signs

High-grade spondylolisthesis findings: Palpable step-off, flattened buttocks (vertical sacrum), tight hamstrings, waddling gait, trunk shortened. May have severe sagittal imbalance.

Differential Diagnosis

Mechanical and radicular back pain in this age range has a broad differential. The key discriminators are the presence of a slip on standing lateral radiograph, dynamic motion on flexion-extension, and the pattern of neural compression.

Distinguishing Spondylolisthesis from Mimics

Condition	Distinguishing Features	Key Investigation
Spondylolysis (no slip)	Pars defect without forward translation; extension-related pain	Oblique X-ray, CT, SPECT/MRI for activity
Degenerative spinal stenosis (no listhesis)	Neurogenic claudication, no vertebral translation	Standing lateral X-ray (no slip), MRI
Lumbar disc herniation	Acute dermatomal radiculopathy, positive SLR, no slip	MRI
Facet joint syndrome	Extension/rotation pain, no instability, no neural deficit	MRI/CT, diagnostic facet block
Pathologic / neoplastic listhesis	Night pain, weight loss, destructive lesion (Wiltse V)	MRI with contrast, CT, biopsy
Traumatic listhesis	Acute injury, fracture other than pars (Wiltse IV)	CT, MRI for ligamentous injury

Investigations

Plain Radiographs

Views:

AP, lateral (standing preferred)
Oblique (Scotty dog for pars)
Flexion-extension (dynamic instability)

Assess:

Meyerding grade (lateral view)
Slip angle
Pars defect (oblique)
Dynamic motion

Standing laterals better demonstrate true slip.

Slip Angle

Slip angle (angle between L5 and S1) is more important than grade for high-grade slips. High slip angle indicates worse sagittal imbalance and higher risk of progression.

Management Algorithm

Non-Operative Management

Acute pars stress reaction (young athlete):

Bracing (Boston overlap brace) 6-12 weeks
Activity modification
Physical therapy (flexion-based, core)
May heal if caught early (bone scan or MRI edema positive)

Chronic/established:

PT, core strengthening
Activity modification
Weight management
Monitor for progression

Many patients with low-grade slips remain asymptomatic.

Pars Repair Option

Direct pars repair (Buck fusion, Scott wiring, pedicle screw-hook construct) is an option in young patients with single-level isthmic spondylolysis, no significant disc degeneration, and no or minimal slip. Preserves motion.

Surgical Technique

Posterolateral Fusion with Instrumentation

Indications: Most low-grade listhesis.

Technique:

Prone positioning
Midline approach, exposure of transverse processes
Pedicle screw placement
Decompression if needed (laminectomy, foraminotomy)
Decortication and bone grafting to transverse processes

Key point: Adequate decompression of affected roots while achieving solid fusion.

L5 Root in High-Grade Reduction

L5 nerve root at significant risk with reduction of high-grade slips. The root is draped over the sacral dome and tethered. Aggressive reduction can stretch and injure it. Consider partial reduction and neuromonitoring.

Complications

Complication	Notes	Prevention/Management
Pseudarthrosis	5-15% depending on technique	Adequate graft, rigid fixation, smoking cessation
L5 root injury (high-grade)	With reduction	Partial reduction, neuromonitoring
Adjacent segment disease	Long-term	Consider minimizing fusion length
Progression (non-op)	Especially in young	Monitor, early fusion if progressing
Dural tear	5-10%	Careful technique, primary repair

Fusion Rate Factors

Fusion rates affected by: Number of levels, smoking, biology, technique, bone graft quality. Interbody fusion has higher rates than posterolateral alone.

Postoperative Care

Spondylolisthesis Fusion Recovery

Day 0-3Immediate

Pain control. DVT prophylaxis. Early mobilization. Brace if used. Neurological checks (especially after high-grade reduction).

Weeks 1-6Early

Activity restrictions (no BLT: bending, lifting, twisting). Wound care. Gradual walking increase. Brace compliance if prescribed.

Weeks 6-12Progressive

Radiographs to assess. Begin PT for core strengthening. Gradual activity increase. Wean brace.

Months 3-12Fusion

Fusion consolidation. Return to activities. Final radiographs for fusion assessment. CT if fusion in doubt.

Fusion Assessment

Solid fusion signs: No motion on flexion-extension, bridging bone, no lucencies around hardware. CT scan gold standard for fusion assessment.

Outcomes and Prognosis

Prognostic Factors

Better outcomes:

Low-grade slip
Predominant leg pain
Good bone quality
Non-smoker
Single level

Worse outcomes:

High-grade slip
Predominant back pain
Osteoporosis
Smoker
Multi-level disease

Controversies and Areas of Uncertainty

Decompression alone vs decompression + fusion

The defining modern debate. SLIP (Ghogawala, 2016) favoured adding fusion in grade I degenerative listhesis; the Swedish Spinal Stenosis Study (Forsth, 2016) found no benefit even in the listhesis subgroup. The reconciling view: fuse when there is demonstrable instability (dynamic motion, mobile slip, facet effusion), decompress alone when the segment is stable.

In-situ fusion vs reduction (high-grade)

Reduction improves sagittal/spinopelvic alignment but carries a real risk of L5 nerve root injury (highest during the final stage of reduction). No RCT settles this; many surgeons favour partial reduction with neuromonitoring over both full reduction and pure in-situ fusion.

Interbody vs posterolateral fusion

Interbody (TLIF/ALIF) raises radiographic fusion rates but the clinical advantage over posterolateral fusion is small and of debated significance, while adding cost and potential morbidity.

Healing and return-to-sport in spondylolysis

Optimal brace type, duration and timing of return to sport in adolescent athletes remain poorly standardised; the value of bracing over activity restriction alone is contested.

How to Handle Controversy in a Viva

Examiners reward candidates who acknowledge the conflicting trial evidence (SLIP vs Swedish study) and then give a principled, instability-based decision rather than a dogmatic "always fuse" or "never fuse" answer.

Evidence Base and Key Studies

The three NEJM randomised trials below are the most-quoted evidence in any spine viva: SPORT established that surgery beats non-operative care for symptomatic degenerative spondylolisthesis, while SLIP and the Swedish Spinal Stenosis Study reached opposite conclusions on whether to add fusion to decompression - the central modern controversy.

SPORT - Surgical vs Nonsurgical Treatment for Degenerative Spondylolisthesis

Weinstein JN, Lurie JD, Tosteson TD, et al • N Engl J Med (2007)

Key Findings:

Randomised plus observational cohorts, 607 patients, 13 US centres, degenerative listhesis with stenosis
Randomised arm had ~40% crossover in each direction, limiting intention-to-treat
As-treated analysis: surgery superior at 2 years - bodily pain effect 18.1, physical function 18.3, Oswestry -16.7
Treatment standardised as decompressive laminectomy with or without fusion

Clinical Implication: Decompressive surgery gives substantially greater pain and function gains than nonsurgical care for symptomatic degenerative spondylolisthesis with stenosis - the foundational indication for operating.

Limitation: High crossover forces reliance on as-treated analysis rather than intention-to-treat.

Verify on PubMed (PMID 17538085)

Exam Viva Scenarios

Use these scenarios to practise clinical reasoning and management decisions

CLINICAL SCENARIOStandard

Scenario 1: Young Athlete with Back Pain

CLINICAL PROMPT

"A 17-year-old fast bowler presents with back pain worse with extension and bowling. X-rays show bilateral pars defects at L5 with Grade I spondylolisthesis. How do you manage?"

PRACTICAL APPROACH

This is isthmic spondylolisthesis in a young athlete -a common presentation. The mechanism is repetitive hyperextension and rotation in fast bowling causing pars stress fractures (spondylolysis) progressing to bilateral defects and listhesis. For a Grade I slip in an adolescent, my initial management is conservative. I would obtain an MRI or bone scan (SPECT) to assess if there is active bone healing potential (edema/uptake suggests acute/subacute injury that may heal). If there is healing potential, I would trial bracing with a Boston overlap brace for 12 weeks, cessation of bowling, and physical therapy focusing on core strengthening and flexion-based exercises. Activity modification is essential -no cricket or extension activities during healing. If there is no healing potential (chronic defect on imaging), conservative treatment with PT remains appropriate as many patients with low-grade slips remain asymptomatic or minimally symptomatic. Surgery would be indicated for: failed conservative treatment with persistent pain, neurological symptoms (L5 radiculopathy), or documented progression on interval X-rays. Surgical options would include posterolateral fusion or TLIF at L5-S1, or in a motivated young athlete with single-level disease and no disc degeneration, I would consider direct pars repair to preserve motion.

KEY CLINICAL POINTS

Isthmic spondylolisthesis in athlete

Bracing if healing potential

Most low-grade managed conservatively

Surgery for failed conservative or progression

COMMON PITFALLS

Rushing to surgery for Grade I in adolescent

Missing healing potential assessment

Allowing return to sport too early

FURTHER QUESTIONS

"What is the Scotty dog sign?"

"When would you consider pars repair?"

"How would you monitor for progression?"

CLINICAL SCENARIOChallenging

Scenario 2: Degenerative Spondylolisthesis with Stenosis

CLINICAL PROMPT

"A 68-year-old woman has failed conservative treatment for neurogenic claudication. MRI shows L4-L5 stenosis and Grade I degenerative spondylolisthesis with 4mm dynamic instability. What is your surgical plan?"

PRACTICAL APPROACH

This is degenerative spondylolisthesis with stenosis and dynamic instability - a common scenario that was specifically studied in the SPORT trial. The combination of stenosis causing claudication, spondylolisthesis, and documented dynamic instability (4mm motion) indicates surgical management with decompression AND fusion. My surgical plan: Positioning prone on a radiolucent table (Wilson frame or Jackson). I would perform decompression at L4-L5 including laminectomy and bilateral lateral recess decompression to address the stenosis causing claudication. Given the listhesis and instability, decompression alone is insufficient and would likely lead to progression. I would add instrumented fusion. My preferred technique would be TLIF at L4-L5: pedicle screw instrumentation at L4 and L5, unilateral facetectomy (allows interbody access and decompresses that side), disc space preparation, cage insertion with bone graft, contralateral decompression and posterolateral fusion. This addresses both the stenosis (decompression) and instability (instrumented interbody fusion). The SPORT trial showed surgery is superior to conservative treatment for this presentation. Postoperatively, I would mobilize early with or without a brace depending on bone quality, and monitor fusion over 6-12 months.

KEY CLINICAL POINTS

Degenerative listhesis with stenosis = SPORT trial indication

Decompression PLUS fusion required

Dynamic instability confirms need for fusion

TLIF addresses both decompression and stability

COMMON PITFALLS

Decompression alone (would progress)

Missing the instability component

Over-extensive fusion

FURTHER QUESTIONS

"What did SPORT trial show?"

"TLIF vs posterolateral fusion?"

"What defines dynamic instability?"

CLINICAL SCENARIOCritical

Scenario 3: High-Grade Spondylolisthesis

CLINICAL PROMPT

"A 15-year-old girl presents with worsening back pain and hamstring tightness. X-rays show L5-S1 isthmic spondylolisthesis Grade III (55% slip) with high slip angle. What are the management considerations?"

PRACTICAL APPROACH

This is high-grade isthmic spondylolisthesis in an adolescent, which is a challenging scenario requiring careful consideration. The Grade III slip (55%) with high slip angle indicates significant deformity, and the progression of symptoms (worsening pain, tight hamstrings) is concerning for potential ongoing progression. In adolescents, high-grade slips can progress, especially during growth spurts. My management approach: First, complete workup including standing lateral X-ray (more accurate for slip measurement), MRI (assess neural compression, disc status), and assessment of sagittal balance. The tight hamstrings are a classic finding in high-grade slips due to pelvic retroversion compensating for the slip. Given the high grade, young age with growth remaining, and symptomatic presentation, this patient likely needs surgical intervention. The controversy in high-grade slips is whether to fuse in situ or attempt reduction. My approach would favor partial reduction for several reasons: young patient with good recovery potential, high slip angle contributing to sagittal imbalance that won't correct with in-situ fusion, and goal of improving overall spinopelvic alignment. However, I would counsel the family that the L5 nerve root is at significant risk with reduction. I would plan a circumferential fusion (anterior L5-S1 interbody fusion for height restoration followed by posterior instrumented fusion), use intraoperative neuromonitoring, and aim for partial rather than complete reduction to minimize neurological risk while improving sagittal parameters.

KEY CLINICAL POINTS

High-grade = greater 50% slip

High slip angle = worse sagittal imbalance

Adolescent with growth = progression risk

Reduction vs in-situ = balance benefit vs L5 risk

COMMON PITFALLS

Conservative management for high-grade adolescent

Aggressive full reduction risking L5

Not counseling about neurological risk

FURTHER QUESTIONS

"What is slip angle?"

"Why is L5 root at risk with reduction?"

"What is circumferential fusion?"

MCQ Practice Points

Wiltse Classification Question

Q: What is the most common type of spondylolisthesis? A: Type II (Isthmic) - pars defect from fatigue fracture. Most common level is L5-S1.

Level Difference Question

Q: What is the most common level for degenerative spondylolisthesis? A: L4-L5. Degenerative rarely exceeds Grade II. Isthmic is most common at L5-S1.

Meyerding Question

Q: What defines high-grade spondylolisthesis? A: Grade III or higher (greater than 50% slip). Grade III = 50-75%, Grade IV = 75-100%, Grade V = spondyloptosis.

Scotty Dog Question

Q: What does the collar on the Scotty dog sign represent? A: Pars interarticularis defect (spondylolysis). Seen on oblique lumbar X-ray.

High-Grade Risk Question

Q: What nerve root is most at risk during reduction of high-grade L5-S1 spondylolisthesis? A: L5 nerve root. Draped over sacral dome and tethered; stretched with reduction.

Guidelines, Registries & Global Practice

Global Epidemiology

Isthmic spondylolysis/spondylolisthesis: affects roughly 4-6% of the general adult population; the classic Fredrickson cohort found pars defects in about 4.4% of children by age 6 and 6% by adulthood, most at L5.
Marked ethnic variation: prevalence is far higher in some Inuit/Alaska Native populations (reported up to 30-50%) and lower in some Black African populations - evidence for a strong genetic and biomechanical contribution.
Sport exposure: rates rise sharply with repetitive lumbar hyperextension - cricket fast bowlers, gymnasts, divers, weightlifters and rowers.
Degenerative spondylolisthesis: predominantly over age 50, female-to-male around 3:1, classically L4-L5, associated with sagittally-oriented facets and disc degeneration.

Side-by-Side Guideline Positions

How Major Bodies Frame Surgical Decision-Making

Body / Source	Core Position	Emphasis
NASS (North America)	Decompression indicated for symptomatic stenosis with listhesis; fusion considered where instability present	Evidence-graded; supports surgery over medical/interventional care
NICE / BOA (UK)	Decompression for stenosis; fusion not routine and reserved for demonstrable instability or deformity	Conservative-first; cautious about adding fusion
AO Spine	Decision driven by instability, deformity and sagittal/spinopelvic parameters rather than slip grade alone	Classification- and alignment-led planning
EFORT / European consensus	Individualised; SLIP vs Swedish trial discordance means no universal fusion mandate	Shared decision-making, registry-informed

Registry & Practice Variation

Registry signal: large spine registries (e.g. Swespine, the UK British Spine Registry) consistently show good patient-reported gains after decompression for degenerative listhesis, with wide centre-to-centre variation in fusion rates that is not fully explained by case mix - underscoring practice-pattern (rather than evidence) driven fusion.
High-resource settings: ready access to MRI, intraoperative neuromonitoring, navigation/robotics and interbody implants; greater use of circumferential reconstruction for high-grade slips.
Limited-resource settings: reliance on plain radiographs and clinical assessment; in-situ posterolateral fusion (without expensive interbody cages or neuromonitoring) remains a safe, durable default, particularly for high-grade slips where reduction risk is highest.

Global Exam Focus

Across FRCS, FRACS, EBOT, ABOS and DNB exams the same core is tested: Wiltse and Meyerding classifications, isthmic vs degenerative differences, surgical indications (PAINS), the SLIP vs Swedish trial fusion controversy, and the L5 root risk in high-grade reduction.

SPONDYLOLISTHESIS

Clinical summary

Wiltse Classification (DITPP)

•I Dysplastic: congenital facet
•II Isthmic: pars defect (most common)
•III Degenerative: facet arthropathy
•IV Traumatic: acute fracture
•V Pathologic: tumor/infection

Meyerding Grades

•I: 0-25% (low-grade)
•II: 25-50% (low-grade)
•III: 50-75% (high-grade)
•IV: 75-100% (high-grade)
•V: greater 100% (spondyloptosis)

Isthmic vs Degenerative

•Isthmic: young, L5-S1, pars defect
•Degenerative: old, L4-L5, intact pars
•Degenerative rarely exceeds Grade II
•Isthmic can progress to high-grade

Surgical Indications (PAINS)

•Progressive slip
•Associated neurological deficit
•Intractable pain (failed conservative)
•Nerve compression
•Sagittal imbalance

High-Grade Considerations

•In-situ vs reduction controversy
•L5 root at risk with reduction
•Slip angle more important than grade
•Often needs circumferential fusion

Key Imaging Signs

•Scotty dog collar = pars defect
•Standing laterals best for grading
•Flexion-extension for instability
•MRI for neural compression assessment

Feature

Isthmic (Type II)

Degenerative (Type III)

Age

Young (teens to 30s)

Older (greater 50)

Level

L5-S1 (90%)

L4-L5 (most common)

Pars

Defect (lysis)

Intact

Mechanism

Pars fracture

Facet arthropathy

Max slip

Can progress to high-grade

Rarely exceeds Grade II

Type

Name

Mechanism

Level

Dysplastic

Congenital facet abnormality

L5-S1

Isthmic

Pars defect (lytic, elongated, acute)

L5-S1

III

Degenerative

Facet arthropathy, intact pars

L4-L5

Traumatic

Acute fracture other than pars

Any

Pathologic

Tumor, infection, bone disease

Any

Level

Exiting Root

Traversing Root

Clinical

L4-L5

L5 radiculopathy common (degenerative)

L5-S1

L5 radiculopathy (foraminal narrowing in isthmic)

Condition

Distinguishing Features

Key Investigation

Spondylolysis (no slip)

Pars defect without forward translation; extension-related pain

Oblique X-ray, CT, SPECT/MRI for activity

Degenerative spinal stenosis (no listhesis)

Neurogenic claudication, no vertebral translation

Standing lateral X-ray (no slip), MRI

Lumbar disc herniation

Acute dermatomal radiculopathy, positive SLR, no slip

MRI

Facet joint syndrome

Extension/rotation pain, no instability, no neural deficit

MRI/CT, diagnostic facet block

Pathologic / neoplastic listhesis

Night pain, weight loss, destructive lesion (Wiltse V)

MRI with contrast, CT, biopsy

Traumatic listhesis

Acute injury, fracture other than pars (Wiltse IV)

CT, MRI for ligamentous injury

Complication

Notes

Prevention/Management

Pseudarthrosis

5-15% depending on technique

Adequate graft, rigid fixation, smoking cessation

L5 root injury (high-grade)

With reduction

Partial reduction, neuromonitoring

Adjacent segment disease

Long-term

Consider minimizing fusion length

Progression (non-op)

Especially in young

Monitor, early fusion if progressing

Dural tear

5-10%

Careful technique, primary repair

SPORT - Surgical vs Nonsurgical Treatment for Degenerative Spondylolisthesis

Weinstein JN, Lurie JD, Tosteson TD, et al • N Engl J Med (2007)

Key Findings:

Randomised plus observational cohorts, 607 patients, 13 US centres, degenerative listhesis with stenosis
Randomised arm had ~40% crossover in each direction, limiting intention-to-treat
As-treated analysis: surgery superior at 2 years - bodily pain effect 18.1, physical function 18.3, Oswestry -16.7
Treatment standardised as decompressive laminectomy with or without fusion

Limitation: High crossover forces reliance on as-treated analysis rather than intention-to-treat.

Verify on PubMed (PMID 17538085)

Body / Source

Core Position

Emphasis

NASS (North America)

Decompression indicated for symptomatic stenosis with listhesis; fusion considered where instability present

Evidence-graded; supports surgery over medical/interventional care

NICE / BOA (UK)

Decompression for stenosis; fusion not routine and reserved for demonstrable instability or deformity

Conservative-first; cautious about adding fusion

AO Spine

Decision driven by instability, deformity and sagittal/spinopelvic parameters rather than slip grade alone

Classification- and alignment-led planning

EFORT / European consensus

Individualised; SLIP vs Swedish trial discordance means no universal fusion mandate

Shared decision-making, registry-informed

Grade	Slip %	Category
I	0-25%	Low-grade
II	25-50%	Low-grade
III	50-75%	High-grade
IV	75-100%	High-grade
V	Greater 100%	Spondyloptosis

Spondylolisthesis

Spondylolisthesis

WILTSE CLASSIFICATION

Critical Must-Knows

Clinical Pearls

Clinical Imaging

Imaging Gallery

Critical Exam Concepts

Wiltse Classification

Meyerding Grades

High-Grade Management

Surgical Approach

Isthmic vs Degenerative Comparison

DITPPWiltse Classification

25-50-75-100Meyerding Grading

PAINSSurgical Indications

Overview and Epidemiology

Isthmic Risk Factors

Degenerative Risk Factors

Pathophysiology and Mechanisms

Pars Defect (Spondylolysis)

How Vertebrae Slip

High-Grade Considerations

Scotty Dog Sign

Classification Systems

Wiltse-Newman Classification

Meyerding Slip Grading

High-Grade Classification

Clinical Assessment

History

Examination

Root Involvement by Level

High-Grade Signs

Differential Diagnosis

Distinguishing Spondylolisthesis from Mimics

Investigations

Plain Radiographs

CT Scan

MRI

Management Algorithm

Non-Operative Management

When to Operate (PAINS)

Surgical Options

Pars Repair Option

Surgical Technique

Posterolateral Fusion with Instrumentation

TLIF/PLIF/ALIF

High-Grade Management

L5 Root in High-Grade Reduction

Complications

Fusion Rate Factors

Postoperative Care

Spondylolisthesis Fusion Recovery

Outcomes and Prognosis

Prognostic Factors

Controversies and Areas of Uncertainty

Decompression alone vs decompression + fusion

In-situ fusion vs reduction (high-grade)

Interbody vs posterolateral fusion

Healing and return-to-sport in spondylolysis

Evidence Base and Key Studies

SPORT - Surgical vs Nonsurgical Treatment for Degenerative Spondylolisthesis

SLIP - Laminectomy plus Fusion vs Laminectomy Alone

Swedish Spinal Stenosis Study - Fusion Surgery for Lumbar Stenosis

PLF vs TLIF for Spondylolisthesis - Meta-analysis

ALIF vs PLIF/TLIF/PLF - Systematic Review

Surgical vs Conservative Treatment for Spondylolysis in Athletes

Exam Viva Scenarios

Scenario 1: Young Athlete with Back Pain

Scenario 2: Degenerative Spondylolisthesis with Stenosis

Scenario 3: High-Grade Spondylolisthesis

MCQ Practice Points

Guidelines, Registries & Global Practice

Global Epidemiology

Side-by-Side Guideline Positions

How Major Bodies Frame Surgical Decision-Making

Registry & Practice Variation

SPONDYLOLISTHESIS

Wiltse Classification (DITPP)

Meyerding Grades