Knowledge · Spondylolisthesis
Spondylolisthesis
In spondylolisthesis, one vertebra slips forward relative to the one below it. Many people have few or no symptoms; others develop load-dependent back pain or leg symptoms when nerves are compressed by the altered spinal mechanics. What matters is not the imaging finding alone, but the interplay of symptoms, clinical examination, and imaging.
What is spondylolisthesis?
The vertebral column consists of vertebrae connected by intervertebral discs and small facet joints. In spondylolisthesis, one vertebra slips relative to the one below — most commonly forward. The degree of displacement is graded according to Meyerding: grade I up to 25%, grade II 26–50%, grade III 51–75%, and grade IV 76–100%. Complete displacement with loss of endplate contact is called spondyloptosis and is rare. In clinical practice, low-grade forms are by far the most common.
Two forms account for the majority of cases:
- Degenerative spondylolisthesis: results from wear of the disc and facet joints, most commonly affects the L4/L5 segment, predominantly occurs in the second half of life, and is more frequent in women. The posterior arch is intact. Concurrent narrowing of the spinal canal or lateral recess — causing leg symptoms on walking and standing — is common.
- Isthmic spondylolisthesis: based on a defect of the pars interarticularis in the posterior arch (spondylolysis), usually the result of repetitive bony stress in adolescence — for example in sports involving frequent hyperextension. L5/S1 is most often affected. Because the posterior arch remains behind, central stenosis does not necessarily develop despite the slip. More typical is foraminal narrowing due to loss of disc height, frequently with compression of the L5 nerve root.
Less common are congenital forms, post-surgical slip, or slip in the context of other diseases. This distinction matters clinically: degenerative and isthmic forms differ in age of onset, location of nerve compression, and therefore in management.
Important for context: low-grade spondylolisthesis is a common finding and is not in itself a defect that needs to be "repaired". Treatment becomes relevant only when a matching clinical presentation is present.
Typical symptoms
The clinical presentation depends on whether and where nerves are compressed:
- Load-dependent back pain: deep-seated discomfort that worsens with prolonged standing, walking, or hyperextension, and eases in offloading positions
- Leg symptoms on walking and standing: pain, heaviness, tingling, or numbness in one or both legs — in degenerative slip usually reflecting concurrent spinal canal stenosis (neurogenic claudication)
- Radicular leg pain: with foraminal stenosis, often a sharp dermatomal pain — in isthmic L5/S1 slip typically along the L5 root to the dorsum of the foot, often present also when standing or extending
- Morning stiffness or start-up pain: may be present but are non-specific and do not confirm the slip as the cause
- In young athletes: load-dependent deep back pain without radiation after intensive training — an active spondylolysis must be considered
Symptoms and slip grade correlate only loosely: a grade II slip can be asymptomatic; a grade I slip with foraminal stenosis can be very painful.
Diagnosis: the patient comes before the image
Assessment begins with a thorough history and clinical examination: where exactly is the pain, in which posture, with which activity? Is there a dermatomal leg pain, neurological deficits, restricted walking distance? The hip, sacroiliac joints, circulation, and musculature are also assessed, as these can cause similar symptoms — and may co-exist with spondylolisthesis.
Depending on the situation, the following investigations follow:
- Weight-bearing radiographs: important baseline investigation for assessing slip grade, segment height, and spinal alignment. Under body load, the displacement may be more apparent than on lying MRI.
- MRI: standard investigation for visualising nerve compression — central, in the recess, or in the foramen — as well as discs and soft tissues
- CT: shows a bony pars defect and its stage with particular precision; used when this information is relevant for diagnosis, healing assessment, or surgical planning
- MRI with fluid-sensitive sequences: especially helpful in young athletes to detect an active stress reaction with bone oedema early and without radiation. SPECT/CT is only required for selected, unresolved diagnostic questions.
Comparing weight-bearing radiographs with lying MRI frequently provides sufficient information about segment behaviour under load. Flexion-extension radiographs are not part of my routine assessment and are used only for a specific, decision-relevant additional question. Their performance is poorly standardised; furthermore, no single measurement explains symptoms or justifies fusion on its own.
Treatment
Treatment is guided by form, symptoms, neurological findings, clinical course, and personal goals. Radiological slip alone does not justify surgery.
Non-operative treatment
For tolerable symptoms without significant neurological deficits, non-operative management is the first choice:
- Staying active: regular, graded movement is more beneficial than rest
- Targeted physiotherapy: strengthening of the deep trunk and hip muscles, posture and movement training; repeated end-range hyperextension is initially avoided
- Adapted aerobic activity: cycling, a stationary bike, or swimming, for example
- Weight reduction when overweight: can improve overall load tolerance and reduce mechanical demands on the spine
- Analgesia: time-limited, taking into account age, co-morbidities, and side effects
The natural history often permits a watchful waiting approach: low-grade slip remains largely stable over years in many adults. Degenerative slip can progress, but radiological progression and symptoms do not run reliably in parallel. Clinical development and function are therefore the key guides — not a single radiological measurement.
What is the role of infiltration?
A targeted infiltration — usually at the suspected nerve root — can, for a specific question, provide additional information: does the temporary response match the presumed pain source, and can a time-limited reduction in symptoms be achieved that facilitates activity and daily life? When several possible sources of compression exist, this can support clinical attribution. The diagnostic accuracy of such blocks is, however, only moderate; a positive or negative result must never in isolation determine whether to operate or which segment to treat. An infiltration removes neither the slip nor the stenosis and is not used as an uncritical series.
When should surgery be considered?
- Clinically attributable leg symptoms, restricted walking ability, or — with careful segmental attribution — back pain remain significantly burdensome despite adequate non-operative treatment,
- symptoms, examination, and imaging form a consistent, treatable picture,
- neurological deficits are present or progressive; or relevant progression is accompanied by worsening symptoms, neurological deficits, or deformity.
Possible cauda equina syndrome — with bladder or bowel dysfunction, saddle anaesthesia, or rapidly progressive weakness — is an emergency requiring immediate assessment.
Surgical techniques
Decompression alone — often sufficient
When central canal stenosis is the predominant finding in low-grade degenerative spondylolisthesis — presenting as neurogenic claudication or recessal leg symptoms — decompression alone is sufficient in many patients. The larger randomised long-term studies show that degenerative slip in itself is not a reason for routine additional fusion. What matters is decompression at the right level with maximum preservation of the stabilising structures, in particular the facet joints.
Foraminal stenosis: when stabilisation becomes worthwhile
A different situation arises when the nerve root is compressed in the foramen at the level of the slip — typically the L5 root in isthmic L5/S1 slip, but possible also in degenerative slip. Here, both the displacement and loss of disc height contribute to narrowing. Adequate direct decompression may also require extensive removal of the facet joint, further destabilising the segment.
In this configuration, fusion more often offers an independent benefit. A cage can restore segment height and indirectly widen the foramen; additional direct decompression may be necessary when there is significant bony stenosis. The extent of reduction is decided individually: complete anatomical reduction is not always necessary and can stress the L5 root particularly in higher-grade L5/S1 slip. The goal is not the perfect radiograph, but a reliably decompressed nerve root in a stable, well-aligned segment. In this case, stabilisation can be the smallest intervention that reliably addresses the problem.
When is fusion otherwise justified?
Further independent reasons may include symptomatic high-grade or progressive slip with significant deformity, degenerative scoliosis or sagittal malalignment, a revision situation, or anticipated iatrogenic destabilisation from the required decompression. Genuine mechanical instability convincing in the overall clinical and radiological picture may also play a role. The term lacks a uniform definition; I derive the decision from clinical findings, anatomy, and the anticipated additional benefit of fusion — not from a single measurement.
Where stabilisation is necessary, I perform it as tissue-preservingly as possible — in suitable anatomy via minimally invasive approaches and with precise screw placement under imaging guidance. Minimally invasive techniques can reduce blood loss and soft tissue damage, but are not a quality marker in themselves. Technique follows indication and anatomy — not the other way around.
What can realistically be expected?
How reliably surgery helps depends on the dominant clinical presentation and the chosen procedure. Decompression primarily improves leg symptoms and walking capacity; clearly attributable mechanical back pain can also improve after a justified stabilisation, but non-specific back pain remains less predictable. After stabilisation, many patients are mobile on the day of surgery or the following day; bony fusion takes several months. Possible complications include dural tear with cerebrospinal fluid leak, haematoma, infection, nerve injury, screw malposition, non-union, adjacent segment problems, and general anaesthetic and cardiovascular risks. Individual risk depends on the extent of surgery and overall health.
Young athletes with spondylolysis
In adolescents and young adults with new-onset load-dependent deep back pain after intensive training, an active stress reaction of the pars interarticularis should be considered. When recognised early, management is almost always conservative: temporary reduction of pain-provoking activity, followed by a structured programme of trunk strengthening, movement control, and gradual return to sport. An early lesion with bone oedema has a realistic chance of bony healing; even a chronic defect does not categorically exclude sport.
The long-term course of spondylolysis identified in childhood is frequently favourable. In the only population-based cohort followed for over 45 years, significant progression in adulthood was rare and health-related quality of life did not differ from the general population. Surgery is only exceptionally required in young athletes — for example, with persistent, clearly attributable symptoms despite structured treatment, neurological symptoms, or symptomatically progressive high-grade slip.
Pars repair: a motion-preserving option for selected young athletes
In young athletes, symptomatic spondylolysis can represent a particular management challenge. When load-dependent back pain persists despite thorough conservative treatment, direct repair of the pars interarticularis may be considered in carefully selected patients.
Prerequisites are a largely preserved intervertebral disc and intact facet joints at the affected segment, no significant vertebral slip, and the absence of another convincing pain source. History, clinical examination, MRI, and CT must together form a consistent picture. A targeted pars infiltration can in individual cases help assess its significance as a pain generator.
In pars repair, the bony defect is freshened, filled with bone graft, and directly stabilised. Unlike segmental fusion, the mobility of the affected spinal segment is preserved. This can be of particular relevance for young competitive and elite athletes.
Pars repair remains a targeted exception after conservative treatment has been exhausted. In the presence of advanced disc degeneration, significant vertebral slip, foraminal nerve compression, or another dominant pain source, it is generally not the appropriate solution.
My approach
My management pathway follows a clear sequence:
- History and clinical examination: I first establish which symptoms predominate, which form of slip is present, where nerves are compressed, and whether these findings are genuinely consistent.
- Integrating imaging purposefully: weight-bearing radiographs and lying MRI complement each other. Flexion-extension views play a role only for a rare, specific additional question.
- Targeted infiltration when it answers a specific question: it can support attribution to a nerve root and provide temporary relief — as one component of the overall picture, not as proof and not as a long-term treatment.
- Individual synthesis and counselling: I bring together findings, clinical course, and personal goals into a clear overall assessment — available in writing or as a second opinion on request.
- When surgery is performed: the smallest intervention with the greatest reliably achievable benefit. In central stenosis with low-grade degenerative slip, this is frequently decompression alone. In isthmic slip or clinically relevant foraminal stenosis, stabilisation can offer the decisive additional benefit. The extent of reduction and the surgical approach are chosen individually.
In older or medically complex patients, anaesthetic risk, operative duration, blood loss, and recovery time carry particular weight. The extent of surgery and anaesthetic technique are adapted to findings and the patient's condition — not the other way around.
What does the research say?
Radiological progression and symptoms do not run in parallel
In a cohort of 145 non-operatively managed patients with degenerative spondylolisthesis followed for at least ten years, displacement increased in 34%. Radiological progression did not, however, correlate with symptom development. This supports a clinically guided follow-up: not the imaging alone, but function, leg symptoms, and neurological findings determine the next steps.
Matsunaga S et al. J Neurosurg. 2000. PMID 11012048
Infiltration provides additional information, not proof
In a prospective controlled study, the diagnostic accuracy of selective lumbar nerve root blocks was only moderate. False-negative and false-positive responses occurred. A targeted infiltration can therefore support clinical attribution but must never in isolation determine the surgical segment.
Yeom JS et al. AJNR Am J Neuroradiol. 2008. PMID 18272560
Surgery can provide substantial benefit in symptomatic degenerative slip
In the large American SPORT trial, operated patients with degenerative spondylolisthesis and stenosis showed greater improvement in the as-treated comparison up to eight years than non-operatively managed patients. Due to extensive crossover between treatment groups, the randomised intention-to-treat analysis was less definitive. SPORT demonstrates the potential long-term benefit of surgery in carefully selected, symptomatic patients — not the necessity of operating on every case of spondylolisthesis.
Weinstein JN et al. N Engl J Med. 2007. PMID 17538085 · Abdu WA et al. Spine. 2018. PMID 29652786
Routine fusion offers no additional benefit in degenerative slip in most cases
The Swedish Spinal Stenosis Study found no advantage of additional fusion over decompression alone at two years — regardless of whether degenerative spondylolisthesis was present. At five years, no clinically relevant additional benefit was found either; re-operation rates did not differ. The study examined patients with one- or two-level central lumbar stenosis.
Försth P et al. N Engl J Med. 2016. PMID 27074066 · Karlsson T et al. Bone Joint J. 2024. PMID 38945544
The Norwegian NORDSTEN-DS trial specifically randomised patients with symptomatic stenosis and degenerative spondylolisthesis. At five years, 63% in both groups achieved an improvement in ODI of at least 30%; further operations were also similar after decompression alone and after fusion. Significant foraminal stenosis was, however, excluded.
Austevoll IM et al. N Engl J Med. 2021. doi:10.1056/NEJMoa2100990 · Kgomotso EL et al. BMJ. 2024. PMID 39111800
The smaller American SLIP trial found, in 66 selected patients with stable grade I slip, an advantage of fusion in the general physical SF-36 score and fewer re-operations, but no statistically significant difference in the spine-specific ODI. It represents an important counterpoint. Taken together, the larger and more recent long-term studies do not support routine fusion in low-grade degenerative slip with central stenosis.
Ghogawala Z et al. N Engl J Med. 2016. PMID 27074067
Important context: these studies address primarily central stenosis in low-grade degenerative slip. Their results cannot be uncritically applied to isthmic spondylolisthesis or significant foraminal stenosis at the slip level, where fusion can offer an independent benefit — though this does not automatically mean complete reduction is required.
Isthmic slip: fusion often worthwhile, reduction individualised
A randomised trial of 84 patients with low-grade isthmic spondylolisthesis and radiculopathy or claudication compared decompression alone with decompression and instrumented fusion. At two years, function, back pain, and perceived recovery were more favourable after fusion; re-operations were markedly less frequent (13% versus 47%). This evidence clearly distinguishes isthmic from typical degenerative spondylolisthesis.
Azizpour K et al. J Neurosurg Spine. 2021. PMID 34416736
Ekman and colleagues compared posterolateral fusion with a one-year exercise programme in 111 adults with symptoms lasting at least one year. After a mean of nine years, pain, functional scores, and quality of life did not differ significantly between groups; however, global self-assessment was more often positive after fusion (76% versus 50%). The short-term advantage had partly attenuated, but a moderate long-term benefit remained in the overall assessment.
Ekman P et al. Spine J. 2005. PMID 15653083
The natural history of spondylolysis is usually benign
In a study begun in 1955, 500 first-grade school children were examined; a pars lesion was identified in 30 and followed for 45 years. No participant with a unilateral defect developed a slip. In those with existing slip, progression slowed with each decade; no slip reached 40%, and SF-36 scores did not differ from the age-matched general population. This small cohort, not selected for pain, supports a cautious baseline approach but cannot make predictions for every symptomatic individual case.
Beutler WJ et al. Spine. 2003. PMID 12768144
Questions about your situation?
Tell me about your symptoms and send any existing reports. After history-taking, clinical examination, and review of your findings, I will summarise your situation in plain language. Together we will discuss whether a targeted infiltration, conservative management, or surgery is appropriate. If an operation is needed, I recommend the smallest intervention with the greatest reliably achievable benefit — including in the context of a second opinion.
Written and medically reviewed by Sebastian Bigdon, MD · Last updated: 26 August 2026 · The sources used are cited with PubMed references in the section «What does the research say?».
Frequently Asked Questions
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I take the time to review your imaging and provide a clear, written assessment – including as a second opinion.