How should physiotherapists assess persistent low back pain
Persistent low back pain is one of the leading causes of disability worldwide and a frequent reason for physiotherapy referral. When symptoms last beyond six weeks or recur after an initial episode, a structured assessment becomes essential to rule out serious pathology, identify modifiable risk factors, and match treatment intensity to the person's risk of a poor outcome.
The goal of the initial assessment is not simply to confirm that back pain is present but to exclude specific causes, identify prognostic indicators that may delay recovery, and stratify the person into a treatment pathway that fits their risk profile. This guide outlines the assessment steps grounded in current clinical guidelines from NICE, the American Physical Therapy Association, and the WHO.
Step-by-Step Assessment Guide
1. Take a focused history
The assessment begins with a structured history covering the pain characteristics and associated features.
History elements to cover:
- Onset, type, site, and pattern of pain
- Any pain radiation into the leg
- Duration of symptoms and whether the pain is acute, subacute, or chronic
- Aggravating and relieving factors
- Previous episodes of back pain and how they resolved
- Associated symptoms such as morning stiffness, leg pain or weakness, muscle spasm, numbness or paraesthesia, weight loss
- Impact on daily functioning including work, study, relationships, and sleep
- Impact on psychological wellbeing, including fears about movement and expectations of recovery
NICE notes that non-specific lower back pain typically varies with posture and time and is exacerbated by movement. Pain severity does not necessarily correlate with functional impairment, so asking about function separately from pain intensity matters.
Action: Document all history elements. Use them to screen for red flags in the next step and to inform the risk stratification tool later.
2. Screen for red flags
Red flags are clinical indicators of potentially serious underlying pathology that require urgent medical referral rather than continued physiotherapy. They are uncommon but must be excluded at every encounter.
Red flags for cauda equina syndrome:
- Sudden-onset bilateral radicular leg pain or unilateral radicular pain progressing to bilateral pain
- Severe or progressive neurological deficit such as major motor weakness of knee extension, ankle eversion, or foot dorsiflexion
- Recent-onset difficulty initiating micturition or impaired sensation of urinary flow
- Urinary retention or overflow incontinence, faecal incontinence (late signs)
- Perianal or perineal sensory loss (saddle anaesthesia or paraesthesia)
- Unexpected laxity of the anal sphincter
Red flags for spinal fracture:
- Sudden onset of severe central spinal pain relieved by lying down
- Recent major trauma such as a road traffic collision or fall from a height
- Minor trauma or strenuous lifting in a person with osteoporosis
- Structural deformity of the spine or point tenderness over a vertebral body
Red flags for cancer:
- Age 50 years or over with gradual onset or progressive pain
- Severe unremitting lumbar pain, thoracic back pain, or night spinal pain preventing sleep
- Spinal pain aggravated by straining such as coughing, sneezing, or defaecation
- Unexplained weight loss
- Past history of cancer (breast, lung, prostate, renal, and gastric cancer more often metastasise to the spine)
- No symptomatic improvement after 4 to 6 weeks of conservative treatment
Red flags for infection:
- Fever or systemically unwell presentation
- Recent infection
- Diabetes mellitus, intravenous drug use, HIV infection, or immunosuppression
Action: If any red flag is present, stop the routine assessment pathway and refer immediately for medical evaluation and, where indicated, urgent imaging. NICE recommends that if serious underlying pathology is suspected, the clinician should refer to the relevant guidance on metastatic spinal cord compression, spondyloarthritis, or suspected cancer.
3. Perform a physical and neurological examination
When no red flag is identified, the physical examination aims to reproduce symptoms, assess range of motion, and screen for nerve root compression or other neurological deficits.
Examination components:
- Inspection of posture, spinal alignment, and gait
- Active range of motion of the lumbar spine
- Palpation for muscle spasm, trigger points, and localised tenderness
- Neurological examination of the lower limbs assessing strength, sensation, and tendon reflexes
- Straight leg raising test for nerve root tension
- Assessment for an extensor plantar response
Depending on clinical judgement, the assessor may also check anal sphincter tone and perianal sensation if cauda equina syndrome is a concern. The National Spine Network guidance states that a digital rectal examination is not required in primary care if cauda equina syndrome is already suspected, because it does not change management and should not delay referral.
Action: Record examination findings and correlate them with the history. Neurological deficits such as numbness, paraesthesia, motor weakness, or abnormal reflexes should prompt consideration of radiculopathy and, if persistent, eventual imaging or specialist referral.
4. Apply a risk stratification tool
When no specific underlying cause is suspected, NICE recommends using a risk stratification tool at the first point of contact with a healthcare professional for each new episode of low back pain, with or without sciatica.
The Keele STarT Back tool:
NICE specifically names the STarT Back risk assessment tool. It is a validated, simple prognostic questionnaire covering pain severity, function, expectations for recovery, and psychological distress. The resulting score stratifies the person into low, medium, or high risk for chronicity and disability.
Risk categories and matched pathways:
- Low risk: Likely to improve quickly. Offer simpler and less intensive support such as reassurance, advice to keep active, and guidance on self-management.
- Medium risk: Moderate risk of delayed recovery. Offer a structured exercise programme with or without manual therapy.
- High risk: Higher risk of a poor outcome. Offer more complex and intensive support, such as exercise programmes combined with a psychological approach, because psychosocial obstacles to recovery are common in this group.
Risk stratification tools are designed to identify people at increased risk of delayed recovery so that more intensive treatment can be offered in a timely manner to improve outcomes.
Action: Calculate the risk score at the first visit and use it to decide the initial treatment intensity. Reassess risk at each new episode, because risk profile can change between episodes.
5. Assess psychosocial obstacles to recovery
Persistent low back pain frequently involves modifiable psychosocial factors. The biopsychosocial perspective recommended by the WHO and NICE requires the physiotherapist to look beyond tissue pathology.
Psychosocial factors to assess:
- Fear avoidance beliefs about movement and activity
- Low expectations of recovery
- Catastrophising about pain
- Avoidance of normal activities based on inappropriate beliefs
- Mood disturbance, anxiety, or depressive symptoms
- Work-related stress and job dissatisfaction
NICE recommends combined physical and psychological programmes with a cognitive behavioural approach for people with persistent low back pain when psychosocial obstacles are significant or previous treatments have not been effective.
Action: Document psychosocial factors at the initial assessment. For people at high risk of poor outcome, build a treatment plan that addresses these obstacles, including referral to a combined physical and psychological programme if needed.
6. Decide on imaging
Routine imaging is not recommended for non-specific low back pain in a non-specialist setting. NICE explicitly advises against routinely offering imaging to people with low back pain with or without sciatica.
When imaging is appropriate:
- When a red flag suggests serious underlying pathology
- In specialist settings such as a musculoskeletal interface clinic or hospital, only when the result is likely to change management
- For radiculopathy that persists despite 4 to 6 weeks of conservative care including physiotherapy
- When symptoms progress or new neurological deficits develop during treatment
Imaging investigations correlate poorly with symptoms and often reveal incidental findings that do not explain the person's pain. Early imaging for uncomplicated pain can prolong recovery by focusing attention on non-clinically significant abnormalities.
Action: Withhold imaging in the absence of red flags. If imaging is later indicated, select the modality that answers the clinical question: X-ray for suspected fracture or alignment, MRI for soft tissue, disc, nerve root, infection, or tumour, and CT when MRI is contraindicated.
Conditions Mistaken for Persistent Non-specific Back Pain
A thorough assessment excludes other diagnoses that can present with persistent low back pain.
Specific causes to consider when reviewing the person:
- Spondyloarthritis including ankylosing spondylitis
- Vertebral compression fracture due to osteoporosis
- Spinal infection such as discitis or vertebral osteomyelitis
- Malignancy, including metastatic disease
- Cauda equina syndrome
- Hip pathology referred to the lower back
- Abdominal or pelvic organ referred pain
NICE recommends thinking about alternative diagnoses when examining or reviewing people with low back pain, particularly if they develop new or changed symptoms, and excluding specific causes such as cancer, infection, trauma, or inflammatory disease.
Red Flags, When to Stop and Refer
Contact the appropriate medical provider for urgent evaluation if you notice:
- Saddle anaesthesia or numbness in the groin or buttock area
- New urinary retention or faecal incontinence suggesting cauda equina syndrome
- Progressive motor weakness in the lower limbs over hours to days
- Severe central spinal pain relieved by lying down after trauma
- Fever with localised spinal pain suggesting infection
- History of cancer with new or progressive back pain
- Unexplained weight loss alongside back pain
- Night pain unrelieved by rest, concerning for tumour or infection
- Intravenous drug use or immunosuppression with new back pain
Common Questions
How is the STarT Back tool used and what does the score mean?
The STarT Back tool is a short questionnaire completed at the first point of contact for each new episode of low back pain. It produces a score that stratifies the person as low, medium, or high risk for chronicity and disability. Low risk supports reassurance and self-management advice. Medium risk supports a structured exercise programme with or without manual therapy. High risk supports more intensive combined physical and psychological care, because psychosocial obstacles to recovery are common in this group.
Why should I not request an MRI at the first visit?
NICE recommends against routinely offering imaging in a non-specialist setting for people with low back pain. Imaging investigations correlate poorly with symptoms and have low specificity. Many asymptomatic people show disc bulges and degenerative changes on MRI, and focusing on these findings can prolong recovery and lead to unnecessary interventions. Imaging should be reserved for when a red flag is present, when symptoms progress, or when conservative care has failed and the result is likely to change management.
How long should I try conservative care before reconsidering the diagnosis?
NICE defines chronic low back pain as lasting three months or more, and acute pain as lasting less than three months. If a person has had 4 to 6 weeks of appropriate conservative management including physiotherapy without improvement, reassess for red flags and consider whether radiculopathy or another specific cause has become more likely. Imaging in a specialist setting may then be appropriate if the result is likely to change management.
Can a physiotherapist assess psychosocial factors as well as physical ones?
Yes. The biopsychosocial perspective recommended by the WHO and NICE requires that all adults seeking care for persistent low back pain receive a thorough clinical assessment that includes psychosocial factors. The STarT Back tool explicitly screens for fear, catastrophising, and recovery expectations. When significant psychosocial obstacles are present, a combined physical and psychological programme using a cognitive behavioural approach is recommended.
What makes a person high risk for a poor outcome?
High risk is not defined by pain severity alone. The STarT Back tool identifies people based on pain intensity, functional limitation, low expectations of recovery, fear avoidance, catastrophising, and mood. People at high risk benefit from more complex and intensive support, including exercise programmes combined with a psychological approach, and from combined physical and psychological programmes when previous treatments have not been effective.
Protocol Summary
- Take a focused history covering pain pattern, radiation, duration, and impact on function
- Screen for red flags for cauda equina syndrome, fracture, cancer, and infection at every encounter
- Perform a physical and neurological examination of the lumbar spine and lower limbs
- Apply the Keele STarT Back tool to stratify risk and match treatment intensity
- Assess psychosocial obstacles including fear avoidance, catastrophising, and recovery expectations
- Withhold routine imaging in the absence of red flags
- Refer immediately for medical evaluation if any red flag is present
- Consider a combined physical and psychological programme for people at high risk of poor outcome
- Reassess risk at each new episode of low back pain
How Rovetia Helps
Rovetia helps physiotherapy practices document each step of a low back pain assessment by transforming dictation, clinical notes, and intake questionnaires into a structured, searchable patient timeline. Record red flag screening findings, neurological exam results, and STarT Back scores alongside prior episodes of back pain and treatment responses. The AI-powered chat against the full clinical history lets you quickly review what has been tried before and which interventions worked, so risk stratification and treatment planning stay grounded in the patient's complete record rather than a single visit.
Sources
- Assessment | Diagnosis | Back pain - low (without radiculopathy) | CKS | NICE
- Low back pain and sciatica in over 16s: assessment and management
- CPG | Interventions for the Management of Acute and Chronic Low Back Pain: Revision 2021 | APTA