Straight leg raise test
The examiner lifts the straightened leg while the patient lies supine; reproduction of radiating leg pain at a limited angle suggests nerve root irritation, often from a disc herniation.
Evaluation of the low back typically starts with a history exploring onset, aggravating movements, and any leg symptoms, followed by observation of posture, gait, and active range of motion.
Special tests help distinguish nerve-related pain from purely muscular pain, while a structured red-flag screen identifies the small number of cases needing urgent referral rather than a graded exercise program.
Assessment tests
Slump test
A seated sequence of trunk flexion, neck flexion, and knee extension that stretches the nerve pathway, used to help confirm a nerve-related source of leg symptoms.
Active range-of-motion screen
Flexion, extension, and side-bending are observed for range, quality, and whether specific directions reproduce pain, informing which exercise directions may help.
Prone instability test
Pain present while lying prone with legs off the table that eases when the trunk muscles are actively engaged suggests a stability-related component to the pain.
Neurological screen
Testing reflexes, strength, and sensation in the legs helps localize which nerve root, if any, is affected and gauges the severity of any nerve involvement.
Red flags
These warrant prompt clinical review rather than unsupervised exercise progression.
Saddle numbness or bladder changes
Numbness in the groin or inner thighs alongside new bladder or bowel difficulty can indicate cauda equina syndrome, a surgical emergency.
Progressive leg weakness
Worsening motor weakness in the leg, rather than pain alone, suggests significant nerve compression and warrants prompt evaluation.
History of cancer, fever, or unexplained weight loss
These features raise concern for infection or malignancy affecting the spine and typically prompt further medical work-up.
Significant trauma or osteoporosis with new pain
A fall or known bone-fragility condition combined with new severe back pain raises concern for vertebral fracture.
This staged approach — history, movement assessment, special tests, and red-flag screening — allows clinicians to direct the vast majority of patients toward active rehabilitation while identifying the few who need urgent or specialist care.
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