7.1 Lumbar Spine Assessment
Key Takeaways
- Cauda equina red flags—saddle anesthesia, bowel/bladder change (especially urinary retention), and progressive motor deficit—stop special testing and refer emergently; infection, fracture, and cancer are the other imaging-first lumbar flags.
- Ipsilateral SLR is a sensitive, low-specificity disc screen (van der Windt 2010 Cochrane: about 91% sensitive, 26% specific versus surgery); Well (crossed) SLR is the more specific companion, and femoral-nerve stretch targets L2–L4.
- Laslett SI provocation is a cluster: 3 of 5 (distraction, compression, thigh thrust, sacral thrust, Gaenslen) or the later 2-of-4 rule that drops Gaenslen—not a single FABER.
- Lumbar stenosis is extension- and standing-worse with shopping-cart (flexion) relief; disc/radicular pain is more often flexion- and sitting-worse, and a negative SLR does not exclude stenosis.
- The stork/one-leg hyperextension test is not diagnostic gold for spondylolysis (Masci 2006); gymnasts and football linemen with extension pain still need imaging and referral.
Practice Analysis, 8th Edition (PA8) Domain II, task 0202, applied to the lumbar spine means you decide whether this back is safe to special-test, then you name the pain mechanism—mechanical, radicular, or referred—before you hang a diagnosis on one maneuver.
Red Flags First: Do Not Special-Test Through These
Cauda equina syndrome (CES) is a surgical clock. The cauda equina is the lumbar and sacral root bundle below the cord. Compression from a massive disc, fracture fragment, tumor, or epidural abscess/hematoma threatens bowel, bladder, sexual function, and saddle sensation.
Ask every lumbar athlete, out loud:
- Saddle anesthesia or hypoesthesia (perineum, inner thighs, buttocks—the skin that would touch a saddle)
- Bowel or bladder change, especially urinary retention (the most common CES feature), incontinence, or loss of filling awareness
- Progressive motor deficit, new bilateral weakness, a foot drop that is worsening, or gait collapse
Any of those stops the exam. Do not perform repeated extension, slump, or quadrant testing to 'confirm a disc,' and refer emergently for MRI. Incomplete CES still counts; waiting for a textbook saddle-plus-incontinence picture is the error.
The other imaging-first lumbar flags:
- Infection: fever, IV drug use, immunosuppression, recent spinal procedure, night pain, rapid worsening. Discitis, osteomyelitis, and epidural abscess are not 'mechanical LBP.'
- Fracture: high-energy trauma, axial load, or osteoporosis/insufficiency risk with sudden pain. A retropulsed fragment can itself cause CES.
- Cancer: prior malignancy, unexplained weight loss, night pain unrelieved by position. New back pain in known cancer is metastasis until work-up says otherwise.
If a red flag is present, your job is safety and referral, not a prettier special-test battery.
Mechanical versus Radicular versus Referred
Mechanical lumbar pain is loading-sensitive, usually axial or buttock, worse in some directions and better in others, without a hard neurologic deficit. Facet and posterior-element pain is often extension- and quadrant-worse. Discogenic pain is often flexion-, sit-, and sit-to-stand-worse. Neither pattern is an MRI report.
Radicular pain follows a root. True radiculopathy adds a myotomal, dermatomal, or reflex change—not just 'it shoots a little.' L4 is quadriceps and the patellar reflex; L5 is great-toe and ankle dorsiflexion and the dorsal foot; S1 is plantarflexion and the Achilles. Buttock-and-thigh pain that never goes below the knee is often referred, not sciatica.
Referred pain from the hip (groin, anterior thigh) and sacroiliac (SI) joint (sacral sulcus, buttock, sometimes posterior thigh) mimics lumbar disease. Hip internal-rotation loss, a painful log roll, or an SI cluster will save you from treating a hip as an L5 disc.
Neurodynamic and Segmental Tests
A positive neurodynamic test reproduces the athlete's familiar radicular symptoms, preferably with structural differentiation (ankle dorsiflexion or neck flexion that ramps the same leg pain). Isolated hamstring stretch is not a positive SLR.
| Test | Structure / construct | Positive finding | What +/− actually means |
|---|---|---|---|
| Straight-leg raise (SLR / Lasègue) | Sciatic tract, typically L4–S1 | Reproduction of posterior-leg/radicular pain, classically ~30–70° | Sensitive screen, poor specificity. van der Windt 2010 Cochrane review: about 91% sensitive and 26% specific for lumbar disc herniation versus surgery. Isolated low-back pain without leg symptoms is a negative SLR. |
| Well (crossed) SLR | Large or more medial disc affecting the contralateral root | Raising the well leg reproduces symptoms in the symptomatic leg | Lower sensitivity, higher specificity. A positive Well SLR is a stronger disc-herniation argument than ipsilateral SLR alone. |
| Slump | Neural mechanosensitivity of lumbar roots/sciatic tract in sitting | Familiar radicular pain that eases when neck flexion is released | Useful when supine SLR is equivocal. Still not a surgical indication by itself. |
| Femoral-nerve stretch | Femoral nerve / L2–L4 | Prone knee flexion ± hip extension reproduces anterior-thigh radicular pain | Upper lumbar or far-lateral disc territory. Do not confuse with rectus-femoris tightness (Ely) that is only a stretch sensation. |
| Quadrant (Kemp) | Ipsilateral posterior elements / foramen | Combined extension, sidebend, and rotation reproduces local lumbar or radicular pain | Local pain suggests facet/posterior elements; leg pain suggests foraminal loading. Do not crank this on a red-flag spine. |
| Central PA spring | Segmental pain/mobility | Pain or abnormal stiffness under a spinous-process PA | Localizes a segment. It does not diagnose instability, disc herniation, or a 'stuck facet.' |
Stenosis versus Disc, and the SI Cluster
Lumbar spinal stenosis (central or foraminal; often older or degenerative athletes) typically worsens with extension and standing and eases with flexion. The shopping-cart sign—relief leaning forward on a cart—is the clinical picture of neurogenic claudication. Downhill walking (more extension) is worse than uphill. SLR is often negative because this is not an acute tensioned disc. Do not force McKenzie extension into a stenotic, claudicating spine as if it were a young herniation.
A young athlete with flexion- and sitting-worse pain, a positive SLR/slump, and a myotomal deficit is the disc/radicular pattern. Repeated extension may centralize some of those patients—but not if motor is progressing or cauda flags appear.
Laslett SI cluster
SI pain is a provocation cluster, not a single FABER. Laslett and colleagues used distraction, thigh thrust, compression, sacral thrust, and Gaenslen. A common teaching rule is 3 of 5 positive tests reproducing familiar SI-region pain; the later algorithm uses 2 of 4 (dropping Gaenslen: distraction, thigh thrust, compression, sacral thrust) and stops when two are positive. Laslett 2005 is the source for treating this as a composite, not as one fancy test.
| Test | Structure / construct | Positive finding |
|---|---|---|
| Distraction (gapping) | Anterior SI ligaments | Familiar SI/buttock pain with posterior-lateral ASIS pressure (supine) |
| Compression | SI joint compression (side-lying) | Familiar SI pain with downward pressure on the iliac crest |
| Thigh thrust (posterior shear) | SI shear through the femur | Familiar SI pain with a posterior femoral thrust, hip flexed ~90°, sacrum blocked |
| Sacral thrust | SI via anterior sacral PA (prone) | Familiar SI pain with thrusts over the sacrum |
| Gaenslen | SI shear (one hip flexed, opposite extended off the table) | Familiar SI pain on the tested side |
One positive Gaenslen plus a noisy FABER is not an SI diagnosis. Pain must be the athlete's usual SI-region pain, and lumbar centralization (McKenzie) should have been considered so you are not labeling a disc as SI.
Spondylolysis, Listhesis, Core, and True Instability
Spondylolysis is a pars interarticularis stress injury, classically L5, in gymnasts, dancers, and football linemen (repetitive extension-rotation). Spondylolisthesis is the anterior slip once the pars fails bilaterally (Meyerding grades on a standing lateral radiograph).
The stork / one-leg hyperextension test (stand on one leg, extend the lumbar spine) is taught as a pars test. It is not diagnostic gold. Masci and colleagues (2006) found one-legged hyperextension not useful to detect or exclude active spondylolysis. Sensitivity and specificity are too poor to rule in or out. Extension-tender young athletes still need imaging and referral, not a 'negative stork, return to vault.'
Core versus true instability
Athletes are told they have 'instability' when they mean poor motor control. True radiographic instability is measurable translation or a progressive slip. A painful PA that lessens when the athlete lifts the legs (prone instability test) is a motor-control finding—worth a motor-control/core intervention—not a surgical listhesis. Do not brace every sore gymnast as a grade-III slip, and do not send a high-grade, symptomatic slip to aggressive extension loading.
Worked Scenario: Lineman versus Gymnast
A football lineman has acute lumbar and posterior-leg pain after a missed clean. SLR at 40° reproduces calf pain; the uninvolved-leg Well SLR also reproduces the calf pain. Great-toe extension is 4/5 and weaker than 20 minutes ago. No saddle change yet. Coach wants prone press-ups 'to put the disc in.'
Interpretation: this is an evolving radiculopathy with a more specific (Well SLR) disc-tension cluster and progressive motor loss. That is a referral now, not McKenzie. Aggressive extension loading on an acute disc with progressive neuro is the exam trap—centralization protocols assume a neurologically stable patient.
Contrast a 17-year-old gymnast with weeks of extension-related LBP, no leg pain, no red flags, and a positive stork. You still do not clear her on stork. Hold extension skills, refer for imaging (standing laterals look for listhesis; MRI or bone work-up for an active pars), and treat as a pars-stress until imaging speaks. A negative stork would not have cleared her either.
Exam trap: aggressive extension on an acute, neurologically worsening disc, or using stork as gold-standard clearance for a gymnast's pars.
A collegiate powerlifter reports acute lumbar and posterior-leg pain after a missed deadlift. Straight-leg raise reproduces posterior-leg pain at 40°, and ankle dorsiflexion is weaker than it was 30 minutes ago. There is no saddle anesthesia yet. The coach asks for McKenzie extension to 'put the disc back.' What is the correct athletic-training decision?
Which finding cluster should stop lumbar special testing and trigger emergency referral for suspected cauda equina rather than continued on-field evaluation?
A 61-year-old walker describes bilateral calf heaviness that worsens with downhill walking and eases when leaning on a shopping cart. Sitting is comfortable. Straight-leg raise is negative. How should this be interpreted?