Tests and Diagnosis
Physical Examination — What Your Doctor Is Checking
The Straight Leg Raise (SLR) Test
While you lie on your back, your doctor lifts your leg straight up. Pain radiating down the back of your thigh or calf suggests a disc herniation compressing a nerve.
However, there's an important caveat.
In people over 60, this test becomes significantly less reliable:
| Age Group | SLR Test Sensitivity (ability to detect disc herniation) |
|---|---|
| Younger adults | Approximately 91% |
| Over 60 | Approximately 33% |
This means that if you're over 60 and the SLR test is "negative" (no pain produced), it doesn't rule out a herniated disc (Qazi 2023). Your doctor knows this and will interpret the result alongside other findings.
Neurological Examination
When your doctor taps your knee or Achilles tendon with a reflex hammer, tests sensation in your feet, or checks the strength of your toes and ankles, they are identifying which nerve may be affected:
| Test | What It Reveals |
|---|---|
| Knee reflex | L3–L4 nerve root function |
| Achilles tendon reflex | S1 nerve root function |
| Ankle dorsiflexion strength | L4–L5 nerve root function |
| Big toe extension strength | L5 nerve root function |
| Foot sensation | Which nerve level is involved |
Other Important Tests
| Test | What It Assesses |
|---|---|
| FABER test | Sacroiliac joint (pelvic joint) problems |
| Instability testing | Spinal instability (excessive movement between vertebrae) |
| Single-leg stance test | Balance and stability (particularly important for functional assessment in older adults) |