□ The posterior tibial nerve is now stretched like a bowstring across the popliteal fossa. □ Gently extend the knee until the pain is reproduced once again (Lasegite's sign) (Fig. □ Perform straight leg raising and at the limit flex the knee, reducing tension on the sciatic roots and hamstrings (Fig. □ When this limit is reached, gently dorsitlex the ankle, thereby applying further tension to the nerve root (Bragaardtest) (Fig. □ Repeat this on the affected side, asking the patient to report as soon as it becomes painful and where the pain or paresthesia is felt (Fig. □ With the knee extended, raise the leg on the unaffected side by lifting the heel with one hand while preventing knee flexion with the other. □ With the knee flexed, check that passive hip flexion is normal. If there is still doubt as to whether there is sciatic nerve root irritation, for example where malingering is suspected, other manoeuvres may be tried, such as the 'flip test' (Fig. The 'bowstring sign' is another useful test and may be tised to confirm nerve root irritalion. 8.12).Īdditional tests are sometimes useful. The roots can be stretched by extending the hip with the knee flexed ( femoral nerve stretch test) (Fig. The femoral nerve passes into the thigh anterior to the pubic ramus, ant! hip flexion or straight leg raising will relieve any tension on these roots. There may also be altered sensation over the anteromedial aspect of the thigh. This may cause weakness of the quadriceps muscles, resulting in reduced power of extension at the knee, sometimes associated with a reduced knee jerk (元/4). Less frequently, disc prolapse at high levels may occur, involving the L2, 元 or L4 roots of the femoral nerve.

When the root is stretched over a prolapsed disc, straight leg raising will be restrictedĪnd pain will usually be felt in the lumbar region, not just in the leg (Fig, 8,1 IB). Normally, about 90 degrees of hip flexion should be possible but this varies considerably (70-120 degrees). Tension can be applied to these nerve roots by flexing the hip with the knee straight -the so-called straight leg raising test. Prolapse of intervertebral discs occurs most frequently at the L4/5 or L5/SI level, producing compression of the L5 and SI nerve roots respectively.

Straight leg raise test for sciatica