Lower Back Pain
Lower back pain is a very common complaint. The life time prevalence of an episode of lower back pain is 80%. Many of these episodes are relatively transient in nature and the exact cause of the pain will never be known. However, there are important causes of back pain that need to be identified. History is extremely important. There are so called “red flags” that need to be identified. Simialarly there are “yellow flags” that need to be identified. (table of red and yellow flags)
Comment about the quality of the pain??
The examination of the lower back usually begins with the patient sitting in a chair. Note if the patient is sitting comfortably or whether they are in pain. Ask the patient to stand from the chair. If they require than arm rests to stand up then ask the patient to try again but this time not to use the arm rests. An inability to this is suggestive of proximal muscle weakness but can be due to severe lower back pain.
Causes of back pain – can we ask for permission to use the Klippel and Dieppe table?
Ask the patient to stand with their back towards the examiner. Look carefully at the back. Look for a scoliosis, loss of lumbar lordosis or kyphosis.
Next palpate the spine. Initially palpate from the lower thoracic vertebrae towards the scarum. Palpate each vertebral body individually for tenderness. Palpate the sacrum then palpate the sacro-iliac joints. These are best felt below the dimples of venus. Next palpate the paraspinal muscles for tenderness and spasm. Palpate along the posterior iliac crest again for muscle tenderness and spasm.
Test spinal movements. Begin with forward flexion. Ask the patient to keep their knees extended and to try and touch the ground. With hypermobility the patient will be able to place their hands flat on the ground. With disease of the lower spine there is limitation of flexion. The distance between the floor and the fingertips should be noted. Test lateral flexion. Ask the patient to slide their hand down the outside of their leg. Their fingertip should be able to reach the lower aspect of the patella. With nerve root compression the patient will have pain down the leg on the same side as the lateral flexion. Pain on the opposite side to flexion is often muscular.
Test extension. Stand behind the patient and ask the patient to lean back. Ask the patient to stand straight again. Then ask the patient to rotate 45° in one direction and then lean back. Pain that is elicited in the lumbar spine is suggestive of zygophyseal joint disease. Do this again with the patient rotated in the opposite direction.
A more objective measure of lumbar flexion is with the schober’s test. (diagram). With the patient standing, place a tape measure along their lumbar spine. Mark a position 10cm above the level of the dimples of venus. Firmly hold the tape measure at the distal end of the spine. Ask the patient to flex forwards with their knees extended. At maximal flexion the 10cm mark should be at least 15cm.
Test quickly for muscle weakness. Ask the patient to stand of their toes. Inability to do this suggests calf weakness which could be a L5 or S1 nerve root lesion. Ask the patient to stand on their heals. Patients are often unsteady but a foot drop will be obvious.
The patient must then be assessed for a specific nerve lesion. The neurological examination of the lower limb is covered else where.