Back Examination (Thoraco-lumbar)

Low back pain is a very common presentation in general practice. Although the cause and severity of back problems are often fairly clear, it is often essential to make a thorough assessment and detailed examination of the back.

• Observe for abnormal gait and posture, which may provide clues as to the nature and severity of the problem.
• Superficial landmarks include:
  • T1 is the most prominent spinous process at the base of the neck
  • T7/T8: lower border of scapula
  • L4: iliac crests
  • S2: dimples at posterior superior iliac spines
• Assess curvature: kyphosis, scoliosis
• Ask the patient to bend forwards: postural scoliosis resolves, a structural scoliosis does not disappear and therefore needs further assessment. A lumber scoliosis may be associated with a prolapsed intervertebral disc. Disappearance of a scoliosis when sitting suggests that the scoliosis may be secondary to shortening of a leg. Idiopathic scoliosis leads to short stature with the trunk short in proportion to the limbs.
• Ask the patient to extend their lower back. An increased kyphosis which is regular and mobile is found in postural kyphosis. Common causes of a fixed regular kyphosis are senile kyphosis (may be associated with osteoporosis, osteomalacia or pathological fracture), Scheuermann's disease and ankylosing spondylitis. Common causes of an angular kyphosis, with a gibbus or prominent vertebral spine include fracture, tuberculosis or a congenital vertebral abnormality.
• Lumbar curvature: flattening or reversal of the normal lumbar lordosis as in a prolapsed intervertebral disc, osteoarthritis of the spine and ankylosing spondylitis. An increase in the lumbar curvature may be normal or due to spondylolisthesis, or secondary to an increased thoracic curvature or a flexion deformity of the hip.
• Look for any other abnormalities, e.g. cafe-au-lait spots, which may suggest neurofibromatosis, a fat pad or hairy patch suggestive of spina bifida, or scarring suggestive of previous thoracotomy or spinal surgery.
• Functional overlay:
  • Ask the patient to sit up on the couch. A genuine patient will have to flex the knees or they will fall back on the couch with pain.
  • Axial loading: apply pressure to the head. Overlay is suggested if this aggravates the back pain.

• Check for bone tenderness of the spine: tenderness may indicate serious pathology such as infection, fracture or malignancy.
• Ask the patient to lean forwards: tenderness between the spines of the lumbar vertebrae and at the lumbosacral junction and over the lumbar muscles may occur with prolapsed intervertebral disc and mechanical back pain.
• Check for tenderness over the sacroiliac joints. This may also occur in cases of mechanical back pain and with inflammation of the sacroiliac joints.
• A palpable step at the lumbosacral junction may indicate spondylolisthesis.

• Ask the patient to bend forward. Lightly percuss the spine from the root of the neck to the sacrum.
• Significant pain is a feature of infections, fractures and neoplasms.
• An exaggerated response may be a feature of a non-organic problem.

• Flexion:
  • Hip flexion can account for apparent motion in a rigid spine. Flexion may be recorded by the distance between the fingers and the ground (most normal people can reach within 7cm of the floor) or the level that the person can reach (e.g. mid-tibia). The overall flexion is due to a combination of thoracic, lumbar and hip movements, and does not distinguish between them.
  • Schober's test
    • When the spine flexes, the distance between each pair of vertebral spines increases.
    • In the Schober's test, a tape with a 15 cm mark is placed vertically in the midline upwards from the level of the dimples at the level of the posterior superior iliac spines). Mark the skin at 0 and at 15 cm and then ask the patient to flex as far forward as they can.
      Record where the 15 cm mark on the skin strikes the tape. The increased distance along the tape is due only to flexion of the lumbar spine and is normally about 6-7 cm (less than 5 cm should be considered as abnormal).
    • Flexion in the thoracic spine may be measured with the upper point 30 cm from the previous zero mark. Thoracic flexion is normally only about 3 cm.
• Extension:
  • Ask the patient to arch their back; pain and restricted extension is particularly common in prolapsed intervertebral disc and spondylolysis.
  • Maximum range is thoracic 25 degrees and lumbar 35 degrees.
• Lateral flexion:
  • Ask the patient to slide their hands down the side of each leg in turn, and record the point reached, either in centimetres from the floor or the position that the fingers reach on the legs.
  • The contributions of the thoracic and lumbar spine are usually equal.
• Rotation:
  • The patient should be seated and asked to twist round to each side.
  • The normal range is 40 degrees and is almost entirely thoracic; lumbar contribution is 5 degrees or less.
  • Performing the test with the patient's arms folded across their chest gives a more accurate assessment.

• Check the hip joints for range of movement and for pain or limitation. Hip problems may present with predominantly back and buttock pain as well as pain in the groin. A loss of range on internal rotation of the hip is often the earliest sign of hip disease.
• Osteoarthritis of the hip may be clinically confused with low back pain, particularly prolapsed intervertebral disc.
• To assess the sacroiliac joint:
  • With the patient lying prone, elicit sacroiliac joint tenderness by applying firm pressure with one hand over the sacrum and the upper natal cleft.
  • Then flex the hip and knee, and then adduct the hip. Pain may indicate sacroiliac joint involvement, such as in ankylosing spondylitis or Reiter's syndrome.

• This may be particularly relevant in suspected cases of ankylosing spondylitis.
• Check the patient's chest expansion at the level of the 4th interspace.
• The normal range for an adult of average build is at least 6 cm.
• Less than 2.5 cm is considered abnormal.

• Depending on individual presentation, it is essential to consider non-musculoskeletal causes of back pain, e.g. urological, gynaecological, gastrointestinal, aortic aneurysm.
• Assessment of peripheral vascular system in lower limbs may be important with patient presenting with leg symptoms, to evaluate peripheral vascular disease.
• Consider primary malignancy sites which may have metastasised to the spine, especially breast cancer, thyroid cancer, renal cancer, prostate cancer and lung cancer.

• Straight leg raising:
  • Passively flex thigh with extended leg while patient is supine. Dorsiflexion of foot helps to elicit pain. Stop when the patient complains of back or leg pain (hamstring tightness is not relevant). The test is negative if there is no pain. Paraesthesiae or pain in root distribution is very significant, indicating nerve root irritation.
  • A positive result on the same side as the pain is said to be about 80% sensitive but only 40% specific; a positive result with the unaffected leg is said to be only 25% sensitive but 75% specific.
  • Back pain suggests but is not indicative of a central disc prolapse, and leg pain suggests a lateral protrusion. Pain must be below the knee if the roots of the sciatic nerve are involved.
  • Lower the leg until pain disappears and then dorsiflex the foot. This increases tension on the nerve roots, aggravating any pain or paraesthesiae (positive sciatic stretch test).
• Bowstring test:
  • Once the level of pain has been reached, flex the knee slightly and apply firm pressure with the thumb in the popliteal fossa over the stretched tibial nerve. Radiating pain and paraesthesiae suggest nerve root irritation.
• Lasegue's sign:
  • With patient supine and hip flexed, dorsiflexion of the ankle causes pain or muscle spasm in the posterior thigh if there is lumbar root or sciatic nerve irritation.
• Femoral stretch test:
  • With the patient prone and the anterior thigh fixed to the couch, flex each knee in turn. This causes pain in the appropriate distributions by stretching the femoral nerve roots in L2-4.
  • The pain produced is normally aggravated by extension of the hip.
  • The test is positive if pain is felt in the anterior compartment of thigh.
• Look for further evidence of neurological involvement:
  • Test the patellar (L3,L4) and achilles (L5,S1) reflexes.
  • Root pressure from a disc may affect myotomes and dermatomes in a selective fashion; record any muscle wasting (compare girths of calf and thigh muscles):
    • Myotomes:
      • L2 and L3: resisted flexion of the hip
      • L4: resisted dorsiflexion of the ankle
      • L5: resisted extension of the big toe
      • S1: resisted eversion of the foot or resisted plantar flexion of the ankle
      • S2: resisted knee flexion
    • Dermatomes: test sensation to pinprick:
      • L2: upper thigh
      • L3: knee
      • L4: medial aspect of the leg
      • L5: lateral aspect of the leg, medial side of the dorsum of the foot
      • S1: lateral aspect of the foot, the heel and most of the sole
      • S2: posterior aspect of the thigh
      • S3-5: concentric rings around the anus, the outermost of which is S3

• This may be assessed by testing the abdominal reflexes. Use a blunt object to stroke the skin in each paraumbilical skin quadrant.
• Failure of the umbilicus to twitch in the direction of the stimulated quadrant suggests cord compression on that side at the appropriate level.
• The muscles of the upper quadrants are supplied by T7-10, and the lower quadrants by T10-L1.

• Ask the patient to place their hands behind their head, flex their knees and sit up.
• Movement of the umbilicus to one side suggests a weakness of the abdominal muscles on the opposite side.
• Possible causes of nerve root compression include an osteophyte, tumour or spinal dysraphism.