The examination of the low back, like the other areas of the body, should begin as the patient enters the office and examination room. Watch how the patient moves while walking and how he or she moves changing positions. The patient's posture should be noted. The patient should be in a gown that opens in the back for full exposure. Look at the muscle bulk and symmetry of the low back. Also look at the skin for scarring or discoloration. Inspect the lumbar spine from behind and the side to assess for lordosis. Often, patients with stenosis may have hypolordosis because of spinal stenosis. Young athletes might have hyperlordosis because of an imbalance of paraspinal to abdominal strength.
The next step involves palpation of the muscles of the back, spinous processes, and important landmarks of the pelvis. From the back, the paraspinal muscles and the interspinous ligaments can be palpated. Palpate for the spinous processes, and in an older patient, these should be percussed to help in the diagnosis of a compression fracture. Finally, palpate for the bilateral posterior superior iliac spines (PSIS) to determine pelvis alignment. The examiner should place her thumbs on the bilateral PSIS and index fingers on the iliac crests. The height of the pelvis can be checked for alignment by comparing the two sides. Look for symmetry of bulk.
Range of Motion
Range of motion should be tested both actively and actively assisted if possible. Both are important in the evaluation of the low back. Range of motion should be checked in flexion, extension, rotation, and side bending. If there is posterior pain to one side, the examination should include extension to both the left and the right to stress the zygapophyseal joints and to narrow the foramen in a patient with foraminal stenosis or a foraminal disc protrusion.
It is important to watch the spine during motion. In forward flexion, ask the patient to touch his or her toes and watch to see whether the motion comes from the spine or hips. Watch for reversal of the lumbar lordosis by inspecting the prominence of the spinous processes. In extension, look for the motion in the lumbar spine versus the hip and knees in many patients. While assessing range, ask the patient whether the discomfort is greater in flexion or extension. Be aware of conditions that can lead to spinal inflexibility like ankylosing spondylitis or diffuse idiopathic spinal hyperostosis (DISH).
Rotation and side bending can be evaluated next. The patient should be able to rotate his or her shoulders perpendicular to the pelvis. It is often helpful to stabilize the pelvis while the patient is rotating. Have the patient side bend next, and compare it to the opposite side. With each maneuver, the examiner can follow the active motion with active assisted motion to see to what degree the active motion is limited.
Examination of the hip joint and the muscles crossing it is an important part of the lumbar spine examination because of the intimate association with the pelvis and lumbar spine. Limited hip rotation may lead to increased rotatory forces in the spine. A tight rectus femoris may tilt the pelvis anteriorly, increasing the lumbar lordosis, whereas hamstring tightness may tilt it posteriorly and decrease it.
Maybe no other joint in the young person has seen more change in approach over the past few years than the hip. In evaluating the spine, the examiner should have an idea of any suspected loss of range of motion. In the older patient, the loss of range of motion, particularly internal rotation, needs to be documented, and the practitioner needs to determine how much that pain contributes to the patient's symptoms. In a younger patient, the loss of range of motion can be early osteoarthritis, but in the absence of joint space loss on plain film radiographs, it could be a soft tissue injury or a bony anatomy change. Studies have shown that labral tears can be seen in young patients with complaints of groin pain approximately 20% of the time (21). These lesions have a high association with bony abnormalities (22) and could be precursors for osteoarthritis (23).
The examination of the hip should consist of at least three elements. The first standing on one leg or walking to look for dynamic weakness in the form of a lurch to the opposite side or compensation to the same side due to weakness. This can be checked in the side lying position statically. Next, the patient should be supine and simple range of motion should be checked at 90 degrees of hip and knee flexion. Finally, the hip should be checked in flexion at 90 degrees, adduction, and internal rotation for the presence of groin pain. Table 2-6 shows normal range of motion of the hip.
The examination of the low back always includes a full neurologic examination of the lower limbs. Radiculopathies can be very subtle, and as with the cervical spine examination, manual muscle testing, sensory examination, and reflexes all must be addressed to find these subtle changes. The order to proceed is examiner dependent. Similar to the cervical spine examination, manual muscle testing should also be confirmed with additional muscles when subtleties exist because the muscles of the lower limbs have two or more levels of innervation. However, unlike the upper limbs, the lower limb muscles can generate greater force. The examiner needs to provide enough resistance to detect subtle muscle weakness. In addition, heel and toe walking can be added to the gait examination to test the tibialis anterior and gastrocnemiussoleus muscles. Table 2-7 lists what should be included in manual muscle testing (19).
Reflexes can be addressed next. Table 2-8 lists what should be included in reflex testing (19).
Finally, sensation can be tested for both pinprick (lateral spinothalamic tract) and light touch (dorsal columns). Table 2-9 lists what should be included in sensation testing (19).
Examination of the low back should include special tests that are specific for certain pathologies. Every back examination should include a straight leg raise if there is concern about radiculopathy. The straight leg raise, also known as the Lasegue's test, can be performed with the patient seated or in the supine position. With the patient supine, raise the affected lower limb with the knee in full extension. Starting at 30 degrees of leg elevation, patients with nerve root irritation will begin to have discomfort. Stretch on the nerve will be maximal at 65 degrees, and pelvic rotation will begin. A positive test is pain down the limb to the knee in the arc of 35 to 65 degrees. For more subtle cases, ankle dorsiflexion can be added to maximize the nerve stretch.