Doctors and therapists have very little success finding an exact cause for many patients’ back pain. Without a known cause of pain and dysfunction, everyone gets lumped into one big group. Finding the right treatment is a challenge without a clear diagnosis.
Some researchers think patients with low back pain can be put into subgroups. One of those groups is called lumbar segmental instability (LSI). Each spinal segment has an ideal amount of passive and active motion. With LSI the spine doesn’t move within this range. Active motion comes from the spinal muscles. Passive movement is supplied by the elastic stretching of discs, ligaments, and joints. Too much motion at any segment can cause extra wear and tear, pain and deformity, or pressure on the spinal nerves.
Patients with LSI may get better with a specific rehab program. Therapists think it’s a good idea to identify these patients early on. In this study, physical therapists checked how reliable tests are for LSI when more than one person does the test. A reliable test means the same response is seen no matter who does the test. And the same result is observed each time the test is given.
Tests included trunk motion, joint laxity, and two special tests: the posterior shear and prone instability tests. The therapists also looked at segmental mobility testing. They rated each patient as normal, hypomobile (too little motion), or hypermobile (too much motion).
They found ligament testing and the prone instability test were the most reliable for LSI. Observing trunk motion was also a reliable test. The posterior shear test had fair reliability. Segmental mobility testing had the poorest reliability. The authors suggest reasons for the poor results with segmental mobility testing. They think it may be due to how hard it is to know what lumbar level is being tested. Lack of training in conducting the test may also be a factor.
The authors conclude that therapists can expect to get similar results every time when using the three most reliable tests for LSI. They say the next step is to look for tests that are valid, meaning that the test really shows if LSI is (or isn’t) present.