Dear Medical Doctors,
Keep saving lives. When you have a patient with non-life-threatening back pain however…refer them to me… OR consider a common but under-diagnosed cause before breaking out the prescription pad. That cause ladies and gentlemen is….
Dynamic Lumbar Instability!
Back pain can be caused as a result of poor coordination of the muscles that stabilize the spine through movements. Sloppy neuromuscular activation patterns of the spinal stabilizers (multifidus, lumbar extensors, transverse abdominus, obliques, rectus abdominus etc.) can develop over time with poor postural habits and while being sedentary. When you don’t have well developed control of the muscles that stabilize the spine, then normal movements can be doing damage to your spinal joints. The perturbed motion patterns that lead to dysfunction most often have to do with the abdominal muscles.
It’s really hard to say how common it is exactly, as back pain is something that has always been very hard for researchers to study. Though it’s safe to say that the experts on spinal biomechanics all agree that functional instability is a real problem and a real source of pain. Moreover there is plenty of good research citing higher rates of poor muscle activation in populations with chronic or recurrent low back pain. There also happens to be decent research to show a decrease in the prevalence of low back pain after stability-based rehabilitation.
What to consider:
Posture, both seated and standing.
The movements that cause pain (flexion, extension, lateral flexion or rotation, ‘glitches’ or cheating in movements).
The prone instability test (72% Sensitivity 58% Specificity)
The active strait leg raise test (tests lumbar rotational stability)
The passive extension test (84% sensitivity 91% specificity)
Keep in mind that pain from lumbar instability is more likely associated with hypermobility (both general and that of the lumbar spine) than with hypomobility.
Lumbar segmental instability can be caused or exacerbated by a spondylolisthesis.
Radiographs can be useful. Lumbar flexion/extension radiographs can reveal a spondylolisthesis, anterolisthesis or a movement-related anterior translation of one vertebrae over another.
Finally consider that lumbar instability is very rehab-able. And best of all, nobody can have too much stability.
Consider exercises like the bird-dog, side-bridge, and front plank on a medicine ball. These exercises develop the endurance of the spinal stabilizers without putting high compression loads through the spine (like a conventional sit up does).