Muscle Control and Non-specific Chronic Low Back Pain

Abstract

Objectives: Chronic low back pain (CLBP) is the most prevalent of the painful musculoskeletal conditions. CLBP is a heterogeneous condition with many causes and diagnoses, but there are few established therapies with strong evidence of effectiveness (or cost effectiveness). CLBP for which it is not possible to identify any specific cause is often referred to as non-specific chronic LBP (NSCLBP). One type of NSCLBP is continuing and recurrent primarily nociceptive CLBP due to vertebral joint overload subsequent to functional instability of the lumbar spine. This condition may occur due to disruption of the motor control system to the key stabilizing muscles in the lumbar spine, particularly the lumbar multifidus muscle (MF).

Methods: This review presents the evidence for MF involvement in CLBP, mechanisms of action of disruption of control of the MF, and options for restoring control of the MF as a treatment for NSCLBP.

Results: Imaging assessment of motor control dysfunction of the MF in individual patients is fraught with difficulty. MRI or ultrasound imaging techniques, while reliable, have limited diagnostic or predictive utility. For some patients, restoration of motor control to the MF with specific exercises can be effective, but population results are not persuasive since most patients are unable to voluntarily contract the MF and may be inhibited from doing so due to arthrogenic muscle inhibition.

Conclusions: Targeting MF control with restorative neurostimulation promises a new treatment option.

Keywords: Arthrogenic muscle inhibition; chronic low back pain; lumbar multifidus; motor control exercises; restorative neurostimulation.

Figure 1

Model of spine stability.

Figure 2

Dissection, digitization, and three‐dimensional modeling of lumbar multifidus, lateral views. a. Dissection of superficial (red), intermediate (yellow), and deep (purple) regions. b–f. Segments of the superficial region attaching to L1–L5 spinous processes. g. Three dimensional reconstruction of the digital specimen shown in a. h. Segments of the intermediate region attaching to the L1–L4 spinous processes. Note that there is no intermediate fascicle of the MF attaching to the spinous process at L5. i. Segments of the deep region attaching to the L1–L5 laminae. j. Regions of the LMT attaching to the L5 spinous process. LMT, lumbar multifidus; sp, spinous process; mp, mammillary process; tp, transverse process; PSIS, posterior superior iliac spine; L, lumbar. Reproduced from Rosatelli 20 with permission.

Figure 3

Examples of T1 weighted MRI images of lumbar spine at L3 showing mild (<10%), moderate (10–50%) and severe (>50%) fat infiltration of the lumbar multifidus muscle (images from subjects enrolled in the ReActiv8‐B Clinical Trial with permission).

Figure 4

Compromised spine stability.

Figure 5

Positioning for starting the Prone Instability Test. We obtained consent for inclusion of the photo from the patient.

Figure 6

Activation condition for the PIT (note feet are lifted slightly off the floor). We obtained consent for inclusion of the photo from the patient.