Nerve Root Involvement and Symptoms May Predict Treatment Success With McKenzie Method in Chronic Low Back Pain

Spinal extensionCommentary by Tom Petersen, PT, PhD

In a study of patients with chronic low back pain, patients with nerve root involvement and peripheralization of symptoms were more likely to benefit from the McKenzie method over spinal manipulation, according to a randomized controlled trial in BMC Musculoskeletal Disorders.

“Although my preliminary findings need confirmation in larger studies, it seems that when compared to another mobilizing treatment strategy (ie, spinal manipulation), centralization is not a possible treatment effect modifier in favor of the McKenzie method,” said lead author Tom Petersen, PT, PhD, Back Center Copenhagen, Denmark. “However, our study showed that peripheralization is a treatment effect modifier. The explanation for this finding might be that the McKenzie therapists are more capable to give reassurance and guidance of how to modify pain provoking activities because the therapy is based on an assessment of symptom response to movement testing,” Dr. Petersen said.

Patients Were Randomized to McKenzie Method or Spinal Manipulation
The prospective cohort study involved 350 patients (age 18-60 years) with low back pain for more than 6 months who presented with centralization or peripheralization. Centralization was defined as pain ending in distal body regions such as the foot, lower leg, upper leg, buttocks or lateral low back) and peripheralization was defined as production of symptoms in a distal body part.

The patients were randomized to either the McKenzie method or spinal manipulation for up to a maximum of 15 treatments over 12 weeks, and were followed for 2 months thereafter. Success was defined as a reduction of ≥5 points or a final score <5 points on the 23-item modified Roland Morris Disability Questionnaire. In addition, the researchers assessed whether the following factors were predictive of successful outcome with the 2 techniques: age, severity of leg pain, pain distribution, nerve root involvement, duration of symptoms, and centralization of symptoms.

In the spinal manipulation treatment, high-velocity  thrust was used along with other manual techniques at the discretion of the chiropractor. Other exercises that were allowed included general mobilizing exercises, self-manipulation, alternating lumbar flexion/extension movements, and stretching. In addition, wedge seat cushions were used if necessary. Patients in both treatment groups were educated about the benign course of back pain, proper back care, and the importance of remaining physically active.

Greater Treatment Success Found With the McKenzie Method
Overall, the probability of success was greater with the McKenzie method over spinal manipulation. None of the factors assessed were statistically significant predictors of treatment success, which the authors attributed to the low sample size. However, “a clinically important potential effect” in favor of the McKenzie method over spinal manipulation was for nerve root involvement and peripheralization of symptoms. Nerve root involvement was linked to a 2.3 times greater chance of success with the McKenzie method over spinal manipulation. Peripheralization was linked to a 1.8 times greater chance of success with the McKenzie method over spinal manipulation.

“The finding that nerve root involvement is an effect modifier might indicate that spinal manipulation is too aggressive a treatment for an unstable condition,” Dr. Petersen said. “During the course of treatment, some of the patients with symptom peripheralization might respond to exercises in the preferred direction. On the structural level, a plausible hypothesis is that these repeated exercises are able to move some of the nucleus materials that are irritating the nerve root,” Dr. Petersen said.

Updated on: 08/18/16
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