1: Spine 2001 Apr 1;26(7):758-64; 

Centralization phenomenon as a prognostic factor for chronic low back pain and disability.

Werneke M, Hart DL.

NovaCare, Southern Ocean Center for Health, Forked River, NJ 08731, USA. mwerneke@juno.com

STUDY DESIGN: Two hundred twenty-three consecutive adults with acute low back pain with or without referred spinal symptoms were treated conservatively and followed prospectively for 1 year. OBJECTIVES: To investigate the predictive value of centralization phenomenon (CP) with psychosocial variables previously identified as important risk factors for patients with acute onset of nonserious or nonspecific low back pain who subsequently develop chronic pain or disability. SUMMARY OF BACKGROUND DATA: Psychosocial factors have been shown to be predictors of chronic disability, but measures from physical examination rarely predict chronic behavior. The authors of the present study investigated whether dynamic assessment of changes in clinical measures during treatment could be used to classify patients and predict occurrence of chronic pain or disability. METHODS: Patients with acute symptoms and no history of surgery were treated by five physical therapists trained in McKenzie evaluation/treatment methods. Seventy-three percent were receiving workers' compensation benefits. At initial evaluation and discharge, 23 independent variables were assessed representing psychosocial, clinical, and demographic factors. Pain location changes to repeated trunk movements were assessed at every visit. Patients were placed in two groups: 1) those with pain that did not centralize and 2) those who completely centralized or demonstrated partial reduction of pain location with time. Treatment was individualized and based on McKenzie methods. Patients were contacted at 12 months after discharge, and dependent variables of pain intensity, return to work status, sick leave at work, activity interference at home, and continued use of health care were assessed. RESULTS: Nine independent variables influenced pain symptoms or disability. Pain pattern classification (noncentralization) and leg pain at intake were the strongest predictive variables of chronicity. CONCLUSION: Dynamic assessment of change in anatomic pain location during treatment and leg pain at intake were predictors of developing chronic pain and disability.

2: Spine 1999 Apr 1;24(7):676-83

A descriptive study of the centralization phenomenon. A prospective analysis.

Werneke M, Hart DL, Cook D.

NovaCare at Southern Ocean Center for Health, Forked River, New Jersey, USA.

STUDY DESIGN: Occurrence and treatment responses associated with the centralization phenomenon were analyzed prospectively in 289 patients with acute neck and back pain with or without referred spinal symptoms. OBJECTIVES: To document symptom changes to mechanical assessment during initial evaluation and during consecutive visits. Using standard operational definitions, patients were categorized reliably into three inclusive and mutually exclusive pain pattern groups: centralization, noncentralization, and partial reduction. It was hypothesized that the occurrence of centralization would be less than previously reported and that the centralization group would have better treatment results. SUMMARY OF BACKGROUND DATA: Centralization has been reported to occur with high frequency during mechanical assessments of patients with acute spinal syndromes. When centralization is observed, a favorable treatment result is expected. Because centralization has not been defined consistently in the literature, the true prevalence and treatment responses associated with centralization have not been confirmed. METHODS: Consecutive patients with neck or back pain syndromes and referred to outpatient physical therapy services were categorized into three pain pattern groups by experienced therapists trained in the McKenzie system. Changes in distal pain location were scored and documented before and after each visit. Maximal pain intensity over 24 hours, perceived functional status, and number of treatment visits were compared between groups. RESULTS: Patients could be categorized reliably according to movement signs and symptoms. The centralization pain pattern group had significantly fewer visits than the other two groups (P < 0.001). Pain intensity rating and perceived function were different between the centralization and noncentralization groups (P < 0.001). There was no difference in treatment response between the centralization and partial-reduction groups (P = 0.306). Prevalence of patients assigned to the three groups was 30.8% in the centralization group, 23.2% in noncentralization, and 46% in the partial-reduction group. CONCLUSION: Categorization by changes in pain location to mechanical assessment and treatment allowed identification of patients with improved treatment outcomes and facilitated planning of conservative treatment of patients with acute spinal pain syndromes. If a proximal change in pain location is not observed by the seventh treatment visit, the results of this study support additional medical evaluation for physical or nonphysical factors that could be delaying quick resolution of the acute episode.

3: Spine 1995 Dec 1;20(23):2513-20; discussion 2521

The centralization phenomenon. Its usefulness as a predictor or outcome in conservative treatment of chronic law back pain (a pilot study).

Long AL.

Columbia Rehabilitation Centre, Calgary, Alberta, Canada.

STUDY DESIGN. Two-hundred-forty-three patients with chronic low back pain were studied in a prospective comparative survey to determine whether the "centralization phenomenon" was associated with outcome after an interdisciplinary work-hardening program. OBJECTIVE. The hypothesis was that patients who demonstrated centralization during initial mechanical assessment would have better outcomes than noncentralizers. SUMMARY OF BACKGROUND DATA. Overall, subjects had decreased pain intensity ratings (mean 20%), increased lifting ability (6-8 kg), and a 59.2% return-to-work rate at a mean of 9.7 months follow-up. METHODS. Patients were classified as either centralizers or noncentralizers, based on results of their initial assessment. Changes in pain ratings, one-time maximal weights lifted, Oswestry scores, and return-to-work status were compared between groups. RESULTS. The centralizers reported significant decreases in their maximum pain ratings (centralizers, 16%; noncentralizers, 6%) and had a higher return-to-work rate (centralizers, 68%; noncentralizers, 52%) than the noncentralizers. CONCLUSION. Centralization can help identify sub-groups within the population with chronic low back pain and could be a useful goal setting and case management tool in the rehabilitation of low back pain.

4: Spine 1990 Mar;15(3):211-3

Centralization phenomenon. Its usefulness in evaluating and treating referred pain.

Donelson R, Silva G, Murphy K.

Department of Orthopaedics, State University of New York, Syracuse.

In patients with low-back and radiating leg pain, a clinical phenomenon has been described known as "centralization," which occurs during a mechanical evaluation protocol described by McKenzie. Relocation of the most distal pain in a proximal or central direction characterizes the pain behavior when patients are assessed in this fashion. Centralization typically occurs rapidly and can be maintained. In a review of 87 such patients, centralization occurred in 76 (87%). Its occurrence during initial mechanical evaluation is a very accurate predictor of successful treatment outcome and reliably determines the appropriate direction of treatment exercise. Nonoccurrence of centralization accurately predicts poor treatment outcome and was a helpful early predictor of the need for surgical treatment.