A prospective study of centralization of lumbar and referred pain. A predictor of symptomatic discs and anular competence.

STUDY DESIGN: The presence or absence of rapidly centralizing, peripheralizing, or abolishing low back and radiating pain, as identified during a McKenzie mechanical lumbar assessment of patients with chronic lumbar pain, was compared prospectively with discographic pain provocation and anular competency.

OBJECTIVES: To evaluate any relation between the responses of centralization and peripheralization with discographic findings.

SUMMARY OF BACKGROUND DATA: Centralization of referred pain has been reported as a very common occurrence during McKenzie assessment and treatment. Patients whose pain centralizes have been shown to achieve superior treatment outcomes. A dynamic internal disc model has been hypothesized as an underlying mechanism for centralization that has not been studied previously.

METHODS: Patients with chronically disabling low back pain who were referred for discography underwent preliminary blinded McKenzie clinical assessment and were categorized into three groups by their pain response. Patterns, or lack thereof, of pain response were then compared with blinded discographic pain provocation and anular findings.

RESULTS: During the McKenzie assessment, the referred pain of 50% centralized with 74% having positive discograms, of which 91% had an intact anulus. The pain of 25% peripheralized only (would not centralize); 69% of these had positive discograms, but only 54% had an intact anulus. The distal pain of 25% did not respond at all, and only 12.5% of these had positive discograms.

CONCLUSION: The McKenzie assessment process reliably differentiated discogenic from nondiscogenic pain (P < 0.001) as well as competent from an incompetent anulus (P < 0.042) in symptomatic discs and was superior to magnetic resonance imaging in distinguishing painful from nonpainful discs.