Abstract
Introduction: Recent cadaveric studies have identified neovascularisation and neoneuralisation as probable mechanisms in the causation of discogenic pain. Calcium pyrophosphate deposits have been observed in discs in several studies. Their significance in the causation of discogenic pain is unclear. Direct correlation between the pain site and histological features can be verified by aware state endoscopic visualisation.
Aim and Objectives: The study aims to examine and correlate the presence of neovascularisation, crystalline pyrophosphate deposits in the disc, and discogenic pain by spinal probing and discography under endoscopic visualisation.
Material and Methods: Tissue removed from intervertebral discs of 224 patients during surgery was examined directly, and polarised microscopy was used to identify the presence of calcium pyrophosphate and neovascularisation. Their presence was correlated to diagnostic provocative findings of spinal probing and discography and intradiscal distortion during aware state endoscopy.
Results: Calcium Pyrophosphate: Twenty out of 224 patients (9%) demonstrated calcium pyrophosphate in the discs. Fourteen had pain reproduced on probing or discography. Thirteen out of 20 patients (65%) had either an annular collection or leak at the index level. 6 had an extradiscal cause of pain. One hundred percent of the patients with annular collections or leaks had pain on spinal probing or discography. Sixteen patients with pyrophosphate deposits did not have neovascularisation.
Neovascularisation: Thirty seven out of 224 patients (16.5%) showed neovascularisation in the disc. Four discs had crystalline pyrophosphate deposits. Thirty three out of 37 (90%) had pain on probing and/or discography. Out of four patients who had no pain on probing or discography, two had demonstrated tears during previous discographic procedures which were treated with laser annealing. These patients had disc bulges and compressive radiculopathy.
Conclusion: The presence of pyrophosphate in the disc without a tear or leak does not directly render them tender to provocation. The presence of pyrophosphate is not correlated to neovascularisation. Annular tears or leaks are not directly correlated to the presence of pyrophosphates. There is a high correlation between pain provocation and neovascularisation.
The abstracts were prepared by Dr P Dolan. Correspondence should be addressed to him at the British Orthopaedic Association, Royal College of Surgeons, 35-43 Lincoln’s Inn Fields, London WC2A 3PN.
