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In Vivo Discography in Degenerate Porcine Spines Revealed Pressure Transfer to Adjacent Discs

Hebelka, Hanna MD*; Nilsson, Andreas MSc; Ekström, Lars BSc; Hansson, Tommy MD, PhD

doi: 10.1097/01.brs.0000435141.61593.05
Biomechanics

Study Design. In vivo experimental porcine study.

Objective. To investigate if discography induced pressure increase in adjacent degenerate discs.

Summary of Background Data. Despite refinements in the past 2 decades, the validity of discography is debated. Discography in healthy pigs has shown that the pressure increase during disc injection transmits to adjacent discs, a potential source for false positive responses.

Methods. Degeneration in 1 lumbar disc was induced in 10 pigs by drilling a hole through the endplate. Intradiscal pressure was recorded using a 0.36-mm fiber-optic pressure transducer inserted into nucleus pulposus through a 22-gauge needle. The pressure was measured simultaneously in 2 adjacent discs during slow (0.03 mL/s) automated contrast injection into 1 of the discs up to 8 bar (116 psi). Ten adjacent discs were prefilled with contrast from previous discogram. A pressure increase 2 psi or more above baseline was defined as increased pressure in adjacent discs. Pressure was recorded until 15 minutes after injection.

Results. A total of 28 discograms were successfully performed. A pressure increase during injection was detected in 57% (16) of the 28 adjacent discs with mean 3.2 psi (1.7–8.2; standard deviation, 1.8), corresponding to a mean increase above baseline of 11%. Of those 16 adjacent discs, 4 were nondegenerate and 12 degenerate, of which 7 were prefilled. Fifteen minutes after injection, 89% of adjacent discs displayed increase in pressure of mean 14% above baseline.

Conclusion. Discography induced pressure increase in adjacent discs in a degenerate disc model, something not reported earlier. If present, also in human spine pressure transmission, may be a potential cause for false positive discography responses.

Level of Evidence: 3

Discography in degenerate porcine spines induced a pressure increase in 57% of adjacent discs with mean 3.2 psi (1.7–8.2). If pressure reactions until 15 minutes after injection were included, 89% of adjacent discs displayed a pressure increase. Pressure transmission might thus constitute a potential validity problem within discography.

*Department of Radiology, Sahlgrenska University Hospital, SU/M, Gothenburg, Sweden; and

Department of Orthopaedics, Sahlgrenska University Hospital, SU/S, University of Gothenburg, Gothenburg, Sweden.

Address correspondence and reprint requests to Hanna Hebelka, MD, Drottning Silvias Barn och Ungdomssjukhus, Barnröntgen, Smörslottsgatan 1, 416 85 Göteborg, Sweden; E-mail: hanna.hebelka@vgregion.se

Acknowledgment date: March 21, 2013. First revision date: July 6, 2013. Acceptance date: August 23, 2013.

The manuscript includes unlabeled/investigational uses of the products/devices listed below and the status of these is disclosed in the manuscript: Sensor for disc pressure measurements, Samba Sensors AB, Gothenburg.

University of Gothenburg (ALF), Sahlgrenska Academy and Gothenburg Medical Society funds were received to support this work.

No relevant financial activities outside the submitted work.

© 2013 by Lippincott Williams & Wilkins