Table 2.

Maximal pressure, total contrast volume and both pressure and contrast volume at initial evoked pain at discography

	Disc Nr	Min	Max	Mean	SD
Total contrast volume	107	0.6	3.5	1.8	0.6
Volume at initial evoked pain	96	0.1	2.5	0.7	0.4
Maximal pressure	119	10	127	43	25
Pressure at initial evoked pain	94	3	72	24	16

Due to technical and human factors (invaluable figures, when doubt existed if pain was evoked etc.) all parameters were not registered in every disc. Volume is given in ml and pressure in pounds per square inch (psi)

SD Standard deviation