RFN for SIJ Disease Study

Inclusion Criteria: 1. Written, informed consent 2. Age: 18 - 80 years old 3. Low back pain of more than 6 months duration with a minimum pain intensity of greater than 5 out of 10 on an 11-point numerical rating scale in the 7 days preceding study entry. 4. Subjects must achieve greater than 80% reduction in pain following each diagnostic, intra-articular block. Subjects must undergo 2 blocks in total prior to randomisation. 5. Female subjects of potential childbearing age must be using adequate contraception (i.e. using oral or intramuscular contraception or an IUCD) and must have a negative urine test. 6. No vulnerable patient groups shall be recruited into this study Exclusion Criteria: 1. Subjects who do not fulfill inclusion criteria 2. Subjects who have previously been treated by any sacroiliac joint radiofrequency neurotomy 3. Subjects who are breastfeeding 4. Contraindications to local anaesthetics and radiofrequency neurotomy as listed in their respective summary of product characteristics 5. Subjects with documented or suspected alcohol or drug abuse, or who are suspected of having an addictive personality 6. Subjects to whom any of the following apply: Major trauma to the lumbar spine in the six months preceding study entry. Infection in the lumbar spine in the six months preceding study entry 7. Subjects' known to have a condition that, in the investigator's judgment precludes entry into the study. 8. Subjects with a significant psychiatric disorder (including depression) or subjects receiving anti-psychotic medication. 9. Subjects who have received an investigational drug or have used an investigational device in the 30 days preceding study entry. 10. Subjects unable to comply with the study assessments or unable to complete the questionnaires.