In Pursuit of the Optimal Performance of Radiofrequency Ablation of the Nerves Supplying the Posterior Sacroiliac Joint Complex.

Typical standard of care for these patients is initial visit followed by two diagnostic blocks ((0.5 ml) of 1 % Lidocaine per level). They are asked to complete the pain diary and if they experience a 75% or more decrease in the NRS, they are scheduled for Cooled RFA of the lateral branches of S1, S2, and S3 dorsal rami nerves and of the dorsal ramus of L5 nerve.

If patients do not experience adequate pain relief after either of these injections, it is determined that the cooled RFA procedure will not work for them. Therefore, if they fail to receive adequate pain relief after either of these two injections, they will exit the study and other alternatives will be explored. The patient will also exit the study if they fail to achieve success 1 month after RFA treatment. The treatment of the study patients will not deviate from the standard of care.

• All study Patients

• Visit 1 - Initial Visit During the initial visit, the eligible patients will undergo a routine physical examination where it will be determined if the subject is eligible for the study. If eligible, the physician will explain the study and determine if subject is interested. Informed consent will then be obtained and the patient will be scheduled for the first fluoroscopy-guided diagnostic block with 0.5 ml of 1% Lidocaine of the lateral branches of S1, S2, and S3 dorsal rami nerves and of the dorsal ramus of the L5 nerve. The baseline information, including a 3-day average Numeric Rating Scale (NRS) regarding level of pain, the Oswestry Disability Index (ODI), and analgesic consumption will also be obtained during the initial visit.

• Visit 2 - First Diagnostic Block The participant will be asked questions about their level of pain (NRS) and any change in analgesia medications since their last visit. They will then undergo the first fluoroscopy-guided diagnostic block (DB) with 0.5 ml of 1 % Lidocaine per level. A brief physical examination - including a sensory exam of the buttock area - will be performed after the block and the patients will be given a pain diary to complete after the procedure until the pain intensity reaches pre-procedure intensity (see the flowchart attached). The results of the exam will be documented, i.e ; "no sensory deficit" or "sensory deficit to pinprick in the buttock area". Pain diary will require the patients to scale their pain intensity using the NRS on an hourly basis and to document their activities during this period time. This will be done in accordance with the International Spine Intervention Society practice guidelines with respect to the diagnostic blocks as a prerequisite for radiofrequency ablation. (14). A follow-up appointment will be scheduled in 3-5 days after the first set of diagnostic blocks (this appointment will be pre-scheduled in conjunction with the appointment for the first diagnostic block).

• Visit 3 - First Follow-up (3-5 days after first block) The patient will be evaluated, including NRS and analgesia medications, and the pain diary reviewed. If a 75% or more decrease in the NRS is reported for ≥ 2 hours after the procedure, the patient will be scheduled for a second set of fluoroscopy-guided diagnostic blocks (see Module 1). According to the International Spine Intervention Society and most of the major insurers' guidelines, two "positive"diagnostic blocks are necessary in order to proceed to RFA. If the first diagnostic block doesn't provide temporary ≥ 75% pain relief, the patient will exit the study.

• Visit 4 - Confirmatory Block The participant will be asked questions about their level of pain (NRS) and any change in analgesia medications since their last visit. They will then undergo the second fluoroscopy-guided diagnostic block with 0.5 ml of 1 % Lidocaine per A brief physical examination - including a sensory exam of the buttock area - will be performed after the block and the patients will be given a pain diary to complete after the procedure until the pain intensity reaches the baseline (see the attached flowchart). The results of the sensory exam will be documented, i.e ; "no sensory deficit" or "sensory deficit to pinprick in the buttock area". This will be done in accordance with the International Spine Intervention Society practice guidelines with respect to the diagnostic blocks as a prerequisite for radiofrequency ablation. (14). A follow-up appointment will be scheduled in 3-5 days after the second set of diagnostic blocks (this appointment will be pre-scheduled in conjunction with the appointment for the second diagnostic block).

• Visit 5 - Second Follow-up (3-5 days after 2nd block) The patients will be evaluated again at their second follow-up appointment, including NRS and analgesia medications, and the pain diary reviewed. If this block is "negative," the patient will exit the study after the follow-up and will be treated by alternative methods; if it is "positive", the patient will be scheduled for a Cooled RFA.

• Visit 6 - Cooled RFA These subjects that experienced a "positive" response to two sets of diagnostic blocks will undergo Cooled RFA of the lateral branches of S1, S2, and S3 dorsal rami nerves and of the dorsal ramus of L5 nerve as described by Kapural et al. (15). All patients will be evaluated for buttock hypoesthesia immediately after the intervention.

• Visit 7 - 1 Month Follow-up after Cooled RFA At this time, the following data will be collected: 3-day average NRS scores, satisfaction with the treatment, ODI, and analgesic consumption. Physical evaluation, including sensory exam of the buttock area will be done. If the procedure is successful (NRS scores improvement by ≥ 50% and satisfaction with the treatment) the patients will be scheduled for the second and final follow-up at 6 months post-intervention. Otherwise, they will exit the study.

• Visit 8 (Final) - 6 Month Follow-up after Cooled RFA At this time, the following data will be collected: 3-day average NRS scores, satisfaction with the treatment, ODI, and analgesic consumption. Physical evaluation, including sensory exam of the buttock area will be done.

• Data to be collected The following data will be collected for each patient: Name, MRN, date of visit, NRS scores, ODI information, concomitant meds, pain diary, treatment satisfaction, and sensory exam info.