Sources of sacroiliac region pain: insights gained from a study comparing standard intra-articular injection with a technique combining intra- and peri-articular injection

Experimental pelvic pain facilitates pain provocation tests and causes regional hyperalgesia

The extra-articular sacroiliac joint (SIJ) structure is a potential source for low back and pelvic pain. This study hypothesised that experimental pain induced in a superficial pelvic ligament causes (1) hyperalgesia to pressure, (2) distinct pain referral, and (3) an increased frequency of positive pain provocation tests of the SIJ complex. Thirty healthy subjects (15 females) participated in this study designed as a randomised crossover trial. Pain was induced in the long posterior sacroiliac ligament by injection of hypertonic saline, with the contralateral ligament injected with isotonic saline as control. Pain intensity was assessed on an electronic visual analogue scale (VAS). Pressure pain thresholds (PPTs) and pain provocation tests were assessed on 3 occasions: at baseline, after injection, and when pain had subsided. PPT sites were located bilaterally at the injection site, lateral to spinous processes of S2 and L5, and at the gluteus medius and gastrocnemius muscles. Hypertonic saline caused significantly higher VAS scores and more extended pain referral than isotonic saline (P<0.001). PPTs at the injection site and lateral to S2 were significantly reduced after hypertonic saline compared with baseline and isotonic saline (P<0.002). Significantly more subjects had positive pain provocation tests after hypertonic (67% of subjects) compared with isotonic saline (20%; P<0.001). These data demonstrate that the extra-articular SIJ structure accommodates nociceptors that are capable of inducing pain referral and regional hyperalgesia sensitive to manual pain provocation tests similar to what previously have been found in pelvic girdle pain patients.

Feasibility and accuracy of ultrasound-guided sacroiliac joint injection in dogs

Frozen cadaver specimens from three dogs were used to create a sectional anatomic atlas of the sacroiliac region. Frozen/thawed cadaver specimens from 12 dogs were used to develop an ultrasound-guided sacroiliac joint injection technique. Accuracy of the technique was tested in 15 additional canine cadaver specimens, using injectate containing blue dye and iodinated contrast medium. Sonoanatomic landmarks for consistently identifying a caudodorsal window into the canine sacroiliac joint space included the L7-S1 articular process joints, ilial wing, sacral wing, sacral lamina, and median sacral crest. Accuracy of ultrasound-guided sacroiliac joint injection was not significantly affected by operator, but was affected by the tissue location targeted and the reference standard used for calculations. Accuracy of the technique was good for placing injectate into either the synchondrosis component, dorsal sacroiliac ligament or ventral sacroiliac ligament; fair to poor for placing injectate into the synovial component; and poor for placing injectate into all four sacroiliac soft tissue structures. Concurrent placement of injectate into extraarticular tissues occurred frequently. We conclude that ultrasound-guided sacroiliac joint injection is feasible for evaluation as a treatment method for lumbosacral region pain in dogs, but is not sufficiently accurate for localizing pain to the sacroiliac joint alone.

A randomized, placebo-controlled study to assess the efficacy of lateral branch neurotomy for chronic sacroiliac joint pain

OBJECTIVE

The objective of this study was to compare the efficacy of lateral branch neurotomy using cooled radiofrequency to a sham intervention for sacroiliac joint pain.

DESIGN

Fifty-one subjects were randomized on a 2:1 basis to lateral branch neurotomy and sham groups, respectively. Follow-ups were conducted at 1, 3, 6, and 9 months. Subjects and coordinators were blinded to randomization until 3 months. Sham subjects were allowed to crossover to lateral branch neurotomy after 3 months.

SUBJECTS

Subjects 18-88 years of age had chronic (>6 months) axial back pain and positive response to dual lateral branch blocks.

INTERVENTIONS

Lateral branch neurotomy involved the use of cooled radiofrequency electrodes to ablate the S1-S3 lateral branches and the L5 dorsal ramus. The sham procedure was identical to the active treatment, except that radiofrequency energy was not delivered.

OUTCOME MEASURES

The principal outcome measures were pain (numerical rating scale, SF-36BP), physical function (SF-36PF), disability (Oswestry disability index), quality of life (assessment of quality of life), and treatment success.

RESULTS

Statistically significant changes in pain, physical function, disability, and quality of life were found at 3-month follow-up, with all changes favoring the lateral branch neurotomy group. At 3-month follow-up, 47% of treated patients and 12% of sham subjects achieved treatment success. At 6 and 9 months, respectively, 38% and 59% of treated subjects achieved treatment success.

CONCLUSIONS

The treatment group showed significant improvements in pain, disability, physical function, and quality of life as compared with the sham group. The duration and magnitude of relief was consistent with previous studies, with current results showing benefits extending beyond 9 months.

13. Sacroiliac joint pain

The sacroiliac joint accounts for approximately 16% to 30% of cases of chronic mechanical low back pain. Pain originating in the sacroiliac joint is predominantly perceived in the gluteal region, although pain is often referred into the lower and upper lumbar region, groin, abdomen, and/ or lower limb(s). Because sacroiliac joint pain is difficult to distinguish from other forms of low back pain based on history, different provocative maneuvers have been advocated. Individually, they have weak predictive value, but combined batteries of tests can help ascertain a diagnosis. Radiological imaging is important to exclude "red flags" but contributes little in the diagnosis. Diagnostic blocks are the diagnostic gold standard but must be interpreted with caution, because false-positive as well as false-negative results occur frequently. Treatment of sacroiliac joint pain is best performed in the context of a multidisciplinary approach. Conservative treatments address the underlying causes (posture and gait disturbances) and consist of exercise therapy and manipulation. Intra-articular sacroiliac joint infiltrations with local anesthetic and corticosteroids hold the highest evidence rating (1 B+). If the latter fail or produce only short-term effects, cooled radiofrequency treatment of the lateral branches of S1 to S3 (S4) is recommended (2 B+) if available. When this procedure cannot be used, (pulsed) radiofrequency procedures targeted at L5 dorsal ramus and lateral branches of S1 to S3 may be considered (2 C+).

Evidence-based radiology (part 1): Is there sufficient research to support the use of therapeutic injections for the spine and sacroiliac joints?

INTRODUCTION

This review article addresses the best evidence currently available for therapeutic injection therapy for conditions targeting the spine and sacroiliac joints. The article is presented by spinal region. Controversies and areas of interest for further studies are identified.

DISCUSSION

There is conclusive evidence supporting the effectiveness of the caudal approach for the administration of epidural steroid injections for patients with low back pain from a variety of causes. In general, there is moderate-to-strong evidence supporting the use of transforaminal therapeutic epidural injections for lumbar nerve-root compression and facet injections for joint pain arising from these joints in the cervical, thoracic and lumbar spine, but further subgroup analysis is needed to help predict which specific patients may receive the most benefit from these procedures.

CONCLUSION

No randomized controlled trials, meta-analyses or systematic reviews addressing the effectiveness of therapeutic sacroiliac joint injections have been found. For some injections, corticosteroids may not provide better outcomes compared to local anesthetic injections alone.