High-frequency thermal coagulation to treat middle cluneal nerve entrapment neuropathy.

OBJECTIVE: Middle cluneal nerve entrapment (MCN-E) around the sacroiliac joint can elicit low back pain (LBP). Pain control can be obtained with anesthetic nerve blocks; however, when their effectiveness is transient, surgical release may be necessary. We investigated the efficacy of radiofrequency thermocoagulation (RFTC) in patients with MCN-E. METHODS: Between December 2018 and August 2019, 11 consecutive patients (4 men, 7 women; mean age 76.4 years) with intractable medial buttock pain due to MCN-E underwent MCN RFTC. The mean symptom duration was 49.5 months; pre-RFTC local MCN blocks provided pain relief for a mean of 7.7 days. The severity of pain in the medial buttock due to MCN-E was recorded before and 2, 6, 12, and 24 weeks after RFTC on the numerical rating scale (NRS) and the Roland-Morris Disability Questionnaire (RDQ). RESULTS: All patients reported pain alleviation; there were no complications. While there was a significant difference in the pre- and post-RFTC treatment NRS (p < 0.05), the RDQ scores were significantly lower only after 12 weeks. The duration of pain relief was significantly prolonged by RFTC (p < 0.05). Two patients suffered pain relapse 10 weeks post-RFTC; pain alleviation was obtained by re-RFTC performed 2 weeks after pain recurrence. Two other patients relapsed 20 and 21 weeks post-RFTC; their symptoms also disappeared by MCN block administered 24 weeks after they had undergone RFTC. CONCLUSION: RFTC may safely control intractable LBP due to MCN-E.

Cost-Effectiveness of Radiofrequency Denervation for Patients With Chronic Low Back Pain: The MINT Randomized Clinical Trials.

OBJECTIVES: To evaluate the cost-effectiveness of radiofrequency denervation when added to a standardized exercise program for patients with chronic low back pain. METHODS: An economic evaluation was conducted alongside 3 pragmatic multicenter, nonblinded randomized clinical trials (RCTs) in The Netherlands with a follow up of 52 weeks. Eligible participants were included between January 1, 2013, and October 24, 2014, and had chronic low back pain; a positive diagnostic block at the facet joints (n = 251), sacroiliac (SI) joints (n = 228), or a combination of facet joints, SI joints, and intervertebral discs (n = 202); and were unresponsive to initial conservative care. Quality-adjusted life-years (QALYs) and societal costs were measured using self-reported questionnaires. Missing data were imputed using multiple imputation. Bootstrapping was used to estimate statistical uncertainty. RESULTS: After 52 weeks, no difference in costs between groups was found in the facet joint or combination RCT. The total costs were significantly higher for the intervention group in the SI joint RCT. The maximum probability of radiofrequency denervation being cost-effective when added to a standardized exercise program ranged from 0.10 in the facet joint RCT to 0.17 in the SI joint RCT irrespective of the ceiling ratio, and 0.65 at a ceiling ratio of €30 000 per QALY in the combination RCT. CONCLUSIONS: Although equivocal among patients with symptoms in a combination of the facet joints, SI joints, and intervertebral discs, evidence suggests that radiofrequency denervation combined with a standardized exercise program cannot be considered cost-effective from a societal perspective for patients with chronic low back pain originating from either facet or SI joints in a Dutch healthcare setting.

Comprehensive anatomical and immunohistochemical review of the innervation of the human spine and joints with application to an improved understanding of back pain.

BACKGROUND: Pain of spinal origin contributes significantly to cervical, thoracic, and lower back pain presentations. Such pain originates in the nerve fibers supplying the joints or the surrounding ligaments and intervertebral discs. Although there has been little detailed discussion of spinal bony innervation patterns in the literature, the clinical implications of these patterns are anatomically and medically significant. METHODS: The present review provides a detailed analysis of the innervation of the spine, identifying the unique features of each part via online search engines. CONCLUSIONS: The clinical implications of these various studies lie in the importance of the innervation patterns for the mechanism of spinal pain. Immunohistochemical studies have provided further evidence regarding the nature of the innervation of the spine.

Ultrasound indications for chronic pain management: an update on the most recent evidence.

PURPOSE OF REVIEW: The ability of ultrasound to provide detailed anatomic visualization while avoiding radiation exposure continues to make it an appealing tool for many practitioners of chronic pain management. This review will present the most recent evidence regarding the use of ultrasound-guidance for the performance of interventional procedures in the treatment of chronic pain. RECENT FINDINGS: For a variety of different procedures, studies continue to compare ultrasound-guided techniques to commonly used fluoroscopic or landmark-based techniques. Small, randomized controlled trials are beginning to demonstrate that ultrasound-guided approaches to interventional pain procedures can be as well tolerated and effective as the traditionally used techniques, while providing some potential advantages in terms of decreased radiation exposure, avoidance of vascular structures, and in some cases, improved efficiency and decreased rates of adverse effects. SUMMARY: Despite continued interest in ultrasound-guided techniques for chronic pain management procedures, the evidence is still limited mainly to small, randomized trials and case series. For some procedures, such as stellate ganglion block and peripheral joint injections, recent evidence appears to be tilting in favor of ultrasound-guidance as the preferred technique, though fluoroscopy continues to be a much more reliable method for detection of intravascular uptake of injectate.

The surgical neurovascular anatomy relating to partial and complete sacral and sacroiliac resections: a cadaveric, anatomic study.

PURPOSE: Pelvic and sacral surgeries are considered technically difficult due to the complex multidimensional anatomy and the presence of significant neurovascular structures. Knowledge of the key neurovascular anatomy is essential for safe and effective execution of partial and complete sacral resections. The goal of this anatomic, cadaveric study is to describe the pertinent neurovascular anatomy during these procedures. METHODS: Three embalmed human cadaveric specimens were used. Sacrectomies and sacroiliac joint resections were simulated and the structures at risk were identified. Both anterior and posterior approaches were evaluated. RESULTS: During sacroiliac joint resection, L5 nerve roots are at high risk for iatrogenic injury; the vasculatures at greatest risk are the common iliac vessels and internal iliac vessels with L5-S1 and S1-S2 high sacrectomies. Minor bleeding risk is associated with S2-S3 osteotomy because of the potential to damage superior gluteal vessels. S3-S4 osteotomy presents a low risk of bleeding. Adjacent nerve roots proximal to the resection level are at high risk during higher sacrectomies. CONCLUSIONS: Several sacrectomy techniques are available and selection often depends on the specific case and surgeon preference; nevertheless, anatomic knowledge is extremely important. Considering the highly variable anatomic relations of the vascular bundles, a preoperative evaluation with CT or MRI with vascular reconstruction may be helpful to decrease bleeding risk by preemptively binding the internal iliac vessels in cases where higher tumors are present. To decrease the risk of damaging nerve roots, it is recommended to perform the resection as close to the involved foramina as possible.

Preservation of the contralateral sacral nerves during hemisacrectomy for sacral malignancies.

PURPOSE: This study aimed to evaluate the oncologic and functional outcome of the cases treated with hemisacrectomy through a sagittal plane in the sacrum and simultaneous en bloc resection together with the ipsilateral sacroiliac joint without sacrificing the contralateral sacral nerves and summarize tumor resection techniques and reconstruction strategy. METHODS: En bloc resection of a sacral malignancy with ipsilateral sacroiliac joint and preservation of the contralateral sacral nerves by sagittal hemisacrectomy had been performed in 15 patients. An intra-abdominal aortic balloon was used in all these cases and a combined posterior-anterior approach was adopted. A modified Galveston technique was used to reestablish spinopelvic stability and a nonvascularized fibula autograft was used in selected cases. RESULTS: Contralateral sacral nerves were preserved in all 15 patients. Adequate margins (wide and marginal margin) were accomplished in 10 patients. Local recurrence occurred in seven (47%) patients, and four of these had an inadequate margin. There was no perioperative death. Four (27%) patients had wound problems. No mechanical breakdown occurred until the last follow-up. All the patients were able to walk without the use of a walking aid. Sphincter function was partially preserved in all these patients. At the last follow-up, seven (47%) patients survived without evidence of disease, two (13%) patients lived with disease, and six (40%) patients had died of disease. CONCLUSIONS: This procedure has an oncologic outcome that is similar to that of other high sacrectomy and a much better function outcome. Although demanding, it is indicated in selected patients.

Use of cooled radiofrequency lateral branch neurotomy for the treatment of sacroiliac joint-mediated low back pain: a large case series.

BACKGROUND.: The sacroiliac joint (SIJ) complex has been identified as a common source of chronic low back pain. Radiofrequency (RF) neurotomy has been investigated in recent years as a minimally invasive treatment option for SIJ-mediated low back pain. A number of RF neurotomy methodologies have been investigated, including the use of cooled RF. OBJECTIVE.: To retrospectively evaluate the use of cooled RF lateral branch neurotomy (LBN) to treat chronic SIJ-mediated low back pain in a large European study population. STUDY DESIGN.: The electronic records of 126 patients with chronic low back pain who underwent treatment with cooled RF LBN were identified. Subjects were selected for treatment based on physical examination and positive response (≥50% pain relief) to an intra-articular SIJ block. Cooled RF LBN involved lesioning the L5 dorsal ramus and lateral to the S1, S2, and S3 posterior sacral foraminal apertures. Visual analog scale (VAS) pain scores, quality of life, medication usage, and satisfaction were collected before the procedure, at 3-4 weeks postprocedure (N = 97), and once again between 4 and 20 months postprocedure (N = 105). RESULTS.: When stratified by time to final follow-up (4-6, 6-12, and >12 months, respectively): 86%, 71%, and 48% of subjects experienced ≥50% reduction in VAS pain scores, 96%, 93%, and 85% reported their quality of life as much improved or improved, and 100%, 62%, and 67% of opioid users stopped or decreased use of opioids. CONCLUSIONS.: The current results show promising, durable improvements in pain, quality of life, and medication usage in a large European study population, with benefits persisting in some subjects at 20 months after treatment. These results are consistent with previous study findings on the use of cooled RF to treat SIJ-mediated low back pain.

Are the nerves supplying the anterior sacroiliac joint nociceptive?

BACKGROUND: Sacroiliac joint (SIJ) pain is often difficult to diagnose. Moreover, while its anatomical characteristics have been well studied, its innervation and the contributions of particular nerves remain controversial, especially in relation to posterior joint innervation. To our knowledge, previous studies have not investigated the presence of nociceptive fibres in the nerves innervating the anterior SIJ. MATERIALS AND METHODS: Eight adult cadaveric sides underwent dissection of the anterior SIJ. Adjacent anterior rami were examined for branches to the anterior SIJ. Any branches contributing to the anterior SIJ were measured and then resected. These samples were fixed in formalin and substance P was identified immunohistologically. RESULTS: On all sides, 1-2 small branches (mean diameter of 0.33 mm) arose from the posterior aspect of the L4 anterior ramus (12.5%), the L5 anterior ramus (62.5%), or simultaneously from both the L4 and L5 anterior rami (25%). These branches had a mean length of 13.5 mm. All histological samples contained nerve tissue. All samples of nerve fibres traveling to the anterior SIJ were positive for diffuse substance P reactivity. There were no histological differences between sides or sex. Each of the branches identified as travelling to the SIJ exhibited similar positivity for substance P. CONCLUSIONS: This cadaveric study demonstrates that the anterior SIJ nerve fibres carry pain fibres. This new knowledge has application to patients with SIJ syndrome and to its various treatments including interventional approaches to SIJ pain.

The sacroiliac joint: an overview of its anatomy, function and potential clinical implications.

This article focuses on the (functional) anatomy and biomechanics of the pelvic girdle and specifically the sacroiliac joints (SIJs). The SIJs are essential for effective load transfer between the spine and legs. The sacrum, pelvis and spine, and the connections to the arms, legs and head, are functionally interrelated through muscular, fascial and ligamentous interconnections. A historical overview is presented on pelvic and especially SIJ research, followed by a general functional anatomical overview of the pelvis. In specific sections, the development and maturation of the SIJ is discussed, and a description of the bony anatomy and sexual morphism of the pelvis and SIJ is debated. The literature on the SIJ ligaments and innervation is discussed, followed by a section on the pathology of the SIJ. Pelvic movement studies are investigated and biomechanical models for SIJ stability analyzed, including examples of insufficient versus excessive sacroiliac force closure.

[Effect of the sacroiliac ligament block on intractable low back pain in elderly patients].

BACKGROUND: Lumbar spine disease in the elderly people is complicated by a variety of pathophysiology in the spine and the cause of the pain is unclear. Diagnosis of pain may be difficult in patients with pain in the thigh and groin area. Sacroiliac joint is supporting the trunk and movable joint. We examined the effect of the sacroiliac joint block for intractable low back pain. METHODS: Retrospectively we examined the duration of disease in patients with hip and leg pain visiting the hospital for eight months, and we questioned the site of pain awareness. Newton test, Gaenslen test, Patrick test and Fadire test were carried out for sacroiliac joint pain in patients with at least one positive finding. When performing sacroiliac ligaments block local anesthetics was injected to check the position of the dorsal sacroiliac ligaments under ultrasonic echo whenever possible. The block is performed with the patients prone at a point one finger from the posterior superior iliac spine level at an angle of 30-45 degrees downward toward the outside. Injecting the drugs penetrating the ligament continued to give a feel slightly outward to avoid the iliac Cattelan 23 G needle. We confirmed pain assessment NRS at 11 (0-10), and the improvement of pain was assessed with the change of the NRS on the next return. RESULTS: NRS showed a significant decrease at all points in time before block, their pain decreased gradually. The patients showed NRS improvement of more than 50% of the first block in 15 of 24 patients. CONCLUSIONS: Block at the posterior sacroiliac ligament region significantly reduced pain for chronic intractable low back pain. The block was shown to be effective as a treatment and for diagnosis.

Preliminary Results of Endoscopic Radiofrequency Treatment of the Sacroiliac Joint Syndrome.

BACKGROUND AND STUDY: The sacroiliac joint (SIJ) may be the primary source of pain in 15 to 25% of patients with axial low back pain. Furthermore, 75% of patients who have had fusion surgery develop SIJ pain within 10 years. Treatment options include SIJ blocks, radiofrequency (RF) denervation, and fusion. The RF techniques range from ablation of the nerves supplying the joint, creating lesions to the joint itself, or a combination of both techniques. However, different clinical studies could only identify a limited or, in some cases, no effect in decreasing of pain intensity and duration of the effect. METHODS: In this retrospective study, we selected 23 patients with SIJ pain, with a duration of more than 12 months and a 50% pain reduction on the Numeric Rating Scale (NRS) after diagnostic block. All patients received endoscopic ablation of the medial branch L5/S1 and the lateral branches, exiting the sacral foramina on S1/S2 and S2/S3 on both sides while using only one incision on each side. Telephone interviews were conducted with all patients. The outcome was determined with Odom's criteria, percent reduction NRS, subjective assessment of the patient, and duration of the effect. RESULTS: According to Odom's criteria, 79% of the patients showed acceptable to excellent results and confirmed that denervation helped them to manage their daily lives better. The average pain reduction in the responder group was 57% with an average duration of 13.4 months. CONCLUSION: In this retrospective study, we could demonstrate the practicability and effectiveness of endoscopic SIJ denervation in the treatment of SIJ pain using only one incision for three levels on each side. Further studies should investigate if this procedure is more effective than percutaneous RF.

Evaluation of an Ultrasound-Assisted Longitudinal Axis Lateral Crest Approach to Radiofrequency Ablation of the Sacroiliac Joint.

OBJECTIVE: The aim of the study was to evaluate the effectiveness and procedural characteristics of a novel, ultrasound/fluoroscopically guided technique (longitudinal axis sacroiliac joint radiofrequency ablation) for sacroiliac joint denervation. DESIGN: A single-arm cohort with historical cohort comparison was used in this study. METHODS: Thirty-seven participants underwent longitudinal axis sacroiliac joint radiofrequency ablation after 50% or more pain reduction after diagnostic dual-block criterion. Outcomes were the proportion of participants with 50% or more pain reduction and mean Pain Disability Quality of Life Questionnaire change. Subanalysis included longitudinal axis sacroiliac joint radiofrequency ablation procedural and fluoroscopy times compared with participants previously treated with palisade radiofrequency ablation technique. RESULTS: Primary outcome worst case analysis demonstrated a responder rate of 64.9% (95% confidence interval = 48.8%-78.2%) and 59.5% (95% confidence interval = 43.5%-73.7%) at 3 and 6 mos. There was significant decrease in mean Pain Disability Quality of Life Questionnaire at 3 (45.6 ± 9.5 to 21.4 ± 16.0, P < 0.001) and 6 mos (45.6 ± 9.5 to 23.0 ± 16.5, P < 0.001). Longitudinal axis sacroiliac joint radiofrequency ablation required more procedure time than the palisade technique (38.2 ± 7.9 vs. 32.1 ± 6.9 mins, P = 0.031) but less fluoroscopy time (35.0 ± 11.8 vs. 57.6 ± 16.8 secs, P < 0.001). CONCLUSIONS: Longitudinal axis sacroiliac joint radiofrequency ablation resulted in improvement in pain, disability, and quality of life at 3 and 6 mos. Compared with the palisade technique, longitudinal axis sacroiliac joint radiofrequency ablation required greater procedure time but less fluoroscopy time.

Cooled radiofrequency application for treatment of sacroiliac joint pain.

BACKGROUND: The unavailability of an effective and long-lasting treatment for sacroiliac-based pain has led researchers to study the efficacy of radiofrequency in denervation. In this study, we aimed to investigate the efficacy and safety of novel cooled radiofrequency application for sacral lateral-branch denervation. METHODS: Patients experiencing chronic sacroiliac pain were selected for our observational study. Fluoroscopy guidance cooled radiofrequency denervation was applied on the L5 dorsal ramus and the S1-3 lateral branches on patients who had twice undergone consecutive joint blockages to confirm the diagnosis and obtained at least 75% pain relief. At the 1st, 3rd and 6th month postoperatively, the patients' pain was evaluated using a visual analog scale (VAS), and their physical function was evaluated with the Oswestry Disability Index (ODI). RESULTS: Cooled radiofrequency was applied on a total of 15 patients. Prior to the procedures, the median VAS score (interquartile range) was 8 (7-9), but at the 1st, 3rd and 6th month, this had fallen to 3 (1-4), 2 (1-3) and 3 (2-4). The baseline median ODI score (interquartile range) was 36 (32-38), while at the 1st, 3rd and 6th month, it was 16 (8-20), 12 (9-18) and 14 (10-20), respectively. At the final control, while 80% of the patients reported at least a 50% decline in pain scores, 86.7% of those reported at least a ten-point reduction in ODI scores. CONCLUSION: It was seen that the cooled radiofrequency used for sacroiliac denervation was an effective and safe method in the short to intermediate term.

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+).

The ability of multi-site, multi-depth sacral lateral branch blocks to anesthetize the sacroiliac joint complex.

OBJECTIVE: To determine the physiologic effectiveness of multi-site, multi-depth sacral lateral branch injections. DESIGN: Double-blind, randomized, placebo-controlled study. SETTING: Outpatient pain management center. PATIENTS: Twenty asymptomatic volunteers. BACKGROUND: The dorsal innervation to the sacroiliac joint (SIJ) is from the L5 dorsal ramus and the S1-3 lateral branches. Multi-site, multi-depth lateral branch blocks were developed to compensate for the complex regional anatomy that limited the effectiveness of single-site, single-depth lateral branch injections. INTERVENTIONS: Bilateral multi-site, multi-depth lateral branch green dye injections and subsequent dissection on two cadavers revealed a 91% accuracy with this technique. Session 1: 20 asymptomatic subjects had a 25-g spinal needle probe their interosseous (IO) and dorsal sacroiliac (DSI) ligaments. The inferior dorsal SIJ was entered and capsular distension with contrast medium was performed. Discomfort had to occur with each provocation maneuver and a contained arthrogram was necessary to continue in the study. Session 2: 1 week later; computer randomized, double-blind multi-site, multi-depth lateral branch blocks injections were performed. Ten subjects received active (bupivicaine 0.75%) and 10 subjects received sham (normal saline) multi-site, multi-depth lateral branch injections. Thirty minutes later, provocation testing was repeated with identical methodology used in session 1. OUTCOME MEASURES: Presence or absence of pain for ligamentous probing and SIJ capsular distension. RESULTS: Seventy percent of the active group had an insensate IO and DSI ligaments, and inferior dorsal SIJ vs 0-10% of the sham group. Twenty percent of the active vs 10% of the sham group did not feel repeat capsular distension. Six of seven subjects (86%) retained the ability to feel repeat capsular distension despite an insensate dorsal SIJ complex. CONCLUSION: Multi-site, multi-depth lateral branch blocks are physiologically effective at a rate of 70%. Multi-site, multi-depth lateral branch blocks do not effectively block the intra-articular portion of the SIJ. There is physiological evidence that the intra-articular portion of the SIJ is innervated from both ventral and dorsal sources. Comparative multi-site, multi-depth lateral branch blocks should be considered a potentially valuable tool to diagnose extra-articular SIJ pain and determine if lateral branch radiofrequency neurotomy may assist one with SIJ pain.

Sacroiliac Joint Ablation Using MR-HIFU.

The sacroiliac joint is the culprit in 15-30% of patients with chronic lumbar back pain. Ablation of the posterior sensory nerves supplying the joint is an established treatment option before arthrodesis. We report the successful application of MR-HIFU in a patient with therapy-refractory pain using the Sonalleve MR-HIFU system. The outpatient procedure was performed under spinal anaesthesia and analgosedation. The ramus dorsalis of L5 as well as the lateral branches of the ramus dorsalis S1-S3 was targeted, and tissue peak temperature per sonication was controlled using MR-thermometry. There were no post-interventional complications. Clinical improvement began 4 days post-intervention with complete resolution of the pain after 1 month.

Randomized placebo-controlled study evaluating lateral branch radiofrequency denervation for sacroiliac joint pain.

BACKGROUND: Sacroiliac joint pain is a challenging condition accounting for approximately 20% of cases of chronic low back pain. Currently, there are no effective long-term treatment options for sacroiliac joint pain. METHODS: A randomized placebo-controlled study was conducted in 28 patients with injection-diagnosed sacroiliac joint pain. Fourteen patients received L4-L5 primary dorsal rami and S1-S3 lateral branch radiofrequency denervation using cooling-probe technology after a local anesthetic block, and 14 patients received the local anesthetic block followed by placebo denervation. Patients who did not respond to placebo injections crossed over and were treated with radiofrequency denervation using conventional technology. RESULTS: One, 3, and 6 months after the procedure, 11 (79%), 9 (64%), and 8 (57%) radiofrequency-treated patients experienced pain relief of 50% or greater and significant functional improvement. In contrast, only 2 patients (14%) in the placebo group experienced significant improvement at their 1-month follow-up, and none experienced benefit 3 months after the procedure. In the crossover group (n = 11), 7 (64%), 6 (55%), and 4 (36%) experienced improvement 1, 3, and 6 months after the procedure. One year after treatment, only 2 patients (14%) in the treatment group continued to demonstrate persistent pain relief. CONCLUSIONS: These results provide preliminary evidence that L4 and L5 primary dorsal rami and S1-S3 lateral branch radiofrequency denervation may provide intermediate-term pain relief and functional benefit in selected patients with suspected sacroiliac joint pain. Larger studies are needed to confirm these results and to determine the optimal candidates and treatment parameters for this poorly understood disorder.

Nociceptive nerve fibers in the sacroiliac joint in humans.

BACKGROUND AND OBJECTIVES: A positive response to sacroiliac joint intra-articular infiltration with local anesthetics is used to confirm sacroiliac joint pain. However, current anatomical and histological knowledge concerning the anatomy of pain perception within the sacroiliac joint intra- and peri-articular structures is insufficient to explain the efficacy of this infiltration, because of the use of unspecific histochemical visualization techniques. METHODS: In this study, immunohistochemistry for calcitonin gene-related peptide (CGRP) and substance P was used to trace nociceptive fibers and receptors in the anterior and interosseous sacroiliac ligaments obtained from 5 human cadavers without history of sacroiliac joint pain. RESULTS: Microscopic analysis of stained slides showed presence of CGRP and substance P immunoreactive fibers. Thick, wavy, formed bundles were observed in dense and loose connective tissue, whereas single, beaded nerve fibers, occasionally ramified, were observed more frequently in the dense connective tissue and next to blood vessels. Based on their morphologic features, these immunoreactive structures were classified as receptors type IV. Additionally, receptors type II were found in anterior and interosseous ligaments, which contained CGRP or substance P immunoreactive free nerve endings. CONCLUSIONS: We conclude that the presence of CGRP and substance P immunoreactive fibers in the normal anterior capsular ligament and interosseous ligament provides a morphological and physiological base for pain signals originating from these ligaments. Therefore, diagnostic infiltration techniques for sacroiliac joint pain should consider extra- as well as intra-articular approaches.

Structural and biomechanical aspects of equine sacroiliac joint function and their relationship to clinical disease.

Pain originating from the sacroiliac joint (SIJ) in horses has long been associated with poor performance, yet specific diagnosis of sacroiliac dysfunction (SID) has been difficult to achieve. Clinical presentation of SID appears to fall into two categories. The first, presenting as pain and poor performance, is responsive to local analgesia of periarticular structures with poorly defined pathology. The second presents primarily as poor performance with bony pathological changes as a result of chronic instability. Diagnostic tests based on biomechanics as well as manual provocation for SIJ pain have formed the basis of tests currently used to diagnose SIJ dysfunction in humans. This review summarises the anatomy and biomechanics of the equine SIJ and current biomechanical, innervation and motor control concepts in human SID. The relationship between abnormal SIJ motion and altered neuromotor control with clinical disease of the equine SIJ are discussed. Future utilisation of these principles to develop new diagnostic and management tools for the equine SID is promising.