Joseph D. Fortin

The prevalence and clinical features of internal disc disruption in patients with chronic low back pain.

Study Design This was a cross-sectional analytic study of patients with chronic low back pain. Objective To investigate whether the criteria for internal disc disruption, as adopted by the International Association for the Study of Pain, could be satisfied in patients with chronic low back pain and to test whether there were any conventional clinical features that could identify this condition. Summary of Background Data Internal disc disruption has been postulated as an important cause of low back pain. To diagnose this condition, the International Association for the Study of Pain taxonomy requires that pain be reproduced on provocation discography and that computed tomography discography reveal internal disc disruption, provided that as a control, stimulation of at least one other disc fails to reproduce pain. Methods Ninety-two consecutive patients with chronic low back pain and no history of previous lumbar surgery were studied. Each patient underwent a standard physical examination. Computed tomography discography was performed at a minimum of two levels. Results The diagnostic criteria for internal disc disruption were fully satisfied in 39% of patients, most commonly at L5-S1 and L4-L5. None of the clinical tests used could differentiate between those patients with internal disc disruption and other patients. Conclusions A diagnosis of internal disc disruption can be made in a significant proportion of patients with chronic low back pain, but no conventional clinical test can discriminate patients with internal disc disruption from patients with other conditions.

Clinical features of patients with pain stemming from the lumbar zygapophysial joints. Is the lumbar facet syndrome a clinical entity

Study Design This study is a prospective cross-sectional analytic study. Objectives The authors determined the prevalence and clinical features of patients with pain stemming from the lumbar zygapophysial joints. Summary of Background Data Previous studies have demonstrated a wide range of prevalence for zygapophysial joint pain and conflicting results with regard to clinical signs. Methods One hundred and seventy-six consecutive patients with chronic low back pain were investigated with a series of screening zygapophysial joint blocks using lignocaine and confirmatory blocks using bupivacaine. Results Forty-seven percent of patients had a definite or greater response to the screening injection at one or more levels but only 15% had a 50% or greater response to a confirmatory block. Response to zygapophysial joint injection was not associated with any single clinical feature or set of clinical features. Conclusions The zygapophysial joint is an important source of pain but the existence of a “facet syndrome” must be questioned.

The relative contributions of the disc and zygapophyseal joint in chronic low back pain.

Study Design. A prospective cross-sectional analytic approach was taken. Objectives. This study sought to determine the relative contribution of the disc and the zygapophyseal Joint as a pain source in patients with chronic low back pain. Summary of Background Data. Previous studies have employed either zygapophyseal joint blocks or discography, but in no studies have both procedures been performed. Methods. Ninety-two consecutive patients with chronic low back pain were studied using both discography and blocks of the zygapophyseal joints. Results. Thirty-six patients (39%) had at least one positive discogram as defined by exact pain reproduction, an abnormal image, and a negative control. Eight patients responded to both a screening zygapophyseal joint block using lignocaine and confimatory block using bupivacaine. Only three patients had both a positive discogram and a symptomatic zygapophyseal joint. Conclusions. In patients with chronic low back pain, the combination of discogenic pain and zygapophyseal joint pain is uncommon.

Histologic analysis of neural elements in the human sacroiliac joint

Study Design. The posterior ligament of the human sacroiliac joint was examined for nerves and nerve endings using histologic and immunohistochemical techniques. Objective. To identify nerve fibers and mechanoreceptors in the posterior ligament. Summary of Background Data. According to the findings of previous studies, the human sacroiliac joint receives myelinated and unmyelinated axons that presumably conduct pain and proprioceptive impulses derived from mechanoreceptors and free nerve endings in the human sacroiliac joint. Methods. Tissue obtained from six patients was stained with gold chloride and that obtained from six additional patients was stained using antibodies specific for substance P and protein gene product 9.5. Results. The staining of joint tissue using the gold chloride technique showed myelinated and unmyelinated nerve fibers, two morphotypes of paciniform encapsulated mechanoreceptors, and a single nonpaciniform mechanoreceptor. Analysis using immunohistochemical staining for protein gene product 9.5 did not unequivocally show axons, nerve fascicles, or mechanoreceptors. Similarly, analysis based on immunohistochemical staining for substance P, one of several neurotransmitters known to signal pain from the periphery, showed reactive elements that may have been nerves, but because of background staining, could not be positively identified as such. Conclusions. The presence of nerve fibers and mechanoreceptors in the sacroiliac ligament demonstrates that the central nervous system receives information, certainly proprioceptive, and possibly pain from the sacroiliac joint. Although it is not known how the central nervous system uses such information, it seems reasonable to speculate that the proprioceptive information is used to optimize upper body balance at this joint. In addition, because the staining techniques used generally to show nerves and nerve elements in periarticular connective tissue are nonspecific, the distinction between neural and nonneural should be made on the basis of both morphologic and staining characteristics.

Sacroiliac Joint Dysfunction: A New Perspective

The sacroiliac (SI) joint as a primary source of low back pain is a resurgent, yet controversial subject. In 1905, Goldthwaite proposed that the sacroiliac joint could be a physiologic pain generator independent of pregnancy.1 The role of the sacroiliac joint fell into obscurity over the ensuing decades, with the discovery of such tangible entities (with accepted pathophysiology) as the herniated nucleus pulposus,2 and spinal stenosis.3 Accordingly, there is a paucity of basic and clinical science information available to aid physicians in understanding the biomechanics, diagnosis, and rehabilitation of sacroiliac joint dysfunction.

The frequency of accessory sacroiliac joints

Indiana University School of Medicine, Fort Wayne, IndianaThe accessory sacroiliac joint (ASIJ) is a knownanatomic variant that has been recognized since theearly 1900’s. It is a false joint remote and dorsal tothe true synovial portion of the sacroiliac joint (SIJ).The sacral and iliac components are closely approxi-mated with well-defined and corticated joint marginsas well as a distinct joint space.The etiology of the ASIJ remains unclear. It is notcertain if the ASIJ is a congenital condition or if itis an acquired joint. Petersen (1905) and Jazuta(1929) found hyaline cartilage and joint capsule insome of their specimens, which suggests the ASIJcan be present at birth. Trotter (1937) found fibro-cartilage on the articular surface of most of hercadaveric specimens. She also noted an increasedfrequency of the ASIJ associated with age and con-cluded this joint was acquired in most cases. Prasso-poulos et al. (1999) found that ASIJs were morecommon in the obese and in persons more than 60years of age, suggesting that the joints are acquiredthrough weight-bearing stress.Ehara et al. (1988) identified the ASIJ in 13% (13of 100) of pelvic CT scans obtained for reasons unre-lated to the skeleton and in 16% (9 of 56) of driedskeletons in their investigation.Valojerdy and Hogg (1990) studied dried bonespecimens and identified the ASIJ in 18% of their153 specimens.In a study that examined the type and prevalence ofanatomical variants of the SIJ in patients without SIJdisease on CT exam, Prassopoulos et al. (1999) identi-fiedanASIJin19.1%ofthe534CTscansstudied.The reports of postarthography computerized to-mography (CT) scans as well as the CT scans of 559chronic pain patients undergoing SIJ injections at acomprehensive Pain Management Facility werereviewed to determine the frequency of the ASIJ, aknown SIJ variant. The ASIJ was identified in 20 of559 (3.6%) post arthography CT scans.A summary of these 20 patients can be found inTable 1. There are two patients in the study who hadan ASIJ on both sides but they were at different lev-els, one male and one female. These two patientshad an ASIJ at the level of S2 on the right and S3 onthe left. Figures 1A and 1B demonstrate bilateralASIJs and a right-sided ASIJ, both located at theS2-3 level.Post SIJ arthography/CT of 559 patients revealedan ASIJ frequency of 3.6%. This is a considerablylower rate than previously reported (Ehara et al.,1988; Valojerdy and Hogg 1990; Prassopoulos et al.,1999). The contrasting findings between the currentand previous reports may be attributed to a differ-ence in patient population base (because the sub-jects of our studies were symptomatic patientsundergoing interventional procedures aimed at painalleviation as well as to determine the anatomical in-tegrity of their SIJ and its capsule). Previous authorsmay have mistaken the joint’s known interdigitatingridges and depressions for accessory joints (Bowenand Cassidy, 1981; Vleeming et al., 1990). It is alsopossible that focal areas of degenerative ankylosis, acommon finding after the age of 30 (Resnick et al.,1975; Vogler et al., 1984), were misinterpreted as acongenital variant. Differences in imaging techni-ques/protocols may also have contributed to the dis-parate findings. In contrast to previous studies, ourstudy group was comprised of symptomatic patients:Hence, if the ASIJ was solely an acquired phenom-enon, this study most probably would have found afrequency of ASIJs equal to or exceeding previousreports.Although the ASIJ is not a rare variant, it may notbe as common a finding as prior studies suggested.Normal joint architectural and degenerative changesmasquerading as accessory joints, the patient popu-lation base, and imaging protocols are some varia-bles which may have contributed to the frequencydifferences between this study and other ASIJ vari-ant investigations.

Sacroiliac Joint Dysfunction

The sacroiliac (SI) joint as a primary source of low back pain is a resurgent, yet controversial subject. In 1905, Goldthwaite proposed that the sacroiliac joint could be a physiologic pain generator independent of pregnancy.1 The role of the sacroiliac joint fell into obscurity over the ensuing decades, with the discovery of such tangible entities (with accepted pathophysiology) as the herniated nucleus pulposus,2 and spinal stenosis.3 Accordingly, there is a paucity of basic and clinical science information available to aid physicians in understanding the biomechanics, diagnosis, and rehabilitation of sacroiliac joint dysfunction.

Sacroiliitis and Sacroiliac Joint Dysfunction

Sacroiliac joint pain is a common pain compliant, with up to 30% of patients with low back pain and specifically with certain areas of increased incidence like inflammatory bowl disease and post lumbar fusion. Strategies exist to locally treat these patients, with randomized support.