Iliolumbar Ligament Research Articles

Immunohistochemical Demonstration of Nerve Endings in Iliolumbar Ligament

Immunohistochemical study on fresh cadaver specimens. Assessment of mechanoreceptor and nociceptor levels and distribution in iliolumbar ligament. The function of iliolumbar ligament and its role in low back pain has not been yet fully clarified. Understanding the innervation of this ligament should provide a ground which enables formation of stronger hypotheses. Bilateral 30 iliolumbar ligaments of 15 fresh cadavers were included in the study. Morphologic properties were recorded and the ligaments were examined by focusing on 3 main parts: ligament, bone insertions, and tendon body. Assessment of mechanoreceptor and nociceptor levels and their distribution in iliolumbar ligament were performed on the basis of immunohistochemistry using the S-100 antibody specific for nerve tissue. Iliac wing insertion was found to be the richest region of the ligament in terms of mechanoreceptors and nociceptors. Pacinian (type II) mechanoreceptor was determined to be the most common (66.67%) receptor followed by Ruffini (type I) (19.67%) mechanoreceptor, whereas free nerve endings (type IV) and Golgi tendon organs (type III) were found to be less common, 10.83% and 2.83%, respectively. Immunohistochemical staining has shown that iliolumbar ligament had a rich nerve tissue. Those results indicate that ILL plays an important role in proprioceptive coordination of lumbosacral region alongside its known biomechanic support function. Moreover, the presence of type IV nerve endings suggest that the injury of this ligament might contribute to the low back pain.

A Short Report Comparing Outcomes Between L4/L5 and L5/S1 Single-level Discectomy Surgery

Prospective cohort study. To assess whether there is a difference in outcome between single-level discectomy at L4/L5 and L5/S1. There is sound biomechanical reasoning to suspect a difference between spinal levels. The L4/L5 disc is more susceptible to axial torsion and is the most common site of lumbar instability. The L5/S1 motion segment is protected from torsional strain by extensive iliolumbar ligaments but is more exposed to axial compressive forces. The available literature does not include studies with preoperative standard outcome measures. Prospectively gathered data from a single center. The outcome measures were the Oswestry disability index, subjective walking distance, modified somatic perception, modified Zung depression index, low back outcome score, and visual analog score. Comparisons between L4/L5 and L5/S1 levels were made with these outcome measures using the Student t test. Seventy-seven L5/S1 and 53 L4/L5 discectomies were performed. There were no clinically significant differences. Preoperative walking distance for L5/S1 patients was longer than at L4/L5 (455 m vs. 278 m; P=0.027). At 6 months a difference also exists with the low back outcome score [47.11 (L4/L5) vs. 39.47 (L5/S1); P=0.0229]. After 12 months at L5/S1, men had a better Oswestry disability index score than women (17% vs. 32%; P=0.038). Across all other parameters, no significant difference was found to exist between the 2 groups. There was no difference in the recurrence rate or reoperation rate. This is the first study comparing a discectomy outcome at L4/L5 and L5/S1 with complete preoperative data. No significant difference exists between the 2 levels in terms of postoperative outcome. Surgical procedures such as fusion or arthroplasty should not be carried out synchronous with primary discectomy for radiculopathy. The lack of a difference between L4/L5 and L5/S1 reinforces the fact that the mechanical environment does not affect outcome and should not influence treatment.

P130. Disc Degeneration is Increased in Subjects with Spondylolysis at Lumbar Levels Other than L5

BACKGROUND CONTEXT: Disc degeneration has been shown to be higher in patients with spondylolytic defects secondary to decreased stability across the associated disk space. Although spondylolytic defects are most commonly encountered at L5, they do occur less frequently at other lumbar levels, with L4 involvement in up to 12% of cases. The presence of the iliolumbar ligament would be thought to be protective of the L5/S1 disk, thereby limiting disk degeneration in subjects with a spondylolysis at L5.

Iliolumbar Ligament Ossification Demonstrated on Bone Scintigraphy

Horizontally-directed, bilaterally-symmetric, increased linear uptake connecting the L5 vertebra to the iliac crest was incidentally demonstrated on bone scintigraphy in a 51-year-old woman without any radiologic signs or clinical symptoms of spondylitis or arthritis. Plain radiography and computed tomography (CT) revealed ossification of both iliolumbar ligaments in the corresponding sites. This uptake is thought to represent a normal variant on bone scintigraphy.

Disc Height and Lumbar Index as Independent Predictors of Degenerative Spondylolisthesis in Middle-Aged Women With Low Back Pain

A age- and sex-matched case-control radiographic study. To identify the predisposing factors of degenerative spondylolisthesis (DS). None of the radiologic methods for predicting the development of DS are very reliable or readily accessible. The methods commonly used are computed tomography or magnetic resonance imaging. Data were gathered retrospectively on middle-aged women with degenerative lumbar spondylolisthesis. The most common slipped vertebra was L4 (63.64%) and the second was L5 (13.64%). Most parameters, including the disc height, body height, and angle measurements, for the case group tended to be lower than the control group, whereas the transverse process were larger than control group. The differences in disc height, lumbar index (LI), sacral inclination angle (SIA), sacral horizontal angle (SHA), and transverse process between the 2 groups were statistically significant (P < 0.05). Multivariate logistic regression analysis confirmed that anterior inferior disc height (DHIA) and LI were independent variables of predisposing factor to DS and both could explain a 50% variation of DS. Further analysis of the different levels of spondylolisthesis (L4 on L5 vs. L5 on S1 DS) revealed that there was a significant difference in the width of L5 transverse process in L4 on L5 spondylolisthesis (P = 0.03) but insignificant on disc height (P = 0.86). There are 2 independent predictors of DS, decreased anterior disc height and increased lumbar index. The iliolumbar ligament also contributes to the stability of lumbosacral junction, especially in L5 on S1 DS.

Ice Massage Effects On Balance And Lumbar Flexibility In The Patients With Lumbar Sacralization

Patients with LSTV often suffer from low back pain. In this research, ice massage was used as therapeutic intervention, and balance performance and lumbar range of motion were taken as objective assessment for intervention effects. PURPOSE: To evaluate the immediate effect of ice massage on balance and lumbar range of motion in the patients with lumbar sacraliztion. METHODS: Twelve patients (Age: 22.46±1.70 year-old; Body height: 172.42±2.63 cm) who had lumbar sacralization with low back pain received ice massage about the painful region of lumbosacral joints and iliolumbar ligament for 15 minutes. Their balance performance and lumbar range of motion were measured before and after ice massage. Balance performance was measured by Smart Balance Master (Neurocom International Inc., USA), including Sensory Organization Test (SOT), Rhythmic Weight Shifting(RWS) and Limits of Stability(LOS). Lumbar range of motion was measured by microFET3 (HOGGAN Health Industries, USA). RESULTS: In RWS, the on-axis velocity (deg/sec) was significantly improved in Left/Right-Moderate Speed (5.06±0.21 vs. 4.74±0.15, p = 0.015) and Front/Back-Fast Speed (5.81±0.19 vs. 5.12±0.23, p = 0.027) after ice massage, and so was the directional control (%) in Left/Right-Moderate Speed (89.00±0.71 vs. 86.67±0.82, p = 0.033) and Left/Right-Fast Speed (91.50±0.52 vs. 89.00±0.91, p = 0.009). Lumbar range of motion was also improved, though not significant. As for lumbar range of motion, there was no significant difference as well, albeit an increase was observed. CONCLUSION: Balance performance may be used as functional assessment tool for patients with lumbar sacralization. Ice massage improved the rhythmic weight shifting of balance performance in the patients who had lumbar sacralization with low back pain.

Local corticosteroid injections for low back pain and sciatica

In patients with symptoms caused by intervertebral disk displacement, studies of epidural corticosteroid injections have produced compelling evidence of a short-term analgesic effect (lasting about 3 weeks), despite a number of discrepancies. In contrast, no reductions were noted in the time off work or need for surgery. Strong evidence supports a short-term symptomatic effect of guided transforaminal corticosteroid injections, and there is also some evidence of a long-term effect. Further work is needed to assess the potential of this treatment modality for decreasing surgical requirements in patients who fail conventional nonsurgical treatment. Facet-joint injections may produce pain relief in some patients with common low back pain. This modality can be offered to selected patients who fail to respond to first-line treatment. Epidural injections are not appropriate in patients with acute low back pain. They may offer short-term symptom relief to patients experiencing acute exacerbations of chronic low back pain, in whom they are used as an ancillary method. Intradural injections should not be performed, as they may induce adverse effects and have not been proved effective. Interspinous injections and iliolumbar ligament injections can be considered in selected patients. Although published data have led to controversy about the effectiveness of local corticosteroid injections, a short-term analgesic effect is usually obtained, making this modality useful for the second-line treatment of patients with disk-related sciatica, as well as in selected patients with chronic low back pain.

Skeletal Fluorosis From Instant Tea

Skeletal fluorosis (SF) can result from prolonged consumption of well water with >4 ppm fluoride ion (F(-); i.e., >4 mg/liter). Black and green teas can contain significant amounts of F(-). In 2005, SF caused by drinking 1-2 gallons of double-strength instant tea daily throughout adult life was reported in a 52-yr-old woman. A 49-yr-old woman developed widespread musculoskeletal pains, considered fibromyalgia, in her mid-30s. Additionally, she had unexplained, increasing, axial osteosclerosis. She reported drinking 2 gallons of instant tea each day since 12 yr of age. Fluoxetine had been taken intermittently for 5 yr. Ion-selective electrode methodology quantitated F(-) in her blood, urine, fingernail and toenail clippings, tap water, and beverage. Radiographs showed marked uniform osteosclerosis involving the axial skeleton without calcification of the paraspinal, intraspinal, sacrotuberous, or iliolumbar ligaments. Minimal bone excrescences affected ligamentous attachments in her forearms and tibias. DXA Z-scores were +10.3 in the lumbar spine and +2.8 in the total hip. Her serum F(-) level was 120 microg/liter (reference range, 20-80 microg/liter), and a 24-h urine collection contained 18 mg F(-)/g creatinine (reference value, <3). Fingernail and toenail clippings showed 3.50 and 5.58 mg F(-)/kg (control means, 1.61 and 2.02, respectively; p(s) < 0.001). The instant tea beverage, prepared as usual extra strength using tap water with approximately 1.2 ppm F(-), contained 5.8 ppm F(-). Therefore, the tea powder contributed approximately 35 mg of the 44 mg daily F(-) exposure from her beverage. Fluoxetine provided at most 3.3 mg of F(-) daily. SF from habitual consumption of large volumes of extra strength instant tea calls for recognition and better understanding of a skeletal safety limit for this modern preparation of the world's most popular beverage.

Degenerative lumbar spondylolisthesis: Anatomy, biomechanics and risk factors

Degenerative spondylolisthesis (DS) is a major cause of spinal stenosis and is often related to low back and leg pain. We reviewed the anatomical and biomechanical predisposition of lumbar DS and discuss possible predictors and risk factors for this condition. Spinal segment L4-L5 is most vulnerable because of the great forces in this region and the increased mobility of this segment due to the specific anatomy of quadratus lumborum muscle and iliolumbar ligament. A high pelvic incidence and lumbar lordosis increase the forces on the low spinal segments and probably raise the risk for DS. Individuals with relatively more sagittal orientation of the lumbar facets have a higher probability of developing DS because such joints have less ability to resist the shearing forces. Disc degeneration is not an important predisposing factor for DS. Reduced disc space caused by disc degeneration increases the facet joint articulation overlap and together with osteophyte formation and ossification of spinal ligaments, can be seen as a part of the restabilization process. Deep abdominal and paraspinal muscles, most likely, play an important role in dynamic lumbar stability. Factors found to be associated with lumbar DS include age > 50, female gender, pregnancy, African American race, and generalized joint laxity.

Repositioning injuries of nerve root L5 after surgical treatment of high degree spondylolistheses and spondyloptosis--in vitro studies

Temporary or persistent paralysis of the fifth lumbar nerve root have been frequently reported as complications following reposition of high degree spondylolisthesis. According to an outcome analysis of sixty-four patients, we found an increased incidence of motor damages after reduction of Meyerding degree four anterolisthesis or spondyloptosis. There were no signs of intradural root compression or nerve injury tracable. In order to detect extraforaminal strictures, the anatomic course of the lumbosacral plexus and its relation to neighbouring structures, especially pelvivertebral connective tissue junctions were recorded in cadavric measurements. Beside an number of variations in origin and course of the iliolumbar ligament complex, we observed a junction between os sacrum and the anterior part of the fifth lumbar vertebrae in 14/30 specimen, constantly running anterior to the fifth lumbar nerve root. In addition the nerve was fixed to the sacral periostium a few centimeters distal this crossing in about 20% of all cases. Pathophysiological effects were measured in reposition trials, using a continuous pressure monitoring system. A reposition of more than 20 mm resulted in a perineural pressure > 30 mmHg. This caused a nerve fiber deformation at the edge of the compressed nerve segment. Increased pressure leads to a nodular displacement of perineural fat as well as intraneural fascicles.

Identification and prediction of transitional vertebrae on imaging studies: Anatomical significance of paraspinal structures

The aim of our study was to examine the locational distribution of paraspinal structures on MRI and to determine any predictable parameters that may be used for the identification of transitional vertebra (TV). We enrolled 534 patients who underwent MRI of their lumbosacral spine. The locations of the paraspinal structures, such as aortic bifurcation (AB), IVC confluence (IC), right renal artery (RRA), celiac trunk (CT), SMA root (SR), and iliolumbar ligament (ILL), were determined using "cross link" in PACS. We also assessed the morphology of the TV. The MRI showed that the most common site of the paraspinal structures in the normal group was AB at the lower L4, IC at the L4-5 disc space, RRA at the L1-2 disc space, CT at the T12-L1 disc space, SR at the upper L1, and ILL at the L5. The frequency of TV was 23.8% (lumbarization, 9.9%; sacralization, 13.9%). The paraspinal structures of the S1 lumbarization were positioned more toward the caudal location, whereas the paraspinal structures of the L5 sacralization were positioned more toward the cephalic location (P < 0.01). In conclusion, AB, IC, RRA, CT, SR, and ILL are useful landmarks for predicting the presence of TV on MRI. TV is possible when these paraspinal structures are in positions outside of the frequent locations.

Poster 210: Fluoroscopically Guided Versus Blind Steroid Injections for Chronic Iliolumbar Syndrome: Case Control Study

Setting: Interventional pain clinic and fluoroscopy suite. Patients: All patients in the preceding year receiving injections of the iliolumbar ligament were included, in order to study differences in outcome in those receiving fluoroscopically guided injections. A total of 6 were identified retrospectively. 3 had “blind” injections and 3 had fluoroscopically guided injections. Case Descriptions: Each group consisted of 2 women and 1 man with back pain for 1 year or more, with matched preinjection average severity on verbal numeric rating scale (VNRS) score of 7.7.

Effects of slouching and muscle contraction on the strain of the iliolumbar ligament

The study consisted of biomechanical modelling and in vitro experiments. The objective of the study was to find a mechanical cause of acute low back pain (LBP) in everyday situations. The precise mechanism producing LBP is still under discussion. Most biomechanical studies link the concepts of stooped postures and buckling instability of the spine under high compressive load. No biomechanical model addresses situations with small or neglectable compressive spinal load. The proposed conceptual model describes strain on the iliolumbar ligaments (ILs) when slouching from standing upright. Delayed or absent recruitment of back muscles that protect against hyperkyphosis of the lumbar spine is a conditional factor. Erector spinae and multifidus muscle forces are included, representing a bifurcation in back muscle force: one part acting on the iliac bones and one part acting on the sacrum. The multifidus muscle action on the sacrum may produce nutation which can be counteracted by pelvic floor muscles, which would link back problems and pelvic floor problems. The effect of simulated muscle tension on the ILs and the L5-S1 intervertebral disc angle was measured using embalmed specimens. Forces were applied to simulate erector spinae and sacral part of multifidus tension, bilateral up to 100 N each. Strain gauge sensors registered elongation of the ILs. Explorative biomechanical model calculations show that dynamic slouching, driven by upper body weight and (as an example) rectus abdominis muscle force may produce failure load of the spinal column and the ILs. The quasi-static test on embalmed specimens showed a significant increase of IL elongation with simulated rectus abdominis muscle force. Adding erector spinae or multifidus muscle tension eased the ILs. Sudden slouching of the upright trunk may create failure risk for the spine and ILs. This loading mode may be prevented by controlling loss of lumbar lordosis with erector spinae and multifidus muscle force.

The Inverted Napoleon's Hat Sign

Spondylolisthesis is the anterior displacement of one vertebra with respect to another and frequently occurs at the lumbosacral junction. The inverted Napoleon’s hat sign is produced when a severely subluxed L5 vertebral body (the dome of the hat) projects end-on and overlaps the sacrum, with the superimposition of images appearing as an inverted Napoleon hat (Fig 2). In the absence of a spondylolysis pars interarticularis defect or spondylolisthesis, the presence of a marked hyperlordosis at the lumbosacral junction may also simulate the appearance of the inverted Napoleon hat. The anterior slip of the L5 vertebra on S1 and the resulting L5-S1 kyphosis are counterbalanced by hyperlordosis of the lumbar spine and increased verticalization of the sacrum resulting from a compensatory hamstring contracture and uprighting of the pelvis around the hip joints (2). These factors contribute to deformities seen in spondylolisthesis and are accompanied by the potential over time to develop a pressure erosion of the anterior aspect of S1 and the posterior portion of the L5 vertebral body. In the standing position, the center of gravity normally passes through the lumbosacral joint, causing the vertebral column to slide anteriorly on the intervertebral disk at this level. The lumbosacral junction resists anterior dislocation because of the stabilization provided by the anterior longitudinal ligament, the posterior bands of the iliolumbar ligaments, and the articular facet joints (3). The facet joint anatomy normally helps prevent slippage on the anteroinferiorly directed sacral promontory at the lumbosacral junction by means of the inferior articular facets of L5, which are anteriorly oriented and engage the posteriorly directed S1 articular facets (3). An approximately 140° angle normally exists between L5 and the sacral axis, along with a 40° angle of the S1 body from the horizontal, thereby contributing to the large amount of force imposed onto the superior articular processes of S1 (3). Notable disruption of any of these stabilizing forces may result in depiction of the inverted Napoleon’s hat sign.

Vibration testing of a fresh-frozen human pelvis: The role of the pelvic ligaments

A biodynamic model of the human pelvis is being developed in the frame of a research project on low back pain. In order to validate such model, the dynamic behaviour of the human pelvis needs to be investigated. In this study, a human fresh-frozen specimen comprising the three bones of the pelvic girdle and its ligamentous system has been used to perform vibration testing. In such test the response of the system to vibrations is measured at various points on the structure for frequencies between 10 and 340 Hz. The vibration testing is performed a first time on the specimen with intact ligamentous system. The measurements are taken two more times after subsequent bilateral resection of both the sacrotuberous and the sacrospinous ligaments first, and the iliolumbar ligaments afterwards. A comparison between the system response obtained in the three configurations provides information on the role of the resected ligaments in the dynamics of the system, thus on their relevance in the model. Results indicate that the sacrospinous, the sacrotuberous and the iliolumbar ligaments do not play a role in the pelvis dynamics as measured in this study, and will therefore not be represented in the biodynamic model.

Numbering of Lumbosacral Transitional Vertebrae on MRI: Role of the Iliolumbar Ligaments

The objective of this study was to determine whether identification of the iliolumbar ligaments is of practical use for numbering lumbosacral transitional vertebrae (LSTV). Five hundred consecutive lumbar spine MRI studies were reviewed. A standard protocol of sagittal and axial T1-weighted and T2-weighted spin-echo sequences was used. The sagittal images were assessed for the presence of an LSTV, and axial images were assessed for the level of origin of the iliolumbar ligaments. Of the 500 patients, 433 (86.6%) had normal lumbosacral segmentation and 67 (13.4%) had a transitional lumbosacral junction. The iliolumbar ligament was identified at L5 in all patients with normal lumbosacral segmentation (n = 433), bilaterally in 432 and unilaterally in one. Using the identification of the iliolumbar ligaments as a marker of the L5 vertebral level, we numbered 46 of the 67 LSTV as L5 transitions and 21 as S1 transitions. The iliolumbar ligament is readily identifiable on axial lumbar spine MRI and always arises from L5. We suggest that its position can be used to confidently assign lumbar levels in patients with LSTV.

Back pain in chronic renal failure

Patient SK, a 40-yr-old female, resident of Bhagalpurvillage in Bihar, India, was operated for gallstones3 years previously. On pre-operative checkup, mildrenal dysfunction was detected. She was asymptomaticfor renal disease with serum creatinine of 159mmol/l(1.8mg/dl), bland urinary sediment and small echo-genic kidneys on ultrasound. She was puton conservative management for chronic renal failure(CRF) and was doing well till 1 year ago. Since thenshe developed back pain, which increased on walking.Pain was dull in character without any radiation. Therewere no systemic complaints. In the past month whenher pain increased substantially, causing discomfort inday-to-day activities. On investigation she was foundto have moderate renal failure with blood ureanitrogen (BUN) of 11.8mmol/l and serum creatinineof 309mmol/l (3.5mg/dl). Other labs showed serumcalcium of 2.4mmol/l, phosphorus 1.1mmol/l, alkalinephosphatase 243U/l, uric acid 381mmol/l and intactparathyroid hormone (iPTH) of 182.0pg/ml. X-raysof bilateral forearms, pelvis and spine were taken(Figures 1–3, respectively), which revealed generalizedincrease in bone density, degenerative changeswith osteophytes in lumber vertebra, calcification ofbilateral iliolumbar and sacrospinous ligaments andinterosseous membrane calcification in forearms.Definitive diagnosis was reached with estimation offluoride levels in blood and urine, which were0.291mg/l and 0.962mg/l (15.3 and 50.6mmol/l),respectively. Her drinking water source, ground waterfrom a tubewell, was found to contain 3.910mg/l(205.9mmol/l) of fluoride. She was diagnosed to havefluorosis with moderate CRF and was advised to usedomestic reverse-osmosis-treated water for cookingand drinking.Main sources of fluoride include food and water.About 50–70% of fluoride is excreted by the kidneys[1]. Individuals with kidney disease have decreasedability to excrete fluoride in urine and are at risk ofdeveloping fluorosis even at normal recommendedlimit of 0.7 to 1.2mg/l (37–63mmol/l) of fluoride indrinking water [2]. In fluorosis with normal renalfunction, urine fluoride rises above 0.5–4.48mg/l(26–236mmol/l) and may reach 1.5–13.0mg/l(79–685mmol/l) [3]. Serum fluoride rises to0.04–0.28mg/l (2.1–14.7mmol/l) in such patients [1].Fluoride is bone-seeking due to its high affinity forcalcium phosphate and therefore accumulates in bone.Radiological changes can be quite similar to changesof renal osteodystrophy, and therefore the diagnosismay be missed unless specifically investigated.

Functional aspects of cross-legged sitting with special attention to piriformis muscles and sacroiliac joints

Transversely oriented pelvic muscles such as the internal abdominal oblique, transversus abdominis, piriformis and pelvic floor muscles may contribute to sacroiliac joint stability by pressing the sacrum between the hipbones. Surface electromyographic measurements showed that leg crossing lowers the activity of the internal oblique abdominal muscle significantly. This suggests that leg crossing is a substitute for abdominal muscle activity. No previous studies addressed piriformis muscle and related pelvic structures in cross-legged sitting. Angles of pelvis and femur were measured in healthy subjects in standing, normal sitting and cross-legged sitting, and were used to simulate these postures on embalmed pelvises and measure piriformis muscle elongation. Deformations of pelvic ring and iliolumbar ligament caused by piriformis muscle force were measured on embalmed pelvises. Cross-legged sitting resulted in a relative elongation of the piriformis muscle of 11.7% compared to normal sitting and even 21.4% compared to standing. Application of piriformis muscle force resulted in inward deformation of the pelvic ring and compression of the sacroiliac joints and the dorsal side of the pubic symphysis. Cross-legged sitting is common. We believe that it contributes to sacroiliac joint stability. This study demonstrates the influence of the piriformis muscle on sacroiliac joint compression. The elongation of the piriformis muscle bilaterally by crossing the legs may be functional in the build-up of active or passive tension between sacrum and femur.

Intervertebral disc degeneration associated with lumbosacral transitional vertebrae

We studied 52 patients, each with a lumbosacral transitional vertebra. Using MRI we found that the lumbar discs immediately above the transitional vertebra were significantly more degenerative and those between the transitional vertebrae and the sacrum were significantly less degenerative compared with discs at other levels. We also performed an anatomical study using 70 cadavers. We found that the iliolumbar ligament at the level immediately above the transitional vertebra was thinner and weaker than it was in cadavers without a lumbosacral transitional vertebra. Instability of the vertebral segment above the transitional vertebra because of a weak iliolumbar ligament could lead to subsequent disc degeneration which may occur earlier than at other disc levels. Some stability between the transitional vertebra and the sacrum could be preserved by the formation of either an articulation or by bony union between the vertebra and the sacrum through its transverse process. This may protect the disc from further degeneration in the long term.

Provocative sacroiliac joint maneuvers and sacroiliac joint block are unreliable for diagnosing sacroiliac joint pain

Mapping studies of pain elicited by injections into the sacroiliac joints (SIJs) suggest that sacroiliac joint syndrome (SIJS) may manifest as low back pain, sciatica, or trochanteric pain. Neither patient-reported symptoms nor provocative SIJ maneuvers are sensitive or specific for SIJS when SIJ block is used as the diagnostic gold standard. This has led to increasing diagnostic use of SIJ block, a procedure in which an anesthetic is injected into the joint under arthrographic guidance. However, several arguments cast doubt on the validity of SIJ block as a diagnostic gold standard. Thus, the effects of two consecutive blocks are identical in only 60% of cases, and the anesthetic diffuses out of the joint in 61% of cases, often coming into contact with the sheaths of the adjacent nerve trunks or roots, including the lumbosacral trunk (which may contribute to pain in the groin or thigh) and the L5 and S1 nerve roots. These data partly explain the limited specificity of SIJ block for the diagnosis of SIJS and the discordance between the pain elicited by the arthrography injection and the response to the block. The limitations of provocative maneuvers and SIJ blocks may stem in part from a contribution of extraarticular ligaments to the genesis of pain believed to originate within the SIJs. These ligaments include the expansion of the iliolumbar ligaments, the dorsal and ventral sacroiliac ligaments, the sacrospinous ligaments, and the sacrotuberous ligaments (sacroiliac joint lato-sensu). They play a role in locking or in allowing motion of the SIJs. Glucocorticoids may diffuse better than anesthetics within these ligaments. Furthermore, joint fusion may result in ligament unloading.