The iliolumbar ligament: its influence on stability of the sacroiliac joint

Prevalence and Risk Factors of Degenerative Spondylolisthesis and Retrolisthesis in the Thoracolumbar and Lumbar Spine - An EOS Study Using Updated Radiographic Parameters

STUDY DESIGN

Single centre, cross-sectional study.

OBJECTIVES

The objective is to report the prevalence of spondylolisthesis and retrolisthesis, analyse both conditions in terms of the affected levels and severity, as well as identify their risk factors.

METHODS

A review of clinical data and radiographic images of consecutive spine patients seen in outpatient clinics over a 1-month period is performed. Images are obtained using the EOS® technology under standardised protocol, and radiographic measurements were performed by 2 independent, blinded spine surgeons. The prevalence of both conditions were shown and categorised based on the spinal level involvement and severity. Associated risk factors were identified.

RESULTS

A total of 256 subjects (46.1% males) with 2304 discs from T9/10 to L5/S1 were studied. Their mean age was 52.2(± 18.7) years. The overall prevalence of spondylolisthesis and retrolisthesis was 25.9% and 17.1% respectively. Spondylolisthesis occurs frequently at L4/5(16.3%), and retrolisthesis at L3/4(6.8%). Majority of the patients with spondylolisthesis had a Grade I slip (84.3%), while those with retrolisthesis had a Grade I slip. The presence of spondylolisthesis was found associated with increased age (P < .001), female gender (OR: 2.310; P = .005), predominantly sitting occupations (OR:2.421; P = .008), higher American Society of Anaesthesiology grades (P = .001), and lower limb radiculopathy (OR: 2.175; P = .007). Patients with spondylolisthesis had larger Pelvic Incidence (P < .001), Pelvic Tilt (P < .001) and Knee alignment angle (P = .011), but smaller Thoracolumbar junctional angle (P = .008), Spinocoxa angle (P = .007). Retrolisthesis was associated with a larger Thoracolumbar junctional angle (P =.039).

CONCLUSION

This is the first study that details the prevalence of spondylolisthesis and retrolisthesis simultaneously, using the EOS technology and updated sagittal radiographic parameters. It allows better understanding of both conditions, their mutual relationship, and associated clinical and radiographic risk factors.

Levels of 91 circulating inflammatory proteins and risk of lumbar spine and pelvic fractures and peripheral ligament injuries: a two-sample mendelian randomization study

OBJECTIVE

Lumbar spine and pelvic fractures(LPF) are combined with peripheral ligament injuries(PLI), frequently. It has been reported that the site of fracture injury is usually paralleled by the secretion of inflammatory proteins. This study aimed to investigate the causal relationship between 91 circulating inflammatory proteins and LPF and PLI by using a Two-sample Mendelian randomization (MR) analysis.

METHODS

Single nucleotide polymorphisms (SNPs) associated with 91 circulating inflammatory proteins, as exposures were selected from a large genome-wide association study (GWAS). The genetic variant data for LPF and PLI as outcomes from the FinnGen consortium. The inverse-variance-weighted (IVW) method was utilized as the main analysis for exposures and outcomes. In addition, the final results were reinforced by the methods of MR Egger, weighted median, simple mode, and weighted mode. The sensitivity analyses were used to validate the robustness of results and ensure the absence of heterogeneity and horizontal pleiotropy. MR-Steiger was used to assess whether the causal direction was correct to avoid reverse causality.

RESULTS

This study has shown that Beta-nerve growth factor(Beta-NGF) and Interferon gamma(IFN-gamma) are both involved in the occurrence of LPF and PLI, and they are reducing the risk of occurrence(OR:0.800, 95%CI: 0.650-0.983; OR:0.723, 95%CI:0.568-0.920 and OR:0.812, 95%CI:0.703-0.937; OR:0.828, 95%CI:0.700-0.980). Similarly, Axin-1 and Sulfotransferase 1A1 (SULT-1A1) were causally associated with LPF(OR:0.687, 95%CI:0.501-0.942 and OR:1.178,95%CI:1.010-1.373). Furthermore, Interleukin-4(IL-4), Macrophage inflammatory protein 1a(MIP-1a), and STAM binding protein(STAM-BP) were causally associated with PLI(OR:1.236, 95% CI: 1.058-1.443; OR:1.107, 95% CI: 1.008-1.214 and OR:0.759, 95% CI: 0.617-0.933). The influence of heterogeneity and horizontal pleiotropy were further excluded by sensitivity analysis.

CONCLUSION

This study provides new insights into the relationship between circulating inflammatory proteins and LPF and PLI, and may provide new clues for predicting this risk.

A Comprehensive Analysis of the Behavior of Pelvic Incidence After Different Posterior Spinal Procedures in Elderly Patients With Spinal Deformity

STUDY DESIGN

A retrospective case-control study.

OBJECTIVE

To evaluate the behavior of pelvic incidence (PI) after different posterior spinal procedures in elderly patients with adult spinal deformity (ASD), to determine the potential associated factors with the variability in PI after spinal surgery and to comprehensively analyze its mechanisms.

METHODS

Elderly patients underwent long fusion to sacrum with and without pelvic fixation were assigned to Group L+P and Group L-P, respectively. In Group L-P, those with severe sagittal deformity were selected as Group A. 20 elderly patients with severe sagittal deformity underwent short lumbar fusion were included as Group B. The following radiographic parameters were evaluated: thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), lumbar lordosis (LL), PI-LL, sagittal vertical axis (SVA), T1 pelvic angle (TPA), and pelvic parameters. PI changing more than 5° (△PI > 5°) was considered as substantially changed.

RESULTS

For the whole cohort and in Group L+P, PI were not substantially changed (△PI ≤ 5°) after surgery. Besides the severer sagittal malalignment in patients with △PI > 5° in Group L-P, relatively larger mean age, greater proportion of female and lower preoperative PI were found than those in patients with △PI ≤ 5°. 70.8% of patients had substantial increase of PI in Group A, while only 10% of patients had in Group B (P < 0.001).

CONCLUSION

PI behaves differently under different conditions in elderly ASD patients. Besides severe sagittal deformity, aging, female and low preoperative PI are also the potential risk factors of PI increasing after long fusion to sacrum.

Effects of manipulations of oblique pulling on the biomechanics of the sacroiliac joint: a cadaveric study

BACKGROUND

There are many reports on the treatment of sacroiliac joint dysfunction by manipulation of oblique pulling (MOP). However, the specific mechanism of MOP on the sacroiliac joint remains unclear. This study aimed to investigate the effect of MOP on the biomechanics of the sacroiliac joint and the effect of the anterior sacroiliac ligament on the stability of the sacroiliac joint.

METHODS

First, MOP-F1 (F: force) and MOP-F2 were applied to nine cadaveric pelvises. Then, segmental resection of the anterior sacroiliac ligament was performed. The range of motion of the sacroiliac joint was observed in all procedures.

RESULTS

Under MOP-F1 and F2, the average total angles were 0.84° ± 0.59° and 1.52° ± 0.83°, and the displacements were 0.61 ± 0.21 mm and 0.98 ± 0.39 mm, respectively. Compared with MOP-F1, MOP-F2 caused greater rotation angles and displacements of the sacroiliac joint (p = 0.00 and p = 0.01, respectively). In addition, the rotation angles and displacements of the sacroiliac joint significantly increased after complete resection of the anterior sacroiliac ligament (p = 0.01 and p = 0.02, respectively). The increase was mainly due to the transection of the upper part of the anterior sacroiliac ligament.

CONCLUSIONS

MOP-F2 caused greater rotation angles and displacements of the sacroiliac joint and was a more effective manipulation. The anterior sacroiliac ligament played an important role in maintaining the stability of the sacroiliac joint; the upper part of the anterior sacroiliac ligament contributed more to the stability of the joint than the lower part.

Deferent Anatomical Presentations of Iliolumbar Ligament: A Cadaveric Study

This work was carried out to describe the detailed gross anatomy of the iliolumbar ligaments in human cadavers and to shed more light on these disputes regarding the configuration and direction of these ligaments. Twenty partially dissected human formalin-preserved cadavers originating from North America and Europe were investigated in this study. Blunt dissection was made through the ventral and dorsal aspects of the pelvic area of the cadavers. According to the current study, the anterior and posterior portions of the iliolumbar ligament most frequently attached to the 5th lumbar vertebra’s transverse process (70% and 80%, respectively). The body of the 4th lumbar vertebra with the 5th lumbar vertebra’ transverse process was the attachment of the anterior part (30%). The attachment of the posterior part was the body of the 5th lumbar vertebra (20%). The anterior and posterior parts of the iliolumbar ligament were inserted into the anterior tip of the iliac crest. There is an obvious variation in the morphological appearance of the iliolumbar ligament distinguished in attachments, length, width, thickness, number of bands, and the presence of accessory bands in the anterior part of the ligament. In addition, a new attachment for the anterior band was revealed in one-third of the specimens (body of the 4th lumbar vertebra) which have not been described before. Also, in one-fifth of the specimens, there was a new attachment for the posterior band (body of the 5th lumbar vertebra).

Biomechanical analysis of sacroiliac joint motion following oblique-pulling manipulation with or without pubic symphysis injury

Background: Oblique-pulling manipulation has been widely applied in treating sacroiliac joint (SIJ) dysfunction. However, little is known about the biomechanical mechanism of the manipulation. This study aims to analyze the SIJ motion under oblique-pulling manipulation, in comparison with compression and traction loads.

Methods/Study Design: A total of six specimens of embalmed human pelvis cadavers were dissected to expose the SIJ and surrounding ligaments. Through a servo-hydraulic testing system, biomechanical tests were performed on the stable pelvis and the unstable pelvis with pubic symphysis injury (PSI). A three-dimensional (3D) photogrammetry system was employed to determine the separation and nutation in three tests: axial compression (test A), axial traction (test B), and oblique-pulling manipulation (test C).

Results: After applying the testing loads, the range of nutation was no more than 0.3° (without PSI) and 0.5°(with PSI), separately. Except for test B, a greater nutation was found with PSI (p < 0.05). Under both conditions, nutation following test A was significantly greater than that of other tests (p < 0.05). SIJ narrowed in test A and separated in tests B and C, where the range of motion did not exceed 0.1 mm (without PSI) or 0.3 mm (with PSI) separately. Under both conditions, the separation of SIJ in test C was not as apparent as the narrowness of SIJ in test A (p < 0.05). Compared to SIJ, a more significant increasing displacement was found at the site of the iliolumbar ligament (p < 0.05). Nevertheless, when the force was withdrawn in all tests, the range of nutation and separation of SIJ nearly decreased to the origin.

Conclusion: Pubic symphysis is essential to restrict SIJ motion, and the oblique-pulling manipulation could cause a weak nutation and separation of SIJ. However, the resulting SIJ motion might be neutralized by regular standing and weight-bearing load. Also, the effect on SIJ seems to disappear at the end of manipulation. Therefore, the stretching and loosening of surrounding ligaments need to be paid more attention to.

Ligaments stabilizing the sacrum and sacroiliac joint: a comprehensive review

The sacroiliac joint is a diarthrodial synovial joint in the pelvis. Anatomically, it is described as a symphysis, its synovial joint characteristics being limited to the distal cartilaginous portion on the iliac side. It is a continuous ligamentous stocking comprising interconnecting ligamentous structures and surrounding fascia. Its ligaments, the primary source of its stability, include the anterior, interosseous and dorsal sacroiliac, the iliolumbar, sacrotuberous, and sacrospinous. Structural reinforcement is also provided by neighboring fascia and muscles. Lower back pain is a common presentation of sacroiliac joint disease, the best-established treatments being corticosteroid injections, bipolar radiofrequency ablation, and sacroiliac joint fusion.

The impact of a sacroiliac joint belt on function and pain using the active straight leg raise in pregnancy-related pelvic girdle pain

INTRODUCTION

Pelvic girdle pain (PGP) is the most common musculoskeletal concern in pregnancy. The Active Straight Leg Raise (ASLR) test is diagnostic. Sacroiliac joint (SIJ) belts are included in multimodal therapy, but there is no established predictive measure to determine which pregnant women will benefit.

OBJECTIVE

To determine if the ASLR score is immediately reduced by SIJ belt application and whether PGP pain and function improves after 4 weeks of belt use.

DESIGN

Prospective observational cohort study.

SETTING

Academic medical center.

PARTICIPANTS

Pregnant women at least 18 years of age in the second or third trimester of pregnancy with posterior PGP and ASLR score of 2 to 10.

INTERVENTIONS

Four-week SIJ belt use.

MAIN OUTCOME MEASURES

ASLR, Numerical Rating Scale (NRS), Pelvic Girdle Questionnaire (PGQ), Perceived Global Impression of Improvement (PGII).

RESULTS

Sixty-three women enrolled. On multivariable analysis, immediate belted ASLR score was -2.70 points lower than the non-belted ASLR score (P < .001). Four weeks later there was significant improvement in the ASLR score with a belt (M_diff  = -0.99; P = .001) and without a belt (M_diff  = -1.94; P < .001); the decline was more precipitous for the non-belted response (M_diff  = -0.96; P = .02). Current NRS pain scores declined from baseline by approximately -0.94 points (P < .001). This decline did not depend on ASLR scores (interaction P = .43) or wearing a belt at the time of testing (interaction P = .51). Similar conclusions held for participants' usual NRS score and average PGQ score. After 4 weeks, 82% reported improvement based on the PGII.

CONCLUSIONS

SIJ belts are a safe, well-tolerated, and effective therapeutic option for pregnancy-related PGP. The ASLR score is immediately reduced following SIJ belt application but does not predict pain score 4 weeks later. SIJ belt leads to significant improvements in pain and function over time.

[Chronic pain syndrome in diseases of periarticular tissues]

The search for an effective method of treating diseases of the musculoskeletal system is a rather actual problem for a practicing physician nowadays in connection with the modern lifestyle of most people. A prolonged stay in the same position, as a rule, leads to overstrain of the capsule-joint complexes, and, as a consequence, to the development of degenerative changes in the joints and periarticular tissues. These changes can manifest themselves clinically in the form of a chronic or acute pain syndrome. One of the common diseases characterized by degenerative periarticular changes with a variety of clinical manifestations are periarthropathies. Periarthropathy or periarthrosis is still the subject of discussion by doctors of related specialties: neurologists, orthopedists, rheumatologists, etc. Pain in this case can be caused by the primary degenerative process in muscles and tendons in combination with their chronic microtraumatization, ischemia, and reactive inflammation. Periarthropathy can be considered as a «train» of any arthropathy, because pain always causes muscle spasm, a change in the motor stereotype, a limitation of motor activity in the joint, etc. In the absence of joint pathology, it should be considered as a primary disease. There is still no common understanding of this nosological unit, including pathogenesis, classification, diagnostic algorithms and therapy. Treatment is based on general recommendations: limiting the load on the damaged joint, massage (according to indications), exercise therapy, manual therapy, physiotherapy. Drug therapy includes intramuscular or intraarticular administration of glucocorticosteroids (GCS), non-steroidal anti-inflammatory drugs (NSAIDs) but these drugs have certain side-effects and contraindications. Treatment of peritropathy with chondroprotectors (chondrogard) is rapidly gaining momentum, as well as GCS and NSAIDs, they reduce pain and increase the functionality of the joints, but, unlike the latter, their safety profile is much higher. The authors summarize current findings on this issue.

Biomechanics of the Sacroiliac Joint: Anatomy, Function, Biomechanics, Sexual Dimorphism, and Causes of Pain

BACKGROUND

The sacroiliac joints (SIJs), the largest axial joints in the body, sit in between the sacrum and pelvic bones on either side. They connect the spine to the pelvis and thus facilitate load transfer from the lumbar spine to the lower extremities. The majority of low back pain (LBP) is perceived to originate from the lumbar spine; however, another likely source of LBP that is mostly overlooked is the SIJ. This study (Parts I and II) aims to evaluate the clinical and biomechanical literature to understand the anatomy, biomechanics, sexual dimorphism, and causes and mechanics of pain of the SIJ leading to conservative and surgical treatment options using instrumentation. Part II concludes with the mechanics of the devices used in minimal surgical procedures for the SIJ.

METHODS

A thorough review of the literature was performed to analyze studies related to normal SIJ mechanics, as well as the effects of sex and pain on SIJ mechanics.

RESULTS

A total of 65 studies were selected related to anatomy, biomechanical function of the SIJ, and structures that surround the joints. These studies discussed the effects of various parameters, gender, and existence of common physiological disorders on the biomechanics of the SIJ.

CONCLUSIONS

The SIJ lies between the sacrum and the ilium and connects the spine to the pelvic bones. The SIJ transfers large bending moments and compression loads to lower extremities. However, the joint does not have as much stability of its own against the shear loads but resists shear due the tight wedging of the sacrum between hip bones on either side and the band of ligaments spanning the sacrum and the hip bones. Due to these, sacrum does not exhibit much motion with respect to the ilium. The SIJ range of motion in flexion-extension is about 3°, followed by axial rotation (about 1.5°), and lateral bending (about 0.8°). The sacrum of the female pelvis is wider, more uneven, less curved, and more backward tilted, compared to the male sacrum. Moreover, women exhibit higher mobility, stresses/loads, and pelvis ligament strains compared to male SIJs. Sacroiliac pain can be due to, but not limited to, hypo- or hypermobility, extraneous compression or shearing forces, micro- or macro-fractures, soft tissue injury, inflammation, pregnancy, adjacent segment disease, leg length discrepancy, and prior lumbar fusion. These effects are well discussed in this review. This review leads to Part II, in which the literature on mechanics of the treatment options is reviewed and synthesized.

Pelvic orthosis effects on posterior pelvis kinematics An in-vitro biomechanical study

The sacroiliac joint (SIJ) is a well-known source of low back pain, with increasing interest for both conservative and surgical treatment. Alterations in pelvis kinematics are hypothesized as a contributor to SIJ pain and pelvic orthoses one treatment option, but their effects on the pelvis are poorly understood. Alterations in movement patterns induced by the application of pelvic orthoses were determined in five human cadaveric pelvises. Deformations were obtained from the lumbosacral transition and the bilateral SIJ, using digital image correlation and a customized routine to compute the movements within the pelvis. Significant alterations were found for the movements at the SIJ, in particular a vast increase in axial (x-axis) rotation, accompanied by increased inferior (y-) translation of the sacrum relative to the ilium. Movement patterns at the lumbosacral transition changed, causing increases in axial rotation and decreased inferior translation of L5 relative to S1. Using a physiologic mode of load application gives novel insights into the potential effects of pelvic orthoses. The results of these in-vitro experiments vary markedly from previous experiments with loading limited to two or less axes. Furthermore, the influence of pelvic orthoses on the lumbosacral transition warrants further investigation.

Effects of Cutting the Sacrospinous and Sacrotuberous Ligaments

The sacrospinous (SS) and sacrotuberous (ST) ligaments form a complex at the posterior pelvis, with an assumed role as functional stabilizers. Experimental and clinical research has yielded controversial results regarding their function, both proving and disproving their role as pelvic stabilizers. These findings have implications for strategies for treating pelvic injury and pain syndromes. The aim of the present simulation study was to assess the influence of altered ligament function on pelvis motion. A finite elements computer model was used. The two-leg stance was simulated, with the load of body weight applied via the fifth lumbar vertebra and both femora, allowing for nutation of the sacroiliac joint. The in-silico kinematics were validated with in-vitro experiments using the same scenario of load application following SS and ST transection in six human cadavers. Modeling of partial or complete ligament failure caused significant increases in pelvis motion. This effect was most pronounced if the SS and ST were affected with 164% and 182%, followed by the sacroiliac and iliolumbar ligaments with 123% and 147%, and the pubic ligaments with 113% and 119%, for partial and complete disruption, respectively. Simultaneous ligament transection multiplied the effects on pelvis motion by up to 490%. Unilateral ligament injury altered the motion at the pelvis contralaterally. The experiments presented here provide strong evidence for the stabilizing role of the SS and ST. A fortiori, the instability resulting from partial or complete SS and ST injury merits consideration in treatment strategies involving these ligaments as important stabilizers. Clin. Anat. 32:231-237, 2019. © 2018 Wiley Periodicals, Inc.

Effect of Sacroiliac Joint Mobilization on the Level of Soft Tissue Pain Threshold in Asymptomatic Women

OBJECTIVE

This study aimed to evaluate the effect of sacroiliac joint (SIJ) mobilization and/or self-mobilization on the level of soft tissue pain threshold in 21- to 23-year-old asymptomatic women (n = 20).

METHODS

The FPIX Wagner Algometer was applied to compute the pressure pain threshold (PPT) over the right and left side of the iliolumbar ligament and lumbar erector spinae (L3). Measurements were taken of the right SIJ before and after a randomized protocol of oscillating mobilization, self-mobilization, and placebo treatment.

RESULTS

A main effect of intervention (mobilization, self-mobilization, placebo) was confirmed by analysis of variance, with increases in PPT over the iliolumbar ligament (F = 13.04, P < .05) and erector spinae (F = 12.28, P < .05) on the mobilized side. The Wilcoxon test indicated that SIJ mobilization increased PPT over the iliolumbar ligament (P < .05) and erector spinae (P < .05) on both sides. Self-mobilization increased erector spinae PPT on the exercised side (P < .05), whereas the placebo did not cause any changes in PPT (P > .05).

CONCLUSION

The study provides evidence of local and global pain modulation resulting from oscillatory mobilization of the SIJ in women without pain symptoms. Self-mobilization of the SIJ has limited analgesic application.

Effect of lumbar stabilization exercise on disc herniation index, sacral angle, and functional improvement in patients with lumbar disc herniation

[Purpose] This study aimed to examine the effects of pelvic movements on the back function of patients with lumbar disc herniation when lumbar stabilization exercise was applied to the patients, suggest an intervention method that can be used in future clinical therapies. [Subjects and Methods] Thirty patients with lumbar disc herniation underwent the intervention 30 minutes per day, three times per week for 4 weeks. Of them, 15 patients were assigned to the balance center stabilization resistance exercise group (experimental group I) and the other 15 were assigned to the three-dimensional stabilization exercise group (experimental group II). Before the intervention, disc herniation index was measured using magnetic resonance imaging, sacral angle was measured using X-ray, and back function was measured using the KODI. Four weeks later, these three factors were re-measured and analyzed. [Results] There was a significant pre- versus post-intervention difference in disc herniation index, sacral angle, and KODI in experimental group I and a significant difference in disc herniation index and KODI in experimental group II, and each group of disc herniation index and sacral angle had a significant difference. In experimental group I, each disc herniation index and sacral angle had a negative correlation. [Conclusion] The lumbar stabilization exercise, which controls balance using pelvic movements, improves mobility and stability of the sacroiliac joint; therefore, it increases pelvic and back movements. These kinds of movements not only improved proprioception sense, they also had positive effects on lumbar disc function recovery.

Pelvic ring injuries

Pelvic ring injuries exhibit a wide spectrum of severity; at times devastating with potentially serious immediate and long-term consequences. The anatomical and mechanistic basis of the injured pelvis is described. The non-operative and surgical management of pelvic ring disruption in the acute and definitive care settings is discussed. As emphasized here, basic principles, the mechanism of injury and pattern of instability help guide management.

Malalignment Syndrome in Runners

More than 80% of runners are out of alignment. The standard back examination should include assessment of pelvic alignment. An awareness of pelvic malalignment and the the malalignment syndrome is essential to allow one to provide proper care of a runner. The 3 most common presentations usually respond to a supervised, progressive treatment program. The validity of any research into the biomechanics of running should be questioned if the study has failed to look at whether pelvic malalignment was present and whether the altered, asymmetrical biomechanical changes attributable to the malalignment itself could have affected the results of the study.

The influence of simulated transversus abdominis muscle force on sacroiliac joint flexibility during asymmetric moment application to the pelvis

BACKGROUND

The role of so-called local muscle system in motor control of the lower back and pelvis is a subject of ongoing debate. Prevailing beliefs in stabilizing function of this system were recently challenged. This study investigated the impact of in vitro simulated force of transversely oriented fibres of the transversus abdominis muscle (a part of the local system) on flexibility of the sacroiliac joint during asymmetric moment application to the pelvis.

METHODS

In 8 embalmed specimens an incremental moment was applied in the sagittal plane to one innominate with respect to the fixed contralateral innominate. Ranges of motion of the sacroiliac joint were recorded using the Vicon Motion Capture System. Load-deformation curves were plotted and flexibility of the sacroiliac joint was calculated separately for anterior and posterior rotations of the innominate, with and without simulated muscle force.

FINDINGS

Flexibility of the sacroiliac joint was significantly bigger during anterior rotation of the innominate, as compared to posterior rotation (Anova P<0.05). After application of simulated force of transversus abdominis, flexibility of the joint did not change both during anterior and posterior rotations of the innominate.

INTERPRETATION

A lack of a stiffening effect of simulated transversus abdominis force on the sacroiliac joint was demonstrated. Earlier hypotheses suggesting a stiffening influence of this muscle on the pelvis cannot be confirmed. Consistent with previous findings smaller flexibility of the joint recorded during posterior rotation of the innominate may be of clinical importance for physio- and manual therapists. However, major limitations of the study should be acknowledged: in vitro conditions and simulation of only solitary muscle force.

Can hip abduction and external rotation discriminate sacroiliac joint pain?

AIM

The primary aim of the study is to determine if Hip Abduction and External Rotation (HABER) test is capable of reproducing familiar pain in individuals with low back pain (LBP) of sacroiliac joint (SIJ) origin (SIJ-positive) when compared with LBP of Non-SIJ origin (SIJ-negative). If so, the secondary aim is to determine the diagnostic accuracy of HABER test against the reference standard of pain provocation tests, and to determine which increments of the HABER test has highest sensitivity and specificity for identifying SIJ-positive individuals.

DESIGN

Single-blinded diagnostic accuracy study.

METHOD

Participants [n(122)] between ages of 18-50 y, suffering from chronic non-specific LBP (≥3 months) volunteered in the study. An experienced musculoskeletal physiotherapist evaluated and classified participants into either SIJ-positive [n(45)] or SIJ-negative [n(77)], based on reference standard of pain provocation tests [≥3 positive tests = SIJ-positive]. Another musculoskeletal physiotherapist, blinded to clinical groups, evaluated participants for reproduction of familiar pain during each increment (10°, 20°, 30°, 40°, and 50°) of HABER test.

RESULTS

The HABER test reproduced familiar pain in SIJ-positive individuals when compared with SIJ-negative individuals [p (0.001), R(2) (0.38), Exp(β) (5.95-10.32)], and demonstrated moderate level of sensitivity (67%-78%) and specificity (71%-72%) for identifying SIJ-positive individuals. Receiver operator curve analysis demonstrated that the HABER increments of ≥30° have the highest sensitivity (83%-100%) and specificity (52%-64%).

CONCLUSIONS

The HABER test is capable of reproducing familiar pain in SIJ-positive LBP individuals and has moderate levels of sensitivity and specificity for identifying SIJ-positive LBP individuals.

A comprehensive review of the sub-axial ligaments of the vertebral column: part I anatomy and function

BACKGROUND

As important as the vertebral ligaments are in maintaining the integrity of the spinal column and protecting the contents of the spinal canal, a single detailed review of their anatomy and function is missing in the literature.

METHODS

A literature search using online search engines was conducted.

RESULTS

Single comprehensive reviews of the spinal ligaments are not found in the extant medical literature.

CONCLUSIONS

This review will be useful to those who treat patients with pathology of the spine or who interpret imaging or investigate the anatomy of the ligaments of the vertebral column.

The molecular composition of the extracellular matrix of the human iliolumbar ligament

BACKGROUND CONTEXT

The human iliolumbar ligament connects the transverse process of L5 to the iliac crest and contributes to lumbosacral stability and has been associated with low back pain. However, different opinions exist regarding the functional relevance of the ligament.

PURPOSE

In the present study, we analyze the regional molecular composition of the ligament extracellular matrix.

STUDY DESIGN

Special attention is given to the attachment sites, to determine whether the ligament is subjected to a certain mechanical environment.

METHODS

Iliolumbar ligament samples, extending from one enthesis to the other, were removed from 11 cadavers and fixed in methanol. Cryosections were immunolabeled with a panel of antibodies directed against collagens, glycosaminoglycans, proteoglycans, matrix proteins, and neurofilament.

RESULTS

The mid-substance of the ligament labeled for all the molecules normally found in dense fibrous connective tissue including types I, III, and VI collagen, versican, dermatan -, chondroitin 4 -, and keratan sulfate. However, both entheses were fibrocartilaginous and labeled for type II collagen, aggrecan, and chondroitin 6- sulfate. A common feature was fat between the fiber bundles near the entheses. Occasionally this fat contained nerve fibers.

CONCLUSIONS

The existence of fibrocartilaginous entheses suggests that the insertion sites of the ligament are subject to both tensile and compressive loading-probably because of insertional angle changes between ligament and bone during loading. Our findings support the suggestion that the iliolumbar ligament might play an important role in the stabilization of the lumbosacral junction.

The role of ultrasound in diagnosis of the causes of low back pain: a review of the literature

Context:

Low back pain (LBP) is among the most prevalent musculoskeletal conditions in the developed countries. It is a common problem causing disability and imposing a huge economic burden to individuals and state organizations. Imaging plays an important role in diagnosis of the etiology of LBP.

Evidence Acquisition:

The electronic databases included: PubMed (1950 to present), Ovid SP Medline (1950 to present) and ISI (1982 to present) and Google Scholar. In every search engine another search was performed using various permutations of the following keywords: ultrasonography, ultrasound imaging, low back pain, back muscles, paraspinal muscles, multifidus, transverse abdominis, muscle size, spinal canal, sacroiliac joint and spondylolisthesis.

Results:

Magnetic resonance imaging (MRI) is widely used in evaluation of patients with LBP; however, high costs, limited availability and contraindications for its use have restricted MRI utilization. In a quest for a less expensive and readily available tool to investigate LBP, clinicians and researchers found ultrasonography (US) as an alternative. In this review we discuss the US application in diagnosis of some common causes of non-specific chronic LBP. Discussed topics include evaluation of spinal canal diameter, paraspinal and transabdominal muscles, sacroiliac joint laxity, pregnancy related LBP, sacroiliitis, and spondylolisthesis using US in patients with LBP.

Conclusions:

While the first researches on employing ultrasound in diagnosis of patients with LBP had been focused on spinal canal diameter, recent studies have been mostly performed to evaluate the role of transabdominal and paraspinal muscles on core stability and thereby LBP occurrence. On the other side, Doppler ultrasonography has recently played an important role in objective measurement of joint laxity as a common etiology for LBP. Doppler imaging also in pregnant patients with LBP has been recommended as a safe and sensitive method. As conclusion, according to recent and most prestigious studies, focusing more on transabdominal muscle thickness can be considered as future approach in investigations.

Influence of flexible fixation for open book injury after pelvic trauma--a biomechanical study

BACKGROUND

Implant loosening is frequently detected after fixation of open book injuries. Though many authors do not see this as a complication, it is often the reason for hardware removal or reinstrumentation in the case of remaining instability. We hypothesized that the flexibility of the implant has an influence on loosening and thus on failure of the construct.

METHODS

We used 6 fresh-frozen pelvic specimens and tested them with our recently introduced test setup for two-leg alternate loading. We subjected them to a non-destructive quasi-static test in the intact condition followed by a non-destructive cyclic test under axial sinusoidal loading with progressive amplitude. Afterwards we simulated an open book injury and performed fixation with three different configurations of a modular fixation system (1-, 2- or 4-rod configuration) in randomized order. Subsequently, the specimens were subjected to 3 cyclic tests with the same loading protocol as previously defined. Finally, each construct was cyclically tested to failure keeping the final rod configuration.

FINDINGS

We detected significantly greater mobility after 1-rod-fixation and no significant differences after 2-rod or 4-rod-fixation compared to the intact symphysis condition. In the destructive test series the 4-rod-fixation failed first followed by the 1-rod-fixation. The 2-rod-fixation sustained almost 3 times as many load cycles prior to failure as the 4-rod-fixation, whereas the 1-rod-fixation sustained twice as many cycles as the 4-rod-fixation.

INTERPRETATION

In conclusion, flexible fixation of the ruptured pubic symphysis in human specimens shows superior behavior with respect to load bearing capacity and ability to withstand cyclic loading compared to stiff constructs.

Two-leg alternate loading model--a different approach to biomechanical investigations of fixation methods of the injured pelvic ring with focus on the pubic symphysis

The dorsal component of the pelvic ring is considered to be the most essential element for the stability of the pelvic ring. None of the current biomechanical set-ups include the effect of shear stresses by alternating loads that the pelvic ring has to withstand during walking. We hypothesize that a biomechanical test set-up with two-leg alternate loading will lead to stress imitation at the pubic symphysis that are more similar to existing strains than other test set-ups, and would, therefore, be more adequate for biomechanical testing of fixation methods. A new biomechanical two-leg standing test set-up with an alternate pelvic loading was constructed and was validated with six human pelvises from fresh frozen cadavers. Three-dimensional motion tracking was performed. The specimens were subjected to a non-destructive quasi-static test and a non-destructive cyclic test with progressive load amplitude from 170 N to 340 N over 1000 cycles. The initial rotational 'range of motion' and 'mean displacement' around the vertical axis for a pre-load of 170 N was about 0.3° and 0.2°, respectively, increasing by 0.1-0.2° at a load of 340 N. The rotation around the vertical axis and the translation along the frontal horizontal axis confirmed the stability of the pubic symphysis. The rate of ascend of displacements decreased, once the rotation reached 1° or the translation reached 1mm. The current biomechanical test set-up was compared with previous clinical findings, and the method was found valid for measuring inter-segmentary movements at the pubic symphysis.

Ligamentous influence in pelvic load distribution

BACKGROUND CONTEXT

The influence of the posterior pelvic ring ligaments on pelvic stability is poorly understood. Low back pain and sacroiliac joint (SIJ) pain are described being related to these ligaments. Computational approaches involving finite element (FE) modeling may aid to determine their influence. Previous FE models lacked in precise ligament geometries and material properties, which might have influence on the results.

PURPOSE AND STUDY DESIGN

The aim of this study is to investigate ligamentous influence in pelvic stability by means of FE using precise ligament material properties and morphometries.

METHODS

An FE model of the pelvis bones was created from computer tomography, including the pubic symphysis joint (PSJ) and the SIJ. Ligament data were used from 55 body donors: anterior (ASL), interosseous (ISL), and posterior (PSL) sacroiliac ligaments; iliolumbar (IL), inguinal (IN), pubic (PL), sacrospinous (SS), and sacrotuberous (ST) ligaments; and obturator membrane (OM). Stress-strain data were gained from iliotibial tract specimens. A vertical load of 600 N was applied. Pelvic motion related to altered ligament and cartilage stiffness was determined in a range of 50% to 200%. Ligament strain was investigated in the standing and sitting positions.

RESULTS

Tensile and compressive stresses were found at the SIJ and the PSJ. The center of sacral motion was at the level of the second sacral vertebra. At the acetabula and the PSJ, higher ligament and cartilage stiffnesses decrease pelvic motion in the following order: SIJ cartilage>ISL>ST+SS>IL+ASL+PSL. Similar effects were found for the sacrum (SIJ cartilage>ISL>IL+ASL+PSL) but increased ST+SS stiffnesses increased sacral motion. The influence of the IN, OM, and PL was less than 0.1%. Compared with standing, total ligament strain was reduced to 90%. Increased strains were found for the IL, ISL, and PSL.

CONCLUSIONS

Posterior pelvic ring cartilage and ligaments significantly contribute to pelvic stability. Their effects are region- and stiffness dependent. While sitting, load concentrations occur at the IL, ISL, and PSL, which goes in coherence with the clinical findings of these ligaments serving as generators of low back pain.

Pyomyositis of the iliacus muscle and pyogenic sacroiliitis after sacroiliac joint block -A case report-

Sacroiliac joint block can be performed for the diagnosis and treatment of sacroiliac joint dysfunction. Although sacroiliac joint block is a common procedure, complications have not been reported in detail. We report a case of iliacus pyomyositis and sacroiliac joint infection following a sacroiliac joint block. A 70-year-old female patient received sacroiliac joint blocks to relieve pelvic pain. The patient was admitted to the emergency room two days after the final sacroiliac joint block (SIJB) with the chief complaints of left pelvic pain corresponding to a visual analogue scale (VAS) score of 9 and fever. A pelvic MRI indicated a diagnosis of myositis. After 1 month of continuous antibiotic therapy, the patient's erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level remained elevated. A ⁶⁷Ga SPECT/CT was done. Abnormal uptake was seen at the left sacroiliac joint (SIJ), and septic sacroiliitis was suspected. The CRP normalized to 0.29 mg/dl and the ESR decreased to 60 mm/hr, and the patient had no fever after 57 days of antibiotic therapy. She was directed for follow up at an outpatient clinic.

Sacroiliac joint pain as an important element of psoriatic arthritis diagnosis

Psoriatic arthritis (PsA) is a chronic inflammatory disease characterized by the coexistence of arthritis with psoriasis of the skin and nails. The sacroiliac joints were observed in 34-78% of patients with psoriatic arthritis. Due to such a high prevalence of SIJ dysfunction, understanding pathophysiology of pain and the associated pain pattern becomes a very important aspect of PsA diagnosis. As far as the etiology of SI joint dysfunction is concerned, it has not been disambiguated yet. Among the main causative factors, injuries and strains of the structures surrounding the joint are noted. Joint pathology usually manifests itself by pain occurring within the area of the joint. The causes of pain may be divided into two categories: intra-articular and extra-articular. Pain caused by the SI joint may be nociceptive or neural in nature, whereas the pain pattern characteristic of the joint correlates with its innervation and is consistent with S2 dorsal rami.

Simulated transversus abdominis muscle force does not increase stiffness of the pubic symphysis and innominate bone: an in vitro study

BACKGROUND

The transversus abdominis muscle is thought to exert a stiffening effect on the sacroiliac joints. However, it is unknown whether this muscle is capable of increasing pubic symphysis and innominate bone stiffness during load exerted on the pelvis. The objective of this study is to investigate whether in vitro simulated force of transversely oriented fibres of the transversus abdominis increases stiffness of the pubic symphysis and innominate bone.

METHODS

In 15 embalmed specimens an incremental moment was applied in the sagittal plane to one innominate with respect to the fixated contralateral innominate. For pubic symphysis motion and innominate bone deformation load-deformation curves were plotted and slopes of adjusted linear regression lines were calculated. The slopes are considered to be a measure of pubic symphysis and innominate bone stiffness. Slopes were tested for significant differences before and after simulation of the transversus abdominis force.

FINDINGS

Stiffness of pubic symphysis and innominate bone does not change under influence of simulated force of the transversus abdominis. For pubic symphysis, the slope of the regression line hardly changes, from 0.0341mm/Nm (SD 0.0277) before transversus abdominis force simulation to 0.0342mm/Nm (SD 0.0273) during simulation. For innominate bone, the mean slope increases minimally, from 0.0368mm/Nm (SD 0.0369) to 0.0413mm/Nm (SD 0.0395), respectively.

INTERPRETATION

Simulation of the force of a single muscle - transversus abdominis - does not increase stiffness of the pubic symphysis and innominate bone. The hypothesized stiffening influence of the transversus abdominis on the pelvic ring was not confirmed in vitro.

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.

Pregnancy-related pelvic girdle pain and its relationship with relaxin levels during pregnancy: a systematic review

PURPOSE

The present systematic review assessed the level of evidence for the association between relaxin levels and pregnancy-related pelvic girdle pain (PPGP) during pregnancy.

METHODS

PRISMA guidelines were followed to conduct this systematic review. Electronic search was carried out using six different databases. Observational cohorts, cross-sectional or case-control studies focused on the association between relaxin levels and PPGP during pregnancy were included. Studies selection was conducted by two reviewers who screened firstly for titles, then for abstracts and finally for full articles. Risk of bias was assessed using the Newcastle-Ottawa scale and the quality of evidence by the guidelines proposed by the Cochrane back review group.

RESULTS

731 references were identified. Six articles met the inclusion criteria and were considered for this systematic review. The main reason for the studies exclusion was PPGP related to gynaecological reasons. Five studies were case-control and one study was a prospective cohort. Four studies were ranked as high while two were ranked as low quality. Among the high quality studies, three found no association between PPGP and relaxin levels.

CONCLUSIONS

Based on these findings, the level of evidence for the association between PPGP and relaxin levels was found to be low. PPGP assessment and controlling for risk factors were found to increase bias leaving uncertainty in interpretation of these findings and a need for further research.

A finite element analysis of sacroiliac joint ligaments in response to different loading conditions

STUDY DESIGN

A finite element analysis of the sacroiliac joint (SIJ) and its associated ligaments utilizing a three-dimensional model constructed from computed tomography scans.

OBJECTIVE

To characterize the sacroiliac ligament strains in response to flexion, extension, and axial rotation loads and quantify the changes in SIJ stress and angular displacement in response to changes in ligament stiffness.

SUMMARY OF BACKGROUND DATA

The SIJ may be a major contributor to low back pain in up to 13% to 30% of patients. States of ligament laxity are often associated with hypermobility and possibly pain of SIJ origin. The mechanism by which the SIJ generates pain is both controversial and poorly understood.

METHODS

A finite element model of the human pelvis, SIJs, and sacroiliac ligaments was constructed from computed tomography scans. Ligament stiffnesses were altered and the SIJ stresses were compared with the original case. For simulated flexion, extension, and axial rotation scenarios, sacroiliac ligament strains were characterized and compared.

RESULTS

Sacroiliac joint stress and angular motion increases as ligament stiffness decreases. Periarticular intraligamentous strains vary depending on the magnitude and direction of the applied loads. Maximum ligamentous strains occur at the interosseous sacroiliac ligament.

CONCLUSION

The sacroiliac ligaments function to constrain the SIJ and decrease stress across the SIJ for different load scenarios. Decreasing sacroiliac ligament stiffness leads to both increased joint motion and stress.

Description of the iliolumbar ligament for computer-assisted reconstruction

STUDY DESIGN

The iliolumbar ligament (IL) was examined using morphometric and virtual methods.

OBJECTIVES

A macroscopic study was performed to measure the anterior (AIL) and the posterior part of the IL (PIL).

SUMMARY OF BACKGROUND DATA

Though being a widely accepted cause of low back pain and lumbosacral instability, the IL is neglected in computer-based biomechanical studies due to the lack of morphometric information.

METHODS

Frozen sections prepared from 29 human subjects were measured and 7-tesla MR images made to distinguish the AIL and PIL. Cuboids were designated as geometric figures to both parts of the ligament, allowing computer-based calculations of length, surface, volume and angle of positional relationships.

RESULTS

Based on 7-tesla MR imaging, virtual reconstruction was conducted for one male pelvis, including the IL. While left- and right-side parameters varied at a statistically significant level, no gender-dependencies could be determined. Lengths of 30 and 25 mm were measured for the AIL and PIL, as well as heights of 17-19 mm, respectively, and a thickness of 4mm.

CONCLUSIONS

Correlations between the side-dependent parameters and the AIL and the PIL of the same side indicate close functional relationships. Additional dependencies suggest that the IL is capable of compensating age-related as well as bone-attributed alterations in lumbosacral morphology. The IL data and the visualised ligament structures contribute to determination of the influence of the IL in spinal and sacroiliac stability by means of computer-assisted biomechanics.

Immunohistochemical demonstration of nerve endings in iliolumbar ligament

STUDY DESIGN

Immunohistochemical study on fresh cadaver specimens.

OBJECTIVE

Assessment of mechanoreceptor and nociceptor levels and distribution in iliolumbar ligament.

SUMMARY AND BACKGROUND DATA

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Relation between subjective and objective scores on the active straight leg raising test

DESIGN

Cross sectional.

OBJECTIVE

To fill a gap in the validation of the active straight leg raising (ASLR) test concerning the relation between a patient's subjective score on the ASLR test and the objective measured force.

SUMMARY OF BACKGROUND DATA

The ASLR test is used to classify patients presenting with pain in the low back and/or pelvic girdle. Although its reliability and validity have been demonstrated, some details are still lacking.

METHODS

The ASLR test was performed by 21 parous women with various ASLR scores. Subjective weakness was scored by the patient both with and without a pelvic belt; moreover the isometric forces of leg raising were measured.

RESULTS

The correlation coefficients between the subjective ASLR score and objective measured force at 0 and 20 cm elevation were -0.58 (P < 0.01) and -0.52 (P < 0.05), respectively, at the left side; and -0.45 (P < 0.05) and -0.63 (P < 0.01), respectively, at the right side. When measured with a pelvic belt the correlations were, respectively, -0.51 and -0.48 at the left side, and -0.47 and -0.50 at the right side (all P < 0.05). After applying a pelvic belt the mean subjective ASLR score decreased with 0.38 point at the left side and 0.48 point at the right side (both P < 0.05). With the belt, the measured force at 0 cm elevation increased by 11.6% (P < 0.001) at the left side and by 8.6% (P < 0.05) at the right side; at 20 cm elevation the changes in measured force were negligible. No significant correlation was found between the subjective and the objective changes elicited by the pelvic belt.

CONCLUSION

The subjective scores on the ASLR test correlate well with the objective measured forces; this supports the reliability of the ASLR test. The subjective influence of a pelvic belt on the ASLR score could not be objectified.

In vitro assessment of movements of the sacroiliac joint in the horse

REASONS FOR PERFORMING STUDY

Sacroiliac joint (SIJ) disease is associated with poor hindlimb action, lameness and poor performance in horses. However, little is known about the biomechanics of this low-motion joint.

OBJECTIVES

To determine in vitro the capacities of movement of the SIJ in the sagittal plane, and to test the effect of a sacrosciatic and sacrotuberal desmotomy on its stabilisation.

METHODS

Six anatomical specimens underwent cycles of flexion-extension of the lumbosacral joint (LSJ) before and after desmotomy. Kinematic triads were linked rigidly to the sacrum, spinous process of vertebra L5 and iliac wing. Angles were measured using a joint coordinate system based on anatomical frames.

RESULTS

The LSJ underwent regular movements of flexion and extension (overall mean +/- s.d. range 23.4 +/- 1.6 degrees). The only recorded movement of the SIJ was a nutation during LSJ flexion (overall mean +/- s.d. 0.8 +/- 0.5 degrees). Desmotomy induced an increase of that nutation (overall mean +/- s.d. 1.7 +/- 0.2 degrees).

CONCLUSIONS AND POTENTIAL RELEVANCE

Movements of the SIJ were small and coupled only with the flexion of the LSJ. The ligaments surrounding the SIJ have a strong effect on the stabilisation of this joint. Due to the limited amount of movement, its biomechanical study in vivo seems to be difficult. Further in vitro studies would be useful to determine the role of each ligament, to better understand the clinical consequences of the tears frequently observed during necropsy.

Interrater reliability and diagnostic accuracy of pelvic girdle pain classification

OBJECTIVE

The purpose of this study was to measure the reliability of a classification system for pelvic girdle pain (PGP) and diagnostic accuracy of selected examination and clinical special findings for diagnosis of PGP.

METHODS

The design involved a prospective epidemiological study of pregnancy-related PGP. Consecutive subjects were recruited and classified using criteria defined by previous studies. Two clinicians examined the subjects and classified each patient into 1 of 5 classification groups. Clinical examination and clinical special tests were performed on the patients with PGP. Statistical analysis involved interobserver agreement using a kappa statistic and sensitivity and specificity values for the examination and clinical special testing.

RESULTS

Twenty-one subjects were included in the analyses. Aggregated percentage of agreement for the classification system was 84.6%. The Cohen kappa was 0.78 (CI, 0.64-0.92; P < .0001), which indicated substantial agreement during selection of the classification system. Most clinical examination and clinical special-test findings demonstrated low sensitivity and high specificity, whereas clusters of findings including the lunge, manual muscle testing of the hip (lower extremities), and passive range of motion of the hip demonstrated the strongest diagnostic value.

CONCLUSION

Selected tests and measures are moderately discriminatory in diagnosing PGP. A classification system for diagnosing PGP demonstrates strong agreement and may be useful for clinicians.

The active straight leg raising test (ASLR) in pregnant women: differences in muscle activity and force between patients and healthy subjects

Pregnancy-related low back and pelvic pain (PLBP) is a frequent complication of pregnancy. Although pathological mechanisms underlying PLBP are obscure, dysfunction of the sacroiliac joints (SI-joints) seems to play an important role. A cross-sectional study was performed on 24 pregnant women with and without PLBP. The objective was to determine muscle activation patterns of trunk and leg muscles during the active straight leg raising test (ASLR) and static hip flexion, and to determine maximal hip flexion force at 0 and 20 cm leg raise height. Moreover, the effort to raise the leg was scored. The measurements resulted in several significant differences between the patients and healthy controls; among others (a) patients scored subjectively more effort during ASLR, (b) at both 0 and 20 cm leg raise height patients had less hip flexion force, and (c) patients developed more muscle activity during ASLR. Since pregnant women with PLBP developed a higher muscle activity during ASLR with a significantly lower output at 0 and 20 cm than healthy pregnant women, it could be proposed that the ASLR demonstrates a disturbed load transfer across the SI-joints in this population.

Intensity mapping of pain referral areas in sacroiliac joint pain patients

OBJECTIVE

To identify differences in pain referral areas, using intensity maps, between responders and nonresponders to a double diagnostic sacroiliac joint injection with a short- and long-acting local anesthetic in patients with chronic low back pain.

METHODS

From a group of 140 consecutive patients with chronic low back pain, 60 patients who met clinical criteria were included in the study. Twenty-seven demonstrated a positive response to a double diagnostic fluoroscopically guided intra-articular sacroiliac joint block and were compared with 33 patients with a negative response. Each patient's preinjection pain diagram was used to determine areas of pain referral. The summation of these pain referral zones for both groups was used to construct intensity maps.

RESULTS

No major differences were observed between responders and nonresponders with regard to mean size and distribution of referral pain areas. Intensity maps, however, showed differences in pain referral at the buttock in the areas overlying the sacroiliac joint (100% of the responders vs 80% of the nonresponders) and the ischial tuberosity (10% of the responders vs 100% of the nonresponders).

CONCLUSIONS

Overall referred pain maps appeared not to be useful to discriminate patients with an identified sacroiliac joint pain from chronic low back pain patients with pain from other sources. Differences were only found using intensity maps. By implementing these data, it could be concluded that patients with sacroiliac joint pain are less likely to experience pain in both the 'Fortin' and 'tuber' areas. This knowledge can be used as additional selection criterion for putative sacroiliac joint patients, next to sacroiliac joint pain provocation tests.

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.

Low back pain, the stiffness of the sacroiliac joint: a new method using ultrasound

Abnormal biomechanical properties of the sacroiliac joints are believed to be related to low back and pelvic pain. Presently, physiotherapists judge the condition of the sacroiliac joints by function and provocation tests, and palpation. No objective measuring device is available. Research is ongoing to identify the biomechanical properties of the sacroiliac joints from the dynamic behaviour of the pelvic bones. A new concept based on ultrasound (US) for the measurement of bone vibration is under investigation. The objective of this study was to validate this concept on a physical model and to assess the applicability in vivo. A model consisting of a piezo shaker covered by a layer of US transmission gel (representing bone and soft tissue) has been used. A packet of US detection signals is directed onto the shaker and correlation-based processing is used to estimate the difference in time-of-flight of their echoes. These variations of time are used to compute the displacement of the shaker at each pulse reflection. To assess the validity of our US technique, we compared the obtained measurements with the readings of the built-in strain gauge sensor. The experimental procedure has been tested on a volunteer where low-frequency excitation was provided through the ilium and vibration detected on the sacrum and ilia. The results demonstrated that the correlation-based approach is capable of reproducing the piezo shaker displacements with high accuracy (+/- 7%). Vibration amplitudes from 0.25 microm to 3 microm could be measured. The US technique was able to detect bone vibration in vivo. In conclusion, the principle based on US waves can be used to develop a new measurement tool, instrumental in studying the relation between the biomechanical properties of the sacroiliac joints and low back pain.

Contribution of pelvic floor muscles to stiffness of the pelvic ring

STUDY DESIGN

A biomechanical study in embalmed specimens, on the relation between applied tension in the pelvic floor muscles, stiffness of the pelvic ring and generation of movement in the sacroiliac joints.

OBJECTIVE

To gain insight into the effect of tension in the pelvic floor muscles on stiffness of the pelvic ring. Background. According to a model on selfbracing pelvic floor muscles have the capacity to stiffen the sacroiliac joints. However, this capacity has not been demonstrated in vitro yet.

METHODS

In 18 embalmed specimens an incremental moment was applied to the sacroiliac joints to induce rotation of the innominate bones in the sagittal plane. After assessment of the relationship between rotation angle and moment, springs were applied to the pelvis to simulate tension in the pelvic floor muscles. During the simulated tension the measurements were repeated. Differences in stiffness before and after applying springs were tested for significance.

RESULTS

In females, simulated tension in the pelvic floor muscles stiffened the sacroiliac joints with 8.5% (P < 0.05). In males no significant changes occurred. In both sexes a backward rotation of the sacrum occurred due to simulated tension in the pelvic floor muscles (P < 0.05). The sacroiliac joints of female specimens were more mobile in comparison to male specimens (P < 0.05).

CONCLUSIONS

In females, pelvic floor muscles have the capacity to increase stiffness of the pelvic ring. In addition, these muscles can generate a backward rotation of the sacrum in both sexes.

RELEVANCE

The ability of pelvic floor muscles to increase stiffness of the pelvic ring is of importance in patients with impairment of pelvic stability, especially in pelvic pain patients. Increased activity of these pelvic floor muscles might compensate for loss of pelvic stability by stiffening the pelvic ring and restoring proper load transfer through the lumbopelvic region.