The sacroiliac joint: review of anatomy, mechanics, and function

Sacroiliac Joint Dysfunction in Endurance Runners Using Wearable Technology as a Clinical Monitoring Tool: Systematic Review

BACKGROUND

In recent years, researchers have delved into the relationship between the anatomy and biomechanics of sacroiliac joint (SIJ) pain and dysfunction in endurance runners to elucidate the connection between lower back pain and the SIJ. However, the majority of SIJ pain and dysfunction cases are diagnosed and managed through a traditional athlete-clinician arrangement, where the athlete must attend regular in-person clinical appointments with various allied health professionals. Wearable sensors (wearables) are increasingly serving as a clinical diagnostic tool to monitor an athlete's day-to-day activities remotely, thus eliminating the necessity for in-person appointments. Nevertheless, the extent to which wearables are used in a remote setting to manage SIJ dysfunction in endurance runners remains uncertain.

OBJECTIVE

This study aims to conduct a systematic review of the literature to enhance our understanding regarding the use of wearables in both in-person and remote settings for biomechanical-based rehabilitation in SIJ dysfunction among endurance runners. In addressing this issue, the overarching goal was to explore how wearables can contribute to the clinical diagnosis (before, during, and after) of SIJ dysfunction.

METHODS

Three online databases, including PubMed, Scopus, and Google Scholar, were searched using various combinations of keywords. Initially, a total of 4097 articles were identified. After removing duplicates and screening articles based on inclusion and exclusion criteria, 45 articles were analyzed. Subsequently, 21 articles were included in this study. The quality of the investigation was assessed using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) evidence-based minimum set of items for reporting in systematic reviews.

RESULTS

Among the 21 studies included in this review, more than half of the investigations were literature reviews focusing on wearable sensors in the diagnosis and treatment of SIJ pain, wearable movement sensors for rehabilitation, or a combination of both for SIJ gait analysis in an intelligent health care setting. As many as 4 (19%) studies were case reports, and only 1 study could be classified as fully experimental. One paper was classified as being at the "pre" stage of SIJ dysfunction, while 6 (29%) were identified as being at the "at" stage of classification. Significantly fewer studies attempted to capture or classify actual SIJ injuries, and no study directly addressed the injury recovery stage.

CONCLUSIONS

SIJ dysfunction remains underdiagnosed and undertreated in endurance runners. Moreover, there is a lack of clear diagnostic or treatment pathways using wearables remotely, despite the availability of validated technology. Further research of higher quality is recommended to investigate SIJ dysfunction in endurance runners and explore the use of wearables for rehabilitation in remote settings.

The effects of Core Stability Exercises and Mulligan's mobilization with movement techniques on sacroiliac joint dysfunction

Purpose

Sacroiliac joint dysfunction (SIJD), while being the primary contributor to low back pain, is still disregarded and treated as low back pain. Mulligan's Mobilization with Movement (MWM) Techniques and Core Stability Exercises (CSE) are often used to treat low back pain. There is not much evidence that it is effective in SIJD. To evaluate the effectiveness of CSE coupled with MWM (CSE + MWM) in the treatment of SIJD.

Methods

39 patients with SIJD were recruited and randomly divided into distinct groups as follows: control group (n = 13), CSE group (n = 13) and CSE + MWM group (n = 13). The Numerical Pain Rating Scale (NPRS), the Roland Morris Disability Questionnaire (RMDQ), the Range of Motion (ROM), the Pressure Pain Threshold (PPT) and the pelvic tilt angle asymmetry ratio in the sagittal plane (PTAR) were used to gauge the intervention's success both before (M0) and after (M1) it. All experimental data were statistically analyzed.

Results

The SIJ-related pain metric significantly decreased in both the CSE + MWM group and the CSE group between M0 and M1, as determined by the NPRS and RMDQ. Between M0 and M1, The CSE group's left axial rotation ROM and lumbar flexion ROM were significantly decreased. The CSE + MWM group's extension ROM and left lateral flexion ROM both significantly increased between M0 and M1. In the difference variable (M1-M0), the CSE + MWM group substantially outperformed control group in the left lateral flexion ROM and outperformed the CSE group in the left axial rotation ROM.

Conclusion

In individuals with SIJD, CSE + MWM is beneficial in lowering pain, disability, and function. Treatment with CSE and MWM approaches for SIJ appears to boost this efficacy.

The effects of topping-off instrumentation on biomechanics of sacroiliac joint after lumbosacral fusion

BACKGROUND

Lumbar/lumbosacral fusion supplemented with topping-off devices has been proposed with the aim of avoiding adjacent segment degeneration proximal to the fusion construct. However, it remains unclear how the biomechanics of the sacroiliac joint (SIJ) are altered after topping-off surgery. The objective of this study was to investigate the biomechanical effects of topping-off instrumentation on SIJ after lumbosacral fusion.

METHODS

The validated finite element model of an intact lumbar spine-pelvis segment was modified to simulate L5-S1 interbody fusion fixed with a pedicle screw system. An interspinous spacer, Device for Intervertebral Assisted Motion (DIAM), was used as a topping-off device and placed between interspinous processes of the L4 and L5 segments. Range of motion (ROM), von-Mises stress distribution, and ligament strain at SIJ were compared between fusion (without DIAM) and topping-off (fusion with DIAM) models under moments of four physiological motions.

RESULTS

ROM at the left and right SIJs in the topping-off model was higher by 26.9% and 27.5% in flexion, 16.8% and 16.1% in extension, 18.8% and 15.8% in lateral bending, and 3.7% and 7.4% in axial rotation, respectively, compared to those in the fusion model. The predicted stress and strain data showed that under all physiological loads, the topping-off model exhibited higher stress and ligament strain at the SIJs than the fusion model.

CONCLUSIONS

Motion, stress, and ligament strain at SIJ increase when supplementing lumbosacral fusion with topping-off devices, suggesting that topping-off surgery may be associated with higher risks of SIJ degeneration and pain than fusion alone.

Modified unilateral iliac screw fixation with partial reduction in the treatment of high-grade spondylolisthesis at L5/S1 in adult patients: introduction of key technique, report of clinical outcomes and analysis of spinopelvic parameters

BACKGROUND

Management of high-grade spondylolisthesis (HGS) remains challenging. Spinopelvic fixation such as iliac screw (IS) was developed to deal with HGS. However concerns regarding constructs prominence and increased infection-related revision surgery have complicated it's use. We aim to introduce the modified iliac screw (IS) technique in treating high-grade L5/S1 spondylolisthesis and it's clinical and radiological outcomes.

METHODS

Patients with L5/S1 HGS who underwent modified IS fixation were enrolled. Pre- and postsurgical upright full spine radiographs were obtained to analyze sagittal imbalance, spinopelvic parameters, pelvic incidence-lumbar lordosis mismatch (PI-LL), slip percentage, slip angle (SA), and lumbosacral angle (LSA). Visual analogue scale (VAS), Oswestry disability index (ODI) were evaluated pre- and postoperatively for clinical outcomes assessment. Estimated blood loss, operating time, perioperative complications and revision surgery were documented.

RESULTS

From Jan 2018 to March 2020, 32 patients (15 males) with mean age of 58.66 ± 7.77 years were included. The mean follow-up period was 49 months. The mean operation duration was 171.67 ± 36.66 min. At the last follow-up: (1) the VAS and ODI score were significantly improved (p < 0.05), (2) PI increased by an average of 4.3°, the slip percent, SA and LSA were significantly improved (p < 0.05), (3) four patients (16.7%) with global sagittal imbalance recovered a good sagittal alignment, PI-LL within ± 10° was observed in all patients. One patient experienced wound infection. One patient underwent a revision surgery due to pseudoarthrosis at L5/S1.

CONCLUSION

The modified IS technique is safe and effective in treating L5/S1 HGS. Sparing use of offset connector could reduce hardware prominence, leading to lower wound infection rate and less revision surgery. The long-term clinical affection of increased PI value is unknown.

Use of iliac screw associated with more correction of lumbar lordosis than S2-alar-iliac screw for adult spinal deformity

Background

To date, there is a paucity of reports clarifying the change of spinopelvic parameters in patients with adult spinal deformity (ASD) who underwent long segment spinal fusion using iliac screw (IS) and S2-alar-iliac screw (S2AI) fixation.

Methods

A retrospective review of consecutive patients who underwent deformity correction surgery for ASD between 2013 and 2017 was performed. Patients were divided into two groups based on whether IS or S2AI fixation was performed. All radiographic parameters were measured preoperatively, immediately postoperatively, and the last follow-up. Demographics, intraoperative and clinical data were analyzed between the two groups. Additionally, the cohort was subdivided according to the postoperative change in pelvic incidence (PI): subgroup (C) was defined as change in PI ≥5° and subgroup (NC) with change < 5°. In subgroup analyses, the 2 different types of postoperative change of PI were directly compared.

Results

A total of 142 patients met inclusion criteria: 111 who received IS and 31 received S2AI fixation. The IS group (65.6 ± 26°, 39.8 ± 13.8°) showed a significantly higher change in lumbar lordosis (LL) and upper lumbar lordosis (ULL) than the S2AI group (54.4 ± 17.9°, 30.3 ± 9.9°) (p < 0.05). In subgroup (C), PI significantly increased from 53° preoperatively to 59° postoperatively at least 50% of IS cohort, with a mean change of 5.8° (p < 0.05). The clinical outcomes at the last follow-up were significantly better in IS group than in S2AI group in terms of VAS scores for back and leg. The occurrence of sacroiliac joint pain and pelvic screw fracture were significantly greater in S2AI group than in IS group (25.8% vs 9%, p < 0.05) and (16.1% vs 3.6%, p < 0.05).

Conclusions

Compared with the S2AI technique, the IS technique usable larger cantilever force demonstrated more correction of lumbar lordosis, and possible increase in pelvic incidence. Further study is warranted to clarify the clinical impaction of these results.

Etiopathogenesis of sacroiliitis: implications for assessment and management

The sacroiliac joints connect the base of the sacrum to the ilium. When inflamed, they are suspected to cause low back pain. Inflammation of the sacroiliac joints is called sacroiliitis. The severity of the pain varies and depends on the degree of inflammation. Sacroiliitis is a hallmark of seronegative spondyloarthropathies. The presence or absence of chronic sacroiliitis is an important clue in the diagnosis of low back pain. This article aims to provide a concise overview of the anatomy, physiology, and molecular biology of sacroiliitis to aid clinicians in the assessment and management of sacroiliitis. For this narrative review, we evaluated articles in English published before August 2019 in PubMed. Then, we selected articles related to the painful manifestations of the sacroiliac joint. From the retrieved articles, we found that chronic sacroiliitis may be caused by various forms of spondyloarthritis, such as ankylosing spondyloarthritis. Sacroiliitis can also be associated with inflammatory bowel disease, Crohn’s disease, gout, tuberculosis, brucellosis, and osteoarthritis, indicating common underlying etiological factors. The pathophysiology of sacroiliitis is complex and may involve internal, environmental, immunological, and genetic factors. Finally, genetic factors may also play a central role in progression of the disease. Knowing the genetic pre-disposition for sacroiliitis can be useful for diagnosis and for formulating treatment regimens, and may lead to a substantial reduction in disease severity and duration and to improved patient performance.

The Five Diaphragms in Osteopathic Manipulative Medicine: Myofascial Relationships, Part 1

Working on the diaphragm muscle and the connected diaphragms is part of the respiratory-circulatory osteopathic model. The breath allows the free movement of body fluids and according to the concept of this model, the patient's health is preserved thanks to the cleaning of the tissues by means of the movement of the fluids (blood, lymph). The respiratory muscle has several systemic connections and multiple functions. The founder of osteopathic medicine emphasized the importance of the thoracic diaphragm and body health. The five diaphragms (tentorium cerebelli, tongue, thoracic outlet, thoracic diaphragm and pelvic floor) represent an important tool for the osteopath to evaluate and find a treatment strategy with the ultimate goal of patient well-being. The two articles highlight the most up-to-date scientific information on the myofascial continuum for the first time. Knowledge of myofascial connections is the basis for understanding the importance of the five diaphragms in osteopathic medicine. In this first part, the article reviews the systemic myofascial posterolateral relationships of the respiratory diaphragm; in the second I will deal with the myofascial anterolateral myofascial connections.

What do we know about the biomechanics of the sacroiliac joint and of sacropelvic fixation? A literature review

The purpose of this review is to summarize the general knowledge about the biomechanics of the sacroiliac joint and sacropelvic fixation techniques. Additionally, this study aims to support biomechanical investigations in defining experimental protocols as well as numerical modeling of the sacropelvic structures. The sacroiliac joint is characterized by a large variability of shape and ranges of motion among individuals. Although the ligament network and the anatomical features strongly limit the joint movements, sacroiliac displacements and rotations are not negligible. Currently available treatments for sacroiliac joint dysfunction include physical therapy, steroid injections, Radio-frequency ablation of specific neural structures, and open or minimally invasive SIJ fusion. In long posterior construct, the most common solutions are the iliac screws and the S2 alar - iliac screws, whereas for the joint fixation alone, mini - invasive alternative system can be used. Several studies reported the clinical outcomes of the different techniques and investigated the biomechanical stability of the relative construct, but the effect of sacropelvic fixation techniques on the joint flexibility and on the stress generated into the bone is still unknown. In our opinion, more biomechanical analyses on the behavior of the sacroiliac joint may be performed in order to better predict the risk of failure or instability of the joint.

Sacroiliac joint morphologic changes from infancy to adulthood

BACKGROUND CONTEXT

Report of sacroiliac morphology changes during growth is limited in the literature and the interest of such morphology and its consequence for surgery is increasing.

PURPOSE

Aims of this work are (1) to anatomically define the sacroiliac joint (SIJ), and (2) to assess the influence of growth on the sacroiliac morphology and the pelvic parameters.

STUDY DESIGN

Forty-nine young subjects from 6 months to 18 years old (y/o) and 20 adults aged from 18 to 50 y/o were selected from our institutional patient database.

METHODS

They underwent a computed tomography (CT) examination on a 128-MDCT (GE Healthcare Optima CT660). Transverse CT image datasets were reconstructed, anonymized, and segmented with ITK-SNAP. Landmarks and surfaces were selected and a SIJ orientation analysis was performed using costumed Python scripts.

RESULTS

The subjects were divided into four groups: infants (1.9±1 y/o), children (6.9±1.7 y/o), adolescents (13.7±1.8 y/o), and adults (27.3±5.6 y/o). Differences between SIJ orientation were found significant between young subject groups for synovial sacrum SIJ orientation (p<.001) and iliac total SIJ orientation (p=.036). Both orientations of younger subjects were found significantly different from the adult group (p<.035). SIJ synovial sacrum and iliac total orientations correlated significantly with age (p<.03). All orientations correlated with pelvic incidence (p<.04) except for synovial sacrum SIJ orientation (p=.2). No gender or symmetrical differences were found significant in any group.

CONCLUSIONS

Morphologic definition of the SIJ confirmed the independency of the gender during growth. Such results will be beneficial for the analysis and management of vertebral pathology.

Joint coordinate system for biomechanical analysis of the sacroiliac joint

Sacroiliac joint (SIJ) biomechanics have been described in both in vitro and in vivo studies. A standard for joint coordinate systems has been created by the International Society of Biomechanics for most of the joints in the human body. However, a standardized joint coordinate system for sacroiliac joint motion analysis is currently still lacking. This impedes the comparison across studies and hinders communication among scientists and clinicians. As SIJ motion is reported to be quite limited, a proper standardization and reproducibility of this procedure is essential for the interpretation of future biomechanical SIJ studies. This paper proposes a joint coordinate system for the analysis of sacroiliac joint motion, based on the procedure developed by Grood and Suntay, using semi-automated anatomical landmarks on 3D joint surfaces. This coordinate system offers high inter-rater reliability and aspires to a more intuitive representation of biomechanical data, as it is aligned with SIJ articular surfaces. This study aims to encourage further reflection and debate on biomechanical data representation, in order to facilitate interpretation of SIJ biomechanics and improve communication between researchers and clinicians. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Loss of Pelvic Incidence Correction After Long Fusion Using Iliac Screws for Adult Spinal Deformity: Cause and Effect on Clinical Outcome

STUDY DESIGN

Retrospective observational cohort study.

OBJECTIVE

To determine change in pelvic incidence (PI) and loss of correction after long fusion with iliac screws, the effect of iliac screw loosening, and global alignment according to postoperative PI.

SUMMARY OF BACKGROUND DATA

Posterior long fixation and fusion of the thoracic to the ilium is one of the most common surgical treatments for adult spinal deformity (ASD). Long fusion to the sacrum with iliac screws decreases the PI by 3.9° after surgery. PI decreases once by long fusion with iliac screws. However, if the iliac screw loosens, PI may cause correction loss and return to the preoperative PI.

METHODS

We retrospectively reviewed the cases of 69 consecutive patients with ASD. Their mean age (SD) was 70.5 (7.3) years, 12% were male. PI was evaluated preoperatively, early- and 1-year postoperatively. We compared change in PI with and without loosening of iliac screws, spinopelvic parameters according to 1-year-postoperative PI.

RESULTS

PI decreased significantly from 51.8° (9.3°) to 48.1° (9.5°) early postoperatively (P < 0.01). PI increased significantly from 48.1° (9.5°) to 49.6° (9.7°) within a year postoperatively (P < 0.01). Significant loss of PI correction (2.3°, P < 0.01) occurred within a year after surgery in patients with iliac screw loosening and was significantly different from the PI loss in those without screw loosening (53.9°, 48.2°, P = 0.03). Pelvic tilt, sacral slope, C7 sagittal vertical axis, global tilt, and T1 pelvic angle were significantly smaller in the group with PI <50° postoperatively at 1 year compared with the group with PI >50°.

CONCLUSION

Although PI decreases after long fusion surgery with iliac screws, significant correction loss appears within a year. Loosening of iliac screws may exacerbate this loss. Patients with PI <50° postoperatively were able to maintain better global alignment.

LEVEL OF EVIDENCE

3.

Surgical Outcomes of Long Fusion Using Dual Iliac Screws Bilaterally for Adult Spinal Deformities: The Effect on the Loosening Rate and Sacroiliac Joint Correction

Introduction

We recently demonstrated that pelvic incidence (PI) decreases after long fusion using iliac screws (ISs) and plays a role in good sagittal balance postoperatively. By contrast, the IS loosening rate may cause reversion, increasing the PI and causing loss of sagittal balance. The aim of this study was to determine the effect of the number of ISs inserted into the iliac bone for long fusion to correct adult spinal deformities (ASDs) on the frequency of IS loosening, postoperative PI, and surgical outcomes.

Methods

We included data from 70 consecutive patients. Cases in which two ISs were inserted bilaterally comprised the dual IS group (Group D), whereas cases in which one IS was inserted bilaterally comprised the single IS group (Group S).

Results

IS loosening was observed in four patients in Group D (9%) and 14 patients in Group S (61%). Both early and one-year postoperative PI were significantly smaller in Group D (P < 0.001). The sagittal vertical axis (SVA) one-year postoperatively was significantly smaller in Group D (P = 0.003).

Conclusions

The loosening rate of dual ISs was as low as about one-seventh that of single ISs. Using dual ISs, postoperative PI can be kept small, possibly resulting in a smaller SVA.

A systematic review of the morphology and function of the sacrotuberous ligament

The sacrotuberous ligament (STL) has been linked to conditions such as pelvic girdle pain and pudendal nerve entrapment, yet its contribution to pelvic stability is debated. The purpose of this review was to explore the current understanding of the STL and highlight any gaps in knowledge regarding its anatomy and function. A systematic search of the literature was conducted, focussing on the morphology and attachments of the STL, the relationship of the STL with surrounding structures, and its neurovascular supply and function. A total of 67 papers and four textbooks were obtained. The attachment sites of the STL are largely consistent; however, the extent of its connections with the long head of biceps femoris, gluteus maximus, piriformis, the posterior layer of the thoracolumbar fascia, and sacrospinous ligament are unclear. Morphometric parameters, such as mean STL length (6.4-9.4 cm), depth (0.3-0.4 cm), and width (1.8-3.5 cm, at its mid-point) are variable within and between studies, and little is known about potential side-, age-, or sex-related differences. The STL is pierced in several sites by the inferior and superior gluteal arteries, but information on its innervation pattern is sparse. Functionally, the STL may limit sacral nutation but it appears to have a limited contribution to pelvic stability. Some morphological aspects of the STL warrant further investigation, particularly its connections with surrounding structures, innervation pattern and function. Knowledge of the detailed anatomy and function of this ligament is important to better understanding its role in clinical conditions. Clin. Anat. 32:396-407, 2019. © 2018 Wiley Periodicals, Inc.

What's Old Is New Again: The Sacroiliac Joint as a Cause of Lateralizing Low Back Pain

It has not been easy to identify mechanical failure of the sacroiliac joint (SIJ) with traditional imaging. The integrated model of function (Lee and Vleeming, 1998) suggests that under normal circumstances, form and force closure combined contribute to sacral nutation and “locking” the SIJ for optimal load transfer. This model is supported by clinical evidence and scintigraphic findings that contribute to successful therapy in 80% of cases. Single-photon emission computed tomography and x-ray computed tomography (SPECT-CT), a hybrid device, was used in a study of 1200 patients (64% female and 36% male patients with an average age of 42 years; range, 15–78 years) with a clinical diagnosis of SIJ incompetence (pelvic girdle pain syndrome). Standard clinical testing and an alternate series of tests were used as a reference standard for imaging. Symptoms were present for a mean of 43 months. Imaging finding were of increased uptake in the upper SIJ (S1–S2), with extension into the dorsal interosseous ligament and measurable by count profile. Associated findings of tendon enthesopathy reflected altered biomechanics around the pelvis. Ipsilateral adductor enthesopathy was found in 70% and contralateral hamstring enthesopathy in 60% of patients. SPECT-CT criteria for the diagnosis of SIJ incompetence were developed and validated. SPECT-CT is a valid and reproducible technique for the diagnosis of SIJ incompetence with high concordance and specificity compared to the reference standards. Findings are supportive of the integrated model of SIJ function proposed by Lee and Vleeming.

A Review of Natural Joint Systems and Numerical Investigation of Bio-Inspired GFRP-to-Steel Joints

There are a great variety of joint types used in nature which can inspire engineering joints. In order to design such biomimetic joints, it is at first important to understand how biological joints work. A comprehensive literature review, considering natural joints from a mechanical point of view, was undertaken. This was used to develop a taxonomy based on the different methods/functions that nature successfully uses to attach dissimilar tissues. One of the key methods that nature uses to join dissimilar materials is a transitional zone of stiffness at the insertion site. This method was used to propose bio-inspired solutions with a transitional zone of stiffness at the joint site for several glass fibre reinforced plastic (GFRP) to steel adhesively bonded joint configurations. The transition zone was used to reduce the material stiffness mismatch of the joint parts. A numerical finite element model was used to identify the optimum variation in material stiffness that minimises potential failure of the joint. The best bio-inspired joints showed a 118% increase of joint strength compared to the standard joints.

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.

Metabolic disturbances identified by SPECT-CT in patients with a clinical diagnosis of sacroiliac joint incompetence

PURPOSE

To establish the sensitivity and specificity of cross-sectional scintigraphy [single photon emission computed tomography (SPECT)] combined with computed X-ray tomography (CT) in the detection of sacroiliac joint (SIJ) mechanical dysfunction and evaluate reproducibility of reporting.

METHODS

Patients with pelvic girdle pain either on the basis of peri-partum SIJ dysfunction or trauma were included. These patients were imaged with bone scintigraphy with hybrid imaging with SPECT/CT.

RESULTS

The study group comprised 100 patients (72 females, 28 males). Trauma accounted for 52% and the remainder were patients with peri-partum pain. Average age was 43 years and average length of history was >2 years. The major finding was increased uptake in the upper SIJ and posterior soft-tissues/ligaments. Hybrid imaging had a sensitivity of 95% and specificity of 99%. Positive predictive value was 99% and negative predictive value 94%. Power of the test was 1.0. Reproducibility of the test was good with kappa values of 0.85.

CONCLUSION

Hybrid imaging with SPECT/CT reproducibly demonstrates metabolic alterations around the SIJ in patients with SIJ dysfunction, which we have termed SIJ incompetence. The condition is more common than previously recognised and frequently occurs after trauma, which has not been reported previously.

Clinical incidence of sacroiliac joint arthritis and pain after sacropelvic fixation for spinal deformity

PURPOSE

Sacroiliac fixation using iliac screws for highly unstable lumbar spine has been reported with an improved fusion rate and clinical results. On the other hand, there is a potential for clinical problems related to iliac fixation, including late sacroiliac joint arthritis and pain.

MATERIALS AND METHODS

Twenty patients were evaluated. Degenerative scoliosis was diagnosed in 7 patients, failed back syndrome in 6 patients, destructive spondyloarthropathy in 4 patients, and Charcot spine in 3 patients. All patients underwent posterolateral fusion surgery incorporating lumbar, S1 and iliac screws. We evaluated the pain scores, bone union, and degeneration of sacroiliac joints by X-ray imaging and computed tomography before and 3 years after surgery. For evaluation of low back and buttock pain from sacroiliac joints 3 years after surgery, lidocaine was administered in order to examine pain relief thereafter.

RESULTS

Pain scores significantly improved after surgery. All patients showed bone union at final follow-up. Degeneration of sacroiliac joints was not seen in the 20 patients 3 years after surgery. Patients showed slight low back and buttock pain 3 years after surgery. However, not all patients showed relief of the low back and buttock pain after injection of lidocaine into the sacroiliac joint, indicating that their pain did not originate from sacroiliac joints.

CONCLUSION

The fusion rate and clinical results were excellent. Also, degeneration and pain from sacroiliac joints were not seen within 3 years after surgery. We recommend sacroiliac fixation using iliac screws for highly unstable lumbar spine.

Individualized multi-modal management of osteitis pubis in an Australian Rules footballer

OBJECTIVE

The purpose of this case report is to describe and discuss the successful management of osteitis pubis in a semi-elite Australian Rules football player through the utilization of an individualized multi-modal treatment approach provided by a chiropractor.

CLINICAL FEATURES

A 20-year-old male semi-elite Australian Rules football player presented to a chiropractic clinic with groin pain of eight months duration. A clinical diagnosis of osteitis pubis was made through synthesis of the patient history and physical examination.

INTERVENTION AND OUTCOME

Treatment consisted of high velocity low amplitude spinal manipulative therapy, mechanically assisted adjusting techniques utilizing a hand-held mechanical thrusting instrument and drop piece table, myofascial release and active release soft tissue techniques, proprioceptive neuromuscular facilitation stretching, and an individually designed rehabilitation program. Resolution of signs and symptoms occurred over four weeks. No recurrence of injury was reported over a six-month period.

CONCLUSIONS

This case suggests that the implementation of an individualized multi-modal management approach directed specifically toward an athlete's deficiencies and requirements, may lead to a more rapid recovery from osteitis pubis.

Bone biopsy of the parasymphyseal pubic bone region in athletes with chronic groin injury demonstrates new woven bone formation consistent with a diagnosis of pubic bone stress injury

BACKGROUND

There is little scientific evidence available regarding the pathologic basis for chronic groin injury in athletes, a known difficult clinical problem.

HYPOTHESIS

Histological analysis of the superior pubic ramus in athletes with diagnosed chronic groin injury may reveal the nature of the pathologic process.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Ten athletes with a diagnosis of chronic groin injury by clinical criteria (at least 6 weeks of pain) and magnetic resonance imaging criteria (unequivocal increase in T2 signal intensity) underwent bone biopsy of the superior pubic ramus. The biopsy site was located in the parasymphyseal region in the area of increased magnetic resonance image signal intensity. Histologic analysis of the specimens was then undertaken.

RESULTS

Evidence of new woven bone was seen in all biopsy specimens. Signs of old bony injury were seen in 8 of the 10 specimens. There was no evidence of inflammation or osteonecrosis.

CONCLUSION

Histologic analysis of bone biopsy specimens taken from the parasymphyseal pubic bone region with magnetic resonance imaging T2-weighted increased signal intensity of athletes diagnosed by clinical and magnetic resonance imaging criteria as having chronic groin injury demonstrates new woven bone formation. This is consistent with the athlete having a bone stress injury that may contribute significantly to athletic groin pain.

Sacroiliac joint fusion and the implications for manual therapy diagnosis and treatment

The present paper examines gender differences and changes in prevalence of ankylosed sacroiliac joint (SIJ) with age. SIJs of 287 patients (159 males and 128 females), aged 22-93 years, were examined for fusion, using 3-D CT images. Presence, side and location of the fusion along the joint borders were recorded. Fusion of the SIJ was found to be gender and age dependent; present in 27.7% of all males in contrast to only 3.0% in females (p<0.001). The phenomenon increased with age in the male population from 5.8% in the 20-39 age cohorts to 46.7% in the 80+ cohort. As mobilization and/or manipulation of a dysfunctional SIJ are common procedures used by manual therapists, the effect that aging has on SIJ mobility requires therapists to alter or change their method with advancing age.

Hip joint range of motion restriction precedes athletic chronic groin injury

Although a restricted hip range of motion has been previously associated with chronic groin injury the temporal course of this association remains unclear. Accordingly the purpose of this prospective cohort study was to report preliminary findings examining whether hip joint range of motion restriction is associated with subsequent onset of athletic chronic groin injury. End-range internal and external hip joint range of motion was determined in 29 elite Australian football players, without previous history of groin injury. The players were followed for two subsequent playing seasons for the development of chronic groin injury. Four athletes developed chronic groin injury defined as at least 6 weeks of groin pain and missing match playing time. In athletes that developed chronic groin injury a lower body weight (p=0.02) and reduced total hip joint range of motion (p=0.03) were found to be associated. This study suggests that hip stiffness is associated with later development of chronic groin injury and as such may be a risk factor for this condition. This work should be viewed as preliminary and caution is advised in applying the conclusion to clinical practice as the numbers in this study were small.

Innervation of the sacroiliac joint in rats by calcitonin gene-related peptide-immunoreactive nerve fibers and dorsal root ganglion neurons

The sacroiliac joint (SIJ) can be a source of low back pain. Calcitonin gene-related peptide (CGRP) has been reported to play a significant role in nociceptive processing. However, the occurrence of CGRP-immunoreactive (CGRP-ir) sensory nerve fibers in the SIJ has not been fully defined. The present study investigated CGRP-ir nerve fibers supplying the SIJ. CGRP-ir nerve fibers in the vicinity of the SIJ cartilage and CGRP-ir neurons in the bilateral dorsal root ganglia (DRG) were examined immunohistochemically by administering anti-CGRP antiserum to rats. The SIJ was decalcified and cut into sections, and the CGRP-ir fibers around the SIJ cartilage were counted under microscopy. In another group, fluoro-gold (F-G), a neural tracer, was injected into the SIJ from the dorsal or ventral side with dorsal or ventral denervation. The number of F-G-labeled CGRP-ir neurons was counted in individual DRG. CGRP-ir fibers were observed more frequently in the tissues adjacent to the cranial part of the SIJ surface. In the case of dorsal denervation (ventral nerve supply), the CGRP-ir neurons composed 18.2% of the F-G-labeled neurons. In the case of ventral denervation (dorsal nerve supply), the CGRP-ir neurons composed 40.9% of the F-G-labeled neurons. There was a statistically significant difference in the number of CGRP-ir neurons between the ventral and dorsal nerve supplies to the SIJ. The cranial part of the dorsal side could be the part most associated with pain in the SIJ.

Sacroiliac joint bridging: demographical and anatomical aspects

STUDY DESIGN

A descriptive study of the association between sacroiliac joint bridging (SIB) and age, gender, laterality, and ethnic origin in a normal skeletal population. The effectiveness of radiographs in identifying SIB was also evaluated.

OBJECTIVES

To characterize the phenomenon of SIB demographically and anatomically and to evaluate the validity of diagnosis based on roentgenograms.

SUMMARY AND BACKGROUND DATA

Although SIB is an important diagnostic parameter in many spinal diseases, the type of association between them has never been established. Furthermore, the extent of SIB in humans and its relationship to demographic parameters await osteological research as radiograph studies hamper the results.

METHODS

Two thousand eight hundred and forty-five skeleton pelves were examined for SIB. Extent and laterality were recorded. Ten pelves (5 with SIB and 5 without) were X-rayed and the roentgenograms given to radiologists for evaluation.

RESULTS

Sacroiliac bridging was present in 12.27% of all males, contrasted with only 1.83% of females (P < 0.001). SIB was independent of ethnic origin (P = 0.0535) but was age-dependent (r = 0.985; P = 0.0001). Bridging was present bilaterally in 38.6% of the individuals and in the superior region in 72.4%. Diffuse bridging (areas 1-6) was present in only 2.3% of the individuals. Radiologic examination was insensitive to diagnosis of SIB.

CONCLUSIONS

SIB is a common, but predominantly male phenomenon. Its occurrence is age-dependent and ethnicity independent. Bridging occurs mainly on the superior aspect of the sacroiliac joint. The irregular shape and orientation of sacroiliac joints preclude definitely distinguishing normal versus bridged joints from roentgenograms. Our findings also negate the belief that bridging/fusion of the sacroiliac joint represents the most severe form of osteoarthritis and mandate that they be separately recorded and that their significance be determined.

Facet blocks and sacroiliac joint injections

Facet and sacroiliac joint pathology are not an uncommon cause of back or neck pain. Imaging-guided techniques provide ready access to these synovial joints. Percutaneous injection of the facet or sacroiliac joints yields important diagnostic information as to whether or not the interrogated joint is involved in the patient's pain syndrome. The injection of a steroid-anesthetic mixture into these joints is capable of providing significant, albeit temporary, pain relief.

Fluoroscopically guided therapeutic sacroiliac joint injections for sacroiliac joint syndrome

OBJECTIVE

To investigate the outcomes resulting from the use of fluoroscopically guided therapeutic sacroiliac joint injections in patients with sacroiliac joint syndrome.

DESIGN

A retrospective study design with independent clinical review was utilized. Thirty-one patients were included; each patient met specific physical examination criteria and failed to improve clinically after at least 4 wk of physical therapy. Each patient demonstrated a positive response to a fluoroscopically guided diagnostic sacroiliac joint injection. Therapeutic sacroiliac joint injections were administered in conjunction with physical therapy. Outcome measures included Oswestry scores, Visual Analog Scale pain scores, work status, and medication usage.

RESULTS

Patients' symptom duration before diagnostic injection averaged 20.6 mo. An average of 2.1 therapeutic injections was administered. Follow-up data collection was obtained at an average of 94.4 wk. A significant reduction (P = 0.0014) in Oswestry disability score was observed at the time of follow-up. Visual Analog Scale pain scores were reduced (P < 0.0001) at the time of discharge and at follow-up. Work status was also significantly improved at the time of discharge (P = 0.0313) and at follow-up (P = 0.0010). A trend (P = 0.0645) toward less drug usage was observed.

CONCLUSIONS

These initial findings suggest that fluoroscopically guided therapeutic sacroiliac joint injections are a clinically effective intervention in the treatment of patients with sacroiliac joint syndrome. Controlled, prospective studies are necessary to further clarify the role of therapeutic injections in this patient population.

Origin and pathway of sensory nerve fibers to the ventral and dorsal sides of the sacroiliac joint in rats

The purpose of this study is to clarify sensory innervation in the ventral and dorsal sides of the sacroiliac joint. Fluoro-gold, a neural tracer, was injected into the left sacroiliac joint of adult rats from the dorsal side after denervation of the dorsal side, and the bilateral dorsal root ganglia (DRGs) from T13 to S4 were examined by fluorescence microscopy five days after injection. In another rat group, the DRGs were examined using the same methods after injection of fluoro-gold from the ventral side. In the case of dorsal denervation (ventral nerve supply), labeled neurons were mainly located in the ipsilateral DRGs from L1 to S2. On the other hand, in the case of ventral denervation (dorsal nerve supply), labeled neurons were noted in the ipsilateral DRGs from L4 to S2. The sacroiliac joint in rats is innervated differently on the ventral and dorsal sides: the sensory nerve fibers to the dorsal side of the sacroiliac joint were derived from the DRGs of lower lumbar and sacral levels (from L4 to S2); and those to the ventral side from the DRGs of upper lumbar, lower lumbar, and sacral levels (from L1 to S2).

Sensory innervation of the sacroiliac joint in rats

STUDY DESIGN

The segmental levels of dorsal root ganglions innervating the sacroiliac joint in rats were investigated using the retrograde transport method. The pathways and functions of the nerve fibers supplying the sacroiliac joint were determined by immunohistochemical detection of transported tracer.

OBJECTIVES

To study the sensory innervation of the sacroiliac joint and to elucidate the neural pathways of low back pain originating from the sacroiliac joint.

SUMMARY OF BACKGROUND DATA

The sacroiliac joint is a possible source of low back pain. The L4-S4 spinal nerves have been regarded as the nerves innervating the sacroiliac joint in humans. However, the origins of nerve fibers have not been analyzed experimentally with tracer methods.

METHODS

Cholera toxin B subunit, a neural tracer, was injected into the left sacroiliac joint of adult rats, and the bilateral dorsal root ganglions were immunohistochemically examined 4 days after injection. In another rat group, the dorsal root ganglions were examined using the same methods after resection of the left sympathetic trunk from L2 to the most caudal level. Thus, the pathways of the nerve fibers supplying the sacroiliac joint were investigated.

RESULTS

Labeled neurons were mainly located in the ipsilateral dorsal root ganglions from L1 to S2 of the unsympathectomized rats and in the ipsilateral dorsal root ganglions from L4 to S2 of the sympathectomized rats.

CONCLUSIONS

The sacroiliac joint was innervated by sensory neurons in dorsal root ganglions ipsilateral to the joint from L1 to S2. Sensory fibers from the L1 and L2 dorsal root ganglions passed through the paravertebral sympathetic trunk.

The Sacroiliac Joint as a Factor in Low Back Pain: A Review

Objectives:

To review the normal anatomy and biomechanics of the sacroiliac joint (SIJ) and the pathological changes that occur to them and to determine whether SIJ dysfunction is a factor in idiopathic low back pain.

Data Sources:

Articles containing information on the anatomy, biomechanics, and dysfunction of the SIJ. The databases searched were MEDLINE, the Cumulative Index to Nursing and Allied Health Literature, and SPORTDiscus.

Studies Used:

Those found using the search terms sacroiliac joint and injury and sacroiliac joint and athletes. Additional sources were gathered from the reference lists of these initial sources.

Data Exfraction:

Data found pertinent to understanding the anatomy, biomechanics, and pathophysiology of the SIJ region were used, as well as data on the existence and prevalence of SU dysfunction and its relation to low back pain.

Conclusions:

The literature provides strong evidence that SIJ dysfunction should be considered a major factor in the etiology of idiopathic low back pain.

Sacroiliac joint pain referral zones

OBJECTIVE

To determine the patterns of pain referral from the sacroiliac joint.

STUDY DESIGN

Retrospective.

PARTICIPANTS/METHODS

Fifty consecutive patients who satisfied clinical criteria and demonstrated a positive diagnostic response to a fluoroscopically guided sacroiliac joint injection were included. Each patient's preinjection pain description was used to determine areas of pain referral, and 18 potential pain-referral zones were established.

OUTCOME MEASURES

Observed areas of pain referral.

RESULTS

Eighteen men (36.0%) and 32 women (64.0%) were included with a mean age of 42.5 years (range, 20 to 75 yrs) and a mean symptom duration of 18.2 months (range, 1 to 72 mo). Forty-seven patients (94.0%) described buttock pain, and 36 patients (72.0%) described lower lumbar pain. Groin pain was described in 7 patients (14.0%). Twenty-five patients (50.0%) described associated lower-extremity pain. Fourteen patients (28.0%) described leg pain distal to the knee, and 6 patients (14.0%) reported foot pain. Eighteen patterns of pain referral were observed. A statistically significant relationship was identified between pain location and age, with younger patients more likely to describe pain distal to the knee.

CONCLUSIONS

Pain referral from the sacroiliac joint does not appear to be limited to the lumbar region and buttock. The variable patterns of pain referral observed may arise for several reasons, including the joint's complex innervation, sclerotomal pain referral, irritation of adjacent structures, and varying locations of injury with the sacroiliac joint.

Clinical tests of the sacroiliac joint. A systematic methodological review. Part 1: Reliability

In the literature concerning the sacroiliac joint (SIJ) there are numerous specific tests used to detect joint mobility or pain provocation. In this article the authors have reviewed 11 studies which investigated the reliability of these tests. The methodological quality of the studies was tested by a list of criteria developed by the authors. This list consisted of three categories: (1) study population, (2) test procedures and (3) test results. To each criterion a weighting was attached. The methodological score for nine out of the 11 studies was found to be acceptable. The results of this review, however, could not demonstrate reliable outcomes and therefore no evidence on which to base acceptance of mobility tests of the SIJ into daily clinical practice. There are no indications that 'upgrading' of methodological quality would have improved the final conclusions. With respect to pain provocation tests, the findings did not show the same trend. Two studies demonstrated reliable results using the Gaenslen test and the Thigh thrust test. One study showed acceptable reliability for five other pain provocation tests; however, since other authors have described contradictory results, there is a necessity for further research in this area with an emphasis on multiple test scores and pain provocation tests of the SIJ.

Sacroiliac dysfunction in construction workers

BACKGROUND

In the literature of manual medicine the sacroiliac joint is widely accepted as a potential source of low back pain. On the other hand, some investigations have detected sacroiliac joint dysfunction without concomitant low back pain. The prevalence of sacroiliac dysfunction in the population has been noted in the medical literature to be between 19.3% and 47.9%. However, the prevalence of sacroiliac dysfunction in the general population and for construction workers is unknown.

OBJECTIVE

This article presents results from the Hamburg Construction Workers Study in respect to sacroiliac diagnostics. The prevalence of and connection between sacroiliac dysfunction and low back pain are particularly interesting.

DESIGN AND PARTICIPANTS

The sacroiliac joint diagnostics were studied in a cross-section investigation of a cohort of 480 male construction workers. Manual examination is the standard in the diagnostics of sacroiliac joint conditions at present. The assessment of sacroiliac joint function by standing flexion test, the spine test, the iliac compression test, and the iliac springing test was operationalized as two categories: sacroiliac dysfunction I and II.

RESULTS

A prevalence of 29.0% was found for dysfunction I and 6.3% for dysfunction II, whereas a prevalence of 7.9% was found for the coprevalence of low back pain and sacroiliac dysfunction on the day of examination. This study demonstrated no statistical associations between low back pain and sacroiliac joint dysfunction.

CONCLUSIONS

The reason why symptomatic and asymptomatic sacroiliac dysfunctions exist has not yet been sufficiently explained. The identification of pain-provoking factors should be the aim of subsequent investigations. A further study with a prospective design will be necessary to answer the questions that remain.

Case report: can sacroiliac joint dysfunction cause chronic Achilles tendinitis?

This case study discusses the possible relationship between chronic Achilles tendinitis and sacroiliac joint dysfunction. The patient presented is an active pole jumper, competing at both the national and international levels. He suffered from chronic Achilles tendinitis during the 1994-95 season, and conservative treatment applied locally was not successful. The athlete discarded the possibility of operative debridement of the tendon. Instead, an evaluation of the kinetic chain of the lower extremity and pelvic-lumbar area was performed, and the athlete was diagnosed with sacroiliac joint dysfunction and Achilles tendinitis. Evaluation findings, treatment program, and treatment outcome are also presented. The literature regarding sacroiliac joint mechanics and biomechanics of the foot-knee-hip and pelvic area is discussed and used to support the author's thesis that sacroiliac joint dysfunction, in this case a backward rotation of the right ilium, may have changed the kinematic chain of the lower extremity and caused a tendinitis in the Achilles tendon of the affected leg. Sacroiliac joint function and dysfunction, the reliability of sacroiliac joint mobility tests, and the validity of treatment programs are still considered controversial, and more research is needed to understand these mechanisms.

Manipulation does not alter the position of the sacroiliac joint. A roentgen stereophotogrammetric analysis

STUDY DESIGN

A roentgen stereophotogrammetric analysis study of patients with sacroiliac joint dysfunction.

OBJECTIVES

To investigate whether manipulation can influence the position between the ilium and the sacrum, and whether positional tests for the sacroiliac joint are valid.

SUMMARY OF BACKGROUND DATA

Sacroiliac joint dysfunction is a subject of controversy. The validity of different sacroiliac joint tests is unknown. Long-standing therapeutic tradition is to manipulate supposed dysfunctions of the sacroiliac joint. Many manual therapists claim that their good clinical results are a consequence of a reduction of subluxation.

METHODS

Ten patients with symptoms and sacroiliac joint tests results indicating unilateral sacroiliac joint dysfunction were recruited. Twelve sacroiliac joint tests were chosen. The results of most of these tests were required to be positive before manipulation and normalized after manipulation. Roentgen stereophotogrammetric analysis was performed with the patient in the standing position, before and after treatment.

RESULTS

In none of the 10 patients did manipulation alter the position of the sacrum in relation to the ilium, defined by roentgen stereophotogrammetric analysis. Positional test results changed from positive before manipulation to normal after.

CONCLUSIONS

Manipulation of the sacroiliac joint normalized different types of clinical test results but was not accompanied by altered position of the sacroiliac joint, according to roentgen stereophotogrammetric analysis. Therefore, the positional test results were not valid. However, the current results neither disprove nor prove possible beneficial clinical effects achieved by manipulation of the sacroiliac joint. Because the supposed positive effects are not a result of a reduction of subluxation, further studies of the effects of manipulation should focus on the soft tissue response.

Sacroiliac motion for extreme hip positions. A fresh cadaver study

STUDY DESIGN

This study placed fresh cadavers in different hip positions and obtained sacroiliac kinematics. The magnitudes and directions of angular and linear sacroiliac motion are reported.

OBJECTIVES

To determine the three-dimensional motion at the left and right sacroiliac joints and to explore the mechanical structure of the sacroiliac joint.

SUMMARY OF BACKGROUND DATA

Previous in vivo and in vitro studies have reported various amounts of motion at the sacroiliac joints, ranging from no motion to 18 degrees. The results of previous studies have typically not been reported as data in classic engineering terms, and three-dimensional analyses are sparse. Importantly, previous studies have not used external hip positions to elucidate the full range of sacroiliac motion.

METHODS

Radiopaque markers were placed in the sacrum and each innominate bone before standardized performance of computed tomography scans at 3-mm intervals, with the fresh cadaver stabilized in the side-lying position on a specially constructed pallet. Computed tomography images were stored on magnetic tape, from which coordinates for centroids of the markers were obtained and subsequent mechanical analyses performed. The intersubchondral lines on the images were traced and reconstructed using computer technology to obtain the thickness of the intersubchondral joint space and the general configuration of the sacroiliac joints.

RESULTS

The methods used in this study were validated. The largest amount of sacroiliac motion occurred in the sagittal plane (7 degrees on left and 8 degrees on the right, with a range of 3 degrees to 17 degrees). Definite trends in the direction of angular sacroiliac motion occurred with respect to both bilateral and reciprocal hip joint positions. The translation or linear motion of the posterior superior iliac spines with respect to the sacrum ranged from 4 to 8 mm. This motion tended to occur in all directions, with no detectable trends. The average intersubchondral thickness of the sacroiliac joint was 1.2 mm and the shape of the joint resembled that of an airplane propeller.

CONCLUSIONS

Even though the subjects in this study were elderly, considerable angular and linear motion was in evidence. As such, it appears that extreme hip positions are necessary to elucidate full range of motion at the sacroiliac joint. The magnitude and direction of demonstrated sacroiliac motion appears to be sufficient to complement hip joint motion and influence motion at the lumbosacral junction and, thus, low back pain in both the direct and indirect sense.

Interinnominate motion and symmetry: comparison between gymnasts and nongymnasts

Some clinical approaches to the treatment of low back pain evaluate and treat observed asymmetries of pelvic posture and motion. Scientific evidence suggests the motion available between the innominate bones is small and variable in nature. The purposes of this investigation were 1) to determine if interinnominate motion of subjects without low back pain was symmetrical in reciprocal test posture combinations, 2) to assess innominate bone symmetry in standing, and 3) to determine if a difference in the magnitude of interinnominate motion was present between a subject group which performs more frequent flexibility activities compared with a subject group representing the general population. Thirty-four subjects (eight male gymnasts, nine female gymnasts, eight male nongymnasts, and nine female nongymnasts) were evaluated in standing and three other reciprocal postures (modified standing, modified sitting, and half-kneeling). In each posture, the Metrecom Skeletal Analysis System was used to obtain coordinates for the anterior and posterior iliac spines. Projection angles were used to determine the relative positions of the right and left innominate bones. Results suggest that stand to right modified standing and stand to left modified standing oblique sagittal interinnominate composite motions were symmetrical, stand to right modified sitting and stand to left modified sitting oblique sagittal interinnominate composite motions were asymmetrical, and stand to right half-kneel and stand to left half-kneel oblique sagittal interinnominate composite motions' symmetrical properties were mixed depending on the group. Gymnasts as a group were found to have asymmetrically positioned innominate bones while nongymnasts as a group had symmetrically positioned innominate bones.