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

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 Nevertheless, when the force was withdrawn in all tests, the range of nutation and separation of SIJ nearly decreased to the origin.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.

Relationship Between Sacroiliac Joint-related Pain and Spinopelvic Mobility

STUDY DESIGN

A case-control study.

OBJECTIVE

To evaluate the relationship between sacroiliac joint-related pain (SIJ-RP) and spinopelvic mobility.

SUMMARY OF BACKGROUND DATA

No specific radiological findings are available for the diagnosis of SIJ-RP. A previous study reported that a higher pelvic incidence and sacral slope (SS) values were significantly associated with sacroiliac joint pain. The concept of spinopelvic mobility, which is evaluated by the differences between SS in the standing and sitting positions, has been the focus of hip and spine surgeries in recent years.

MATERIALS AND METHODS

The SIJ-RP group comprised patients diagnosed with SIJ-RP based on physical findings and their response to analgesic injections. No other lumbar or hip joint diseases were observed. The non-SIJ-RP group comprised patients with lower back pain for reasons other than SIJ-RP. Radiographs of the lateral view of the pelvis in the standing and sitting positions were evaluated for all patients. We compared and analyzed the backgrounds, SS in the two positions, and difference in SS between the two positions in both groups.

RESULTS

In total, 245 patients were included in the study, with 49 and 196 patients in the SIJ-RP and non-SIJ-RP groups, respectively. More female patients experienced SIJ-RP than male patients ( P =0.0361). There were significant differences between the groups for SS in standing ( P =0.0076), sitting ( P =0.0005), and those with a difference between sitting and standing of <5° ( P =0.0278) in the univariate analyses. Logistic regression analyses, after adjustment for age and sex, revealed significant differences between the groups with an SS difference <5° ( P =0.0088; 95% confidence interval, 1.280-5.519), with an odds ratio of 2.7.

CONCLUSION

On evaluating spinopelvic mobility, we found that SIJ-RP was related to hypomobility of the sacrum, which could indicate the hypermobility of the sacroiliac joint.

Far-Contralateral Oblique (FCO) Sacroiliac Joint Injection: Description of a Novel Technique

Sacroiliac (SI) joint arthropathy is the primary pain generator in approximately 15–25% of patients with axial low back pain and traditionally diagnosed with >50% pain reduction following an intra-articular injection localized to the inferior 1/3 of the SI joint. The conventional technique for accessing the SI joint encompasses a posterior approach with fluoroscopic guidance at 10–20⁰ contralateral oblique angulation, and minor adjustments to this approach have been implemented with varying degrees of success. The authors present a novel technique for SI joint injection, infiltrating the middle third of the joint through an alternative far-contralateral oblique (FCO) approach, angulation between 20–40⁰. This approach theoretically endows easier access to the SI joint and at the very least provides another option for interventionalists in the diagnosis and treatment of sacroiliac joint pain. It can also be utilized to determine if a patient is a candidate for posterior percutaneous SI joint fusion. The authors sought to document this approach to ensure that it was both reproducible and safe, while recognizing the need for future studies.

Efficacy analysis of anterior debridement and bone graft fusion in the treatment of sacroiliac joint tuberculous arthritis: a retrospective analysis of 17 patients

Background

Sacroiliac joint tuberculous arthritis is a relatively rare site of tuberculosis infection, but it can lead to severe sacroiliac joint destruction and dysfunction. Since there are few studies on the surgical methods of sacroiliac joint tuberculosis (SJT), we adopted three different surgical methods based on different degrees of destruction of sacroiliac joint tuberculous arthritis. While revealing its clinical symptoms to improve the diagnostic accuracy, and to determine the safety and feasibility of this surgical approach in the treatment of sacroiliac joint tuberculous arthritis.

Methods

We retrospectively analyzed 17 patients with tuberculous arthritis of the sacroiliac joint treated by anterior debridement. All these patients underwent anterior debridement of tuberculosis with or without bone graft fusion. Mean postoperative follow-up was 17.2 months (12–25 months). The erythrocyte sedimentation rate (ESR) was used to judge the general situation after surgery, and the fusion of sacroiliac joints was observed by X-ray films and CT scans. And VAS and ODI were used to score to observe postoperative functional recovery.

Results

Anterior approach debridement is an effective surgical approach for sacroiliac joint tuberculous arthritis. All patients achieved effective relief of lower back and hip pain. The pain was significantly relieved 3 months after the operation, and the pain basically disappeared 6 months after the operation. The erythrocyte sedimentation rate was also significantly reduced after the operation, and it can basically return to the normal level 3 months after the operation. The VAS score and ODI index of the other 16 patients after surgery were significantly lower than those before surgery, except for 1 patient who died of severe type I respiratory failure and septic shock 3 months after surgery, The surviving patients were basically able to achieve stable fusion of the sacroiliac joint at 12 months postoperatively. None of the patients reported significant pain until the last follow-up visit.

Conclusions

The anterior approach is a very effective surgical method for the treatment of sacroiliac joint tuberculous arthritis, and it is safe and feasible. A clear operative field of view facilitates complete debridement and reduces recurrence, and its function recovers well with stable arthrodesis.

Minimally Invasive and Conservative Interventions for the Treatment of Sacroiliac Joint Pain: A Review of Recent Literature

Sacroiliac joint (SIJ) pain is responsible for approximately 15-25% of reported back pain. Patients with SIJ pain report some of the lowest quality of life scores of any chronic disease. Understanding of the physiology and pathology of the SI joint has changed dramatically over the years, and SI joint pain and injury can now be thought of in two broad categories: traumatic and atraumatic. Both categories of SI joint injury are thought to be caused by inflammation or injury of the joint capsule, ligaments, or subchondral bone in the SI joint. Treatment of SI joint pain usually involves a multi-pronged approach, utilizing both, multi-modal medical pain control and interventional pain/surgical techniques such as steroid injections, radiofrequency nerve ablation, and minimally invasive sacroiliac arthrodesis. Though conservative management through multi-modal pain control and physical therapy have their role as first line therapies, an increasing body of evidence supports the use of minimally invasive procedures, both as adjuvant treatments to conservative management and as second line therapies for patient's that fail first line treatment.

Quantitative study on the biomechanical mechanism of sacroiliac joint subluxation: A finite element study

The biomechanical mechanism of sacroiliac joint pain caused by sacroiliac joint subluxation is still unclear. And the purpose of this study is to elucidate the mechanism. In the present study, a finite element model of female lumbar spine-pelvis-femur was established. To simulate the sacroiliac joint subluxation quantitatively, the left ilium was shifted ±1, ±2, and ±3 mm along each axis, respectively. The stress and strain of articular surfaces and ligaments between the sacroiliac joint subluxation model and the normal model were compared. When the left ilium shifted along the positive direction of the X/Y/Z axis, the stress on most articular surfaces of the sacroiliac joint increased, of which the stress on the iliac surface of the right sacroiliac joint increased most obviously. The stress and strain of the ligaments increased most obviously when the left ilium shifted along the Y-axis, of which the left sacrospinous ligament increased the most, followed by the right sacrospinous ligament and right long posterior sacroiliac ligament. While the left long posterior sacroiliac ligament decreased the most, followed by the left short posterior sacroiliac ligament. The present study suggests that when the sacroiliac joint subluxation happens, even a slight shift, different biomechanical changes of different ligaments around the sacroiliac joint will happen. This may lead to an abnormal proprioceptive sensation of the ligaments, resulting in stress imbalance of the sacroiliac joint, and finally resulting in sacroiliac joint pain.

Salvage of Failed Lateral Sacroiliac Joint Fusion with a Novel Posterior Sacroiliac Fusion Device: Diagnostic Approach, Surgical Technique, and Multicenter Case Series

Background

Studies have found that up to one-third of patients with LBP have sacroiliac joint (SIJ) dysfunction as a contributing cause. Historically, the management of SIJ dysfunction has been plagued by ineffectiveness or significant morbidity. In 2008, minimally invasive lateral SIJ fusion was developed. While this procedure is a safe and effective treatment, there is still a significant proportion of patients who will not experience therapeutic success. There is a paucity of data in the literature regarding the management of these patients. Recently, a novel posterior sacroiliac joint fusion device has been developed which minimizes complications compared to lateral approaches and may serve to salvage therapeutic failures in this patient population.

Objective

Determine the efficacy and feasibility of a posterior SIJ fusion device as a salvage technique in patients who have not experienced therapeutic success following lateral SIJ fusion.

Design

Multi-center retrospective observational study.

Methods

Patients who had previously undergone lateral SIJ fusion and had persistent LBP were evaluated and diagnosed to have persistent primary SIJ pathology. All patients underwent posterior SIJ fusion utilizing a machined allograft transfixing sacroiliac fusion device. Demographic data and patient reported pain scores were collected.

Results

A total of 7 patients who had undergone lateral SIJ fusion were included in the study and underwent posterior SIJ fusion. The mean patient reported pain improvement following posterior fusion was 80% with an average follow-up time of 10 months. Median morphine milliequivalents were 20 pre-procedure and 0 post-procedure.

Conclusion

We were able to show significant reductions in pain scores and opioid consumption, which suggests that minimally invasive posterior SIJ utilizing a novel implant and technique may be a viable treatment option to salvage pain relief in this patient population. Further, the favorable safety profile of this posterior technique uniquely positions it to be an appropriate first-line surgical therapy.

Best Practices for Postoperative Management of Posterior Sacroiliac Joint Fusion

Sacroiliac joint (SIJ) pain is a common cause of low back pain. Traditionally, treatment for SIJ joint pain and dysfunction has consisted of physical therapy, medication management, SIJ injections, and SIJ ablations. Improved recognition of the SIJ as an etiology for back pain has led to advances in treatment options. Radiofrequency of the lateral sacral branches has been shown to be effective, though evidence is fraught with inconsistent patient selection, study design and procedural technique. It also does not directly address the mechanical dysfunction of the SIJ. In order to create a more enduring approach SIJ fusion has become an attractive option to reduce pain and to improve function. This method of SI joint treatment requires guidance in the perioperative phase of care from both the physicians and advanced practice providers (APP). In order to improve care and outcomes of those undergoing posterior SI joint fusion the American Society of Pain and Neuroscience appointed an expert panel of physicians and advanced practice providers to create a best practice for the post operative care of this approach. As with any best practice, the panel considered current peer reviewed literature and clinical expertise to create guidance today. This is intended to be a living document with modifications as additional evidence comes to light in data publication. The goals of this paper are to focus on (1) wound care, (2) medication use, (3) physical activity and (4) therapeutic exercises.

All-Internal Limb Lengthening with Simultaneous Corrective Osteotomy After Internal Hemipelvectomy: A Case Report

CASE

A 27-year-old woman with a Grade II chondrosarcoma in the right acetabulum underwent a Type II internal hemipelvectomy with an ischiofemoral fusion. She developed a 7.0-cm functional limb-length discrepancy with adduction of the hip at rest. Four years after surgery, she underwent a corrective osteotomy and limb lengthening with a magnetic lengthening nail. Eleven years after tumor resection and a successful pregnancy, she had symmetric leg lengths and ambulated without an assistive device.

CONCLUSIONS

A magnetic lengthening nail is a viable option for correcting limb-length discrepancies after hemipelvectomy. If necessary, a simultaneous corrective proximal femoral osteotomy can be performed.

Biomechanical study of extramedullary and intramedullary fixation in the treatment of unstable intertrochanteric reversed-tilt fractures of the femur

Background

To investigate the efficacy of the 135° hip screw, 95° intramedullary hip screw (IMHS) and 95° hip screw in the treatment of intertrochanteric reverse dip fracture of the femur.

Methods

We retrospectively analyzed 125 matched pairs of human femurs (median age 64 years) which were osteotomized at a 33° angle in the left femur and extended downward from the minor trochanter to simulate a reverse oblique intertrochanteric fracture. The right femur served as a control. The left femur (n=4) was implanted with a 135° hip screw, 95° hip screw, or IMHS. A strain detector was placed distal to the fracture site to monitor fragment strain. The lateral displacement of the proximal femur was measured by a linear variable differential transformer. An Instron tester measured stiffness, strain, and lateral displacement at 25° adduction, and 90° adduction with vertical loads on the femoral head. A 2 cm gap was then formed at the fracture site to simulate comminution and the mechanical test was repeated.

Results

Before the formation of the gap, there was no significant difference in stiffness among different bone structures (P>0.05), but after the formation of the gap, the stiffness of all the adduction structures decreased (P=0.03), and the difference in adduction was statistically significant (135° hip screw: 46.6%±3%; 95° hip screw: 22.9%±2%; IMHS: 53.7%±7.8%; P<0.05). Similar results were found for the abduction and buckling positions. There was no significant difference in the lateral displacement of the gap before (P=0.92) and after (P=0.26), but a significant difference in the failure load was found (135° hip screw: 1,222±560 N; 95° hip screw: 2,566±283 N; IMHS: 4,644±518 N; P=0.02).

Conclusions

There was no statistically significant difference in stiffness among different structures (P>0.05). However, in the presence of gaps, IMHS bone implant structures are much stiffer than 135° and 95° structures and have a greater destructive load.

The prevalence and clinical characteristics of sacroiliac joint dysfunction in adolescent baseball players

BACKGROUND

Sacroiliac joint (SIJ) dysfunction is a potential source of low back pain (LBP) in baseball players, who are more likely to be affected by loading of the SIJ in the throwing motion. However, the prevalence and characteristics of this condition have not been studied thoroughly. This study aimed to investigate the prevalence and clinical characteristics of SIJ dysfunction among high school baseball players.

METHODS

Participants comprised 891 high school baseball players who had undergone annual medical evaluations (a self-completed questionnaire and physical examination). The prevalence of SIJ dysfunction and associations with the measurements of the flexibility of the spine and lower extremities such as finger-floor-distance, straight-leg-raising angle, heel-buttock-distance, Thomas test, and passive range of motion of the hip were investigated.

RESULTS

Twenty-two of 891 subjects (2.5%) met our criteria for SIJ dysfunction. Twelve subjects (55%) exhibited throwing arm side symptoms more commonly than in the non-throwing arm side (n = 3, 15%) or bilateral side (n = 7, 32%). Previous episodes of LBP were experienced significantly more frequently among subjects with SIJ dysfunction (n = 19, 86.4%) than among those without (n = 501, 57.7%; P = 0.015). The prevalence of present LBP that interfered with play was significantly higher among subjects with SIJ dysfunction (n = 9, 42.9%) than among those without (n = 118, 21.2%; P = 0.038). The prevalence of SIJ dysfunction as a source of LBP was estimated at 7.1% (9 of 127 subjects). After adjustment for associated factors using a logistic regression model, we observed a significant association between a limitation in hip internal rotation on the throwing arm side and SIJ dysfunction (odds ratio 3.11 [1.30-7.71]; P = 0.0109).

CONCLUSIONS

According to our criteria, the estimated prevalence of SIJ dysfunction among high school baseball players is 2.5%. There was a significant association between a limitation in hip internal rotation on the throwing arm side and SIJ dysfunction.

Osteopathic approach to sacroiliac joint pain in pregnant patients

This paper aims to provide a comprehensive review of the management of sacroiliac (SI) joint pain in pregnant patients. Although SI joint pain is highly prevalent among pregnant patients, the unique anatomy of the joint is rarely discussed in a clinical setting. This paper provides comprehensive review of the epidemiology, anatomy, alarm findings, standard treatment, osteopathic assessment, and osteopathic manipulative treatment (OMT) of the SI joint, and it provides a general and in-depth understanding of the SI joint pain in pregnant patients and its management.

Unexpected Sex Differences in the Relationship of Sacroiliac Joint and Lumbar Spine Degeneration

The relationship between degenerative changes of the sacroiliac joints and the lumbar spine on CT has not been studied yet. The aim of this analysis is to determine the nature of their association as well as the influence of fixed anatomical spinopelvic parameters on sacroiliac joint degeneration. For this institutional review-board-approved investigation, imaging datasets as well as electronic medical records of 719 patients without back pain from the clinical routine of our department of radiology were included. Age, sex, weight category (slim, normal, obese), parity in women and indication for imaging were noted for all patients. The presence of degenerative lesions of the lumbar spine (disc degeneration, endplate degeneration, spondylophytes, and facet joint osteoarthritis) was noted separately at each lumbar segment (L1 to L5). Sacroiliac joints were assessed for sclerosis and osteophytes. Fixed anatomical spinopelvic parameters were measured: pelvic radius = PR; pelvic incidence = PI; sacral table angle = STA. Correlation as well as regression analyses were performed; data were analyzed for males and females separately. PI increased significantly with age in both women and men, while STA decreased and PR remained constant; neither of them was associated with SIJ degeneration. SIJ degeneration correlated with disc degeneration (tau = 0.331; p < 0.001), spondylophytes (tau = 0.397; p < 0.001), and facet joint degeneration (tau = 0.310; p < 0.001) in men, but with no parameter of spinal degeneration in women. Lumbar spinal degeneration increased the risk of sacroiliac joint degeneration in men significantly (OR 7.2; 95%CI 2.8–19.0), but it was not a significant covariable in women. Fixed spinopelvic parameters have little impact on sacroiliac joint degeneration. The degeneration of the sacroiliac joints and the lumbar spine appear to be parallel processes in men, but are largely unrelated in women.

Distribution of Acute and Chronic Lesions in the Sacroiliac Joints of Patients with Axial Spondyloarthritis

Objective

In this study, we aimed to investigate whether there was a pattern of distribution of acute and chronic lesions in the sacroiliac joints (SIJ) of patients with axial spondyloarthritis (axSpA).

Methods

A total of 96 patients diagnosed as axSpA were retrospectively included in this study. The Spondyloarthritis Research Consortium of Canada sacroiliac joint inflammation score (SIS) and structural score (SSS) were used to evaluate the acute and chronic lesions in the SIJs. Scores representing the distribution of bone marrow edema, fatty lesions and erosions were extracted respectively. By dividing the SIJs into sacral or iliac sections, upper or lower sections, anterior and posterior levels, differences of scores representing acute and chronic lesions were analyzed by Kruskal Wallis’ tests.

Results

SIS scores were not significantly different in sacral or iliac sections, in upper or lower sections, on anterior or posterior levels. SSS scores were also not significantly different in different sections, except for higher occurrence rates of erosions in the iliac sections. Post-hoc analysis showed that there was a higher erosion score in the left ilium than left sacrum, as well as in right ilium than left sacrum.

Conclusion

There was no specific distribution pattern of acute or chronic lesions in the SIJs in patients with axSpA. A bigger study sample was needed to confirm the distribution of erosions in sacral or iliac sections.

Change in Pelvic Incidence Associated With Sacroiliac Joint Dysfunction: A Case Report

The sacroiliac joint (SIJ) is designed primarily for stability with minute motions. SIJ dysfunction refers to improper movement of the SIJs. Diagnosis and evaluation of SIJ dysfunction are difficult, with use of physical maneuvers and image-guided anesthetic injection. This case report describes a 47-year-old female who experienced right buttock pain and painful limp for approximately 2 months. Standing radiographs revealed inflammatory sclerosis surrounding the right SIJ. Physical examination found tenderness over the right SIJ and positive results in provocation (the distraction, compression, and thigh thrust) tests, compatible with right SIJ dysfunction. Her pain was resolved and gait performance was retrieved following 6-month program of combined thoracolumbar manipulation and rehabilitation exercises. Unexpectedly, change in pelvic incidence (PI) angles was noticed on follow-up radiograph. PI remains more or less fixed throughout adult life since the mobility of the SIJs is considered negligible. The current presentation is designed to explore the significance of PI change. The PI disparity unfolds the possibility of recognizing SIJ dysfunction based on consecutive radiographs.

A Tribological Comparison of Facet Joint, Sacroiliac Joint, and Knee Cartilage in the Yucatan Minipig

OBJECTIVE

Pathology of the facet and sacroiliac (SI) joints contributes to 15% to 45% and 10% to 27% of lower back pain cases, respectively. Although tissue engineering may offer novel treatment options to patients suffering from cartilage degeneration in these joints, the tribological characteristics of the facet and SI joints have not been studied in either the human or relevant large animal models, which hinders the development of joint-specific cartilage implants.

DESIGN

Cartilage was isolated from the knee, cervical facet, thoracic facet, lumbar facet, and SI joints of 6 skeletally mature Yucatan minipigs (Sus scrofa). Tribological characteristics were assessed via coefficient of friction testing, interferometry, and immunohistochemistry for lubricin organization.

RESULTS

Compared with the knee, the coefficient of friction was higher by 43% in the cervical facet, 77% in the thoracic facet, 37% in the lumbar facet, and 28% in the SI joint. Likewise, topographical features of the facet and SI joints varied significantly, ranging from a 114% to 384% increase and a 48% to 107% increase in global and local surface roughness measures, respectively, compared with the knee. Additionally, the amount of lubricin in the SI joint was substantially greater than in the knee. Statistical correlations among the various tribological parameters revealed that there was a significant correlation between local roughness and coefficient of friction, but not global roughness or the presence of lubricin.

CONCLUSION

These location-specific tribological characteristics of the articular cartilages of the spine will need to be taken into consideration during the development of physiologically relevant, functional, and durable tissue-engineered replacements for these joints.

Sacroiliac Joint and Pelvic Dysfunction Due to Symphysiolysis in Postpartum Women

Pregnancy-related pain in the sacroiliac joint (SIJ), lumbosacral region, pubic symphysis, or in any combination of these joints has been coined as pelvic girdle pain (PGP) and has been estimated to affect almost half of all pregnant women. SIJ dysfunction in pregnancy is due to multiple biomechanical mechanisms, such as increased weight, change in posture, increased abdominal and intrauterine pressure, and laxity of the spine and pelvic structures. Moreover, when compared to men, women have increased SIJ mobility due to increased pubic angle and decreased SIJ curvature. These differences may assist in parturition where hormones, such as relaxin and estrogen, cause symphysiolysis. A retrospective review of the literature was conducted in the PubMed database using the search term “pregnancy-related sacroiliac joint pain.” All peer-reviewed studies were included. Around 8%-10% of women with PGP continue to have pain for one to two years postpartum. Patients that were treated with SIJ fusion show statistically significant improvement in pain scores when compared to patients that had non-operative treatment. Although we have a number of studies following patients after sacroiliac (SI) joint fusion for pelvic pain with SI joint dysfunction, further research is needed to study sacroiliac fusion for SI joint dysfunction in postpartum women to better tailor and optimize surgical outcomes for this patient population.

Sacral stress fractures in athletes

PURPOSE

Fatigue stress fractures are a common overuse injury, frequently associated with high load-bearing endurance activities such as running, military training and aerobic exercise. While these fractures can arise at any site, sacral stress fractures are poorly studied with evidence consisting mainly of case reports and limited case series. This review aims to analyze and summarize all reports published to date describing cases of sacral stress fracture in athletes.

METHODS

PubMed, Embase, Web of Science and the Cochrane Database were systematically searched for studies reporting on Stress Fractures of the Sacrum. Insufficiency fractures of the elderly were excluded.

RESULTS

The literature review revealed 49 studies reporting on 124 cases of sacral stress fractures. Seventy-six patients (61%) were professional or collegiate level athletes, and 37 (30%) were military recruits or police officers in training. Seventeen female athletes were identified as suffering from low bone mineral density (25%), 9 of which reported menstrual irregularities. Thirteen female patients (19%) had a history of eating disorders.

CONCLUSION

While most sacral stress fractures occur in normal bones exposed to abnormal repetitive loads, the high percentage of lower bone mineral density can blur the lines between fatigue fractures and insufficiency fractures. The causes of these fractures are multifactorial. High endurance sports and the features of the female athlete triad were found in high percentage of the cases. Conservative treatment is the mainstay of treatment, consisting of ceasing of training and a period of rehabilitation and gradual return to training and competition.

Successful Diagnosis of Sacroiliac Joint Dysfunction

Background

Sacroiliac joint (SIJ) pain is one of the most common causes of low back pain, accounting for 15 to 30% of all cases. Although SIJ dysfunction accounts for a large portion of chronic low back pain prevalence, it is often overlooked or under diagnosed and subsequently under treated. The purpose of this review was to establish a best practices model to effectively diagnose SIJ pain through detailed history, physical exam, review of imaging, and diagnostic block.

Methods

A literature search was performed on the diagnosis of sacroiliac joint pain and sacroiliac joint dysfunction. The authors proposed diagnostic recommendations based upon the available literature and a detailed understanding of diagnosing SIJ pain.

Results

The practitioner must focus on the history, location of pain, observed gait pattern, and perform key points of the physical exam including sacroiliac provocative maneuvers. If the patient exhibits at least three provocative maneuvers then the SIJ may be considered as a possible source of pain. Additionally, a thorough review of the imaging should be performed to rule out other etiologies of low back pain. In the absence of any pathognomonic tests or examination findings, diagnostic SIJ blocks have evolved as the diagnostic standard.

Conclusion

The diagnosis of SIJ pain is a multifaceted process that involves a careful assessment including differentiating other pain generators in the region. This involves careful history taking, appropriate physical examination including provocative maneuvers and diagnostic injections. Once the diagnosis is confirmed, long-term solutions may be considered, including recent advances in sacral lateral branch denervation and sacroiliac joint fusion.

An Omitted Radiological finding in the Pediatric Age Group: Physiological Sacroiliac Joint Vacuum Normal Variant

INTRODUCTION

Gas accumulation in human joint spaces has been generally described as the vacuum phenomenon (VP). To date, the sacroiliac joint VP has been associated mostly with pathological, particularly degenerative conditions (e.g., arthritis, obesity, discal degenerations, fractures, dislocations, avascular necrosis).

OBJECTIVE

The study aimed to examine the characteristics of the physiological form of VP and its radiological patterns in a sample of pediatric patients.

METHODS

A sample of seventy patients between 0 and 17 years old (mean age, 11.4 ± 5.54) were included in the study. Sample VP cases was evaluated according to types, age group, anatomic localization, gender, and sides. RESULTS: Two (2.9%) of sample children had degenerative VP, with 24 (34.2%) of patients demonstrating physiological VP in the sacroiliac joints. VP rates significantly increased after nine years of age (p < 0.01) and 83% of physiological VP cases were determined to be bilateral.

CONCLUSIONS

Although degenerative VP is a rare entity in children, non-pathological VP can be a more common aspect of sacroiliac anatomy. Although sacroiliac VP is frequently an underreported or omitted finding in imaging studies, this condition may be clinically important as a clue for other degenerative diagnoses. Normal variants of VP may be clinically important in children since they may mimic inflammatory and infectious pathologies during magnetic resonance imaging and computed tomography images.

Immediate Effects of Myofascial Release on the Thoracolumbar Fascia and Osteopathic Treatment for Acute Low Back Pain on Spine Shape Parameters: A Randomized, Placebo-Controlled Trial

BACKGROUND

Spine shape parameters, such as leg length and kyphotic or lordotic angle, are influenced by low back pain. There is also evidence that the thoracolumbar fascia plays a role in such pathologies. This study examined the immediate effects of a myofascial release (MFR) technique on the thoracolumbar fascia and of an osteopathic treatment (OMT) on postural parameters in patients with acute low back pain (aLBP).

METHODS

This study was a single-blind randomized placebo-controlled trial. Seventy-one subjects (43.8 ± 10.5 years) suffering from aLBP were randomly and blindedly assigned to three groups to be treated with MFR, OMT, or a placebo intervention. Spinal shape parameters (functional leg length discrepancy (fLLD), kyphotic angle, and lordotic angle) were measured before and after the intervention using video raster stereography.

RESULTS

Within the MFR group, fLLD reduced by 5.2 mm, p < 0.001 and kyphotic angle by 8.2 degrees, p < 0.001. Within the OMT group, fLLD reduced by 4.5 mm, p < 0.001, and kyphotic angle by 8.4°, p = 0.007.

CONCLUSION

MFR and OMT have an influence on fLLD and the kyphotic angle in aLBP patients. The interventions could have a regulating effect on the impaired neuromotor control of the lumbar muscles.

Anatomical Joint Form Variation in Sacroiliac Joint Disease: Current Concepts and New Perspectives

Purpose of Review

The aim of this article is to further the understanding of anatomical variation of the sacroiliac joint (SIJ) within the rheumatological community and point out promising fields of research in the interplay of SIJ anatomy and joint disease.

Recent Findings

Mechanical strain has long been implicated in onset and progression of axial spondyloarthritis (axSpA). Recent investigations found changes in the pattern of degenerative lesions of the SIJ in the normal population in patients with atypical joint forms. Furthermore, atypical SIJ forms are more prevalent in patients with axial spondyloarthritis and mechanical SIJ disease.

Summary

Mechanical stress from anatomical joint form variation may have an impact on development and progression of axSpA. Furthermore, mechanically induced bone marrow edema may act as an axSpA mimic on MRI and needs to be more accurately classified.

Sacroiliac joint stabilization using implants provide better fixation in females compared to males: a finite element analysis

PURPOSE

This study's objective was to assess biomechanical parameters across fused and contralateral sacroiliac joints (SIJs) and implants during all spinal motions for both sexes. Various SIJ implant devices on the market are used in minimally invasive surgeries. These implants are placed across the joint using different surgical approaches. The biomechanical effects of fusion surgical techniques in males and females have not been studied.

METHODS

The validated finite element models of a male, and a female spine-pelvis-femur were unilaterally instrumented across the SIJ using three screws for two SIJ implants, half threaded and fully threaded screws placed laterally and posteriorly to the joint, respectively.

RESULTS

Motion and peak stress data at the SIJs showed that the female model exhibited lower stresses and higher reduction in motion at the contralateral SIJ in all motions than the male model predictions with 84% and 71% reductions in motion and stresses across the SIJ.

CONCLUSION

Implants exhibited higher stresses in the female model compared to the male model. However, chances of SIJ implant failure in the female patients are still minimal, based on the calculated factor of safety which is still very high. Both lateral and posterior surgical approaches were effective in both sexes; however, the lateral approach may provide a better biomechanical response, especially for females. Moreover, implant design characteristics did not make a difference in the implants' biomechanical performance. SIJ stabilization was primarily provided by the implants which were the farthest from the sacrum rotation center.

Impact of age, sex, and joint form on degenerative lesions of the sacroiliac joints on CT in the normal population

Degeneration of the sacroiliac joints (SIJs) is a common finding, while its underlying cause and development remain incompletely understood. The aim of this investigation was to describe the spatial distribution of degenerative SIJ changes across age groups and to investigate for the first time their relationship to anatomical form and sex. For this IRB-approved investigation, demographic data of 818 patients without SIJ disease were retrieved from electronic patient records. High-resolution computed tomography (CT) datasets of all patients were analysed retrospectively for seven predefined age groups (ten-year increments, from < 25 to ≥ 75). A structured scoring system was applied to assess sclerosis, osteophytes, joint space alterations, and anatomical form. Chi-square tests were used to compare frequencies of degenerative lesions, and logistic regression analyses were performed to investigate associations between demographic data, anatomical form, and the presence of structural lesions. Sclerosis and osteophytes were common findings, with an overall prevalence of 45.7% and 46.8%, respectively. Female sex had an odds ratio (OR) of 0.15 (95% CI: 0.08-0.27) for the presence of ventral osteophytes and of 4.42 (95% CI: 2.77-7.04) for dorsal osteophytes. Atypical joint forms were significantly more prevalent in women with 62.1% vs. 14.1% in men (p < 0.001). Accessory joints increased the likelihood of dorsal sclerosis (OR 2.735; 95% CI 1.376-5.436) while a typical joint form decreased its likelihood (OR 0.174; 95% CI 0.104-0.293). Sex and anatomical joint form have a major impact on the development of degenerative lesions of the SIJs and their spatial distribution.

Role of the Pubic Symphysis in Osseous Pelvic Development: A Novel Model of Bladder Exstrophy in Rabbits

BACKGROUND

It has been posited that the osseous pelvic anomalies seen in patients with classic bladder exstrophy (CBE) result from disruption of the pubic symphysis. This hypothesis, however, has not been tested. In the present animal study, our objective was to determine whether the tension of the pubic symphysis helps maintain the shape of the pelvic ring, or whether the growing bones maintain a ring shape even without the tension of the symphysis.

METHODS

In total, 12 neonatal New Zealand White rabbits underwent pubic symphysiotomy (experimental group, n=9) or sham surgery (control group, n=3) on days 3 or 4 of life. Rabbits were scanned with cone-beam computed tomography at 1, 4, 12, and 20 weeks postoperatively to monitor changes in the following pelvic parameters, which are known to be altered in CBE: anterior segment angle, anterior segment length, intertriradiate distance, interpubic distance, and posterior segment angle. Changes within the experimental and control groups were evaluated using repeated-measures analysis of variance and post hoc Tukey honest significant difference testing. Two-tailed t tests were used to compare treatment groups at each time point.

RESULTS

Both groups showed increases in anterior segment length and intertriradiate distance during the study period; rabbits in the experimental group also showed a steady increase in interpubic distance (F=43.9; P<0.001). Experimental rabbits had significantly larger mean values for anterior segment angle, intertriradiate distance, interpubic distance, and posterior segment angle than did control rabbits at all time points. We found no difference in mean anterior segment length between control and experimental groups at any time point. The difference in interpubic distance was particularly pronounced by 20 weeks (experimental group, 13±2.7 mm; control group, 1.1±0.1 mm; P<0.001).

CONCLUSIONS

The pubic symphysis is essential for normal pelvic development. Its absence led to early pelvic angulation and progressive pubic separation in a rabbit model. However, we found no significant difference in the mean anterior segment length, and it is likely that other factors are also implicated in the growth disturbance seen in CBE.

LEVEL OF EVIDENCE

Level V.

Sacroiliac Joint Dysfunction Treated Using Neural Therapy to the Temporomandibular Joint: A Case Report

Temporomandibular joint disorders (TMJD) include temporomandibular joint dysfunction and bruxism. Sacroiliac joint dysfunction (SJD) is a frequent cause of non-discogenic low back pain. Studies suggest a relationship between TMJD and SJD; however, the link remains unclear. Neural therapy (NT) utilises local anaesthetic injections to treat pain by normalising a dysfunctional autonomic nervous system held responsible for initiating or propagating chronic pain. A 31-year-old female presented with a 1-year history of mechanical left-sided low back pain and sleep bruxism. Examination revealed crepitation of the left TMJ and a trigger point in the masseter muscle. Range of motion of the spine and hip joints were normal, Patrick and Geanslen tests were positive on the left side. Spine and standing flexion tests were also positive. Magnetic resonance imaging of the lumbar spine and sacroiliac joints were normal. A diagnosis of SJD was made, and the patient was treated using NT. Injections of lidocaine 0.5% to the left TMJ, the masseter muscle and intradermal segmental injections at the level of C4 were administered. The patient's back pain and TMJ tenderness reduced and continued so throughout the 3-month follow-up period. SJD may be related to TMJD, and NT may be used in its treatment.

International Society for the Advancement of Spine Surgery Policy 2020 Update-Minimally Invasive Surgical Sacroiliac Joint Fusion (for Chronic Sacroiliac Joint Pain): Coverage Indications, Limitations, and Medical Necessity

The index 2014 International Society for the Advancement of Spine Surgery Policy Statement-Minimally Invasive Surgical Sacroiliac Joint Fusion-was generated out of necessity to provide an International Classification of Diseases, Ninth Revision (ICD-9)-based background and emphasize tools to ensure correct diagnosis. A timely ICD-10-based 2016 update provided a granular threshold selection with improved level of evidence and a more robust and relevant database (Appendix Table A1). As procedures and treatment options have evolved, this 2020 update reviews and analyzes the expanding evidence base and provides guidance relating to differences between the lateral and dorsal surgical procedures for minimally invasive surgical sacroiliac joint fusion.

Pelvic Girdle Pain, Hypermobility Spectrum Disorder and Hypermobility-Type Ehlers-Danlos Syndrome: A Narrative Literature Review

Pelvic girdle pain (PGP) refers specifically to musculoskeletal pain localised to the pelvic ring and can be present at its anterior and/or posterior aspects. Causes such as trauma, infection and pregnancy have been well-established, while patients with hypermobile joints are at greater risk of developing PGP. Research exploring this association is limited and of varying quality. In the present study we report on the incidence, pathophysiology, diagnostic and treatment modalities for PGP in patients suffering from Hypermobility Spectrum Disorder (HSD) and Hypermobility-Type Ehlers-Danlos Syndrome (hEDS). Recommendations are made for clinical practice by elaborating on screening, diagnosis and management of such patients to provide a holistic approach to their care. It appears that this cohort of patients are at greater risk particularly of mental health issues. Moreover over, they may require a multidisciplinary approach for their management. Ongoing research is still required to expand our understanding of the relationship between PGP, HSD and hEDS by appropriately diagnosing patients using the latest updated terminologies and by conducting randomised control trials to compare outcomes of interventions using standardised patient reported outcome measures.

The Cranial Bowl in the New Millennium and Sutherland's Legacy for Osteopathic Medicine: Part 2

Cranial osteopathic medicine is practiced all over the world, respecting the dictates of the creator, Dr Sutherland. Despite the current manual approach faithfully follows the theoretical and practical bases that make up the cranial model of the last century, there are many scientific evidences that highlight the criticalities of the same model. In the first part we reviewed the role of the meninges and cerebrospinal fluid (CSF), as well as we discussed some rhythms present in the central nervous system; these latter elements are the pillars to support the theoretical idea of the movement of the skull evaluated and palpated by the osteopath. In this second part we will review the mechanical characteristics of other structures that make up the cranial system, highlighting new perspectives for clinical practice, thanks to the most recent data derived from scientific research.

Comparison of sacroiliac joint degeneration between patients with sagittal imbalance and lumbar spinal stenosis

PURPOSE

The purpose of this study was to compare the degeneration of sacroiliac joints (SIJs) between adult spinal deformity (ASD) patients with sagittal imbalance and an age- and sex-matched lumbar spinal stenosis (LSS) patients without sagittal imbalance.

MATERIALS AND METHODS

The age- and sex-matched case-control study consists of two groups: the ASD group and the other group consisting of patients with LSS (LSS group). The study population consisted of 98 patients in each group. The spinopelvic parameters such as pelvic incidence (PI), sacral slope, pelvic tilt, lumbar lordosis, and sagittal vertical axis (SVA) were measured. To evaluate degeneration of SIJ, two protocols (Backlund's grade and Eno's classification) were used.

RESULT

SIJ degeneration in the ASD group was more severe than that in the LSS group, as assessed by both Backlund's grade and Eno's classification (P < 0.001 for both). Age correlated significantly with PI in both the ASD and LSS groups (r = 0.285; P = 0.005, r = 0.218; P = 0.031, respectively). The total Backlund's grading score and the SVA were significantly correlated with PI in the ASD group (r = 0.344; P < 0.001, r = 0.276; P = 0.007, respectively), but not in the LSS group (r = 0.156; P = 0.126, r = 0.189; P = 0.067, respectively).

CONCLUSIONS

ASD patients with sagittal imbalance demonstrated more severe SIJ degeneration compared to the age- and sex-matched LSS group. PI was significantly correlated with both SIJ degeneration and SVA only in the ASD group.

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.