MRI in Axial Spondyloarthritis: Position Statements from the Hong Kong Society of Rheumatology

The Hong Kong Society of Rheumatology (HKSR) has developed evidence-based position statements on the use of magnetic resonance imaging (MRI) in axial spondyloarthritis (axSpA). A special interest group (SIG) developed the statements based on the literature review of the following research questions: 1) In whom should SI joint MRI be done to diagnose axSpA? 2) Should spine MRI be performed for diagnosis of axSpA? 3) Should spine and SI joint MRI be used in the assessment and monitoring of disease activity? 4) Which MRI sequence(s) should be used in axSpA? These statements have at least 75% agreement from voting rheumatology fellows of HKSR, and are developed to serve as local practice guidelines for rheumatologists and musculoskeletal radiologists in the management of axSpA.

Investigating the Etiology and Diagnosis of Sacroiliac Joint Pain

The sacroiliac (SI) joint is often characterized as a large, auricular-shaped, and diarthrodial synovial joint. The SI ligamentous structure is more extensive in the dorsal part due to the absence of the posterior capsule, which functions as a connecting band between the sacrum and ilium. In addition, a network of muscles supports the SI joint that helps deliver regional muscular forces to the pelvic bones. The third and fourth decades of life promote senescent changes manifested by surface irregularities, crevice formation, fibrillation, and clumping of chondrocytes.

Sacroiliac Joint Variation in Patients With Ossification of the Posterior Longitudinal Ligament

Study Design: Retrospective Cohort Study. Objectives: Ossification of the posterior longitudinal ligament (OPLL) reveals heterotopic ossification in the spinal ligament. OPLL also tends to ossify ligaments and entheses throughout the body. However, hallmarks of sacroiliac (SI) joint ossification and its variation in OPLL have not been clarified. Here, we investigated the morphological changes in SI joints in individuals with and without OPLL. Methods: We included 240 age- and sex-matched patients (OPLL+, 120; OPLL−, 120) in the study. SI joint variations were classified into 4 types: Type 1, normal or small peripheral bone irregularity; Type 2, subchondral bone sclerosis and osteophyte formation; Type 3, vacuum phenomenon; and Type 4, bridging osteophyte and bony fusion. Type 4 was further divided into 3 subgroups as previously described. Interactions between the ossified spinal region in OPLL and morphological changes in the SI joint were evaluated. Results: SI joint ankylosis occurs more frequently in patients with OPLL (51.7%) than in those without (non-OPLL) (33.3%). The SI joint vacuum phenomenon (49.2%) was the main finding in non-OPLL. SI joint ankylosis in OPLL was characterized by anterior bridging and intra-articular fusion. OPLL patients with multilevel ossification tend to develop degeneration and ankylosis of the SI joints. Conclusions: OPLL conferred a high risk of SI joint ossification compared with non-OPLL, and patients with extensive ossification had a higher rate of SI joint ankylosis. Understanding SI joint variation could help elucidate OPLL etiology and clarify the phenotypic differences in the SI joint between OPLL and other spinal disorders.

Bilateral open sacroiliac joint fusion during adult spinal deformity surgery using triangular titanium implants: technique description and presentation of 21 cases

OBJECTIVE Pelvic fixation enhances long constructs during deformity surgery. Subsequent loosening of iliac screws and pain at the pelvis occur in as many as 29% of patients. Concomitant sacroiliac (SI) fusion may prevent potential pain and failure. The objective of this study was to describe a novel surgical technique and a single institution’s experience using bilateral SI fusion during adult deformity surgery with S2-alar-iliac (S2AI) screws and triangular titanium rods (TTRs) placed with navigation. METHODS The authors reviewed open SI joint fusions with TTR performed between August 2019 and March 2020. All patients underwent lumbosacral fusion through a midline approach and bilateral S2AI pelvic fixation in the caudal teardrop, followed by TTR placement just proximal and cephalad to the S2AI screws using intraoperative CT imaging guidance. RESULTS Twenty-one patients were identified who received 42 TTRs, ranging in size from 7.0 × 65 mm to 7.0 × 90 mm. Three TTRs (7%) were malpositioned intraoperatively, and each was successfully repositioned during index surgery without negative sequelae. All breaches occurred in a medial and cephalad direction into the pelvis. Incremental operative time for adding TTR averaged 8 minutes and 33 seconds per implant. CONCLUSIONS Image-guided open SI joint fusion with TTR during lumbosacral fusion is technically feasible. The bony corridor for implant placement is narrower cephalad, and implants tend to deviate medially into the pelvis. Detection of malpositioned implant is aided with intraoperative CT, but this can be salvaged. A prospective randomized clinical trial is underway that will better inform the impact of this technique on patient outcomes.

Orthopedic management of pubic symphysis osteomyelitis: a case series

Objectives: The purpose of this case series is to describe the orthopedic management of pubic symphysis osteomyelitis with an emphasis on the key principles of treating bony infection. Furthermore, we sought to identify whether debridement of the pubic symphysis without subsequent internal fixation would result in pelvic instability. Methods: A retrospective chart review was performed to identify all cases of pubic symphysis osteomyelitis treated at both institutions from 2011 to 2020. Objective outcomes collected included infection recurrence, change in pubic symphysis diastasis, sacroiliac (SI) joint diastasis, and ambulatory status. Subjective outcome measures collected included the numeric pain rating scale (NPRS) and the 36-Item Short Form Survey (SF-36). Pubic symphysis diastasis was measured as the distance between the two superior tips of the pubis on a standard anterior–posterior (AP) view of the pelvis. SI joint diastasis was measured bilaterally as the joint space between the ileum and sacrum approximately at the level of the sacral promontory on the inlet view of the pelvis. A paired t test was utilized to compare the differences in outcome measures. An α value of 0.05 was utilized. Results: Six patients were identified, of which five were males and one was female (16.7 %), with a mean ± standard deviation (SD) follow-up of 19 ± 12 months (range 6–37 months). Mean ± SD age was 76.2 ± 9.6 years (range 61.0–88.0 years) and body mass index (BMI) was 28.0 ± 2.9 kg/m2 (range 23.0–30.8 kg/m2). When postoperative radiographs were compared to final follow-up radiographs, there were no significant differences in pubic symphysis diastasis (P = 0.221) or SI joint diastasis (right, P = 0.529 and left, P = 0.186). All patients were ambulatory without infection recurrence at final follow-up. Mean improvement for NPRS was 5.6 ± 3.4 (P = 0.020) and mean improvement for SF-36 physical functioning was 53.0 ± 36.8 (P = 0.032). Conclusion: This case series highlights our treatment strategy for pubic symphysis osteomyelitis of aggressive local debridement with local antibiotic therapy. Additionally, debridement of the pubic symphysis without subsequent internal fixation did not result in pelvic instability, as determined by pelvic radiographs and ability to fully weight bear postoperatively.

Communicative Functions in Children Raised in Three Different Social Contexts in Colombia: The Key Issue of Joint Attention

Children’s sociocultural experiences vary around the world. Colombia is a South American country where the differences between socioeconomic statuses (SES) are huge. In this study, through the ECSP-E Scale, translated to Spanish and validated for linguistic and cultural equivalence, the development of three communicative functions was evaluated through an interactive sociopragmatic approach. The participants comprised 36 24-month-old children, raised in three different social contexts in Colombia, with the goal of comparing them across groups of SES. The lowest SES group sample subjects were representative of extreme poverty and members of an ethnic group, the Wayuú. Results for the communicative functions, namely social interaction (SI), joint attention (JA), and behavior regulation (BR), showed that the only function with no significant differences across SES was joint attention. This supports the hypothesis that the development of this function may be universal, in light of the fact that the Wayuú not only differed from other subjects in terms of their socioeconomic status but also in their culture. Higher SES was related to better social interaction, while Low SES was associated with better behavior regulation than their High SES peers. Consequently, results are discussed considering socioeconomic and cultural differences in the development of communication and social interactions, leading us to reexamine the paradigms, theories, and practices that are used when observing children raised in very poor environments.

Irreducible Overlapping Pubic Symphysis Dislocation Managed with Distraction Osteotomy of the Contralateral Superior Pubic Ramus: A Rare Case Report

Introduction: Overlapping pubic symphysis dislocation (OPSD) or a locked pubic symphysis is a compression of the pelvic ring with the intact pubis trapped into the contralateral obturator foramen. Reduction can be difficult and contralateral suprapubic osteotomy is a good way to address the irreducible OPSD. The technique has only been discussed thrice in the available literature. Case Report: We report the case of a 26-year-old man who had his right pubic ramus entrapped within the contralateral obturator foramen, having an overlap of >4 cm with associated ipsilateral sacroiliac joint (SI joint) disruption and urethral injury. When all the maneuvers of closed and instrumented open reduction failed, we performed a superior pubic ramus osteotomy on the left side and unlocked the incarcerated right pubic ramus. The osteotomy site was stabilized with a 6-hole recon plate and SI joint was stabilized with a 6.5mm percutaneous sacroiliac screw. The patient underwent delayed urethral repair at 10 weeks after the index surgery. At 3-year follow-up, the patient did not report any pubic discomfort, urinary and sexual problems. Conclusion: Locked OPSD is a rare injury and is frequently associated with sacroiliac and urethral injuries. Distraction osteotomy of the contralateral superior pubic ramus is a viable option for irreducible cases. Keywords: Lateral compression injury, locked symphysis pubis, superior pubic ramus osteotomy, overlapping pubic symphysis dislocation.

Prevalence of sacroiliac joint dysfunction in college students

Introduction and Aim: Sacroiliac (SI) joint is considered as one of the pain generators in students. Sacroiliac joint dysfunction is one of the common sources of low back pain, and many times the SI joint dysfunction mis-lead as the lumbar problem. Students who sit for longer duration cause stress in the sacroiliac joint. So, this study intended to investigate the prevalence and the contributing risk factors amongst students’ population with work-related musculoskeletal problems and also to identify the percentage of SI joint involvement in them.Materials and Methods: The study was conducted with 590 students from a private paramedical college, involving full time college students, with age group of 17-27 years, no recent falls or those not on current medications related to any musculoskeletal problems, and students without any congenital problems. Evaluation was done using Nordic musculoskeletal questionnaire along with a self-developed demographic questionnaire. The involved students were assessed using questionnaire and sacroiliac joint tests to identify the SI Joint dysfunction. Provocation tests included i) Sacroiliac joint distraction test, ii) SI Compression test iii) Thigh thrust test iv) Faber’s test and v) Gaenslen’s Test. Inference considered was presence of pain in more than 3 test indicates Sacroiliac joint involvement. On completion of assessment, a thank you card was given to all the volunteer students participated in the study. The collected data was filled and analyzed.Results: The study results showed that students with lower back pain also had complaints of neck pain. It was also noted that about 30% of the individuals were positive to the sacroiliac joint tests, among them 93 participants complained of low back pain.Conclusion: This study concluded that 61% of individuals were suffering with musculoskeletal disorders in the selected population. Around 30% of the low back pain participants complained of sacroiliac joint dysfunctions.

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.

Biomechanical effects of a novel posteriorly placed sacroiliac joint fusion device integrated with traditional lumbopelvic long-construct instrumentation

OBJECTIVE S2-alar-iliac (S2AI) screw fixation effectively ensures stability and enhances fusion in long-segment constructs. Nevertheless, pelvic fixation is associated with a high rate of mechanical failure. Because of the transarticular nature of the S2AI screw, adding a second point of fixation may provide additional stability and attenuate strains. The objective of the study was to evaluate changes in stability and strain with the integration of a sacroiliac (SI) joint fusion device, implanted through a novel posterior SI approach, supplemental to posterior long-segment fusion. METHODS L1-pelvis human cadaveric specimens underwent pure moment (7.5 Nm) and compression (400 N) tests in the following conditions: 1) intact, 2) L2–S1 pedicle screw and rod fixation with L5–S1 interbody fusion, 3) added S2AI screws, and 4) added bilateral SI joint fixation (SIJF). The range of motion (ROM), rod strain, and screw bending moments (S1 and S2AI) were analyzed. RESULTS S2AI fixation decreased L2–S1 ROM in flexion-extension (p ≤ 0.04), L5–S1 ROM in flexion-extension and compression (p ≤ 0.004), and SI joint ROM during flexion-extension and lateral bending (p ≤ 0.03) compared with S1 fixation. SI joint ROM was significantly less with SIJF in place than with the intact joint, S1, and S2AI fixation in flexion-extension and lateral bending (p ≤ 0.01). The S1 screw bending moment decreased following S2AI fixation by as much as 78% in extension, but with statistical significance only in right axial rotation (p = 0.03). Extending fixation to S2AI significantly increased the rod strain at L5–S1 during flexion, axial rotation, and compression (p ≤ 0.048). SIJF was associated with a slight increase in rod strain versus S2AI fixation alone at L5–S1 during left lateral bending (p = 0.048). Compared with the S1 condition, fixation to S2AI increased the mean rod strain at L5–S1 during compression (p = 0.048). The rod strain at L5–S1 was not statistically different with SIJF compared with S2AI fixation (p ≥ 0.12). CONCLUSIONS Constructs ending with an S2AI screw versus an S1 screw tended to be more stable, with reduced SI joint motion. S2AI fixation decreased the S1 screw bending moments compared with fixation ending at S1. These benefits were paired with increased rod strain at L5–S1. Supplementation of S2AI fixation with SIJF implants provided further reductions (approximately 30%) in the sagittal plane and lateral bending SI joint motion compared with fixation ending at the S2AI position. This stability was not paired with significant changes in rod or screw strains.