Imaging Assessment of Nontraumatic Pathologic Conditions at the Craniovertebral Junction: A Comprehensive Review.

Nontraumatic pathologic conditions of the craniovertebral junction encompass a range of conditions affecting the complex anatomy of this region without direct physical injury. These conditions include congenital syndromes that predispose individuals to ligamentous laxity, potentially leading to instability. Additionally, rare but noteworthy cases such as Grisel syndrome, a cause of pediatric torticollis, may arise without a traumatic trigger. Inflammatory diseases, including rheumatoid arthritis, ankylosing spondylitis, and crystal deposition, can lead to cervical instability and spinal cord compression. Infections at the upper cervical spine are dominated by tuberculosis, typically transmitted through hematologic or lymphatic routes with characteristic imaging findings. On the other hand, purulent bacterial infections in this area are rare. Furthermore, although tumors involving the structures of the craniovertebral junction are infrequent, they can lead to significant complications, albeit less frequently through cord compression and more commonly via pathologic fractures or subluxation. The craniocervical junction is a complex anatomic region comprising ligaments, bones, joints, and muscles that support the head's weight and enable its wide range of motion. Accurate recognition and understanding of the complex anatomy and the various nontraumatic pathologic conditions at the craniovertebral junction are pivotal for initiating timely and appropriate treatment strategies. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

The utilization of decision trees on orthopantomographic and lateral panoramic graphs for the diagnosis of unilateral anterior disc displacement of the temporomandibular joint.

BACKGROUND: Investigation is to utilize decision trees in conjunction with orthopantomography (OPT) and lateral panoramic graphy (LPG) to diagnose unilateral anterior disc displacement (ADD) of the temporomandibular joint. METHODS: In this study, 161 patients with images obtained through all three imaging methods, MRI, OPT, and LPG, were selected from the archives. The participants were categorized into two groups: the study group, comprising 89 patients with unilateral anterior disc displacement, and the control group, consisting of 72 healthy individuals. Measurements, including 2 angles (antero-posterior angle and superior-inferior angle) and 3 distance parameters (anterior joint space distance, superior joint space distance, and posterior joint space distance), were conducted on each imaging modality dataset. To assess the obtained measurement data within each patient, the differences from each measurement were calculated. Statistical analysis of the measurement differences between the control and study groups was carried out with independent t test, and decision trees were generated using the SPSS 25 decision tree module 5.0. RESULTS: In ADD patients, it was statistically significantly found that the APA increased while the SIA decreased for angle measurements. But for linear measurements, AS increased while the SS and PS decreased in MRI, OPT, and LPG. CONCLUSION: ADD can be diagnosed in OPT and LPG. The identification of the specific type of ADD that occurs in the temporomandibular joint is not feasible.

Assessment of gait mechanics and muscle strength in hypermobile Ehlers Danlos Syndrome.

BACKGROUND: Hypermobile Ehlers Danlos Syndrome, a heritable connective tissue disorder, is associated with muscle dysfunction, joint subluxations and pain. The impact of hypermobile Ehlers Danlos Syndrome on musculoskeletal mechanics is understudied. Therefore, the aim of this study was to assess the effects of hypermobile Ehlers Danlos Syndrome on lower extremity gait mechanics and muscle strength. METHODS: Eleven people with hypermobile Ehlers Danlos Syndrome and 11 asymptomatic controls underwent a 3D gait analysis and isometric hip and knee muscle strength assessment. Joint subluxations were self-reported by the hypermobile Ehlers Danlos syndrome group. Independent t-tests and Mann Whitney U tests were used to analyze joint mechanics, muscle strength, and patient report outcomes (p < 0.05). FINDINGS: Both groups exhibited similar walking speeds as well as similar hip, knee, and ankle joint kinematics. The hypermobile Ehlers Danlos Syndrome group walked with a lower peak hip extensor moment (hypermobile Ehlers Danlos Syndrome: -0.52 ± 0.28 Nmˑkg-1, Control: -0.83 ± 0.26 Nmˑkg-1, p = 0.01) yet similar knee and ankle joint moments. The hypermobile Ehlers Danlos Syndrome group exhibited a 40% deficit in peak hip extensor strength (hypermobile Ehlers Danlos Syndrome:1.07 ± 0.53 Nmˑkg-1, Control: 1.77 ± 0.79 Nmˑkg-1, p = 0.04). Approximately 73%, 55% and 45% of the hypermobile Ehlers Danlos Syndrome cohort self-reported hip, knee/patella and ankle joint subluxations, respectively, at least once a week. INTERPRETATION: Patients with hypermobile Ehlers Danlos Syndrome ambulated with altered hip extensor moments and exhibit hip extensor weakness. Future work should investigate the underlying mechanisms of hip extensor weakness and corresponding effects on joint health in people with hypermobile Ehlers Danlos Syndrome.

Application of a Low-cost, High-fidelity Proximal Phalangeal Dislocation Reduction Model for Clinician Training.

Introduction: Patients present to the emergency department (ED) relatively commonly with traumatic closed proximal interphalangeal joint (PIPJ) dislocations, an orthopedic emergency. There is a paucity of teaching models and training simulations for clinicians to learn either the closed dislocated dorsal or volar interphalangeal joint reduction technique. We implemented a teaching model to demonstrate the utility of a novel reduction model designed from three-dimensional (3D) printable components that are easy to connect and do not require further machining or resin models to complete. Methods: Students watched a two-minute video and a model demonstration by the authors. Learners including emergency medicine (EM) residents and physician assistant fellows assessed model fidelity, convenience, perceived competency, and observed competency. Results: Seventeen of 21 (81%) participants agreed the model mimicked dorsal and volar PIPJ dislocations. Nineteen of 21 (90%) agreed the model was easy to use, 21/21 (100%) agreed the dorsal PIPJ model and 20/21 (95%) agreed the volar PIPJ model improved their competency. Conclusion: Our 3D-printed, dorsal and volar dislocation reduction model is easy to use and affordable, and it improved perceived competency among EM learners at an academic ED.

Hemiarthroplasty Versus Total Hip Arthroplasty for Femoral Neck Fracture in Elderly Patients: Twelve-Month Risk of Revision and Dislocation in an Instrumental Variable Analysis of Medicare Data.

BACKGROUND: There is practice variation in the selection of a total hip arthroplasty (THA) or a hemiarthroplasty (HA) for the treatment of displaced femoral neck fractures in elderly patients. Large data sets are needed to compare the rates of rare complications following these procedures. We sought to examine the relationship between surgery type and secondary hip surgery (revision or conversion arthroplasty) at 12 months following the index arthroplasty, and that between surgery type and dislocation at 12 months, among elderly Medicare beneficiaries who underwent THA or HA for a femoral neck fracture, taking into account the potential for selection bias. METHODS: We performed a population-based, retrospective study of elderly (>65 years of age) Medicare beneficiaries who underwent THA or HA following a femoral neck fracture. Two-stage, instrumental variable regression models were applied to nationally representative Medicare medical claims data from 2017 to 2019. RESULTS: Of the 61,695 elderly patients who met the inclusion criteria, of whom 74.1% were female and 92.2% were non-Hispanic White, 10,268 patients (16.6%) underwent THA and 51,427 (83.4%) underwent HA. The findings from the multivariable, instrumental variable analyses indicated that treatment of displaced femoral neck fractures with THA was associated with a significantly higher risk of dislocation at 12 months compared with treatment with HA (2.9% for the THA group versus 1.9% for the HA group; p = 0.001). There was no significant difference in the likelihood of 12-month revision/conversion between THA and HA. CONCLUSIONS: The use of THA to treat femoral neck fractures in elderly patients is associated with a significantly higher risk of 12-month dislocation, as compared with the use of HA, although the difference may not be clinically important. A low overall rate of dislocation was found in both groups. The risk of revision/conversion at 12 months did not differ between the groups. LEVEL OF EVIDENCE: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

The V angle compliments radiographic assessment of acute acromioclavicular joint dislocations by differentiating between Rockwood types III versus V and by considering dynamic horizontal translation in coronal radiographs.

PURPOSE: Acromioclavicular joint (ACJ) dislocations are usually graded radiographically according to Rockwood, but differentiation between Rockwood types III and V may be ambiguous. The potentially clinically relevant horizontal instability is barely addressed in coronal radiographs. It was hypothesized that a new radiologic parameter (V angle) would complement ACJ diagnostics on anteroposterior radiographs by differentiating between cases of Rockwood III and V while also considering the aspect of dynamic horizontal translation (DHT). METHODS: Ninety-five patients with acute ACJ dislocations (Rockwood types III and V) were included retrospectively between 2017 and 2020. On anteroposterior views (weightbearing: n = 62, non-weight-bearing: n = 33), the coracoclavicular (CC) distance and the newly introduced V angle for assessing scapular orientation were measured bilaterally. This angle is referenced between the spinal column and a line crossing the superior scapular angle and the crossing point between the supraspinatus fossa and the medial base of the coracoid process, reported as the side-comparative difference (non-injured side *minus* injured side). DHT on Alexander views was divided into stable, partially unstable or completely unstable. RESULTS: The V angle on the injured side alone (mean 50.0°; 95% confidence interval (CI), 48.6°-51.3°) showed no correlation with the side-comparative CC distance [%] (r = - 0.040; n.s.). Thus, the V angle on the non-injured side was considered, displaying a normal distribution (n.s.) with a mean of 58.0° (95% CI, 56.6°-59.4°). The side-comparative V angle showed a correlation with the side-comparative CC distance (r = 0.83; p < 0.001) and was able to differentiate between Rockwood types III (4.7°; 95% CI, 3.9°-5.5°; n = 39) and V (10.3°; 95% CI, 9.7°-11.0°; n = 56) (p < 0.001). A cut-off value of 7° had a 94.6% sensitivity and an 82.1% specificity (area under curve, AUC: 0.954; 95% CI, 0.915-0.994). The side-comparative V angle was greater for cases with complete DHT (8.7°; 95% CI, 7.9°-9.5°; n = 78) than for cases with partial DHT (4.8°; 95% CI, 3.3°-6.3°; n = 16) (p < 0.001). A cut-off value of 5° showed a sensitivity of 84.6% and a specificity of 66.7% (AUC 0.824; 95% CI, 0.725-0.924). CONCLUSION: The scapular-based V angle on anteroposterior radiographs distinguishes between Rockwood types III and V as well as cases with partial or complete DHT. STUDY DESIGN: Diagnostic study. LEVEL OF EVIDENCE: Level II.

Cost-Effectiveness Analysis of Treatment of Radial Head Subluxation.

PURPOSE: Radial head subluxation (RHS), also called nursemaid's elbow, is a common injury in young children treated by various health care providers. The diagnosis typically does not require radiographs, but they are often ordered in the emergency room. This study aimed to determine if there was a difference in the efficacy, cost, and amount of radiographs taken in RHS treatment according to the provider, specifically between orthopedic surgeons and pediatricians. METHODS: We reviewed the charts of 207 patients presenting with RHS in the emergency department (mean age of presentation = 2.1 years, range: 0.3 to 6.5 years) to determine the provider treating the condition, the number of attempts at reduction, the number of radiographs taken, the post-reduction management, and total hospital cost incurred. RESULTS: One hundred forty-four patients were treated by orthopedic surgeons, 51 by pediatricians, and 13 by residents. The mean number of radiographs obtained was 0.1, 0.8, and 0.5 for groups treated by an orthopedic surgeon, a pediatrician, and a resident, respectively (p = 0.04). The mean cost for reduction of an RHS was $114, $648, and $267 for groups treated by an orthopedic surgeon, a pediatrician, and a resident, respectively (p = 0.04) Conclusion: Although all three groups were effective in treating RHS, there was a significantly reduced hospital cost and a reduced need for radiographs when the provider was an orthopedic surgeon.

Assessment of influence of facemask treatment with skeletal anchorage on the temporomandibular joint using magnetic resonance imaging: a preliminary study.

OBJECTIVE: The aim of the study was to investigate the influence of facemask treatment with skeletal anchorage on the temporomandibular joint (TMJ) using magnetic resonance imaging (MRI), in patients with Class III malocclusion, accompanied by maxillary retrusion. METHODS: Fifteen patients with a mean age of 12.1±1.43 years were included in the study. All patients were treated using facemask with skeletal anchorage after eight weeks of Alternate Rapid Maxillary Expansion and Constriction (Alt-RAMEC) protocol. Magnetic resonance imaging was performed before and immediately after facemask treatment for TMJ evaluation. Disc position, condylar translation, degenerative changes of the condyles, and joint effusion were evaluated. To assess whether the alterations associated with the treatment were statistically significant, McNemar and marginal homogeneity tests were used. RESULTS: After facemask treatment, a statistically significant change was observed in the disc position (an anterior disc displacement with/without reduction in five TMJs) (p<0.05). The alteration in the condylar translation was not statistically significant (p>0.05). This treatment did not cause degenerative changes of the condyles or effusion in any of the TMJs. CONCLUSION: Facemask treatment with skeletal anchorage following the Alt-RAMEC protocol had a minimal influence on the TMJ, only by means of disc position, which was not negligible. Long-term results of such treatment are required for following up the changes observed in the TMJs.

Monteggia fracture associated with ipsilateral intercondylar distal humeral fracture with posterior interosseous nerve palsy: case report, medico-legal implications, and methodological assessment analysis.

BACKGROUND: The Monteggia fracture, defined as a fracture of the proximal third of the ulnar shaft associated with an anterior or posterior dislocation of the proximal radial epiphysis, is a serious injury accounting for 0.7% of all elbow fractures and dislocations in adults. For adult patients, good results can only be obtained through early diagnosis and adequate surgical treatment. Monteggia fracture-dislocations associated with distal humeral fracture are extremely rare injuries in adults and there are few cases described in the literature. Medico-legal implications arising from such conditions have a host of complexities that cannot be discounted. CASE REPORT: This case report revolves around a patient affected by a type I Monteggia fracture-dislocation, according to the Bado classification, associated with an ipsilateral intercondylar distal humeral fracture. To our knowledge, this combination of lesions has never been reported before in adult patients. A positive result was obtained due to early diagnosis, achievement of anatomical reduction, and optimal stabilization with internal fixation which made it possible to achieve early functional recovery. CONCLUSIONS: Monteggia fracture-dislocations associated with ipsilateral intercondylar distal humeral fracture are extremely rare in adults. In the case herein reported, a favorable outcome was obtained due to early diagnosis, achievement of anatomical reduction and management with internal fixation with plate and screws, as well as early functional training. Misdiagnosis makes such lesions risky in terms of potentially delayed treatment, increasing the need for surgical interventions and the possibility of high-risk complications and disabling sequelae, with possible medico-legal implications. In the case of unrecognized injuries under urgent circumstances, the injuries may become chronic, making the treatment more complex. The ultimate outcomes of a misdiagnosed Monteggia lesion can lead to very serious functional and aesthetic damage.

Clavicular hook plate versus dog-bone technique for acute high-grade acromioclavicular joint dislocation: a retrospective cohort study comparing clinical outcome scores, complications, and costs.

INTRODUCTION: Arthroscopically assisted coracoclavicular (CC) ligament fixation techniques have been promoted as providing superior outcomes for the treatment of acute high-grade acromioclavicular joint (ACJ) dislocations. Nevertheless, there is a lack of high-level evidence for clinically relevant benefits. At our institute, orthopaedic surgeons use an arthroscopically assisted coracoclavicular ligament fixation technique (DB), while general trauma surgeons use a clavicular hook plate (cHP) technique. The aim of the study was to compare clinical outcomes, complication rates, and costs between the two groups. MATERIALS AND METHODS: The hospital database was searched for patients treated for acute traumatic high-grade (Rockwood Typ ≥ III) ACJ dislocation using either a cHP or arthroscopically assisted DB technique between 2010 and 2019. Seventy-nine patients could be included (56 patients in the cHP group and 23 in the DB group). QuickDASH scores, subjective shoulder value (SSV) scores, pain scores (numerical pain rating scale 10), and complication rates were retrospectively collected through phone interviews and by screening patient charts as well as surgical reports. Costs per patient were obtained from the hospital's accounting system. RESULTS: Mean follow-up was 54 ± 33.7 and 45 ± 21.7 months in the cHP and DB group, respectively. QuickDASH and SSV scores did not differ, but patients in the cHP group reported significantly lower pain scores (p = 0.033). More patients reported hypertrophic or disturbing scars (p = 0.49) and sensibility disturbances (p = 0.007) in the cHP group. Three patients suffered from a frozen shoulder in the DB group (p = 0.023). CONCLUSION: Patient-reported outcomes are excellent after long-term follow-up for both techniques. There are no clinically relevant differences in clinical outcome scores based on our results and a review of the literature. Both techniques certainly have their benefits regarding secondary outcome measures. LEVEL OF CLINICAL EVIDENCE: Level 3, retrospective cohort study.

Cervical MRI assessment of traumatic anterior atlanto-occipital membrane complex injuries with evaluation of ancillary findings.

BACKGROUND AND PURPOSE: The purpose of this study was to identify and classify the different types of anterior atlanto-occipital membrane complex injuries on MRI and evaluate for the presence, size, and location of a prevertebral effusion on the preceding CT exams. MATERIALS AND METHODS: Patients who suffered an anterior atlanto-occipital membrane complex injury were identified retrospectively utilizing Nuance mPower software. An anatomic-based description of the location of the anterior atlanto-occipital membrane complex injury was recorded along with any additional osteoligamentous trauma of the craniocervical junction. The preceding cervical CT exams for these patients were reviewed for the presence and location of a prevertebral effusion. RESULTS: Fifty patients were identified with an acute, post-traumatic anterior atlanto-occipital membrane complex injury. Three distinct patterns of anterior atlanto-occipital membrane complex injury were observed. Nineteen patients demonstrated increased STIR signal with disruption of the anterior atlanto-occipital membrane, ten patients demonstrated increased STIR signal with disruption of the anterior atlanto-axial membrane, and twenty-one patients demonstrated increased STIR signal with disruption of both the anterior atlanto-occipital membrane and anterior atlanto-axial membrane. An effusion at the C1-C2 level was present in greater than 90% of patients with anterior atlanto-occipital membrane complex injury. CONCLUSIONS: The presence of a craniocervical prevertebral effusion on CT in trauma patients may raise suspicion for an injury to the anterior atlanto-occipital membrane complex and potentially trigger additional investigation with cervical MRI.

Effects of osseous structure based on three-dimensional reconstructive imaging evaluation in the assessment of temporomandibular joint disc position.

OBJECTIVES: This pilot morphological study aimed to investigate the association between anterior disc displacement (ADD) and the status of the mandibular condyle and articular fossa. MATERIALS AND METHODS: Thirty-four patients were divided into a normal articular disc position group and an ADD with and without reduction group. Images reconstructed were used to determine multiple group comparisons of these three different types of disc position, and the diagnostic efficacy for the morphological parameters with significant group difference was analyzed to assess. RESULTS: The condylar volume (CV), condylar superficial area (CSA), superior joint space (SJS), and medial joint space (MJS) all exhibited obvious changes (P < 0.05). Additionally, they all had a reliable diagnostic accuracy in differentiating between normal disc position and ADD with an AUC value from 0.723 to 0.858. Among them, the CV, SJS, and MJS (P < 0.05) had a significantly positive impact on the groups by analysis of multivariate logistic ordinal regression model. CONCLUSIONS: The CV, CSA, SJS, and MJS are significantly associated with different disc displacement types. The condyle in ADD exhibited altered dimensions. These could be promising biometric markers for assessing ADD. CLINICAL RELEVANCE: The morphological changes of mandibular condyle and glenoid fossa were significantly influenced by the status of disc displacement, and condyles with disc displacement had three-dimensionally altered condylar dimensions, irrespective of age and sex.

Assessment of ulnar nerve stability at the elbow by ultrasonography in children.

BACKGROUND: Elbow fractures are common in children. While Kirschner wire (K-wire) is the most commonly used fixation material in children, medial entry pins may be needed for fracture stability. This study aimed to assess ulnar nerve instability by ultrasonography in children. METHODS: We enrolled 466 children aged 2 months to 14 years between January 2019 and January 2020. There were at least 30 patients in each age group. Ulnar nerves were observed under the ultrasound equipment with the elbow fully extended and flexed. If ulnar nerves were subluxated or dislocated, they were considered to have ulnar nerve instability. The children's clinical data, including sex, age, and elbow sides, were analyzed. RESULTS: Of 466 enrolled children, 59 had ulnar nerve instability. Ulnar nerve instability rate was 12.7% (59/466). Instability was prevalent in children aged 0-2 years (P = .001). Among 59 children with ulnar nerve instability, 52.5% (31/59) had bilateral ulnar nerve instability, 16.9% (10/59) had right ulnar nerve instability, and 30.5% (18/59) had left ulnar nerve instability. Logistic analysis of the risk factors of ulnar nerve instability showed no significant difference in terms of sex and left or right ulnar nerve instability. CONCLUSIONS: Ulnar nerve instability correlated with age in children. Children aged <3 years had a low risk of ulnar nerve instability.

Understanding risk for early dislocation resulting in reoperation within 90 days of reverse total shoulder arthroplasty: extreme rare event detection through cost-sensitive machine learning.

BACKGROUND: Reliable prediction of postoperative dislocation after reverse total shoulder arthroplasty (RSA) would inform patient counseling as well as surgical and postoperative decision making. Understanding interactions between multiple risk factors is important to identify those patients most at risk of this rare but costly complication. To better understand these interactions, a game theory-based approach was undertaken to develop machine learning models capable of predicting dislocation-related 90-day readmission following RSA. MATERIAL & METHODS: A retrospective review of the Nationwide Readmissions Database was performed to identify patients who underwent RSA between 2016 and 2018 with a subsequent readmission for prosthetic dislocation. Of the 74,697 index procedures included in the data set, 740 (1%) experienced a dislocation resulting in hospital readmission within 90 days. Five machine learning algorithms were evaluated for their ability to predict dislocation leading to hospital readmission within 90 days of RSA. Shapley additive explanation (SHAP) values were calculated for the top-performing models to quantify the importance of features and understand variable interaction effects, with hierarchical clustering used to identify cohorts of patients with similar risk factor combinations. RESULTS: Of the 5 models evaluated, the extreme gradient boosting algorithm was the most reliable in predicting dislocation (C statistic = 0.71, F2 score = 0.07, recall = 0.84, Brier score = 0.21). SHAP value analysis revealed multifactorial explanations for dislocation risk, with presence of a preoperative humerus fracture; disposition involving discharge or transfer to a skilled nursing facility, intermediate care facility, or other nonroutine facility; and Medicaid as the expected primary payer resulting in strong, positive, and unidirectional effects on increasing dislocation risk. In contrast, factors such as comorbidity burden, index procedure complexity and duration, age, sex, and presence or absence of preoperative glenohumeral osteoarthritis displayed bidirectional influences on risk, indicating potential protective effects for these variables and opportunities for risk mitigation. Hierarchical clustering using SHAP values identified patients with similar risk factor combinations. CONCLUSION: Machine learning can reliably predict patients at risk for postoperative dislocation resulting in hospital readmission within 90 days of RSA. Although individual risk for dislocation varies significantly based on unique combinations of patient characteristics, SHAP analysis revealed a particularly at-risk cohort consisting of young, male patients with high comorbidity burdens who are indicated for RSA after a humerus fracture. These patients may require additional modifications in postoperative activity, physical therapy, and counseling on risk-reducing measures to prevent early dislocation after RSA.

Influence of kinematics of the lumbopelvic complex in hip arthroplasty dislocation: from assessment to recommendations.

INTRODUCTION: In total hip arthroplasty (THA), misplacement of the implant can provide instability. Adequate orientation of the acetabular cup is a challenge due to variations in inter-individual anatomy and kinematics of the pelvis in everyday life. The aim of this study was to characterize the kinematic factors influencing the risk of dislocation in order to give recommendations for optimal placement of the cup. We hypothesized that the lack of pelvic adaptation would influence the risk of prosthetic instability and motivate adapted. MATERIALS AND METHODS: Eighty patients with primary unilateral THA were included in a matched case-control study. Seventy-four patients were divided into two groups: group 1 (G1) consisting of patients with postoperative THA dislocation (37 patients) and group 2 (G2), without episodes of dislocation within two years postoperatively (37 patients). In both groups, spino-pelvic parameters and cup orientation were measured in standing and sitting positions with EOS® X-ray imaging and compared to each other between 12 and 24 months post-operatively. RESULTS: No significant difference between the two groups was found for static parameters. In a sitting position, a lack of pelvic retroversion with a significant lower variation in sacral slope was observed in group 1 (8.0° ± 9.3 for G1 versus 14.7° ± 6.2 for G2, p < 0.01). Twenty-two (59%) patients with THA instability had sacral slope variations of less than 10° versus eight (21% of patients) with stable THA (p < 0.01). Cup orientation in the Lewinnek safe zone was not significantly different (59% vs 67%, p = 0.62), and the spino-pelvic parameters and cup orientation measured did not change between the standing and sitting positions. However, only 14 (37%) cups in G1 were in the functional safe zone versus 24 (67%) in G2 (p = 0.03). CONCLUSION: Static parameters of the sagittal spinopelvic balance have a low predictive value for prosthetic instability. Dynamic analysis is essential. Kinematic parameters must be taken into account in determining the ideal position of the cup or stem. Stiffness with locked standing or sitting pelvis must be integrated in order to determine a personalized safe zone. LEVEL OF EVIDENCE: Level III (matched case-control study).

MRI as the optimal imaging modality for assessment and management of osteochondral fractures and loose bodies following traumatic patellar dislocation: a systematic review.

PURPOSE: To assess the imaging modalities used for diagnosis, as well as the management decisions of patients with osteochondral fractures (OCF) and loose bodies following traumatic patellar dislocation. METHODS: According to the Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA), MEDLINE, EMBASE, Web of Science, and PubMed were searched for results from January 1, 2000, to May 18, 2021, in two subsequent searches for English language studies that presented data on traumatic patellar dislocation. Quality of selected papers was assessed using the Methodological Index for Non-Randomised Studies (MINORS) and the Risk of Bias (RoB) 2.0 protocol. Results were qualitatively synthesised, and descriptive statistics were calculated. RESULTS: Forty studies totalling 3074 patients (1407 females) were included for the analysis. The mean age was 18.9 years (range 0-69). The population included 2446 first-time dislocations. The imaging modalities used were: 71.1% MRI, 52.6% plain radiography, 12.1% CT, and 0.68% ultrasound. In the 25 studies that reported the number of OCF, a total of 38.3% of patients were found to have OCF. 43.3% of patients with a first-time dislocation, and 34.7% of patients with previous dislocations, had at least one OCF. In the included paediatric studies (maximum age ≤ 18), the presence of OCF was detected by plain radiography in 10.1% of patients, MRI in 76.6% of patients, and CT in 89.5% of patients. For management of an OCF, the surgical options include fixation for larger pieces, excision for smaller pieces, and conservative management on a case-by-case basis. CONCLUSIONS: Based on the current available evidence, assessment and management of patellar dislocations and subsequent OCFs vary, with radiography and MRI as the main imaging modalities on presentation and particular benefit for MRI in the paediatric population. Findings from this study suggest the highest rate of OCF detection with MRI, and thus, surgeons should consider routinely ordering an MRI in patients with first-time patellar dislocation. Regarding management of OCFs, the main indication for fixation was large fragments, while smaller and poor-quality fragments are excised. Few studies choose conservative management of OCFs due to later requirements for surgical management. Future work should focus on large, high-quality studies, and implementation of randomised control trials to form guidelines for imaging patellar dislocations and management of OCFs. LEVEL OF EVIDENCE: Level IV.

Cross-sectional and longitudinal assessment of subchondral cysts in temporomandibular joints: Clinical and MRI study with a mean follow-up of 66 months.

PURPOSE: This observational study aimed to elucidate the pathophysiology of subchondral cysts (SC) in the temporomandibular joint (TMJ) and examine the results of conservative therapy administered to patients with SCs in the TMJ. METHODS: The study included 41 patients with SCs, extracted from 684 consecutive patients who underwent magnetic resonance imaging (MRI). The anatomical features of SCs and positional abnormalities of the articular disc were initially evaluated using MRI. A second MRI examination was performed for 28/41 patients at 40-107 months (mean, 66 months) after the first MRI. The joint space, anteroposterior width of the condylar head (WiC), articular eminence angle (AEA), and visual analog scale of jaw pain (VAS) were assessed alongside the MRI examinations. RESULTS: Most SCs were present in the anterosuperior and central condyle. Disc displacement was observed in 100% of 42 TMJs with SCs. Of the 29 joints in 28 patients, SCs in 19 joints resolved with time, whereas SCs in 10 joints persisted. A significant increase in the WiC and a significant decrease in AEA and VAS scores were observed on the second MRI scan. CONCLUSIONS: SCs tended to form in the anterosuperior and central parts of the condyle, where mechanical loading was likely to be applied. SCs are strongly associated with articular disc displacement. Two-thirds of SCs resolved over time, accompanied by resorption and osteophytic deformation of the condyle. SC might not be an indicator for the start of surgical treatment, and nonsurgical treatment could improve the clinical symptoms of patients with SCs.

Chopart Joint Injuries: Assessment, Treatment, and 10-Year Results.

OBJECTIVES: To investigate injury patterns and long-term outcomes of midtarsal (Chopart) injuries in a sizeable number of patients. DESIGN: Prospective study. SETTING: Level 1 trauma center. PATIENTS: One hundred twenty-two patients (average age 37.6 years) with 128 Chopart injuries over a 15-year period, 27% of who were polytraumatized. In 47%, more than 1 of the 4 bones of the midtarsal joint was fractured. The navicular and cuboid were fractured most often. Purely ligamentous dislocations occurred in 4%. INTERVENTIONS: Operative treatment tailored to the individual fracture pattern was performed in 91.4%. MAIN OUTCOME MEASUREMENTS: Foot Function Index, American Orthopaedic Foot and Ankle Society score, SF-36 physical (PCS) and mental component summary (MCS). RESULTS: Seventy-three patients with 75 Chopart injuries were available for follow-up at an average of 10.1 years. The Foot Function Index averaged 26.9, the American Orthopaedic Foot and Ankle Society score averaged 71.5, and the SF-36 PCS and MCS averaged 43.5 and 51.2, respectively. Negative prognostic factors were a high injury severity score, work-related accidents, open and multiple fractures, purely ligamentous dislocations, staged surgery, delay of treatment >4 weeks, postoperative infection, and primary or secondary fusion. Open reduction and internal fixation led to significantly better results than attempted closed reduction and percutaneous fixation. Radiographic signs of posttraumatic arthritis were observed in 93%, but only 4.7% of cases required a late fusion at the Chopart joint. CONCLUSIONS: Chopart joint injuries lead to functional restrictions in the long term. Purely ligamentous dislocations have the worst prognosis, whereas fractures of a single bone have a favorable outcome after anatomic reduction and internal fixation. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Using External Joint Stabilizer - Elbow (EJS-E) for treating elbow instability-biomechanical assessment and clinical outcomes.

BACKGROUND: This study aimed to evaluate the outcome of using an External Joint Stabilizer - Elbow (EJS-E) for persistent elbow instability based on biomechanical experiments and analysis of clinical results. METHODS: An EJS-E was used in 17 elbow instability patients. The median follow-up was 26 months (range, 12-42 months). We evaluated the flexion-extension and pronation-supination movement arcs, visual analog scale (VAS) score, Mayo Elbow Performance Score (MEPS), Broberg and Morrey classification system, and occurrence of complications in these patients. Moreover, construct stiffness and maximum strength tests were performed to evaluate the strength of the fixation techniques. RESULTS: The final median range of the extension-to-flexion and pronation-to-supination arc of the elbow was 135° (range, 110°-150°) and 165° (range, 125°-180°), respectively. The VAS pain scores were > 3 in two patients. The median MEPS was 90 (range, 80-100 points). Five patients showed signs of grade I post-traumatic osteoarthritis according to the Broberg and Morrey radiographic classification system, while grade II changes were observed in three patients. Complications included axis pin loosening with pin-tract infection in two patients, transient ulnar nerve symptoms in two patients, heterotopic ossification in two patients, and suture anchors infection in one patient. Based on the biomechanical testing results, the EJS-E exhibited higher stiffness and resisting force in varus loading. It was 0.5 (N/mm) stiffer and 1.8 (N·m) stronger than the internal joint stabilizer (IJS) by difference of medians (p < 0.05). CONCLUSIONS: Biomechanical and clinical outcomes show that EJS-E via the posterior approach can restore mobility and stability in all patients, thus serving as a valuable alternative option for the treatment of persistent instability of the elbow.