Two-Year Results of Ceramic-on-Ceramic Hip Resurfacing in an International Multicenter Cohort.

INTRODUCTION: Hip resurfacing arthroplasty (HRA) is a bone-conserving alternative to total hip arthroplasty. We present the two-year clinical and radiographic follow-up of a novel ceramic-on-ceramic (CoC) HRA in an international multicenter cohort. METHODS: Patients undergoing HRA between September 2018 and January 2021 were prospectively included. Patient-reported outcome measures (PROMS) in the form of the Forgotten Joint Score (FJS), Hip Disability and Osteoarthritis Outcome Score (HOOS) Jr., Western Ontario and McMaster Universities Arthritis Index (WOMAC), Oxford Hip Score (OHS), and University of California, Los Angeles (UCLA) Activity Score were collected preoperatively, and at 1- and 2-years post-operation. Serial radiographs were assessed for migration, component alignment, evidence of osteolysis or loosening, and heterotopic ossification formation. RESULTS: The study identified 200 patients who reached a minimum 2-year follow-up (mean 3.5 years). Of these, 185 completed PROMS follow-up at 2 years. There was a significant improvement in HOOS (P < 0.001) and OHS (P < 0.001) between the pre-operative, 1-year, and 2-year outcomes. Patients also reported improved pain (P < 0.001), function (P < 0.001), and reduced stiffness (P < 0.001) as measured by the WOMAC score. Patients had improved activity scores on the UCLA Active Score (P < 0.001), with 45% reporting a return to impact activity at 2 years. At 1 and 2 years, the FJS was not significantly different (P = 0.38). There was no migration, osteolysis, or loosening of any of the implants. The mean acetabular cup inclination angle was 41.3 degrees, and the femoral component shaft angle was 137 degrees. No fractures were reported over the 2-year follow-up, with only 1 patient reporting a sciatic nerve palsy. There were 2 revisions, one for unexplained pain at 3 months due to acetabular component malposition and one at 33.5 months for acetabular implant failure. CONCLUSION: The CoC resurfacing at 2 years post-operation demonstrates promising results with satisfactory outcomes in all recorded PROMS. Further long-term data is needed to support the widespread adoption of this prosthesis as an alternative to other HRA bearings.

Advances in Imaging for Pre-Surgical Planning in Hip Resurfacing Arthroplasty.

BACKGROUND: Accurate pre-operative templating is essential for the success of hip resurfacing arthroplasty (HRA). While digital radiograph is currently considered the gold standard, stereoradiograph and CT converted 3D methods have shown promising results. However, there is no consensus in the literature regarding the preferred modality for HRA templating, and angular measurements are often overlooked. Thus, this study aimed to: 1) compare the performances of different modality in implant sizing and angle measurements, 2) evaluate the measurement reproducibility, 3) assess the impact of severe osteoarthritis on femoral head sizing, and 4) based on the analysis above, explore the optimal imaging and planning strategy for HRA. HYPOTHESIS: An optimal imaging modality exists for HRA planning regarding implant sizing and angular measurements. MATERIALS AND METHODS: Pre-operative imaging data from seventy-seven HRA surgeries were collected. Three raters performed templating using digital radiograph, stereoradiograph, and CT converted 3D models. Measurements for femoral head size, neck-shaft angle, and calcar-shaft angle were obtained. The femoral head sizing was compared to the intraoperative clinical decision. The reproducibility of measurements was assessed using the Intraclass Correlation Coefficient (ICC). Correlations were examined between sizing disagreement and osteoarthritis grade (Tonnis Classification). RESULTS: Digital radiograph, stereoradiograph, and 3D techniques predicted one size off target in 27/77 (35%), 49/70 (70%), and 75/77 (97%) of cases, respectively, corresponding to 1.8±1.6 (0 to 5.67), 0.9±0.7 (0 to 2.67), and 0.4±0.4 (0 to 1.67) sizes off target, indicating statistically significant differences among all three modalities, with p-values all below 0.01. There were no statistically significant differences among the different modalities for angular measurements. Measurements showed moderate to excellent reproducibility (ICC = 0.628-0.955). High grade osteoarthritis did not impact image sizing in any modality (r = 0.08-0.22, all p>0.05). DISCUSSION: CT converted 3D models were more accurate for implant sizing in HRA, but did not significantly outperform other modalities in angular measurements. Given the high costs and increased radiation exposure associated with CT, the study recommended using CT scans selectively, particularly for precise femoral head sizing, while alternative imaging methods can be effectively used for angular measurements. LEVEL OF EVIDENCE: III; Retrospective comparative diagnostic study.

Determination of preoperative risk factors for iliopsoas tendonitis after total hip arthroplasty: A simulation study.

This study aims to identify preoperative risk factors for iliopsoas tendonitis after total hip arthroplasty, a complication typically attributed to acetabular cup position and orientation, using a validated iliopsoas impingement detection simulation. Analyzing CT scans and X-rays of 448 patients using a validated preoperative planning protocol, patients were simulated for iliopsoas impingement and categorized into at-risk and not at-risk groups based on a prior validation study, with a 23% at-risk incidence. Implementing a propensity score matching algorithm to reduce covariate imbalance, we identified factors that may exacerbate risk of iliopsoas tendonitis. Parameters that were investigated included standing pelvic tilt, functional femoral rotation, and the difference between the planned acetabular cup diameter and native femoral head diameter (ΔC-NFH). Comparing pelvic tilt, we found a significant difference between the groups (at-risk: -6.0°, not at-risk: -0.7°; p << 0.01). A similar trend was noted for ΔC-NFH (at-risk: +5.7 mm, not at-risk: +5.1 mm; p = 0.01). Additional simulations of at-risk patients indicated increased anteversion of the acetabular cup reduces impingement risk more effectively than medialisation. These findings suggest that spinopelvic parameters may exacerbate iliopsoas irritation risk, underscoring their importance in preoperative planning and patient expectation management. Similar findings of a greater than 6 mm difference between cup size and native femoral head diameter being a significant risk for iliopsoas tendonitis have been observed before, underscoring its potential veracity. These results may provide surgeons with a simple threshold that can be used in determining a cup size to reduce the risk of iliopsoas tendonitis.

Inadequate Annotation and Its Impact on Pelvic Tilt Measurement in Clinical Practice.

BACKGROUND: Accurate pre-surgical templating of the pelvic tilt (PT) angle is essential for hip and spine surgeries, yet the reliability of PT annotations is often compromised by human error, inherent subjectivity, and variations in radiographic quality. This study aims to identify challenges leading to inadequate annotations at a landmark dimension and evaluating their impact on PT. METHODS: We retrospectively collected 115 consecutive sagittal radiographs for the measurement of PT based on two definitions: the anterior pelvic plane and a line connecting the femoral head's centre to the sacral plate's midpoint. Five annotators engaged in the measurement, followed by a secondary review to assess the adequacy of the annotations across all the annotators. RESULTS: The outcomes indicated that over 60% images had at least one landmark considered inadequate by the majority of the reviewers, with poor image quality, outliers, and unrecognized anomalies being the primary causes. Such inadequacies led to discrepancies in the PT measurements, ranging from -2° to 2°. CONCLUSION: This study highlights that landmarks annotated from clear anatomical references were more reliable than those estimated. It also underscores the prevalence of suboptimal annotations in PT measurements, which extends beyond the scope of traditional statistical analysis and could result in significant deviations in individual cases, potentially impacting clinical outcomes.

Comparison of iliopsoas tendonitis after hip resurfacing arthroplasty and total hip arthroplasty: A case-controlled investigation using a validated simulation.

Iliopsoas tendonitis, typically caused by impingement with the acetabular cup, occurs in up to 18% of patients after total hip arthroplasty (THA) and up to 30% of patients after hip resurfacing arthroplasty (HRA). We have developed a simulation for detecting iliopsoas impingement and validated it in a previous study of THA patients. However, due to the difference in incidence between HRA and THA, this study had two aims. First, to validate the simulation in a cohort of HRA patients and, second, to comparethe results of the HRA and THA patients to understand any differences in their etiology. We conducted a retrospective search in an experienced surgeon's database for HRA patients with iliopsoas tendonitisand control patients without iliopsoas tendonitis, resulting in two cohorts of 12 patients. Using CT scans, 3D models of the each patient's prosthetic and bony anatomy were generated, landmarked, and simulated. Regarding validation of the simulation for HRA patients, impingement significantly predicted the probability of iliopsoas tendonitis in logistic regression models and the simulation had a sensitivity of 83%, specificity of 100%, and an AUC ROC curve of 0.95. Unexpectedly, the HRA cohort exhibited less impingement than the THA cohort. Our novel simulation has now been demonstrated to detect iliopsoas impingement and differentiate between the symptomatic and asymptomatic cohorts in investigations of THA and HRA patients. This tool has the potential to be used preoperatively, to guide decisions about optimal cup placement, and postoperatively, to assist in the diagnosis of iliopsoas tendonitis.

Utility of a 2D kinematic HASTE sequence in magnetic resonance imaging assessment of adjacent segment degeneration following anterior cervical discectomy and fusion.

OBJECTIVES: To evaluate a dynamic half-Fourier acquired single turbo spin echo (HASTE) sequence following anterior cervical discectomy and fusion (ACDF) at the junctional level for adjacent segment degeneration comparing dynamic listhesis to radiographs and assessing dynamic cord contact and deformity during flexion-extension METHODS: Patients with ACDF referred for cervical spine MRI underwent a kinematic flexion-extension sagittal 2D HASTE sequence in addition to routine sequences. Images were independently reviewed by three radiologists for static/dynamic listhesis, and compared to flexion-extension radiographs. Blinded assessment of the HASTE sequence was performed for cord contact/deformity between neutral, flexion, and extension, to evaluate concordance between readers and inter-modality agreement. Inter-reader agreement for dynamic listhesis and impingement grade and inter-modality agreement for dynamic listhesis on MRI and radiographs was assessed using the kappa coefficient and percentage concordance. RESULTS: A total of 28 patients, mean age 60.2 years, were included. Mean HASTE acquisition time was 42 s. 14.3% demonstrated high grade dynamic stenosis (> grade 4) at the adjacent segment. There was substantial agreement for dynamic cord impingement with 70.2% concordance (kappa = 0.62). Concordance across readers for dynamic listhesis using HASTE was 81.0% (68/84) (kappa = 0.16) compared with 71.4% (60/84) (kappa = 0.40) for radiographs. Inter-modality agreement between flexion-extension radiographs and MRI assessment for dynamic listhesis across the readers was moderate (kappa = 0.41; 95% confidence interval: 0.16 to 0.67). CONCLUSIONS: A sagittal flexion-extension HASTE cine sequence provides substantial agreement between readers for dynamic cord deformity and moderate agreement between radiographs and MRI for dynamic listhesis. CLINICAL RELEVANCE STATEMENT: Degeneration of the adjacent segment with instability and myelopathy is one of the most common causes of pain and neurological deterioration requiring re-operation following cervical fusion surgery. KEY POINTS: • A real-time kinematic 2D sagittal HASTE flexion-extension sequence can be used to assess for dynamic listhesis, cervical cord, contact and deformity. • The additional kinematic cine sequence was well tolerated and the mean acquisition time for the 2D HASTE sequence was 42 s (range 31-44 s). • A sagittal flexion-extension HASTE cine sequence provides substantial agreement between readers for dynamic cord deformity and moderate agreement between radiographs and MRI for dynamic listhesis.

Evaluating Pelvic Tilt Using the Pelvic Antero-Posterior Projection Images: A Systematic Review.

BACKGROUND: Pelvic tilt (PT) is a routinely evaluated parameter in hip and spine surgeries, and is usually measured on a sagittal pelvic radiograph. This may not always be feasible due to limitations such as landmark visibility, pelvic anomaly, and hardware presence. Tremendous efforts have been dedicated to using pelvic antero-posterior (AP) radiographs for assessing sagittal PT. Thus, this systematic review aimed to collect these methods and evaluate their performances. METHODS: Two independent reviewers searched the PubMed, Ovid, Cochrane, and Web of Science databases in June 2023 with backward reference trailing (Google Scholar archive). There were 30 studies recruited. Risk of bias was assessed using the prediction model risk of bias assessment tool. The relevant data were tabulated in a standardized form for evaluating either the absolute PT or relative PT. Disagreement was resolved by discussing with the senior author. RESULTS: There were 19 parameters from pelvic AP projection images involved, with 4 studies which used artificial intelligence, eyeball, or statistical shape method not involving a specific parameter. In comparing the PT values from pelvic sagittal images with those extrapolated from antero-posterior projection images, the highest correlation coefficient was found to be 0.91. The mean absolute difference (error) was 2.6°, with a maximum error reaching 10.9°. Most studies supported the feasibility of using AP parameters to calculate changes in PT. CONCLUSIONS: No individual AP parameter was found to precisely estimate absolute PT. However, relative PT can be derived by evaluating serial AP radiographs of a patient in varying postures, employing any AP parameters.

Tips and tricks in ultrasound-guided musculoskeletal interventional procedures.

Ultrasound visualization affords proceduralists versatile and accurate guidance for a variety of percutaneous, minimally invasive procedures in the musculoskeletal system including joint (intra-articular) injections or aspirations, intra-bursal injections, peritendinous, and perineural injections. A variety of percutaneous procedures are traditionally performed blindly, but may be more easily or more accurately performed with the real-time assistance of ultrasound guidance. Other procedures are only possible utilizing image-guidance, due to the required precision of the injection because of delicate local anatomy or depth of the injection; ultrasound is a safe, portable, and widespread modality that can be used to assist the proceduralist in localizing the needle tip in such cases, to ensure safe and accurate delivery of the medication, most frequently a solution of steroid and anesthetic. This review aims to provide a foundational approach to ultrasound-guided procedures in the musculoskeletal system, offering tips and tricks that can be employed in many different procedures including intra-articular, juxta-articular, and perineural injections for a multitude of clinical scenarios. Technical considerations regarding ultrasound transducer selection, sonographic technique, as well as common indications, contraindications, and complications of these procedures, are presented. Additionally, a variety of pharmacologic considerations for proceduralists contemplating ultrasound-guided injections are discussed.

Quadriceps tendon malalignment is an independent anatomical deformity which is the primary abnormality associated with lateral facet patellofemoral joint osteoarthritis.

PURPOSE: The purposes of this study are to, firstly, develop techniques to accurately identify extensor mechanism malalignment by measuring the alignment of the quadriceps tendon (QTA) with computerized tomography (CT) scans. Secondly, to investigate correlations between QTA and lower limb bony anatomical variations within a representative normal population. Lastly, to evaluate the clinical significance of QTA by establishing its potential connection with lateral facet patellofemoral joint osteoarthritis (LFPFJOA). METHOD: CT scans were orientated to a mechanical axis reference frame and three techniques developed to measure the alignment of the quadriceps tendon. Multiple measurement of bony alignment from the hip to the ankle were performed on each scan. A series of 110 cadaveric CT scans were measured to determine normal values, reproducibility, and correlations with bony anatomy. Secondly, a comparison between 2 groups of 25 patients, 1 group with LFPFJOA and 1 group with isolated medial OA and no LFPFJOA. RESULTS: From the cadaveric study, it was determined that the alignment of the quadriceps tendon is on average 4.3° (SD 3.9) varus and the apex of the tendon is 9.1 mm (SD 7.7 mm) lateral to the trochlear groove and externally rotated 1.9° (SD 12.4°) from the centre of the femoral shaft. There was no association between the quadriceps tendon alignment and any other bony measurements including tibial tubercle trochlear groove distance (TTTG), coronal alignment, trochlear groove alignment and femoral neck anteversion. A lateralized QTA was significantly associated with LFPFJOA. QTA in the LFPFJOA group was 9.6° varus (SD 2.8°), 21.3 mm (SD 6.6) lateralised and 17.3° ER (SD 11°) compared to 5.5° (SD 2.3°), 10.7 mm (SD 4.9) and 3.3° (SD 7.2°), respectively, in the control group (p < 0.001). A significant association with LFPFJOA was also found for TTTG (17.2 mm (SD 5.7) vs 12.1 mm (SD 4.3), p < 0.01). Logistic regression analysis confirmed the QTA as having the stronger association with LFPFJOA than TTTG (AUC 0.87 to 0.92 for QTA vs 0.79 for TTTG). CONCLUSION: These studies have confirmed the ability to accurately determine QTA on CT scans. The normal values indicate that the QTA is highly variable and unrelated to bony anatomy. The comparative study has determined that QTA is clinically relevant and a lateralised QTA is the dominant predictor of severe LFPFJOA. This deformity should be considered when assessing patella maltracking associated with patella osteoarthritis, patella instability and arthroplasty. LEVEL OF EVIDENCE: III (retrospective cohort study).

Effect of Aspirin vs Enoxaparin on 90-Day Mortality in Patients Undergoing Hip or Knee Arthroplasty: A Secondary Analysis of the CRISTAL Cluster Randomized Trial.

Importance: Ischemic heart disease remains the leading cause of mortality following hip and knee arthroplasty. Due to its antiplatelet and cardioprotective properties, aspirin has been proposed as an agent that could reduce mortality when used as venous thromboembolism (VTE) prophylaxis following these procedures. Objective: To compare aspirin with enoxaparin in reducing 90-day mortality for patients undergoing hip or knee arthroplasty procedures. Design, Setting, and Participants: This study was a planned secondary analysis of the CRISTAL cluster randomized, crossover, registry-nested trial performed across 31 participating hospitals in Australia between April 20, 2019, and December 18, 2020. The aim of the CRISTAL trial was to determine whether aspirin was noninferior to enoxaparin in preventing symptomatic VTE following hip or knee arthroplasty. The primary study restricted the analysis to patients undergoing total hip or knee arthroplasty for a diagnosis of osteoarthritis only. This study includes all adult patients (aged ≥18 years) undergoing any hip or knee arthroplasty procedure at participating sites during the course of the trial. Data were analyzed from June 1 to September 6, 2021. Interventions: Hospitals were randomized to administer all patients oral aspirin (100 mg daily) or subcutaneous enoxaparin (40 mg daily) for 35 days after hip arthroplasty and 14 days after knee arthroplasty procedures. Main Outcomes and Measures: The primary outcome was mortality within 90 days. The between-group difference in mortality was estimated using cluster summary methods. Results: A total of 23 458 patients from 31 hospitals were included, with 14 156 patients allocated to aspirin (median [IQR] age, 69 [62-77] years; 7984 [56.4%] female) and 9302 patients allocated to enoxaparin (median [IQR] age, 70 [62-77] years; 5277 [56.7%] female). The mortality rate within 90 days of surgery was 1.67% in the aspirin group and 1.53% in the enoxaparin group (estimated difference, 0.04%; 95% CI, -0.05%-0.42%). For the subgroup of 21 148 patients with a nonfracture diagnosis, the mortality rate was 0.49% in the aspirin group and 0.41% in the enoxaparin group (estimated difference, 0.05%; 95% CI, -0.67% to 0.76%). Conclusions and Relevance: In this secondary analysis of a cluster randomized trial comparing aspirin with enoxaparin following hip or knee arthroplasty, there was no significant between-group difference in mortality within 90 days when either drug was used for VTE prophylaxis. Trial Registration: http://anzctr.org.au Identifier: ACTRN12618001879257.

Accuracy of acetabular component alignment with surgical guidance systems during hip arthroplasty.

BACKGROUND: Navigation in total hip arthroplasty has been shown to improve acetabular positioning and can decrease the incidence of mal-positioned acetabular components. This study aimed to assess two surgical guidance systems by comparing intra-operative measurements of acetabular component inclination and anteversion with a post-operative CT scan. METHODS: We prospectively collected intra-operative navigation data from 102 hips receiving conventional THA or hip resurfacing arthroplasty through either a direct anterior or posterior approach. Two guidance systems were used simultaneously: an inertial navigation system (INS) and an optical navigation system (ONS). Acetabular component anteversion and inclination were measured on a post-operative CT. RESULTS: The average age of the patients was 64 years (range: 24-92) and the average BMI was 27 kg/m2 (range 19-38). 52% had hip surgery through an anterior approach. 98% of the INS measurements and 88% of the ONS measurements were within 10° of the CT measurements. The mean (and standard deviation) of the absolute difference between the postoperative CT and the intra-operative measurements for inclination and anteversion were 3.0° (2.8) and 4.5° (3.2) respectively for the ONS, along with 2.1° (2.3) and 2.4° (2.1) respectively for the INS. There was a significantly lower mean absolute difference to CT for the INS when compared to ONS in both anteversions (p < 0.001) and inclination (p = 0.02). CONCLUSIONS: We found that both inertial and optical navigation systems allowed for adequate acetabular positioning as measured on postoperative CT, and thus provide reliable intraoperative feedback for optimal acetabular component placement. LEVEL OF EVIDENCE: Therapeutic Level II.

Correlations Analysis of Different Pelvic Tilt Definitions: A Preliminary Study.

Background: Pelvic tilt (PT) is described as the pelvic orientation along the transverse axis, yet 4 PT definitions were established based on radiographic landmarks: anterior pelvic plane (PTa), the center of femoral heads to sacral plate (PTm), pelvic outlet (PTh), and sacral slope (SS). These landmarks quantify a similar concept, yet understanding of their relationships is lacking, and their differences are sometimes ignored. Purpose: This study aimed to examine the correlations and differences of PT definitions for education and research purposes. Methods: This study reviewed 105 sagittal pelvic radiographs of patients (68 men and 37 women) awaiting hip surgery at a single clinic. Hip hardware and spine pathologies were examined for subgroup analysis. Two observers annotated 4 PTs in a gender-dependent manner and repeated it after 6 months. The linear regression model and intraclass correlation coefficient (ICC) were applied with a 95% confidence interval. Results: The SS showed no correlation to the other 3 PT definitions, except for females in the hip hardware subgroup (n = 17). PTm demonstrated very strong linear correlation to PTh (r > 0.9) under the linear model PTm = 0.951 × PTh - 68.284. Conclusion: The PTm and PTh can be calculated from each other under a simple linear regression equation, which enables comparisons between them. SS presented poor correlations to the other PT parameters, except for the female subgroup with hip implant that required further analysis; PTa-related comparisons showed high anatomical variations between patients.

The Sacro-femoral-pubic Angle Is Unreliable to Estimate Pelvic Tilt: A Meta-analysis.

BACKGROUND: The accurate measurement of pelvic tilt is critical in hip and spine surgery. A sagittal pelvic radiograph is most often used to measure pelvic tilt, but this radiograph is not always routinely obtained and does not always allow the measurement of pelvic tilt because of problems with image quality or patient characteristics (such as high BMI or the presence of a spinal deformity). Although a number of recent studies have explored the correlation between pelvic tilt and the sacro-femoral-pubic angle using AP radiographs (SFP method), which aimed to estimate pelvic tilt without a sagittal radiograph, disagreement remains about whether the SFP method is sufficiently valid and reproducible for clinical use. QUESTIONS/PURPOSES: The purpose of this meta-analysis was to evaluate the correlation between SFP and pelvic tilt in the following groups: (1) overall cohort, (2) male and female cohort, and (3) skeletally mature and immature cohorts (young and adult groups, defined as patients older or younger than 20 years). Additionally, we assessed (4) the errors of SFP-estimated pelvic tilt angles and determined (5) measurement reproducibility using the intraclass correlation coefficient. METHODS: This meta-analysis was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and registered in PROSPERO (record ID: CRD42022315673). PubMed, Embase, Cochrane, and Web of Science were screened in July 2022. The following keywords were used: sacral femoral pubic, sacro femoral pubic, or SFP. The exclusion criteria were nonresearch articles such as commentaries or letters and studies that only investigated relative pelvic tilt rather than absolute pelvic tilt. Although the included studies had different patient recruitment strategies, study quality-wise, they all used an adequate amount of radiographs for landmark annotation and applied a correlation analysis for the relationship between the SFP angle and pelvic tilt. Thus, no risk of bias was found. Participant differences were mitigated via subgroup and sensitivity analyses to remove outliers. Publication bias was assessed using the p value of a two-tailed Egger regression test for the asymmetry of funnel plots, as well as the Duval and Tweedie trim and fill method for potential missing publications to impute true correlations. The extracted correlation coefficients r were pooled using the Fisher Z transformation with a significance level of 0.05. Nine studies were included in the meta-analysis, totaling 1247 patients. Four studies were used in the sex-controlled subgroup analysis (312 male and 460 female patients), and all nine studies were included in the age-controlled subgroup analysis (627 adults and 620 young patients). Moreover, a sex-controlled subgroup analysis was conducted in two studies with only young cohorts (190 young male patients and 220 young female patients). RESULTS: The overall pooled correlation coefficient between SFP and pelvic tilt was 0.61, with high interstudy heterogeneity (I 2 = 76%); a correlation coefficient of 0.61 is too low for most clinical applications. The subgroup analysis showed that the female group had a higher correlation coefficient than the male group did (0.72 versus 0.65; p = 0.03), and the adult group had a higher correlation coefficient than the young group (0.70 versus 0.56; p < 0.01). Three studies reported erroneous information about the measured pelvic tilt and calculated pelvic tilt from the SFP angle. The mean absolute error was 4.6° ± 4.5°; in one study, 78% of patients (39 of 50) were within 5° of error, and in another study, the median absolute error was 5.8º, with the highest error at 28.8° (50 female Asian patients). The intrarater intraclass correlation coefficients ranged between 0.87 and 0.97 for the SFP angle and between 0.89 and 0.92 for the pelvic tilt angle, and the interrater intraclass correlation coefficients ranged between 0.84 and 1.00 for the SFP angle and 0.76 and 0.98 for the pelvic tilt angle. However, large confidence intervals were identified, suggesting considerable uncertainty in measurement at the individual radiograph level. CONCLUSION: This meta-analysis of the best-available evidence on this topic found the SFP method to be unreliable to extrapolate sagittal pelvic tilt in any patient group, and it was especially unreliable in the young male group (defined as patients younger than age 20 years). Correlation coefficients generally were too low for clinical use, but we remind readers that even a high correlation coefficient does not alone justify clinical application of a metric such as this, unless further subgroup analyses find low error and low heterogeneity, which was not the case here. Further ethnicity-segregated subgroup analyses with age, sex, and diagnosis controls could be useful in the future to determine whether there are some subgroups in which the SFP method is useful. LEVEL OF EVIDENCE: Level III, diagnostic study.

Deep Learning Diagnosis and Classification of Rotator Cuff Tears on Shoulder MRI.

BACKGROUND: Detection of rotator cuff tears, a common cause of shoulder disability, can be time-consuming and subject to reader variability. Deep learning (DL) has the potential to increase radiologist accuracy and consistency. PURPOSE: The aim of this study was to develop a prototype DL model for detection and classification of rotator cuff tears on shoulder magnetic resonance imaging into no tear, partial-thickness tear, or full-thickness tear. MATERIALS AND METHODS: This Health Insurance Portability and Accountability Act-compliant, institutional review board-approved study included a total of 11,925 noncontrast shoulder magnetic resonance imaging scans from 2 institutions, with 11,405 for development and 520 dedicated for final testing. A DL ensemble algorithm was developed that used 4 series as input from each examination: fluid-sensitive sequences in 3 planes and a sagittal oblique T1-weighted sequence. Radiology reports served as ground truth for training with categories of no tear, partial tear, or full-thickness tear. A multireader study was conducted for the test set ground truth, which was determined by the majority vote of 3 readers per case. The ensemble comprised 4 parallel 3D ResNet50 convolutional neural network architectures trained via transfer learning and then adapted to the targeted domain. The final tear-type prediction was determined as the class with the highest probability, after averaging the class probabilities of the 4 individual models. RESULTS: The AUC overall for supraspinatus, infraspinatus, and subscapularis tendon tears was 0.93, 0.89, and 0.90, respectively. The model performed best for full-thickness supraspinatus, infraspinatus, and subscapularis tears with AUCs of 0.98, 0.99, and 0.95, respectively. Multisequence input demonstrated higher AUCs than single-sequence input for infraspinatus and subscapularis tendon tears, whereas coronal oblique fluid-sensitive and multisequence input showed similar AUCs for supraspinatus tendon tears. Model accuracy for tear types and overall accuracy were similar to that of the clinical readers. CONCLUSIONS: Deep learning diagnosis of rotator cuff tears is feasible with excellent diagnostic performance, particularly for full-thickness tears, with model accuracy similar to subspecialty-trained musculoskeletal radiologists.

Deep Learning Reconstruction Enables Prospectively Accelerated Clinical Knee MRI.

Background MRI is a powerful diagnostic tool with a long acquisition time. Recently, deep learning (DL) methods have provided accelerated high-quality image reconstructions from undersampled data, but it is unclear if DL image reconstruction can be reliably translated to everyday clinical practice. Purpose To determine the diagnostic equivalence of prospectively accelerated DL-reconstructed knee MRI compared with conventional accelerated MRI for evaluating internal derangement of the knee in a clinical setting. Materials and Methods A DL reconstruction model was trained with images from 298 clinical 3-T knee examinations. In a prospective analysis, patients clinically referred for knee MRI underwent a conventional accelerated knee MRI protocol at 3 T followed by an accelerated DL protocol between January 2020 and February 2021. The equivalence of the DL reconstruction of the images relative to the conventional images for the detection of an abnormality was assessed in terms of interchangeability. Each examination was reviewed by six musculoskeletal radiologists. Analyses pertaining to the detection of meniscal or ligament tears and bone marrow or cartilage abnormalities were based on four-point ordinal scores for the likelihood of an abnormality. Additionally, the protocols were compared with use of four-point ordinal scores for each aspect of image quality: overall image quality, presence of artifacts, sharpness, and signal-to-noise ratio. Results A total of 170 participants (mean age ± SD, 45 years ± 16; 76 men) were evaluated. The DL-reconstructed images were determined to be of diagnostic equivalence with the conventional images for detection of abnormalities. The overall image quality score, averaged over six readers, was significantly better (P < .001) for the DL than for the conventional images. Conclusion In a clinical setting, deep learning reconstruction enabled a nearly twofold reduction in scan time for a knee MRI and was diagnostically equivalent with the conventional protocol. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Roemer in this issue.

Iliopsoas tendonitis after total hip arthroplasty : an improved detection method with applications to preoperative planning.

AIMS: Iliopsoas impingement occurs in 4% to 30% of patients after undergoing total hip arthroplasty (THA). Despite a relatively high incidence, there are few attempts at modelling impingement between the iliopsoas and acetabular component, and no attempts at modelling this in a representative cohort of subjects. The purpose of this study was to develop a novel computational model for quantifying the impingement between the iliopsoas and acetabular component and validate its utility in a case-controlled investigation. METHODS: This was a retrospective cohort study of patients who underwent THA surgery that included 23 symptomatic patients diagnosed with iliopsoas tendonitis, and 23 patients not diagnosed with iliopsoas tendonitis. All patients received postoperative CT imaging, postoperative standing radiography, and had minimum six months' follow-up. 3D models of each patient's prosthetic and bony anatomy were generated, landmarked, and simulated in a novel iliopsoas impingement detection model in supine and standing pelvic positions. Logistic regression models were implemented to determine if the probability of pain could be significantly predicted. Receiver operating characteristic curves were generated to determine the model's sensitivity, specificity, and area under the curve (AUC). RESULTS: Highly significant differences between the symptomatic and asymptomatic cohorts were observed for iliopsoas impingement. Logistic regression models determined that the impingement values significantly predicted the probability of groin pain. The simulation had a sensitivity of 74%, specificity of 100%, and an AUC of 0.86. CONCLUSION: We developed a computational model that can quantify iliopsoas impingement and verified its accuracy in a case-controlled investigation. This tool has the potential to be used preoperatively, to guide decisions about optimal cup placement, and postoperatively, to assist in the diagnosis of iliopsoas tendonitis.Cite this article: Bone Jt Open 2023;4(1):3-12.

Imaging features and biopsy yield of soft tissue metastatic lesions: 10-year single tertiary center experience.

OBJECTIVE: To evaluate imaging features of soft tissue metastases, technical factors associated with diagnostic yield of image-guided biopsy, and clinical impact of biopsy results on patient outcomes. MATERIALS AND METHODS: A total of 1605 image-guided soft tissue biopsies were retrospectively identified from December 2010 to December 2020. Included lesions were histologically proven musculoskeletal soft tissue metastases. Lesions were excluded if intraabdominal, intrathoracic, retroperitoneal, associated with osseous lesions or surgical scar implants or arising from skin or lymph nodes. Image guidance modality, needle size, number of cores, and lesion location, size, and depth from skin were recorded. Patient demographics, malignancy history, biopsy-driven changes in management, and survival rate after biopsy were collected. RESULTS: Forty-six patients met the inclusion criteria with a biopsy diagnostic yield of 44/46 (95.7%). Metastases were most commonly located truncal (82.6%, p < 0.001) and intramuscular (78.3%, p < 0.001). A total of 37/46 (80.4%) biopsies were US-guided. And 9/46 (19.6%) were CT-guided. There was no significant difference in the number of cores or mean needle gauge between diagnostic and nondiagnostic biopsies. At time of review, 23 (50%) patients were deceased, with a mean survival of 13.5 months after biopsy. The majority (71.7%) of patients had a known primary malignancy at time of biopsy, most commonly lung (24.2%) and breast (24.2%). Overall survival showed no association with anatomic location (p > 0.83) or tissue type (p > 0.34). The most common biopsy-driven outcome was initiation of chemotherapy, immunotherapy, and/or radiotherapy (52.2%). CONCLUSION: Image-guided biopsy for soft tissue metastases has high diagnostic yield and commonly influences clinical management. Metastases were most commonly intramuscular in the trunk and are associated with poor prognosis.

Effect of Aspirin vs Enoxaparin on Symptomatic Venous Thromboembolism in Patients Undergoing Hip or Knee Arthroplasty: The CRISTAL Randomized Trial.

Importance: There remains a lack of randomized trials investigating aspirin monotherapy for symptomatic venous thromboembolism (VTE) prophylaxis following total hip arthroplasty (THA) or total knee arthroplasty (TKA). Objective: To determine whether aspirin was noninferior to enoxaparin in preventing symptomatic VTE after THA or TKA. Design, Setting, and Participants: Cluster-randomized, crossover, registry-nested trial across 31 hospitals in Australia. Clusters were hospitals performing greater than 250 THA or TKA procedures annually. Patients (aged ≥18 years) undergoing hip or knee arthroplasty procedures were enrolled at each hospital. Patients receiving preoperative anticoagulation or who had a medical contraindication to either study drug were excluded. A total of 9711 eligible patients were enrolled (5675 in the aspirin group and 4036 in the enoxaparin group) between April 20, 2019, and December 18, 2020. Final follow-up occurred on August 14, 2021. Interventions: Hospitals were randomized to administer aspirin (100 mg/d) or enoxaparin (40 mg/d) for 35 days after THA and for 14 days after TKA. Crossover occurred after the patient enrollment target had been met for the first group. All 31 hospitals were initially randomized and 16 crossed over prior to trial cessation. Main Outcomes and Measures: The primary outcome was symptomatic VTE within 90 days, including pulmonary embolism and deep venous thrombosis (DVT) (above or below the knee). The noninferiority margin was 1%. Six secondary outcomes are reported, including death and major bleeding within 90 days. Analyses were performed by randomization group. Results: Enrollment was stopped after an interim analysis determined the stopping rule was met, with 9711 patients (median age, 68 years; 56.8% female) of the prespecified 15 562 enrolled (62%). Of these, 9203 (95%) completed the trial. Within 90 days of surgery, symptomatic VTE occurred in 256 patients, including pulmonary embolism (79 cases), above-knee DVT (18 cases), and below-knee DVT (174 cases). The symptomatic VTE rate in the aspirin group was 3.45% and in the enoxaparin group was 1.82% (estimated difference, 1.97%; 95% CI, 0.54%-3.41%). This failed to meet the criterion for noninferiority for aspirin and was significantly superior for enoxaparin (P = .007). Of 6 secondary outcomes, none were significantly better in the enoxaparin group compared with the aspirin group. Conclusions and Relevance: Among patients undergoing hip or knee arthroplasty for osteoarthritis, aspirin compared with enoxaparin resulted in a significantly higher rate of symptomatic VTE within 90 days, defined as below- or above-knee DVT or pulmonary embolism. These findings may be informed by a cost-effectiveness analysis. Trial Registration: ANZCTR Identifier: ACTRN12618001879257.

Improving Acetabular Component Positioning in Total Hip Arthroplasty: A Cadaveric Study of an Inertial Navigation Tool and a Novel Registration Method.

Background: Incorrect acetabular component positioning in total hip arthroplasty (THA) has been associated with poor outcomes. Computer-assisted hip arthroplasty increases accuracy and consistency of cup positioning compared to conventional methods. Traditional navigation units have been associated with problems such as bulkiness of equipment and reproducibility of anatomical landmarks, particularly in obese patients or the lateral position. Purpose: We sought to evaluate the accuracy of a novel miniature inertial measurement system, the Navbit Sprint navigation device (Navbit, Sydney, Australia), to navigate acetabular component positioning in both the supine and lateral decubitus positions. We also aimed to validate a new method of patient registration that does not require acquisition of anatomical landmarks for navigation. Methods: We performed THA in a cadaveric study in supine and lateral positions using Navbit navigation to record cup position and compared mean scores from 3 Navbit devices for each cup position on post-implantation CT scans. Results: A total of 11 cups (5 supine and 6 lateral) were available for comparison. A difference of 2.34° in the supine direct anterior approach when assessing acetabular version was deemed to be statistically but not clinically significant. There was no statistically significant difference between CT and navigation measurements of cup position in the lateral position. Conclusion: This cadaveric study suggests that a novel inertial-based navigation tool is accurate for cup positioning in THA in the supine and lateral positions. Furthermore, it validates a novel registration method that does not require the identification of anatomical landmarks.