Faculty Bibliography

Purpose/UNASSIGNED:To explore the relationship between generalized joint hypermobility and hip labrum width. Methods/UNASSIGNED:and Fisher exact testing as well as linear regression. Results/UNASSIGNED: = .004). Conclusions/UNASSIGNED:Patients with a BTS ≥4 were found to have significantly thinner labra than those with a BTS of <4. Level of Evidence/UNASSIGNED:III, retrospective comparative trial.

PURPOSE/OBJECTIVE:To evaluate the association between postoperative cam lesion measured by the "femoroacetabular impingement resection (FAIR) arc" and 2-year patient outcomes following hip arthroscopy. METHODS:A retrospective review of prospectively gathered data from 2013-2017 was performed. All patients who underwent hip arthroscopy for FAI with ≥ 2-year follow-up were included. Cam FAIR arc measurements were made pre and postoperatively on a 45° Dunn view radiograph. The clinical effect of postoperative cam maximal radial distance (MRD) was assessed using the modified Harris Hip Score (mHHS) and Non-Arthritic Hip Score (NAHS). Patients were divided into subgroups based on relationship to the mean and standard deviations for cam MRD. One half standard deviation above the mean was found to be 3.15 mm. RESULTS:=0.004). Subgroup analysis demonstrated that patients in the cam MRD < 3.15 mm group had significantly higher mHHS (89.7 vs 70.0 p<0.001) and NAHS scores (90.5 vs 72.9, p<0.001) than those in the >3.15 mm group. Additionally, more patients in the <3.15 mm group reached the minimal clinically important difference (MCID) (95.2% vs 78.9%, p=0.048) and were above patient acceptable symptomatic state (PASS) (95.2% vs 52.6%, p<0.001) compared to the >3.15 mm group. CONCLUSION/CONCLUSIONS:Patients with a lower postoperative cam MRD relative to the FAIR arc demonstrated significantly improved outcomes as compared to those with higher postoperative MRD at two-year follow-up.

Purpose/UNASSIGNED:To train convolutional neural network (CNN) models to classify benign and malignant soft-tissue masses at US and to differentiate three commonly observed benign masses. Materials and Methods/UNASSIGNED:= 227) were used to train and evaluate a CNN model to distinguish malignant and benign lesions. Twenty percent of cases were withheld as a test dataset, and the remaining cases were used to train the model with a 75%-25% training-validation split and fourfold cross-validation. Performance of the model was compared with retrospective interpretation of the same dataset by two experienced musculoskeletal radiologists, blinded to clinical history. A second group of US images from 275 of the 419 patients containing the three common benign masses was used to train and evaluate a separate model to differentiate between the masses. The models were trained on the Keras machine learning platform (version 2.3.1), with a modified pretrained VGG16 network. Performance metrics of the model and of the radiologists were compared by using the McNemar test, and 95% CIs for performance metrics were estimated by using the Clopper-Pearson method (accuracy, recall, specificity, and precision) and the DeLong method (area under the receiver operating characteristic curve). Results/UNASSIGNED:The model trained to classify malignant and benign masses demonstrated an accuracy of 79% (95% CI: 68, 88) on the test data, with an area under the receiver operating characteristic curve of 0.91 (95% CI: 0.84, 0.98), matching the performance of two expert readers. Performance of the model distinguishing three benign masses was lower, with an accuracy of 71% (95% CI: 61, 80) on the test data. Conclusion/UNASSIGNED:The trained CNN was capable of differentiating between benign and malignant soft-tissue masses depicted on US images, with performance matching that of two experienced musculoskeletal radiologists.© RSNA, 2020.

BACKGROUND:The proximity of the posterior interosseous nerve (PIN) to the bicipital tuberosity is clinically important in the increasingly popular anterior single-incision technique for distal biceps tendon repair. Maximal forearm supination is recommended during tendon reinsertion from the anterior approach to ensure the maximum protective distance of the PIN from the bicipital tuberosity. PURPOSE:To compare the location of the PIN on magnetic resonance imaging (MRI) relative to bicortical drill pin instrumentation for suspensory button fixation via the anterior single-incision approach in varying positions of forearm rotation. STUDY DESIGN:Descriptive laboratory study. METHODS:Axial, non-fat suppressed, T1-weighted MRI scans of the elbow were obtained in positions of maximal supination, neutral, and maximal pronation in 13 skeletally mature individuals. Distances were measured from the PIN to (1) the simulated path of an entering guidewire (GWE-PIN) and (2) the cortical starting point of the guidewire on the bicipital tuberosity (CSP-PIN) achievable from the single-incision approach. To radiographically define the location of the nerve relative to constant landmarks, measurements were also made from the PIN to (3) the prominent-most point on the bicipital tuberosity (BTP-PIN) and (4) a perpendicular plane trajectory from the bicipital tuberosity exiting the opposing radial cortex (PPT-PIN). All measurements were subsequently compared between positions of pronation, neutral, and supination. In supination only, BTP-PIN and PPT-PIN measurements were made and compared at 3 sequential axial levels to evaluate the longitudinal course of the nerve relative to the bicipital tuberosity. RESULTS:< .001). CONCLUSION:This MRI study supports existing evidence that supination protects the PIN from the entering guidewire instrumentation during anterior, single-incision biceps tendon repair using cortical button fixation. The distances between the entering guidewire trajectory and PIN show that guidewire-inflicted injury to the nerve is unlikely during the anterior single-incision approach. CLINICAL RELEVANCE:When a safe technique is used, PIN injuries during anterior repair are likely the result of aberrant retractor placement, and we recommend against the use of retractors deep to the radial neck. Guidewire placement as close as possible to the anatomic footprint of the biceps tendon is safe from the anterior approach. MRI evaluation confirms that ulnar and proximal guidewire trajectory is the safest technique when using single-incision bicortical suspensory button fixation.

PURPOSE/OBJECTIVE:To determine if any association exists between physical examination and/or imaging findings [ultrasound (US) and magnetic resonance imaging (MRI)] and IPT in order to characterize the reliability of these diagnostic modalities. METHODS:Patients who had undergone US-guided iliopsoas tendon sheath injection (of lidocaine and a corticosteroid agent) as well as MRI performed within one year of injection between 2014-2019 were retrospectively reviewed. Demographic data, response to physical exam maneuvers, and response to injection were queried from patient records. US and MRIs were reviewed by 2 independent musculoskeletal-trained radiologists. Response to injection was considered positive if the patient improved by >2 points on a 0-10 VAS score. Chi-square and Fischer exact testing was utilized to assess for any associations. Sensitivities, specificities, positive predictive values, and negative predictive values were calculated. RESULTS:Sixty-three patients, with mean age 52.3 years +/- 17.3, with average BMI 27.4 +/- 4.3, and average follow-up was 33.6 months +/- 20.6 met inclusion criteria. No physical exam maneuvers, sonographic features, or MRI findings were significantly associated with response to iliopsoas tendon injection (p>0.05). Groin pain had a sensitivity of 100%, though a specificity of 7%. Snapping hip had a specificity of 82%, though a sensitivity of 24%. Pain with resisted SLR (sensitivity 62%, specificity 25%), and weakness with resisted SLR (sensitivity 15%, specificity 71%) both were non-reliable. Sonographic bursal distension and tendinosis had low sensitivities (67% and 63%, respectively) and specificities (35% and 32%, respectively). Bursal distension on MRI had sensitivity and specificity of 64% and 45% respectively. Tendon thickening had sensitivity and specificity of 55% and 60%, respectively, while heterogeneity had sensitivity and specificity of 52% and 65%, respectively. CONCLUSION/CONCLUSIONS:Neither physical examination, nor US, nor MRI findings were associated with a positive response to peritendinous iliopsoas corticosteroid injections in patients with suspected IPT.

OBJECTIVE:To determine whether the healing response in rotator cuff repairs can be quantitatively characterized using a multimodality imaging approach with MR signal intensity, power Doppler and shear wave elastography (SWE). MATERIALS AND METHODS/METHODS:Patients scheduled for rotator cuff repair were prospectively enrolled between September 2013 and June 2016. A 12 patient cohort with unilateral, full-thickness, supraspinatus tendon tears underwent MRI and ultrasound both preoperatively and postoperatively (at 3 and 6 months post-surgery). The MR signal intensity ratio of tendon-to-deltoid muscle (TMR), vascularity score by power Doppler (PD) and shear wave velocity (SWV) were measured. Repaired and asymptomatic control shoulders were compared over time and between modalities. RESULTS:TMR and vascularity of the tendon repair initially increased and then decreased postoperatively. Although not achieving statistical significance, postoperative SWV initially decreased and later increased, which negatively correlated with the TMR at 3 months (r = -0.73, p = 0.005). PD demonstrated a statistically significant change in tendon vascularity over time compared to the contralateral control (p = 0.009 at 3 months; p = 0.036 at 6 months). No significant correlation occurred between TMR and SWE at 6 months, or with PD at any time point. CONCLUSION/CONCLUSIONS:Despite a small patient cohort, this prospective pilot study suggests a temporal relationship of MRI and ultrasound parameters that parallels the expected phases of healing in the repaired rotator cuff.

OBJECTIVES/OBJECTIVE:To evaluate whether a follow-up magnetic resonance imaging (MRI) scan performed after initial ultrasound (US) to evaluate soft tissue mass (STM) lesions of the musculoskeletal system provides additional radiologic diagnostic information and alters clinical management. METHODS:A retrospective chart review was performed of patients undergoing initial US evaluations of STMs of the axial or appendicular skeleton between November 2012 and March 2019. Patients who underwent US examinations followed by MRI for the evaluation of STM lesions were identified. For inclusion, the subsequent pathologic correlation was required from either a surgical or image-guided biopsy. Imaging studies with pathologic correlations were then reviewed by 3 musculoskeletal radiologists, who were blinded to the pathologic diagnoses. The diagnostic utility of MRI was then assessed on the basis of a 5-point grading scale, and inter-reader agreements were determined by the Fleiss κ statistic. RESULTS:Ninety-two patients underwent MRI after US for STM evaluations. Final pathologic results were available in 42 cases. Samples were obtained by surgical excision or open biopsy (n = 34) or US-guided core biopsy (n = 8). The most common pathologic diagnoses were nerve sheath tumors (n = 9), lipomas (n = 5), and leiomyomas (n = 5). Imaging review showed that the subsequent MRI did not change the working diagnosis in 73% of cases, and the subsequent MRI was not considered to narrow the differential diagnosis in 68% of cases. There was slight inter-reader agreement for the diagnostic utility of MRI among individual cases (κ = 0.10) between the 3 readers. CONCLUSIONS:The recommendation of MRI to further evaluate STM lesions seen with US frequently fails to change the working diagnosis or provide significant diagnostic utility.

PURPOSE/OBJECTIVE:To determine the association between labral width as measured on preoperative MRI with hip-specific validated patient self-reported outcomes at a minimum of 2 years follow-up. METHODS:An IRB-approved retrospective review of prospectively gathered hip arthroscopy patients from 2010 to 2017 was performed. Inclusion criteria was defined as patients >18 years old with radiographic evidence of femoroacetabular impingement who underwent a primary labral repair and had a minimum of 2 years clinical follow-up. Exclusion criteria was defined as inadequate preoperative imaging, prior hip surgery, Tonnis grade ≥2 or lateral central edge angle <25 degrees. An a-priori power analysis was performed. MRI measurements of labral width were conducted by two blinded, musculoskeletal fellowship-trained radiologists at standardized "clockface" locations using a previously validated technique. Outcomes were assessed using the Harris Hip Score (HHS), Modified HHS (mHSS), and NonArthritic Hip Score (NAHS). For mHHS, a minimal clinically important difference (MCID) and Patient Acceptable Symptomatic State (PASS) of 8 and 74 were used, respectively. Patients were divided into groups by labral width of < (hypoplastic) and ≥ 1 standard deviation below the mean. Statistical analysis was performed using linear and polynomial regression, Mann-Whitney U, chi-square, Fischer exact, and interclass-correlation coefficients (ICC) testing. RESULTS:=0.26, p<0.001). CONCLUSION/CONCLUSIONS:Hip labral width < 1 standard deviation below the mean measured via preoperative MRI was associated with significantly worse functional outcomes following arthroscopic labral repair and treatment of FAI. The negative relationship between labral width and outcomes may be non-linear.

Purpose: Ultrasound is increasingly utilized as the first-line diagnostic evaluation of superficial soft tissue masses. With growing health care costs, there is increasing pressure to develop cost-effective methods to triage patients with palpable masses. Deep convolutional neural networks (CNNs) have demonstrated the ability to classify images with good accuracy. We hypothesize that using a limited dataset, a CNN can be trained to classify benign versus malignant soft tissue masses seen on ultrasound.
Material(s) and Method(s): Ultrasound exams from 227 patients were selected with up to two pairs of gray scale and Doppler images extracted per patient. Pairs of gray scale and Doppler images were concatenated to create a single image for a total of 344 combined images. Images from 49 patients (96 images) were withheld for a pathology enriched test set (56 benign and 40 malignant). The remaining 248 images were used to train a CNN using an 80/20 training-validation split with five-fold crossvalidation. The model was trained on Keras using a pretrained VGG-16 architecture on a Nvidia GTX 1070 GPU. The withheld test set was used for a reader study which consists of two experienced musculoskeletal radiologists to assess the performance of the model.
Result(s): The CNN achieved an average accuracy of 0.87+/-0.07 on fivefold cross validation. The best performing model in the five folds was selected for comparison against two musculoskeletal radiologists on the pathology enriched test data set. The model achieved an accuracy 0.73 on the test data set and an AUC of 0.78 which was comparable to the performance of the two musculoskeletal radiologists (0.76 and 0.65 accuracy).
Conclusion(s): Using a relatively small data set, a CNN can be trained to differentiate between benign and malignant soft tissue masses seen on ultrasound with its performance approaching that of two experienced musculoskeletal radiologists

Background/UNASSIGNED:Orthopedic surgeons use radiographs to determine degrees of fracture healing, guide progression of clinical care, and assist in determining weight bearing and removal of immobilization. However, no gold standard exists to determine the progression of healing of humeral shaft fractures treated non-operatively. Purpose/UNASSIGNED:The purpose of this study was to determine whether a scale comparable to the modified Radiographic Union Score for Tibial (RUST) fractures applied to non-operatively treated humeral shaft fractures can increase interobserver reliability in determining fracture healing. Methods/UNASSIGNED:A retrospective review was undertaken by three orthopedic traumatologists and one musculoskeletal radiologist, who evaluated 50 sets of anteroposterior and lateral radiographs, presented at random, of non-operatively treated humeral shaft fractures at various stages of healing from 17 patients. The radiographs were scored using a modified RUST scale called the Radiographic Humerus Union Measurement (RHUM). Observers were blinded to the time from injury. After a 4-week washout period, observers again scored the same radiographs. Observers classified each fracture as either healed or not healed based on the combination of radiographs. Inter- and intraobserver reliability of the RHUM were determined using an intraclass correlation coefficient (ICC). Interobserver reliability of determining a healed fracture was calculated using Cohen's kappa (κ) statistics. A receiver operator characteristic curve was conducted to determine the RHUM score predictive of a fracture being considered healed. Results/UNASSIGNED:ICC demonstrated almost perfect interobserver reliability (ICC, 0.838; ICC 95% CI, 0.765 to 0.896) and intraobserver reliability (ICC range, 0.822 to 0.948) of the RHUM. κ demonstrated substantial agreement between observers in considering a fracture healed (κ = 0.647). Receiver operating characteristic (ROC) curve demonstrated that a RHUM of 10 or higher is an excellent predictor of the observer considering the fracture healed (area under the ROC curve = 0.946, specificity = 0.957, 95% CI specificity, 0.916 to 0.979). Conclusions/UNASSIGNED:This cortical scoring system has excellent interobserver reliability in humeral shaft fractures treated non-operatively. Consistent with previous cortical scoring systems, a RHUM score of 10 or above can be considered radiographically healed.