Faculty Bibliography

Symptomatic femoroacetabular impingement is one of the most common hip pathologies in young athletes. Intraoperative fluoroscopy is commonly used during hip arthroscopy to aid with portal placement and resection of the cam and pincer lesions. However, there are currently no universally agreed-on tools to allow for the assessment of adequacy of femoral and acetabular osteoplasty. Despite the general lack of consensus among hip arthroscopists, the senior author recommends using the femoroacetabular impingement resection arc to guide the adequacy of cam and pincer resection in hip arthroscopy. Using intraoperative fluoroscopy, one should aim to create a continuous "Shenton's line"-type arc along the inferior aspect of the anterior-inferior iliac spine and superolateral femoral neck base by resecting any bone that causes a break in the continuity of this arc.

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.

Calvarial abnormalities are usually discovered incidentally on radiologic studies or less commonly manifest with symptoms. This narrative review describes the imaging spectrum of the abnormal calvaria. The extent, multiplicity, and other imaging features of calvarial abnormalities can be combined with the clinical information to establish a final diagnosis or at least narrow the differential considerations. Prior trauma (congenital depression, leptomeningeal cysts, posttraumatic osteolysis), surgical intervention (flap osteonecrosis and burr holes), infection, and inflammatory processes (sarcoidosis) can result in focal bone loss, which may also be seen with idiopathic disorders without (bilateral parietal thinning and Gorham disease) or with (Parry-Romberg syndrome) atrophy of the overlying soft tissues. Anatomic variants (arachnoid granulations, venous lakes, parietal foramina) and certain congenital lesions (epidermoid and dermoid cysts, atretic encephalocele, sinus pericranii, and aplasia cutis congenita) manifest as solitary lytic lesions. Other congenital entities (lacunar skull and dysplasia) display a diffuse pattern of skull involvement. Several benign and malignant primary bone tumors involve the calvaria and manifest as lytic, sclerotic, mixed lytic and sclerotic, or thinning lesions, whereas multifocal disease is mainly due to hematologic or secondary malignancies. Metabolic disorders such as rickets, hyperparathyroidism, renal osteodystrophy, acromegaly, and Paget disease involve the calvaria in a more diffuse pattern. Online supplemental material is available for this article. ^©RSNA, 2021.

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.

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 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/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/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.

PURPOSE/OBJECTIVE:To assess the utility of a 2D dynamic HASTE sequence in assessment of cervical spine flexion-extension, specifically (1) comparing dynamic spondylolisthesis to radiographs and (2) assessing dynamic contact upon or deformity of the cord. METHODS:Patients with a dynamic flexion-extension sagittal 2D HASTE sequence in addition to routine cervical spine sequences were identified. Static and dynamic listhesis was first determined on flexion-extension radiographs reviewed in consensus. Blinded assessment of the dynamic HASTE sequence was independently performed by 2 radiologists for (1) listhesis and translation during flexion-extension and (2) dynamic spinal cord impingement (cord contact or deformity between neutral, flexion and extension). RESULTS:32 scans in 32 patients (9 males, 23 females) met inclusion criteria acquired on 1.5 T (n = 15) and 3 T (n = 17) scanners. The mean acquisition time was 51.8 s (range 20-95 seconds). Dynamic translation was seen in 14 patients on flexion-extension radiographs compared to 12 (reader 1) and 13 (reader 2) patients on HASTE, with 90.6 % agreement (K = 0.83; p = 0.789). In all cases dynamic listhesis was ≤3 mm translation with one patient showing dynamic listhesis in the range 4-6 mm. Four cases (13 %) demonstrated deformity of the cord between flexion-extension, not present in the neutral position. For cord impingement there was strong inter-reader agreement (K = 0.93) and the paired sample Wilcoxon signed rank test found no significant difference between the impingement scores of the two readers (p = 0.787). CONCLUSIONS:A sagittal dynamic flexion-extension HASTE sequence provides a rapid addition to standard MRI cervical spine protocols, which may useful for assessment of dynamic spondylolisthesis and cord deformity.

OBJECTIVES/OBJECTIVE:CT-guided radiofrequency ablation (CT-RFA) is considered to be the gold standard for treatment of osteoid osteoma (OO) yet treatment failures (TFs) continue to be reported. This systematic review was conducted to evaluate factors associated with TF, such as ablation time, lesion location, and patient age as well as evaluating how TF has trended over time. METHODS:Original studies reporting on patients undergoing CT-RFA of OO published between 2002 and 2019 were identified. TF was defined as patients with (1) recurrent or persistent pain +/- (2) imaging evidence of persistent OO. TFs were subdivided into those occurring after the index procedure (primary TF) or those occurring after repeat RFA (secondary TF). Subgroup analysis was performed for TF based on the study date (2002-2010 or 2010-2019), time duration of ablation at 90 °C (6 min or > 6 min), patient age, and tumor location (spinal vs. appendicular). RESULTS:Sixty-nine studies were included for a total of 3023 patients. The global primary TF rate was 8.3% whereas the secondary TF rate was 3.1%. The TF rate reported in studies published after 2011(7%) was about half that during the earlier time period 2002-2010 (14%). There was no statistical difference in TF corrected for age, OO location, or duration of ablation (respectively p = 0.39, 0.13, and 0.23). The global complication rate was 3%, the most frequent being skin burns (n = 24; 0.7%). CONCLUSIONS:A decrease in TF observed between 2011-2019 compared to 2002-2010 may reflect improvements in operator technique or advancements in equipment. Duration of ablation, patient age, or location of OO failed to significantly correlate with TF. KEY POINTS/CONCLUSIONS:• CT-guided radiofrequency ablation of osteoid osteomas is a safe technique with a low rate of treatment failure (8.3% failure rate after the primary radiofrequency reducing to 3.1% following a secondary treatment). • The treatment failure rate has decreased over time, possibly due to an improved understanding of the disease process, better technique, and advances in equipment. • Duration of ablation, patient age, or lesion location did not significantly correlate with treatment failure.