Iatrogenic "overshoot" nerve injuries: imaging features.

OBJECTIVE: Describe features of iatrogenic "overshoot" nerve injuries on ultrasound and MRI, which occur when an instrument passes through the bone and injures the nerve after it penetrates the opposite cortex. MATERIALS AND METHODS: After a keyword search of the radiology database at a tertiary care orthopedic hospital from January 2016 to December 2022, those fulfilling the inclusion criteria of (1) instrumentation through the bone during surgery, (2) acute neuropathy immediately after surgery, (3) nerve injury confirmed on electrodiagnostics, and (4) imaging consistent with overshoot nerve injury were included. Imaging studies were retrospectively evaluated to determine primary and secondary signs of an overshoot nerve injury. RESULTS: Six patients (3 females, mean age 26.7 (range 10-49) years) had nerve injury fitting the mechanism of injury: 3 injuries to the radial nerve during fixation of distal humerus fractures, 1 tibial nerve and 1 superficial peroneal nerve injury during fixation of tibial fractures, and 1 posterior interosseous nerve injury during biceps tendon repair. Ultrasounds were performed in all while 4 also had MRI. Secondary signs included (1) cortical defect adjacent to injured nerve (n=2); (2) scar extending from bone to injured nerve (n=2); (3) screw tip pointing to injured nerve (n=1, 4) tract in bone on MRI from previous instrumentation pointing to injured nerve (n=2). CONCLUSION: In addition to primary signs such as laceration or neuroma, secondary signs of "overshoot" nerve injury include cortical defect, scar extending to nerve, screw tip pointing to nerve, and linear tract in the bone on MRI.

Differences in imaging and clinical characteristics are associated with higher rates of decompression-fusion versus decompression-alone in women compared to men for lumbar degenerative spondylolisthesis.

PURPOSE: The goals were to ascertain if differences in imaging/clinical characteristics between women and men were associated with differences in fusion for lumbar degenerative spondylolisthesis. METHODS: Patients had preoperative standing radiographs, CT scans, and intraoperative fluoroscopic images. Symptoms and comorbidity were obtained from patients; procedure (fusion-surgery or decompression-alone) was obtained from intraoperative records. With fusion surgery as the dependent variable, men and women were compared in multivariable logistic regression models with clinical/imaging characteristics as independent variables. The sample was dichotomized, and analyses were repeated with separate models for men and women. RESULTS: For 380 patients (mean age 67, 61% women), women had greater translation, listhesis angle, lordosis, and pelvic incidence, and less diastasis and disc height (all p ≤ 0.03). The rate of fusion was higher for women (78% vs. 65%; OR 1.9, p = 0.008). Clinical/imaging variables were associated with fusion in separate models for men and women. Among women, in the final multivariable model, less comorbidity (OR 0.5, p = 0.05), greater diastasis (OR 1.6, p = 0.03), and less anterior disc height (OR 0.8, p = 0.0007) were associated with fusion. Among men, in the final multivariable model, opioid use (OR 4.1, p = 0.02), greater translation (OR 1.4, p = 0.0003), and greater diastasis (OR 2.4, p = 0.0002) were associated with fusion. CONCLUSIONS: There were differences in imaging characteristics between men and women, and women were more likely to undergo fusion. Differences in fusion within groups indicate that decisions for fusion were based on composite assessments of clinical and imaging characteristics that varied between men and women.

Dynamic ultrasound assessment of hip instability and anterior and posterior hip impingement.

OBJECTIVE: In this technical report, we describe our protocol for the dynamic sonographic evaluation of the hip and assess reliability of the ultrasound assessment of hip microinstability. MATERIALS AND METHODS: Our clinical experience with a standardized dynamic ultrasound of the hip performed in a series of 27 patients with imaging performed by an experienced musculoskeletal radiologist during physical examination by an orthopedic surgeon specializing in hip preservation is illustrated with clinical photographs and ultrasound images from volunteers and selected patients. Interrater reliability for the diagnosis of microinstability was calculated. RESULTS: Dynamic ultrasound technique and findings of hip instability, femoroacetabular impingement, and ischiofemoral impingement with corresponding clinical photos showing the necessary physical examination maneuvers are described. Interrater agreement for the diagnosis of microinstability was substantial (κ 0.606 [0.221-0.991]). CONCLUSION: At our institution, dynamic ultrasound of the hip during physical examination complements information gathered from static imaging by providing real-time correlation of symptoms with what is occurring anatomically.

Communication-related experiences of individuals in the early phase of semantic dementia and their families: an interview study.

BACKGROUND: Semantic dementia (SD), a subtype of frontotemporal dementia, manifests as verbal symptoms, including social and behavioural deficits, associated with focal atrophy of the frontotemporal lobes. This study aimed to clarify the experiences of individuals with early-onset SD receiving speech and language rehabilitation (hereafter referred to as 'rehabilitation'), with the intent of making it routine, as well as the experiences of their families. METHODS: Individual interviews were conducted with nine families with members who had adopted rehabilitation. Verbatim transcripts were used as data, and analyzed inductively according to the content analysis process. RESULTS: The family members realised the changes in the personality and behaviour of the individual with SD early, to the extent that they thought the individual with SD was different from before and were distressed by the loss of verbal communication. Nevertheless, the family members found a way to communicate by maintaining residual functions through rehabilitation and utilising their unique relationship with the individual with SD. CONCLUSIONS: It is important to carefully explain the characteristics of the disease and the long-term significance of rehabilitation to individuals with SD and their families in the early stages of the disease.

Diagnostic Performance of MRI for Component Loosening in Total Knee Arthroplasty Compared with Radiography.

Background Because loosening of total knee arthroplasty (TKA) occurs due to poor osseous integration at component-bone interfaces, interface assessment may be helpful in diagnosing loosening at MRI. Purpose To determine interreader reproducibility for characterizing component interfaces and diagnosing loosening and to evaluate the diagnostic performance of MRI for diagnosing loosening after TKA compared with radiography. Materials and Methods Consecutive knees with TKA that underwent revision between July 2018 and June 2019 and were imaged at MRI and radiography were included in this retrospective study. Interface type (normal, fibrous membrane, fluid, or osteolysis), percent integration (<33%, 33%-66%, or >66%), and presence of bone marrow edema pattern were assessed. Loosening was diagnosed at MRI if no or almost no normal interface was present. Sensitivity and specificity were compared with radiographs by using surgical findings as reference. Gwet agreement coefficient evaluated interreader reproducibility between two readers and multivariable logistic regression assessed risk factors for loosening. Results Among 116 knees in 114 patients (mean age, 63 years ± 10 [SD]; 59 women), 61 of 116 knees (52.6%) had at least one loose component. Interreader reproducibility of MRI was substantial to excellent (Gwet agreement coefficient, 0.67-0.96). Loosening was associated with fluid interface (odds ratio [OR], 20.1; 95% CI: 5.7, 70.9) or osteolysis (OR, 3.1; 95% CI: 1.8, 5.3), absence of any normal interface (OR, 11.8; 95% CI: 6.3, 22.2), poor (<33%) osseous integration (OR, 20.4; 95% CI: 9.7, 42.6), and bone marrow edema pattern (OR, 4.7; 95% CI: 2.8, 7.8). Sensitivity and specificity of MRI for loosening were 84% (27 of 32; 95% CI: 72, 97) and 85% (71 of 84; 95% CI: 77, 92) for the patellar, 31% (eight of 26; 95% CI: 13, 49) and 100% (90 of 90; 95% CI: 100, 100) for the femoral, and 81% (22 of 27; 95% CI: 66, 96) and 98% (87 of 89; 95% CI: 95, 100) for the tibial component, respectively. MRI had higher sensitivity (84% vs 31%; P < .001) but lower specificity (85% vs 96%; P = .003) for patellar component loosening than did radiography, respectively, whereas no evidence of a difference was found for femoral (sensitivity and specificity, MRI vs radiography: 31% vs 46% [P = .20] and 100% vs 99% [P > .99], respectively) or tibial (sensitivity and specificity, MRI vs radiography: 81% vs 70% [P = .16] and 98% vs 97% [P = .32], respectively) component loosening. Conclusion MRI demonstrated substantial to excellent interreader reproducibility and higher sensitivity than did radiography for diagnosing patellar component loosening after total knee arthroplasty. © RSNA, 2022 Online supplemental material is available for this article.

Evaluation of deep learning reconstructed high-resolution 3D lumbar spine MRI.

OBJECTIVES: To compare interobserver agreement and image quality of 3D T2-weighted fast spin echo (T2w-FSE) L-spine MRI images processed with a deep learning reconstruction (DLRecon) against standard-of-care (SOC) reconstruction, as well as against 2D T2w-FSE images. The hypothesis was that DLRecon 3D T2w-FSE would afford improved image quality and similar interobserver agreement compared to both SOC 3D and 2D T2w-FSE. METHODS: Under IRB approval, patients who underwent routine 3-T lumbar spine (L-spine) MRI from August 17 to September 17, 2020, with both isotropic 3D and 2D T2w-FSE sequences, were retrospectively included. A DLRecon algorithm, with denoising and sharpening properties was applied to SOC 3D k-space to generate 3D DLRecon images. Four musculoskeletal radiologists blinded to reconstruction status evaluated randomized images for motion artifact, image quality, central/foraminal stenosis, disc degeneration, annular fissure, disc herniation, and presence of facet joint cysts. Inter-rater agreement for each graded variable was evaluated using Conger's kappa (κ). RESULTS: Thirty-five patients (mean age 58 ± 19, 26 female) were evaluated. 3D DLRecon demonstrated statistically significant higher median image quality score (2.0/2) when compared to SOC 3D (1.0/2, p < 0.001), 2D axial (1.0/2, p < 0.001), and 2D sagittal sequences (1.0/2, p value < 0.001). κ ranges (and 95% CI) for foraminal stenosis were 0.55-0.76 (0.32-0.86) for 3D DLRecon, 0.56-0.73 (0.35-0.84) for SOC 3D, and 0.58-0.71 (0.33-0.84) for 2D. Mean κ (and 95% CI) for central stenosis at L4-5 were 0.98 (0.96-0.99), 0.97 (0.95-0.99), and 0.98 (0.96-0.99) for 3D DLRecon, 3D SOC and 2D, respectively. CONCLUSIONS: DLRecon 3D T2w-FSE L-spine MRI demonstrated higher image quality and similar interobserver agreement for graded variables of interest when compared to 3D SOC and 2D imaging. KEY POINTS: • 3D DLRecon T2w-FSE isotropic lumbar spine MRI provides improved image quality when compared to 2D MRI, with similar interobserver agreement for clinical evaluation of pathology. • 3D DLRecon images demonstrated better image quality score (2.0/2) when compared to standard-of-care (SOC) 3D (1.0/2), p value < 0.001; 2D axial (1.0/2), p value < 0.001; and 2D sagittal sequences (1.0/2), p value < 0.001. • Interobserver agreement for major variables of interest was similar among all sequences and reconstruction types. For foraminal stenosis, κ ranged from 0.55 to 0.76 (95% CI 0.32-0.86) for 3D DLRecon, 0.56-0.73 (95% CI 0.35-0.84) for standard-of-care (SOC) 3D, and 0.58-0.71 (95% CI 0.33-0.84) for 2D.

Diagnostic ultrasound of tendon injuries in the setting of distal radius fractures.

OBJECTIVE: Describe tendon injuries and their structural causes seen on ultrasound in wrists with distal radius fractures and estimate the accuracy of ultrasound and its impact on clinical management. MATERIALS AND METHODS: Ultrasounds of 226 wrists (221 patients) with distal radius fractures were retrospectively reviewed. Ultrasound findings of tendon injuries and their structural causes were correlated with surgery and clinical outcome. Accuracy and inter- and intra-observer reproducibilities were calculated. RESULTS: Twenty-five wrists were treated non-operatively while 201 underwent surgery. Ultrasound demonstrated hardware contact with flexor pollicis longus (FPL) in 76 wrists, extensor pollicis longus (EPL) in 21, and other tendons in 94. Ultrasound identified tendon ruptures in 23 wrists (13 EPL/8 FPL/2 extensor indicis proprius (EIP)), most of which were surgically confirmed. Among 12 wrists with confirmed EPL ruptures, distal radius fracture had been treated with volar plating in 6 and non-operatively in 6, and ultrasound showed osseous irregularity at the rupture site in 8. All FPL ruptures occurred in wrists with volar plating. Ultrasound findings were concordant with subsequent clinical management in most. In 2, ultrasound findings led to the decision to remove hardware despite lack of symptoms. Ultrasound had sensitivity/specificity/accuracy of 88/99/98% for identifying a specific tendon as ruptured and 88/87/88% for tendon abnormalities in general. Inter- and intra-observer reproducibilities were excellent (kappa = 0.85 ~ 1.0). CONCLUSION: Certain wrist tendons, particularly EPL and FPL, are vulnerable after distal radius fractures. Ultrasound is accurate and useful for detecting tendon injury and sources of tendon irritation and can guide clinical management.

Experiences of families of people living with frontotemporal dementia: a qualitative systematic review.

Frontotemporal dementia (FTD) is characterised by atrophy of the frontal and/or temporal lobes. People with FTD show language and emotional disturbances from onset, and communication problems usually affect people with FTD and their families even before diagnosis. These unique characteristics of FTD are not well understood and create substantial problems for people living with FTD and their families. This review explores the experiences of families of people living with FTD. Studies were selected and screened according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched four bibliographic databases for articles up to February 2021 to identify qualitative data on the experiences of families. The Critical Appraisal Skills Programme checklist for qualitative studies was used to assess all included studies. Of 235 identified articles, we included six studies in the qualitative synthesis. Meta-ethnography was conducted to interpret families' experiences of people living with FTD. The emergent concepts were synthesised into five themes: Something is wrong with my loved one; No one fully understands; Existential pain of caring for a loved one with FTD; Increased burden owing to specific FTD symptoms; and Forced to adapt to new and unique ways of living with a loved one with FTD. This review highlighted families' confusion and suffering (which began in the early stages of the disease, and sometimes before diagnosis) and the difficulty of communicating with people with FTD. These findings have implications for future practice, as they demonstrate the positive effect on family life of appropriate support that is provided early, rather than after the disease has progressed.

MRI Visualization of Polyethylene Post Fractures in Posterior Stabilized Total Knee Arthroplasty.

Polyethylene post fracture is a recognized complication of posterior stabilized total knee arthroplasty. Two radiologists retrospectively reviewed MRI examinations of 19 reported post fractures in 18 patients; all fractures were subsequently confirmed surgically with no false-positive cases. All post fractures were visualized as a combination of post deformity and signal-void fragment in a joint recess. A metal artifact reduction 3D multispectral imaging sequence improved fracture visualization versus conventional sequences in 47% of cases.

Ultrasound features of traumatic digital nerve injuries of the hand with surgical confirmation.

OBJECTIVE: Characterize the appearance of digital nerve injuries in different ultrasound planes and correlate the presence and size of neuromas with time from injury. MATERIALS AND METHODS: Surgically confirmed nerve injuries were retrospectively evaluated. Appearances of the nerve injury in the available imaging planes were reviewed by two readers. Associations between presence and size of neuroma with time from injury were analyzed. RESULTS: Injuries of 29 digital nerves (3 incomplete lacerations, 17 complete lacerations, 6 with 7 stump neuromas, 3 neuromas-in-continuity) noted on ultrasound were surgically confirmed. Among the 20 lacerations, long-axis images were obtained in 15, of which 10 depicted the injury and 4 did not. Among the 10 depicting the injury in long axis, 2 showed a discrete gap, and 7 showed the nerve obscured by laceration tissue without a gap. In short axis, the nerve injury was visible in all 20, and nerve laceration was seen as a discrete gap in 2, and obscuration by laceration tissue in 14. Neuromas were hypoechoic and well-defined. There was a positive association between time and presence of neuroma (OR = 1.3, p = 0.002). Correlations between time and cross-sectional area (rs = 0.45) and volume (rs = 0.57) of neuromas were moderately positive. CONCLUSION: Ultrasound long axis may be less useful, and those short axis may be more reliable for assessing digital nerve injuries than previously reported. Neuromas are hypoechoic and well-defined, and their size can vary based on time from injury.

MRI of the ulnar nerve pre- and post-transposition: imaging features and rater agreement.

OBJECTIVE: Determine the rater agreement of MRI features of the ulnar nerve pre- and post-transposition and association with recurrent symptoms. MATERIALS AND METHODS: This IRB-approved retrospective cohort analysis examined 23 subjects who underwent elbow MRI pre- and post-ulnar nerve transposition from 1999 to 2018, 10 of whom developed recurrent symptoms. Pre- and post-transposition MRIs were evaluated by two blinded radiologists for ulnar nerve cross-sectional area, signal intensity, fascicular architecture, caliber change, and perineural scar. Inter-rater agreement was estimated using intraclass correlation coefficients (ICCs) for continuous variables and Gwet's agreement coefficient (AC) for categorical variables. Binary logistic regression modeling probed associations between imaging markers and symptom recurrence. RESULTS: The ulnar nerve, post-operatively, demonstrated statistically significant increases in size (p < 0.001), signal intensity (p = 0.021), and abrupt caliber change (p = 0.024). None of the imaging features, except for higher signal intensity of the nerve pre-transposition as demonstrated by one rater, were predictive of symptom recurrence. Inter-rater agreement for cross-sectional area measurements of the ulnar nerve at the cubital tunnel was excellent (ICCs of 0.91 and 0.83). Substantial-to-excellent inter-rater agreement was observed pre-operatively for nerve signal intensity, caliber change, and fascicular architecture. Post-operatively, agreement on nerve signal intensity and perineural scar was excellent (ACs of 0.90 and 0.88), but only slight for caliber change (0.15). CONCLUSION: Inter-rater agreement for qualitative and quantitative assessment of the ulnar nerve was generally robust. Post-transposition, the ulnar nerve was generally larger and more T2-hyperintense, but MRI features were not predictive of recurrent ulnar neuropathy, except for perhaps the signal intensity of the nerve pre-transposition.

Ultrasound of the distal biceps brachii tendon using four approaches: reproducibility and reader preference.

OBJECTIVES: To determine which sonographic appearance of the distal biceps brachii tendon (DBBT) is preferred by readers, and if images obtained by two different operators are reproducible. METHODS: We performed an IRB-approved prospective sonographic evaluation of the DBBT in 50 healthy elbows using four different approaches (anterior, lateral, medial, posterior) performed by two operators. Five musculoskeletal radiologists independently reviewed the images, and ranked the four approaches based on overall appearance of echogenicity of the tendon, visualized length, and visualization of the insertion. RESULTS: The medial approach was preferred in 79.6% of elbows, anterior in 17.6%, lateral in 2.8%, and the posterior approach was never preferred. The difference was statistically significant (P < 0.001). Kappa values for the five readers were 0.61 to 0.8 for choosing the images produced by the medial approach. CONCLUSION: The appearance of the DBBT using the medial approach is preferred by readers and is reproducible between different operators.

Denoising of diffusion MRI improves peripheral nerve conspicuity and reproducibility.

BACKGROUND: Quantitative diffusion MRI is a promising technique for evaluating peripheral nerve integrity but low signal-to-noise ratio (SNR) can impede measurement accuracy. PURPOSE: To evaluate principal component analysis (PCA) and generalized spherical deconvolution (genSD) denoising techniques to improve within-subject reproducibility and peripheral nerve conspicuity. STUDY TYPE: Prospective. SUBJECTS: Seven healthy volunteers and three peripheral neuropathy patients. FIELD STRENGTH/SEQUENCE: 3T/multiband single-shot echo planar diffusion sequence using multishell 55-direction scheme. ASSESSMENT: Images were processed using four methods: "original" (no denoising), "average" (10 repetitions), "PCA-only," and "PCA + genSD." Tibial and common peroneal nerve segmentations and masks were generated from volunteer diffusion data. Quantitative (SNR and contrast-to-noise ratio [CNR]) values were calculated. Three radiologists qualitatively evaluated nerve conspicuity for each method. The two denoising methods were also performed in three patients with peripheral neuropathies. STATISTICAL TESTS: For healthy volunteers, calculations included SNR and CNRFA (computed using FA values). Coefficient of variation (CV%) of CNRFA quantified within-subject reproducibility. Groups were compared with two-sample t-tests (significance P < 0.05; two-tailed, Bonferroni-corrected). Odds ratios (ORs) quantified the relative rates of each of three radiologists confidently identifying a nerve, per slice, for the four methods. RESULTS: "PCA + genSD" yielded the highest SNR (meanoverall = 14.83 ± 1.99) and tibial and common peroneal nerve CNRFA (meantibial = 3.45, meanperoneal = 2.34) compared to "original" (P SNR < 0.001; P CNR = 0.011) and "PCA-only" (P SNR < 0.001, P CNR < 0.001). "PCA + genSD" had higher within-subject reproducibility (low CV%) for tibial (6.04 ± 1.98) and common peroneal nerves (8.27 ± 2.75) compared to "original" and "PCA-only." The mean FA was higher for "original" than "average" (P < 0.001), but did not differ significantly between "average" and "PCA + genSD" (P = 0.14). "PCA + genSD" had higher tibial and common peroneal nerve conspicuity than "PCA-only" (ORtibial = 2.50, P < 0.001; ORperoneal = 1.86, P < 0.001) and "original" (ORtibial = 2.73, P < 0.001; ORperoneal = 2.43, P < 0.001). DATA CONCLUSION: PCA + genSD denoising method improved SNR, CNRFA , and within-subject reproducibility (CV%) without biasing FA and nerve conspicuity. This technique holds promise for facilitating more reliable, unbiased diffusion measurements of peripheral nerves. LEVEL OF EVIDENCE: 2 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2020;51:1128-1137.

Optimal Choice of Ultrasound-Based Measurements for the Diagnosis of Ulnar Neuropathy at the Elbow: A Meta-Analysis of 1961 Examinations.

OBJECTIVE. The purpose of this study was to determine the optimal ultrasound (US) measurement technique and cutoff value for the diagnosis of ulnar neuropathy at the elbow. MATERIALS AND METHODS. A systematic literature search was conducted of the PubMed, Embase, Scopus, and Web of Science databases for studies evaluating the diagnostic accuracy of US of patients with ulnar neuropathy at the elbow before April 2019. Random-effects modeling was performed to compare the sensitivity, specificity, and diagnostic odds ratio (DOR) of different US measurements, including diameter and cross-sectional area (CSA) of the nerve at the medial epicondyle or proximal and distal levels, maximal diameter, maximal CSA, and nerve ratios. Sensitivity and metaregression analyses were performed to assess the impact of clinical and imaging-based variables on the DOR of US. RESULTS. Among 820 retrieved studies, 19 studies (1961 examinations) were included. Measuring the CSA of the ulnar nerve at the medial epicondyle with a cutoff value greater than 10-10.5 mm2 had higher sensitivity (80.4%, 95% CI, 75.4-84.7%) than other techniques. Nerve ratios had higher specificity (89.1%, 95% CI, 85.8-91.8%) than other measurements; however, the definition of ratios and cutoff values varied across studies. ROC analysis showed higher diagnostic performance for measuring CSA at the medial epicondyle (AUC, 0.931). The mean CSA value was a significant predictor of the DOR of US (ß coefficient, 0.307 ± 0.074; p < 0.001). Every 1-mm2 larger CSA was associated with a 36% increase in DOR. The diagnostic performance of US was the same in any degree of elbow flexion. CONCLUSION. Measuring CSA of the ulnar nerve at the medial epicondyle has sensitivity and diagnostic performance superior to those of other techniques for the diagnosis of ulnar neuropathy at the elbow.

Magnetic resonance evaluation of the pediatric knee after arthroscopic fixation of osteochondral lesions with biodegradable nails.

PURPOSE: To use magnetic resonance imaging (MRI) to investigate the knee joint of children following arthroscopic fixation of osteochondral lesions using bioabsorbable nails and to correlate these imaging findings with time from arthroscopic treatment and with risk factors at the time of imaging. MATERIALS AND METHODS: Our study included postarthroscopic MRI studies from 58 children (mean age at arthroscopy, 13.8 + 2.1 years) who have undergone bioabsorbable nail fixation of unstable osteochondral lesions between February 1, 2011 and September 30, 2017. All studies were retrospectively reviewed for broken nails, intra-articular debris, and internal knee derangement. Demographic information and information pertaining to active symptoms was obtained from both MRI questionnaire that was completed at the time of the study and clinical note that preceded the study. Marginal logistic regression models estimated using generalized estimating equations (GEE) were used to identify factors associated with a broken nail and joint effusion. RESULTS: A total of 104 postoperative studies were reviewed, which included 60 with symptoms and 44 without symptoms. Nail breakage was present in 38 (36.6%) studies and associated with presence of symptoms (OR 2.43, p = 0.036) and effusion (OR 2.76, p = 0.025). An effusion was present in 40 (38.5%) studies which decreased with increasing time from treatment (OR 0.89, p = 0.007) and increased with symptoms (OR 10.87, p < 0.001). Meniscal tear was present on 8 (7.7%) and chondral irregularity on 14 (13.5%) studies. CONCLUSION: Broken nail, effusion, and less commonly, meniscal tears and chondral irregularity, are all complications that can arise following fixation of osteochondral lesions with bioabsorbable nails. MRI can serve as a valuable tool in assessing these complications.

Reverse total shoulder arthroplasty: an imaging overview.

Although not as common as hip or knee arthroplasty, shoulder arthroplasty is becoming a more common procedure. Reverse total shoulder arthroplasty (RTSA) is known to be an effective surgical procedure for massive irreparable rotator cuff tears, comminuted proximal humerus fractures, and revision shoulder arthroplasty. The utilization of RTSA has been increasing, and although complications following reverse arthroplasty have been reported, there are few reports in the literature that focus on the imaging features of RTSA. Herein, we demonstrate the biomechanics of RTSA, prosthesis components, indications, and imaging features of the normal postoperative appearance and various complications after RTSA. Familiarization with the normal and abnormal imaging appearances after RTSA can be helpful for appropriate management of patients.

Imaging evaluation of polyethylene liner dissociation in total hip arthroplasty.

OBJECTIVE: To describe the imaging findings of polyethylene liner dissociation in total hip arthroplasty. MATERIALS AND METHODS: Retrospective search of our institution's radiology database identified 12 patients with polyethylene liner dissociation of a total hip arthroplasty. Clinical and operative notes were reviewed. All radiological studies were reviewed independently by two radiologists. RESULTS: Among 12 patients (seven females/five males; mean age: 67 years; median interval after surgery at diagnosis: 8.5 months) with polyethylene liner dissociation, 11 had radiographs, six had CT, seven had MRI, and two had arthrography. "Bubble sign" and "crescent sign" on radiography were insensitive, seen only in three patients, but all showed abrupt eccentric positioning of the femoral head. CT identified the dislocated liner in five of six patients but failed to identify one liner, which was partially associated with the acetabular cup. MRI identified the dislocated liner in all seven patients, with the MAVRIC (multiacquisition variable resonance image combination) sequences either increasing the diagnostic confidence relative to the routine pulse sequences or being the sole sequences in which the liner can be identified if the liner remained partially associated with the acetabular cup. Arthrography identified the dislocated liner in one of two patients. CONCLUSIONS: Previously described radiographic signs of polyethylene liner dissociation are insensitive, but abrupt eccentric positioning of the femoral head in the correct clinical context is highly suggestive of the diagnosis. MRI and CT can accurately localize the displaced liner. MAVRIC is particularly helpful if the dislocated liner remains partially associated with the acetabular cup.

Pseudoaneurysm after total knee arthroplasty: imaging findings in 7 patients.

OBJECTIVE: To describe the clinical presentation of arterial pseudoaneurysms following total knee arthroplasty (TKA) and their diagnostic imaging features on ultrasound and magnetic resonance angiography (MRA) in 7 patients. MATERIALS AND METHODS: A search of our radiology report database from 2007 to 2017 yielded 7 patients with a pseudoaneurysm diagnosed by imaging after TKA. Clinical notes and imaging were reviewed. RESULTS: All 7 patients were male and ranged in age from 53 to 68 (mean 61) years. All patients presented with a painful swollen knee and hemarthrosis within the first month following surgery. Five patients presented after primary TKA. One patient presented after explantation for septic arthritis and another after partial synovectomy for septic arthritis without explantation. Ultrasound identified the pseudoaneurysm as a hypoechoic or hyperechoic mass with a "yin-yang" appearance of turbulent arterial flow and associated complex joint effusion. On MRA, the pseudoaneurysm was a mass next to a parent artery showing avid contrast enhancement in the arterial phase that persisted into the venous phase and washed out in the late venous phase. Six pseudoaneurysms arose from lateral geniculate arteries and 1 from a medial geniculate artery. There were no popliteal artery pseudoaneurysms. Five patients were treated endovascularly, 1 patient thrombosed without intervention, and 1 patient was treated with open surgery. CONCLUSION: Pseudoaneurysm is a potential source of a painful swollen knee with hemarthrosis or a drop in hematocrit after TKA and can be identified with either ultrasound or MRA.

Imaging of the post-operative medial elbow in the overhead thrower: common and abnormal findings after ulnar collateral ligament reconstruction and ulnar nerve transposition.

Ulnar collateral ligament (UCL) reconstruction is now being performed more commonly and on younger patients than in prior decades. As a result, radiologists will increasingly be asked to evaluate elbow imaging of patients presenting with pain who have had UCL reconstruction. It is essential for radiologists to understand the normal and abnormal imaging appearances after UCL reconstruction and ulnar nerve transposition, which is also commonly performed in overhead-throwing athletes. Doing so will allow radiologists to provide accurate interpretations that appropriately guide patient management.

Technical Developments: Zero Echo Time Imaging of the Shoulder: Enhanced Osseous Detail by Using MR Imaging.

Purpose To determine the intermodality agreement of morphologic grading and clinically relevant quantitative measurements between computed tomography (CT) and zero echo time (ZTE) magnetic resonance (MR) imaging of the shoulder. The primary objective was to demonstrate the clinical applicability of ZTE in osseous shoulder imaging. Materials and Methods Thirty-four patients undergoing standard-of-care (SOC) MR imaging with concomitant CT were enrolled in this institutional review board-approved study. ZTE images were acquired after SOC MR imaging. Glenoid morphology (version, vault depth, erosion), injury or disease (osteoarthritis, Bankart and Hill-Sachs lesions, subchondral cysts), and evidence of prior surgery were graded or measured. κ Values, intraclass correlation coefficients (ICCs), and Bland-Altman limits of agreement were used to establish agreement. Qualitative comparison of osseous findings was performed between ZTE and SOC MR imaging. Results Binary classification and nominal/ordinal grades showed substantial or better agreement between raters and modalities (κ or ICC > 0.6). Continuous measurements exhibited strong correlation between raters and modalities, although not universally. Bankart ICCs were not significant, owing to low prevalence. ZTE exhibited greater conspicuity of enthesopathic cysts and marrow edema. In 21 of 34 cases, ZTE imaging of osseous features exceeded SOC MR imaging. Conclusion ZTE MR imaging provides "CT-like" contrast for bone. The results of this study demonstrate strong intermodality agreement between measurements and grades from CT and ZTE images in a cohort of patients undergoing imaging with both modalities. A majority of ZTE image sets provided superior visualization of osseous features when compared with SOC MR image sets. This superiority coupled with strong quantitative agreement with CT suggests that ZTE may be used clinically in lieu of CT in some cases. © RSNA, 2017 Online supplemental material is available for this article.