Update on elbow arthroplasties with emphasis on imaging.

Elbow arthroplasty is increasing in popularity and can be used to treat many conditions, such as trauma, primary and secondary osteoarthritis, inflammatory arthritis, and osteonecrosis. Total elbow arthroplasty (TEA) is reserved for patients with severe symptoms refractory to more conservative management. In addition to TEA, hemi-arthroplasty, interposition arthroplasty, and resection arthroplasty also play roles in the management of elbow pain. There are specific indications for each type of arthroplasty. Postoperative complications may occur with elbow arthroplasties and may be surgery or hardware related. Imaging is important in both pre-operative planning as well as in post-surgical follow-up. This article reviews the different types of elbow arthroplasties, their indications, their normal postoperative imaging appearances, and imaging findings of potential complications.

Imaging of osteoarthritis from the ankle through the midfoot.

Ankle, hindfoot, and midfoot osteoarthritis (OA) is most commonly posttraumatic and tends to become symptomatic in younger patients. It often results from instability due to insufficiency of supportive soft tissue structures, such as ligaments and tendons. Diagnostic imaging can be helpful to detect and characterize the distribution of OA, and to assess the integrity of these supportive structures, which helps determine prognosis and guide treatment. However, the imaging findings associated with OA and instability may be subtle and unrecognized until the process is advanced, which may ultimately limit therapeutic options to salvage procedures. It is important to understand the abilities and limitations of various imaging modalities used to assess ankle, hindfoot, and midfoot OA, and to be familiar with the imaging findings of OA and instability patterns.

Musculoskeletal Manifestations of COVID-19: Currently Described Clinical Symptoms and Multimodality Imaging Findings.

COVID-19, the clinical syndrome produced by infection with SARS-CoV-2, can result in multisystem organ dysfunction, including respiratory failure and hypercoagulability, which can lead to critical illness and death. Musculoskeletal (MSK) manifestations of COVID-19 are common but have been relatively underreported, possibly because of the severity of manifestations in other organ systems. Additionally, patients who have undergone sedation and who are critically ill are often unable to alert clinicians of their MSK symptoms. Furthermore, some therapeutic measures such as medications and vaccinations can worsen existing MSK symptoms or cause additional symptoms. Symptoms may persist or occur months after the initial infection, known as post-COVID condition or long COVID. As the global experience with COVID-19 and the vaccination effort increases, certain patterns of MSK disease involving the bones, muscles, peripheral nerves, blood vessels, and joints have emerged, many of which are likely related to a hyperinflammatory host response, prothrombotic state, or therapeutic efforts rather than direct viral toxicity. Imaging findings for various COVID-19-related MSK pathologic conditions across a variety of modalities are being recognized, which can be helpful for diagnosis, treatment guidance, and follow-up. The online slide presentation from the RSNA Annual Meeting is available for this article. ©RSNA, 2022.

Posttreatment Imaging of the Wrist and Hand: Update 2022.

Common indications for surgical procedures of the wrist and hand include acute fractures or fracture-dislocations; nonunited fractures; posttraumatic, degenerative, and inflammatory arthritides and tendinopathies; injuries to tendons, ligaments, and the triangular fibrocartilage complex; and entrapment neuropathies. Soft tissue or osseous infections or masses may also need surgical treatment. Several of these procedures require surgical hardware placement, and most entail clinical follow-up with periodic imaging. Radiography should be the first imaging modality in the evaluation of the postoperative wrist and hand. Computed tomography, magnetic resonance imaging, diagnostic ultrasonography, and occasionally nuclear medicine studies may be performed to diagnose or better characterize suspected postoperative complications. To provide adequate evaluation of postoperative imaging of the wrist and hand, the interpreting radiologist must be familiar with the basic principles of these surgical procedures and both the imaging appearance of normal postoperative findings as well as the potential complications.

Magnetic resonance imaging of rheumatological diseases.

Magnetic resonance imaging (MRI) is extremely useful in the early diagnosis of rheumatologic diseases, as well as in the monitoring of treatment response and disease progression to optimize long-term clinical outcomes. MRI is highly sensitive and specific in detecting the common findings in rheumatologic diseases, such as bone marrow oedema, cartilage disruption, articular erosions, joint effusions, bursal effusions, tendon sheath effusions, and synovitis. This imaging modality can demonstrate structural changes of cartilage and bone destruction years earlier than radiographs. Rheumatoid arthritis, crystal deposition diseases (including gouty arthropathy and calcium pyrophosphate deposition disease), seronegative spondyloarthropathies (including psoriatic arthritis, reactive arthritis, ankylosing spondylitis), and osteoarthritis have characteristic appearances on MRI. Contrast-enhanced MRI and diffusion-weighted imaging can provide additional evaluation of active synovitis. This article describes the MRI findings of normal joints, as well as the pathophysiological mechanisms and typical MRI findings of rheumatoid arthritis, gouty arthritis, calcium pyrophosphate deposition disease, psoriatic arthritis, reactive arthritis, ankylosing spondylitis, and osteoarthritis.

Magnetic resonance imaging of musculoskeletal infections.

Magnetic resonance imaging (MRI) is a powerful imaging modality in the evaluation of musculoskeletal (MSK) soft tissue, joint, and bone infections. It allows prompt diagnosis and assessment of the extent of disease, which permits timely treatment to optimize long-term clinical outcomes. MRI is highly sensitive and specific in detecting the common findings of MSK infections, such as superficial and deep soft tissue oedema, joint, bursal and tendon sheath effusions, lymphadenopathy, bone marrow oedema, erosive bone changes and periostitis, and bone and cartilage destruction and sequestration. Contrast-enhanced MRI allows detection of non-enhancing fluid collections and necrotic tissues, rim-enhancing abscesses, heterogeneously or diffusely enhancing phlegmons, and enhancing active synovitis. Diffusion-weighted imaging (DWI) is useful in detecting soft-tissue abscesses, particularly in patients who cannot receive gadolinium-based intravenous contrast. MRI is less sensitive than computed tomography (CT) in detecting soft-tissue gas. This article describes the pathophysiology of pyogenic MSK infections, including the route of contamination and common causative organisms, typical MR imaging findings of various soft tissue infections including cellulitis, superficial and deep fasciitis and necrotizing fasciitis, pyomyositis, infectious bursitis, infectious tenosynovitis, and infectious lymphadenitis, and of joint and bone infections including septic arthritis and osteomyelitis (acute, subacute, and chronic). The authors also discuss MRI findings and pitfalls related to infected hardware and diabetic foot infections, and briefly review standards of treatment of various pyogenic MSK infections.

Pulley, Flexor, and Extensor Tendon Injuries of the Hand.

Tendon injuries represent the second most common injury of the hand (after fractures) and are a common scanning indication in radiology. Pulley injuries are very frequent in rock climbers with the A2 pulley the most commonly affected. Tendon and pulley injuries can be reliably evaluated using ultrasound (US) and magnetic resonance imaging (MRI). US can be postulated as a first-line imaging modality, allowing dynamic examination. MRI is essential for cases with ongoing diagnostic doubt post-US and also for preoperative pulley reconstruction assessment.

Diffuse tensor imaging of lower extremities: a novel MR imaging technique for chemotherapy-induced peripheral neuropathy.

PURPOSE: Chemotherapy-induced peripheral neuropathy (CIPN) is caused by drug-induced damage to the axons which is not detected easily due to lack of reliable, clinically applicable modalities. Diffuse tensor imaging (DTI) allows for quantitative measurements of fractional anisotropy (FA) and apparent diffusion coefficient (ADC), which have been shown to detect nerve injury by Magnetic Resonance Imaging (MRI). METHODS: We sought to evaluate if DTI could be used for detection of CIPN in patients with breast cancer treated with a taxane. Patients with h/o exposure to neurotoxic chemotherapy, diabetes, or peripheral neuropathy were excluded. Patients completed pre- and post-chemotherapy MRI of bilateral legs and FACT&GOG-Ntx. Genotyping of single-nucleotide variations (SNVs) was performed to detect known associations with CIPN. RESULTS: We had 14 evaluable patients in this prospective trial. Mean FA values post-chemotherapy were significantly lower than baseline at mid-calf (p < 0.0001) and ankle (p = 0.03). We did not find any significant change in mean ADC values. In patients without symptomatic neuropathy, mean FA values decreased more than symptomatic patients at mid-calf (p < 0.001). Of the 41 genotyped SNVs, only rs8110536 was found to be significantly associated with development of CIPN. CONCLUSIONS: Our results show that FA values are indicative of CIPN and differential changes in FA values in symptomatic versus asymptomatic patients highlights its potential to be further studied as a predictive biomarker for CIPN. This is the first study to highlight a non-invasive, imaging based, objective biomarker which, if validated, can be translated into clinic easily.

Magnetic resonance imaging of the elbow.

Elbow pain can cause disability, especially in athletes, and is a common clinical complaint for both the general practitioner and the orthopaedic surgeon. Magnetic resonance imaging (MRI) is an excellent tool for the evaluation of joint pathology due to its high sensitivity as a result of high contrast resolution for soft tissues. This article aims to describe the normal imaging anatomy and biomechanics of the elbow, the most commonly used MRI protocols and techniques, and common MRI findings related to tendinopathy, ligamentous and osteochondral injuries, and instability of the elbow.

Magnetic resonance imaging of the spine.

Low back and neck pain are common and result in significant patient disability and health care expenditure. When conservative treatment fails or worrisome clinical findings are present, magnetic resonance imaging (MRI) is the imaging modality of choice to assess the cause and complicating features of spine pain. There are many potential aetiologies of spine pain with similar clinical presentation, including degenerative changes, infection, and insufficiency and pathologic fractures. MRI allows for the differentiation of these sources of spine pain and potential complicating features, permitting the appropriate direction of therapy.

Impact of Dual-Energy CT Postprocessing Protocol for the Detection of Gouty Arthritis and Quantification of Tophi in Patients Presenting With Podagra: Comparison With Ultrasound.

OBJECTIVE. The objective of our study was to compare ultrasound (US) tophus and monosodium urate (MSU) deposit detection and US tophus size in the metatarsophalangeal (MTP) 1 joint with dual-energy CT (DECT) using two DECT postprocessing protocols in patients presenting with podagra. SUBJECTS AND METHODS. Seventy-five consecutive patients with podagra (66 men and nine women; mean age, 65.6 years; age range, 33-88 years) and 75 control subjects with MTP 1 joint osteoarthritis (49 men and 26 women; mean age, 63.0 years; age range, 35-87 years) prospectively underwent US and DECT between 2016 and 2018 to assess the MTP 1 joint. Two Syngovia postprocessing DECT protocols with different minimum attenuation thresholds of 150 HU (DECT 150 protocol) versus 120 HU (DECT 120 protocol) and the same maximum attenuation threshold (500 HU) and constant kilovoltage setting of tubes A and B at 80 and 140 kVp were evaluated. Interobserver variability of the two DECT protocols was calculated and compared with that of US. RESULTS. The postprocessing DECT 150 protocol was positive for tophus detection in 55 of 75 patients (73.3%) with podagra, whereas the postprocessing DECT 120 protocol detected MSU deposits in all 75 patients (100%). Tophus size assessed using the DECT 120 protocol showed an improved correlation with tophus size detected on US (p < 0.01). Interobserver variability of DECT was improved when using the DECT 120 protocol (p < 0.01). CONCLUSION. The postprocessing DECT 120 protocol enables improved visualization of MSU deposits and provides more accurate information about tophus size that better correlates with tophus size on US compared with the standard postprocessing DECT 150 protocol.

Radiologic Evaluation of Lower Leg, Ankle, and Foot Fracture Fixation Hardware.

Radiologists should be familiar with basic principles of fracture fixation and the normal imaging appearances of implant constructs and their complications. The surgeon's selection of external fixation, intramedullary nail fixation, open reduction and internal fixation, or some combination depends on patient factors, fracture configuration, injury to the soft tissue envelope, and surgeon experience. Complications including loss of fixation with resultant malalignment, nonunion, infection, and posttraumatic osteoarthritis present additional challenges for the surgeon as well as the radiologist. This article reviews the rationale behind fracture fixation in fractures of the lower leg, ankle, and foot. Examples of postoperative complications are also reviewed.

Update on Imaging of Knee Arthroplasties: Normal Findings and Hardware Complications.

Total knee arthroplasty (TKA) is the most common joint replacement performed. This article reviews the normal appearance of TKA including the most common types of arthroplasties as well as complications. Common complications at the present time are infection, aseptic loosening, and instability. Rarer complications such as polyethylene wear, periprosthetic fracture, and soft tissue pathology are also discussed. Although the mainstay of imaging is radiographs, newer techniques in TKA imaging such as computed tomography and magnetic resonance imaging are also reviewed.

Update on Imaging of Spinal Fixation Hardware.

This article discusses instrumented spinal surgeries, the radiologic assessment of spinal fixation hardware, and the potential complications of spinal hardware. Radiography is the standard for the postoperative assessment of spinal hardware. Computed tomography and magnetic resonance imaging play a valuable role in the detection of hardware and postsurgical-related complications such as infection, pseudarthrosis, and malpositioned instrumentation. Familiarity with the normal imaging appearance of implanted spinal hardware along with the expected progression of normal postoperative osseous arthrodesis enables recognition of potential complications and helps facilitate appropriate clinical management.

Nerve Entrapment Syndromes at the Wrist and Elbow by Sonography.

Nerve entrapment syndromes of the upper extremity are associated with structural abnormalities or by an intrinsic abnormality of the nerve. Nerve entrapment syndromes generally have a typical clinical presentation, and findings on physical examination and in conjunction with electrodiagnostic studies imaging is used to evaluate the cause, severity, and etiology of the entrapment. With the development of high-frequency linear array transducers (12-24 MHz), ultrasound (US) is incomparable in terms of spatial resolution to depict morphological aspects and changes in nerves. US can identify the abnormalities causing entrapment, such as fibrous bands, ganglia, anomalous muscles, and osseous deformities, with the advantage of dynamic assessment under active and passive examination. US is a unique diagnostic modality that allows superb visualization of both large and small peripheral terminal nerve branches of the upper extremity and enables the correct diagnosis of various nerve entrapment syndromes.

Imaging of Postoperative Infection at the Knee Joint.

Postoperative infections of the knee are uncommon but may occur with joint arthroplasties, fracture fixation, or after arthroscopic procedures. The ultimate diagnosis is made by joint aspiration or tissue sampling. Joint aspiration and tissue sampling can be performed under imaging guidance or intraoperatively. Imaging is an important adjunct to clinical and laboratory findings and should start with radiographs. Cross-sectional imaging including magnetic resonance (MR) imaging, computed tomography (CT), nuclear studies, and ultrasound (US) are frequently used if the diagnosis is in doubt and to evaluate the extent of disease. We discuss the current algorithm in the diagnosis of various postoperative infections of the knee joint. The article addresses the utility of radiography, MR imaging, CT, US, and the most commonly used nuclear studies in the diagnosis of various postoperative knee infections and the imaging appearances of these infections on each of these diagnostic modalities.

Sonoelastography of the Common Flexor Tendon of the Elbow with Histologic Agreement: A Cadaveric Study.

Purpose To determine the correlation of the results of conventional B-mode ultrasonography (US) and compression sonoelastography with histologic results in common flexor tendons of the elbow in human cadavers. Materials and Methods Twenty-five common flexor tendons were evaluated in 16 fresh, unembalmed cadavers of 11 women with a median age of 85 years (range, 71-101 years) and five men with a median age of 78 years (range, 70-88 years). Informed consent was provided according to the last will of the donors. B-mode US results were classified as grade 1, normal tendon with homogeneous fibrillar pattern; grade 2, tendon thickening or hypoechoic areas and/or calcifications in less than 30% of the tendon; or grade 3, hypoechoic areas and/or calcifications greater than 30% of the tendon. Sonoelastographic results were grade 1, blue (hardest) to green (hard); grade 2, yellow (soft); and grade 3, red (softest). The intraclass correlation coefficient was calculated to determine agreement with histologic findings for each B-mode US, sonoelastographic, and combined B-mode US and sonoelastographic examination. Histologic results were grade 1, normal, with parallel fibrillar pattern; grade 2, mild tendinopathy, with cellular infiltration, angiogenesis, or fatty vacuoles; or grade 3, severe tendinopathy, with loss of parallel collagen structure and necrosis. Results Histologic alterations were detected in 44% (11 of 25) of biopsy specimens. Intraclass correlation with histologic results was 0.57 for B-mode US, 0.68 for sonoelastography, and 0.84 for the combination of the two approaches. Conclusion The addition of sonoelastography to B-mode US provided statistically significant improvement in correlation with histologic results compared with the use of B-mode US alone (P < .02). © RSNA, 2016 Online supplemental material is available for this article.

Extensor tendinopathy of the elbow assessed with sonoelastography: histologic correlation.

PURPOSE: To compare agreement between conventional B-mode ultrasound (US) and compression sonoelastography (SEL) of the common extensor tendons of the elbow with histological evaluation. MATERIALS AND METHODS: Twenty-six common extensor tendons were evaluated in 17 cadavers (11 females, median age 85 years and 6 males, median age 80 years). B-mode US was graded into: Grade 1, homogeneous fibrillar pattern; grade 2, hypoechoic areas and/or calcifications <30%; and grade 3 > 30%. SEL was graded into: Grade 1 indicated blue (hardest) to green (hard); grade 2 yellow (soft); and grade 3 red (softest). B-mode US, SEL, and a combined grading score incorporating both were compared to histological findings in 76 biopsies. RESULTS: Histological alterations were detected in 55/76 biopsies. Both modalities showed similar results (sensitivity, specificity, and accuracy 84%, 81%, and 83% for B-mode US versus 85%, 86%, and 86% for SEL, respectively, P > 0.3). However, a combination of both resulted in significant improvement in sensitivity (96%, P < 0.02) without significant change in specificity (81%, P < 0.3), yielding an improved overall accuracy (92%). CONCLUSION: Combined imaging of the extensor tendons with both modalities is superior to either modality alone for predicting the presence of pathologic findings on histology. KEY POINTS: • Combination of B-mode US and SEL proved efficiency in diagnosing lateral epicondylitis. • Combination of B-mode US and SEL in lateral epicondylitis correlates to histology. • Combination of both modalities provides improved sensitivity without loss of specificity.

Ultrasound Evaluation of Morton Neuroma Before and After Laser Therapy.

OBJECTIVE: The objective of our study was to retrospectively assess for differences in imaging appearances of Morton neuromas before and after laser therapy using diagnostic ultrasound (US). MATERIALS AND METHODS: A retrospective review was performed to identify patients who underwent US imaging to evaluate for Morton neuroma during the study period (June 1, 2013-July 1, 2014); of the 42 patients identified, 21 underwent US evaluations before and after laser therapy. US reports and images were reviewed and correlated with clinical history. The final study group consisted of 21 patients who had a total of 31 Morton neuromas evaluated using US after treatment. A retrospective review was then performed to characterize the appearances of these lesions before and after therapy followed by an analysis of variables. RESULTS: Retrospective US review of 31 pretreatment Morton neuromas showed fusiform, heterogeneously hypoechoic masses with well-defined borders in most cases and that pain was reported when transducer pressure was applied in 97% (30/31) of cases. After treatment, lesions showed ill-defined borders (23/31), and pain with application of transducer pressure was either significantly decreased or absent (29/31); these findings were concordant with the clinical findings. Both of these characteristics were statistically significant (p < 0.0001). In addition, more Morton neuromas occurred in the second intermetatarsal space than in the third intermetatarsal space (p < 0.0001). CONCLUSION: US may be used to identify posttreatment changes after laser therapy of Morton neuromas. Posttreatment changes include ill-defined borders and less pain or the absence of pain with the application of transducer pressure. These criteria may be applied in future clinical studies evaluating the efficacy of laser therapy for Morton neuroma.

Shear-Wave Elastography: Basic Physics and Musculoskeletal Applications.

In the past 2 decades, sonoelastography has been progressively used as a tool to help evaluate soft-tissue elasticity and add to information obtained with conventional gray-scale and Doppler ultrasonographic techniques. Recently introduced on clinical scanners, shear-wave elastography (SWE) is considered to be more objective, quantitative, and reproducible than compression sonoelastography with increasing applications to the musculoskeletal system. SWE uses an acoustic radiation force pulse sequence to generate shear waves, which propagate perpendicular to the ultrasound beam, causing transient displacements. The distribution of shear-wave velocities at each pixel is directly related to the shear modulus, an absolute measure of the tissue's elastic properties. Shear-wave images are automatically coregistered with standard B-mode images to provide quantitative color elastograms with anatomic specificity. Shear waves propagate faster through stiffer contracted tissue, as well as along the long axis of tendon and muscle. SWE has a promising role in determining the severity of disease and treatment follow-up of various musculoskeletal tissues including tendons, muscles, nerves, and ligaments. This article describes the basic ultrasound physics of SWE and its applications in the evaluation of various traumatic and pathologic conditions of the musculoskeletal system. ©RSNA, 2017.