Ultrasound assessment of synovitis in total knee replacements: concordance with MR imaging and joint aspiration.

OBJECTIVE: To determine if diagnostic ultrasound can reliably distinguish between synovial patterns of prosthetic joint infection and polymeric wear in total knee replacements. METHODS AND METHODS: This retrospective study was approved by our hospital IRB. Using the radiology report database, MR examinations performed within a week of diagnostic ultrasound and/or ultrasound-guided aspiration were identified. This yielded (1) 24 cases with MR and ultrasound comparisons; (2) 44 cases with MR, ultrasound, and aspiration comparisons; and (3) 92 cases with ultrasound and aspiration comparisons. The MR studies were reviewed by a musculoskeletal radiologist. The ultrasound studies were each reviewed by 2 other musculoskeletal radiologists. Each study was graded for synovial pattern indicating infection, polymeric wear, or normal/nonspecific. Agreement between the MR grader and the ultrasound graders as well as ultrasound inter-rater agreement were assessed using k statistics. Sensitivity, specificity, positive predictive value, and negative predictive value of ultrasound were calculated. RESULTS: Agreement between ultrasound and MR imaging was fair to moderate: k of 0.27 (95% CI: 0.04, 0.50) and 0.44 (95% CI: 0.23, 0.65) for ultrasound raters 1 and 2, respectively. Inter-rater agreement between ultrasound graders 1 and 2 was moderate, with k of 0.56 (95% CI: 0.42, 0.70). Ultrasound sensitivities for infection were 0.13 and 0.09, while specificities were 0.94 and 0.98. Ultrasound sensitivities for polymeric wear were 0.38 and 0.62 with specificities of 0.90 and 0.76. CONCLUSION: Ultrasound does not perform well in distinguishing patterns of synovitis either compared to MRI or a reference standard of aspiration/clinical follow-up.

When to lavage in the absence of a sonographically visible joint effusion in painful total knee arthroplasty: a retrospective longitudinal study.

OBJECTIVE: To determine if knee arthroplasty without sonographically visible effusion needs to undergo lavage to rule out infection. METHODS: Patients were accrued by a retrospective search of a longitudinally maintained radiology database looking for patients referred for ultrasound guided aspiration of suspected TKA infection. Clinical presentations, laboratory tests, intraoperative findings, and follow-up were reviewed. RESULTS: Four hundred sixty-nine patients were included (mean age of 67 years (range, 36-91)) including 251 females. Four hundred three patients had effusions, of which 57 were infected based on ultrasound-guided and surgical aspirates. Sixty-four patients lacked effusions, of which 47 underwent lavage at the clinicians' request, with 6/47 infected. Nineteen patients without effusion were not lavaged at the clinicians' request due to low suspicion, and none were infected. Patients with positive lavage cultures all had clinical risk factors. Infection rates were significantly higher in patients with joint effusion and clinical suspicion for infection compared to absent joint effusion and absent clinical suspicion. A significantly higher proportion of patients with hyperemia or moderate-severe synovial thickening on ultrasound were symptomatic and had joint effusion and positive joint cultures. Aspiration of native fluid had 85% sensitivity and 100% specificity while lavage had a sensitivity of 57% and specificity of 100%. Negative predictive value for native aspirates was 94% compared to 86% for lavage. CONCLUSION: A TKA with low clinical suspicion of infection does not need to undergo lavage in the absence of a sonographically visible effusion.

Diagnostic ultrasound and ultrasound-guided injections for peri-articular pain after knee replacement.

OBJECTIVE: The purpose of this technical report is to review the sonographic spectrum of abnormalities accounting for peri-articular pain after knee replacement surgery, as well as to demonstrate the clinical utility of ultrasound in the diagnosis and treatment of this subset of patients. MATERIALS AND METHODS: Utilizing an imaging report database, we performed a search for ultrasound examinations performed by a single radiologist for knee pain after knee arthroplasty at our institution over a 10-year period. The search yielded 63 patients, whom we have categorized by causative pathology, with representative diagnostic and procedural ultrasound images selected for inclusion. RESULTS: Our search yielded multiple causes of peri-articular knee pain after arthroplasty, including medial and lateral retinacular impingement and scarring, iliotibial band or conjoined tendon irritation, popliteus tendon impingement, medial collateral ligament impingement, pes anserine bursitis, and scarring of Hoffa's fat pad. CONCLUSION: While knee arthroplasty is an often-successful procedure, it can be complicated by post-operative peri-articular knee pain. Ultrasound provides a valuable tool for the diagnosis of painful peri-articular knee pathology, as it allows for both static and dynamic evaluation, as well as direct correlation with patient symptoms, and is not confounded by the metal components. In addition to its diagnostic utility, ultrasound can also guide diagnostic and/or therapeutic injections of anesthetic and corticosteroid. Given these advantages, ultrasound is an important tool in managing the painful post-arthroplasty knee.

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.

Ultrasound-guided injection of the pisotriquetral joint: technique and case series.

PURPOSE: To describe our techniques for ultrasound-guided injection of the pisotriquetral joint (PTJ), and to report our experience in a case series. METHODS: Between 7/1/14 and 11/30/20, we performed 42 injections in 33 patients with ulnar-sided wrist pain, referred by clinicians who suspected the PTJ as the pain generator. There were 16 males and 17 females, average age 46.7 years. The patients were positioned in one of five ways: sitting with the hand maximally supinated; sitting with the hand maximally pronated; supine with the elbow flexed across the chest and the ulnar aspect of the wrist facing upward; supine with the elbow flexed, the arm externally rotated, and the ulnar aspect of the wrist facing upward; prone with the symptomatic hand at their side and the ulnar aspect of the wrist facing upward. RESULTS: The procedures were performed by any of twelve fellowship-trained musculoskeletal radiologists. Fifteen patients reported immediate relief of symptoms, including 6 patients whose pisotriquetral joints were normal sonographically. Four patients underwent subsequent surgical excision of their pisiforms and the fifth underwent arthroscopic debridement of the pisotriquetral joint. CONCLUSION: Ultrasound is a facile imaging modality for guiding pisotriquetral injections, which may be accomplished with a variety of patient positions and injection techniques.

Ultrasound of Musculoskeletal Hematomas: Relationship of Sonographic Appearance to Age and Ease of Aspiration.

OBJECTIVE: The purpose of this study was to evaluate the safety and efficacy of ultrasound-guided aspiration of musculoskeletal hematomas, evaluate the associations between the sonographic appearance of hematomas and their age with ease of aspiration, and determine if there is an optimal time frame for aspiration. MATERIALS AND METHODS: A retrospective search of our radiology database was conducted using the keywords "hematoma" and "aspiration" for procedures performed from January 1, 2008, through September 28, 2017, by three fellowship-trained musculoskeletal radiologists. Associations between the ease of aspiration and echotexture of the hematoma and between the ease of aspiration and age of the hematoma were assessed with a marginal ordinal logistic regression model to account for patient-level clusters. Pairwise comparisons of the ease of aspiration between the different echotextures were adjusted for multiple comparisons with the Tukey-Kramer method. This same method was also used to calculate the odds ratio (OR) for the age of the hematoma and ease of aspiration and decompression. Clinical follow-up was assessed for infection and symptomatic relief. RESULTS: The cohort was composed of 148 patients (77 male and 71 female patients) with a mean age of 48 years (age range, 16-80 years). One hundred patients underwent clinical follow-up: There were no instances of infection and all patients reported symptomatic relief. Marginal proportional odds model showed an OR of 3.77 when comparing the ease of aspiration between hypoechoic hematomas and hematomas showing the other echotextures combined (i.e., complex, heterogeneous, echo-genic), which was statistically significant (p = 0.010). The OR of the ease of aspiration in relation to the age of a hematoma for each additional week was 1.03 with a p value of 0.547, which shows that there is no correlation between the age of the hematoma and ease of aspiration. CONCLUSION: Ultrasound-guided aspiration of hematomas is a safe and effective procedure. The sonographic appearance of a hematoma is unrelated to its age. Although a hematoma with a hypoechoic appearance is easier to aspirate than hematomas with other echotextures, the appearance and age of a hematoma should not dissuade one from trying to aspirate it.

Quantitative assessment of change in upper extremity muscle stiffness following fluid injection using shear wave elastography.

OBJECTIVE: To quantitatively assess changes in muscle stiffness following intramuscular saline injection using shear wave elastography (SWE). MATERIALS AND METHODS: Thirty muscles (lateral deltoid (LD), biceps brachii (BB), brachialis, pronator teres (PT), flexor carpi radialis (FCR), flexor carpi ulnaris (FCU)) from fresh-frozen cadaveric specimens were injected with saline under ultrasound guidance. Pre- and post-injection muscle thickness (MT) (mm) and SWE (kPa) measurements were recorded. RESULTS: All muscles demonstrated a decrease in the mean SWE value post-injection, with the largest differences ± standard error noted in the LD (14.76 ± 3.55 kPa, p = 0.021) and brachialis muscles (12.02 ± 2.51 kPa, p = 0.013). Muscle thickness increased following injection, although the degree of changes poorly correlated with the change in SWE. CONCLUSION: In summary, following intramuscular injection of saline injection, a decrease in upper extremity muscle stiffness is detected using SWE. It is important to note that if performing a longitudinal assessment of muscle stiffness after intramuscular injection, saline will likely contribute to a decrease in muscle stiffness in the immediate post-injection time period.

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.

Three Degrees External to the Posterior Condylar Axis Has Little Relevance in Femoral Component Rotation: A Computed Tomography-Based Total Knee Arthroplasty Simulation Study.

BACKGROUND: Femoral component rotation in total knee arthroplasty (TKA) has a significant impact on balance and patellofemoral kinematics. However, normal anatomic relationships between rotational axes are poorly understood. As such, we sought to characterize anatomic femoral rotational axes in patients undergoing primary TKA. METHODS: We identified 100 patients who underwent a primary TKA with a preoperative computed tomography scan. The angles between the surgical epicondylar axis (SEA) and the anterior-posterior (AP) axis to the posterior condylar axis (PCA) were measured independently by a musculoskeletal fellowship-trained radiologist and a fellowship-trained arthroplasty surgeon. We simulated an ideal TKA in which the femoral component was placed exactly 3° external to the PCA and measured resulting rotation. RESULTS: The SEA was on average 1.5° externally rotated to the PCA (range 3.1° internal to 7.0° external). The AP axis was on average 4.5° externally rotated to the PCA (range 2.3° internal to 10.3° external). The AP axis was a mean 2.7° externally rotated to the SEA (range 6.3° internal to 10.3° external). Routinely setting femoral rotation 3° external to the PCA would result in only 51 (51%) TKAs within ±2° of the SEA and 23 (23%) femoral components internally rotated relative to the SEA. CONCLUSION: Normal anatomic rotational axes of arthritic knees are highly variable, with a 10° range in the SEA and 16° range in the AP axis. Routinely setting femoral rotation 3° external to the PCA will yield significant error in aligning the femoral component with either the SEA or AP axis.

Ultrasound-guided aspiration of anterior cruciate ligament mucinous cysts in the posterior intercondylar notch: Technique and short-term outcomes.

PURPOSE: To describe our technique of aspirating symptomatic anterior cruciate ligament (ACL) mucinous cysts in the posterior intercondylar notch with ultrasound guidance, and to detail short-term patient outcomes. METHODS: We identified 13 patients from February 2008 to May 2020 who underwent ultrasound-guided aspiration of symptomatic ACL mucinous cysts in the posterior intercondylar notch. Post-procedural imaging was reviewed to evaluate the degree of cyst decompression. Needle size was noted. Post-procedural symptomatology was also assessed. RESULTS: No or minimal fluid was initially aspirated in 11/13 (84.6%) patients. For the two patients in which the cysts were aspirated completely with initial needle placement, with no need for lavage, a 13-gauge trocar was utilized. Of the remaining cysts, 10/11 were aspirated with an 18-gauge needle and one with a 20-gauge needle. Subsequent lavage was performed in 10 of the remaining 11 patients. After lavage, in eight there was a reduction of at least 50% volume by retrospective image interpretation; of 25% to 50% volume in one patient and of less than 25% volume in one patient. Five of the 13 patients reported immediate post-procedural symptomatic relief. In the other patients, immediate efficacy or post-procedural symptomatology was not documented. CONCLUSION: Aspiration of symptomatic ACL mucinous cysts is a safe procedure and can provide symptomatic relief that may be temporary, but useful clinically. We recommend needles larger than 18 gauge for the best chance of successful aspiration.

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.

Ultrasound-Guided Biceps Tendon Sheath Injection: Spectrum of Preprocedure Appearances.

OBJECTIVES: To determine the frequency of ultrasound (US) appearances of the extra-articular long head of the proximal biceps tendon in patients referred for US-guided biceps tendon sheath injections. METHODS: We reviewed our US-guided biceps tendon sheath injections between January 2015 and December 2017, noting the appearance of the biceps tendon and sheath, as well as the needle size used, and what was injected. Clinical electronic medical records were also reviewed to determine safety and patients' responses. RESULTS: A total of 300 US-guided biceps tendon sheath injections were performed for anterior shoulder pain. Preliminary US evaluations revealed that 129 of 300 (43%) patients had a normal US appearance of the biceps tendon; 110 (36.6%) had tendinosis; 13 (4.3%) had tenosynovitis; 31 (10.3%) had both tendinosis and tenosynovitis; 8 (2.7%) had a biceps tendon tear; and 9 (3%) had a history of a tenodesis. Of 81 patients who had pain relief after the injection, 41 had a normal tendon appearance on US, and 40 had an abnormal US appearance. CONCLUSIONS: A large minority of patients with anterior shoulder pain clinically suspected to be due to the biceps tendon have a normal-appearing tendon and sheath. This should not dissuade the operator from performing the procedure.

Sonographic Findings Associated With Carpal Tunnel Syndrome.

PURPOSE: The purpose of this study was to identify associations between the clinical manifestations of carpal tunnel syndrome (CTS) and the sonographic measurements of the median nerve in the carpal tunnel. We hypothesized that sonographic changes in the median nerve from proximal to distal along the carpal tunnel would be associated with symptom severity scores. METHODS: We report on 38 patients with clinical signs and symptoms of CTS in a prospective investigation. Subjects underwent sonographic evaluation with measurement of median nerve cross-sectional area (CSA) at 3 locations: the level of the pronator quadratus, pisiform, and hamate. In addition, we measured dimensions of the carpal tunnel at the levels of the pisiform (inlet) and hamate (outlet). Finally, we recorded maximal thickness of the transverse carpal ligament (TCL). Patients underwent routine clinical evaluation and 31 patients had electrodiagnostic examination. Patients completed the Levine Katz Questionnaire (LKQ) to characterize severity of clinical symptoms. Each clinician was blinded to symptom severity scores. Pearson correlation coefficients were calculated to measure the relationship between LKQ score and sonographic measures. RESULTS: Median nerve CSA decreased over the course of the carpal tunnel from proximal to distal in 30 of 38 wrists. A greater absolute change in CSA of the median nerve over the course of the carpal tunnel between the pisiform and the hamate as well as between the pronator quadratus and the hamate correlated with increased severity of clinical symptoms. Increased thickening of the TCL also correlated with greater symptom severity scores. CONCLUSIONS: Changes in CSA of the median nerve as well as thickening of the TCL correlate with CTS severity. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.

Ultrasound-guided percutaneous treatment of volar radiocarpal ganglion cysts: Safety and efficacy.

PURPOSE: To determine the safety and efficacy of ultrasound (US)-guided percutaneous treatment of volar radiocarpal ganglion cysts. METHODS: The institutional review board approved the retrospective study of patients referred for US-guided percutaneous treatment of a volar radiocarpal ganglion cyst over a 5-year period. Treatment consisted of a combination of aspiration, lavage using anesthetic, wall fenestration, and steroid injection. Intraprocedural imaging and procedure notes were reviewed. Followup information was retrieved from postprocedure electronic medical records. RESULTS: Eighty-eight patients comprised our study group. Complete decompression of the ganglion cyst was achieved in 92% of cases immediately after treatment. There were no instances of hematoma or infection. Of 38 patients with available followup information, 66% had a ganglion cyst recurrence at a median time of 9 months, regardless of their initial size or the injection of steroids. Cysts with internal septa had a statistically significantly higher rate of recurrence (P = 0.033). CONCLUSIONS: US-guided percutaneous treatment of volar radiocarpal ganglion cysts is safe and ensures immediate decompression in most cases. However, cysts may recur, even after steroid injection or lavage.

Sonographic Evaluation of Superficial Peroneal Nerve Abnormalities.

OBJECTIVE: The objective of this study was to review the anatomy of the superficial peroneal nerve (SPN) and describe the sonographic appearances of various abnormalities affecting it. We performed a retrospective chart review of ultrasound (US) examinations of the SPN performed from 2014 to 2016. CONCLUSION: SPN abnormalities are well shown on US. Of 181 patients examined with US, the most commonly detected abnormality was scar encasement and neuroma or laceration.

Myositis and Fasciitis: Role of Imaging.

Imaging plays an important role in the evaluation of patients presenting with possible myositis, with magnetic resonance imaging the most appropriate modality but ultrasound also playing a complementary role. This article reviews the imaging appearance of the inflammatory myopathies, other forms of myositis, and mimickers of myositis, with a discussion of distinguishing features for each entity. The fascia and disease processes that preferentially involve the fascia are also reviewed.

Ultrasound Diagnosis of Osteophytic Impingement of the Popliteus Tendon After Total Knee Replacement.

We report our experience with 6 patients who had total knee replacements with lateral-sided knee pain, referred for ultrasound (US) assessment and US-guided injection. All cases showed an osteophyte within the popliteus sulcus of the lateral femoral condyle impinging on the adjacent tendon. Five of 6 patients reported improvement of symptoms immediately after US-guided injection of an anesthetic and a steroid. Ultrasound has a unique role in the imaging of knee replacements because of its real-time capabilities and absence of artifacts at the popliteus tendon origin.

Post-operative extra-spinal etiologies of sciatic nerve impingement.

Sciatica is a highly prevalent cause of morbidity, commonly resulting from intra-spinal pathological processes. Many cases can have extra-spinal etiologies and can be clinically challenging. Certain scenarios should suggest an extra-spinal etiology, particularly total and revision hip arthroplasty, surgical hip dislocation, hip arthroscopy, and surgery in the lithotomy position. We review the post-operative clinical scenarios where sciatic neuropathy may occur, along with the pertinent imaging findings.

Venous Hemodynamics After Total Hip Arthroplasty: A Comparison Between Portable vs Stationary Pneumatic Compression Devices and the Effect of Body Position.

BACKGROUND: Improvements in device design have allowed for portable pneumatic compression devices (PPCDs). However, portability results in smaller pumps that move less blood. Additionally, although patients often stand when wearing PPCDs, few studies have evaluated the hemodynamic effects of PCDs while standing. METHODS: A crossover study was performed to compare a PPCD (ActiveCare+S.F.T.; Medical Compression Systems, Or Akiva, Israel) to a stationary pneumatic compression device (SPCD) (VenaFlow; DJO Global, Carlsbad, CA) on hemodynamics in supine and standing positions among 2 cohorts composed of 10 controls and 10 total hip arthroplasty patients. Differences in baseline peak venous velocity (PVV), PVV with each PCD, and delta PVV with each PCD were assessed. A multivariate analysis was performed to examine differences between cohorts, devices, and position. RESULTS: In both positions, the SPCD demonstrated a larger change in PVV when compared to the PPCD (P < .001). The total hip arthroplasty group had a greater delta PVV while standing when considering both PCDs together (P < .001). When considering both cohorts, delta PVV was greater while standing, only when the SPCD was used (P < .001). There was no difference between standing and supine positions when the PPCD was used. CONCLUSION: The SPCD demonstrated a greater capacity to increase PPV in the supine and standing positions. The SPCD generated greater values of PVV and delta PVV in the standing position. Although these results demonstrate a difference between devices, it is important to establish the PVV necessary to prevent VTE before one is considered more effective.