Case 65: Knee Pain

Colleen Sweeney, Akash Desai

A 55-year-old female with no pertinent past medical or surgical history was brought in by ambulance after a bicycle accident with left knee pain. She was unhelmeted while riding a bicycle going 10mph when she collided into an e-bike. Her left knee was caught in her handlebars; she denied head trauma and had no LOC.

Vitals: BP 168/120, HR 70, T 96.0F, RR 22, SpO2 95% on RA, BMI 24.41

Physical Exam:
General/Neuro: alert, in acute distress, diaphoretic
HEENT: normocephalic, atraumatic, EOMI
CV: normal rate
Resp: tachypneic
Abdomen: flat, soft, no tenderness
MSK: RLE normal
L knee: +swelling, +deformity. Skin intact, small ecchymosis to left lateral knee. Knee diffusely tender to palpation. Sensation intact to light touch throughout. Palpable popliteal, PT, and DP pulses. Able to wiggle toes. Compartments compressible. Patient unable to tolerate any movement of L knee secondary to pain.
L lower leg: +swelling from knee distally, no lacerations
L ankle/foot: normal pulse, sensation intact to light touch throughout

Radiographs were indicated and initially attempted at bedside, however were unsuccessful as the patient was unable to tolerate the pain. Radiography was delayed until two hours due to pain management and census. In the interim, a POCUS was performed

Figure 1. Transverse view of infrapatellar lipohemarthrosis.

Figure 2. Longitudinal view of infrapatellar lipohemarthrosis.

Figure 3. Longitudinal view of tibia with cortical break (arrow).

Xray findings: "Acute, comminuted, displaced proximal tibial fracture extending to the lateral and central tibial plateau. Acute, mildly displaced and impacted fibular neck fracture. No fracture or malalignment of the left ankle. "

The patient was admitted to the trauma surgery service. The next day, she underwent a left knee spanning external fixator for stabilization of the tibial plateau fracture. One week later, she had an ORIF for long-term fixation of the fracture as well as a hamstring tendon repair.

Discussion

POCUS is increasingly utilized in acute musculoskeletal trauma. The patient’s gross knee deformity after a traumatic event led to POCUS utilization to provide rapid clinical guidance. In this patient, ultrasound was complete half an hour prior to the first attempt at radiographs and over 2 hours prior to their completion, thus proving useful in differentiating the severity of a patient’s injury during prolonged wait times and facilitating early orthopedic surgery consultation.

Ultrasound, though not a primary diagnostic modality for acute fractures, offers sensitivity of 87% and specificity of 70% for proximal tibial fractures specifically in cadaveric models [3]. In Figure 3, the cortical break visible on the left side of the image corresponds to the proximal tibial fracture seen on X-ray.

Figures 1 and 2 both demonstrate lipohemarthrosis. The presence of hemarthrosis, rather than a simple joint effusion, raises the suspicion for an intra-articular injury or fracture, with ultrasound demonstrating a sensitivity of 90% and specificity of 86% for this finding [2]. When lipohemarthrosis is identified—most clearly visualized in Figure 2 as hypoechoic fat “bubbles” originating from the bone marrow—it is even more indicative of an intra-articular fracture, carrying 97% sensitivity and 100% specificity for such fractures [4]. In its early stage, lipohemarthrosis appears as scattered fat globules, which later settle into the characteristic triple-layer pattern of fat, serum, and blood products [5]. Recognition of hemarthrosis or lipohemarthrosis on ultrasound may help risk-stratify patients for joint aspiration, potentially reducing unnecessary aspirations and associated infection risk.

The presence of lipohemarthrosis is highly suggestive of a distal femur or proximal tibial fracture. Recognizing these findings early allows clinicians to maintain a high index of suspicion for periarticular fracture prior to radiographic confirmation, enabling prompt immobilization, consultation, and fracture management. This early identification facilitates more efficient triage and throughput in the ED and underscores POCUS as a worthwhile adjunct in knee trauma in addition to traditional imaging such as X-ray, CT, and MRI [6].

References:

Stannard JP, Lopez R, Volgas D. Soft tissue injury of the knee after tibial plateau fractures. J Knee Surg. 2010;23(4):187-192. doi:10.1055/s-0030-1268694
Taljanovic MS, Chang EY, Ha AS, et al. ACR appropriateness criteria® acute trauma to the knee. Journal of the American College of Radiology. 2020;17(5). doi:10.1016/j.jacr.2020.01.041 
Demers G, Migliore S, Bennett DR, et al. Ultrasound evaluation of cranial and long bone fractures in a cadaver model. Mil Med. 2012;177(7):836-839. doi:10.7205/milmed-d-11-00407
Bonnefoy, O., Diris, B., Moinard, M. et al. Acute knee trauma: role of ultrasound. Eur Radiol 16, 2542–2548 (2006). Doi:10.1007/s00330-006-0319-x
Levrini G, Reggiani G, Vacondio R, Zompatori M, Nicoli F. Post-traumatic knee lipohemarthrosis: Temporal evolution with progressive separation of the three layers of the joint effusion by ultrasonography and computed tomography. European Journal of Radiology Extra. 2006;60(1):37-41. doi:10.1016/j.ejrex.2006.06.011 
De Maeseneer M, Marcelis S, Boulet C, et al. Ultrasound of the knee with emphasis on the detailed anatomy of anterior, medial, and lateral structures. Skeletal Radiol. 2014;43(8):1025-1039. doi:10.1007/s00256-014-1841-6

March 10, 2026March 10, 2026

Case 63: Point-of-Care Ultrasound in Inferior Glenohumeral Dislocation (Luxatio Erecta)

Makhlouf Bannoud, Colleen Campbell

A 22-year-old male with no significant past medical history presented to the emergency department with right shoulder pain and visible deformity after a surfing injury. He reported that a wave forcefully pulled his surfboard while he was holding on, followed by an audible “pop.” He denied head trauma, distal numbness, weakness, or additional injuries.

Vitals: BP 151/81 | HR 104 | RR 27 | Temp 97.8°F (36.6°C) | SpO₂ 93%

On exam, the patient was in acute discomfort but alert and oriented. The right upper extremity was held in abduction with visible deformity and inferior displacement of the humeral head. Distal neurovascular exam demonstrated 2+ radial pulse, intact sensation in the axillary, median, radial, and ulnar distributions, and full motor strength in the hand.

Point-of-care ultrasound (POCUS) of the right shoulder was performed prior to radiography to evaluate the glenohumeral joint. Ultrasound demonstrated inferior displacement of the humeral head relative to the glenoid fossa, consistent with inferior glenohumeral dislocation (Figure 1). No obvious joint effusion or cortical step-offsuggestive of displaced fracture was visualized.

Figure 1: Inferior shoulder dislocation with humerus outside the glenoid fossa.

Ultrasound guidance was then used to perform an intra-articular anesthetic injection for analgesia prior to reduction (Figure 2).

Figure 2: Ultrasound-guided joint injection.

Moderate procedural sedation with propofol was subsequently administered. Closed reduction was performed successfully.

Post-reduction POCUS demonstrated restoration of normal alignment between the humeral head and glenoid (Figure 3).

Figure 2: Post-reduction ultrasound.

Follow-up radiographs confirmed interval reduction and revealed a Hill-Sachs deformity without definitive osseous Bankart lesion. Repeat neurovascular examination remained intact. The patient was placed in a sling and discharged with close orthopedic follow-up.

Discussion

Inferior glenohumeral dislocation, or luxatio erecta, accounts for less than 1% of shoulder dislocations [1]. The classic mechanism involves hyperabduction, driving the humeral head inferior to the glenoid fossa. Patients typically present with the arm fixed in abduction and inability to adduct the limb.

Although radiographs remain standard for definitive diagnosis, point-of-care ultrasound has emerged as a reliable adjunct for rapid diagnosis of shoulder dislocation. Multiple studies have demonstrated high sensitivity and specificity approaching 100% for identifying glenohumeral dislocation [2]. Ultrasound allows dynamic assessment without radiation and can expedite care in high-volume emergency settings.

The posterior transverse view is most commonly used, with the probe placed over the scapular spine to visualize the glenoid and humeral head relationship. In normal alignment, the humeral head appears centered over the glenoid. In inferior dislocation, the humeral head is displaced caudally relative to the glenoid, as demonstrated in this case.

POCUS also facilitates ultrasound-guided intra-articular anesthetic injection. Compared to landmark-based techniques, ultrasound guidance improves accuracy of joint entry and reduces complications [3]. Intra-articular lidocaine has been shown to be comparable to intravenous sedation in facilitating reduction, with shorter ED length of stay and fewer adverse events [4].

In this case, ultrasound-guided anesthetic injection was used as adjunctive analgesia prior to procedural sedation. Vascular injury, although rare, may involve the axillary artery. For this reason, careful pre- and post-reduction neurovascular examination is essential.

Associated injuries are common and include Hill-Sachs deformity, greater tuberosity fracture, rotator cuffinjury, and labral tears. [5] Post-reduction imaging in this case demonstrated a Hill-Sachs lesion, which may predispose young active patients to recurrent instability depending on lesion size and engagement.

This case highlights the expanding role of point-of-care ultrasound in musculoskeletal emergencies. POCUS enabled rapid confirmation of inferior glenohumeral dislocation, guided intra-articular anesthetic injection, and verified successful reduction prior to radiographic confirmation. When integrated thoughtfully into clinical workflow, ultrasound enhances procedural safety, diagnostic efficiency, and patient comfort in the management of shoulder dislocation.

References:

[1] StatPearls. (2023). Inferior shoulder dislocations. In StatPearls [Internet]. StatPearls Publishing. Retrieved October 2025, from https://www.ncbi.nlm.nih.gov/books/NBK448196/

[2] Gottlieb, M., Holladay, D., & Peksa, G. D. (2019). Point-of-care ultrasound for the diagnosis of shoulder dislocation: a systematic review and meta-analysis. The American Journal of Emergency Medicine, 37(4), 757-761.

[3] Aly, A. R., Rajasekaran, S., & Ashworth, N. (2015). Ultrasound-guided shoulder girdle injections are more accurate and more effective than landmark-guided injections: a systematic review and meta-analysis. British journal of sports medicine, 49(16), 1042-1049.

[4] Sithamparapillai, A., Grewal, K., Thompson, C., Walsh, C., & McLeod, S. (2022). Intra-articular lidocaine versus intravenous sedation for closed reduction of acute anterior shoulder dislocation in the emergency department: a systematic review and meta-analysis. Canadian Journal of Emergency Medicine, 24(8), 809-819.

[5] Ostermann, R. C., Joestl, J., Hofbauer, M., Fialka, C., Schanda, J. E., Gruber, M., ... & Tiefenboeck, T. M. (2022). Associated pathologies following luxatio erecta humeri: a retrospective analysis of 38 cases. Journal of Clinical Medicine, 11(2), 453.

[6] Flinders, A., & Seif, D. (2016). Point-of-Care Ultrasound in Diagnosis and Treatment of Luxatio Erecta (Inferior Shoulder Dislocation). Journal of Medical Ultrasound, 24(2), 70-73

May 15, 2023August 2, 2023

Case 30: Ultrasound-Guided Extraction of a Foreign Body

A 53-year-old homeless alcoholic female presented to the emergency department with a chief complaint of localized left lower quadrant abdominal pain secondary to a possible gunshot wound. She was unclear but stated she thinks some boys in a gang fired at her two days prior with a possible BB gun. Pertinent medical history included psychiatric history, morbid obesity (BMI>40), chronic alcohol abuse, sepsis and hypoxemic respiratory failure. The patient was clinically intoxicated upon arrival and therefore history was of limited accuracy.

Upon arrival, patient appeared stable and vitals were as follows:

BP: 121/63 | HR: 73 | RR: 18 | T: 98.4 | Sp02: 98% on RA

Physical examination revealed a 10x10 cm area of ecchymosis with a central penetrating wound about 2mm, to the left lower quadrant. The patient was tender to palpation around the affected area but there was no significant warmth or erythema to suggest infection. No palpable foreign bodies were identified. There were no signs of peritonitis: the remainder of the abdominal examination was benign and patient had active bowel sounds. She denied vomiting, hematuria, hematochezia, and melena. She also denied shortness of breath, chest pain, and back pain.

To evaluate the wound for the presence of foreign bodies and for depth of penetration, bedside ultrasound was obtained. What do you see, and how would this change your patient management?

Figure 1: Wound prior to foreign body exploration.

Figure 2: A hyperechoic object with reverberation artifacts and shadow seen at 1cm.

Figure 3: Removal of FB under US guidance using curved hemostats.

Figure 4: Extracted pellet.

Answer and Learning Points

Answer:

Figure 4: Labeled ultrasound image shows hyperechoic object and reverberation artifact with shadow.

In these scans, an echogenic foreign body can be observed 1 cm below the epidermis with associated reverberation and mirror artifact. Using ultrasound guidance, a curved hemostat was used to remove the foreign body after local anesthetic injection. Upon contact with the forceps, the foreign body can be seen fluctuating in position. A rounded edge on the foreign body can be seen on the image. Importantly, we clearly identified the peritoneal line to be > 4cm deeper than the foreign body and were able to safely determine the foreign body location to be significantly more superficial to the abdominal wall musculature.

Discussion

Soft tissue foreign bodies (FB’s) are a common reason for Emergency Department visits, with open wounds producing 4,171,000 visits to United States Emergency Departments in 2020 [1]. However, retained foreign bodies account for 7-15% of cases, particularly those involving the extremities. A granulomatous tissue response commonly known as an FB reaction results as the immune system attempts to isolate the FB from the host [2]. This can lead to serious adverse complications including soft tissue inflammation and infection. The most commonly retained FB materials are metal, glass and wood. Glass accounts for half of missed FB’s on physical examination and radiographs. Although essential, a physician-performed clinical history, physical examination, and wound exploration are not sufficient to exclude a FB from differentials [2]. Thus, imaging plays an essential role in improving patient outcomes that present with FB’s.

MRI is not a suitable imaging modality, as metallic contents may have hazardous movements due to the magnetic field. Computed tomography (CT) and ultrasound sonography (US) are the most effective imaging modalities. CT and US have similar sensitivity in identifying high-density objects such as stone, metal and glass [3]. Low-density foreign objects such as plastic and wood are remarkably difficult to see in techniques other than US, regardless of superficial or deep impaction. For example, radiographic images have a sensitivity of 7.4% for wood [3,4]. Sensitivity of ultrasound for FB is 80% on average, and it carries a specificity of 85%, with metals being much higher due to noticeable reverberation, and wood is more difficult to detect. However, the sensitivity of US to identify foreign bodies in soft tissues begins to decrease as the depth of the foreign body surpasses 4cm [4].

US provides a unique advantage to foreign body detection as it can provide instantaneous and simultaneous visualization of foreign bodies during extraction procedures with minimal risk and no exposure to radiation. In a study of pediatric patients presenting with an FB, sonography performed by EM physicians provided an overall sensitivity of 67% and a specificity of 96.6% [4]. US is inexpensive and provides real-time visualization, however the quality of US images is operator dependent [5].

Material of FB	Ultrasound finding
Stone	Hyperechoic area with pronounced acoustic shadow
Metal	Hyperechoic area with reverberation artifacts
Glass	Hyperechoic area with comet tails; less visible than metal
Plastic	Hyperechoic area with slight acoustic shadow
Wood	Hypoechoic area with “halo”

Table 1: A List of FB Materials and the Expected US Findings [3].

To perform this technique, scan use the linear probe in the area of the suspected location of the FB. The FB can be identified by characteristic reverberation or acoustic shadowing, with additional indications being signs of infection, edema, or interruption of the fascial planes. Position the probe so that the FB is visualized in the center of the screen, and mark this area with a surgical pen. Rotate the probe 90 degrees and ensure the FB is in the middle of the US screen. Then mark this area with a surgical pen. Where these markings cross should give you the exact location of the FB such that incision and probing with forceps will result in effective removal of the FB.

Removing foreign bodies is one of the least favorite procedures in the Emergency Department due to it’s difficulty and low success rates. Bedside ultrasound is easily performed and is a useful adjunct in the accurate identification of foreign bodies and also can provide real-time guidance in foreign body removal.

References

1) Cairns C, Kang K. National Hospital Ambulatory Medical Care Survey: 2020 emergency department summary tables. DOI: https://dx.doi.org/10.15620/cdc:121911.

2) Carneiro BC, Cruz IAN, Chemin RN, et al. Multimodality Imaging of Foreign Bodies: New Insights into Old Challenges. Radiographics. 2020;40(7):1965-1986. doi:10.1148/rg.2020200061

3) Haghnegahdar A, Shakibafard A, Khosravifard N. Comparison between Computed Tomography and Ultrasonography in Detecting Foreign Bodies Regarding Their Composition and Depth: An In Vitro Study. J Dent (Shiraz). 2016;17(3):177-184.

4) Davis J, Czerniski B, Au A, Adhikari S, Farrell I, Fields JM. Diagnostic Accuracy of Ultrasonography in Retained Soft Tissue Foreign Bodies: A Systematic Review and Meta-analysis. Acad Emerg Med. 2015;22(7):777-787. doi:10.1111/acem.12714

5) Rupert J, Honeycutt JD, Odom MR. Foreign Bodies in the Skin: Evaluation and Management. Am Fam Physician. 2020;101(12):740-747.

This post was written by Cameron Olandt, Rachna Subramony, MD, Skyler Sloane, and Colleen Campbell, MD.

September 1, 2022September 1, 2022

Case 28: Nah-bscess

A 35 year old male with a history of IV drug use and HIV on ART presents to the emergency department with pain and redness of his left upper extremity for a few days. He denies systemic symptoms or prior history of abscess.

Vitals: Temp 98.5, HR 93, BP 122/75, RR20

Physical Exam: Notable for a large, well circumscribed area of induration, erythema, warmth, and tenderness on the left upper arm. Distal to the lesion, there is intact cap refill and 2+ radial pulse.

A bedside ultrasound was performed. What do you see?

Answer and Learning Points

Answer:

Image 1 is a transverse view of the LUE and demonstrates cobblestoning in the subcutaneous tissue which is suggestive of cellulitis. There is no fluid tracking on the fascial planes, fascial thickening, hyperechoic gas or dirty shadowing to suggest necrotizing fasciitis.

Image 1 also demonstrates a well-circumscribed, anechoic fluid collection concerning for an abscess. However, the lumen-like and well-demarcated appearance deep to the area of cobblestoning also suggests a blood vessel, and so we imaged it with color and pulse-wave doppler.

Image 2 use color doppler and demonstrates turbulent flow within the fluid collection. Superficial and medial to the fluid collection, a vessel can be appreciated with flow towards the ultrasound probe.

Image 3 and 4 use pulse wave doppler and demonstrate areas of both pulsatile and continuous flow in various parts of this structure.

Image 5 demonstrates continuity between a distal pulsatile vessel and the proximal fluid collection. The fluid collection likely represents an arterial aneurysm or arteriovenous fistula, as opposed to an abscess. Taking into consideration the patients history of IV drug use, trauma from repeated injections may have created abnormal structures within the patient’s vasculature.

Conclusion and Learning Points:

1. When there is concern for cellulitis, POCUS is a useful tool to quickly evaluate for drainable fluid collections, as well as to evaluate for necrotizing fasciitis.

2. When evaluating a possible abscess, it is important to confirm that the collection has no pusatility or flow before attempting drainage.

References

1. Bystritsky R, Chambers H. Cellulitis and Soft Tissue Infections. Ann Intern Med. 2018 Feb 6;168(3):ITC17-ITC32. doi: 10.7326/AITC201802060. Erratum in: Ann Intern Med. 2020 May 19;172(10):708. PMID: 29404597.

2. Paz Maya S, Dualde Beltrán D, Lemercier P, Leiva-Salinas C. Necrotizing fasciitis: an urgent diagnosis. Skeletal Radiol. 2014 May;43(5):577-89. doi: 10.1007/s00256-013-1813-2. Epub 2014 Jan 29. PMID: 24469151.

This post was written by Jeff Hendel, MS4 and Ben Liotta, MD, with further editing by Sukh Singh, MD.

July 22, 2020May 4, 2021

Can Fluid Accumulation on Ultrasound Diagnose Necrotizing Fasciitis?

Background

Necrotizing fasciitis (NF) is rapidly progressing, severe soft tissue infection with a mortality rate of 19.3% with treatment and significantly higher without treatment (1). Early diagnosis is essential to prompt surgical intervention and reduce morbidity and mortality. However, treatment can often be delayed because no laboratory or imaging test can definitively diagnose NF. Contrast-enhanced CT shows the best accuracy, but again is not perfect and can be difficult to obtain in unstable patients. MRI is similarly accurate, but even less feasible in the Emergency Department. Ultimately, it remains a surgical diagnosis.

Ultrasonography is a rapid, bedside, and non-invasive tool that has potential to accelerate assessment of patient with clinical suspicion for NF. There are ultrasonographic findings associated with NF diagnosis, including irregularity or thickening of deep fascia, subcutaneous emphysema, and fluid accumulation along the deep fascial plane (2-13). Considering this condition’s rapid progression, ultrasonography may enable physicians to quickly gauge disease severity and triage accordingly, prompting earlier surgery and bettering patient outcomes.

The Relationship Between Fluid Accumulation in Ultrasonography and Diagnosis and Prognosis of Patients with Necrotizing Fasciitis

Clinical Question

What is the relationship between ultrasonographic finding of fluid accumulation along the deep fascia and diagnosis and prognosis of necrotizing fasciitis?

What ultrasonographic findings are significantly different between NF patients and non-NF patients?

What is the ultrasonographic-detected depth of fluid accumulation along the deep fascia that offers the greatest accuracy to diagnosis of NF?

Is there a difference in the prognosis between NF patients with fluid accumulation compared to NF patients without fluid accumulation?

Methods & Study Design

• Design

Retrospective study with prospective enrollment

• Population

This study was conducted at Chang Gung Memorial Hospital, a suburban academic tertiary care hospital.

Inclusion criteria: patients who visited the ED from February 2015 – November 2016 with clinical suspicion of NF of limbs based on symptoms and clinical signs (severe pain out of proportion, skin findings, rapid progression, crepitus, skin bullae, necrosis, or ecchymosis).

NF group: discharge diagnosis of NF, confirmed by pathology report showing necrosis after surgical intervention

Non-NF group: did not have surgical intervention or whose pathology report did not support NF diagnosis

Exclusion criteria: patients with ED visits between 24:00 – 7:00, non-lesion side also has fluid accumulation, age <18yo, prior antibiotics or debridement, lesions involving trunk area

• Intervention

Ultrasonographic exam within 1 hour after ED arrival completed by one of three experienced emergency physicians who received an 8-hour basic and soft-tissue ultrasonographic training before the study

Orthopedic consult for surgical opinion

• Outcomes

Diagnostic markers: irregularity or thickening of deep fascia, fluid accumulation, subcutaneous emphysema, subcutaneous cobblestone
Reasonable cutoff value of fluid accumulation along deep fascial plane for diagnosing NF according to receiving operating characteristic (ROC) curve
Prognostic markers: length of stay (LOS) in hospital, mortality, amputations, number of operations

Results

Ultrasound finding of fluid accumulation and irregular or thickened fascial layer were significantly different between NF and non-NF groups. All patients who had subcutaneous emphysema were in the NF group.

The best cutoff point of fluid accumulation to diagnose NF was 2mm, which had the best accuracy (72.7%), with sensitivity of 75%, a specificity of 70.2%, a positive predictive value of 71.7% and a negative predictive value of 72.7%.

NF patients with fluid accumulation had longer length of stay than NF patients without fluid accumulation (average: 39 days vs. 23 days). Number of operations were not significantly different between NF patients with and without fluid accumulation. All NF patients who had an amputation or died had fluid accumulation.

Overall mortality between NF and non-NF groups showed no significant difference.

Strength & Limitations

Strengths

Sample size was larger than other studies investigating ultrasonographic findings for NF diagnosis.
Study had a comparator groups with clear definitions (NF vs. non-NF).
Ultrasound training was standardized and assessed with inter-rater reliability between three emergency physicians as 100%.

Limitations

Small, imbalanced sample of NF patients for sensitivity and specificity analysis of fluid accumulation for amputation and mortality.
Study excluded patients with truncal soft tissue infections.
Study excluded patients with prior antibiotics or debridement, which may have been NF patients with higher severity and worse prognosis.
Patient population were from south Taiwan exclusively.
NF patients had higher prevalence of specific co-morbidities (diabetes mellitus, liver cirrhosis, and alcohol use disorder), which could be confounding.

Authors Conclusion

“The ultrasonographic finding of fluid accumulation along the deep fascia with a cutoff point of more than 2 mm of depth may aid in diagnosing NF. For the prognosis of NF, when fluid accumulation was present along deep fascia on ultrasound, patients with NF had longer lengths of hospital stays and were at risk of amputation or mortality. Ultrasonography is a point-of-care imaging tool that facilitates the diagnosis and prognosis of NF.” (14)

Our Conclusion

Consistent with prior studies and case reports (2-13), this study supports the role of ultrasound in the diagnosis of NF. Trained emergency physicians were able to successfully use ultrasound to detect significant imaging differences in NF patients, including fascial irregularity and deep fascial fluid accumulation. In comparison to Yen et al., this study suggests an even lower cutoff point of fluid accumulation along the deep fascia (2mm vs 4mm) for the highest diagnostic accuracy. We would caution that the finding of "fluid accumulation" was somewhat difficult to interpret in their study.

Further studies with larger sample sizes need to be completed. However, with the diagnostic and prognostic trends seen in this study, ultrasound should be considered as a timely, efficient imaging modality that can help identify patients with clinical suspicion of NF and accelerate OR intervention.

The Bottom Line

Ultrasound is a viable imaging modality for patients with clinical suspicion of NF that could potentially expedite surgical intervention, though imaging findings may not be as easy to interpret as the authors lay out.

Authors

This post was written by Caresse Vuong, Charles Murchison MD and Amir Aminlari MD.

References

Khamnuan P, Chongruksut W, Jearwattanakanok K, Patumanond J, Yodluangfun S, Tantraworasin A. Necrotizing fasciitis: Risk factors of mortality. Risk Manag Healthc Policy 2015;8:1–7.
Castleberg E, Jenson N, Am Dinh V. Diagnosis of necrotizing fasciitis with bedside ultrasound: The STAFF exam. West J Emerg Med 2014;15:111–113.
Tsai CC, Lai CS, Yu ML, Chou CK, Lin SD. Early diagnosis of necrotizing fasciitis by utilization of ultrasonography. Kaohsiung J Med Sci 1996;12:235–240.
Wronski M, Slodkowski M, Cebulski W, Karkocha D, Krasnodebski IW. Necrotizing fasciitis: Early sonographic diagnosis. J Clin Ultrasound 2011;39:236–239.
Yen ZS, Wang HP, Ma HM, Chen SC, Chen WJ. Ultrasonographic screening of clinically-suspected necrotizing fasciitis. Acad Emerg Med 2002;9:1448–1451.
Bernardi, Emanuele, Antonello Iacobucci, Letizia Barutta, Elisa Pizzolato, Virna Olocco, and Bruno Tartaglino. “A-Lines in Necrotizing Fasciitis of the Lower Limb.” Journal of Ultrasound in Medicine 33, no. 11 (2014): 2044–46.
Chao, H. C., M. S. Kong, and T. Y. Lin. “Diagnosis of Necrotizing Fasciitis in Children.” Journal of Ultrasound in Medicine: Official Journal of the American Institute of Ultrasound in Medicine 18, no. 4 (April 1999): 277–81.
Hosek, William T., and Timothy C. Laeger. “Early Diagnosis of Necrotizing Fasciitis with Soft Tissue Ultrasound.” Academic Emergency Medicine 16, no. 10 (2009): 1033–1033.
Oelze, Lindsay, Stanley Wu, and Jennifer Carnell. “Emergency Ultrasonography for the Early Diagnosis of Necrotizing Fasciitis: A Case Series from the ED.” The American Journal of Emergency Medicine 31, no. 3 (March 1, 2013): 632.e5-632.e7.
Kehrl, Thompson. “Point-of-Care Ultrasound Diagnosis of Necrotizing Fasciitis Missed by Computed Tomography and Magnetic Resonance Imaging.” The Journal of Emergency Medicine 47, no. 2 (August 2014): 172–75.
Shyy, William, Roneesha S. Knight, Ruth Goldstein, Eric D. Isaacs, and Nathan A. Teismann. “Sonographic Findings in Necrotizing Fasciitis.” Journal of Ultrasound in Medicine 35, no. 10 (2016): 2273–77.
Hanif, Muhammad A., and Michael J. Bradley. “Sonographic Findings of Necrotizing Fasciitis in the Breast.” Journal of Clinical Ultrasound: JCU 36, no. 8 (October 2008): 517–19.
Valle Alonso, Joaquín, Ganapathiram Lakshmanan, and Yasser Saleem. “Use of POCUS Ultrasound in Sepsis, Bedside Diagnosis of Necrotizing Fasciitis.” QJM: An International Journal of Medicine 110, no. 10 (October 1, 2017): 687–88.
Lin, Chun-Nan, Cheng-Ting Hsiao, Chia-Peng Chang, Tsung-Yu Huang, Kuang-Yu Hsiao, Yi-Chuan Chen, and Wen-Chih Fann. “The Relationship Between Fluid Accumulation in Ultrasonography and the Diagnosis and Prognosis of Patients with Necrotizing Fasciitis.” Ultrasound in Medicine & Biology 45, no. 7 (2019): 1545–50.

July 8, 2020May 4, 2021

Bedside Ultrasound Identification of Infectious Flexor Tenosynovitis in the Emergency Department

Background

Infectious flexor tenosynovitis (FTS) is a surgical emergency. If not treated promptly, infectious FTS carries significant morbidity including loss of function of fingers, necrosis of the tendon, and even digit amputation (1).

Infection can be caused in three ways: direct inoculation, contiguous spread, or hematogenous spread, as seen in cases of disseminated gonococcal infection. Tenosynovitis occurs when fluid collects between the visceral and parietal layer of the tendon, the most common location being in the hand and wrist.

Traditionally, diagnosis of infectious FTS is centered on the tetrad known as Kanavel’s signs (swelling of the finger, finger held in partially flexed position, pain on palpation of the flexor tendon, and pain on passive extension of the finger). While Kanavel’s signs are specific for infectious FTD, in a study of 41 participants with infectious FTS, only 54% of patients taken to the operating room (OR) had all of these signs (2). The gold standard of diagnosis remains surgical exploration and drainage. MRI can aid in the diagnosis of FTS, but this is rarely available in the ED. While radiographs may be obtained to look for trauma, osteomyelitis or a foreign body, they offer minimal to no additional benefit in diagnosing infectious FTS.

This article presents a case of a 58-year-old man where point of care ultrasound (POCUS) identified tissue necrosis and fluid along the flexor tendon sheath of the hand, aiding in the rapid diagnosis of FTS, adding to the limited body of literature supporting use of POCUS for early diagnosis of infectious FTS.

Bedside Ultrasound Identification of Infectious Flexor Tenosynovitis in the Emergency Department

Clinical Question

Can point of care ultrasound be used in the emergency department to diagnose infectious FTS?

Methods & Study Design

• Design

Case report.

• Population

58 year old male with hypertension, diabetes and end stage renal disease.

• Intervention

POCUS looking for fluid in flexor tendon sheath. Appropriate technique is shown in the image below, with a linear ultrasound probe placed on the palmar side of the wrist crease. Common findings of FTS are hypoechoic or anechoic fluid surrounding the flexor tendons.

ultrasound flexor tendons — Padrez et al. West J Emerg Med 2015, 16(2)

• Outcomes

Accurate diagnosis of FTS

Results

The physicians found a moderate amount of fluid and echogenic material within the tendon sheath, as noted in the image below. Orthopedics was consulted and patient was started on broad spectrum antibiotics and taken to the operating room. They found extensive pus within the flexor tendon sheath and cultures grew Staph aureus.

ultrasound flexor tenosynovitis — Padrez et al. West J Emerg Med 2015, 16(2)

Strength & Limitations

The POCUS exam the authors describe is practical and useful. This could feasibly be performed by clinicians with relatively little ultrasound training. As mentioned, FTS is a surgical emergency and remains largely a clinical diagnosis, so any modality that helps bring more certainty to the diagnosis, and lead to quicker definitive treatment, is welcome.

It is unclear what the level of ultrasound training was for the physicians who performed this exam. Another note, it may be difficult to distinguish rheumatologic from infectious causes of tenosynovitis using ultrasound, so clinical context is always important. They also mentioned this can only aid in increasing your suspicion for FTS, it cannot be used to rule it out.

Authors Conclusion

POCUS may be an ideal adjunct for the ED physician in the evaluation of a patient with suspected infectious FTS

Our Conclusion

We agree with the authors conclusions that POCUS can be a useful adjunct to clinical exam in diagnosing FTS, with the understanding that POCUS cannot rule out FTS or distinguish rheumatologic from infectious process.

The Bottom Line

POCUS can be a useful adjunct to clinical exam in diagnosing FTS. Use the linear probe and place at the palmar side of the wrist crease, look for hypoechoic or anechoic material around the flexor tendons with possible thickening of the tendon itself.

Authors

This post was written by Betial Asmerom and Amir Aminlari MD. Edited by Charles Murchison MD.

References

Mamane, W. et al. Infectious flexor hand tenosynovitis: State of knowledge. A study of 120 cases. J. Orthop. 15, 701–706 (2018).
Hubbard, D., Joing, S. & Smith, S. W. Pyogenic Flexor Tenosynovitis by Point-of-care Ultrasound in the Emergency Department. Clin. Pract. Cases Emerg. Med. 2, 235–240 (2018).
Padrez et al. Bedsound Ultrasound Identification of Infectious Flexor Tenosynovitis in the Emergency Department. West J Emerg 2015. 16 (2).

November 21, 2018July 21, 2020

Case # 14: Whirlpool swirling, twisting and turning

A 13-year-old male presents to the emergency department with right testicular pain for one-hour duration. The pain began while having a bowel movement. He had no nausea or vomiting. His exam is notable for a high riding right testicle and tenderness to palpation over the right testicle.

Vitals: T: 97.8, HR: 106, BP: 135/79, RR: 16, Sat: 96% on RA

A bedside ultrasound of the testicles is performed. What do you see?

Answer and Learning Points

Answer

These ultrasound images demonstrates limited flow into the right testicle suggestive of testicular torsion. Manual detorsion was performed at the bedside using the “open-the-book” maneuver with subsequent ultrasound demonstrating return of flow to the right testicle. Urology was consulted, and the patient was scheduled for an outpatient orchiopexy.

Learning Points

The acute scrotum is a presentation that requires timely evaluation and management by the emergency physician. Of all causes of acute scrotum, testicular torsion is the diagnosis that requires the most emergent action because of the limited time window of testicular salvageability.¹ Unfortunately, in many clinical settings including urgent cares, clinics, and rural community emergency rooms, it can be challenging to confirm our clinical suspicion in a timely fashion because of the difficulty in obtaining an official scrotal ultrasound. For this reason, POCUS is an important tool for emergency physicians in the diagnosis of patients with acute scrotum.

Ultrasound findings of testicular torsion:

Loss or reduction of color Doppler flow/Spectral Doppler tracings to affected testicle (Must compare to other testicle)

Affected testicle becomes more heterogeneous than other testicle

Adhikari, S. R. (2008). Small parts - Testicular ultrasound. Retrieved from https://www.acep.org/sonoguide/smparts_testicular.html

Thickened, hypoechoic mediastinum^⁵

Prando D. Torsion of the spermatic cord: the main gray-scale and doppler sonographic signs. Abdom Imaging. 2009 Sep-Oct;34(5):648-61. doi: 10.1007/s00261-008-9449-8. Review. PubMed PMID: 18709404.

Whirlpool sign⁶

Author

Marissa Wolfe, MS4; Amir Aminlari, MD, Emergency Ultrasound Fellowship Director at UCSD

References

Mellick LB, Sinex JE, Gibson RW, Mears K. A Systematic Review of Testicle Survival Time After a Torsion Event. Pediatr Emerg Care. 2017 Sep 25. doi: 10.1097/PEC.0000000000001287. [Epub ahead of print] PubMed PMID: 28953100.
Sharp VJ, Kieran K, Arlen AM. Testicular torsion: diagnosis, evaluation, and management. Am Fam Physician. 2013 Dec 15;88(12):835-40. Review. PubMed PMID: 24364548.
Wang S, Scoutt L. Testicular torsion and manual detorsion. Ultrasound Q. 2013 Sep;29(3):261-2. doi: 10.1097/RUQ.0b013e3182a2d129. PubMed PMID: 23945494.
Adhikari, S. R. (2008). Small parts - Testicular ultrasound. Retrieved from https://www.acep.org/sonoguide/smparts_testicular.html
Prando D. Torsion of the spermatic cord: the main gray-scale and doppler sonographic signs. Abdom Imaging. 2009 Sep-Oct;34(5):648-61. doi: 10.1007/s00261-008-9449-8. Review. PubMed PMID: 18709404.
Kalfa N, Veyrac C, Lopez M, Lopez C, Maurel A, Kaselas C, Sibai S, Arena F, Vaos G, Bréaud J, Merrot T, Kalfa D, Khochman I, Mironescu A, Minaev S, Avérous M, Galifer RB. Multicenter assessment of ultrasound of the spermatic cord in children with acute scrotum. J Urol. 2007 Jan;177(1):297-301; discussion 301. PubMed PMID: 17162068.
Vijayaraghavan SB. Sonographic differential diagnosis of acute scrotum: real-time whirlpool sign, a key sign of torsion. J Ultrasound Med. 2006 May;25(5):563-74. PubMed PMID: 16632779.

November 18, 2017July 22, 2020

Case # 10: A Mechanical Issue

A 32 year old male was carrying a heavy pipe overhead with his right arm and slipped falling forward, onto the right side. He notes pain in the right shoulder, worse with any movement. His right arm is flexed and internally rotated for comfort.

Vitals: T 98.6 HR 95 BP 143/91 RR 14 O2 98% on RA

A bedside ultrasound of the right shoulder is performed, what is the next best step in management?

Answer and Learning Points

Answer

Shoulder dislocation reduction. The ultrasound image shows anterior displacement of the humeral head with respect to the glenoid fossa consistent with an anterior shoulder dislocation. A hematoma is also noted within the joint space which is very commonly associated with a traumatic shoulder dislocation.

Ultrasound diagnosis of anterior shoulder dislocation

Learning Points

- Ultrasound is useful for both the initial diagnosis and reduction confirmation of a shoulder dislocation, as well as for intra-articular injection of local anesthetic; however in a traumatic dislocation, an initial x-ray should be obtained to evaluate for any associated fracture.
- To perform the exam, a low frequency curvilinear transducer should be used. The operator should stand behind the patient, on the side of the affected shoulder, and place the ultrasound system directly in front of the patient for easy visualization. The probe should be placed on the posterior aspect of the scapula, parallel and just inferior to the scapular spine. This will allow direct visualization of the glenohumeral joint.
Proper probe placement for evaluation of glenohumeral joint.
- In a normal shoulder the glenoid and humeral head articulate nicely and this can be appreciated on ultrasound with internal and external rotation of the patient's arm, however with dislocation, the humeral head and glenoid will not be aligned. In anterior dislocation, the humeral head will be deep to the glenoid, while in a posterior dislocation, the humeral head will be more superficial to the glenoid.
Normal glenohumeral ultrasound anatomy
- Ultrasound is especially useful to confirm successful shoulder relocation and prevent both a prolonged stay in the emergency department waiting for a post reduction x-ray, as well as re-sedation if this was required for a difficult shoulder reduction.
- Lastly, this same ultrasound view can be used for in-plane needle guidance to provide intra-articular anesthesia using a lateral needle entry approach.
- For a 5 minute video tutorial on ultrasound for shoulder dislocation , click here to watch this excellent video at 5 Minute Sono.

Author

This post was written by Michael Macias, MD, Ultrasound Fellow at UCSD.

References

1. Abbasi S, Molaie H, Hafezimoghadam P, et al. Diagnostic accuracy of ultrasonographic examination in the management of shoulder dislocation in the emergency department. Ann Emerg Med. 2013:1-6.
2. http://www.thepocusatlas.com/musculoskeletal/

October 21, 2017July 22, 2020

Case # 8: A Case of Comparision

A 40 year old male presents to the emergency department with pain to the entire right thumb and wrist for 1 day. He notes that he suffered a small puncture wound to his right thumb 1 day ago while working on his car. The patient has notable circumferential, non-erythematous swelling to his right thumb with tenderness along the flexor tendon. There is also fullness of the dorsum of his wrist. He is holding his fingers flexed and has pain radiating into the wrist with any movement of his fingers or wrist, especially with extension of his fingers.

Vitals: T 98.7 HR 90 BP 132/81 RR 13 O2 98% on RA

A bedside ultrasound is performed, what is the next best step in management?

Normal Left Thumb in Long Axis

Abnormal Right Thumb in Long Axis

Answer and Learning Points

Answer

Empirical antibiotic therapy and orthopedic surgery consultation for infectious flexor tenosynovitis (FTS). The patient meets 4 out of 4 Kanavel's signs and has ultrasound evidence of FTS suggested by a thickened tendon with surrounding anechoic fluid.

Short Axis View of Right 1st Digit demonstrating hypoechoic fluid surrounding tendon.

Learning Points

- FTS is often a clinical diagnosis and examination (Kanavel's signs) is thought to have high sensitivity (91.4-97.1%) but low specificity (51.3-69.2%) for infectious FTS [2]; however a negative exam does not rule it out completely.
  - Kanavel's signs include:
    - Finger held in slight flexion
    - Fusiform swelling
    - Tenderness along the flexor tendon sheath
    - Pain with passive extension of the digit
- FTS is treated with empirical antibiotic therapy as well as early surgical debridement and drainage. Delays in diagnosis can lead to local spread of infection, compartment syndrome and necrosis.
- While there is not high quality evidence describing the use of emergency department point of care ultrasound (POCUS) to diagnose FTS, previous radiographic studies have found ultrasound to be more sensitive than clinical exam for detecting tenosynovitis [3].
- Common ultrasound findings for FTS include:
  - Hypoechoic or anechoic edema or debris within the tendon sheath
  - +/- thickening of the tendon sheath
- The ultrasound examination should be performed using a linear probe, examining the affected tendon (and normal tendon on other hand for comparison), in both the longitudinal and transverse plane.
  - Small rocking or fanning motions should be used to ensure perpendicular orientation of the probe to the tendon to avoid artifact secondary to anisotropy.
- As in all uses of POCUS in the emergency department setting, findings should be interpreted in conjunction with clinical examination and history when evaluating for infectious FTS. We believe POCUS for infectious FTS can be used to increase diagnostic certainty and even expedite care and aggressive treatment however a normal exam should not be used to rule out this diagnosis.

Author

This post was written by Michael Macias, MD, Ultrasound Fellow at UCSD.

References

1. Padrez, K., Bress, J., Johnson, B., & Nagdev, A. (2015). Bedside Ultrasound Identification of Infectious Flexor Tenosynovitis in the Emergency Department. Western Journal Of Emergency Medicine, 16(2), 260-262. doi:10.5811/westjem.2015.1.24474
2. Kennedy CD, e. (2017). Differentiation Between Pyogenic Flexor Tenosynovitis and Other Finger Infections. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 21 October 2017, from https://www.ncbi.nlm.nih.gov/pubmed/28720000
3. Hmamouchi I, Bahiri R, Srifi N, et al. A comparison of ultrasound and clinical examination in the detection of flexor tenosynovitis in early arthritis. BMC Musculoskelet Disord. 2011;12(1):91.