UMEM Educational Pearls - By Kerith Joseph

Study Overview

Title: Identification of Knee Effusions With Ultrasound: A Comparison of Three Methods
Design: Prospective cohort study
Setting: Outpatient orthopaedic clinic
Participants: 52 adults (104 knees), including 57 painful knees

Objective

Determine whether two simple dynamic techniques improve ultrasound detection of suprapatellar knee effusions compared with static scanning.

Ultrasound Methods Compared

Static scanning: Patient relaxed; standard long- and short-axis views.

Parapatellar pressure (Method 1): Examiner compresses medial and lateral parapatellar recesses during scanning.

Quadriceps contraction (Method 2): Patient actively contracts quadriceps during scanning.

Outcome Measure

Presence of fluid in the suprapatellar recess (graded using a standardized ultrasound effusion scale).

Key Results

Effusions detected:

Static scanning: 45

Parapatellar pressure: 58

Quadriceps contraction: 77

Comparative performance:

Quadriceps contraction was superior to parapatellar pressure for detecting:

All effusions (PR 1.33; P < 0.001)

Painful knees (PR 1.24; P = 0.036)

Painless knees (PR 1.50; P = 0.006)

Both dynamic methods outperformed static scanning.

Additional detection beyond static scanning:

Parapatellar pressure: +16.9% of knees

Quadriceps contraction: +54.2% of knees

Reliability (Inter-rater Agreement)

Static scanning: ? = 0.771

Parapatellar pressure: ? = 0.686

Quadriceps contraction: ? = 0.846

All methods showed high reliability, with quadriceps contraction highest.

Conclusions

Both parapatellar pressure and patient-initiated quadriceps contraction significantly improve ultrasound detection of suprapatellar knee effusions.

Quadriceps contraction is the most effective method, especially for small or occult (grade 1) effusions.

Clinically Oriented Takeaway

A single-view posterior POCUS can reliably identify anterior shoulder dislocation using the **Glenohumeral Separation Distance (GhSD)**—a simple measurement of the posterior alignment of the humeral head and glenoid.

How to Use It

Place a linear probe transversely on the posterior shoulder.

Identify the most posterior aspect of the humeral head and glenoid.

Measure the vertical offset (GhSD):

GhSD > 0 cm ? Normal alignment

GhSD < 0 cm ? Anterior dislocation

GhSD = 0 cm ? Borderline; treat as suspicious

Clinical Implications

Even minimally trained operators achieved 100% sensitivity and specificity in detecting anterior dislocation using this method.

POCUS can:

Enable rapid diagnosis when radiography is delayed.

Confirm reduction immediately at bedside, especially valuable when sedation is used.

Potentially reduce ED length of stay and radiation exposure.

Limitations to Consider

Not validated for posterior dislocations.

Does not assess associated injuries (fractures, Hill-Sachs, Bankart lesions).

Findings based on novice sonographers; performance among clinicians likely equal or better but still needs broader validation.

Single-center, small convenience sample.

No posterior dislocations occurred; technique not validated for them.

Novice sonographers could not be fully blinded to shoulder appearance.

Summary

Objective:
The study aimed to determine how a brief educational intervention could enable emergency medicine (EM) residents to use point-of-care ultrasound (POCUS) effectively to diagnose and manage shoulder dislocations in the emergency department (ED).

Methods:

Conducted at an academic teaching hospital in Miami, Florida.

Twenty EM residents (PGY1–PGY4) with no prior shoulder ultrasound training participated.

Residents received <1 hour of in-service training, including a short lecture, video instruction, and hands-on practice using a Sonosite M-Turbo ultrasound device.

Over one year (2016–2017), residents prospectively enrolled 78 adult patients with suspected shoulder dislocation.

POCUS findings were compared with x-rays (the gold standard) for accuracy.

Time to diagnosis and reduction confirmation were recorded.

Results:

55 of 78 patients were diagnosed with dislocation; 53 anterior, 1 posterior, 1 inferior.

POCUS achieved 100% sensitivity and specificity for diagnosing and confirming successful reductions compared to x-ray.

Ultrasound results were available ~22 minutes faster for diagnosis and ~27 minutes faster for reduction confirmation than x-rays (p < 0.0001).

Residents across all training years performed equally well.

POCUS also identified 14 fractures (12 confirmed by x-ray, 2 seen only on ultrasound).

Discussion:

A short educational session enabled residents to accurately use POCUS for shoulder dislocation diagnosis and management.

POCUS reduced diagnostic time, avoided radiation exposure, and may improve ED workflow and patient comfort.

Findings support including shoulder ultrasound as a core component of EM training, filling a current gap in national ultrasound education guidelines.

Limitations:

Convenience sample and single-center design.

Some selection bias and inherent limitations of POCUS-based studies.

Conclusion:

Emergency medicine residents can learn to diagnose and manage shoulder dislocations with excellent accuracy after brief ultrasound training. POCUS should be integrated into EM residency curricula as a core skill for musculoskeletal emergencies.

Summary:
This study evaluated whether the line-of-sight approach improves the speed and accuracy of ultrasound-guided needle placement into the subdeltoid bursa among novice operators, compared to the side approach. A secondary aim was to assess the usefulness of the APPLES mnemonic (Angle, Position, Perpendicular, Line up, Entry, Sweep) as a teaching aid.

Methods:
Medical students and residents were randomized to perform the procedure using both approaches in a crossover design. Two blinded reviewers measured procedure time, and participants completed a survey on their preferences and perceptions of APPLES. Statistical tests (paired t test, McNemar test) compared performance time and accuracy.

Results:

The line-of-sight approach significantly reduced procedure time (mean 14.4 s vs. 18.6 s; P = .00029).

Participants were more likely to hit the target within 30 s using the line-of-sight approach (P = .035).

72.7% preferred the line-of-sight approach.

88.2% found the APPLES mnemonic helpful.

Conclusions:
The operator’s positioning plays a key role in ultrasound-guided procedures. The line-of-sight approach improves both speed and accuracy for novice users, and the APPLES mnemonic is a valuable educational tool for teaching these techniques.

Kerith Joseph MD, RMSK

Clinical Associate Professor

University of Maryland School of Medicine

Baltimore Veterans Affairs Medical Center, Emergency Department