What are the guidelines for using musculoskeletal ultrasound in Physical Medicine and Rehabilitation (PM&R)?

Musculoskeletal Ultrasound in Physical Medicine and Rehabilitation: Guidelines

Core Recommendation

Musculoskeletal ultrasound in PM&R should follow standardized EULAR protocols with specific patient positioning, systematic scanning sequences for each anatomical region, and high-frequency transducers (≥10 MHz) to detect inflammatory lesions, structural damage, and guide interventional procedures. 1

Equipment Requirements

• Use high-frequency transducers of 10 MHz or higher for optimal visualization of superficial structures including tendons, ligaments, and synovial tissues 1
• Select transducers with appropriate footprint size; large footprints are inadequate for small joints like metacarpophalangeal joints due to limited maneuverability 1
• Test equipment capability by visualizing fine structures such as small extensor tendon insertions or pre-Achilles bursa fluid before clinical use 1
• Consider power Doppler imaging to assess blood flow in inflammatory conditions, though this remains under evaluation 1

Standardized Scanning Protocols by Anatomical Region

Shoulder Examination

Patient positioning: 1, 2

• Sitting position with 90° elbow flexion
• Hand in supination resting on patient's thigh
• For dynamic assessment: active/passive external and internal rotation through full range of motion with elbow at 90°

Standard scan sequence: 1

1. Anterior transverse scan in neutral position
2. Anterior transverse scan in maximal internal rotation
3. Anterior longitudinal scan (neutral and maximal internal rotation)
4. Lateral longitudinal scans (neutral and maximal internal rotation)
5. Posterior transverse scan
6. Axillary longitudinal scan with raised arm (most sensitive for small effusions)
7. Acromioclavicular joint scan

Clinical utility: Early detection of tendon changes, bursitis, rotator cuff pathology, and cartilage abnormalities that may be clinically silent despite marked inflammation 1

Elbow Examination

Patient positioning: 1, 3

• Sitting position
• Full extension with supination for ventral scans
• 90° flexion for dorsal scans (hand on hip or thigh with moderate internal rotation)
• Critical: Avoid elbow flexion beyond 90° to prevent ulnar neuropathy 3

Key scanning planes: Ventral longitudinal scans over humeroradial and humeroulnar joints detect early inflammatory lesions; olecranon fossa for synovitis 1

Wrist and Hand Examination

Patient positioning: 1, 3

• Sitting position
• Hand on thigh or examining table
• Dynamic examination with active finger flexion/extension

Standard wrist scans: 1, 3

1. Volar transverse scan (visualizes median nerve at carpal tunnel with 77-79% sensitivity, 94-98% specificity)
2. Volar longitudinal scan
3. Dorsal transverse scans (radial and ulnar)
4. Dorsal longitudinal scans (radial, median, ulnar)

Hand scans: Dorsal longitudinal and transverse scans at metacarpophalangeal joints 1

Clinical applications: High-frequency transducers (≥10 MHz) detect minor synovitic lesions, differentiate synovial from tenosynovial pathology, and assess median nerve morphology in carpal tunnel syndrome 1

Image Acquisition and Documentation Standards

Scanning Technique

• Maintain standardized joint positioning for all anatomical sites to ensure reliability and generalizability of results 1
• Use appropriate transducer manipulation to avoid artifacts; excessive pressure can eliminate synovial hypertrophy or Doppler signal 1
• Document structures in two perpendicular planes for all pathological findings 1

Transducer Orientation Standards 1

• Longitudinal scans: Left side of screen = proximal/cranial; Right side = distal/caudal
• Transverse scans: Left side = medial/ulnar/tibial; Right side = lateral/radial/fibular

Image Documentation

Record all examinations using paper, films, video, laser-printed acetates, optical discs, or digital storage systems with standardized orientation 1

Reporting Requirements for Clinical Studies

When using ultrasound in research or quality improvement, document: 1

• Study objective and design (prospective vs. retrospective)
• Informed consent procedures
• Blinding procedures for sonographers and participants
• Target domain with theoretical ultrasound definitions (e.g., synovitis = synovial hypertrophy plus increased blood flow)
• Elementary lesions with operational definitions (e.g., synovial hypertrophy = increased thickness with hypoechoic appearance)
• Anatomical regions studied with rationale for selection
• Complete scanning procedures: patient position, anatomical region position, surfaces scanned, transducer position, dynamic examination details
• Scoring system type (quantitative, semiquantitative, binary) with score range and meaning

Training and Competency Requirements

• Musculoskeletal ultrasound cannot be learned at conferences over a few days; proper training under experienced investigators is mandatory 1
• Operators must have detailed anatomical knowledge and understanding of basic ultrasound physics 1
• Continuous training and education are essential due to operator-dependent nature of ultrasound 1
• Seek local expertise for hands-on training; national and international societies (EULAR) provide standardized training guidelines 1
• Ultrasound is most valuable when the clinician interprets images in context of clinical history and physical examination, functioning as "the physician's extended finger" 1

Clinical Applications in PM&R Practice

Diagnostic Uses

• Early detection of inflammatory changes in joints, tendons, and bursae before clinical manifestations 4, 5
• Assessment of soft tissue pathology with high-resolution, dynamic, comparative, and repeatable imaging 6
• Evaluation of peripheral nerve pathology (entrapment, enlargement) 3, 7
• Detection of soft tissue foreign bodies (superior to MRI) 7
• Dynamic imaging for pathologies requiring movement assessment 7
• Evaluation of soft tissues adjacent to metal hardware (where MRI is limited) 7

Interventional Guidance

• Ultrasound-guided interventions are more accurate than blind or palpation-guided procedures 6
• Real-time visualization of target structures, needle trajectory, and surrounding vulnerable structures (vessels, nerves) 6
• Non-ionizing, readily available, and relatively low-cost compared to fluoroscopy or CT guidance 6
• Applications include joint aspirations, corticosteroid injections, and other infiltrations 6

Comparison with Other Imaging Modalities

When Ultrasound is Preferred

• Soft tissue foreign bodies 7
• Peripheral nerve evaluation 7
• Pathologies requiring dynamic imaging 7
• Soft tissues adjacent to metal hardware 7
• Real-time procedural guidance 6

When Ultrasound and MRI are Equivalent

• Focal tendon abnormalities 7
• Focal ligament abnormalities 7
• Soft tissue fluid collections 7
• Confirmation of probable benign cysts (Baker's cyst, wrist ganglion) 7

Complementary Role

Musculoskeletal ultrasound should be viewed as complementing MRI rather than competing with it, as each offers unique advantages 7

Common Pitfalls and How to Avoid Them

• Avoid excessive transducer pressure that can compress synovial tissue or eliminate Doppler signal 1
• Do not flex the elbow beyond 90° during examination to prevent ulnar nerve compression 3
• Avoid pressure on the postcondylar groove (ulnar groove) during elbow assessment 3
• Recognize that operator inexperience can lead to incorrect image acquisition and interpretation, potentially causing patient harm through misdiagnosis 1
• Balance clinical examination findings with ultrasound to avoid "seeing what one expects to see"; consider second opinions for scientific analyses 1
• Ensure adequate training before clinical implementation; harm results not from the procedure itself but from operator inexperience 1

Integration into PM&R Practice

Physiatrists increasingly use musculoskeletal ultrasound for: 5, 8

• Assessment of musculoskeletal system architecture and composition
• Evaluation of musculoskeletal changes in dysfunction, pain, or injury
• Echo-guided interventional procedures
• Real-time visual biofeedback for motor control approaches
• Clinical decision-making guidance
• Understanding tissue adaptations to exercise or movement

The technique offers portability, reduced costs, and technological advancements that continue to drive proliferation in clinical medicine 8