DxI Codo y Antebrazo 2026

Main ideas / lessons conveyed

Overarching methodology (clinical reasoning + multimodal imaging)

• Imaging findings (X-ray, ultrasound, MRI, CT) should never be interpreted in isolation.
• The seminar’s guiding principle: “We don’t look at pictures; we make decisions based on biology and function.”
• Imaging must be integrated with:
  • biomechanics
  • the patient’s clinical presentation (symptoms, pain behavior, suspected mechanism)
  • appropriate modality selection to avoid unnecessary risk or delay.

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Five “pillars” of the course (structured outline)

1. Radiological anatomy mastery + pediatric elbow ossification chronology

   • Key tool: “Critoe” mnemonic for the order of appearance of elbow secondary ossification centers.
   • Emphasizes not confusing growth nuclei with fractures.

2. Accurate interpretation of two radiographic reference lines

   • Anterior humeral line
     • In a strict lateral projection (90° flexion), the line on the anterior humeral cortex should cross the middle third of the capitellum.
     • If it passes in front of the middle third → suspect supracondylar fracture (commonly pediatric).
   • Radiocapitellar line
     • The extended radius axis should point to the center of the humeral condyle in any projection.
     • If alignment is lost → suspect radial head dislocation.

3. Use of ACR appropriateness criteria to choose the right test

   • Selecting the wrong study leads to:
     • unnecessary radiation exposure
     • diagnostic delay
   • Test choice is framed as clinical responsibility, not administrative detail.

4. Differentiate structural damage vs clinical pain

   • Especially highlighted for tendon pathology:
     • structural/biological activity and pain intensity are not always synchronized.

5. Therapeutic integration

   • Imaging should guide:
     • rehabilitation planning
     • broader clinical management
   • Goal: connect anatomy + biomechanics + imaging → accurate therapeutic decision.

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Biomechanics concepts used clinically

Elbow stability layers

• Primary (bony) stability
  • Depends on the humeroulnar joint, with the coronoid process as the anterior stop.
  • Coronoid process contributes ~50% of extension stability.
• Secondary (ligamentous) stability
  • Mediated by:
    • LUCL (lateral ulnar collateral ligament)
    • MCL (medial collateral ligament)
    • joint capsule
  • Becomes especially important when bony stability fails (e.g., after coronoid fracture).

“Forearm ring” (radius–ulna–interosseous membrane as a closed circuit)

• Radius, ulna, and the interosseous membrane behave biomechanically like a closed ring.
• Golden rule
  • If you see a displaced radius fracture, actively search for an associated injury on the ulnar side (proximal or distal).
  • Rationale: ring failure on one side almost always compromises the other.

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Modality guidance (what each imaging method is best for)

Four modalities and when they apply

• X-ray
  • First-line in acute trauma / suspected fracture.
  • Mandatory: AP and lateral projections (no exceptions).
• Ultrasound
  • Best for:
    • superficial soft tissues
    • dynamic assessment
    • tendinopathies
  • Advantage: real-time visualization (movement).
• MRI
  • Gold standard for:
    • deep injury
    • bone edema
    • complex instability
    • ligament involvement
  • Best soft-tissue contrast.
• CT
  • 3D mapping for:
    • complex surgical planning
    • intra-articular fractures
    • arthrofibrosis/stiffness evaluation.

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Key radiographic signs (high-yield rules)

Fat pad / occult fracture logic

• Anterior fat pad
  • Often a normal variant (thin, barely visible).
  • If it becomes triangular/high → sail sign / ship’s sail → suggests pathological effusion (blood/synovial fluid).
• Posterior fat pad
  • Under normal conditions, should never be seen on lateral radiographs.
  • If present—even without a visible fracture line:
    • assume an occult fracture
    • immobilize and reassess
• Explicit caution:
  • Do not rule out fracture based solely on an initially negative X-ray if a posterior fat pad is present.

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Pediatric elbow trauma: “Critoe” and fracture identification logic

“Critoe” ossification chronology (as stated)

• Capitellum ~1 year
• Radius ~3 years
• Medial epicondyle ~5 years
• Trochlea ~7 years
• Olecranon ~9 years
• Lateral (external) epicondyle ~11 years

Vital rule (to avoid diagnostic errors)

• Medial epicondyle appears before the trochlea.
• If the trochlear nucleus is visible but the medial epicondyle is not where expected:
  • don’t assume it hasn’t appeared yet
  • search inside the joint
  • consider medial epicondyle avulsion fracture trapped within the humeroulnar joint space
  • may require surgical resolution.

Safety tip

• Always compare with the healthy contralateral elbow to identify:
  • normal variants
  • accessory nuclei
  • pseudoepiphysis-like appearances.

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Instructional content / step-by-step diagnostic workflow (“logic sequence”)

Diagnostic algorithm taught in the video

1. Step 1: Is there trauma?
   • If acute trauma or suspected fracture: X-rays first
   • If X-ray is negative but pain persists: don’t close the case.
2. Step 2: Look for the posterior fat pad
   • If posterior fat pad is visible:
     • treat as occult fracture
     • immobilize and reassess
     • posterior fat pad overrides “superficial” interpretation.
3. Step 3: Mechanical pain without acute trauma
   • Use dynamic ultrasound for tendinopathies and soft tissue pathology.
   • Pay attention to neovascularization (Doppler).
4. Step 4: Persistent deep doubt / suspicion of blockage, instability, or bone edema
   • Escalate to:
     • MRI or CT
   • Choose based on the specific clinical question (deep tissue/edema vs mechanical/bony detail).

Why follow the sequence

• Improves diagnostic accuracy
• Avoids unnecessary radiation
• Optimizes healthcare resource use

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Injury-specific concepts highlighted

Proximal radius fractures (Mason classification logic)

• Type 1: non-displaced or minimal (<2 mm)
  • treatment: functional
  • early mobilization to avoid stiffness
• Type 2: displacement >2 mm or significant angulation
  • evaluate for potential mechanical blockage → may require surgery
• Type 3: comminuted complex fragments
  • typically surgical (e.g., osteosynthesis)

Critical warning

• With any radial head fracture, always examine the wrist.
• If distal pain → consider injury to the interosseous membrane with proximal radius migration (described as interosseous membrane disruption / “exopresti” in the transcript).
• Prognosis changes because forearm longitudinal stability is compromised, not only the elbow.

“Terrible triad” (elbow)

• Three simultaneous injuries:
  1. posterior dislocation of the elbow
  2. radial head fracture
  3. coronoid process fracture
• Biomechanical emphasis:
  • coronoid is a major anterior bony landmark; its fracture (especially anteromedial facet compromise) undermines varus/extension stability.
• Mechanism described:
  • axial pressure + “embolism stress” (as transcribed) + forced supination
  • often from fall on outstretched hand with elbow semiflexed.
• Ligament actor:
  • LUCL involvement drives posterolateral rotational instability.
• Management principle:
  • comprehensive assessment of three pillars:
    • bony
    • capsular
    • ligamentous

Tendinopathy pain vs biology (ultrasound Doppler)

• Ultrasound tendon findings (common extensor/lateral epicondylalgia):
  • hypoechogenicity (structural change)
  • thickening
  • Doppler signal (neovascularization)
• Key clarification (explicitly stated):
  • Doppler signal = biological activity/neovascularization
  • not a direct correlate of pain
  • therefore:
    • Doppler may be positive with little/no acute pain
    • or acute pain may exist without a Doppler signal
• Therapeutic implication:
  • neovascular activity suggests active tissue repair
  • use controlled, progressive loading (not absolute rest)
  • aligned with evidence-based approach referenced in the transcript (“vicencino” context mentioned later).

Medial elbow pain: differentiate tendon vs UCL instability

• Need to distinguish:
  • pain from common flexor tendon
  • vs UCL instability
• Tools:
  • dynamic ultrasound with stress
    • assesses real-time joint opening and ligament integrity
  • MRI “T sign”
    • fluid leaking under the MCL/UCL region (transcribed as medial collacqueral ligament)
    • more common in overhead athletes
    • suggests chronic/partial injuries rather than complete acute rupture
• Clinical role:
  • decide whether to use progressive loading (tendon) vs conservative management or possible referral/surgical consideration (ligament instability).

Ulnar nerve evaluation requires motion

• Static imaging is insufficient.
• Dynamic ultrasound observation:
  • patient actively flexes elbow
  • check for nerve subluxation/dislocation over the medial epicondyle (“snapping phenomenon”)
• Measure:
  • nerve cross-sectional area (CSA)

  • 10 mm² suggests entrapment (context/level matters)

• Advantage claimed:
  • ultrasound shows the mechanical cause in real time, unlike clinic/static MRI.

Bone edema and sports decision-making (MRI)

• “Bone edema is a pre-fracture.”
• Edema/swelling indicates the stage before stress fracture (no cortical break yet).
• Action:
  • early unloading and training load modification
  • prevent progression to complete fracture (longer recovery).

CT for elbow stiffness: avoid forcing movement blindly

• Clinical question in stiff elbow:
  • is limitation due to soft tissue/capsule/ligament/muscle retraction?
  • or due to a bony block (bridge/osteophyte)?
• CT clarifies mechanism and guides treatment:
  • if bony bridge/osteophyte blocks motion:
    • do not force passive movement
    • forcing increases inflammation/pain
  • soft tissue origin → conservative
  • bony origin → surgical (as described).

Occlusive myositis / ectopic bone formation risk management

• Occurs after trauma with significant hematomas.
• Manage by biological phases:
  • Inflammatory/immature phase (MRI sensitive)
    • prohibited behaviors:
      • aggressive stretching
      • deep massage
      • forcing mobility
    • reason: may worsen ectopic bone formation by reactivating inflammation.
  • Mature phase (CT better defines formed bone)
    • only then is more progressive intervention appropriate.
• Core principle:
  • aggressive treatment during the inflammatory phase can worsen ectopic bone formation
  • early intervention must be gentle and progressive
  • “therapeutic patience” is a biological necessity.

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Case-based application (two cases described)

Case A (pediatric)

• Child falls; X-ray read as normal.
• Posterior fat pad is identified.
• Correct course:
  • immobilize as if a hidden fracture is present
  • do not rule out injury based solely on the initial negative X-ray.

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“Clinical pearls” (explicit checklist-style takeaways)

• Clinic rules; image confirms.
• Never neglect:
  • physical evaluation
  • medical history
• Ultrasound is the kinesiologist’s stethoscope
  • because it assesses movement dynamically.
• Pediatrics:
  • Critoe
  • bilateral comparison is mandatory
• Never confuse normal growth nuclei with fractures.
• Imaging guides the “load” (therapy), not rest alone.
• Doppler = tissue repair activity, not an automatic mandate for absolute immobilization.
• Posterior fracture sign is treated as a fracture until proven otherwise.
• Always immobilize and reassess.

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Sources / speakers mentioned in the subtitles (as credited)

Speaker (main presenter)

• Nicolás Domínguez (driving force/editorial lead behind the material)

Additional credited contributors

• Jimena Rotflug (assistant/advised editorial process)
• Julieta Colusi (assistant/advised editorial process)
• Florencia Marsden (process tutor)

Referenced authorities / works (literature and authors credited)

• American College of Radiology (ACR) appropriateness criteria (acute elbow/forearm pain context)
• Odriscol / O’Driscoll classification of coronoid fractures (and related approach to the “terrible triad”)
• Martinoli (elbow ultrasound reference)
• Sugui and “Sugbi” (as transcribed; elbow ultrasound reference context)
• Radiopaedia (collaborative educational resources)