Elbow pathology

Common Extensor Tendon Pathology

The Common extensor tendon on the lateral humeral epicondyle, is the common origin of the:

  • Extensor digitorum (ED)
  • Extensor carpi radialis brevis (ECRB)
  • Extensor digiti minimi (EDM)
  • Extensor carpi ulnaris (ECU)

The majority of pathology appears to occur in the ECRB portion of the common tendon.

Underlying this tendon are the Radial collateral ligament (RCL) and an oblique portion of the Lateral Collateral Ulna Ligament (LUCL)

Ultrasound image shows prominent convexity of the tendon surface and alteration of the fibrillar architecture consistant with tendinosis.

Ultrasound image- Hypoechoic tendinosis. See the increased vascularity in the next image confirming acute rather than chronic.

Ultrasound of the common extensor tendon origin at the lateral epicondyle of the elbow. There is increased vascularity consistant with active inflammation. Also a concavity (dip) in the tendon contour suggesting a partial thickness tear.

However the 2nd image shows the same tendon afew mm to the side. This demonstrates the importance of scanning thoroughly.

The normal tendon should have no visible internal vascularity.

Ultrasound image- A chronic partial tear of the CET involving the Extensor carpi radialis brevis (ECRB) portion.

Ultrasound image- Increased vascularity consistent with an acute process within the Common Extensor Tendon insertion.

Distal Biceps Tendon

  • With careful interrogation, the two separate footprints of long and short head can be seen inserting onto the radius.
  • The long head has a longer tapered insertion & acts as a pronator.
  • The Short head has a smaller footprint being the elbow flexor.

Ultrasound image- A large effusion surrounding the distal Biceps tendon.

Ultrasound image- Calcification in the distal biceps insertion (long head).

Ultrasound image- Biceps tendon calcification.

Ultrasound image- Intrasubstance tear of the distal biceps tendon.

Transverse ultrasound image- Intrasubstance tear of the dista biceps tendon.

Ultrasound image- A post traumatic effusion around the distal tendon insertion.

Olecranon Pathology

Olecranon Bursitis

  • A common presentation is an ‘egg-like’ swelling over the olecranon tip of the elbow.
  • May be tender or assymptomatic.
  • Can become infected or inflamed.
  • Differential diagnoses are gout (& pseudogout), synovial cyst from the joint or haematoma from injury.

A panoramic ultrasound view of the typical hypoechoic heterogeneity seen with a distended/thickened olecranon bursa.

Ultrasound image- The marked internal vascularity is readily apparant confirming bursal tissue rather than merely complex fluid.

Olecranon Fossa

  • ‘Loose bodies’ (either calcifications or fracture fragments)
  • Effusions.

Ultrasound image- Post traumatic fluid in the olecranon fossa. During extension, this ‘pushed’ over the medial humerus causing ulnar nerve distribution pain.

Ultrasound image- A calcific loose body in the Olecranon fossa. This causes restricted range of movement, particularly extension. Also called a ‘loose body’.

Ultrasound image- This image shows both Olecranon bursal fluid (red) and fluid in the olecranon fossa (blue) deep to the distal triceps.

Ulna Nerve Pathology

  • Neuromas and subluxing ulna nerve are common pathologies.
  • Up to 20% of the population may have subluxing ulna nerves.

(REF: Recurrent ulnar nerve dislocations at the elbow. HM Childress. CORR. Vol 108, 1975. p 168-170.)

Assess by scanning in transverse over the ulna groove and ask the patient to flex the elbow until their hand is at their shoulder. The nerve will flip over the epicondyle at the extreme of flexion.

Ulna nerve neuropathy

Ultrasound image- Neuritis of the Ulnar nerve secondary to a small fracture of the medial humeral epicondyle (blue arrow).

Ultrasound image- The ulnar nerve (yellow) surrounded by an inflammatory halo (green).

Ultrasound image- Longitudinal view of fusiform thickening of the ulna nerve at the ulna groove.

Transverse ultrasound view of the Ulna nerve at the level of the ulnar groove and then distal to the groove showing the difference in diameter.

Ulna nerve subluxation / dislocation

Ultrasound image- During extension, the ulna nerve dislocates out of the groove to lie on the CFT. Then relocates during elbow extension and dislocating again with return to flexion.

Ultrasound image- A still image shows the ulnar nerve dislocated, sitting on the Common Flexor Tendon.

Radial Nerve Pathology(Posterior Interosseous Nerve- PIN)

  • The deep branch of the radial nerve is called the Posterior Interosseous Nerve.
  • The Arcade of Frohse is common place for entrapment. This is where the nerve passes though the supinator.
  • Whilst scanning, ask the patient to clench/unclench their fist or pronate then supinate with resistance. (see video below)

Ultrasound image- Posterior interosseous nerve at the arcade of Frohse.

Imaging the posterior interosseous nerve (PIN) longitudinally as it passes through the arcade of Frohse.

Assessing the nerve during resisted supination shows entrapment of the nerve between the muscle bellies.

A great informative site for anatomy and orthopaedic pathology is the “Wheeless’ Textbook of Orthopaedics”

Elbow joint osteo arthritis (OA)

Look for:

  • Bony irregularities
  • Joint effusions
  • Synovial thickening
  • Carilage loss or calcification

Xray showing elbow osteo arthritis. AP & lateral projections.

Osteophytic lipping and exostoses.

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