To assess for:
- muscular, tendinous and ligamentous damage (chronic and acute).
- Foreign bodies.
- Joint effusions.
LIPOMA.
- Soft tissue masses such as ganglia, lipomas.
- Classification of a mass eg solid, cystic, mixed.
- Post surgical complications eg abscess, edema.
- Guidance of injection, aspiration or biopsy.
- Relationship of normal anatomy and pathology to each other.
- Some bony pathology.
hypermia close to dip joint.
Finger Flexors
There are 2 flexor tendons of the fingers:
- Flexor digitorum superficialis, inserting as 2 separate slips onto the base of the middle phalanx.
- Flexor digitorum profundus, inserting onto the distal phalanx.
Pulleys
The flexor tendons are secured in place by a series of pulleys which are fibrous bands wrapping over the tendons and attaching to the bone.
- Annular pulleys: which wrap transversely over the tendons.
- Cruciate pulleys: which are paired and cross diagonally over the tendons.
The annular pulleys are readily visible with high resolution, high quality equipment. The cruciate pulleys are poorly seen.
DORSAL ASPECT
Extensor digitorum tendons
Unlike the flexors, there is only an extensor digitorum
Ulnar collateral ligament of the thumb (UCL) last 2 pictures
- The ulnar collateral ligament of the 1st metacarpo-phalangeal joint medially.
- Rupture is a skiier’s or gamekeeper’s thumb. If the torn ligament folds under the adductor pollicis it is referred to as a ‘Stenner lesion’.
Use of a high resolution probe (7-18 MHZ) with a small footprint is essential when assessing superficial structures. Careful scanning technique to avoid anisotropy (and possible misdiagnosis). Beam steering or compounding can help to overcome anisotropy in linear structures such as tendons. Good colour / power / Doppler capabilities when assessing vessels or vascularity of a structure. Be prepared to change frequency output of probe (or probes) to adequately assess both superficial and deeper structures.
SCANNING TECHNIQUE
- Sit the patient on the side of the bed with a pillow on their lap to support their hand, or
- Sit the patient on a chair on the opposite side of the bed with their hand resting on the bed.
Look for Joint Effusions, tend sheath cyst and thickness, hypermia . When you find an effusion check for the
- Size
- Simple/complex
- Any synovial thickening
- Any vascularity on power Doppler – Normal is little or no discernable flow. Hyperaemia = acute.
May need to compare with the other side.
Tendon abnormalities
Look for hyperemia, tendon sheath fluid (simple/complex) and tendon integrity/homogeneity
- Check for tendon thickening (compare with other side)
- Fluid in the tendon sheath
- Integrity of the tendon- any tear?
- does the tendon slide freely when mobilised?
Dupuytren’s contracture ; What is it?
- Fibrosis of the palmer fascia forcing the flexion of the 4th/5th fingers.
- Gradual onset
- MALE >FEMALE
- Often inherited.
- Generally affects 4th and 5th fingers.
Scan in longitudinal from the base of the proximal phalanx down into the palm looking superficial to the flexor tendon. It will appear as a hypoechoic focal fusiform thickening of the palmar fascia at the metacarpal head level. Not to be confused with trigger finger .
Trigger finger; What is it?
Tenosynovitis of a flexor digitorum tendon causing forced flexion of a finger.
Initially in transverse, identify the flexor digitorum tendons at the metacarpal head level. Follow the common tendon proximally to the carpal tunnel. Then follow distally to the insertions: The Flexor digitorum superficialis divides, with two slips inserting onto the side of the base of the middle phalanx. Flexor digitorum profundus inserts onto the distal phalanx.
Finger Pulleys; What are they? Bands of fibrous tissue holding the flexor tendon to the finger similar to runners on a fishing rod.
They are named according to their type-Annular (around) or Cruciform (cross), and numbered from proximal to distal. A 1 TO 5.
Scan longitudinally over the anterior surface of the finger. The pulleys may be seen as thin hypoechoic zones intimately overlying the flexor tendon sheath.
If ruptured, the tendon will no longer follow the bone and will instead “bowstring”.
Game keepers thumb/ skiiers thumb ; Rupture of the ulnar collateral ligament of the thumb due to a sudden valgus force. May occur after repeated stretching of the ligament. The ligament usually tears at it’s distal end from the base of the proximal phalanx. If there is marked angulation of the phalanx, the flailing ligament may impinge under the adductor pollicis creating a ‘ Stenner lesion ‘.
Neuroma
Foreign bodies ; Ensure you approach the proposed site of the foreign body from different angles. Some materials will be poorly reflective and almost invisible unless the beam is perpendicular to them. There will usually be a surrounding hypoechoic halo representing an inflammatory reaction
Identify:
- The plane of tissue it is in.
- How close it is to the entry wound and to any blood vessels.
- It may be helpful to mark the location and orientation of the foreign body on the skin to guide removal.
- Masses
95% of finger tumors are benign.
- abscess
- granuloma
- Ganglia
- Neuroma
- Fibroma
- Glomus tumour (nail bed tumour)
Joint Abnormalities
- Gout: Abnormal uric acid metabolism resulting in joint inflammation. May see tophaceous gout as a complex echogenic mass (tophus) in the soft
- Osteoarthritis: Bony irregularity at the bone ends with joint effusion. When acute the joint will be hyperaemic
- Rheumatoid arthritis: Thickened synovium with a complex ‘thick’ joint effusion, pannus & associated bony irregularity.
Thank you for reading.
Steve Ramsey, PhD.
Calgary, Alberta- Canada.