Presentation
Left thumb trauma about 4 weeks ago. Complaining of thumb base pain and swelling on the ulnar aspect.
Patient Data
Mild widening of ulnar side joint space of thumb metacarpophalangeal joint along with the presence of a tiny bone flake on the ulnar side of thumb metacarpal head.
Ulnar collateral ligament of metacarpophalangeal joint
Not present at the normal location
There is a hypoechoic pseudomass formation just proximal to the metacarpophalangeal joint; abutting metacarpal head.
A bone flake ( about 3 mm ) is present in this pseudomass.
Metacarpophalangeal joint
The wide opening of the ulnar side joint space with abduction stress.
Mild effusion
Proximal phalanx base
Cortical irregularity due to avulsion
Radial collateral ligament of metacarpophalangeal joint
Intact with normal echopattern
Flexor tendon
Normal echopattern.No tenosynovitis.
Extensor tendon
Normal echopattern
Interphalangeal joint
No effusion
Collateral ligaments are intact.
Abduction stress applied to check metacarpophalangeal joint. There is radial side subluxation at thumb metacarpophalangeal joint.
Case Discussion
A female presented with left thumb base pain, swelling with a recent history of thumb trauma. Radiographs show an avulsed bone flake on the medial aspect of thumb metacarpus head with a mild widening of ulnar side metacarpophalangeal joint space. Ultrasound shows a pseudomass formation abutting the ulnar side of metacarpus with the absence of normal ulnar collateral ligament at its location. There is also an avulsion from proximal phalanx base. Findings favour Stener lesion which requires surgical treatment.
Abduction stress view radiograph was done after ultrasound confirmation of pathology. This view is not recommended because it can cause a Stener lesion in ulnar collateral ligament tear/avulsion.
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