Ulnar Collateral Ligament Ultrasound of the First MCP with High Resolution Probes on Cadavers and Healthy Subjects

WANG David1, Brion BENNINGER1-9. Medical Anatomy Center1, Departments of Medical Anatomical Sciences2, Neuromuscular Medicine3, Family Practice4, Western University of Health Sciences, COMP–Northwest, Lebanon, OR. USA.... [ view full abstract ]

WANG David1, Brion BENNINGER1-9. Medical Anatomy Center1, Departments of Medical Anatomical Sciences2, Neuromuscular Medicine3, Family Practice4, Western University of Health Sciences, COMP–Northwest, Lebanon, OR. USA. Departments of Orthopaedics5, General Surgery6 and Sports Medicine7,Samaritan Health Services, Corvallis, OR. USA. Departments of Surgery8, Orthopaedics & Rehabilitation9, Oregon Health & Science University, Portland, OR. USA.

INTRODUCTION. The ulnar collateral ligament (UCL) of the first metacarpophalangeal (MCP) joint is commonly injured from a fall causing hyperextension and abduction of the thumb. Diagnosis is made following physical examination and X-ray to rule out avulsion fracture and/or Stener lesion. This study investigated if medical students (MS) could use ultrasound (US) to identify UCL from cadavers and healthy subjects. METHODS. Literature search was conducted regarding US of UCL by MS. Recently deceased unembalmed donor cadavers (RDUDC) received 324 (108 per probe) trials from MS using 3 different US probes(5-12, 18, 22 MHz) and 42 trials on healthy individuals. All MS conducted timed trials bilaterally. RESULTS. There is an estimated 200,000 cases annually of ulnar collateral ligament tear at the 1st MCP joint. 216/216 trials successfully identified UCL with 18 & 22 MHz probes, (108 trials failed to clearly identify UCL with 5-12 MHz probe). 42 trials with 18 MHz probe on a healthy individual revealed 57% accuracy on the left side and 74% accuracy on the right. DISCUSSION. Literature search revealed no known studies regarding medical students identifying UCL with ultrasound. This study demonstrated MS with novice ultrasound skills could identify the UCL using high-resolution probes. UCL injury of the first MCP joint is confirmed by physical diagnosis and X-ray to exclude fractures. However, ultrasound is now becoming the standard to identify UCL tears with or without Stener lesions. Ultrasound allows for dynamic examination during passive movements to review injuries to the UCL distal attachment at the base of the proximal phalanx of the thumb. The 18 MHz probe allowed those students to identify the UCL from RDUDC and healthy volunteers while the 5-12 MHz probe made viewing the UCL very difficult. CONCLUSION. This study revealed medical students could successfully scan the UCL on cadaveric specimens and healthy volunteers with high resolution probes.