The patients who had UCL injury at the MCPJ must have the history of trauma and localized pain and swell in the ulnar aspect of the MCPJ.
Every UCL at the MCPJ of thumb, central slip, terminal tendon, and FDP of fingers was analyzed in the 16 cadaveric hands and 20 volunteers' hands.
The UCL at the MCPJ originated from the ulnar aspect of the dorsal tubercle of the first metacarpal and inserted into the base of the proximal phalanx.
At the level of MCPJ, the FDS split into two beams bypassing the FDP, while they remerged into a beam at the PIPJ and inserted on the midportion of the middle phalanx [Figure 3].
The term Gamekeeper's thumb was applied to both acute and chronic injuries of the UCL at the MCPJ of thumb. When the torn UCL retracted and lay superficial to the AA, this lesion was termed Stener lesion [Figure 7]. Among the 12 cases with the injury of the UCL, eight cases were Stener lesions and showed the discontinuity and thickening of the UCL with increased signal intensity and displacement superficially to the AA [Figure 7].
To evaluate the hand and wrist involvement of the patients, the ROM of the wrist, MCPJs, and PIPJs was measured via goniometry.
The results for the MCPJs and PIPJs were evaluated according to the total ROM, which is the sum of the flexion and extension ROM.
Additionally, the Larsen score was calculated in the radiological evaluation, and the following 15 joints were evaluated: the four quadrants, six MCPJs, and four PIPJs of each wrist along with the interphalangeal joint (IPJ) of the two thumbs.
(1), (15) Previous studies have revealed that the earliest erosions occur in the second and third MCPJs followed by the wrist joint.
(21) Boutonniere deformity occurs especially because of the involvement of the PIPJs, whereas swan neck deformity may include three joint involvements consisting of the MCPJs, PIPJs and distal interphalangeal joints (DIPJs).
A Stener's lesion (a clinically palpable area near the MCPJ caused by interposition of the adductor aponeurosis between the ends of the torn ligament) was present in 15 of 17 cases (87%).
The fracture may not represent a simple bony avulsion by itself, but a fragmentation of the ulnar volar aspect of the proximal phalanx associated with a complete disruption of the UCL as well.[17-18] The radiologic technologist should query the ordering physician if no stress radiograph is ordered and the patient complains of pain over the first MCPJ and has a compatible history.