Hi Diane,
This is a complex joint and requires some niche knowledge to best assess the volar beak ligament (between the trapezium and the metacarpal base on the solar aspect) and the dorsal radial ligament between the same bones on the radial aspect.
The transverse carpal ligament (roof of the carpal tunnel) also helps stabilise the joint.
The master of this joint is the great Greg Lammers from Melbourne,
In 2019 he presented a cracking good paper on the subject at the ASA meeting.
I can share some of Greg’s amazing work with you via email.
I also have some journal articles I can share.
Steve.