Complex sentence: It has been reported to be the most important restraining structure of the first CMC joint by several researchers, while some consider it too weak to be able to stabilize the joint by itself, but that it together with the UCL represent an important restraining structure.
Split into simpler sentences: It has been reported to be the most important restraining structure of the first CMC joint by several researchers. In contrast, some consider it too weak to be able to stabilize the joint by itself, yet accept that together with the UCL it represents an important restraining structure.