the 12 tendons of the fingers run across the elbow joint.
One word: "Extension"
When you rehab, get a set of various sizes and thickness rubberbands and wrap them around your fingers. Do "extension" type exercises. Go for the burn.
We spend a lifetime squeezing and gripping. Same thing that causes "shin splints" -- a muscular 'imbalance'
One side of muscles on the bone is stronger than the other. Same for side to side ratios. Baseball players who hit predominantly on one side are much weaker on the other. Sooner or later, the other 'weak' side takes a dump.