If he has feelings of the joint being loose - it could be a ligament or tendon that has weakened. Ligaments and tendons are elastic so they can feel a bit like a "rubber band"
Rt thumb fusion '13. R&L thumb arthroplasty '12 ; RT TKR & Bilat CTS' 11. Fusions: L5-S1('87), L4-S1('93), C5-C7('06), L3-S1('10), C4-C5('13). C5-C7 foraminotomy '08