Fleisher was to perform Beethoven's Fifth Piano Concerto. French-Canadian pianist Marc-Andr_ Hamelin will take his place in the same work. The substitution marks Hamelin's debut with the BSO.
Fleisher's expected return to the stage will be in Florida on August 2, which coincides with the airing on HBO/Cinemax of Two Hands: The Leon Fleisher Story, an Academy Award-nominated short documentary.
Tenosynovitis, which causes tendons in the fingers to lock or stick, is a tendon and muscle disorder that affects athletes and musicians.
Fleisher suffered famously from another such disorder, focal dystonia, which struck the pianist in his late thirties, disabling his right hand. Following treatment, he returned to standard piano works in 1982, performing them intermittently thereafter but concentrating on the left-hand repertoire.
From 2004, periodic Botox injections have enabled him to resumed a regular performing career.
Fleisher, who turns 79 on July 23, was Tanglewood's music director from 1984 to 1997.