In the pre title sequence of For Your Eyes Only Blofeld is in a wheelchair. Why?
First of all, this is technically speaking an unnamed villain, NOT Blofeld (despite resembling him). To quote Wikipedia:
John Hollis as the "bald villain in wheelchair", voiced by Robert Rietti. The character appears in the pre-credits sequence and is both unnamed and uncredited. The character contains a number of characteristics of Ernst Stavro Blofeld, but could not be identified as such because of the legal reasons surrounding the Thunderball controversy with Kevin McClory claiming sole rights to the Blofeld character, a claim disputed by Eon
The reason the character is in the wheelchair is that in the last Bond movie where he was a character (Diamonds are Forever) Bond crashed a mini-sub that Blofeld was using to escape into a control center, blowing up the platform and presumably injuring Blofeld.
You would have thought he was in the wheelchair because of what happend in O.H.M.S.S . here is the scene Bobsled chase neck injury blofelds neck gets caught in a branch severley injuring him . but he seems fine in diamonds are forever untill the end described in the answer above