Why was Blofeld in a wheelchair in the beginning of For Your Eyes Only?

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",[12] voiced by Robert Rietti.[13] 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,[12] 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