I read an article yesterday that said it was only due to his big toe. I found one then on ESPN:
http://linky.com.au/trref
Its really wierd:
"After examining Chandler's left big toe, Dr. Carlan Yates, Oklahoma City's team physician, determined that the risk of reinjury was too great to give Chandler a clean bill of health. He therefore advised the Thunder to rescind Tuesday's trade that landed them Chandler for Joe Smith, Chris Wilcox and the rights to DeVon Hardin.
"This is absolutely crazy," Chandler said in a telephone conversation Wednesday night. "I'm super shocked. This is nuts."
Chandler, 26, was baffled by Yates' ruling in part because Yates performed surgery on Chandler's big left toe in April of 2007 when the Hornets were playing in Oklahoma City. Chandler played 79 games the following season and while he's missed 19 games this season, none has been because of his toe."