CMO affects terriers, primarily, although it's been reported in other breeds. I'll have to check my copy of Padgett's when I get home to see whether there are reports of this disorder affecting bassets.
CMO is an inherited disorder, requires x-rays for definitive diagnosis, and can be quite painful. It's managed with pain medication, if necessary. Fortunately, puppies tend to "outgrow" it, to the point that it may be unnoticeable in adult dogs.
Affected dogs should not be used for breeding. You might consider informing your puppy's breeder of his diagnosis; a responsible breeder would certainly want to know about this.