Well, it's not dysplasia...

[afrikaPB]

Nugget's been showing signs of dysplasia or some other structural issue. While standing, his back legs will sometimes suddenly "roll" out at the hock (making him look bow legged), and when he walks at a relaxed pace, his hind legs roll as if he were knock-knee'd (but at the hocks). So, I got him x-rayed, and it turns out... The doc thinks his hips look great! We also did rads of his lower spine, and those look fine too. He was palpated and rotated and pulled and pushed and he has great mobility and everything seems to fit just right. Second opinions on the x-rays are welcome (a specialist will also be looking at them later this week).
The doc suspects it might be a neurological problem, but is loathe to recommend MRI/further testing unless symptoms worsen since it's intensive and pricey and even then difficult to diagnose accurately. Does anyone have a dog with similar 'difficult to explain' symptoms or a dog with a similar neurological disorder? I am on unfamiliar territory here...
Nugget isn't "bonks his head for no reason" clumsy, but he isn't always the most coordinated dog-however I always chalked it up to him being a young pittie. He also nurses his toys and has facial twitches when he does it, though the doc isn't sure this is related. He had seizure activity when sedated for neuter, but it was assumed to be a drug reaction.
Hmmm...

[Misskiwi67]

I would do some reading on "wobblers" and see if that sounds similar to you.

I agree, those are some nice, normal, radiographs.

[Leslie H]

http://www.optigen.com/opt9_cerebellarataxia_amstaff.html

There is a neurological disease, ataxia, found in Amstaffs, and in APBT's w/staff blood. There's a DNA test for it. I hope this isn't what your dog has.

[afrikaPB]

I looked into Ataxia the moment I got home, but the symptoms don't seem to match up. I think a blood test may be in order regardless. Also doesn't seem to match up exactly with what wobblers looks like... But am wishing we had done a myelogram while he was under. Will speak to the vet re both possibilities.