Specialty Exams

The cranial drawer sign was still negative and there was no evidence of 
arthritis or any 
other abnormalities such as increased soft tissue density on the radiographs.    
The patella 
still luxates only on the right hind leg.  With no pain response in the left leg 
or on the 
dorsiflexion of the tail, it is likely that the right limb is the only limb 
affected.  The only 
abnormality found in the right hind limb was the luxating patella.  These 
findings lead us 
away from cruciate or other ligamentous damage.  Based on the evidence we've 
reached 
the conclusion that the lameness must be from the medially luxating patella of 
the right 
stifle joint.  

One of the hypotheses had been possible cranial cruciate ligament rupture.  With 
this 
injury there should have been a positive cranial drawer sign under anesthesia.  
There also 
could have been some signs of osteoarthritis with the CCL injury.  In this case 
there was 
neither, so we ruled this hypothesis out.

Patellar luxation is one of the most common stifle joint abnormalities.  A 
medially 
luxating patella is very common in small breeds such as Pomeranians.  This is 
probably a 
grade 2/4 patellar luxation based on the intermittent non-wt bearing lameness.