Clinical history An 11 yr old female doberman pinscher had acute left pelvic limb lameness with palpation suggesting a stifle joint effusion. Joint instability was not detected clinically. Radiographs were made of both stifle joints. Left stifle - affected limb img Right stifle - clinically normal limb Radiographic changes Left stifle. Periosteal new bone
- around the trochlea of the femur
- on the proximal and distal patella
- around the intracondylar notch
- on the medial and lateral epicondyles
- on the medial and lateral aspect of the tibial plateau
Increase in density of the subchondral bone in the proximal tibia Increase in joint fluid (decrease in the size of the retropatellar fat pad) Right stifle the patella has minimal enthesophyte formation distally - there isa problem in using a singular change in a joint in an older dog as beinga part of clinically significant arthrosis rather than representing only enthesophyte formation hat is an aging change - in addition there is minimal joint effusion - that probably has clinical importance in this patient, the clinical evaluation of the right stifle was considered normal - this may influence your decision of what importance to assign to the minimal radiographic changes - Radiographic diagnosis This is a classic example of early bony changes in the left stifle joint secondary to joint instability probably following injury to the cranial cruciate ligament - no signs of major joint instability are evident - joint effusion is prominent. The right stifle joint is radiographically normal. The older age of the patient and unilateral involvement of the arthrosis is somewhat unusual. Comments Arthrosis in the stifle joint of a large breed dog is usually assumed to be the result of cruciate ligament injury - this may be a partial tear but creates a joint with minimal joint instability with secondary bony changes - with complete rupture of the cruciate ligament the instability is more evident and the bony changes become much more prominent with time. The location of the new bone reaction secondary to joint instability is always predictable - thus, even if the bony changes are minimal they can be assigned clinical importance and the suspect diagnosis of joint instability can be made.
