Specialty Exam Results

Radiographs

There is no evidence of fractures or degenerative joint disease on the 
radiographs.  DJD 
would be indicated if we could observe osteophytes at the patella, proximal 
tibia/fibula, 
and/or distal femoral condyle, increased or decreased opacity of subchondral 
bone, or 
articular soft-tissue mineralization.  However, since the initial stages of 
degenerative joint 
disease are asymptomatic and escape radiographic detection, and given that this 
is a 
recent injury, it is possible that either degenerative changes are present but 
are not 
evident on the radiographs at this time, or that it is too early for these 
changes to have 
taken place.    

The possibility of a cranial cruciate ligament rupture cannot be ruled out based 
on the 
radiographic evidence.  On the AP view, there appears to be compression of the 
joint 
space on the medial side, and increased joint space on the lateral side.  This 
could be due 
either to positioning or cranial cruciate ligament tear.  

A distended joint capsule, along with silhouette of the infrapatellar fat pad, 
is present, 
providing evidence for joint effusion. 

Clinical Pathology

1) Bloodwork:  

Slight leukocytosis (possibly neutrophilia, but value not provided), which 
indicates an 
inflammatory process.  There is also a slight hypoalbuminemia, accompanied by a 
hypocalcemia, which occurs with either hemorrhage or a high protein effusion, 
such as 
could occur with trauma.  The hypocalcemia is a result of the binding of calcium 
to 
albumin, and therefore does not reflect a clinically significant hypocalcemia 
(adjusted Ca++ = 9.6 mg/dl + (3.5-2.4 g/dl)= 10.7, which is within the normal 
reference interval).  

2) Synovial Joint Tap:   

The fluid is reddish and clear, indicating hemorrhage or the presence of 
erythrocytes.  
There is a good mucin clot, indicating that the joint effusion is mild and 
probably does 
not involve degradation or excessive dilution of hyaluronic acid.    The cell 
count is 
approximately 3500 cells/hpf, and consists primarily of neutrophils and 
monocytes.  This 
is typical of effusion caused by trauma.

There is no bacteria present, so the effusion is nonseptic.  

If good arthrocentesis technique is used, the presence of erthyrocytes is 
indicative of joint 
trauma and rupture of synovial capillaries.   This is due to the fact that both 
cruciates are 
covered by a fold of highly vascular synovial membrane.  Cranially, the synovial 
membrane is continuous with the infrapatellar fat pad.  Paraligamentous vessels 
branching from the main vessels in the synovial membrane penetrate transversely 
into the 
ligamentous tissues and anastomose with longitudinally arranged endoligamentous 
vessels.  This interconnecting system of vessels provides an abundant blood 
supply to all 
areas of the ligament except in the central core.  

All of the above analyses point to trauma as the cause of the joint effusion.