Plan of Action


* Physical and radiographic exams generally confirm chronic degenerative changes in the affected stifle joint.
* Sedated orthopedic examination looking for stifle instability, cranial drawer in both stifles, and hip instability.
* Radiographs of both stifles including femur and tibia, looking for abnormal alignment and shape of the bones, joint effusion, degenerative joint disease and narrowing of intercondylar fossa, 
* If hip pain is found then radiograph the hips as well, looking for luxation, healed fractures of the femoral neck or developmental abnormalities in the bones surrounding the joint.
* Preoperative PCV, UA and total protein if surgery is planned.   Everything should be normal 
* Arthrocentesis and fluid analysis should be done.  We would expect synovial fluid white blood cell counts of less than 5,000/mm3, with the cells generally being mononuclear if Bonnie has CCL rupture, and elevated total white blood cell counts in synovial fluid if she has a partial tear.
* Complete Blood Count (CBC) to help determine systemic involvement. We expect normal serum chemistry and hematology findings.




Physical Exam
	Cranial Cruciate ligament rupture is usually diagnosed based on a history of lameness and physical examination findings. While observing conformation we would expect to see a bowlegged conformation, internal rotation of the tibia, or straight stifles if Bonnie has cruciate disease.  Bonnie will present with severe lameness, and will occasionally not bear weight on her left hind limb if she has acutely ruptured her cranial cruciate ligament (CCL) due to trauma.  Muscle atrophy would not be seen if this is an acute case.  Bonnie would generally resist routine manipulation of the joint, because elicitation of the cranial drawer sign often causes pain.  A truly acute onset of lameness, usually with a definite history of injury, and the presence of little to no degenerative joint disease in the left stifle is key to diagnosing traumatic rupture of the CCL in Bonnie.  
	Bonnie would present with a more gradual and subtle history of lameness, which is often intermittent and exacerbated by her strenuous exercise regimen if she has chronic cruciate disease.  Her left stifle should be thickened, especially medially, and there should be some evidence of degenerative joint disease on radiographs of the stifle region.  A cranial drawer sign may be difficult to elicit due to periarticular fibrosis, especially if the CCL is partially torn.  Upon sedation, some degree of abnormal movement should usually be detected.  Joint effusion should also be present upon physical examination if Bonnie has chronic CCL rupture with degenerative joint disease.  
	 Crepitation upon physical exmaination is suggestive of osteophyte formation or articular cartilage damage. Although slight increases in the volume of synovial fluid are present joint effusion is usually not noted with osteoarthritis.

Orthopedic Exam
	The exam will be performed with the Bonnie standing on the floor to avoid the stress of being held down on a table.  We want to palpate the general contour of the left leg, paying attention to her muscle mass and sites of pain, and comparing this with the opposite side.  A thickening of the medial joint capsule will readily be detected by palpation if Bonnie has chronic CCL rupture.  Joint effusion should also be detected by careful palpation of the joint space on either side of the patellar tendon, and compared with the opposite side to determine if Bonnie is bilaterally affected.  The edges of the patellar tendon should be sharp and distinct if Bonnie has a normal joint.  During the orthopedic exam, we will gently move the stifle joint through a range of motions, while paying attention to crepitation pain, and clunks or clicks that suggest meniscal damage.  However, the lack of a clicking sound would not suggest that the joint is normal.  
	The cranial drawer test should be done again to diagnose a partial or complete CCL rupture.  An abnormal cranial drawer motion in both the extended position and in flexion is expected if Bonnie has a complete tear of the CCL.  On the other hand, cranial tibial displacement should be prevented if Bonnie has a partial tear with the caudolateral portion of the CCL intact.  Although highly unlikely in this case, isolated rupture of the caudolateral portion of the CCL may prevent detection of drawer motion, regardless of joint position.  

Radiographic Examination
	High-quality radiographs are important in demonstrating early signs of degenerative joint disease and joint effusion, which will cause a cranial displacement of the infrapatellar fat body.  Both stifle joints will be radiographed for comparison, because degenerative joint disease in the right stifle increases the likelihood of CCL rupture compared with normal contralateral joints.  A radiograph of the intercondylar fossa may also be taken to observe for narrowing associated with the development of osteophytes within the fossa, which is commonly seen in dogs with chronic instability of the fossa due to CCL rupture.  
	Features characteristic of dogs with degenerative joint  disease include narrowing of the joint space, intra-articular or peri-articular  formation of osteophytes, and subchondral bony sclerosis.  The joint  space appears more narrow  in DJD because the subchondral bone is in closer contact  with  each other. This is due to the loss of articular cartilage which allows the more radio-dense subchondral bone to get closer thus resulting in what appears to be a more narrow joint space.  The most common radiographic finding of DJD of the stifle is the formation of peri-articular osteophytes at the attachment of the synovial membrane.  The presence of osteophytes is suggestive of abnormal activity within  or adjacent to the joint.    Subchondral bony sclerosis is usually seen in chronic DJD and is visible under the articular cartilage of the affected joint as a homogenous radio-dense  area.  This change occurs because in the normal joint stress is shared by the articular cartilage and the subchondral bone. With the destruction of the articular cartilage the stress to the subchondral bone is increased resulting in sclerosis.

Clinical Pathology
	Serum chemistry and hematology findings will be normal if Bonnie has CCL rupture.  Analysis of joint fluid should show synovial fluid white blood cell counts of less than 5,000/mm3, with the cells generally being mononuclear if Bonnie has CCL rupture.  This finding is consistent with chronic degenerative joint disease. Bonnie may have elevated total weight blood cell counts in synovial fluid if she has a partial tear. A large number of polymorphonuclear cells is suggestive of immune-mediated joint disease.     
	The results of the CBC, serum chemistries, and urinalysis would be within normal limits unless there are other existing conditions if Bonnie has osteoarthritis.  A low grade intra-articular inflammatory process is usually confirmed by the findings of an increased number of mononuclear phagocytic cells in the synovial fluid, an increase in the volume of synovial fluid, and a decrease in synovial fluid viscosity (due to the decrease in hyaluronic  acid production).
	 The most accurate diagnostic test for Borrelia burgdorferi are IFA and ELISA tests.  An ELISA and flourescent antibody test should be perforomed on the joint effusion fluid to rule out systemic disease due to Lyme Diseases.  A neutrophilic inflammation will be demonstrated if Bonnie has Lyme Disease.  Radiographically, there is evidence of joint effusion, but no evidence of degenerative joint disease.