Management : Partial Meniscectomy, Notchoplasty and Intracapsular under and over technique

	Conservative management is not an option for this dog.  This is a large breed, obese dog that will not recover with rest only and will progress into irreversible degenerative changes.  Surgical intervention is required to examine possible meniscal injury, because the continued back and forth sliding of the tibia and femur will lead to degenerative joint disease.  The possibility of a partial tear in the right hind leg at the present time also discourages conservative management as that will increase the chance of rupture in that leg.  Surgical intervention is the treatment of choice.  There are a myriad of different ways to surgically correct this rupture and the success rate with anyone of them is near 90%, so the choice of procedure is based on the surgeons experience and comfort level.
Before surgery begins we must consider pre-operative management.  Activity should be limited before surgery to prevent further damage to articular cartilage caused by the instability.  According to the blood work, the animal appears healthy and there is no major organ dysfunction, so Bonnie is not a risk for surgery.  Clinical and experimental studies indicate that analgesics are most effective when administered before a painful stimulus.   Because Bonnie is already in pain and because this surgery will most likely cause post-operative pain, an opiod epidural will be administered right after induction.  
	This dog will receive Glycopyrelate, Oxymorphone and acepromazine as a premed and then be induced with Thiopentanol.  We will maintain her on iosflourane throughout the surgery.  We will not use antibiotics prophalactically because this joint is not open or contaminated, no bacteria were seen in the joint tap.  There are also no fractures present and hopefully the surgery will take less than two hours (unless an intern decides to close).  Bonnie is then placed in lateral recumbency and the left hind leg is shaved from hock to midline all the way around the leg.  The leg distal to the hock is then wrapped in tape and the leg is hung.  Cleaning the leg then begins with chlorexidine and alcohol scrubs and the dog is then rolled into the OR.  She is draped in and a lateral approach is made to the stifle.  An incision is made all the way through to the joint capsule.  The patella is displaced medially to expose the cranial surface of the joint.  The medial meniscus is examined and, if injured, a partial meniscectomy is performed.  The meniscus is protective of the joint cartilage, removal of all of the medial meniscus would cause an inflammatory state within the joint cavity and increased degenerative changes in the adjacent bone and cartilage.  The effect is proportional to the amount of meniscus removed, so as little as possible should be taken.  Pain is associated with the free meniscus moving around, so only the pieces that are damaged and freely moving are excised to prevent lameness and pain.  Fixing the cranial cruciate rupture will also decrease tibial rotation and will prevent the meniscus from getting trapped between the tibia and femur.
	A notchoplasty is then performed to remove the osteophytes that have formed on the lateral femoral condyle.  Removal of this new bone and reshaping the intercondylar notch will facilitate the passage of the intra-articular graft through the notch and will prevent graft impingement during extension.  We are choosing to do an intra-capsular reconstruction using the under and over technique with an autograft.  IT is convenient to use this type of graft because we can harvest it right from the patient and there won't be an immune response like there would to an allograft.  The distal facia lata and lateral 1/3 of the patella tendon will be used.  The graft will remain attached to the tibia and then passed through a tunnel in the tibia, then through the joint, through another tunnel in the femur and finally attached to the caudo-lateral side of the femur with a screw and washer.  (The washer and screw do not have to be removed unless signs of irritation or inflammation or lameness appear later)   This will mimic the pathway of the cranial cruciate ligament.  The incision is then closed and the dog is recovered.  A soft bandage is placed around the joint to help minimize swelling, and protect the wound.  The bandage should be maintained for two weeks to reduce the stress on the graft.
	Post-operative care is crucial in the full recovery of the joint.  The oxymorphone used as pre-surgical epidural should last for 10 hours.  If at this time the patient recovers and is still in lots of pain, more can de administered intravenously.  Cold therapy is used for swelling control and analgesia during the first 2-3 days after surgery.   A cold compress is applied to the area for twenty minutes three times a day.  Then during the chronic phase of healing, maybe beginning after the first week, heat therapy is applied.  This decreases pain and improves circulation to the joint.  It also relaxes muscles before passive physical manipulation.  A moist, hot towel can be applied to the stifle joint being careful not to burn the skin!  Bonnie should begin to stand on the affected leg within the first post-operative week.  Raising the uninjured leg will force Bonnie to stand on the injured leg.  This should only be done for 1-2 minutes and then gradually increase the duration until she is weight bearing on her own.  Passive physiotherapy involves controlled stretching of the muscles, tendons and ligaments and gently flexing and extending the joint.  This is done gradually to increase the range of motion.  This exercise does not increase muscle tone or strength and therefore needs to be combined with physical therapy.  Swimming is excellent therapy for it combines both joint movement and strengthen muscles without impact loading.  However caution must be taken when entering or leaving water so as not to slip and re-injure the leg.  Leash walking should be done slowly gradually increasing the duration of the walks and level of activity.  By twelve weeks full activity can be resumed.
	Bonnies weight should be assessed.  A weight management program should be implemented to decrease the stress on the joint.  The daily energy requirement should be equal to the resting energy requirement as to limit weight gain.   A high fiber diet is useful in controlling weight.
	Because the changes seen in osteoarthritis are irreversible the primary goal of treatment is pain relief.  This is done primarily by the use of nonsteroidal antiinflammatory drugs (NSAIDs).  These drugs work by inhibiting the production of prostaglandins and cytokines.  As mentioned in hypothesis 2, prostaglandins and cyokines are responsible for the pathway that leads to degradation of the cartilage matrix.  Bonnie should be put on Rimadyl (twice a day) or Etogesic (once a day).  Both of these NSAIDs have been shown to be effective for the treatment of osteoarthritis. Corticosteroids should not be used because it results in damage to the articular cartilage with long term use. Aspirin can be substituted if cost is an issue. Chondroprotective drugs such as PSGAGs, glucosamine, or chondroitin sulfate can also be used in the management of osteoarthritis.  Another goal in treating DJD is to slow the development of further development changes. This can be accomplished with surgery and proper management.  Because the DJD seen in Bonnie is likely secondary to rupture of the cranial cruciate ligament stabilization of the stifle joint should retard degenerative changes.  Control of the diet, exercise modification (including rest), and physical therapy will also slow degenerative changes by decreasing inflammation and strengthening the supportive structures of the joint.  Treatment for cranial cruciate ligament rupture, as well as exercise and diet modification, were addressed above and thus will not be discussed any further here.