Stifle Injury - Surgical vs Non-Surgical
What is a stifle joint?
The stifle (knee) joint is located between the end of the femur and the top of the tibia. Within the stifle are two ligament bands that cross over each other attaching the femur to the tibia. These ligaments prevent the leg from overextending (hyperextension) and rotation of the lower part of the leg (internal rotation of the tibia). The front most ligament, (cranial ligament) is the most commonly torn of the two ligaments. Think of this ligament as a rope. There are many smaller strands of tissue that make up the entire structure. If you start to break apart these smaller strands eventually the integrity of the structure is weakened, and continued strain on this area will lead to complete rupture (rope slowly getting cut one strand at a time until the rope snaps completely). A partial and complete tear then causes instability in this joint, because the femur slides backwards and down off the tibia as the tibia moves too far forward. This extreme movement can damage another structure that makes up the stifle joint, the menisci.
The menisci are crescent-shaped pieces of cartilaginous tissue that make up the stifle joint between the femur and tibia. The menisci provide a cushion like support during weight bearing, lubrication and nutrition to the stifle joint and provides the stifle structural integrity. The menisci attach to the surface of the bones which can make them more prone to tearing away from these surfaces secondary to abnormal torque and uneven pressures caused by a cruciate ligament tear.
Correction either by surgical intervention or external support by use of an orthotic (brace) will need to be done. Continuous instability of the affected leg will lead to further damage within that joint, as well as more strain on the other hind leg which increases the risk substantially of the “good knee” also rupturing. Lower back dysfunction, pelvic dysfunction and muscle tension are also other secondary issues that arise due to a stifle injury. Therefore, it is crucial to provide stability as soon as possible within the affected joint to prevent further damage, to prevent causing injury to other joints, and prevent secondary issues from occurring or becoming debilitating.
Referrals can be made to Hospitals that offer surgical correction. The most common types of repairs are Extracapsular (suture repair), TPLO (Tibial plateau leveling osteotomy) or TTA (Tibial tuberosity advancement). Breed, size and activity of the animal will all be factors that will help determine which repair is most suitable.
Extracapsular Repair (suture)
This repair uses a nonabsorbable suture that is wrapped around the outside (external) of the joint in a pattern (figure 8 or loop) and passes through a small hold drilled into the front part of the tibia. This provides support and prevents the opposing movements of the femur and tibia. The goal for suture repair is to allow time for the body to organize scar tissues around this joint which will provide more stability before this suture eventually will break down and snap.
TPLO involves cutting into the tibia and changing the surface angle to a lower one to help prevent the extreme pressures, torque and movements within this joint. Once the appropriate angle is determined a metal plate is used to hold this change in bone angle in place while the bone heals. Follow up x-rays are done to monitor healing of the bone.
TTA also involves cutting into the tibia but not in the same way a TPLO does. The front part of the tibia is cut and advanced until the patellar tendon is perpendicular to the tibial plateau. A piece of metal is placed between the cut to maintain the position of this advancement while the bone also heals and fills in this expanded space. The tibial thrust (forward sliding moving) is neutralized within the stifle by changing the forces and having the stifle more parallel to the patellar tendon, causing engagement of the quadricep muscles.
All three of these surgical corrections involve general anesthetic and a recovery period. We recommend the use of a sling in the hind to help prevent slipping or falling. Icing may be used post surgical for 5-10mins multiple times a day for the first 48 hours after, then can be stopped. Gentle passive range of motions should be done multiple times a day to allow joint movement as well as muscle movement. On Veterinary Mobility Center’s website, you can find a video on how to do these passive range of motions (PROMs). Post op rehabilitation can start as soon as one week after to help with any pain/inflammation from surgical intervention, address secondary issues cause from the original issue, build up strength and improve functional movements.
Non-surgical Option – Orthotics
The use of an orthotic (brace) is a wonderful non-surgical and non-invasive option. Orthotics are also ideal for cases where there is both a ligament tear and extensive inflammation and or arthritic development has occurred by decreasing compression in the stifle joint. Orthotics provide stability to the stifle joint which allows the body time to organize scar tissue that will help provide stability as well as aid in appropriate muscle engagement and promote muscle strengthening. A cast impression of the leg is done as well as measurements and video/photo media taken. Casting is done without sedation. The impression, measurements and media are sent to a company in Denver, Colorado called Orthopets. A custom orthotic is fabricated within a couple weeks. Orthotics are worn during the day and are recommended being used during periods of activity (fetch, running, hiking, etc). After the initial break in schedule normal activities can resume with the use of an orthotic.