Tibial Plateau Leveling Osteotomy (TPLO)

About ACL/CCL

The cranial cruciate ligament (CCL), equivalent to the anterior cruciate ligament, or ACL in people, is responsible for limiting hyperextension of the stifle, limiting internal rotation of the tibia in relation to the femur, and to prevent forward sliding/drawer motion of the tibia in relation to the femur. Cranial cruciate ligament rupture (CCLR) is the most common cause of hind limb lameness in dogs.

The underlying cause of CCLR in the majority of dogs is different than ACL injuries in most people. Whereas trauma is a common cause of ACL tears in people, CCLR in dogs is typically degenerative in nature. Some proposed predisposing factors for cruciate injuries in dogs include genetics, obesity and poor fitness level, early neutering, excessive tibial plateau slope (TPS), immune-mediated disease, and bacterial presence within the joint. Young to middle-aged, female, large breed dogs are at greatest risk for tearing their CCL, though any dog can develop a CCLR. However, as with ACL tears in people, acute traumatic ruptures can also occur.

Though the underlying cause of the disease may be different in each dog, the anatomy of the joint may play a role in the continued breakdown of the ligament. Due to the slope of the top of the tibia, or the tibial plateau, the cranial cruciate ligament of the dog is under stress during weight bearing as it attempts to keep the femur and the tibia in appropriate alignment. Once the integrity of the ligament is compromised, the tibia begins to move forward in relation to the femur during weight bearing. There is some evidence that the steeper the tibial plateau slope, the greater the likelihood of a dog developing a CCLR. The instability that develops is partly responsible for the pain present in dogs with this injury. As the cruciate ligament tears, changes are also taking place in the joint leading to a loss of cartilage health early on and a complete loss of cartilage in end-stage arthritis. In most patients, once the degenerative process of the CCL begins, the ligament will go on to a complete tear.

There are multiple tests your veterinarian can perform to help diagnose a cranial cruciate ligament tear. One of the first signs present prior to instability may be pain with full extension (hyperextension) of the knee. This pain is likely due to stretching of the intact or strained fibers of the cruciate ligament. Once the ligament tears to a certain degree the tibia can be manually manipulated to show instability in what is called the “cranial drawer test” in which the tibia can be moved forward in relation to the femur. Another sign referred to as tibial thrust, may be elicited as well. With this test, weight bearing is mimicked and the front of the tibia can be noted to be pushing forward in relation to the femur. It is important to keep in mind that many patients with clinical signs of pain and lameness may have a partial tear of the CCL. In these cases, there may not be any obvious instability (cranial drawer or tibial thrust) on the exam, however, the patient has a torn CCL that will likely progress to a complete tear.

Other signs that may be noted on the physical exam include loss of muscle mass (atrophy), detection of effusion (swelling) within the joint, and scar tissue formation around the knee (buttress). This scar tissue is the body’s natural response to try and stabilize an unstable joint. Long-term this scar tissue leads to a decreased range of motion in the knee. Finally, a “clicking” sound may be noted in a small percentage of patients with meniscal tears.

Though the cranial cruciate ligament is not visible on an x-ray, radiographs can help confirm a diagnosis of a CCLR by detection of changes that occur in the joint following CCL injury. These changes may include effusion (excess fluid in the stifle), arthritis, and forward movement of the tibia relative to the femur. Radiographs can also help rule out other concurrent injuries.

Rehabilitation

  • Walks are best performed on a short leash. Go slowly at first to help gradually improve strength. Walking slowly may help encourage use.
  • Walks can be done three to five times per day for five minutes at a time for elimination purposes.
  • Using a sling or folded bath towel under your dog’s belly can be used for support when walking on slick surfaces such as tile or wood floors, and even on other surfaces if they are unsteady on the surgical limb. The sling can also be used to help slow your pet’s pace down if they are pulling hard on the leash.
  • No off-leash activity
Range of Motion Exercises:
  • Lay pet on their side with surgical limb up.
  • Flex and extend the joints of the affected limb gently to resistance.
  • Gently support the knee to prevent twisting or rotation of the limb.
  • Repeat 2 – 3 times daily for 10 to 15 repetitions.
  • PROM should not cause pain, discomfort or negative reaction.

Ice and Heat Therapy

  • Use of ice packs after walks and PROM for the first 3 to 4 days after surgery.
    • Drugstore packs, crushed ice in a Ziploc bag, or frozen peas or corn can be used.
    • Ice around as much of the circumference of the knee as possible.
    • While a paper or thin towel can be used to absorb moisture from the ice pack, a thick towel may prevent icing from being effective.
    • Ice for 15 minutes per session.
  • Use heat packs prior to PROM after initial 3 to 4 days.
    • Drugstore packs or socks filled with uncooked rice heated in a microwave work well.
    • Test pack on your wrist first. If it is too hot for your skin, it is too hot for your dog.
    • Insulate the heat pack with a thin cloth.
    • Use for ten minutes per session.
  • If your pet fails to begin using his leg during the first two weeks, please contact your veterinarian.
  • A recheck should be performed at two weeks so the incision site can be evaluated. Sutures or staples are typically removed at the 10-14 day recheck.
  • Range of Motion can be reduced to twice per week.
  • Continue ice therapy as needed if your pet seems sore after walking/exercise.
  • Increase leash walks to ~8 minutes in week 3 and ~10 minutes in week 4 as long as your pet is using the surgical limb.
  • Incorporate the following exercises into leash walks as directed by your veterinarian, to build strength and body awareness:
    • Walk in large figure 8 pattern
    • Stepping slowly up onto and down off of a curb in an S pattern
    • Gentle inclines (a mild slope on a street or a driveway)
  • The following exercises can also help build balance and core strength. Perform these exercises on a non-slip surface, with 5-10 repetitions each
    • Gently nudge the hind end from side to side while standing
    • Sit to Stand exercise – have your pet repeatedly sit down, then stand up
    • Three-Legged Standing Exercise – Have your dog in a standing position, then lift one leg off the ground at a time for 10 to 15 seconds (alternate with all but surgical leg)
  • No off-leash activity
  • Icing and heat-packing can be discontinued
  • Continue performing the previously mentioned exercises
  • Week 5 increase length of walks up to ~12 minutes up to 3-5 times a day
  • Week 6 increase length of walks up to ~15 minutes up to 3-5 times a day
  • Week 7 increase length of walks up to ~18 minutes up to 3-5 times a day
  • Week 8 increase length of walks up to ~20 minutes up to 3-5 times a day
  • No off-leash activity
Radiographs will be taken at about 8 weeks to confirm appropriate bone healing. Assuming the tibia is healing:
  • Continue performing the previously mentioned exercises
  • Continue to gradually increase the duration of the walks
  • Gradually introduce off-leash activity, starting week 9 with about 5 minutes of off-leash activity 3-5 times a day, week 10 up to 10 minutes of off-leash activity 3-5 times a day, week 11 up to 15 minutes of off-leash activity 3-5 times a day, week 12 up to 20 minutes of off-leash activity 3-5 times per day.