Tibial Plateau Leveling Osteotomy - TPLO
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Article Written by Dr. Daniel A. Degner, Board-certified Veterinary Surgeon (DACVS)

Key Points

One of the important functions of the cruciate ligament is to prevent forward and backward sliding of the femur on the tibia bone, also known as drawer motion

Rupture of this ligament leads to debilitating lameness

The TPLO surgery compared to other techniques results in

  • a more rapid recovery

  • better range of motion of the joint

  • development of less arthritis

  • return to athletic or working activity

The TPLO surgery has a steep learning curve - choose an experienced surgeon for your companion


 

Introduction

  • The stifle joint (in layman's terms called the knee) of the dog is similar to a human’s knee. The cranial cruciate ligament is located inside the joint and is responsible for maintaining a stable joint. One of the important functions of the ligament is to prevent forward and backward sliding of the femur on the tibia bone (drawer motion).
  • Cranial cruciate ligament rupture is the most common orthopedic condition that we treat.
  • This problem afflicts all ages and breeds of dogs.
  • Frequently cruciate ligament rupture is a gradual process and not simply due to a single traumatic injury. Most dogs have a predisposing factor such as age-related ligament degeneration, pre-existing inflammation, anatomical abnormalities, and excessive slope of the top of the tibia bone, which cause the ligament to rupture.
  • Clinical signs of early cruciate disease includes stiffness or very mild lameness. As the disease advances and the ligament progressively tears, the lameness becomes more pronounced. Complete tears initially result in nonweight-bearing on the limb, but as time goes on the dog will start to use the limb. It is unusual that the lameness will resolve in a large breed dog with no surgery.
  • Rupture of the cruciate ligament in both knees is common. In fact, one out of three dogs will also develop a cruciate rupture of the opposite stifle.
  • Above is a photo of a front view of the stifle joint in a dog illustrating the cranial cruciate ligament (labeled C) and the front horn of the medial meniscus (labeled M), which is a cartilage pad located within the stifle joint that is commonly damaged with cruciate ligament tears.

      

Wagon Model Used to Explain Instability of the Knee Joint

  • The tibial plateau of a dog’s stifle is sloped.
  • Understanding the importance of the tibial slope when the cranial cruciate ligament is torn is somewhat difficult. We therefore present a model of a wagon on a hill, which is tied to a post.
  • The slope of the hill represents the tibial plateau, the wagon represents the femur bone, and the cable represents the cranial cruciate ligament.
  • If the cable is torn, the wagon will roll down the hill (see fig below). Likewise, when cranial cruciate ligament is torn the femur bone will slide down the slope of the tibial plateau.
  • When surface that the wagon is placed on is level and weight is put in the wagon, it does not to roll backward (see fig below).
  • In the dog, the tibial plateau leveling osteotomy levels the slope of the tibial plateau so that the femur no longer slides down the plateau. Thus a dynamically stable joint is created even when no cruciate ligament is present.


Tibial Thrust

  • When the cruciate ligament is ruptured, the slope of the tibial plateau, along with the forces exerted by the calf and quadriceps muscles cause the femur bone to slide down the top of the tibia bone called the tibial plateau. This in essence causes the tibial plateau to thrust forward with each weight-bearing stride and is called cranial tibial thrust.
  • This thrusting results in excessive wear of the cartilage of the joint. In addition, as the tibia thrusts forward it stretches the tissues which surround the joint, which causes pain.
  • Excessive cranial tibial thrust also can tear of one of the cartilage pads in the knee called the medial meniscus. This usually results in a meniscal bucket handle tear or crush injury.
  • The tibial plateau leveling osteotomy  or TPLO can eliminate cranial tibial thrust, thus creating a dynamically stable stifle and sound gait.

      

TPLO Surgery

  • The first part of the surgery involves removing the torn ends of the cruciate ligament and examining the medial and lateral meniscus cartilages. 
  • To the right is an illustration of the front view of the stifle; note the medial meniscus, the cranial cruciate ligament and the lateral meniscus
  • The medial meniscus is concurrently torn in about 40 to 50% of dogs that have a torn cruciate ligament.
  • When the femur bone shifts backwards the femur bone pinches the medial meniscus, causing it to tear from the back part of the stifle joint and flip forward. Put your cursor over the illustration to the right - take note that as the femur bone shifts backwards the back horn of the medial meniscus tears and flips forward.
  • A torn meniscus will make a patient much more painful than a cranial cruciate ligament tear alone. As the patient walks the torn part of the meniscus may flip back and forth resulting in a audible popping or clicking noise.
  • Every attempt is made to save as much of the normal meniscus as possible and only trim out the damaged portions of this structure. This is called a partial menisectomy. It is believed that partial menisectomy results in less arthritis than a complete menisectomy.

      

  • Arthroscopy can also be used to examine the inside of the stilfe joint. This technique can also be used to clean out the joint. This is a video of arthroscopy of a dog that has a minor tear of the cranial cruciate ligament. In this case, the cruciate ligament is preserved.

  • Additional images from arthroscopy of a stifle joint. Image below left of grossly normal meniscus (mild curl of the edge of the meniscus is normal). The image below right is a partially torn cruciate ligament
  • The tibial plateau leveling osteotomy - TPLO involves making a curved cut in the top of the tibia bone (osteotomy) to include the tibial plateau. The tibial plateau is then rotated along the curved osteotomy in order to level the slope. A plate and screws are used to hold the tibial plateau in place so that the bone can heal in its new position. Below left is radiograph of a stifle before TPLO surgery and below right is a radiograph demonstrating the curved cut in the tibia bone and rotation of the the tibial plateau. Take note of the metal plate and screws that hold the bone together. The tibial plateau should not be leveled to 0 degrees or less as this will strain and potentially tear the caudal cruciate ligament. One research study indicated that dogs that had a postop tibial plateau angle between 2 and 14 degrees clinically did very well, however the original recommendation by Dr. Slocum is 5 degrees.
preop rad postop TPLO rad

 

  • Take note of this radiograph which is a front view of the stifle after TPLO surgery has been completed. A plate, which has been manually contoured by the surgeon to the shape of the tibia bone, is fastened in place with six screws. It is critical to ensure that no screws penetrate through the top of the tibia bone into the stifle, as this will result in severe damage to the joint with resultant arthritis.
TPLO postop AP rad

   

  • Healing Phases Following TPLO surgery:
    • Unlike the convalescence from other extra-articular or intra-articular techniques, recovery from TPLO surgery frequently is more rapid and complete. In our experience, about 50% of the dogs will start to walk on the limb within 24 hours after surgery. Within 5 days after surgery most dogs will begin weight-bearing on the operated limb.
    • By 2 weeks after surgery, a moderate amount of weight-bearing can be expected. Dogs with partial tears tend to recover quicker than dogs having complete ligament tears. We have seen some dogs having partial tears recover to near full weight-bearing within 2 weeks after surgery…this is phenomenal, as we have never seen this type of a recovery with any of the other surgical techniques that are used to stabilize the knee.
    • Radiographs taken at 6 to 8 weeks postop should reveal healing of the osteotomy site.  At this time most dogs have mild or no lameness; when we evaluated our patients having TPLO, the average time for the lameness to resolve was 10 weeks.
    • At 2 months after surgery, exercise in the form of leash walks should be gradually increased each week. Increasing the number of walks per day tends to be better than just increasing the duration of each period.
    • At 4 months after surgery most restrictions of exercise can be lifted. Full working activities (hunting, agility, etc) can begin at 6 months after surgery. Unconstrained activity prior to this time can cause spraining of the soft tissues of the stifle (patellar ligament sprain) resulting in a prolonged recovery.
  • Yearly radiographs of the stifle should be taken to evaluate the degree of arthritis. The TPLO procedure should minimize the progression of degenerative joint disease.  One study indicated a trend to a slower progression of arthritis following TPLO surgery, versus dogs that received the lateral imbrication technique, however arthritis usually will develop regardless of technique.
          

Success              

  • One of the best things you can do to help your dog achieve a successful recovery is to follow the recommendations by a trained therapist. In addition, to learning what you can do at home, consider finding a canine rehabilitation facility in your area.
  • A successful outcome will return your dog to full function on the limb.  In my experience, about 90% of the dogs having the TPLO regain normal or near normal function of the limb (full weight-bearing); this information is based on a retrospective survey that we conducted on our patients.  The remaining 10% of dogs have concurrent arthritis in other joints of the operated limb or advanced degenerative joint disease in the stifle; most of these dogs in this group are still helped by the surgery.
  • We have found that most working dogs will return back to full working function. 
  • Dogs that have sustained a blowout fracture of the tibial plateau as a complication of falling after surgery may have residual stiffness or lameness.
  • Dogs that have been previously operated using another technique frequently are improved with the TPLO surgery, but the outcome may not be as good, versus a virgin knee that has received the TPLO surgery. 

Potential complications

  • As with any surgery, complications may arise. Even though rare, anesthetic death can occur. With the use of modern anesthetic protocols and extensive monitoring devices (blood pressure, EKG, pulse oxymetry, inspiratory and expiratory carbon dioxide levels, and respiration rate), the risk of problems with anesthesia is minimized.
  • Infection is an unusual complication as strict sterile technique is used during the surgery and antibiotics are administered during the procedure.
  • Poor healing of the bone can occur if the pet is too active, especially during the first 2 months after surgery. If steroids are given to a pet for reasons such as skin allergies, healing of the bone may be severely impaired. Breakage of plates or screws or backing of screws out of the bone can occur if activity is not limited during the first 2 months. Even after the bone has healed, the soft tissues need to also heal.
  • If activity is unleashed prematurely, straining of the patellar ligament can occur. Rest and anti-inflammatory medication is used to resolve this problem.
  • Fracture of the narrow front part of the tibial crest can occur. This is not common, and usually will heal without any surgical intervention.  Recovery will be delayed, but the final result still should be very good.
  • A blow-out fracture of the tibial plateau has been seen in 0.4% of the cases (in a series of 700 cases) at our hospital.  The cause of this is due to the dog falling on the stifle after surgery.  Reoperation is performed in these cases.
  • Loosening of the screws with shifting of the slope of the plateau may occur if the pet is not restricted during the healing phase.  If the plateau has shifted a significant amount reoperation is performed.  This complication is more common in the giant breed dog, as a result we generally use a larger TPLO plate and 8 screws, instead of the standard sized TPLO plate and 6 screws to help prevent this problem. 
  • It has been reported that dogs that have a very steep tibial slope (greater than 35 degrees) are at greater risk of having complications (shifting of the bones, fracturing of bones, loosening of implants). However, once the healing had taken place the function of these dogs too was very good and client satisfaction was usually very good.
  • A bone cancer can develop in the tibia bone due to the presence of the surgical implants (bone screws and plate), however, this complication is rare. Removal of the plate after healing takes place may help to prevent this complication. Because the formation of this tumor is so uncommon, there is no study available that has truly shown that removing the implants is helpful.
  • Arthritis usually is present at the time of surgery and will progress to some degree regardless of treatment or no treatment. Unfortunately we cannot reverse the arthritic and degenerative state of the joint, but the surgery may help to minimize the progression of this. I have seen cases receiving the TPLO surgery that have developed minimal arthritis years later, yet other cases have developed a lot of arthritis as seen on x-rays. Just because arthritis may be seen on x-rays does not mean that your dog will be lame on the limb. Warning signs of clinical arthritis include stiffness associated with heavy exercise and cool damp weather. Anti-inflammatory medications are useful to ameliorate a flare-up of arthritis.
  • Tearing of the meniscus (cartilage pad in the knee) may occur following TPLO surgery and additional surgery would be needed. This complication occurs less frequently following the TPLO versus when other surgical techniques used to stabilize the stifle joint.

 

Tibial Tuberosity Advancement or TTA Surgery

Frequently Asked Questions After Surgery

When should my dog have the first bowel movement after surgery?

  • Many dogs will not have a bowel movement for the first 4 to 5 days after surgery
  • Reasons that a dog will not have regular bowel movements after surgery include:
    • The dog has been fasted prior to surgery
    • Dogs do not eat well during the hospital stay
    • They frequently do not eat well when they go home
    • They are fed highly digestible food that produces little stool
    • Pain medication that contain narcotics (such as morphine, fentanyl patches, and tramadol) can be constipating
  • If a pet does not have a bowel movement on the 5th day of being home, a stool softener such as metamucil can be fed
    • Dose of metamucil is 1 tsp per 25 Kg mixed in with each meal (canned dog food); feed immediately after mixing, as the metamucil will gel the food and may make it less palatable

My pet had surgery and will not eat.  What can be done?

  • Dogs
    • Most pets will not eat their regular dog food after surgery, especially if it is kibble.
    • Offer a cooked diet having a 1:1 ratio of a protein source and carbohydrate source.  The protein source can be any meat (example: chicken breast, turkey breast, lean hamburger) that is low in fat and should be cooked (drain off all fat after the meat has been cooked).   The carbohydrate can be pasta, potato or white rice.
    • Try canned dog food; to enhance the flavor sprinkle a very small amount of garlic powder or chicken or beef broth (Chicken-in-a- MugTM or Beef-in-a-MugTM products)
    • Try Gerber strained meats for babies such as the chicken, beef, turkey, or veal
    • Try Hill's A/D diet available at most veterinary hospitals
    • Hand feeding: place a small amount of food in the mouth so that your dog gets the flavor
    • Warm the food slightly in a microwave, as the food will be more aromatic; stir the food before feeding and test the temperature on the bottom side of your wrist; it should only be luke warm.
    • Remember that most pets will not eat the first day or two after they get home from surgery
  • Cats
    • Offer smelly foods that contain fish such as tuna or smelly cat foods
    • Try Gerber strained meats for babies such as the chicken, beef, turkey or veal
    • Hand feeding:  with your finger place a small amount of food on the roof of your cat's mouth; use a syringe to get soft food into the mouth
    • Warm the food slightly in a microwave as the food will be more aromatic; remember to stir the food before feeding and test the temperature; it should be only luke-warm
    • Some cats will only eat dry food, try kibble if your cat normally has been fed that food
    • Petting and stroking your cat frequently will help to stimulate appetite
    • Remember that most pets will not eat the first day or two after they get home from surgery
    • Appetite stimulants such as cyproheptadine may be helpful
    • If your cat refuses to eat anything for 7 days a stomach tube or nasogastric tube should be placed to provide nutrition so that a serious liver problem (hepatic lipidosis) does not develop

My pet is vomiting.  What can be done?

  • The first thing for you to discern is whether your pet is vomiting or regurgitating.  Both will result in fluid or food being brought up.  Vomiting always will have heaving or retching of the abdomen prior to expulsion of the vomitus.  Regurgitation is not associated with heaving and the pet usually just opens the mouth and fluid or food will be expelled.  Usually the regurgited material will be clear or brown colored fluid. 
  • Next is to identify the cause of the vomiting or regurgitation.
  • Causes and treatment of vomiting after surgery
    • When some pets return home after a stay in the hospital they may drink excessive amounts of water at one time and then vomit; if this appears to be the case, the water should be limited to frequent smaller amounts.
    • Medications such as antibiotics, narcotics or nonsteroidal anti-inflammatory medication commonly cause vomiting after surgery.  In order to see which medication is causing the problem, the administration of each drug should be separated 2 hours apart.  Usually the pet will vomit or appear nauseated (drooling and sick look) within 1 hour of administration of the medication that they are sensitive to.  The antibiotic in some cases may be changed to a different one, or may be discontinued. 
    • Stomach upset from anesthesia is a potential cause of vomiting and will pass within a couple of days. 
    • An uncommon cause of vomiting after surgery is internal organ failure.  Blood testing will confirm this problem. For this reason vomiting should not be ignored if it persists for more than 24 hours.
    • If your pet had surgery of the bowels or stomach, vomiting is always a concern, as it may indicate that infection of the abdominal cavity, called peritonitis, is present.  Do not ignore this sign.
    • Symptomatic treatment of vomiting involves withholding food for 12 to 24 hours, then introducing small amounts of bland food such as rice and lean cooked hamburger, if your pet does not vomit after that then gradually wean him/her back onto the regular diet after 3 days.  In order to decrease the acidity of the stomach, Pepcid AC 0.5 mg/kg can be given by mouth twice daily for 5 days.  Metoclopramide and Cerenia are good anti-vomiting medications for dogs and cats.  You should always consult a veterinary healthcare professional before administering medication.
  • Causes and treatment of regurgitation after surgery
    • The most common cause of regurgitation is reflux of acid from the stomach into the esophagus while your pet is under anesthesia.  Acidic fluid from the stomach can cause a chemical burn of the esophagus and result in a bad case of heart burn, called esophagitis.  This results in poor motility of the esophagus, therefore water and food will accumulate in this structure.  In most cases, esphagitis is self-eliminating and will resolve within two or three days. 
    • If the esophagitis is severe the esophagus may develop one or more strictures.  A stricture is a narrowing or stenosis of the esophagus and does not allow passage of food down the esophagus, in regurgitation that lasts longer than one week.  This problem should be brought to the attention of your pet's doctor within the first two weeks so that it can be treated by ballooning the stricture (minimally invasive procedure, as it is done with the aide of an endoscope).  If an esophageal stricture is chronic surgery is needed.
    • Symptomatic treatment of regurgitation caused by esophagitis includes feeding bland food, and administering a coating agent (sucralfate) and an acid blocker (omeprazole or other).  Consult a veterinary health care professional if the regurgitation continues for more than a couple of days.

How do I know that my dog is in pain following surgery?

  • Signs of pain include
    • crying
    • biting if you get near the surgical site
    • grimacing (lips are pulled back and the the dog looks anxious)
    • tragic facial expression
    • panting
    • restlessness and unable to sleep; pacing
    • if abdominal surgery was done the pet will not lie down on the incision, or will continually sit up in spite of appearing very tired
    • the worst pain will be for the first 2 to 3 days after surgery

What can I do to control my dog's pain?

  • Narcotic medications that control pain: tramadol, butorphanol, Duragesic (fentanyl patch)
  • Anti-inflammatories used to control pain: Deramaxx, Rimadyl, Previcox, or Etogesic
  • If an orthopedic surgery has been done cold packing the surgical site may be helpful
    • A cold pack may be a pack of frozen peas, crushed ice in a Ziploc bag, or a cold gel pack; place a thin barrier between the skin and the cold pack.  An alternative to a cold pack is to freeze water in a styrofoam cup; after frozen cut the bottom of the styrofoam cup out. Cool the surgical site around the incision by rubbing the exposed ice directly on the skin in a circular pattern.  Cooling the surgical site helps to numb the area.

How do I know that my cat is in pain following surgery?

  • Pain is more difficult to assess in cats versus dogs, as signs can be more subtle and they usually do not vocalize when in pain
  • Signs of pain in a cat include the following:
    • biting if you get near the surgical site
    • growling or deep cry
    • not wanting to eat
    • hiding and not wanting to be near owner (remember that this could also be caused by the cat just being upset about leaving home and coming back)

What can be done for pain at home for my cat?

  • Pain medication such as buprenorphine or a Duragesic (fentanyl) patch
  • Tylenol will kill a cat as they lack abundant glutathione enzyme in the liver
  • Anti-inflammatories can be used, but the dose is much less than dogs

Is it okay for my pet to lick the incision?

  • If a dog licks the incision, the healing process may be delayed.
  • Licking can remove stitches and cause the incision to open
  • Licking can become a severe habit that is difficult to break
  • Licking can cause infection as the mouth has many bacteria
  • Dogs will frequently lick the incision when the owner is not watching such as at night time; if the skin looks red or excoriated the most common cause is from licking.
  • To stop your pet from licking the following can be tried:
    • Elizabethan collar can be placed on the neck; this will not help stop your pet from scratching at the region
    • Cervical collar (bite not collar) is a less awkward device and can be effective at stopping a pet from licking the surgical site
    • A tee shirt can be used to cover an incision on the chest or front part of the abdomen; gather the waist of the shirt up over the dog's back and wrap an elastic band around this part of the shirt.
    • A bandage or sock can be used to cover an incision on a limb; fasten the top of the sock to the dog's limb with tape.
    • Bitter apple can be applied around the incision; many dogs will continue to lick  after application of this topical
    • Bitter Apple and Liquid HeetTM (obtain this from a drugstore...it is used for sore muscles) mixed in a 2:1 ratio can be applied around the skin incision
    • Antipsychotic medication in some cases is needed

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