Cranial Cruciate Ligament Rupture – Lateral Fabellar Technique (Extracapsular Technique)
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Article Written by Dr. Daniel A. Degner, Board-certified Veterinary Surgeon (DACVS)

Key Points

Cranial cruciate ligament rupture is the most common orthopedic condition of dogs and affects all breeds. Occasionally cats and ferrets develop the same problem

The cranial cruciate ligament is one of the main stabilizing structures of the stifle joint

The lateral imbrication technique has good outcomes in small breed dogs, but is not the best option in large breeds


Anatomy

  • The cranial cruciate ligament is one of the main stabilizing structures of the stifle joint (in man this joint would be called the knee). The cranial cruciate ligament serves to prevent forward movement of the tibia bone (shin bone) relative to the femur bone (thigh bone), to prevent internal rotation of the tibia bone, and to limit hyperextension of the stifle.
  • Two meniscal cartilages located inside of the joint are crescent-shaped pads that serve as cushions, provide stability to the joint, and help to push the nourishing joint fluid into the cartilage of the femur and tibia bones.
  • Several other ligaments also hold the stifle together, however, infrequently rupture in dogs.
  • To the right is a photo of the ligaments of the stifle joint as viewed from the front - the kneecap and patellar ligament have been removed; C=cranial cruciate ligament; M=medial meniscus.

 

Cranial cruciate ligament rupture

  • Cranial cruciate ligament rupture is the most common orthopedic condition that we treat and affects all breeds of dogs, and occasionally cats and ferrets.
  • The ligament may undergo partial tearing over a period of months, or may suddenly rupture during normal physical activity.
  • Most dogs are middle-aged or older when the rupture occurs, however some breeds such as Labrador Retrievers, Rottweilers, and Mastiffs may develop partial or complete tears when they are puppies.
  • The cause is unknown, but conformation of the limbs and genetics may play a role.
  • Partial ligament tears may be difficult to diagnose and frequently occur in both legs at the same time.
  • When the ligament tears, the stifle becomes unstable. The femur and tibia bones that form the joint then rub back and forth on each other (termed "drawer movement"). This results in pain due to stretching of the joint capsule, potential damage to the meniscal cartilage, and inflammation of the joint (called arthritis). In about half of the patients that we operate, the meniscal cartilage on the inner side of the joint (medial meniscus) has been torn and the damaged portion must be removed.

 

Candidates for the lateral fabellar surgery

  • This technique is used most commonly for small dogs and cats.
  • Large breeds of dogs have a better outcome when the tibial plateau leveling osteotomy (TPLO) is performed.
  • We have noted that dogs that have a steeply-sloped tibial plateau should receive the TPLO instead of the lateral imbrication technique regardless of their size. The lateral imbrication technique cannot overcome the forces on the stifle joint caused by a steep slope and frequently the nylon band will tear or loosen in the postop period.
  • All dogs that are going to have cruciate surgery should have a correctly positioned x-ray taken to measure the slope of the tibia so that an informed decision can be made on the appropriate type of surgery that should be performed. In my experience dogs that have a steep tibial slope (especially large breeds) do much better with the TPLO surgery. This may not be an important factor in small breeds even with a steep tibial slope, but the clients should be aware of the fact that a steep tibial slope will put much greater force on the nylon bands, therefore they may break.

      

Surgery

  • The stifle is surgically opened to examine the inside of the joint. We typically perform a mini-approach to the joint, which minimizes the healing time after surgery. The torn ends of the cruciate ligament are removed and the medial and lateral meniscus cartilages are examined for tears. 
  • 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.

      

  • If the medial meniscus is not torn, a prophylactic release of the caudal (back) pole of the meniscus is performed in order to help prevent a tear in the future.
  • Heavy suture material (monofilament nylon) is passed from the lateral fabella to the tibial crest and tied in order to eliminate joint instability (drawer movement). Place your curor over the image right to see the effect of the lateral imbrication technique.
  • With time, scar tissue develops around the stifle joint which helps to stabilize the joint.  The build up of scar tissue will also decrease the range of motion of the joint. 
  • An alternative to the using lateral fabellar technique is the tibial plateau leveling osteotomy. This is an excellent technique for large dogs, highly athletic dogs (hunting, agility), or show dogs. I prefer this technique over the lateral fabellar technique, as these patients recover quicker and develop less degenerative arthritis of the stifle.
  • The illustration right shows the implanted nylon bands which stabilize the joint.  The blue lines represent the nylon bands that are passed around the fabella bone (which sits on the back of the femur bone), and through a hole that has been drilled in the front part of the tibia bone.  The nylon bands pull the femur back into place on the tibia.

      

Contralateral cruciate tears

  • About one third of the dogs will also tear the cruciate ligament in the opposite limb.
  • These dogs frequently have arthritis in the knee joint even before the tear in the cruciate is obvious on physical examination, but early changes such as mild joint swelling may be detected with x-rays.
  • An x-ray may be recommended to predict if the opposite stifle joint is going to develop a tear.

 

Expected convalescent period

  • By 2 weeks after the surgery your pet should be touching the toes to the ground at a walk.
  • By 8 weeks the lameness should be mild to moderate.
  • By 6 months after the surgery your pet should be using the limb well.

 

Success rates

  • With the extracapsular technique, about 85% of the cases are significantly improved from their preoperative state. With the extracapsular technique, we can expect that 50% of these dogs will have some degree of lameness, whether it is mild or intermittent following heavy activity.  On the other hand about 50% regain normal function of the limb.
  • Even though this surgery may not return the limb to perfectly normal function, these dogs usually are greatly improved over their condition prior to surgery.
  • The lateral fabellar suture technique will not stop the progression of arthritis that is already present in the joint. As a result, your pet may have some stiffness of the limb in the mornings. In addition, your pet may have some lameness after heavy exercise or during weather changes.  To help with stiffness chondroitin sulfate and glucosamine may be given.

 

Potential complications

  • Anesthetic death can occur, but is rare
  • Infection at the surgical site
  • Sterile reaction to the nylon bands
  • Premature loosening or breakage of the nylon bands
  • If the meniscal cartilages were not found to be damaged at the initial surgery, it is possible that damage may occur at a later date, thus requiring a second surgery. The sign of a meniscal tear is a sudden onset of lameness.
  • Entrapment of the peroneal nerve by the nylon sutures is very painful and can result in permanent functional impairment of limb function.

 

Postop care

  • Ice pack the stifle three times daily, 10 minutes per session for the first 2 days to help reduce the swelling and pain.
  • Hotpack the stifle starting on the third day after surgery, 10 minutes per session prior to passive range of motion of the joint.  The hotpacking will soften the soft tissues prior to the range of motion of the joint and will make it less painful to do the exercise.
  • Passive range of motion of the joint involves flexing and extending the stifle joint, and should be done 10 minutes following the hotpacking. After the range of motion exercises have been completed, a cold compress is applied to the stifle for about 5 to 10 mintues.
  • The rehabilitation therapy should be done until your pet is bearing a significant amount of weight on the limb.
  • During the first two months activity is restricted to short leash walks outside.
  • Running, jumping, and rough play are forbidden.
  • Gradual increasing the activity during the third month after surgery allows for a safe return to function.
  • Unleashed activity can take place after four months.

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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  • Four years of advanced training in surgery beyond the Doctor of Veterinary Medicine Degree

  • Experience in the development of new surgical treatments

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  • Assurance that a veterinarian is a surgical specialist

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