Cruciate ligament injury in the dog – what does it mean?

Kenilworth Vet
Cruciate injuries are one of the most common reasons for hind leg lameness and pain in the dog. Depending on the severity of the injury, surgical repair is usually required in order to stabilize the joint and reduce further damage. Your vet will probably have a preferred technique that he or she has used with success in which to do this.

Here is a straightforward explanation as to the function of the cruciate ligaments, why they sometimes rupture and the medical procedures that are usually used to correct the injury.

WHERE ARE THEY? WHAT DO THEY DO?
• the cruciate ligaments are two crossing ligaments that are situated inside the knee joint         (see diagram)
• their main function is stability of the joint; they restrict certain movements in the joint i.e.: hyperextension and internal rotation - movements that are beyond normal range

WHY DO THEY TEAR?
• normal aging causes degeneration of the ligaments
• breed deformities
• medical conditions that cause degeneration of ligament tissue
• direct trauma ‘sports injury’ is rare  

WHAT ARE THE SYMPTOMS OF CRUCIATE INJURY?
Symptoms can vary tremendously from sudden severe lameness to mild or moderate lameness. You may notice the following:
• difficulty getting up
• trouble jumping into the car
• decreased activity level
• decreased muscle on the affected hind leg
• sits with leg ‘out’

WHY IS IT SO IMPORTANT TO TREAT THIS CONDITION?
If the cruciate ligaments have partly torn or have completely ruptured the knee joint is no longer stable. The collateral ligaments are put under pressure and can tear causing further instability. Progressive degenerative changes such as osteoarthrtis occur within and around the joint, which can result in pain, discomfort and lameness in the patient.

Methods of Repair.
There are a variety of methods that can be used to stabilize the stifle (knee) joint after cruciate injury. TPLO or Tibial Plateau Levelling Operation and TTA Tibial Tubersoity Advancement are usually performed on very large breeds and often by a specialist surgeon.

The two below are more common techniques performed in general practice.

Extracapsular Stabilization
This involves the placement of a non-absorbable suture material being placed around the fabella. A hole is drilled in the tibial crest and the suture is passed through this hole and secured. (See diag) This method only provides temporary stabilisation and relies on the body to create scar tissue to ultimately stabilize the joint.  The suture material usually loosens with time and can break. the recovery period for this type of surgery can be anything from 3-5 months.

Cruciate injuries should not be ignored, if not dealt with timeously they can result in rapid degeneration of the joint and severe arthritis. So although it can come as a shock to know your dog needs surgery rest assured that your vet has your dog’s long-term well being at heart.

Tight Rope Technique
This is one of the latest procedures for treating this injury. A hole is drilled in the femur and a second in the tibia. A special ‘prosthetic ligament’ is then passed through the holes and secured. This method
of stabilization mimics a normal cruciate ligament, giving stability but allowing normal range of movement in the joint. Recovery from this type of surgery can be anything from 1 – 4 months.

Cruciate injuries should not be ignored, if not dealt with timeously they can result in rapid degeneration of the joint and severe arthritis. So although it can come as a shock to know your dog needs surgery rest assured that your vet has your dog’s long-term well being at heart.