Canine Cruciate Ligament Rupture

Preoperative x-ray appearance of a stifle with a ruptured cranial cruciate ligament. Click to enlarge

Who is usually affected?
-Young to middle aged larger breed dogs
-Most frequently affected breeds include Labrador retrievers and Rottweilers

What is happening?
-The ligament that provides the most stability to the knee (stifle) during weight bearing (cranial cruciate ligament) weakens due to partial or complete tearing, the cause of which is generally unknown
-A cartilage pad on the inside of the knee (medial meniscus) may also be torn or flipped
-Inflammation and pain result from the altered joint mechanics and cartilage destruction
-Arthritis develops

Clinical signs you might notice in your pet
-Stiffness or limping in a hind leg, particularly after heavy exercise and/or prolonged periods of rest
-Limping becomes more constant as time passes
-Sitting with a hind leg off to the side
-Intermittent "clicking" noise when walking

Diagnosis
-Orthopedic examination to determine the joint(s) affected and to identify abnormal joint motion (cranial drawer motion, cranial tibial thrust)
-X-rays to evaluate the stifle region for swelling and arthritis
-Sedated examination is sometimes necessary to demonstrate abnormal stifle motion (sedation causes patient relaxation and allows the most thorough assessment of joint motion)

Postoperative x-ray appearance following tibial plateau leveling osteotomy Click to enlarge

Surgical treatment
-The cranial cruciate ligament cannot be repaired or replaced in dogs with good success, so the stifle must be stabilized with other methods that include: -Extracapsular stabilization-the function of the cranial cruciate ligament is mimicked outside the joint capsule with heavy suture that crosses the joint (lateral fabellotibial suture) or by repositioning another ligament that spans the joint (fibular head transposition); natural joint capsule thickening during the recovery period adds strength to these repairs
-Tibial plateau leveling osteotomy/TPLO-the need for the cranial cruciate ligament is eliminated by rearranging the angle at which the bones of the stifle joint meet during weight bearing; this is accomplished by cutting the tibia bone, rotating its top portion, then applying a bone plate
-The meniscus is usually addressed in combination with both methods via removal of damaged portions or "release" of healthy meniscus to help prevent future problems

Special postoperative care
-Patient activity is strictly limited until adequate initial healing occurs (expect 6-8 weeks) followed by gradually increasing activity over another 4-8 weeks
-X-rays may be taken at specific intervals to evaluate healing
-Physical therapy may be prescribed during the rehabilitation period

Expected results after surgery
-Much improved to normal weight bearing is ultimately expected with both types of surgery, most patients have a faster return to weight bearing with the TPLO
-Arthritis progression is slowed with both types of surgery, most patients have less accumulation of arthritic changes with the TPLO
-Due to the non-traumatic nature of this problem, there is a significant chance (35- 60%) that the opposite cranial cruciate ligament will rupture as well