This can be repaired using the following procedures:
Cranial cruciate ligament tears are the most common orthopaedic injury in people (ACL) and in dogs (CCL). The cranial cruciate ligament sits inside the knee joint and stops the shin bone (tibia) sliding forward in relation to the thigh bone (femur). When the ligament tears there is a cranial drawer (forwards and backwards sliding) between these bones. It is this movement which causes dogs pain and persistent limping. The degree of movement is related to the amount of tearing of the ligament and the angle of the articulating surface of the shin bone, called the tibial plateau angle. The steeper the angle the more forces are acting on the knee.
Unfortunately, approximately 50% of patients that tear one cranial cruciate ligament are at risk of tearing the other ligament at some point in the future and the goal is to return patients to normal weight bearing as soon as possible to reduce the strain on the remaining knee and ligament.
Approximately 30% of patients that present for tears of the cranial cruciate ligament will injure the meniscus which are the knees shock-absorbers. If the meniscus are injured at the time of surgery then the damaged portion is removed, whilst in patients that do not have a tear the meniscus is left intact as it is important to joint function. There is however an approximately 10% risk of an injury to the meniscus at a later date. This generally appears as a patient that has recovered well from surgery and then starts to limp on the leg, generally 1-6 months later. Should this occur then re-examination would be advised, and this may be treated by either arthroscopic or open surgical removal of the damaged meniscus, with quick recoveries and outcomes.
Without stabilisation of the cranial drawer movement, pain and discomfort will persist, it may slightly improve with rest but will again become painful with activity. Osteoarthritis will progress without intervention and surgery.
There are many different techniques which have been used to stabilise the dogs knee following tearing of the cranial cruciate ligament over the years, although broadly speaking there are 2 main groups. Group 1 changes the weight bearing forces through the knee, by cutting and rotating the shin bone, so that the patient is able to bear weight without the need for a cranial cruciate ligament (TPLO, TTO, CWO, TTA). Group 2 attempts to mimic what the cruciate ligament does using sutures (DeAngelis Suture, Isometric Sutures).
Ideally, the larger the patient or those with a steep angle inside the knee benefit from the surgeries in Group 1, whilst smaller dogs may cope with the surgeries from Group 2.
London Veterinary Services uses a Tibial Plateau Levelling Osteotomy (TPLO) in larger dogs or Cranial Wedge Osteotomy (CWO) in smaller dogs to alter the angle of the articulating surface of the shin bone to be more perperidicular to the downward force through the leg. The benefit of these procedures is that it allows earlier return to function, and also less osteoarthritic changes as determined by x-rays later in life, compared to the ‘suture techniques’. This group of techniques is the current gold-standard for cranial cruciate ligament injury in dogs. Following surgery, it is expected that over 90% of patients will have a good to excellent outcome.
London Veterinary Services uses Synthes Locking TPLO plates which minimise complications compared to standard plates.
Cruciate Repair TPLO Discharge Form (PDF)
The suture techniques may be used in patients who have a smaller body weight and relatively shallow angles within the knee joint, or where finances do not allow stabilisation using the bone cut techniques. London Veterinary Services uses surgical nylon to perform either DeAngelis Suture or Isometric Suture placement.
Complications rates fortunately are very low, with the most common complications being infection (2-4%), usually only requiring antibiotics additional to the ones dispensed at the time of surgery. A smaller number of cases where the joint or plates are infected, require flushing of the joint or removal of the plates via a short simple procedure. Generally, the implants never need to be removed and cause no problems.
DeAngelis Extracapsular Suture Tibial Tuberosity Advancement (PDF)
The TTA technique was developed on the basis of several observations and simple biomechanical analysis of the canine knee joint:
EXECUTION:The TTA involves an osteotomy of the non-weight bearing portion of the tibia. The patellar ligament is aligned perpendicularly to the common tangent of the femorotibial joint, eliminating cranial tibial thrust. This new alignment eliminates the need for the CrCL and results in a stable joint.
TTA vs. TPLOSince its clinical introduction, TTA has been mostly compared with the Tibial Plateau Leveling Osteotomy (TPLO). The January 2009 issue of Veterinary Surgery gives the most in-depth comparison of the two techniques in a review article: Boudrieau, RJ – Tibial Plateau Leveling Osteotomy or Tibial Tuberosity Advancement? Vet Surg 38: 1-22, 2009.
Some of the key differences are:
Advancement of the patellar ligament insertion point on the tibia increases the lever arm of the dominant active force at the stifle, leading to a general reduction of all reaction forces, including those between the patella, femur, and the tibia.
In contrast, TPLO causes a cranial shift of the femur, i.e. closer to the insertion point of the patellar ligament. This shift reduces the lever arm and thus increased force is required to extend the leg. Inflammation of the patellar ligament, frequently seen in TPLO, may be an indication of an increased force required to keep the joint balanced. Increased patellar ligament force, increases joint reaction forces and elevates the risk of cartilage degeneration. In view of these arguments and the apparent lack of patellar ligament inflammation in TTA, progression of joint disease may be slower than reported in TPLO.[2]
A more obvious, though generally overlooked, difference is that TPLO intervention places the stifle into increased flexion by the amount of the plateau rotation, i.e. by some 20 degrees. Joint congruity at near full flexion must be compromised, not the least in the region of the caudal meniscus. Whether the meniscus is released at surgery, as instructed by Slocum, or through the wear and tear of its use, reduced fluid sealing function is bound to lead to cartilage degradation.
TTA does not effect joint congruency. However, it does increase the loading of the caudal cruciate, although to a lesser extent than TPLO. This is partially offset by general reduction of internal joint reactions due to the now longer patellar ligament lever arm.
On balance, TTA is expected to provide a further improvement in long-term joint function, although to date there is no definitive data proving this.
Cranial cruciate ligament tears are the most common orthopaedic injury in people (ACL) and in dogs (CCL). The cranial cruciate ligament sits inside the knee joint and stops the shin bone (tibia) sliding forward in relation to the thigh bone (femur).
When the ligament tears there is a cranial drawer (forwards and backwards sliding) between these bones. It is this movement which causes dogs pain and persistent limping. The degree of movement is related to the amount of tearing of the ligament. Surgery to stabilise the knee will have been performed and the structures inside the knee (cranial cruciate ligament, caudal cruciate ligament, lateral and medial meniscus, and the articular cartilage) will be examined and “cleaned up” if found to be damaged at the time.
Approximately 30% of patients that present for tears of the cranial cruciate ligament will also have an injury to the shock-absorbers inside the knee (lateral and medial meniscus). If the meniscus are injured at the time of surgery then the damaged portion is removed, whilst in patients that do not have a tear the meniscus is left intact as it is important to joint function.
There is however an approximately 10% risk of an injury to the meniscus at a later date. This generally appears as a patient that has recovered well from the initial knee surgery, and then starts to limp on the leg generally 1-6 months later. Should this occur then re-examination would be advised, and this may be treated by either arthroscopic or open surgical removal of the damaged meniscus, with quick recoveries and outcomes to pre-injury levels expected.
Osteoarthritis will progress but the rate following surgery should be slowed, if compared to patients that do not have surgery. Management of longer-term osteoarthritis should be focused on body weight control, joint supplementation (fish oils, glucosamine/chondroitin, pentosane polysulphate injection), anti-inflammatories as required, and moderation of exercise.
Complication rate fortunately are very low, with the most common complications being infection (2-4%), usually only requiring antibiotics additional to the ones dispensed at the time of surgery.
Cruciate Repair TTA (PDF)