Cranial Cruciate Ligament Rupture
Recently there have been many advances in the treatment of cranial cruciate ligament rupture. Dr. Slocum developed the cranial tibial wedge resection which led to the tibial plateau leveling osteotomy (TPLO) in the 1980s. This surgery was based on the concept of cranial tibial thrust which is cranial displacement of the tibia in relation to the femoral condyle during weight bearing. Because the tibial plateau is angled in relation to the femoral condyles, the patella tendon pulls the proximal tibia in a cranial direction and the gastrocnemius pulls the distal femur in a caudal direction during muscle contraction. The tibial plateau leveling osteotomy converts the tibial plateau to an approximate 6 degree angle which helps to neutralize these forces and therefore reduces stifle instability during walking. More recently the tibial tuberosity advancement (TTA) procedure has been developed. Instead of changing the tibial plateau slope, this procedure helps to neutralize cranial tibial thrust by changing the position of the patellar tendon so that it is perpendicular to the tibial plateau. When the tension across the patellar tendon is perpendicular to the tibial plateau, it does not result in displacement. One advantage of the TTA procedure over the TPLO is that the fracture created during surgery does not affect the weight bearing surface of the bone. This decreases early morbidity and there is less risk for varus/valgus abnormalities after surgery. A recent study in Veterinary Surgery (Lafaver, et al, volume 36, Aug 2007, Tibial Tuberosity Advancement for Stabilization of the Canine Cranial Cruciate Ligament-Deficient Stifle Joint: Surgical Technique, Early Results, and Complications in 101 Dogs) revealed that 74% of patients had no noticeable lameness after TTA surgery. Whereas 23 % had a mild lameness and only 3 % had a moderate to severe lameness long term.
All 3 procedures (routine extracapsular, TTA, TPLO) have distinct advantages and disadvantages. With the TTA animals tend to use their limbs very quickly after surgery. There are certain situations in which 1 procedure may offer an advantage over another procedure. One example is patients with patella alta. The patella is positioned in an abnormally proximal position which allows for laxity, luxation, and pain. The tibial tuberosity advancement procedure can be combined with distal displacement of the cranial tibial crest. This moves the patella in a more distal position which helps to prevent luxation. Another example is dogs which have a marked torsional or valgus/varus deformity of the tibia. The tibial plateau leveling osteotomy can easily be modified to correct these deformities. A third example is excessive tibial slope (>30 degrees). Since the tibial tuberosity can only be advanced a maximum of 12mm, the tibial tuberosity advancement may not adequately stabilize stifles with an excessive tibial slope. In these cases, the tibial plateau leveling osteotomy would most likely be preferred.
The lateral suture technique requires less specialized equipment and is less time consuming. Postoperative radiographs are usually not required. Therefore it costs less and provides a good alternative for clients with more limited funds. Furthermore there is less possible risks associated with this procedure than the TTA/TPLO.
Though there is much attention given to the newer procedures, the routine extracapsular (lateral suture) procedure is still performed commonly as well. For smaller patients (dogs and cats less than 25 lbs) results are usually very good. There is much controversy over the efficacy of the surgery for medium to large breed dogs. However, there is no study that clearly proves one procedure has better long term results than another study. One study (Lazar, et al: Vet Surg, volume 34, April 2005, Long-Term Radiographic Comparison of Tibial Plateau Leveling Osteotomy Versus Extracapsular Stabilization for Cranial Cruciate Ligament Rupture in the Dog) demonstrated less progression of osteoarthritis after TPLO surgery versus the routine extracapsular surgery. Even though people may disagree over the best procedure, the routine extracapsular repair still has its place in veterinary medicine. It is much less costly than the other procedures, it requires less anesthesia time, and provides good results in many patients.
Surgery is only 1 part of the treatment for cranial cruciate ligament rupture. The rehabilitation after surgery is another significant factor leading to a good outcome. A study in JAVMA (Marsolais, et al, May 2002, Effects of postoperative rehabilitation on limb function after cranial cruciate ligament repair in dogs) revealed greater function as measured by force plate analysis at 6 months after surgery for dogs which underwent rehabilitation versus surgery alone. A consult with someone trained in veterinary rehabilitation is recommended shortly after the surgical procedure. Pennsylvania Veterinary Specialty and Emergency Associates at Hickory Veterinary Hospital, has an in-house rehabilitation program.
The final decision as to which procedure is best suited to a specific
patient is based on the individual pet and a thorough conversation with
the owners. By offering all 3 procedures, we can better accommodate
each individual client and each individual patient.