Cranial Cruciate Ligament Disease
Cruciate Disease, Ruptured Cranial Cruciate Ligament, ACL Injury, Torn Cranial Cruciate Ligament, Partial ACL Injury, Tibial Plateau Leveling Osteotomy, Tibial Tuberosity Advancement, Lateral Suture Stabilization, Meniscal Tear
- 40-60% of dogs that have CrCLD in one knee will, at some future time, develop a similar problem in the other knee.
- Partial tearing of the CrCL is common in dogs and progresses to a full tear over time.
- difficulty rising from a sit
- trouble jumping into the car
- decreased activity level
- lameness (limping) of variable severity
- muscle atrophy (decreased muscle mass in the affected leg)
- decreased range of motion of the knee joint
- a popping noise (which may indicate a meniscal tear)
- swelling on the inside of the shin bone (fibrosis or scar tissue)
- unwillingness to play
- confirm the presence of joint effusion (fluid accumulation in the joint, indicating that there is an abnormality present)
- evaluate for the presence/degree of arthritis
- take measurements for surgical planning
- rule out concurrent disease conditions
- Osteotomy-based techniques require a bone cut (osteotomy) which changes the way the quadriceps muscles act on the top of the shin bone (tibial plateau). Stability of the knee joint is achieved without replacing the CrCL itself but rather by changing the biomechanics of the knee joint. This can be accomplished by either advancing the attachment of the muscle (Tibial Tuberosity Advancement (TTA)) or by rotating the plateau (slope) of the shin bone (Tibial Plateau Leveling Osteotomy (TPLO)). Many surgeons prefer these techniques for large, active dogs because of their consistent outcomes in even the most athletic of patients:
- Tibial Plateau Leveling Osteotomy (TPLO) involves making a circular cut around the top of the tibia and rotating its contact surface (tibial plateau) until it attains a near level orientation (approximately 90 degrees) relative to the attachment of the quadriceps muscles (Figure 2). This renders the knee more stable, in the absence of the CrCL. The cut in the bone needs to be stabilized by the use of a bridging bone plate and screws (Figure 3). Once the bone has healed, the bone plate and screws are not needed, but they are rarely removed unless there is an associated problem (irritation, infection).The perceived advantages of this compared to suture-based techniques are the superior outcomes attained in larger dogs relative to limb function and athletic mobility with less progression of arthritis.The major disadvantage is the need to perform an osteotomy. Any osteotomy requires healing of the bone, and if a problem is observed (such as implant failure, failure of the bone to heal), it may require revision surgery that may negatively affect short and long-term outcomes. Fortunately, such complications are rare, especially when the procedure is performed by an experienced board-certified surgeon.
- Tibial Tuberosity Advancement (TTA) requires a linear cut along the front of the shin (tibia) bone. The front of the tibia, called the ‘tibial tuberosity’ is advanced forward until the attachment of the quadriceps is oriented approximately 90 degrees to the tibial plateau (Figure 4). This is another way to accomplish the same mechanical advantage offered by the TPLO that renders the knee more stable in the absence of the CrCL. The TTA and TPLO share similar advantages and disadvantages. Similar to the TPLO, the cut in the bone is stabilized by the use of a specifically designed bridging bone plate and screws. The decision between TPLO and TTA is based purely on the opinion of your surgeon and their personal technical experience. To date, no published data supports one technique being superior to the other.
- Suture-based techniques can be divided into intra-articular (within the joint) and extra-articular (outside the joint) procedures. Because of the inconsistency of the results reported with intra-articular techniques in dogs, suture-based procedures are primarily performed in an extra-articular fashion. The most commonly performed technique is called extra-capsular suture stabilization, which utilizes suture material that is placed just on the outside of the knee joint (but under the skin) to mimic the stability offered by the CrCL. A variation of this technique is called Tightrope® and allows the surgeons to use bone tunnels for proper suture placement.
- Extra-capsular suture stabilization (also called “Ex-Cap suture,” “lateral fabellar suture stabilization,” and the “fishing line technique”) is a popular technique. While there are many variations of this technique, suture material used, and types of securing implants, the consistent goal is to “mimic” the function of the ruptured CrCL with a suture placed in similar orientation to the original ligament. The long-term goal is to facilitate the formation of organized scar tissue periarticular (around the joint) that will provide stability even as the suture gradually stretches or breaks. The most common complications after this procedure involve failure of the suture and progressive development of arthritis. The main risk factors for complications with suture-based techniques are patient size and age; larger and younger patients have more complications. For these reasons, many surgeons reserve suture techniques for small breed, older, and/or inactive dogs. The main advantages of this technique include its typically lower cost, lack of required specialized training to perform, and the lack of a bone cut.
- The Tightrope® is a novel “suture” technique that was developed as an alternative to osteotomy-based techniques. It utilizes a specifically developed suture/toggle implant that requires holes to be drilled through the thigh (femur) and shin (tibia) bones for more accurate anatomic placement of the implant (Figure 5).Advantages of this procedure over other suture-based techniques include more accurate placement of the implant and better “suture” strength. A study comparing TPLO and Tightrope® techniques did not find a significant difference between them relative to outcomes at 6-months after surgery.
- Activity restriction and anti-inflammatories – While administration of pain medications to dogs with CrCLD may improve their comfort, knee pain remains because of the persistent knee instability present. For this reason, strict activity restrictions (e.g., leash-based activities) are typically most effective at reducing pain in dogs with CrCLD. For these reasons, this treatment is generally limited to individual dogs in which surgery cannot be performed (i.e., financial constraints, illness, etc.)
- Rehabilitation therapy – There is ample evidence that therapy under the care of a veterinarian fully trained in physical rehabilitation can hasten and even improve the recovery from surgery. However, there is scant evidence to suggest that this is a consistent and predictable alternative to surgical management of CrCLD in dogs.
- Custom knee bracing/orthotics – Custom knee bracing is relatively new to canine orthopedics and there is no published data that supports it viability as a reasonable treatment in dogs with CrCLD. Much of the enthusiasm for dog knee bracing is extrapolated from their successful use in humans with ACL injuries. However, the mechanics of the canine and human knee are vastly different and it is unwise to make any comparisons between them relative to treatment modalities. At this time, there is not enough evidence to support any recommendation for knee bracing as a treatment of CrCLD.