The Small Animal Orthopaedics world is an odd one. An example of this is seen in some recent presentations and publications that suggest that Tibial Tuberosity Advancement is a procedure associated with a high complication rate. Whilst Andy was lecturing on Tibial Tuberosity Advancement at London Vet Show last year, another speaker at the Show was explaining how in his experience Tibial Tuberosity Advancement is a technique that results in a large number of serious post operative complications.
Whenever someone publishes their complication rate for a surgical procedure, they are either making comments regarding the safety of the procedure itself or their own ability to perform the surgery competently or safely. If a procedure is unsafe (i.e. intrinsically flawed due to a direct association with post operative complications) then this would be the universal experience. In other words if the procedure itself is unsafe, then the surgeon’s competence is not the major variable.
At Torrington Orthopaedics we have performed over 2000 Tibial Tuberosity Advancement procedures in patients from 8 months to 15 years old and in a broad spectrum of breeds. We would not have done this many procedures if we had experienced a high complication rate. So for clarity here is a breakdown of the complications seen in those 2000 patients at Torrington Orthopaedics:
- Tibial Diaphyseal Fracture (fracture of the shaft of the tibia): 1 patient (0.05%).
- Tibial Tuberosity Fracture (fracture of the tip of the tibia): 10 patients (0.5%).
- Plate Breakages: 0 patients.
- Cage Breakage: 1 patient (0.05%).
- Late Septic Events: 10 patients (0.5%). Nine of these patients had Septic Arthritis rather than implant associated sepsis.
- Late Meniscal Injury: currently 3% in past 18 months.
These surgeries were performed by six different surgeons between 2008 and 2016. We have all been trained on Kyon Tibial Tuberosity Advancement courses, plan meticulously prior to every surgery, follow the plan through to execution of the surgery and use only Kyon implants. We believe that these are the keys to successful application of this procedure. In our hands it is a powerful and effective method for managing Cranial Cruciate Ligament pathology in dogs, the commonest cause of hindlimb lameness in dogs worldwide.
The Cranial Cruciate Ligament runs from the back of the thigh bone (femur) forwards and towards the inside of the knee to insert in the shin bone (Tibia). Essentially it functions to hold the Tibia in a predictable position in relation to the femur.
As you can see on this video, when the Cranial Cruciate Ligament is weak or absent, when the patient loads the limb, the tibia slides forwards. This results in varying degrees of lameness as the leg feels like it is giving way. Lameness is also due to inflammation and swelling within the joint.
In about half of all patients with Cranial Cruciate Ligament pathology, the instability will result in damage to the inner meniscus or cartilage pad between the thigh bone and the shin bone. Damage to this structure generally results in higher levels of lameness and in some patients a catching style of lameness. If you know of someone who has had a "cartilage op" on their knee, this is the structure that they have had removed.
The image shows a typical post operative radiograph taken from the side of the knee. The cage advances the front of the tibia a measured distance based on the pre operative plan. The plate holds the free part of the tibia in position by resisting the pull of the Quadriceps which are the large muscles at the front of the thigh bone. The gap between the front of the tibia and the main body of the tibia fills with bone over a 6-10 week period, permanently changing the shape of the tibia.
Managing Cruciate Disease
As we have identified above, there are two key aspects of Cranial Cruciate Disease that need to be addressed:
- Pathological Instability.
- Deal with any associated meniscal pathology.
In order to assess the integrity of the medial mensicus we will make a small incision into the joint and carefully inspect this structure. If there is damage then we will remove the damaged portion. It is an important structure for the longterm health of the knee but if it is damaged it is just a source of pain and if left, would result in persistent lameness.
Stopping the Tibia sliding forward when the foot is loaded is very important. When this happens it feels like the leg "is giving way" which is an uncomfortable experience. This sliding forwards also makes position awareness difficult to manage as the relative positions of the thigh bone and shin bone are changing rapidly. It is key therefore that we bring this under control.
In the past we had only the option of using materials to try to replicate the function of the original ligament. This was either by using a graft inside the knee or by using a suture to hold the tibia back when the foot is loaded. The problem with these techniques relates to the prolonged period of recovery and the potential for these replacement structures to snap or stretch prematurely, leaving instability as a persistent problem.
More recently it was understood that we could improve the stability of the stifle in the absence of a functional cruciate ligament by changing the shape of the Tibia. This can be done in a number of ways but our preferred method is Tibial Tuberosity Advancement. In this technique we take measurements from radiographs of the knee and establish the appropriate plate size and (very importantly) the cage size required to produce a stable knee in the absence of a functional Cranial Cruciate Ligament.
Post Operative Care
- Weeks 1 and 2: Please restrict activity to house and garden only. Whilst in the garden lead restraint and supervision should be used at all times. It is important to maintain one level living...so no jumping on and off settees or beds. No Stairs.
- Weeks 3 and 4: You can begin lead walking at 5 minutes 3 to 5 times daily. In addition, frequent short periods on lead in the garden are still permitted. It is important to maintain one level living...so no jumping on and off settees or beds.
- Weeks 5 and 6: The lead walks can be extended to 10 minutes up to 4 times daily. Still maintain a non jumping lifestyle in the house. Steps and stairs are fine with care and supervised and no more than once or twice daily.
- Weeks 7-12: The lead walks can be extended to 15 and ultimately 20 minutes three times daily. If two sesssions are used then aim for one of the sessions being 30 minutes long