Key to the functioning of the stifle are the ligaments. The big ones on the inside and outside are called the collateral ligaments and stop the stifle hinging to the side. The pair of cruciate ligaments are arranged in a crossed over pattern (crucifix). Their job is to prevent forward and backwards movement in the tibia in the direction of the arrows. This means as the stifle flexes and extends the surfaces glide over each other and a healthy stifle will flex and extend millions of times in a lifetime, without wearing out. It is the cranial or anterior cruciate which is the most commonly injured and whose job is to stop the tibia sliding forward in relation to the femur.
The final significant part of the anatomy of the stifle is the meniscii or “cartilages”. There are two in each stifle, both kidney bean shaped and lying to the inside and outside of the middle axis of the joint. They act as a shock absorber and also help restrict the forward and back movement of the tibia but are only able to do this in combination with the cruciate.
Why do cruciate ligaments fail?
We see many presentations of cruciate failure but broadly speaking they can be truly traumatic where an extreme of force is applied to a relatively normal ligament. Such an event might include a road accident, or jumping for a Frisbee, or running along and putting the foot down a hole or jumping a fence and getting a foot caught.
Other patients we see have a degenerating cruciate that finally fails when subjected to modest or even normal stresses. This can happen to both older dogs but also younger dogs, the younger ones often having poor hips as well. Unfortunately dogs with degenerating cruciates often end up with both stifles affected.
What will I see?
In the truly traumatic cases, your cat or dog will be usually completely lame and obviously sore.
With the degenerative ones the dogs (as it tends to be dogs who present in this way) are lame but the lameness can be variable from complete to light.
How is it diagnosed?
A thorough examination and history taking will often establish that the problem lies within the stifle. Being able to feel or see the abnormal forward and back movement of the tibia would confirm the diagnosis.
However often the injury is quite subtle and sometimes only a partial tear is present. Also sometimes dogs are so tense that it is impossible to demonstrate the abnormal movement.
The next stage is to repeat the examination under sedation and also take some x-rays. This means the limb is relaxed and often the abnormal movement can be generated whereas it was not felt in the consulting room. Some dogs have such a small tear that no abnormal movement can be produced but they are, unfortunately on a journey towards failure.
Although ligaments are not seen in an x-ray, the picture can show up early signs of change in the joint such as extra fluid in the joint or the appearance of little spicules of new bone.
What is the consequence of cruciate failure?
Once the cruciate is damaged enough to allow abnormal movement in the joint the joint starts along a journey of arthritis. The journey is unfortunately only one way and the joint will continue to deteriorate throughout the animal’s life. However there is much that can be done to reduce the severity of the arthritis and therefore the impact of the injury
What should be done?
Some cats and very small (toy) dogs will, sometimes, do well enough, given several weeks of cage rest. This is a strict regime, not to be undertaken lightly. The pet is confined in a cage at home and in the case of a dog lifted outside for toileting and then lifted back into the cage. The idea of this treatment is that the other structure in the joint will “beef up” to allow the joint to function without the cruciate ligament. Results tend to be variable but it can provide an economical outcome, in some cases.
Small and medium patients can be treated by a surgical stabilisation of the joint. There have been many dozen techniques described in the literature over the years. At Oak Tree Vet Centre, a fascial graft is the method used.
Larger dogs, Labradors and above can do well with a fascial graft but their recovery is slower and the graft is vulnerable to snapping. For these patients an Orthofoam MMP TTA, (Modified Maquet Procedure using an Orthofoam implant to create a Tibial Tuberosity Advancement) is performed, in preference.
Fascial graft repair.
A fascial graft or “over the top” repair is a soft tissue repair where a strip of the dog’s (or cat’s) own tissue is harvested from the fibrous tissue covering the muscle of the thigh and placed within the joint to mimic the path and function of the failed ligament.
A long incision is made along the outside front centre line of the leg and a strip of fibrous tissue detached from the top of the leg, near the hip and carefully peeled down the leg to where the patellar (kneecap) ligament goes into the tibia. The stifle joint is then opened and the torn ligament remnants cut away using a fine blade to allow the graft to be passed. Then, the cartilages are carefully inspected for damage and any damaged portions removed.
The graft is passed between the condyles (knuckles) of the femur and round the back of and over the top of the outside of two little bones called fabellae. The graft is then sutured down to the outside of the femur and the end taken down and sutured to its starting point for a more robust repair.
The joint is then flushed of clots and debris with sterile saline and then flushed with local anaesthetic which promotes a more comfortable recovery.
The joint and the fascia is then closed. The harvesting of the graft means that after closing the gap the fascia is pulled tight. This adds to the stabilisation of the joint provided by the graft.
The remaining tissues are sutured, routinely.
Bone altering procedures
In large dogs, the speed of recovery and the reliability of the soft tissue repairs is more of a concern due to the larger forces operating in the joint and also on occasions due to anatomical irregularities. In recent years three procedures have evolved, all of which alter the angle of the top of the tibia in relation to the pull of the thigh muscles through the patellar tendon.
With no functioning cranial cruciate ligament, the tibia tends to slide forward and the femur back on each other in the direction of the arrows when the dog bears weight. This accelerates the wear on the joint and the arthritis progresses.
What can be done?
If the top of the tibia or tibial plateau, as it is called, can be levelled, so that it is perpendicular (at 90 degrees) from the pull of the patellar ligament the pull of that ligament during weight bearing will minimise the forward and back ward shift of the bones.
How is this achieved?
Currently there are three main methods
The first and most common is the TPLO or Tibial Plateau Levelling Osteotomy, (osteotomy means cutting of a bone). In this technique, a circular cut is made in the top of the tibia and the little piece of bone rotated and held in place with a plate. A special saw and blade is required for this technique and the repair is perhaps initially less stable with a loose circular section. Also the circular blade may have a tendency to become hotter than a straight blade, risking burning the cut surfaces of the bone and delaying the healing.
The alternative way of altering the angle is to alter the angle of the patellar ligament. This is called a TTA or Tibial Tuberosity Advancement, method. Here a straight cut is made in the tibia and the front section (darker) pushed forward. In the original canine method, the new position was held in place by a sophisticated and expensive titanium plate which can be a vulnerable to catastrophic failure.
A third method is to do a bit of both and a veterinary surgeon in New Zealand, Warrick Bruce, came up with a combination of the two techniques involving straight cuts (less heat) and doing a little bit of both angle changing methods. The method is called the TTO or Triple Tibial Osteotomy. They have developed a special set of instruments to be used alongside the standard orthopaedic saw to remove much of the guesswork and feel needed to manage, successfully, the TTO procedure. It involved making a cut as in the TTA above and then removing a little wedge in the main bone shaft. Closing the wedge drops the front of the tibial plateau like the TPLO and at the same time pushes the tuberosity forward like the TTA. None of the cuts are completely through the bone and when the plate is applied it holds together a straight and inherently stable join.
At Oak Tree Vet Centre, we were offering the TTO as our preferred method of cruciate repair. in large dogs. All of the techniques above involve a similar inspection, removal of cruciate ligament debris and attention to the meniscus.
These bone altering procedures involve a significant investment in training and equipment. Here is our operating trolley, ready to start a TTO.
What do we do now?
The Orthofoam MMP TTA
A new material has recently come into veterinary use. It is a titanium sponge called Orthofoam that allows bone to grow into it creating a secure and permanent bond with the bone.
Cut into precisely measured wedges it is the ideal companion for the TTA procedure filling the wedge, completely and providing a very strong resistance to the wedge space collapsing. It is held in with a single pin and a special titanium orthopaedic staple. In recognition of the first human surgeon Dr. Maquet who first provided a similar procedure for his patients in the 70’s the procedure is the Orthofoam MMP TTA (Modified Maquet Procedure Tibial Tuberosity Advancement.
Orthofoam MMP TTA
What happens on the day of the operation.
Whether your pet is having a fascial graft or Orthofoam MMP TTA, he or she would be admitted early in the morning and settled into one of our day kennels in the prep room.
Prior to the administration of the anaesthetic, we shall weigh and re-examine your pet and if it has not been done already, take a pre anaesthetic blood sample. The practice has a modern blood analyser for this purpose and results are available within 15 minutes, allowing any adjustments to be made in the anaesthetic protocol.
As both procedures are significant operations we provide intravenous fluid support (a drip) for all our cruciate patients.
It is the routine at Oak Tree Vet Centre that patients receive not only a sedative to allay any fear but two analgesics (painkillers) as their premedication before general anaesthesia.
Following induction of anaesthesia, all patients are intubated to protect their airway and maintained via a modern gas anaesthetic system featuring sevoflurane, the latest and considered the best anaesthetic gas. At this time an intravenous antibiotic is given to reduce the risk of infection.
All anaesthetised patients are monitored throughout, by the theatre nurse under the constant supervision of the operating surgeon. The leg is shaved and vacuumed to remove all hair. The skin is then washed and disinfected by a three stage cleansing program
All patients have, of course, their own set of operating drapes and instruments. We have surgical power tools from human surgery that are autoclaved along with the large selection of instruments that are needed for these procedures.
The patient is draped with large cloths and the foot recovered in a sterile bandage.
The procedure begins with both the primary veterinary surgeon and a scrubbed assistant, whilst a veterinary nurse monitors the anaesthetic and a fourth person is available to meet the surgeon’s equipment needs throughout the operation.
At the end of the procedure, before leaving the theatre, the wound is cleansed with sterile saline, dried and a spray bandage applied. On top of this a sterile bandage like a giant elastoplast is stuck.
We don’t use a bandage so that the patient has mobility right from immediately post op.
For dogs undergoing an Orthofoam MMP TTA, a post op x-ray is done to check that the Orthofoam wedge, pins and staple is still correctly placed.
All patients receive post operative pain relief for as long as is required for them to recover from surgery.
We now offer therapeutic laser therapy at the time of surgery to reduce post operative discomfort and swelling. We are the first in Scotland and one of the first few practices, in the UK to have a Class IV laser.
Post operative care
On collecting your pet, both the surgeon and a veterinary nurse will go through what has been found and done and give you written instruction to help you manage the initial recovery.
We like to check all of our cruciate patients after three days. With both methods, we remove the stitches after 10 days.
With the fascial graft, it is imperative that the stifle is carefully cared for with minimal movement; toilet exercise on a lead and no jumping, stairs or playing for the first four weeks and then a gradual increase in lead exercise.
With the Orthofoam MMP TTA, your dog is allowed a few minutes lead walking several times a day right from day one, a big advantage for boisterous large breeds. At six weeks post op, we take a check x-ray to ensure everything is correct.
At this time, we hope to start active rehabilitation. We believe, in the case of medium and larger dogs, the best rehabilitation is hydrotherapy and the equipment of choice is the water treadmill. Twice a week sessions, wading slowly in deep warm water builds up the muscles in the leg, with minimal danger to the healing joint. Our sister business petphysio.co.uk, which is on site, conducts the hydrotherapy, ideally twice a week for 6 weeks (12 sessions).
Prior to, or simultaneous with the hydrotherapy sessions we often give a course of four, once a week, injections of a drug designed to curb the inflammation in the healing joint.
Some of our cruciate patients have continued to attend regularly for hydrotherapy, as the dogs have enjoyed themselves so much and to keep them in peak physical condition.
What about the arthritis?
Unfortunately, the moment the cruciate begins to fail in the case of degeneration or snaps in the case of trauma there is an inflammatory process leading to the establishment of arthritis. Arthritis is a progressive disorder but there are many things that can and should be done to slow down the progression of the arthritis and minimise its impact of your pet’s quality of life. The surgery is a significant part but there are four cornerstones to managing the stifle arthritis or indeed any arthritis.
1) Weight control. Being too heavy does not cause arthritis but if your dog is too heavy and has arthritis or an injury it progresses much more quickly, the disability is then magnified leading to the possibility of failure in another leg.
2) Regular and reasonable exercise. Too much or strenuous activity is just as bad as not enough. If your dog has arthritis you need to look at your pet’s routine, curb the excesses and make time for some gentle exercise every day. Do not fall into the “weekend warrior” where your dog bags some Munroes at the weekend and is wiped out for most of the week, recovering just in time to give his joints another battering the next weekend.
3) Supplements, in the form of additions to normal diet or the shift to a “joint” diet is a major part of looking after the joints, next week, next month and next year.
4) Drugs, surprising, are the last item, not the first. There is undoubtedly a role for drugs to manage the stiffness and inflammation especially early on after surgery or when there is a flare up. However, there may be long periods when daily administration of drugs is not necessary.
At Oak Tree Vet Centre, we are well placed to guide you though making the most appropriate choices for your pet.
Why come to Oak Tree Vet Centre?
Alistair Marks, the proprietor of Oak Tree Vet Centre, is not a registered specialist but is a practitioner of more than 33 years’ experience and has studied for and gained two formal post graduate certificates, one in small animal orthopaedics, the other in veterinary radiology, as well as attending numerous educational meetings both in the UK and abroad. He has brought together what he feels is a worthwhile and comprehensive total case service from diagnosis to managing your pet through the surgery, rehabilitation and then maintaining mobility as far as and as long as possible, all here at the practice. He is ably assisted by a team of six Registered Veterinary Nurses who are very active in the provision of care, at all stages. We are careful to provide the best experience during the perioperative period for your pet and enthusiastic assistance during rehabilitation, which most dogs thoroughly enjoy.
We are content to make a direct claim to most of the significant insurance companies if we have sight of the original policy documents prior to the commencement of treatment. Please read our practice brochure and speak to us to learn more about this aspect of our service.
Referral to Oak Tree Vet Centre
Whilst many of our Orthofoam TTA cases are drawn from our own clients’ pets, we are accepting more and more referral cases, as few surgeries have set themselves up for this procedure.
Whilst we can give you general information about the procedure in the typical patient, your own vet must be the one that decides with you, a referral is the preferred treatment route for your pet. He or she will have decided that your dog is sufficiently healthy to undergo this procedure, from clinical examination and usually by the taking of a general blood test profile.
By the time referral for surgery is decided, most dogs have also had radiographs taken. If these radiographs are suitable for assessment, then we can perform surgery based upon them. If not then we have to take our own image on the day at a cost, in 2017, of £75
Among the required radiograph is a perfect, or close to perfect lateral (side to side) view of the stifle (knee) including the whole of the tibia (shin bone). The centre point of the beam should be just below the tibial joint surface and the stifle in a natural position of about 135 degrees. As a result, the femoral condyles should be overlapping or close to overlapping. There must be a right or left marker and a scaling device.
If your vet has digital radiography, he or she can provide a disc with the images as jpegs and dicoms, which we can use. If the practice is using films then you will be given the originals to bring which will be returned with you.
The cost of the procedure in 2017 is £1695 including VAT and covers all the aspects of the surgical procedure on the day, including post operative x-rays. Dogs over 50kg may need a second titanium staple at an extra cost of £75. In addition to the surgery charge, you might need to purchase enough antibiotics and pain medication to get you to the first post op check at 3 days. We are very happy to liaise with your vet so you can be supplied some or all of your anticipated medicines, by your usual practice, in anticipation of the surgery.
We’ll give you written instruction as to what to do post op.
We like to check the wound at three days and again at ten days when the stitches are removed. It is important that the stitches are not chewed and your vet or we can sell you a plastic cone, if required.
We ask your vet to take a pair of radiographs four weeks after the surgery, under sedation, to check all is well before increasing activity and starting more active rehabilitation, such as water treadmill work. We can do this for your vet, if desired, at a cost in 2017 of £160.