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Cruciate ligament disease

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Cruciate injury

The cruciate ligaments are a pair of ligaments within the stifle (knee) joint which tightly anchor the femur(thigh bone) to the tibia (shin bone).

Sadly cruciate injuries in dogs are not uncommon. Usually the cranial cruciate ligament tears or is overly stretched leading to the stifle joint becoming unstable. Dogs with a damaged cruciate ligament are typically described as 5/10 lame and stand in a characteristic way with the foot resting on the floor but the leg not actually taking much of the dog’s weight.

This may have been caused by a traumatic injury,usually a twisting force whilst the stifle is flexed(lots of ball throwing and the grab, twist and returnaction associated with it may pre-dispose to this). However, it is more commonly simply through wear and tear over a number of years due to the conformation of the hind limb. Cruciate disease is more common in overweight animals simply because of the increased forces put through the stifle joint.

Options for treatment

It is important to understand that whatever treatment route we go down,whilst we might get close, we are unlikely to return to a point where the legis 100% as good as it was before the injury.

It is also important to be aware that any joint which has been damaged and/or been subjected to surgery is likely to develop arthritis at a faster rate.

The fact that there are multiple options for treatment of cruciate disease should tell you that none of them are perfect – if one was then it would be the treatment. Each treatment option has its own pros and cons.

Loosely speaking, treatment options can be split into 3 broad groups:

  • Non-surgical.
  • Surgeries which mimic the function of the failed cruciate ligament.
  • Surgeries which alter the shape of the tibia (shin bone) to change the way the forces act through the stifle joint – eliminating the need for a cruciate ligament.

Cruciate injury is more commonly seen in certain breeds or types of dogs –this is likely related to the confirmation (shape) of their stifle joint and may also be affected by the conformation of the hip joint.

In our experience terriers, with their bandy legs and over developed thigh muscles are over represented. Cruciate disease is also commonly seen in Labradors and Mastiffs (particularly in our experience Dogue de Bordeaux). Cruciate disease is rare but not unheard of in cats – in cats it is usually following a trauma (fall or road traffic accident).

Where the cruciate ligament fails in one leg, current evidence suggests that there is around a 40% chance of the ligament in the other leg failing within the animal’s lifetime. This needs to be kept in mind when deciding on treatment options – if you have spent your entire budget on the first leg there may not be enough left if the second leg fails.


If there is only a partial tear to the cruciate ligament, if the joint isn't too unstable and if the dog is lightly built, then good enough results may sometimes be achieved through rest, anti-inflammatories, and a change in lifestyle (less running free and an end to ball throwing). 

However in our experience the joint is always likely to be sub optimal and will develop arthritis at an increased rate due to the instability. Long term joint supplements are likely to be of benefit (Glucosamine hydrochloride,Chondroitin sulphate, Omega 3 fatty acids and maybe avocado oils) – we would recommend using a commercial supplement specifically designed for this, as overdose could be harmful. 

Non-surgical, conservative management is obviously the cheapest option but also often the one with the most unsatisfactory results.

Surgeries which mimic the function of the failed cruciate ligament

Both of the techniques pictured above are very similar and use a synthetic fibre or line to mimic the stabilising action of the cruciate ligament.

Smaller dogs do better than larger dogs with this technique. This is also our technique of choice for cats with cruciate disease.

A bone tunnel is drilled in the front of the tibia and a small bone(called the fabella) at the back of the stifle is used as the second anchor point. The line is threaded then tightened and crimped bringing stability back to the joint.

It is not perfect because the line is on the outside of the bones (but under the skin) whereas the original cruciate ligament was in the middle of the joint. It also tends to leave the affected stifle a little tight – some of the full range of motion may be lost.

The benefits are that it is a quicker, cheaper surgery than those that alter the shape of the tibia. They are more invasive than doing nothing; there is a certain amount of soft tissue trauma involved, but the end result should be superior.

The joint is stable from the minute the implant goes in. Post operatively we advise strict rest for 14 days then a slow return to normal over the next couple of months. This is necessary to allow time for the surrounding tissues to heal and strengthen. Over time it is likely that the implant will slacken slightly but it should provide stability for long enough that the structures surrounding the stifle have time to strengthen / tighten and provide greater support.

Surgeries which alter the shape of the tibia (shin bone)

These procedures alter the angle of the top of the tibia in relation to the pull of the thigh muscles through the patellar tendon. If the top of the tibia can be levelled, so that it is perpendicular 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. This ultimately reduces the amount of front to back movement between the tibia (shin bone) and femur (thigh bone) during weight bearing –effectively “stabilising” the joint.

There are two major methods currently being used – TTA (MMP isa variation of this) and TPLO.

These techniques offer a significantly better end result (on average)than lateral suture. They are also longer surgeries requiring more equipment, skill and expensive implants. For this reason they cost considerably more.

TTA (Tibial Tuberosity Advancement)

A straight cut is made in the tibia and the tibial crest (front part)pushed forward. It is prevented from falling back into place by filling the opening with an implant.

The TTA and MMP (Modified Maquet Procedure) are effectively the same surgery although the implants used are different. We are using the MMP technique as there is deemed to be lower risk of implant failure. The MMP wedges come in variety of thicknesses and lengths to suit dogs of varying sizes.

TPLO (Tibial Plateau Levelling Osteotomy)

A circular cut is made in the top of the tibia and the piece of bone rotated and held in place with a plate. The amount of rotation is decided by measurements and angles taken from x-rays of the affected leg.

A special saw is required and initially this is perhaps less stable than the other techniques.

This technique is currently the gold standard offering the best long term outcome. It is also the technique that requires the most training, equipment and level of surgical skill. As a result it is also the most costly technique.

Post operatively both the MMP(TTA) and TPLO both require 1 month of keeping the dog very quiet, followed by another 2 months of keeping the dog fairly quiet (so in total no off lead exercise for 3 months). Follow up radiographs will need to be taken at 1 and 3 months (these are included in our all-inclusive price packages).

Ultimately, the more complicated the surgery, the better the likely final outcome. However, also, the more invasive the surgery, the longer the recovery, the higher the cost, and potentially the more that can go wrong. In most cases where there have been post-op complications the dog has been allowed or managed to do too much too soon. No surgery or anaesthetic is entirely without risk. Please discuss the risks of any surgery carefully with your vet.

A footnote on meniscii

Within the stifle (knee) joint itself are 2 fatty pads that act like shock absorbers between the two bones (tibia and femur). It is not uncommon that these can be torn at the same time as the cruciate fails. In some cases this can cause a secondary problem (as there is loose tissue within the joint) whilst in many other cases it does not present a problem. Other times there may not be a meniscal tear at the time of surgery but one may develop weeks or months later.

Different experts and different implant companies have different views on what should be done and when. Some argue that every stifle joint should be checked and if necessary attended to at the time of cruciate surgery. 

Others argue that in many cases it is unnecessary, creates a larger wound and prolongs the anaesthetic time, and that a second smaller surgery purely to correct the meniscus can be done later if it is deemed to be needed (usually if the dog is not doing as well post operatively as you would expect).
We can see the value of both arguments, but currently we have chosen to go back into the ones that need it at later date, rather than open them all up as a matter of course.

A comparison of options for cruciate injury treatment

Non-surgical Management


  • Cheapest option.
  • No post op care or recovery time.
  • Pain and inflammation can be managed to some degree with medication.


  • Poorest functional outcome.
  • Rapid development of osteoarthritis due to instability.

Lateral Suture


  • Significantly better outcome than doing nothing.
  • Cheapest surgical option.
  • Least invasive of the surgical options.
  • Fastest recovery of the surgical options.
  • Shorter anaesthetic time. Useful if poor anaesthetic candidate.
  • Treatment of choice for cats.
  • Can be good choice for old dogs.


  • Final result likely poorer than MMP or TPLO.
  • Suits smaller dogs better than larger dogs.



  • Better outcome than lateral suture.
  • Good compromise between cost and final outcome.
  • Wide range of implant sizes to suit most dogs.Less risk of operator error as saw cut is guided by gig.


  • More expensive than lateral suture. Higher level of surgical skill and training needed. Use expensive equipment.
  • More invasive than lateral suture.
  • Longer anaesthetic time than lateral suture.
  • Longer recovery than lateral suture.
  • Risk of post operative implant failure if leg is overloaded during recovery.



  • Best outcome.
  • Currently the gold standard treatment.mount of rotation can be tailored to each patient.


  • Most expensive option. Highest level of surgical skill and training needed. Uses most expensive equipment.
  • More invasive than lateral suture.
  • Longer anaesthetic time than lateral suture.
  • Longer recovery than lateral suture.
  • Risk of post operative implant failure if leg is overloaded during recovery.
  • Not suitable for dogs under 10kg
  • Not suitable for dogs over 45kg
  • Not suitable for dogs with bilateral (both legs) cruciate rupture
  • Alder Veterinary Practice
  • 137 Worplesdon Road
  • Guildford
  • Surrey
  • GU2 9XA
  • Telephone: 01483 536036