Cruciate ligament disease

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Cruciate injury

The cruciate ligaments are a pair of ligaments withinthe 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 isoverly stretched leading to the stifle joint becomingunstable. Dogs with a damaged cruciate ligament aretypically described as 5/10 lame and stand in acharacteristic way with the foot resting on the floorbut the leg not actually taking much of the dog’sweight.

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 wearand tear over a number of years due to theconformation of the hindlimb. Cruciate disease ismore common in overweight animals simplybecause of the increased forces put through thestifle 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 damagedand/or been subjected to surgery is likely to develop arthritis at a fasterrate.

The fact that there are multiple options for treatment of cruciate diseaseshould tell you that none of them are perfect – if one was then it would beTHE 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 theway the forces act through the stifle joint – eliminating the need for acruciate 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 mayalso be affected by the conformation of the hip joint.

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

Where the cruciate ligament fails in one leg, current evidence suggests thatthere is around a 40% chance of the ligament in the other leg failing withinthe animal’s lifetime. This needs to be kept in mind when deciding ontreatment options – if you have spent your entire budget on the first legthere 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 toounstable and if the dog is lightly built, then good enough results maysometimes be achieved through rest, anti-inflammatories, and a change inlifestyle (less running free and an end to ball throwing). However in ourexperience the joint is always likely to be sub optimal and will developarthritis at an increased rate due to the instability. Long term jointsupplements are likely to be of benefit (Glucosamine hydrochloride,Chondroitin sulphate, Omega 3 fatty acids and maybe avocado oils) – wewould recommend using a commercial supplement specifically designed forthis, as overdose could be harmful. Non-surgical, conservative managementis obviously the cheapest option but also often the one with the mostunsatisfactory results.

Surgeries which mimic the function of the failed cruciate ligament

Both of the techniques pictured above are very similar and use asynthetic fibre or line to mimic the stabilising action of the cruciateligament.

Smaller dogs do better than larger dogs with this technique. This isalso 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 secondanchor point. The line is threaded then tightened and crimpedbringing stability back to the joint.

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

The benefits are that it is a quicker, cheaper surgery than those thatalter the shape of the tibia. They are more invasive than doingnothing; there is a certain amount of soft tissue trauma involved, butthe end result should be superior.The joint is stable from the minutethe implant goes in. Post operatively we advise strict rest for 14 daysthen a slow return to normal over the next couple of months. This isnecessary to allow time for the surrounding tissues to heal andstrengthen. Over time it is likely that the implant will slacken slightlybut it should provide stability for long enough that the structuressurrounding the stifle have time to strengthen / tighten and providegreater support.

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

These procedures alter the angle of the top of the tibia in relation tothe pull of the thigh muscles through the patellar tendon. If the top ofthe tibia can be levelled, so that it is perpendicular from the pull ofthe patellar ligament, the pull of that ligament during weight bearingwill minimise the forward and back ward shift of the bones. Thisultimately reduces the amount of front to back movement betweenthe 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 moreequipment, skill and expensive implants. For this reason they costconsiderably 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 fillingthe opening with an implant.

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

TPLO (Tibial Plateau Levelling Osteotomy)

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

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

This technique is currently thegold standard offering the bestlong term outcome. It is also thetechnique that requires the mosttraining, equipment and level ofsurgical skill. As a result it is alsothe most costly technique.

Post operatively both the MMP(TTA) and TPLO both require 1month of keeping the dog veryquiet, followed by another 2months of keeping the dog fairlyquiet (so in total no off leadexercise for 3 months). Follow upradiographs will need to be takenat 1 and 3 months (these areincluded in our all-inclusiveprice packages).

Ultimately, the more complicated the surgery, the better the likely final outcome. However, also, the more invasive the surgery, the longer the recovery, thehigher the cost, and potentially the more that can gowrong. In most cases where there have been post-opcomplications the dog has been allowed or managed todo too much too soon. No surgery or anaesthetic isentirely without risk. Please discuss the risks of anysurgery 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 Mangement


  • Cheapest option.
  • No post op care or recovery time.
  • Pain and inflammation can be managed to somedegree 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 anaestheticcandidate.
  • 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 surgicalskill 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 andtraining 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.
  • Alder Veterinary Practice
  • 137 Worplesdon Road
  • Guildford
  • Surrey
  • GU2 9XA
  • Telephone: 01483 536036