Surgery gets bark of ap­proval to fix dog’s knee

Pretoria News Weekend - - NEWS - DR TIM KRAFFT, BVSC

KNEE prob­lems in dogs are seen com­monly by vets, and the most fre­quent rea­son for this is cra­nial cru­ci­ate lig­a­ment (CCL) dis­ease. The knee of the dog is sta­bilised, not specif­i­cally by the shape of the joint, as in ball and socket joints (hip) and hinge joints (el­bow), but re­lies more on lig­a­ments, joint cap­sule and car­ti­lages.

Essen­tially, the knee joint has two rounded ends to the fe­mur that are coated with car­ti­lage that rest on a rel­a­tively flat­tened tib­ial ta­ble. The tib­ial ta­ble has two “C” shaped car­ti­lages called menisci that are de­signed to ac­cept the rounded fe­mur ends (trochlea).

The ma­jor lig­a­ments of the knee in­ter­nally are the cru­ci­ate lig­a­ments, so called be­cause the two lig­a­ments cross over each other, the one lig­a­ment pre­vent­ing for­ward slip of the fe­mur and the other the op­po­site slip.

The knee is fur­ther sta­bilised on the sides by the col­lat­eral lig­a­ments, and fi­nally by the cap­sule. The lig­a­ment that is most of­ten the prob­lem is the cra­nial cru­ci­ate lig­a­ment, known in hu­mans as the an­te­rior cru­ci­ate lig­a­ment (ACL).

In an­i­mals the lig­a­ment may grad­u­ally de­te­ri­o­rate and then sud­denly rup­ture, whereas in hu­mans the rup­ture is nor­mally as­so­ci­ated with a spe­cific se­vere in­jury.

If the lig­a­ment rup­tures sud­denly, there is a dis­cernible loss of use of the leg; ini­tially it will be held in the air, the knee may be swollen and painful but af­ter a few days you will see your dog us­ing the leg a little again, al­beit with a limp.

If you look care­fully you may see some of the other tell-tale signs: “toe touch­ing” or plac­ing of the foot on the tips of the toes with min­i­mal weight bear­ing. A slight twist of the lower leg with the an­kle ro­tated out­wards, and the “sit sign” where the af­fected leg is held straight out when sit­ting.

Di­ag­no­sis is based on a phys­i­cal ex­am­i­na­tion by a vet. Ma­nip­u­la­tion of the knee should re­veal a di­ag­nos­tic loose­ness in the joint which in­di­cates lig­a­ment dam­age. This may have to be done un­der se­da­tion as it can be painful. X-rays are help­ful in aid­ing the di­ag­no­sis and im­por­tant in plan­ning the ther­apy.

What to do about it?

This is a phys­i­cal prob­lem that most of­ten re­quires surgery to pro­vide an ac­cept­able re­cov­ery. The surg­eries that are ef­fec­tive are myr­iad and should be based on the pa­tient’s specifics – size, weight, ac­tiv­ity level and age.

Small pa­tients nor­mally do well with a re­pair that in­volves the use of a lig­a­ment “mimic” placed in a sim­i­lar align­ment to the damaged lig­a­ment, ly­ing just out­side the joint cap­sule. The tis­sues in that area grad­u­ally de­posit scar tis­sue along the line of the pros­thetic lig­a­ment that ul­ti­mately take over the func­tion of the damaged lig­a­ment.

Large (12kg plus) and highly ac­tive dogs ben­e­fit more from surg­eries that ob­vi­ate the need for an in­tact CCL.

It may seem strange that to re­pair a lig­a­ment we ac­tu­ally cut and move bone but it works re­ally well, has been ex­ten­sively re­searched, and gives long-term re­sults. The ac­cepted re­sults achieved by most sur­geons are in the re­gion of 90% of dogs do­ing well af­ter surgery.

Some vari­ances do come into play with dam­age to the car­ti­lage and ex­ist­ing bony changes (os­teoarthri­tis) re­sult­ing in a more neg­a­tive out­come. In all of the cases, phys­io­ther­apy helps speed up and re­sult in op­ti­mal re­cov­ery.

As with any prob­lem there is gen­er­ally more than one way to solve it.

Many other pro­ce­dures have been tried and some are still used in prac­tice, with vary­ing re­sults. Older pro­ce­dures in­clude us­ing thick fi­brous strips from the thigh mus­cle placed through drilled tun­nels in the knee to anatom­i­cally mimic the CCL, to newer patented meth­ods us­ing very strong fi­bres placed through drill holes.

Some vets even in­ject blood into the joint in the hope that the lig­a­ment will heal and

that suf­fi­cient in­ter­nal ir­ri­ta­tion from the blood will cause scar­ring and sta­bil­i­sa­tion of the knee. This

has been re­peat­edly re­futed in lit­er­a­ture but of­fers a cheap al­ter­na­tive to surgery.

Stem cell ther­apy can be used as an ad­junct to surgery to aid in heal­ing and car­ti­lage re­gen­er­a­tion, as can the use of platelet rich plasma.

All in all, surgery seems to be the best op­tion, with very good longterm re­sults and a happy, com­fort­able pet in most cases.

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