Health

What you need to know about up­ward fix­a­tion of the patella

Dressage Today - - Content - By Justin Sob­ota, MS, MSM, DVM

Sticky Sti­fle Man­age­ment

Does your horse have that no­to­ri­ous “sticky” sti­fle? Did your trainer say that your horse “just isn't right” or has a “hitch in his giddy-up?” We may have heard th­ese state­ments, but what may be truly oc­cur­ring is an up­ward fix­a­tion of the patella (UFP).

The patella is lo­cated in the sti­fle at the in­ter­sec­tion of the fe­mur and tibia. The patella rests on the me­dial trochlear ridge of the fe­mur, which is im­por­tant for the pas­sive stay ap­pa­ra­tus. This unique fea­ture al­lows the horse to rest stand­ing with min­i­mal ef­fort. A prob­lem oc­curs when the patella does not dis­en­gage prop­erly from the me­dial trochlear ridge and the leg ap­pears “stuck” or “sticky” and the limb may even re­main in ex­ten­sion.

We have seen mild to se­vere UFP in dres­sage horses. Mild UFP has jerky move­ments due to a de­layed re­lease of the patella. Se­vere UFP can be seen as an ex­ten­sion of the limb be­hind the horse be­cause of a locked patella.

The pre­cise cause of UFP is not com­pletely known. One study sug­gests that it is the spas­modic or tonic ac­tiv­ity of the vas­tus me­di­alis of the quadri­ceps femoris mus­cle. We do know that the risk fac­tors for UFP can in­clude poor con­for­ma­tion, poor con­di­tion­ing, ge­net­ics and poor foot con­for­ma­tion (high me­dial hoof-wall height and long toes). The con­di­tion is most com­monly iden­ti­fied in young, un­trained horses and adult horses who may be out of work and los­ing mus­cle rapidly. Surgery to cor­rect the prob­lem is most com­mon in warm­bloods (31.8 per­cent) fol­lowed by Stan­dard­breds (18 per­cent), Ara­bi­ans (11.8 per­cent), Ice­landics (9.4 per­cent), Thor­ough­breds (7 per­cent), ponies (8.3 per­cent) and Friesians (4.7 per­cent). The same study iden­ti­fied a me­dian age of 7 years and the most com­mon dis­ci­plines were plea­sure (48.2 per­cent) fol­lowed by dres­sage (17.6 per­cent).

UFP may oc­cur as a uni­lat­eral or bi­lat­eral hind-limb con­di­tion and can be ei­ther in­ter­mit­tent or per­ma­nent in na­ture. Con­ser­va­tive and sur­gi­cal treat­ments have been stud­ied and ap­plied to horses. It is al­ways im­por­tant to have a proper di­ag­no­sis from your vet­eri­nar­ian prior to in­sti­tut­ing any ther­apy.

Con­ser­va­tive treat­ment usu­ally is in­sti­tuted if the con­di­tion is not cre­at­ing a lame­ness and is in­ter­mit­tent. Treat­ments in­clude cor­rec­tive trim­ming and shoe­ing, con­di­tion­ing, chi­ro­prac­tic, acupunc­ture/ aqua punc­ture, pro lo ther­apy, phar­ma­ceu­ti­cal in­ter­ven­tion( an­abolic steroids andc hon dro pro­tec­tives) and io dine-con­tain­ing coun­terir­ri­tants. Con­di­tion­ing can in­clude hill work both di­ag­o­nally and per­pen­dic­u­lar in di­rec­tion. Cor­rec­tive trim­ming and shoe­ing may in­volve short­en­ing the toe to im­prove a neg­a­tive plan­tar an­gle, cor­rect­ing me­dial-lat­eral bal­ance, el­e­vat­ing the lat­eral heel and round­ing the me­dial toe. Phar­ma­ceu­ti­cals are es­tro­gen com­pounds (hor­monal ther­apy) given in the mus­cle and can the­o­ret­i­cally in­crease the ten­sion of the sup­port­ing soft-tis­sue struc­tures help­ing to change the po­si­tion of the patella.

As a vet­eri­nar­ian, I will gen­er­ally start with a com­bi­na­tion of con­ser­va­tive treat- ments, es­pe­cially in a young horse prior to mat­u­ra­tion. If the con­ser­va­tive treat­ment is not pro­vid­ing the de­sired suc­cess, sur­gi­cal op­tions can also be pro­vided.

Sur­gi­cal treat­ment in­cludes a min­i­mally in­va­sive sur­gi­cal pro­ce­dure called me­dial patel­lar lig­a­ment split­ting/fen­es­tra­tion, which can be com­pleted in a stand­ing po­si­tion. A more in­va­sive surgery is the me­dial patel­lar lig­a­ment desmo­tomy, which is typ­i­cally com­pleted un­der gen­eral anes­the­sia. In ei­ther case, a two-week re­ha­bil­i­ta­tion may be needed for im­prove­ment or res­o­lu­tion af­ter surgery.

A re­cent ret­ro­spec­tive study found that surgery (re­cum­bent or stand­ing) pro­vided a 97.6 per­cent com­plete res­o­lu­tion ei­ther im­me­di­ately or af­ter up to two weeks of re­ha­bil­i­ta­tion. No short- or long-term com­pli­ca­tions were re­ported.

Up­ward fix­a­tion of the patella can be a con­cern in your dres­sage horse, but know that a myr­iad of con­ser­va­tive and ul­ti­mately sur­gi­cal op­tions can be pro­vided with good suc­cess. Many suc­cess­ful dres­sage horses have over­come UFP.

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