How to Perform Ethyl Alcohol Arthrodesis of theTarsometatarsal Joint in the Standing Horse

Chris D. Bell, DVM; David G. Wilson, DVM; Ryan W.E. Wolker, DVM;Luca Panizzi, DMV; Joe L. Bracamonte, DVM; andJames L. Carmalt, MA, VetMB, MVSc

Authors’ address: Department of Large Animal Clinical Sciences, Western College of VeterinaryMedicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Can-ada; e-mail: cdb380@mail.usask.ca. © 2009 AAEP.

1. Introduction

Ethyl alcohol arthrodesis of the tarsometatarsaljoint in the horse is a new technique developed toalleviate the pain associated with osteoarthritis ofthe tarsometatarsal and distal intertarsal joints(bone spavin).1 Ethyl alcohol is administered intothe tarsometatarsal joint to facilitate chemical arth-rodesis of the joint. The mechanism of action of ethylalcohol is through non-selective protein denaturationand cell protoplasm precipitation and dehydration.1

Ethyl alcohol also functions as a neurolytic agent thatresults in a sensory innervation blockade at the intra-articular level. The neurolytic and non-selective pro-tein-destructive properties contribute to its success atdisrupting the cartilaginous matrix, causing necrosisof the chondrocytes, and hastening arthrodesis.1

Ethyl alcohol is inexpensive and readily available tomost practitioners.

Osteoarthritis of the small tarsal joints is one ofthe leading causes of hindlimb lameness in the per-formance horse.2 Several options are available totreat horses with osteoarthritis of the tarsometatar-sal and distal intertarsal joints; they include sys-temic non-steroidal anti-inflammatory drugs and

intra-articular corticosteroids.3 This medical man-agement option is often combined with adjunctivetreatments such as systemic or intra-articular hyal-uronate4 and oral administration of glucosamine.5

More recently, avocado and soybean unsaponifiableextracts6 have been suggested as disease-modifyingagents in induced osteoarthritis of thecarpus. Other options that allow the horse to re-turn to pain-free function aim to fuse the jointsinvolved. Fusion or arthrodesis can be achieved bychemical destruction of the cartilage or intra-articular drilling of the space to destroy the cartilagesurfaces.7 Laser-assisted arthrodesis has also beensuggested as an option to fuse the tarsometatarsaland distal intertarsal joints.8 Both surgical optionsrequire prolonged convalescence, and they increasemorbidity and expense.1,7 Monoiodoacetate (MIA)is a chemical means of causing articular cartilagedestruction by inhibiting chondrocyte metabolism toproduce chondrocyte death.9,10 The mechanism ofaction of MIA is through chondrocyte death followedby mechanical breakdown of the articular cartilageover time. After the cartilage is destroyed, arthro-desis occurs through the healing of the adjacent

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NOTES

subchondral bone plates. Unfortunately, MIA is aparticularly noxious chemical within the joint, and itcauses severe discomfort for the horse after treat-ment, progression of osteoarthritis within the prox-imal intertarsal joint, severe soft tissue reaction ifthe chemical is injected into the extra-articularspace, and inconsistent outcomes.9,10

Ethyl alcohol fulfills a number of conditions thatmake it optimal for use as an alternative to thetraditional method for arthrodesis of the tarsometa-tarsal joint. Ethyl alcohol is minimally invasivecompared with current accepted treatments, and itresults in effective destruction of the articular car-tilage and cartilaginous matrix, which leads to ar-throdesis in as little as 4 mo.1 Horses experienceminimal to no appreciable discomfort throughoutthe treatment period, there are no adverse reactionsif inadvertently administered extra-articularly, it isaffordable, and it has minimal side effects.1

2. Materials and Methods

Equipment

The equipment needed includes a 1.5-in, 20- or 19-gauge needle, sterile, injectable radio-opaque con-trast material, 70% ethyl alcohol, an intermittantinfusion pluga (PRN) injection port, and syringe.For radiographs, a standard film or digital proces-sor/reader and portable X-ray generator will berequired.

Restraint

Most horses will tolerate injection of the tarsometa-tarsal joint if adequately sedated. Additional re-straint may not be necessary.

Technique: Tarsometatarsal (TMT) Joint

Before injection of alcohol, the horse must undergo afull lameness exam, and the tarsometatarsal jointshould be blocked with intra-articular anesthetic toprove that the lameness originates from the tarso-metatarsal joint. After localization of the lame-ness, the plantar-lateral aspect of the tarsus isclipped and aseptically prepared. The head of thelateral splint bone is sterilely palpated, and a 1.5-in,20- or 19- gauge needle is inserted into the jointdistally and dorsomedially over the head of the lat-eral splint bone until it is seated within the tarso-metatarsal joint. Sterile radio-opaque contrastmedium (�3 ml) is sterilely injected into the tarso-metatarsal joint. The syringe is removed, and aPRN injection port is affixed to the needle and left inthe joint. Radiographs are taken immediately afterinjection of the contrast and application of the injec-tion port. If no communication is identified be-tween the tarsometatarsal and proximal intertarsalor tibiotarsal joints, an empty sterile syringe is at-tached to the injection port and aspirated to removeexcess contrast within the joint. Approximately 3ml of 70% ethyl alcohol is injected through the in-jection port into the tarsometatarsal joint. The

needle with the injection port is removed from thejoint, and the region is covered with sterile bandageapplied with an adhesive wrap. The horse is givena single dose of phenylbutazoneb (2.2 mg/kg, IV orPO). The bandage is removed the following day.A similar technique can be employed for the distalintertarsal joint from the medial approach.

Radiographic Evaluation of Contrast ArthrographyThe radiographs should be examined to ensure thatthere is no communication of the tarsometatarsaljoint with the distal intertarsal, proximal intertar-sal, or tibiotarsal joints. The radiographic seriesneeds to include a straight lateral to medial viewand dorsal to plantar view. In an acceptable ar-throgram of the tarsometatarsal joint, a contrastline will be evident within only the tarsometatarsaljoint space (Fig. 1). If the contrast line extends intoand fills part of the proximal intertarsal or tibiotar-sal joints (Fig. 2), alcohol injection must be aborted,and this horse is not a candidate for alcohol fusion ofthe tarsometatarsal joint. If communication existsbetween the tarsometatarsal and distal intertarsaljoint, it is prudent to complete a contrast arthro-gram of the distal intertarsal joint to ensure com-

Fig. 1. Contrast arthrogram of the tarsometatarsal joint in ahorse with naturally occurring osteoarthritis. Intra-articularcontrast is only within the tarsometatarsal joint on this dorso-plantar view. No communication is evident between the tarso-metatarsal joint and the proximal joints. Alcohol injection isindicated.

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munication does not occur with the two proximaljoints.

3. Results

Sixteen horses are currently enrolled in a prospec-tive study examining the efficacy of ethyl alcohol.In all treated horses, the tarsometatarsal joint wassuccessfully injected. To date, the technique hassuccessful resolved lameness in all 16 horses evalu-ated at the radiographic recheck exam 6–12 moafter alcohol injection. All horses that have re-turned for follow-up evaluation have had radio-graphic evidence of tarsometatarsal joint ankylosisat 4–6 mo and are pain free. Four horses that havecompleted the study beyond 12 mo are sound andreturned to intended use. There have been no det-rimental extra-articular alcohol reactions in any ofthe horses evaluated. One horse developed mildsoft tissue swelling around the head of the fourthmetatarsal bone that resolved within 24 h. Fourhorses have required general anesthesia to performcontrast arthrogram and alcohol injection after un-successful attempts to perform the procedure stand-ing. In these horses, the distal intertarsal jointwas also evaluated with contrast arthrography and

injected with alcohol if no communication with theproximal joint was appreciated.

4. Discussion

The technique for ethyl alcohol arthrodesis of thetarsometatarsal joint can be completed with relativeease and little time provided radiographic equip-ment and processing is readily available. Digitalradiography makes this technique applicable to in-hospital and field application. Because the tech-nique is no more challenging than tarsometatarsaljoint injection, the general equine practitionershould have little difficulty integrating this methodinto regular use for selected cases. Case selectionshould be limited to those horses that are refractoryto traditional treatment such as corticosteroids, andselection should also be limited to horses with ad-vanced osteoarthritis of the small tarsal joints.Young horses with osteoarthritis should be ap-proached by traditional modalities initially beforeimplementing the use of ethyl alcohol-facilitated an-kylosis. Horses tolerate the technique well withsedation. In the horses treated in this manner thathave clinical osteoarthritis of the tarsometatarsaljoint, there have been few complications. The mostcommon complication has been ensuring accurateaccess to the tarsometatarsal joint in horses withadvanced osteoarthritis. Typically, needle place-ment into the joint has been confirmed by presenceof synovial fluid within the hub of the needle and/orradiographic examination. If this confirmation wasnot available, ease of contrast delivery into the nee-dle has been used to assess proper placement withinthe joint.

The other most common difficulty encountered isassessment of the contrast arthrogram. There areseveral confounding factors with assessment of thecontrast arthrogram of the tarsometatarsal joint.In multiple cases, contrast can be seen within thegreater tarsometatarsal or peroneal artery and/orvein on the arthrogram. This should be carefullyevaluated but not interpreted as communication be-tween the tarsometatarsal joint and the proximaljoints. Another confounding factor is extra-articu-lar injection of contrast. This will appear as a dif-fuse opacity of contrast over the plantar-lateralaspect of the tarsus at the head of the lateral fourmetatarsal bone. This should not be interpreted ascommunication between the tarsometatarsal jointand proximal tarsal joints (Fig. 3). The final diffi-culty in assessing arthrograms is obliquity of theradiograph. Straight, level views are required toproperly and confidently confirm contrast mediumwithin the articular space of the tarsometatarsaljoint. These difficulties are easily overcome withthorough attention to proper technique and a mod-erate level of radiographic interpretation skills.Practitioners will find that they quickly become com-fortable with radiographic evaluation after only afew horses.

Fig. 2. Contrast arthrogram of the distal intertarsal joint in ahorse with naturally occurring osteoarthritis. Intra-articularcontrast is evident within the proximal intertarsal and tibiotarsaljoints. A communication exists, and this horse is not a candidatefor alcohol arthrodesis of the distal intertarsal joint

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Studies are currently underway to characterizethe efficacy and use of ethyl alcohol in horses withnaturally occurring osteoarthritis of the tarsometa-tarsal and distal intertarsal joints. In a recentstudy by Shoemaker et al.,1 50% of normal horses

were radiographically arthrodesed by 4 mo and 15 of16 (94%) were fused by 12 mo with the use of 70%ethyl alcohol in the tarsometatarsal joint. Currentdata from a prospective clinical trialc has shown that16 of 16 horses with naturally occurring osteoarthri-tis of the tarsometatarsal joint have decreased lame-ness and are sound at 6–12 mo.

References and Footnotes1. Shoemaker RW, Allen AL, Richardson CE, et al. Use of

intra-articular administration of ethyl alcohol for arthrodesisof the tarsometatarsal joint in healthy horses. Am J Vet Res2006;67:850–857.

2. Sullins KE. The tarsus. In: Stashak TS, ed. Adams’lameness in horses, 5th ed. Baltimore: Lippincott, Wil-liams & Wilkins, 2002;930–987.

3. Auer JA. Tarsus. In: Auer JA, Stick JA, eds. Equine sur-gery, 3rd ed. Philadelphia: W.B. Saunders Co., 2005;1288–1307.

4. Gough M, Munroe G. Decision making in the diagnosis andmanagement of bone spavin in horses. In Pract 1998;20:252–258.

5. Clayton HM, Almeida PE, Prades M, et al. Double-blindstudy of the effects of an oral supplement intended to supportjoint health in horses with tarsal degenerative joint disease,in Proceedings. 48th Annual American Association ofEquine Practitioners Convention 2002;314–317.

6. Kawcak CE, Frisbie DD, McIlwraith CW, et al. Evaluationof avocado and soybean unsaponifiable extracts for the treat-ment of horses with experimentally induced osteoarthritis.Am J Vet Res 2007;68:598–604.

7. Wyn-Jones G, May SA. Surgical arthrodesis for treatmentof osteoarthrosis of the proximal intertarsal, distal intertar-sal and tarsometatarsal joints in 30 horses: a comparison offour different techniques. Equine Vet J 1986;18:59–64.

8. Hague BA, Guccione A. Laser-facilitated arthrodesis of thedistal tarsal joints. Clin Tech Equine Pract 2002;1:32–35.

9. Bohanon TC, Schneider RK, Weisbrode SE. Fusion of thedistal intertarsal and tarsometatarsal joints in the horseusing intra-articular monoiodoacetate. Equine Vet J 1991;23:289–295.

10. Dowling BA, Matthews SM. Chemical arthrodesis of the distaltarsal joints using monoiodoacetate in 104 horses. Aust Vet J2004;82:38–42.

aIntermittant infusion plug, Kendall Argyle, Tyco HealthcareGroup, Mansfield, MA 02424.

bIVX Animal Health, Inc., St. Joseph, MO 64506.cCarmalt JL. Personal communication, 2009.

Fig. 3. Contrast arthrogram of the tarsometatarsal joint in ahorse with naturally occurring osteoarthritis. Intra-articularcontrast is only within the tarsometatarsal joint. No communi-cation is evident between the tarsometatarsal joint and the prox-imal joints. There is extravasation of the contrast medium intothe subcutaneous tissue over the head of the lateral splint bone.This should not be considered communication with any of theproximal joints, and it is a common complication in performingcontrast arthrography.

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