how to inject the tarsal joints · 2018-02-13 · pable anatomic landmark for needle placement is...

How to Inject the Tarsal Joints

John Schumacher, DVM, MS, Diplomate ACVIM*; and Ray Wilhite, PhD

Authors’ addresses: Equine Sports Medicine Program (Schumacher) and Department of Anatomyand Physiology (Wilhite), College of Veterinary Medicine, Auburn University, Auburn, AL 36849;e-mail: [email protected]. *Corresponding and presenting author. © 2012 AAEP.

1. Introduction

The tarsocrural (tibiotarsal), talocalcaneocentral(proximal intertarsal), centrodistal (distal intertar-sal), and tarsometatarsal joints are the four majorjoints that compose the hock. (Incorrect but com-monly used anatomic names are shown in parenthe-ses.1) Because the hock is a common site of pain,arthrocentesis of these joints is commonly per-formed for diagnosis and treatment of lameness.Because the tarsocrural joint (for which arthrocen-tesis is easily accomplished) communicates directlywith the talocalcaneocentral joint, the talocalcaneo-central joint is rarely approached. How commonlythe centrodistal (CD) joint communicates directlywith the tarsometatarsal (TMT) joint is controver-sial. Studies report that these two joints occasion-ally communicate directly (ie, anatomically), but thereported frequency of direct communication variesfrom 8.3% to 35%.2–7 Using hocks from cadaversand injecting latex into the TMT joint, Sack andOrsini found direct communication between theTMT and CD joints in 8.3% of hocks when latex wasinjected until resistance was felt and in 23.8% ofhocks when injection was continued until resistancewas overcome.2 Brown and Valko injected methyl-ene blue into the TMT joint of 34 postmortem spec-imens and found direct communication with the CDjoint in 8.8% of the specimens.7 Investigators in

another study found direct communication betweenthe two joints in 31% of cadaver limbs but found nocorrelation between pressure of injection of ra-diopaque contrast solution and the incidence of com-munication.3 An in vivo study reported diffusion ofdiluted latex from the TMT joint to the CD joint in26% of hocks.4 In another in vivo study, in whichpositive radiographic contrast agent was injectedinto both TMT joints of 10 horses, direct communi-cation between the TMT and CD joints was observedradiographically in 35% of limbs.5

Functional communication of the TMT and CDjoints was demonstrated by Gough et al, who found,using cadaver limbs, that a therapeutic concentra-tion of mepivacaine HCl diffused from one joint toanother, even when the joints did not communicatedirectly.8 Functional communication of the TMTand CD joints was also found by Serena et al, whofound in an in vivo study a therapeutic concentra-tion of methylprednisolone acetate in the CD joint ofhorses soon after administration of the drug into theTMT joint.9 Because direct communication be-tween the TMT and CD joints is inconsistent, clini-cians often inject each joint either with localanesthetic solution to diagnose pain in the distaljoints of the hock as a cause of lameness or with acorticosteroid to treat horses affected with osteoar-thritis of the distal tarsal joints. Other clinicians,

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HOW TO MAKE RATIONAL CHOICES FOR INTRA-ARTICULAR INJECTIONS

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however, do not inject the CD joint and rely ondiffusion of local anesthetic solution or corticosteroidinto it from the TMT.9–14

2. Materials and Methods

A lip-twitch usually provides adequate restraint forarthrocentesis of the tarsal joints. The joints areusually entered with the limb bearing weight, but toincrease safety of arthrocentesis of the TMT jointwhen dealing with horses likely to kick, the joint canbe entered with the limb extended caudally.9 Withthe limb held, the technique for arthrocentesis is thesame. When working with poorly behaved horses,sedation or tranquilization may make the proceduresafer, but before diagnostic analgesia is performed,the authors prefer to observe the effect that sedationor tranquilization has on the horse’s gait.

Arthrocentesis of the TMT JointThe most commonly used technique for arthrocente-sis of the tarsometatarsal joint is a plantarolateralapproach reported by Brown and Valko.7 The pal-pable anatomic landmark for needle placement isthe head of the fourth metatarsal bone. A 20- or21-gauge needle is inserted about 0.25 inch (0.6 cm)above the head of the lateral splint bone and 0.5-inch (1.3 cm) lateral to the lateral edge of the super-ficial digital flexor tendon. Most authors advisedirecting the needle slightly downward, toward thedorsomedial aspect of the hock (Fig. 1), but, whenaiming the needle in this manner, Brown and Valkofound a 10% incidence of failure7 and Dyson andRomero experienced a 5% rate of failure.5 Sack andOrsini, in a large study using cadaver limbs, had anincidence of failure of 2.4% when they advanced theneedle dorsodistally, directing it in a nearly a sagit-tal plane (Fig. 1).2 Generally, the first 3 to 5 mL ofanesthetic solution is easily injected. Forcing moresolution into the joint may cause a distinct “pop” andloss of resistance, indicating incorrectly that solu-tion has then entered the centrodistal joint. Formost horses, injection of fluid into the tarsometatar-sal joint under pressure causes the fluid to accumu-late subcutaneously rather than in the centrodistaljoint.2,3 The gait of some horses with lesions out-side the hock joint (such as lesions in the proximalportion of the suspensory ligament) may improveafter injecting local anesthetic solution into the tar-sometatarsal joint because medial and lateral out-pouchings of the joint on the plantar surface of thethird metatarsal bone (Fig. 2) may cause perineuralanalgesia of plantar and plantar metatarsal nerves,which lie in close proximity to these outpouchings.5

Because of the possible lack of specificity of anal-gesia of the TMT joint, some clinicians prefer todesensitize the CD joint to diagnose osteoarthritis ofthe distal tarsal joints.15 Although Serena et alshowed that a therapeutic concentration of methyl-prednisolone acetate is able to diffuse from the TMTjoint into the CD joint, some clinicians prefer todirectly inject the CD joint with a corticosteroid

because they believe the decreased concentration ofdiffused drug may have a decreased therapeuticeffect.16

Fig. 1. Using a plantarolateral approach to the tarsometatarsaljoint, a needle (A) is inserted above the head of the 4th metatarsalbone and directed in a dorsomedial direction. Approaching thetarsometatarsal joint by directing the needle (B) dorsodistally ina sagittal plane may increase accuracy of arthrocentesis of thisjoint.2 A right hock is shown.

Fig. 2. Medial and lateral outpouchings of the tarsometatarsaljoint may put local anesthetic solution in contact with plantarand plantar metatarsal nerves, causing anesthesia of structuresoutside the joint that lead to misinterpretation of analgesia of thetarsometatarsal joint block. A right hock is shown.

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Arthrocentesis of the CD JointThe CD joint can be injected by using dorsal, medial,or dorsolateral approaches, but regardless themethod of approach, arthrocentesis of the centrodis-tal joint is technically difficult. The joint can beentered at a site on the dorsal aspect of the hock ata site found by placing an index finger perpendicularto the long axis of the limb below the distal border ofthe easily palpated medial trochlea of the talus.a

The centrodistal joint should be in close proximity tothe ventral edge of the finger (Fig. 3). A 21-gauge,1-inch (2.5-cm) needle is inserted along this lineprobing for the joint space. For this approach, it isimportant that the horse stand squarely.

The CD joint can be entered on the distomedialaspect of the hock, midway between the plantar anddorsal aspects of the distal portion of the tarsus,with the limb bearing weight. The site of arthro-

centesis can be found by first identifying the easilypalpated distal tuberosity of the talus. Distal andplantar to this tuberosity is a less discernible emi-nence of the central tarsal bone. The site for needleinsertion is halfway between these landmarks and0.5 inch (1.3 cm) distal to the eminence of the centraltarsal bone.10 An alternate technique for identify-ing the site of needle insertion was described bySack and Orsini, who identified the site by imagin-ing a line between the palpable distal tuberosity ofthe talus to the palpable space between the secondand third metatarsal bones.2 The needle is in-serted near where the line intersects the palpabledistal border of the cunean tendon (Fig. 4). A 5/8-to 1-inch (1.6- to 2.5-cm), 23- to 25-gauge needle isinserted into the proximal part of the small,T-shaped gap formed by the junction of the fusedfirst and second tarsal bones, the third tarsal bone,and the central tarsal bone. This gap can usuallybe palpated using a fingernail. The needle shouldbe inserted as proximally as possible in this gap toavoid entering the TMT joint, which occupies thedistal portion of the gap.2 The site may be difficultto find, especially if the joint has severe degenera-tive disease. The needle is determined to be within

Fig. 3. The centrodistal joint can be entered at a site on thedorsal aspect of the hock at a site found by placing an index fingerperpendicular to the long axis of the limb below the distal borderof the easily palpated medial trochlea of the talus. The centro-distal joint should be in close proximity to the ventral edge of thefinger. Right hocks are shown.

Fig. 4. The centrodistal joint can be accessed on the distomedialaspect of the hock, midway between the plantar and dorsal as-pects of the distal portion of the tarsus, with the limb bearingweight. A technique for identifying the site of needle insertion isto imagine a line between the palpable distal tuberosity of thetalus to the palpable space between the second and third meta-tarsal bones. The needle (A) is inserted near where the lineintersects the palpable distal border of the cunean tendon. Toenter the talocalcaneocentral joint, a small gauge needle (B) isinserted proximal to the proximal border of the cunean tendon onthis line. A right hock is shown.



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the CD joint by low resistance to injection withoutdevelopment of subcutaneous swelling and the abil-ity to aspirate the injected contents of the syringe.Contrast arthrography confirms accurate arthrocen-tesis of the joint.9

Because the medial approach to the CD jointplaces the clinician in a vulnerable position for in-jury, some clinicians prefer a dorsolateral approachto this joint. As described by Just et al, the site ofinjection is 2 to 3 mm (�1/8 inch) lateral to the longdigital extensor tendon and 6 to 8 mm (1/4 to 1/3inch) proximal to a line drawn perpendicular to theaxis of the third metatarsal bone through the prox-imal end of the fourth metatarsal bone.16 The nee-dle is directed plantaromedially at an angle ofapproximately 70° from the sagittal plane (Fig. 5).

Arthrocentesis of the Tarsocural JointThe tarsocrural joint is the easiest of all joints of thehorse to inject. It is easily accessed at its dorsome-dial pouch on either side of the saphenous vein or ata lateroplantar pouch that protrudes between thecalcaneous and the lateral malleolus of the tibia(Fig. 6). By applying pressure to the dorsomedialpouch, the lateroplantar pouch may become moreobvious.

Arthrocentesis of the Talocalcaneocentral (ProximalIntertarsal) JointThe talocalcaneocentral joint is seldom accessed di-rectly because it communicates directly with thetarsocrural joint. The talocalcaneocentral joint canbe entered directly at a site along a line drawn fromthe distal tuberosity of the tibial tarsal bone to a

space between the head of the 2nd metatarsal boneand the 3rd metatarsal bone.17 A small-gauge nee-dle is inserted proximal to the proximal border of thecunean tendon on this line (Fig. 4).

Centesis of the Cunean BursaThe cunean bursa is occasionally injected with localanesthetic solution or with a corticosteroid whenbursitis of that structure is suspected to be a causeof lameness. The validity of cunean bursitis as acause of lameness, however, is questionable. Thecunean bursa occasionally communicates with theCD joint,9 which may explain why administration oflocal anesthetic solution or a corticosteroid into thebursa can temporarily resolve or ameliorate lame-ness in a horse whose lameness is caused by osteo-arthritis of the distal tarsal joints. Centesis of thecunean bursa is accomplished by inserting a needledirectly through the tendon into the bursa. Theneedle can also be inserted at the distal edge of thecunean tendon and directed proximally beneath thetendon, which travels in a proximodorsal, plantaro-

Fig. 5. A site of injection of the centrodistal joint is 2 to 3 mm(�1/8 inch) lateral to the long digital extensor tendon and 6 to 8mm (1/4 to 1/3 inch) proximal to a line drawn perpendicular to theaxis of the third metatarsal bone through the proximal end of thefourth metatarsal bone. The needle is directed plantaromediallyat an angle of approximately 70° from the sagittal plane. A righthock is shown.

Fig. 6. The tarsocrural joint is easily accessed at its dorsomedialpouch on either side of the saphenous or at a lateroplantar pouchthat protrudes between the calcaneous and the lateral malleolusof the tibia. By applying pressure to the dorsomedial pouch, thelateroplantar pouch (arrow) may become more obvious. A righthock is shown.

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lateral direction on the medial aspect of the hock(Fig. 7).

3. Conclusion

The distal tarsal joints are among the most fre-quently injected joints in horses, but the authors arenot aware of studies that have compared the accu-racy of techniques for arthrocentesis of these joints.The clinician should be aware that a positive resultof intra-articular analgesia of the CD or TMT joint isnot always an indication that there is disease ofthese joints and that negative results of intra-artic-ular medication may be the result of administrationof drug outside the joint, which may be unrecognizedby the clinician.

Acknowledgments

Figs. 1, 2, and 4 through 6 are adapted from MoyerW, Schumacher J, Schumacher J. Equine Joint In-jections and Regional Anesthesia, courtesy of Dr.

Amy Bentz, Academic Veterinary Solutions LLC.The authors thank Dr. Jay Addison for teaching usthe dorsal approach to the centrodistal joint.

References and Footnote1. Shively MJ. Correct anatomic nomenclature for the joint of

the equine tarsus. Equine Pract 1982;4:9–13.2. Sack WO, Orsini PG. Distal intertarsal and tarsometatar-

sal joints in the horse: communication and injection sites.J Am Vet Med Assoc 1981;179:355–359.

3. Kraus-Hansen AE, Jann HW, Kerr DV, et al. Arthrographicanalysis of communication between the tarsometatarsal anddistal intertarsal joints of the horse. Vet Surg 1992;21:139–144.

4. Bell BTL, Baker, GJ, Foreman JH, et al. In vivo investiga-tion of communication between the centrodistal and tarso-metatarsal joints in horses and ponies. Vet Surg 1993;22:289–292.

5. Dyson SJ, Romero JM. An investigation of injection tech-niques for local analgesia of the equine distal tarsus andproximal metatarsus. Equine Vet J 1993;1:30–35.

6. Dowling BA, Dart AJ, Matthews SM. Chemical arthrodesisof the distal tarsal joints using sodium monoiodoacetate in104 horses. Aust Vet J 2004;82:38–42.

7. Brown MP, Valko K. A technique for intra-articular injec-tion of the equine tarsometatarsal joint. Vet Med SmallAnim Clin 1980;75:265–270.

8. Gough MR, Munroe GA, Mayhew IG. Diffusion of mepiva-caine between adjacent synovial structures in thehorse, part 2: tarsus and stifle. Equine Vet J 2002;34:85–90.

9. Serena A, Schumacher J, Schramme MC, et al. Concentra-tion of methylprednisolone in the centrodistal joint after ad-ministration of methylprednisolone acetate in thetarsometatarsal joint. Equine Vet J 2005;37:172–174.

10. Moyer W, Schumacher J, Schumacher J. A Guide to EquineJoint Injection and Regional Anesthesia. Chadds Ford, PA:Veterinary Academic Solutions; 2011:52–61.

11. Gabel AA. Diagnosis, relative incidence, and probable causeof cunean tendon bursitis-tarsitis of Standardbred horses.J Am Vet Med Assoc 1979;175:1079–1085.

12. Gabel AA. Lameness caused by inflammation in the distalhock. Vet Clin North Am Large Anim Pract 1980;2:101–124.

13. Snow V. Equine roundtable discussion, part 3. EquinePract 1991;13:37–41.

14. Foerner J. Equine roundtable discussion, part 3. EquinePract 1991;13:37–41.

15. Bassage LH 2nd, Ross MW. Diagnostic analgesia. In: RossMW, Dyson SJ, editors. Diagnosis and Management of Lame-ness in the Horse. 2nd ed. Philadelphia: Saunders Elsevier;2011:100–135.

16. Just EM, Patan B, Licka TF. Dorsolateral approach forarthrocentesis of the centrodistal joint in horses. Am J VetRes 2007;68:946–952.

17. Dyson S. Intra-articular anaesthesia of the equine hock.In Pract 1985;7:92–96.

aAddison J. Independence, LA (personal communication), 2012.

Fig. 7. Centesis of the cunean bursa is accomplished by insert-ing a needle directly through the tendon into the bursa (B). Theneedle can also be inserted at the distal edge of the cunean tendonand directed proximally beneath the tendon (A), which travels ina proximodorsal, plantarolateral direction on the medial aspect ofthe hock. A right hock is shown.



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how to inject the tarsal joints · 2018-02-13 · pable anatomic landmark for needle placement is...

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