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How to Perform Direct Digital Radiography-Guided Navicular Bursa Injection

A. Kent Allen, DVM*; Susan Johns, DVM; Amy Norvall, DVM;and Meghan Breen, DVM

Authors’ address: Virginia Equine Imaging, 2716 Landmark School Road, The Plains, VA 20198;e-mail: [email protected]. *Corresponding and presenting author. © 2012 AAEP.

1. Introduction

Navicular bursitis is a common condition causinglameness in the horse. Injection of the navicularbursa with various medications is a common andeffective treatment for navicular bursitis. Thereare many techniques of variable efficacy described inthe veterinary literature for navicular bursa injec-tions.1 The limitation of these techniques is visu-alizing the placement of the needle and effectivelyinjecting into the bursa. There are few in vivo–guided techniques described in the veterinary lit-erature.2 Even when using anatomical guidelinesfor needle placement, radiographs are required toconfirm appropriate needle placement.2–9 Theradiograph-guided technique is simple, consistent,and effective. When using direct digital radiography(DR), images are obtained almost instantaneously,and the injection method becomes interactive. Be-cause most or all of the positioning of the needle isperformed before penetration of the deep digitalflexor tendon (DDFT), there is less iatrogenic injurycaused to this structure. However, to the authors’knowledge, this DR-guided technique has not beendescribed in the literature.

Since DR is now commonly used in equine prac-tice, many veterinarians have the required equip-

ment to perform radiograph-guided injection of thenavicular bursa and the technique is one that allveterinarians can easily learn. It is possible to useplain film and computed radiography for this tech-nique; however, the procedure will be slower and nottruly interactive. The purpose of this report is todescribe how to use both anatomical landmarks andDR to ensure successful injection of the navicularbursa.

2. Materials and Methods

This technique is performed when lameness hasbeen localized to the foot, using a thorough clinicalexamination including diagnostic analgesia, and na-vicular bursitis has been diagnosed either by ultra-sound or MRI.

3. Patient Preparation

Before performing the procedure, a proximal digital(abaxial) nerve block is performed with 2% mepivi-caine hydrochloride,a and the hair is clipped fromthe palmar pastern and heel bulbs using a No. 40blade. The site is then prepared in an aseptic man-ner. The horse should be adequately sedated withbutorphanol tartrateb (0.01 mg/kg IV) and detomi-dine HClc (10 �g/kg IV) before performing the pro-

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IMAGING: TAKING A BETTER LOOK INSIDE

NOTES

Orig. Op. OPERATOR: Session PROOF: PE’s: AA’s: 4/Color Figure(s) ARTNO:

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cedure. The amount of sedation depends on theattitude of the horse. The attitude of the horse alsodetermines whether additional restraint, such as atwitch, is necessary. The abaxial nerve block en-sures minimal movement of the patient during theprocess. In preparation for this procedure, propersafety precautions, such as wearing appropriatelead to protect against radiographic exposure, mustbe taken. After the sterile preparation, the horseshould be stepped forward onto a clean, level, dust-free surface. The area must also be dry to preventdamage to the DR panel. An assistant is used tosupport the limb to be injected, with the carpusslightly flexed and only the toe resting on theground. The solar surface of the foot is stabilizedagainst a block (the authors use a standing tunnel,2 inches high by 4 inches wide by 6 inches long).It is important that the assistant does not contami-nate the sterile area when handling the limb; there-fore, the assistant holds the metacarpus to stabilizethe foot against the block (Fig. 1). Placement of thefoot in this position allows the DDFT to relax andthe podotrochlear space to open. The more vertical

position of the flexor surface of the navicular boneallows for easier contact with the needle, and thereis increased distance between the injection site andthe ground, ensuring that the process remainssterile.1,4,7,10

4. Procedure

A 3.5-inch, 18- or 20-gauge spinal needle with styletd

is inserted along the median plane between the heelbulbs, approximately halfway between the distal as-pect of the pastern and the coronary band. Theneedle is angled between 45° and 55° from the floor

Fig. 1. Correct positioning of the limb before injection.

Fig. 2. Initial placement of the needle.

Fig. 3. Position of radiograph plate to assess needle placement.

Fig. 4. Initial lateromedial radiograph illustrating placementof needle before penetration of the DDFT (arrows).

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and directed toward a point 1 cm distal to the coro-nary band, halfway between the toe and the heel(Fig. 2).8,9

The needle is advanced until resistance from thepalmar surface of the DDFT is felt (approximately1.5 inches); the DDFT is not penetrated at this time.With a focal film distance of 24 inches, a latero-medial (LM) radiograph is performed to assess thepositioning of the needle (Figs. 3 and 4).

The needle should be directed toward the proxi-mopalmar aspect of the navicular bone. Beforepenetration of the DDFT, the needle should be re-directed according to the initial radiograph, and ad-ditional radiographs are performed until the

position of the needle is correct. The needle is thenadvanced through the DDFT to contact the navicu-lar bone (Fig. 5). A final LM radiograph is per-formed to confirm precise placement of the needlebefore the stylet is removed (Fig. 6).

At the proximopalmar aspect of the navicularbone, the navicular bursa reaches its maximumcross-sectional area. Positioning the needle at thispoint will ensure successful injection of the navicu-lar bursa and minimal iatrogenic injury to the na-vicular bone (Figs. 7 and 8).

In the authors’ experience, fluid is obtained in90% of the cases, either in the hub of the needle ordripping from the hub, depending on the amount ofeffusion present in the bursa (Fig. 9). Being carefulthat the needle is neither advanced nor retracted, itmay be necessary to twist the needle in place toobtain fluid. If no fluid is obtained and the radio-

Fig. 5. Anatomical specimen showing correct placement of theneedle on the proximopalmar aspect of the navicular bone.

Fig. 6. Lateromedial radiograph showing correct placement ofthe needle.

Fig. 7. Lateromedial radiograph showing a needle incorrectlypositioned on the flexor surface of the navicular bone.

Fig. 8. MRI showing correct position of the needle and signifi-cant anatomical structures.



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graph shows correct positioning of the needle, acouple milliliters of sterile 2% mepivicaine hydro-chloride or sterile saline may be injected into thebursa to get flow back from the needle. Contrastmaterial may be injected to confirm injection intothe navicular bursa but is typically not neces-sary.3,11 Carefully lifting the limb so that themetacarpus is parallel to the floor may facilitateobtaining fluid from the bursa as the soft tissuestructures around the bursa relax and the bursaexpands further. In rare cases, no fluid is obtainedfrom the bursa despite correct needle placement.In this situation, if the 2% mepivicaine hydrochlo-ride or medication injection flows easily, the pro-cedure is completed without obtaining fluid as aconfirmation of correct placement.

It is the authors’ preference to inject a cortico-steroid, such as 6 mg triamcinolone.e Differentamounts of corticosteroid may be used and maybe combined with hyaluronate and/or amikacin.3,5

Once the injection has been completed, the needle isswiftly removed and the injection site is wrappedwith sterile gauze sponges and cohesive bandagingtapef for 20 minutes.

5. Results

Using the technique described above ensures injec-tion of the navicular bursa rather than the distalinterphalangeal joint, DDFT, or digital cushion.1,7

In the previous 5 years (2007 to 2011), 225 horsesand 341 navicular bursae were injected with the useof this technique at the authors’ clinic. All caseshad a confirmed diagnosis of navicular bursitis,based on MRI and/or ultrasound findings before

treatment. Radiographs confirming the correctplacement of the needle, obtaining fluid from thebursa, and easy injection into the bursa all indicatedthat the injection technique was a success. Suc-cessful treatment of navicular bursitis with injectionof triamcinolone into the navicular bursa has al-ready been discussed in the veterinary literature.3

6. Discussion

It is essential that a diagnosis of navicular bursitisis made using the clinical examination, diagnosticanalgesia, and diagnostic imaging before treatment.Using this DR-guided technique ensures successfulinjection of the navicular bursa in 100% of cases.The guided approach described in this report workswell for a number of reasons. The technique issimple and straightforward, and the only specializedequipment required is DR (which is now commonlyavailable in equine practice). The procedure is sys-tematic, and once it has been completed a few times,the process becomes very efficient. DR allows repo-sitioning of the needle to occur within seconds, andthis technique ensures minimal iatrogenic injury tothe DDFT. A description of both a visual methodfor initial positioning of the needle and a DR-guidedmethod for advancement of the needle has been pro-vided. In addition, using DR guidance allows accu-rate placement of the needle, even in horses withabnormal foot conformation. Since this techniqueis used for treatment of navicular bursitis ratherthan for diagnostic analgesia, minimal movement ofthe horse is encountered during the procedure be-cause it is appropriately sedated and blocked withan abaxial nerve block. Finally, radiographs, ob-taining bursal fluid in the needle, and easy injectioninto the bursa are all confirmations of appropriateneedle placement.

In conclusion, this report has described a step-by-step process on how to accurately perform navicularbursa injections with interactive DR guidance inhorses diagnosed with navicular bursitis. With theuse of anatomical locations and LM radiographs, theneedle can be accurately directed to the bursa on theproximopalmar aspect of the navicular bone withminimal iatrogenic injury to the DDFT and flexorsurface of the navicular bone. Additional check-points confirm precise injection of the bursa. Thefinal radiograph taken once the needle is correctlyplaced can be kept in archives as proof of navicularbursa injection.

References and Footnotes1. Schramme MC, Boswell JC, Hamhougias K, et al. An in

vitro study to compare 5 different techniques for injection ofthe navicular bursa in the horse. Equine Vet J 2000;32:263–267.

2. Spriet M, David F, Rossier Y. Ultrasonographic control ofnavicular bursa injection. Equine Vet J 2004;36:637–639.

3. Bell CD, Howard RD, Taylor DS, et al. Outcomes of podo-trochlear (navicular) bursa injections for signs of foot pain inhorses evaluated via magnetic resonance imaging: 23 cases(2005–2007). J Am Vet Med Assoc 2009;234:920–925.

Fig. 9. Navicular bursa fluid dripping from the hub of the needle.

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4. Dabareiner RM, Carter GK, Honnas CM. How to performnavicular bursa injection and indications for its use, in Pro-ceedings. Am Assoc Equine Pract 2001;47:281–284.

5. Dabareiner RM, Carter GK, Honnas CM. Injection of cor-ticosteroids, hyaluronate, and amikacin into the navicularbursa in horses with signs of navicular area pain unrespon-sive to other treatments: 25 cases (1999–2002). J Am VetMed Assoc 2003;223:1469–1474.

6. Dyson SJ, Kidd L. A comparison of responses to analgesia ofthe navicular bursa and intra-articular analgesia of the distalinterphalangeal joint in 59 horses. Equine Vet J 1993;25:93–98.

7. Piccot-Crezollet C, Cauvin ER, Lepage OM. Comparison oftwo techniques for injection of the podotrochlear bursa inhorses. J Am Vet Med Assoc 2005;226:1525–1528.

8. Verschooten F, Desmet P, Peremans K, et al. Naviculardisease in the horse: the effect of controlled intrabursalcorticoid injection. J Equine Vet Sci 1990;10:316–320.

9. Verschooten F, Desmet P, Peremans K, et al. Naviculardisease in the horse: the effect of controlled intrabursalcorticoid injection. J Equine Vet Sci 1991;11:8.

10. Scrutchfield W. Injection of the navicular bursa. South-west Veterinarian 1977;30:161–163.

11. Turner TA. Use of navicular bursography in 97 horses, inProceedings. Am Assoc Equine Pract 1998;44:227–229.

aCarbocaine®-V, Pfizer, New York, NY 10017.bTorbugesic®, Fort Dodge Animal Health, Fort Dodge, IA

50501.cDormosedan®, Orion Corporation, Espoo, Finland.dBD Spinal Needle, BD, Franklin Lakes, NJ 07417.eVetalog® Parenteral, Bristol Myers Squibb S.r.l., Anagni (Fr),

Italy.fVetrap™, 3M Animal Care Products, St. Paul, MN 55144.





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