How to Inject the Medial Femorotibial JointRecess Under Ultrasound Guidance

Nick Kleider, DVM

Author’s address: Kleider Veterinary Services, Equine Clinic & Surgery, Langley, BC, V1M 3R8Canada; e-mail: kleidervet@gmail.com. © 2013 AAEP.

1. Introduction

Injection of the medial femorotibial (MFT) joint isfrequently a requisite for the diagnosis and manage-ment of equine lameness. The technique is impor-tant for the localization of lameness throughdiagnostic analgesia1 and the determination of thesignificance of pathology when identified on otherdiagnostic tests (imaging or arthroscopy). Further-more, joint injection is an inherent component oflameness management through the administrationof intra-articular medications ranging from chondro-protective agents, anti-inflammatories, and, morerecently, biological products. Although several dif-ferent injection techniques have been described,each method has some disadvantages. To circum-vent these disadvantages, the author has developedand will describe a technique for ultrasound-guidedinjection of the MFT joint that can be performedsolo.

Ultrasonographic examination reveals that thesize and depth of the MFT joint recess varies.a

Minimal effusion or fibrosis may result in a smallerrecess. Placement of a needle properly within therecess may not allow fluid to become visible at theneedle hub because proliferative synovial mem-brane may plug the needle or the needle size maybe too small relative to the viscosity of the synovial

fluid. If fluid is noted, the attachment of the nee-dle to the syringe followed by injection does notguarantee proper deposition of the medicationwithin the recess. Movement of the needle toodeeply results in deposition of the product beneaththe synovial membrane and too superficially into thesubcutus.

Recently, a detailed description of an alternativetechnique for injection of the MFT joint and relevantanatomy has been presented.2 This technique uti-lized a standard 1.5-inch, 20-gauge needle to injectthe MFT joint recess. The advantages of the tech-nique is that injecting the MFT joint recess, which islocated proximal to the meniscus, decreases the po-tential of needle contact with cartilage or the medialmeniscus. The disadvantages are (1) it is a blindtechnique relying on anatomical landmarks thatmay vary with limb positioning and (2) the tech-nique is dependent on noting fluid to be present atthe hub of the needle before injection.

Validation of a cranial injection technique withthe use of cadaver limbs was recently published3

that compared a cranial approach with a medialapproach to the MFT joint. However, the formerwas successful in approximately 50% of cases,whereas the latter was successful in only 93% whenno effusion was present.

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NOTES

The technique for ultrasonographic examinationof the MFT joint has been well described.3–6 Ultra-sound examination allows determination of the lo-cation, size, and depth of the MFT joint recess.Therefore, we used ultrasound monitoring to pre-vent inadvertent injection of the medial recess of thefemoropatellar joint.

This study describes the technique for solo ultra-sound-guided injection of the MFT joint recess andoverviews its use in 147 injections of 77 clinicalcases.

2. Materials and Methods

Seventy-seven horses undergoing this techniquewere tracked prospectively. Data were collected ontype of injection (diagnostic, therapeutic), dosageand volume administered, frequency of injection,and any complications.

TechniqueThe site for injection of the MFT joint recess isproximal to the medial meniscus, cranial to the me-dial collateral ligament, and caudal to the medialpatellar ligament.

The tail was wrapped, and the area was asepti-cally prepared. Clipping was usually unnecessaryin this area because of the sparsity of hair. Theultrasound machine was positioned caudally for con-venient viewing. We routinely used a 7.5-MHz lin-ear transducer and prepared it with acoustic gel anda sterile probe cover. A sterile syringe was filledwith the anesthetic, contrast, or medication to beused for the intra-articular injection, and a new 20-or 22-gauge needle was aseptically preplaced ontothe syringe.

When this procedure was used for the purpose ofdesensitizing the MFT joint during a lameness ex-amination, immobilization of the hind limb was fre-quently accomplished by lifting the ipsilateralforelimb. The horse was distracted at the time ofneedle insertion by having the owner feed the horsesome grain or horse treats. Most horses acclima-tized to having their stifles handled when given foodduring the scrubbing process. This form of re-straint was preferred to a twitch, which was onlyused in the horse that was not food-motivated and/orremained unruly. Horses that were difficult to jogreceived an extremely low intravenous dose of deto-midine HCLb (0.002 mg/kg). This allowed for moreconsistent jogging and less apprehension during theblocking procedure. Warm alcohol was applied tothe injection site and used as the external acousticmedium between the probe, within its sterilesheath, and the skin. The ultrasound probe wasplaced longitudinally over the medial recess (Fig. 1)by use of the three anatomical landmarks previouslymentioned as references. Once the recess wasidentified on the screen (Fig. 2) the probe was thenrotated 90° into a transverse position (Fig. 3). Theprobe could then be moved slightly proximally ordistally to ensure positioning over the most dis-

tended part of the recess (Fig. 4). A subcutaneous2-mL “bleb” of 2% lidocaine HCLc was injected ad-jacent to the cranial margin of the ultrasound probe(Fig. 5) with the use of a 27-gauge needle. This

Fig. 1. Step 1: Longitudinal positioning of the ultrasoundprobe and centering it on the MFT joint recess.

Fig. 2. Longitudinal reference sonogram of the MFT joint recessthrough the use of the craniomedial approach pictured inFig. 1. Proximal is to the left and distal to the right. 1, Femoralfascia; 2, MFT joint recess; 3, femoral condyle; 4, medialmeniscus.

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“bleb” was used as a landmark (Fig. 6) for replace-ment of the probe once the local anesthetic hadtaken effect and decreased any further discomfortthat could arise from introduction of the needle usedfor injection. The syringe with the 22-gauge needleattached was slowly introduced through the skin(Fig. 7) at the cranial margin of the ultrasoundprobe. The needle was pushed through the femoral

fascia into the recess, and the plunger was de-pressed (Fig. 8). The contents of the syringe wereobserved to enter the recess (Fig. 9). The syringeand needle were then withdrawn.

When the procedure was used to administer med-ications or for a contrast study of the MFT joint, thehorse was sedated intravenously with detomidineHCLb (0.01 mg/kg) and butorphanol tartrated

(0.01 mg/kg). Because food is not an incentive to asedated horse, the level of sedation was tested beforeinjection by carefully palpating the outer sheath or

Fig. 3. Step 2: Rotate the ultrasound probe 90° into a trans-verse position, staying centered over the MFT joint recess.

Fig. 4. Transverse reference sonogram of the MFT joint recessthrough the use of the craniomedial approach pictured inFig. 3. Cranial is to the left and caudal to the right. 1, Femoralfascia; 2, MFT joint recess; 3, femoral condyle.

Fig. 5. Step 3: Inject a 1- to 2-mL bleb of local anestheticcranial and adjacent to the probe.

Fig. 6. Step 4: Replace the probe transversely with the skinbleb used as a landmark.

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mammary area. Additional detomidine HCLb

(0.005 mg/kg) was given if required. Local anesthe-sia was frequently not necessary when this level ofsedation was used. The technique was similar ex-cept that a slightly larger needle (20-gauge) wasused to allow for easier injection of more viscousproducts. If the area was not desensitized, puttingslight pressure on the cranial aspect of the probe atthe time of needle insertion helped to prevent asurprise reaction from the horse.

The operator resisted the temptation of becoming“mesmerized” by the screen and focused on main-taining a parallel alignment between the syringeand probe. Malalignment resulted in losing sightof the needle, which also could occur by simply hav-ing a wet needle that is not sufficiently echogenic.Injection of a small test volume allowed visualiza-tion of fluid swirling and movement of echogenicgas/medication within the recess. The echogenicityof products that were not very echogenic was en-hanced by adding a small volume of air to the con-tents of the syringe when preparing the injections.

The technique is versatile and can be performedwith a microconvex or linear probe. A rectal probeis slightly more difficult to hold but has the advan-tage that no chord projects into a male horse’ssheath.

3. Results

One hundred forty-seven ultrasound-guided injec-tions of the MFT joints were performed on 77 horsesover a 3-year period. The signalment includedseven Thoroughbreds, 12 Standardbreds, nineQuarter Horses, and 49 Warmbloods, includingcrosses. There were 59 geldings, 16 mares, and twostallions. The median age was 8 years, with arange from 2 to 18, and the average age was 8.4years.

The time period between repeat injections into thesame joint varied from 1 day to 3 years. The leftMFT joint was injected in 49 horses and the rightMFT joint was injected in 20 horses. Fifty-four

Fig. 7. Step 5: While maintaining a parallel alignment be-tween the syringe and ultrasound probe, slowly drive the syringeneedle combination caudally through the skin bleb at approxi-mately 30° when using a linear probe.

Fig. 8. Step 6: Injection is commenced after entry through thesynovial membrane.

Fig. 9. Transverse sonogram of the MFT joint recess. The nee-dle is observed within the MFT joint recess (red arrows) andturbulent echogenic material (green arrow) is noted being ejectedfrom the needle tip into the fossa. Cranial is to the left andcaudal to the right.

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horses had bilateral injections. Seventy-sevenMFT joints received a single injection and 25 MFTjoints received multiple injections. Twenty-ninehorses had additional ultrasound-guided injectionsof the femoropatellar (FP) and/or lateral femorotib-ial (FT) joint in conjunction with the MFT joint(s).

Injectable products used were therapeutic and di-agnostic. Therapeutic agents included corticoste-roids,e,f,g,h chondroprotective agents,i and biologicalagents.j Diagnostic products included local anes-theticsc,k and contrast media.l Total volumes andproducts were variable. The total volume injectedranged from 3 to 20 mL. Combined products neverexceeded a volume of 15 mL, whereas single diag-nostic agents were injected at volumes up to 20 mL.

We found that ultrasound-guided needle place-ment and injection allowed monitoring of the needleposition and accurate drug deposition. Last, thetechnique was not dependent on the presence ofeffusion or on fluid acquisition; therefore, a smallerneedle could be used, which is less painful and lesstraumatic.

Insertion of the needle with the syringe alreadyattached was not problematic because the horse waseither sedated or had the insertion site desensitizedwith local anesthetic. Inadvertent movement re-sulted in a temporary delay in administration, nee-

dle withdrawal, or positional change but no needlebreakage. Movement was rare if the described re-straint procedures were followed. No infections oc-curred in this study. A slight learning curve wasnecessary to depress the plunger of the syringe withthe left hand for a right-handed operator when in-jecting the horse’s right stifle. Sitting on a rollingmechanic stool allows one’s hands to remain steadyand maintain more consistent alignment of needleand probe. Confirmation of the medication beinginjected into the recess was immediately noted byvisualizing the medication exiting the needle on theultrasound screen.

4. Discussion

Reasons for injecting the MFT joint include desen-sitization for the purpose of lameness diagnostics,therapeutic administration of medications, or con-trast studies. Contrast studies were recently initi-ated to see if there is communication between thefemoropatellar and MFT joint for the purpose ofselective administration of therapeutic medicationssuch as interleukin-1 receptor antagonist proteinj

(Fig. 10).This technique is similar to the blind technique

previously described,1 with the addition of ultra-sound monitoring with the use of an ultrasoundprobe placed caudal to the insertion site. Thisultrasound-guided technique was developed becauseof inconsistency or difficulty with previous tech-niques. Fluid is not always visible or obtainablewhen a blind technique is used. Obtaining fluiddoes not always provide assurance that the MFTjoint has been penetrated because the medial recessof a distended femoropatellar joint can lie adjacentto the MFT joint recess and may be inadvertentlypenetrated (Fig. 11).

Fig. 10. Contrast study of the MFT joint. Note the distendedMFT joint recess and no communication with the femoropatellarjoint in this horse.

Fig. 11. Transverse sonogram shows the close proximity of(1) the medial recess of the femoropatellar joint and (2) the MFTjoint recess. Cranial is to the left and caudal to the right.

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Ultrasound-guided injections allow for accurateneedle placement and drug deposition. They arefrequently performed by two operators, one holdingthe probe and the other guiding the needle into thebeam (ultrasound field of view). The spatial limi-tations of the medial aspect of the horse’s stifle doesnot allow for convenient maneuverability of two op-erators; therefore this technique for a solo operatorwas developed to overcome that obstacle.

Injection time was not recorded in this study butsubjectively appears to be less when ultrasoundguidance is used. The injection time was quiterapid with ultrasound guidance because there wasno delay associated with waiting for fluid to appearat the hub or incorrect manipulation of the needleinto the wrong plane or direction. On one bilateralcase, the time taken from application of the probe tocompletion of the injection was less than 30 secondsper side.

Simultaneous injection and ultrasound monitor-ing requires strict attention to maintaining the nee-dle in the ultrasound beam. If the needle tipdisappears from view, injection of a small amount ofmedication usually allows for rediscovery. Leavingthe needle attached allows for more sterility becausethe open hub of the needle is not exposed or manip-ulated. The majority of the population were geld-ings, and two stallions were included. Sheath orscrotal contamination of the back of the hand hold-ing the ultrasound probe can occur, but the syringehand remains guarded, and contamination of theinjection site was not a complication.

Because the needle is pre-attached, the whole pro-cess of watching the needle enter the recess and theadministration of its contents can be accomplishedvery rapidly. With the needle trajectory being con-stantly visible, redirection is easily accomplished.Clients enjoy visualizing the process and appreciatethe benefits of all upper-limb ultrasound-guided in-jections. This technique has become extremely

valuable because it is simple and ensures consistentintrasynovial injection of the MFT joint recess.

References and Footnotes1. Walmsley JP. The stifle. In: Ross MW, Dyson SJ, editors.

Diagnosis and Management of Lameness in the Horse.St Louis: Saunders; 2003:455–470.

2. Swiderski CE, Cooke E, Linford R. How to inject the medialfemorotibial joint: an alternate approach, in Proceedings.Am Assoc Equine Pract 2005;51:476–480.

3. Down SS, Munroe GA, Murray RC. Validation of a cranialinjection technique of the medial femorotibial joint in thehorse. Equine Vet Educ 2011;23:569–573.

4. Denoix JM. Ultrasonographic examination in the diagnosisof joint disease. In: McIlwraith WC, Trotter GW, editors.Joint Disease in the Horse. Philadelphia: Saunders; 1996:165–202.

5. Denoix JM. Ultrasonographic examination of the stifle inhorses, in: Proceedings. Annual Meeting of the ACVS 2003:122.

6. Hoegaerts M, Saunders JH. How to perform a standardizedultrasonographic examination of the equine stifle, in Pro-ceedings. Am Assoc Equine Pract 2004;50:212–218.

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land, QC H9J 2M5, Canada.cXylocaine, AstraZeneca Canada Inc, 1004 Middlegate Road,

Mississauga, ON L4Y 1M4, Canada.dTorbugesic, Pfizer Animal Health, Pfizer Canada Inc, Kirk-

land, QC H9J 2M5, Canada.eBetaject, Sandoz Canada, 110, de Lauzon, Boucherville, QC

J4B 1E6, Canada.fDepo-Medrol Sterile Aqueous Suspension, Pfizer Animal

Health, Pfizer Canada Inc, Kirkland, QC H9J 2M5, Canada.gKenalog*-10, Bristol-Myers Squibb Canada, 2344 Alfred-

Nobel Boulevard, Suite 300, Montreal, QC H4S 0A4, Canada.hPredef 2X, Pfizer Animal Health, Pfizer Canada Inc, Kirkland,

QC H9J 2M5, Canada.iMAP-5, Bioniche Animal Health Canada Inc, PO Box 1570

Belleville, ON K8N 5J2, Canada.jArthrex IRAP II System, Advanced Veterinary Products Can-

ada, 5500 Wharf Street, Sechelt, BC V0N 3A0, Canada.kCarbocaine-v 2%, Pfizer Animal Health, Pfizer Canada Inc,

Kirkland, QC H9J 2M5, Canada.lOmnipaque, GE Healthcare Canada Inc, 2300 Meadowvale

Boulevard, Mississauga, ON L5N 5P9, Canada.

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