AIMSTo describe the techniques required to performaseptic arthrocentesis of the elbow joint. Thesetechniques can be used for injection of localanaesthetic into the joint when performingdiagnostic intra-articular analgesia. They are alsouseful for synoviocentesis to determine if infectivearthritis is suspected (Fig. 1). Additionally they can

be used to medicate the elbow joint with, forexample, intra-articular corticosteroids and hyaluronan.

ANATOMYThe elbow joint is formed between the distalhumerus and proximal aspects of the radius and ulna.The eccentrically placed collateral ligaments alongwith the concentric articulation between thetrochlea and trochlear notch restrict movement tothe sagittal plane1.The olecranon extends proximallya considerable distance above the elbow joint itself.The cranial joint pouch of the elbow extends fromthe supracondylar fossa of the humerus to theproximal radius. The caudal joint pouch extendscaudal to the humeral condyle thinning as it extendsproximal to the olecranon process. The ulnarislateralis bursa forms a synovial space between theulnaris lateralis muscle and the lateral coronoidprocess of the ulna. The ulnaris lateralis bursa hasbeen shown to communicate with the elbow joint in47.5% of joints in a cadaver study2 in which 40 jointswere injected with methyl methacrylate. Thereforethe approach to the caudal joint pouch through thisbursa is not recommended.

PREPARATIONA region approximately 10 cm2 is clipped over thesites described below. The injection site is thenaseptically prepared. A contact time between skinand dilute chlorhexidine scrub of 8-10 minutes isadequate. The skin is then soaked withchlorhexidine/alcohol and allowed to dry briefly.

EQUINE l ANAESTHESIA HUK Vet - Vol 11 No 3 April 2006 1

Sarah Taylor BVM&S CertES(Orth)MRCVSRESIDENT IN EQUINE STUDIES, ROYAL (DICK) SCHOOL OF VETERINARY STUDIES, UNIVERSITY OF EDINBURGH, EASTER BUSH, ROSLIN, MIDLOTHIAN. EH25 9RG

Intra-articular analgesia of the elbow joint

Figs. 1a and b: Arthrocentesis via thecaudal approach to determine the presenceof infective arthritis following a traumaticwound to the lateral aspect of the elbow.Photograph courtesy of Todd Booth.

Fig. 1b: Photograph courtesy of Todd Booth.

Fig. 2: Cadaver dissection of the cranial andcaudal approaches to the elbow. A. injectionsite cranial to the lateral collateral ligament.B. injection site following olecranon processof ulna.

AB

Sterile gloves are worn to draw up 10-20 mls ofmepivicaine (Intra-epicaine; Arnolds VeterinaryProducts Ltd) from a new vial. The needle used toaspirate the local anaesthetic is discarded. A sterile20-gauge spinal needle is used to perform thearthrocentesis. If synovial (joint) fluid does not dripfrom the needle following placement, gentleaspiration using a 2 mls syringe is necessary towithdraw synovial fluid to confirm the needle iswithin the joint.

TECHNIQUEThe use of (~1ml) subcutaneous local anaestheticcan be useful as manipulation and redirection of thespinal needle is often necessary to achieve elbowarthrocentesis. The following techniques becomemuch more technically demanding if a wound hasconcurrent swelling and oedema as anatomiclandmarks become more difficult to palpate.

CRANIAL JOINT POUCHThe cranial joint pouch is approached cranial to thelateral collateral ligament on the lateral aspect of thelimb with the limb weight bearing. The lateralcollateral can be palpated as a taut fibrous band(approximately 2.5 cm in diameter) extending fromthe humeral epicondyle to the lateral tuberosity ofthe radius. The spinal needle should be insertedcranial to the collateral ligament at a level of thedistal third of the ligament and directed slightlycaudally following skin penetration and advancedgently until bone contact is made (Diag. 1).Redirection of the needle is then possible to allowretrieval of synovial fluid.

CAUDAL JOINT POUCHThe landmarks for this approach are the cranialaspect of the olcranon and the lateral epicondyle ofthe humerus.The spinal needle is directed 45º fromproximolateral to distomedial and also slightly

cranially until synovial fluid is recovered (Diags. 1and 2). Some authors believe this approach avoidsdamage to the articular cartilage and consistentlyyields synovial fluid2. Additionally this approach canbe useful for horses that have a wound over thelateral collateral ligament and infective arthritis issuspected.

INTERPRETATION It is recommended that response to injection shouldbe interpreted soon after injection to avoid diffusionof local anaesthetic. A 50% improvement in thedegree of lameness 10 minutes after injection of localanaesthetic should be considered significant. Usingthe cranial approach temporary radial nervedysfunction has been reported following peri-articular injection of local anaesthetic; such horsesbecome unable to extend the carpus and distallimb3.

REFERENCES

1. DYCE et al (1996) The elbow joint and muscles of the arm.

2. SAMS et al (1993) Communication of the ulnaris lateralis bursa with

the elbow joint and evaluation of caudal arthrocentesis. Equine vet. J.

25(2); 130-133.

3. LEWIS (1996) Techniques for arthrocentesis of the shoulder, elbow,

stifle and hip joints. Proc Am Assoc Equine Pract 42; 55.

EQUINE l ANAESTHESIA H UK Vet - Vol 11 No 3 April 2006 2

Diag. 1: Lateral view of the elbow. Diagram representingthe cranial approach (A) and the caudal approach (B) to theelbow joint.

Diag. 2: Caudal view of the elbow. Diagramrepresenting the caudal approach to theelbow joint.

Humerus

Lateralhumeralepicondyle

Lateral collateralligament

Ulna

1cm

1⁄3

A

B

Extensorcarpiradialis

Commondigitalextensor

Radius

Humerus

Ulna

RadiusUlnarislateralismuscle

B