Introduction

• Intrasynovial injection of anesthetic can desensitize all structures within and adjacent to the joint Anesthesia: intra-articular.
• Elimination of pain or lameness by intrasynovial anesthesia localizes source of pain to that joint, including surrounding structures.
• Approach to joints for synovial fluid collection Synovial fluid: collection is the same.

Uses

• More precise localization of source of pain following regional anesthesia.
• Establish the significance of imaging findings.
• Collection of joint fluid for gross or more specialized (chemical testing, culture, microscopic examination) analysis prior to anesthesia.

Advantages

• Minimally invasive technique.
• Useful to localize source of pain.
• Directs imaging, diagnosis, prognosis and treatment.
• Can be combined with intrasynovial medication.
• Septic synovitis is a relatively rare occurrence with appropriate aseptic and procedural techniques. Majority of intrasynovial injection techniques are easy to perform.
• Usually well tolerated by horses however fractious horses can complicate the procedure.

Disadvantages

• Risk of introducing pathogens → septic synovitis.
• Diffusion of local anesthetic solution and desensitization of extra-articular structures or adjacent nerves → false-positive results.
• Complete elimination of pain and therefore lameness may not be achieved.
• Need to delay anesthesia until regional effects of perineural analgesia have worn off and lameness has returned to baseline.
• Multiple joint entry can → soft tissue thickening or fibrosis.
• Response to more proximal joint analgesia is much slower than for distal joints adequate time must be allowed for complete action.
• The deep level of the hip joint and the proximity of the sciatic nerve makes anesthesia of the coxofemoral joint particularly difficult and potentially risky.
• Subchondral bone pain rarely responds to intra-articular anesthesia (false-negative results), eg subchondral bone cysts Bone: subchondral cysts, osseous cyst-like lesions Bone: osseous cyst-like lesions, some osteochondrosis lesions Bone: osteochondrosis, trabecular densification (third or central tarsal bones), chronic meniscal injuries Stifle: trauma - meniscal perineural analgesia is often required to locate site of pain.

Requirements

Preparation

Procedure

Aftercare

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Poore L A B, Lambert K L, Shaw D J & Weaver M P (2011) Comparison of three methods of injecting the proximal interphalangeal joint in horses. Vet Rec 168 (11), 302 PubMed.
• David F, Rougier M, Alexander K & Morisset S (2007) Ultrasound‐guided coxofemoral arthrocentesis in horses. Equine Vet J 39 (1), 79-83 PubMed.
• Schumacher J, Schumacher J et al (2003) The effects of local anaesthetic solution in the navicular bursa of horses with lameness caused by distal interphalangeal joint pain. Equine Vet J 35 (5), 502-505 PubMed.
• Schumacher J, Steiger R, Schumacher J et al (2000) Effects of analgesia of the distal interphalangeal joint or palmar digital nerves on lameness caused by solar pain in horses. Vet Surg 29 (1), 54-58 PubMed.
• Hendrickson D A & Nixon A J (1992) A lateral approach for synovial fluid aspiration and joint injection of the femoropatellar joint of the horse. Equine Vet J 24, 399-401 PubMed.

Other sources of information

• Moyer W, Schumacher J & Schumacher J (2011) Eds. Equine Joint Injection and Regional Anesthesia. In: Academic Veterinary Solutions. Chadds Ford, USA.
• Bassage L H & Ross M W (2011) Diagnostic Analgesia. In: Diagnosis and Management of Lameness in the Horse. Eds: Ross M W & Dyson S J. Elsevier Sunders, USA. pp 100-135.
• David F, Rougier M, Alexander K & Morisset S (2006) Ultrasound-guided coxofemoral arthrocentesis in horses. In: Proc ECVS Seville, Spain. Eds: Schramme M, Tremaine H, Walmsley J & Houlton J. ECVS, Zurich. pp 82-85.
• Dyson S (2006) Critical Evaluation and Review of Local Anaesthetic techniques for the Upper Hindlimb. In: Handbook of Presentations & Free Communications. BEVA Congress 2006. BEVA, UK. pp 33-34.
• Redding W R (2006) Critical Evaluation and Review of Local Anaesthetic techniques for the Lower Limb. In: Handbook of Presentations & Free Communications. BEVA Congress 2006. BEVA, UK. pp 28-30.
• Schumacher J, Livesey L, Schramme M C, Schumacher J & DeGraves F (2003) Effect of Anesthesia of the Palmar Digital Nerves on Lameness Caused by Pain in the Proximal Interphalangeal Joint. In: Proc 49th AAEP Convention. pp 287-290.
• Stashak T S (2002) Intrasynovial Anesthesia. In: Adams Lameness in Horses. 5th edn. Lippincott, Williams & Wilkins, USA. pp 168-180.