Accuracy and safety of two landmark-guided techniques for arthrocentesis and intra-articular injection of the shoulder in dogs

Objective: To determine the accuracy and safety of two landmark-guided techniques for shoulder arthrocentesis and injection. Study design: Ex vivo prospective study. Animals: A total of 36 paired canine cadaver forelimbs. Methods: An electronic survey was used to assess the prevalence of injection technique amongst surgeons in clinical practice. Thoracic limbs were randomized to technique for shoulder arthrocentesis and injection (subacromial [SA], n = 18, or supratubercular [ST], n = 18). Repositions, attempts, and the acquisition of synovial fluid was recorded. After the needle was placed, contrast was injected into the joint to determine accuracy of position. The radiographic presence of intra-articular contrast was judged as an accurate injection. Shoulders were disarticulated and India ink assay performed to assess for iatrogenic articular cartilage injury (IACI). Results: Both SA and ST techniques were not accurate. Completely accurate injection was identified in 50% SA and 44% ST (p =.80). IACI was identified in 50% SA versus 11% ST (p =.027). There were no significant differences in repositions, attempts, presence of synovial fluid (p =.5, p =.6, p =.7). Conclusion: Landmark-guided shoulder injections performed via SA and ST approaches in cadaveric dog shoulders are overall inaccurate. If performing landmark-guided shoulder injection, ST technique carries a lower risk of IACI than SA in cadaveric shoulders. Clinical significance: Landmark-guided shoulder injections are inaccurate in dogs and may result in treatment failure. A ST approach may be considered preferable due to the lower risk of cartilage damage. Future studies should assess ultrasound-guided techniques to improve accuracy and safety.