Evaluation of four techniques for injection of the proximal interphalangeal joint in horses

Objective: To describe a dorsoproximal midline (DPM) standing technique for proximal interphalangeal joint (PIPJ) injection and to compare it to established dorsolateral flexed (DLF), palmaroproximal (PP), and dorsolateral standing (DLS) techniques. Study design: Ex vivo study. Sample population: Sixty cadaver equine thoracic limbs. Methods: Limbs were divided into four groups (n = 15 each group), DLF, DPM, PP, and DLS. For each technique, three operators injected radiopaque contrast and methylene blue into the PIPJ in five limbs. The number of attempts required was recorded. Successful injection was confirmed by radiographic presence of contrast media within the PIPJ. Iatrogenic cartilage damage was assessed by gross examination. Statistical analysis was performed by Wilcoxon signed-rank test (P <.05). Results: The overall success rates were 86.6% to 93.3%. Although there was no difference in success rate, the frequency of needle repositioning was influenced by injection technique (P =.009). Dorsolateral standing had the highest mean ± SD value of attempts required to insert the needle in the joint space (2.62 ± 1.94). Injection technique influenced cartilage damage (P =.025), with the highest frequency recorded for DLS. Conclusion: All four techniques for injecting the PIPJ were highly successful; DLS was associated with the highest number of needle repositionings and the highest incidence of iatrogenic injury to cartilage. Clinical significance: Dorsolateral flexed should be considered as an alternative to the DLS technique to reduce iatrogenic cartilage injury when injecting the PIPJ. Dorsoproximal midline and DLF techniques have success rates comparable to traditional techniques, with lower incidence of iatrogenic cartilage damage in cadaver limbs.