Puncture points related to the tragal-lateral canthus line in conventional temporomandibular joint arthrocentesis: are they accurate? A cadaver study

Purpose To evaluate the technical success of conventional TMJ arthrocentesis in cadavers, using the tragal-lateral canthus line as an anatomical reference for the puncture points. Methods Ten formalin-treated and 8 fresh cadavers were submitted to the arthrocentesis. A point located 10 mm anteriorly and 2 mm inferiorly to the beginning of the tragal-lateral canthus line (A) and another point 20 mm anteriorly and 10 mm inferiorly (B) were demarked on the cadavers’ skin. Following, 1 mL of methylene blue solution was injected through the needle at point A, and then another needle was placed at point B. Saline solution was injected through the first needle, identifying a free flow of bluish solution. Results Concerning the formalin-treated cadavers, TMJ arthrocentesis was not successfully performed in any case (0%). In the fresh cadavers, the procedure was properly conducted bilaterally in only one case (12.5%) and unilaterally in 3 cases (37.5%), 2 on the left side (25.0%) and one on the right (12.5%). Conclusion The traditional points related to the tragal-lateral canthus line seemed not to be accurate references for the insertion of the needles in conventional TMJ arthrocentesis when 1 mL of solution is used initially and the maximum mouth opening is not achieved.