Dynamic Evaluation of Lavage Efficacy in Upper Compartment of the Temporomandibular Joint

Abstract

The aim of this study was to determine the most efficient temporomandibular joint (TMJ) lavage technique for complete irrigation and removal of synovial fluid. The corresponding total lavage fluid volume needed also was investigated. Three-dimensional TMJ lavage models of the classic double- and single-needle techniques with modified cannula sizes (diameters, 2.4 and 0.8mm) were generated based on a constructed upper compartment model. Models were integrated with 2-phase flow models to predict fractional fluid volume (α value) changes of lavage saline and synovial fluid within the upper compartment of the TMJ. Fluid flow diagrams, velocity vectors, and intra-articular pressure data were collected and compared among the models. Models were validated by clinical synovial fluid concentration analyses, with vitamin B12 used as an internal standard. In all 8 models, lavage fluid initially gathered around the inflow portal, with a stable mixture of synovial and lavage fluids eventually being established in the compartment. Use of the double-needle technique with a large inflow portal resulted in thorough lavage (α= 100%). When the single-needle or Shepard cannula technique was used, some areas within the upper compartment remained devoid of brisk flow. The 2.4-mm inflow model coupled with a 0.8-mm outflow portal resulted in a stably and persistently high intra-articular pressure (>2.7 × 104Pa). A minimum volume of 109mL of lavage fluid was necessary for complete replacement of synovial fluid by saline. When a 2.4-mm inflow portal needle was applied, a lavage rate of 100% was obtained with a minimum lavage volume of 109mL. Using a small inflow portal could lead to inadequate flow, residual synovial fluid, and, ultimately, treatment failure.