Outcomes of Minimally Invasive TMJ Procedures: A New Quantitative Assessment Applied to 9 Published Studies

Abstract

In the last 4 decades, the effectiveness of minimally invasive TMJ surgery has been demonstrated in dozens of peer-reviewed articles, with typical success rates of 70-90%.1-4 However, a definition of “success” for TMJ surgery lacks standardization. Important parameters that are used to determine outcomes include changes in maximal incisal opening (MIO), an objective measure, and changes in pain (VAS), a subjective, patient-reported measure. Potential flaws in measuring surgical outcomes include the following: a) an increase in a patient's MIO may not occur with a decrease in pain, and conversely, reduction in pain may not be accompanied with an increase in MIO, b) the relative importance of each parameter is also dependent on the baseline value prior to surgery. The development of an outcome measurement that weighs both changes in MIO and pain in the assessment of success or failure has the potential to reflect the surgical outcome more accurately. The researchers developed an outcomes assessment system, the MIO-Pain Change Score (MIOPCS), combining objective and subjective parameters of success. The aim of this study is to determine if the MIOPCS applied to additional patient populations demonstrates a statistically significant positive correlation of success rates of minimally invasive TMJ arthroscopy utilizing methods described in previous published studies.The authors conducted a literature search for minimally invasive TMJ surgery (primarily arthroscopy) studies that included data on pre-operative and postoperative MIO and VAS scores as well as reported success rates. Nine papers and the data (a total of 10 populations) were identified, with populations between 17-344 patients (average of 123 patients per study, Table 1). The MIOPCS outcomes measurement is a numerical value that provides relatively equal weight to changes in MIO and VAS (MIOPCS = change in VAS + ½ change in MIO). Using this simple formula, the MIOPCS was calculated for the patient population in each study using the average changes in MIO and VAS reported. The MIOPCS and the reported success rates were graphed on a scatter plot, and a linear regression T-test was performed to determine the statistical significance (Figure 1).Based on the linear regression, there is a positive correlation between the MIOPCS and the reported TMJ surgery success rates. The linear regression demonstrated that for every point change in MIOPCS, there was a 2.9% change in success rate of the surgery (P = .0005) in these 10 study populations. The correlation coefficient was 0.89 with a coefficient of determination of 0.79.Applying the MIOPCS numerical measurement to data from 10 studies, there was a significant correlation between the MIOPCS and the authors’ reported success rates in the patient population. In the future, the MIOPCS outcomes assessment will be applied to additional populations to further determine the utility of the MIOPCS as simple, accurate, and valuable outcome assessment for TMJ surgery. The results of this early investigation are encouraging, providing evidence that the MIOPCS score has the potential for creating a more standard outcomes assessment for evaluating TMJ surgery.