According to this study's objective, the effectiveness of arthroscopy regarding pain and mandibular dynamics in patients with ID of the TMJ was evaluated, with the hypothesis that TMJ arthroscopy reduces pain and increases the maximum inter-incisal opening in this group of patients. In addition, variables such as age, sex, preoperative Wilkes stage and the level of arthroscopy performed were analyzed to determine whether they are related to the results.
The results of this study confirm the hypothesis that arthroscopy decreases pain and increases the maximum inter-incisal opening in patients with ID of the TMJ. Both the variation in pain and mouth opening were statistically significant for the follow-up periods studied. (Table 3) On the other hand, when analyzing the effectiveness of arthroscopy with the other variables, better results were observed for patients with lower Wilkes stages and for higher levels of arthroscopy performed. No association with age was found. The results of this study suggest that patients with less advanced stages of ID tend to have higher success rates from arthroscopic treatment techniques, in terms of pain and mouth opening, than those with more severe levels of disease, with results as soon as one month post-intervention. Therefore, the authors recommend early intervention as soon as an ID in the TMJ is detected[11].
Limited mouth opening and pain are the two most common reasons for consultation among patients with ID in the TMJ[1, 15]. Hence, the primary objective of treatment in this pathology is to resolve these parameters. A recent meta-analysis of different treatments for arthrogenic temporomandibular disorders by Al-Moraissi et al. [11] reported that in the medium term, minimally invasive procedures like arthroscopy are significantly more effective at reducing pain and increasing mouth opening in patients with ID of the TMJ than conservative treatments. This meta-analysis supports the paradigm shift toward minimally invasive procedures like first-line therapy for pain and mouth opening versus traditional concepts that attempt to exhaust more conservative treatment options[11]. Consistent with these results, both variables showed a statistically significant response in the patients with ID treated with arthroscopy in this study.
In this work, the success of the operation at the follow-up after one month was 75% for right TMJ and 73.4% for the left TMJ. Depending on the diagnosis and the success criteria used, the success rates reported in the literature range from 62–93%[7, 16, 17]. The reason for this may be based on the fact that studies with stricter criteria have lower success rates. Given these variations, it seems reasonable that the success criteria should be based on the patients' own levels of improvement in pain and pre-arthroscopy opening, more than the ranges established in the literature. Following this criterion, one month after arthroscopy, 88% of patients had reduced pain in the right TMJ and 90% in the left TMJ compared to pre-operative pain. Regarding mouth opening, the average increase was 3 mm with an average opening of 33 ± 5 at 3 months of follow-up and, while this is less than the normal opening values of 35mm, the increase in our group is statistically significant.
Though symptoms improved in all Wilkes stages, the analysis of the association between stages showed that less severe Wilkes stages had better results than more advanced stages. The success rates by Wilkes classification were 72% for Wilkes stage II, 64.0% for Wilkes stage III, and 70% for Wilkes stage IV. The literature currently available is not conclusive on this topic[10, 11, 18]. On the one hand, it has been suggested that patients with less advanced disease tend to have higher success rates when treated with arthroscopy and that cases with more severe disease need open surgery for optimal long-term results[18–21]. On the other hand, it has been argued that arthroscopy ultimately provides fewer benefits for stage II than for the most severely affected stages[10, 22]. However, there is a certain consensus in the literature that the management of ID with arthroscopy is more effective when undertaken closer to the appearance of symptoms[11, 18, 20].
In patients operated with bilateral arthroscopy, those who received level 3 arthroscopy had improved mouth opening after one month than those who underwent other levels. For the unilateral surgeries, both in the right as well as the left joint, no relationship could be observed between mouth opening at one month and the level of arthroscopy received, which could be due to the short follow-up period included in our study. González-García et al. [9] published a retrospective study comparing two arthroscopic techniques. They conclude that arthroscopy achieves a significant decrease in pain, with a simultaneous maximum mouth opening from the first month post-operation, without differences for the arthroscopic techniques studied. According to our studies, performance of level 3 arthroscopy produces better results in pain reduction than level 1 and patients who received level 3 arthroscopy had better mouth opening than those who received other levels, suggesting an advantage in the performance of arthroscopic discopexy to improve the mouth opening[23].
With the advance of arthroscopic skills and equipment, disc repositioning was developed to restore the proper anatomical relationship between the disc and the condyle in a minimally invasive way, thus alleviating the symptoms with fewer clinical complications and minimal need for hospitalization. A recent systematic review compared the effectiveness of open versus arthroscopic discopexy and concluded that both repositioning techniques led to a clinical improvement in terms of reducing pain and increasing the mouth opening[24]. However, arthroscopic disc repositioning is less invasive and associated with shorter hospital stays compared to open disc repositioning. On the other hand, the open approach allows for additional procedures to be performed, such as discoplasties, dissectomies and condylectomies and also offers direct access for the installation of anchorages[12].
In support of the paradigm shift described above, it is argued that early intervention offers more predictable results in terms of reducing the damage and achieving clinical improvements[11, 21]. It has been observed that a surgically induced disc displacement in animal models results in degenerative changes in the condylar cartilage and a reduction in its height[25]. Therefore, without early treatment, the disc can move into a more anterior position and greater deformity, resulting effusion and increased degeneration of the joint. For this reason, early restoral of the disc-condyle relationship through arthroscopic discopexy is important to prevent progression, alleviate and improve the symptoms with minimal invasion and low complication[26].
Our study’s main limitation is its retrospective nature, with the weaknesses inherent to this type of design with potential biases and loss of follow-up data, making long-term results difficult to analyze. However, it is a study with a considerable cohort, which analyzed demographic and clinical factors associated with the success and failure of the technique. In addition, quantified values of pain relief and increased mouth opening in patients with ID in the TMJ were given, rather than reporting success rates exclusively in percentages as is usually done. The authors recommend future studies based on randomized designs with a larger number of patients includes and longer follow-up times for an optimal interpretation of these results.