Intra‐articular injections in the TMJ inferior joint space: A scoping review

To perform a scoping review to identify the available evidence regarding intra-articular injections in the inferior joint space (IJS) of the temporomandibular joint (TMJ).An electronic search of the PubMed, Web of Science and Scopus databases was performed using the following terms: "Arthrocentesis", "injection", "joint injection", "technique", "Temporomandibular joint", "Temporomandibular joint disorder". Full-text articles were obtained from the records after applying the inclusion/exclusion criteria. Only articles with full-text access were included.Thirteen articles were included for analysis-one technical note, three cadavers studies, one animal study, two case reports, five randomised clinical trials and one retrospective study; studies were classified as 'patients-based studies' and 'non-patients-based studies'. Most 'patients-based studies' show moderate or high risk of bias. Techniques were categorised as 'anatomical technique' and 'image-guided technique'. Most 'patients-based studies' show favourable outcomes such as pain reduction, increase in maximum mouth opening, improvement in quality of life and improvement in TMJ dysfunction indexes for the treatment of arthrogenic TMDs. Comparisons between superior and IJS injections are scarce. On the other hand, 'non-patients-based' studies show that image-guided or ultrasound-checked injection techniques achieved a higher effectiveness for needle location than anatomical (or blind) techniques.The amount of available evidence is scarce, heterogeneous in design, and most 'patients-based studies' show moderate or high risk of bias, which demands the generation of new research to obtain definitive conclusions. The tendency observed suggests that intra-articular injections for the IJS of the TMJ are able to relieve TMJ pain, increase mouth opening and improve TMJ dysfunction, and image-guided injection techniques seem to be more effective than anatomical techniques to locate the needle in the IJS.