TMJpathology: is it real?

Abstract

Clinical scenario: can poor athletic performance or behavioural problems, such as quidding, headshaking or dysphagia, be attributed to temporomandibular joint disorder (TMJ)? P (population) = adult horses with poor-/under-performance or behavioural problems and no other localising signs I (intervention/indicator) = clinical history and diagnostic testing (diagnostic imaging, arthrocentesis or intrasynovial anaesthesia, surgery) C (comparator/control) = N/A O (outcome) = diagnosis of poor performance attributable to the TMJ Search strategy Quantity of evidencePubMed result: 32 papers, including 12 single case reports or case series, 11 experimental studies of imaging (radiography, computed tomography, ultrasonography, magnetic resonance imaging), diagnostic (arthrocentesis) or surgical (arthroscopic) techniques (8 such studies used only cadaveric material, 7 used healthy live horses and 4 studies used both cadavers and live horses), 4 editorials or invited reviews, 2 experimental kinematic studies (1 technique validation and 1 measuring impact of dietary change), 2 studies of molecular biology (1 study of the correlation of TMJ cytokine profiles with dental pathology scores, and 1 of the cytokine response of TMJ compared to metarcarpophalangeal joints). Quality of the evidenceAn absence of systemic reviews, controlled clinical trials, case-control studies or large case series means that definitive evidence of TMJ disorder in horses is limited. This search used broad search terms, and only found mention of TMJ disorder amongst editorials and review articles. The experimental studies of diagnostic approaches are robust and provide good evidence for the benefits of advanced imaging modalities for this complex structure. Experimental evidence regarding the cytokine response in the TMJ indicates that this joint may show different cytokine dynamics to other diarthrodial joints (Carmalt et al. 2011), and does not definitively support the possibility of putative TMJ disorder contributing to the cluster of vague clinical signs listed. Dental pathology has been postulated as one cause of TMJ disorder; however, TMJ articular pro-inflammatory cytokine concentrations did not correlate with age and dental pathology score in one study (Carmalt et al. 2006). Can this evidence be applied in my case Clinical messageConfirmed reports of TMJ disorder in horses are absent, but this may be due to the diagnostic challenge that results from nonspecific signs. It is clear from this search that diagnostic techniques have progressed and should allow more specific diagnoses to be made. It is hoped that robust (multi-centre) case series will follow. Author's declaration of interestsNo conflicts of interests have been declared.

Long-Term Outcome of Horses Undergoing Unilateral Mandibular Condylectomy and Meniscectomy for Temporomandibular Joint Disease

“…Post-operative complications included serous or serosanguinous drainage from the incision (5 horses), swelling at the incision ( 5 ), formation of a sequestrum and draining tract at the incision ( 2 ), formation of an abscess ventral to the incision ( 1 ), signs of colic ( 2 ), and hyporexia ( 2 ) ( Table 3 ).…”

“…Prospective clinical trials, systematic reviews, or multi-center reports of TMJ disease (TMD) in horses are lacking because of the rarity of the disease and subtlety or ambiguity of clinical signs associated with TMD ( 4 – 6 ). The belief that lameness, or specific ill-behaviors, such as head-tossing, bit refusal, lameness, or unwillingness to travel in a specific direction ( 5 , 7 , 8 ), are caused by pain in the TMJ has resulted in a variety of empirical or holistic treatments, such as massage therapy, acupuncture, chiropractic adjustments, or dietary supplementation ( 9 ). Reported clinical signs displayed by horses with TMD include difficulties with mastication (quidding or hyporexia); pain when opening the mouth; effusion or swelling of the TMJ; headshaking; head tilt; and refusal to accept a bit when being ridden ( 8 , 10 – 14 ).…”