MIke T. John DDS, MPH, PhD; Ibtisam Al-Hashimi BDS, MS, PhD; John F. Bowley DDS, MS, CAGS
The systematic review found no clear evidence for a relationship between clinical and MRI diagnoses.
How does a diagnosis derived from patient history and clinical examination compare to a diagnosis derived from MRI in patients with TMJ disc displacement or (osteo) arthrosis?
A search of English-language literature in two databases combined with a hand search identified 23 studies. Search criteria used were the Medical Subject Headings (MeSH) “Temporomandibular Joint” and “Magnetic Resonance Imaging” limited to adult subjects from 1988 to 2007. Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool. Eight studies compared clinical (TMJ DD and/or OA) and MRI diagnoses. Measures for the relationship between clinical and MRI diagnoses varied, but five of the eight studies provided eight diagnostic odds ratios as a summary measure for diagnostic accuracy. A diagnostic odds ratio is the cross product of a 2 by 2 table comparing the presence of clinical and MRI diagnoses. It can also be calculated from test sensitivity and specificity. For example, if the clinical diagnosis of DD has 90% sensitivity and 75% specificity when compared with MRI, a diagnostic odds ratio of 27 would result. Sensitivity and specificity of 75% result in an odds ratio of 9. Higher odds ratios indicate stronger relationships between the two tests.
Five studies contained N=449 subjects. Their eight diagnostic odds ratios were all above 1 (=no relationship) except for one result (OR=0.88 for clinical vs. MRI diagnosed DD). Six odds ratios ranged from 0.88 to 5.15 for DD and internal derangement and two odds ratios were 5.29 and 10.26 for (osteo) arthrosis.
No clear evidence was found for a relationship between clinical and MRI diagnoses. The systematic review revealed a need for studies with improved quality in the reporting of samples, examination techniques, findings, and definitions and rationales for cutoffs, categories, and diagnoses and recommended standardized protocols such as the Research Diagnostic Criteria for temporomandibular disorders (RDC/TMD) and the Standards for Reporting of Diagnostic Accuracy (STARD) for future studies.
Source of Funding:
Importance and Context:
Patient history and clinical examination of the masticatory system are the foundation for diagnosing TMD. It is suggested that diagnoses of disc displacement and osteoarthrosis can be derived based on these findings. However, it is not clear whether these clinical diagnoses are accurate compared to MRI as the gold standard. If clinical diagnoses were sufficiently accurate, imaging would not be necessary.
Strengths and Weaknesses of the Systematic Review:
The search was sensitive and comprehensive but only English-language literature was included. Quality assessment of the studies was performed according to accepted guidelines. Article selection was performed by two independent reviewers, and their reliability for including abstract and publications was checked and found to be sufficient.
Strengths and Weaknesses of the Evidence:
The evidence for the relationship between TMJ clinical and MRI diagnoses suffers from the same problems as the TMD literature in general – diagnostic criteria are heterogeneous, often missing, and when present, reliability for them is not documented. Consequently, there was substantial variability in study design, clinical examination methods, and diagnostic criteria which this review revealed. The systematic review stated that there is no clear evidence for a relationship between TMJ clinical and MRI diagnoses because the results varied, but the question whether TMJ clinical diagnoses are accurate enough to diagnose TMJ status can be clearly answered: All observed diagnostic odds ratios were well below a value of 20 which may be considered a threshold for potentially useful tests (Fischer JE et al., Intensive Care Med. 2003). This indicates that clinical diagnosis of DD or OA is not accurate enough to replace MRI for proper diagnosis. In other words, imaging is still necessary to diagnose TMJ DD and OA status. Even when it is taken into account that MRI is an imperfect standard for diagnosing osteoarthrosis and the clinical diagnosis of osteoarthrosis should therefore have been compared with the gold standard CT, this statement is unlikely to change because the MRI diagnosis of osteoarthrosis is to a considerable degree predictive for a CT osteoarthrosis diagnosis.
Implications for Dental Practice:
When a diagnosis of TMJ disc displacement or osteoarthrosis is needed, patient history and clinical examination are not sufficient, and imaging using MRI and CT is necessary to diagnose TMJ intra-articular status. However, the clinician needs to keep in mind that pain and functional limitations of the TMJ matter the most to patients.