Syllabi - Physiotherapy Practice - Diagnosis Scenario
Anita Gross, Ted Haines, Diane Hartley.Read the article and decide:A 24 year old woman with a gradual onset of left temporomandibular joint (TMJ) pain after yawning 10 days ago, reports severe worsening over the past 5 days resulting in a change to a soft diet. Her past history reveals recurrent episodes of jaw joint locking. Clinical findings are reduced mouth opening (maximum active opening 35mm, passive opening 36 mm), right laterotrusion (5mm) and a reproducible reciprocal click (early on opening and late on closing). There is no crepitus. Some local muscle tenderness exists (masseter, medial pterygoid). There is reduced joint play. Tomography results in the medical record demonstrated diminished anterior translation of both condyles. No osseous changes were noted. The clinical impression is internal derangement. You wonder if your diagnosis is correct, so you develop the following question and make plans to search MEDLINE:
"Is your clinical impression of temporomandibular joint disorder (internal derangement) correct for your patient with the following clinical [history of locking, preauricular pain, reproducible and reciprocal click, local muscle tenderness, reduced joint play, reduced mouth opening (35 mm) plus tomography findings (diminished anterior translation of both condyles, no osseous changes)? Is this diagnostic impression important for clinical management?"
You do a MEDLINE search (1988 - 1998) using the MESH heading 'temporomandibular joint disorders' and find one article assessing a cluster of clinical tests and tomography.
Citation
Schiffman EL, Anderson GC, Fricton JR, Burton K, Schellhas KP. Diagnostic criteria for intrarticular temporomandibular disorders. Community Dent Oral Epidemiol 1989;17:252-257.
- Is the evidence from this study valid for the clinical diagnosis?
- If valid, is this evidence important?
- If valid and important, and if your patient was shown to have internal derangement, can you apply this evidence in caring for your patient?
Completed Diagnosis Worksheet for Evidence-Based Physiotherapy Practice
Citation
Schiffman EL, Anderson GC, Fricton JR, Burton K, Schellhas KP. Diagnostic criteria for intrarticular temporomandibular disorders. Community Dent Oral Epidemiol 1989;17:252-257.Are the results of this diagnostic study valid?
- Was there an independent, blind comparison with a reference ("gold") standard of diagnosis?
- A blind comparison was made. However, it is not clear if the reference test (arthrotomography) was performed independent of the clinical tests.
- The validity of the reference standard is not specified. No convincing evidence was provided in the article to support that this test is the best reference or gold standard. There is some evidence that MRI is the best reference standard.
- Was the diagnostic test evaluated in an appropriate spectrum of patients (like those in whom it would be used in practice)?
- A representative mix of cases appears to be present.
- Was the reference standard applied regardless of the diagnostic test result?
- Yes
Are the valid results of this diagnostic study important?
Your calculations:
- Study Setting: tertiary care
- Target disorder: internal derangement
- Reference standard: arthrotomography
- Diagnostic test: diagnostic criteria for intraarticular TM disorder (Table 3 of the paper) included positive history of mandibular limitation, no reciprocal click, no coarse crepitus, maximum opening less than or equal to 35 mm, passive opening stretch less than 40 mm, contralateral movement less than 7 mm, no S-curve deviation and tomography findings of decreased translation of the ipsilateral condyle.
| Internal Derangement of TMJ | ||||
|---|---|---|---|---|
| Present | Absent | |||
| Diagnostic Criteria (Sample A) |
Positive | 42 a |
2 b |
a + b |
| Negative | 7 c |
8 d |
c + d |
|
| Totals | a + c 50 |
b + d 10 |
||
| Schiffman et al 1989 (Sample A) |
|||
|---|---|---|---|
| Sensitivity* = a/(a+c) | 0.86 | ||
| Specificity* = d/(b+d) | 0.80 | ||
| Likelihood ratio for a positive test = LR+ = sens/(1-spec) | 4.30 | ||
| Likelihood Ratio for a negative test = LR- = (1-sens)/spec | 0.18 | ||
| Positive Predictive Value = a/(a+b) | 0.96 | ||
| Pre-test Probability (prevalence) = (a+c)/(a+b+c+d) | 0.83 | 0.50 | 0.20 |
| Pre-test odds = prevalence/(1-prevalence) | 4.88 | 1.00 | 0.25 |
| Post-test odds (+ test) = Pre-test odds x LR+ | 20.99 | 4.3 | 1.08 |
| Post-test odds (- test) = Pre-test odds x LR- | 0.86 | 0.18 | 0.05 |
|
Post-test Probability (+ test) = Post-test odds/(post-test odds +1) |
0.95 | 0.81 | 0.52 |
|
Post-test Probability (- test) = Post-test odds/(post-test odds +1) |
0.46 | 0.15 | 0.05 |
| * Sensitivity and specificity are reported in the text and the marginal total for a+c and b+d were reported in table 2. No further data were available to allow for extraction of the 2x2 table (cells a, b, c, d). The highlighted segments of the above table reflect the Schiffman et al 1989 sample A results. To assist the reader in applying these clinical findings, the additional calculations present calculations for a low (e.g. 0.20) and intermediate (e.g. 0.50) pre-test probability / prevalence. | |||
Can you apply this valid, important evidence about a diagnostic test in caring for your patient?
- Is the diagnostic test available, affordable, accurate, and precise in your setting?
- Yes. History, clinical evaluation and tomography are commonly available, affordable, done accurately (the imaging protocol would need to be determined per site) and precisely in our community.
- Can you generate a clinically sensible estimate of your patient's pre-test probability (from practice data, from personal experience, from the report itself, or from clinical speculation)?
- This is dependent on the reader's data management system available in the practice setting. The prevalence in the study sample was 0.83.
- Will the resulting post-test probabilities affect your management and help your patient? (Could it move you across a test-treatment threshold?; Would your patient be a willing partner in carrying it out?)
- Yes. If the pretest probability is a toss-up (e.g. 0.50) the post-test probability for positive test results firms up to 81%. However, if the pretest probability is low (e.g. 0.20), neither a positive nor a negative test result brings the post-test probability into a range where intervention would likely change (0.05, 0.52 respectively). Similarly, for the high pretest probability (e.g. 0.83, as in Schiffman et al 1989) a negative test result does not exclude internal derangement (post-test probability = 0.46) and a positive result further confirms your previous strong clinical impression. The tests are of minimal risk to the patient and therefore one should be willing to carry them out.
- Would the consequences of the test help your patient?
- Marginally to definitely. Yes depending on the prevalence of ID in your practice setting. The treatment for internal derangement differs to some extent in physiotherapy management from other TMD. It would be more informative if the LR+ for each subgroup (for example: internal derangement with reduction and without reduction) were reported.
Additional Notes
- In Schiffman et al 1989, the assumption is made that there were no missing data. Table 4 notes that 10% of the normals of sample A and 27% with the disorder were not classifiable. This is contrary to table 2 where the sample number are noted to be as follows:
target disorder present n = 50 target disorder absent n = 10 - see also Schiffman E, Haley D. Sensitivity and specificity of diagnostic criteria for temporomandibular internal derangements. J Dent Res 1994;73(1 NSI): 440.
Temporomandibular Joint Disorders: Clinical exam may be helpful in the diagnosis:
Clinical Bottom Line
If the pre-test probability is intermediate (e.g. 50%), the post-test probability for positive test results increases to 81%. The validity of the reference standard was not specified in the article; there is evidence that MRI may be the best reference standard.Citation
Schiffman EL, Anderson GC, Fricton JR, Burton K, Schellhas KP. Diagnostic criteria for intrarticular temporomandibular disorders. Community Dent Oral Epidemiol 1989;17:252-257.Clinical Question
Is your clinical diagnosis of: internal derangement correct when presented with a patient with the following clinical [history of locking, preauricular pain, reproducible and reciprocal click, reduced mouth opening (35 mm), local muscle tenderness, reduced joint play] and tomography findings (diminished anterior translation of both condyles, no osseous changes)?Search Terms
You do a MEDLINE search (1988 - 1998) using the MESH heading 'temporomandibular joint disorders' you find one article assessing a cluster of clinical tests and tomography.The Study
- Gold Standard - A reference test (arthrotomography) was used. A blind comparison was made. However, it was not clear if the reference test was performed independently of the clinical tests. The validity of the reference standard was not specified.
- Study Setting - tertiary care
The Evidence
| Diagnostic Criteria | Internal Derangement | No Internal Derangement | Likelihood Ratio |
|---|---|---|---|
| Present | 43/50 | 2/10 | 4.30 |
| Absent | 7/50 | 8/10 | 0.18 |
| 50 | 10 |
If the pre-test probability is intermediate (e.g. 50%) then a positive clinical test would be helpful, yielding a post-test probability of 81%.
If the pre-test probability is low (e.g. 20 %) then the clinical test is not useful (post-test probability = 52%).
Comments
- Diagnostic test: diagnostic criteria for intraarticular TM disorder (Table 3 of the paper) included positive history of mandibular limitation, no reciprocal click, no coarse crepitus, maximum opening less than or equal to 35 mm, passive opening stretch less than 40 mm, contralateral movement less than 7 mm, no S-curve deviation and tomography findings of decreased translation of the ipsilateral condyle.
- Uncertain if the reference standard that was used was the best available
- Unclear if the reference standard performed independently of the clinical tests
