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Evidence-based knee and ankle examination (Part 1). Robbie Foy. Evidence based medicine.
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Evidence-based knee and ankle examination (Part 1) Robbie Foy
Evidence based medicine “… the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of patients… means integrating individual clinical expertise with the best available external evidence evidence” Sackett et al. BMJ 1996;312:70-71
What do we want out of a diagnosis? • Greater margin of certainty or safety • Rationale for clinical management • Better clinical outcomes • More efficient use of limited resources
Problems with diagnostic ‘tests’ • Lack of evidence • Quality of evidence • Timeliness of evaluations • Understanding of concepts and application • Getting evidence into practice
A review of diagnostic test evaluations • 184 studies evaluating 218 diagnostic tests • Only 7% of reviewed studies met all quality criteria • Accuracy of poorer quality evaluations over-estimated • Accuracy of poorer quality evaluations was over-estimated (in worst case) by up to three times Lijmer et al. JAMA 1999;282:1061-6
Back to school… Sensitivity: the probability of testing positive if the disease is truly present Specificity: the probability of testing negative if the disease is truly absent
The dummy’s guide SpIN High specificity helps rule a diagnosis IN SnOUT High sensitivity helps rule a diagnosis OUT
The McMurray Test To perform the test, the knee is held by one hand, which is placed along the joint line, and flexed to ninety degrees while the foot is held by the sole with the other hand. The examiner then places one hand on the lateral side of the knee to stabilize the joint and provide a valgus stress. The other hand rotates the leg externally while extending the knee. If pain or a "click" is felt, this constitutes a "positive McMurray test" for a tear in the medial meniscus. Likewise the medial knee can be stablized and the leg internally rotated as the leg is extended. A tag, caused by a tear will cause a palpable or even audible click on extension of the knee. A positive test indicates a tear of the lateral meniscus Wikipedia
Performance of the McMurray Test Sensitivity 53% Specificity 59% (Versus gold standard of arthroscopy)
Causes of variations in performance • Patient selection • Examiner specialty • Examiner skills and experience
The performance of composite examination Sensitivity 77% Specificity 91%
What do I want out of today? • To learn the best performing and most efficient combination of techniques to examine the knee • Including history taking • Specifically for meniscal injuries? • To increase my skills and confidence in applying these techniques
What do you want out of today? • Take a minute to write down 2-3 key learning objectives
What do you want out of today? • Take a minute to write down 2-3 key learning objectives • Take a minute to compare these with your neighbour
What do you want out of today? • Take a minute to write down 2-3 key learning objectives • Take a minute to compare these with your neighbour • Share some examples
Evidence-based knee and ankle examination (Part 2) Robbie Foy
“In almost all studies the process of care did not reach the standards set out in national guidelines or set by the researchers themselves.” Seddon ME, Marshall MN, Campbell SM, Roland MO. Qual Health Care 2001, 10:152-158. Bad doctors?
A psychological framework to think through changing practice Behavioural theory offers a basis for understanding clinical practice and thereby a rationale for strategies to change behaviour • Consensus process identified main constructs from 33 psychological theories and grouped them into 12 domains • Subsequent semi-structured interview schedule Michie S, et al. Qual Saf Health Care 2005;14:26-33
A psychological framework to think through changing practice
What did you get out of today? Were you able to meet your learning objectives? Did you change any of your learning objectives? • Discuss with your neighbour
What did you get out of today? Were you able to meet your learning objectives? Did you change any of your learning objectives? • Discuss with your neighbour How do you plan to put your learning into practice? • Discuss with neighbour • Share your suggestions