Leeds Institute of Health Sciences

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

Disease present

Disease absent

Total

Test positive a b a+b

Test negative c d c+d

Total a+c b+d a+b+c+d

The dummy’s guide

SpIN

High specificity helps rule a diagnosis IN

SnOUT

High sensitivity helps rule a diagnosis OUT

Fear of the McMurray Test

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

The Chinese Banquet Menu Syndrome

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

Leeds Institute of Health Sciences

Evidence-based knee and ankle examination (Part 2)

Robbie Foy

Bad doctors?

“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.

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

Domain Illustrative questions

Knowledge Do you know why you are doing X?

Skills Do you know how to do X?

Professional role Should you be doing X?

Self-efficacy How confident are you about doing X?

Beliefs about consequences What will happen if you do X?

Motivation and goals How much do you want to do X?

Memory and attention Will you remember how to do X?

Environment and context Are there competing tasks and constraints?

Social influences Do your colleagues / patients expect you to do X?

Emotion How do you feel about doing X?

Behavioural regulation What preparatory steps are needed to do X?

Nature of the behaviour What is X?

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