Orthopedic Test of The Month: The Stroke Test

Often when carrying out an examination multiple test will be performed. The checklist of orthopedic test can be endless. Multiple books and studies have been written regarding testing procedures. Furthermore, most test will have different names and variations which are open to subjective analysis. This is why research has shown the experience of the clinician to increase the diagnostic value of a test [1] Swelling is no exception to this rule.

How can you measure or grade swelling? What one deems to be significant swelling another may assess as minimal swelling. Due to this subjective nature it is often difficult for manual therapist to confirm or apply a grading system to swelling.

This Months Orthopedic Test: The Stroke Test (a.k.a Brush test, Wipe test, Bulge test)

When an injury occurs swelling will usually develop. Sever swelling outside of a joint can often be simple to see (See Pictures). However, whenever swelling occurs on a small level it can be difficult to assess and measure.

The knee joint normally holds 1-7ml of fluid within it's capsule. The stroke test has reported to show as little as 4-8ml of extra fluid within the knee. Occasionally when a knee has minimal intracapsular swelling the only observable feature is a puffy type of appearance. The patient may report a boggy sensation, an increased amount of pressure or assume a resting position of the knee. The resting position of the knee is when the knee will remain in a 15-25 degree flexed position. This position allows the knee capsule to hold the most amount of fluid and can be observed from the side of a patient while standing.

Multiple test have been purposed to measure swelling in the knee but no gold standard has been established. Measuring tape can lead to many forms of human error and subjective scrutiny. Although ultrasound and MRI have been deemed valuable ways of measuring swelling they are not always easily accessible for practitioners. Due to these reasons the stroke test can be a valuable method to not only diagnose swelling but to assess and be used in monitoring the progression of rehab exercises.

The stroke test is performed with the patient in a supine position and the knees fully extended and relaxed. The idea of the stroke test is for the examiner to create a fluid wave and displace the fluid in an area of the knee that allows the fluid to dissipate and pool. Starting at the medial tibiofemoral joint line, the examiner strokes upward 2-3 times towards the suprapatellar pouch in an attempt to move the swelling from within the joint capsule to the suprapatellar pouch. The examiner then strokes downward on the distal lateral thigh superior to the suprapatellar pouch, towards the lateral joint line. A wave of fluid may be observed along the medial side of the knee.The test can be measured in quantity on a 0-3 scale. If performing the downward stroke doesn't produce a wave of fluid a score of 0 is given. A small bulge produced with the down ward stroke is valued at 0 and a large wave 1+. If the medial fluid returns to its position without attempting a downward stroke a grade of 2+ is given and not being able to displace the fluid with an upward stroke is valued at 3+ .

The grading system has been shown to produce a high interrater reliability amongst practitioners [2]. Furthermore, the test creates a rating scale which can be used when relaying information to other professionals. In addition, creating a rating scale allows more precise measures and more specificity to be observed when researching or examining swelling of the knee.

1. David J Magee. Orthopedic Physical Assessment. 5th Ed

2. Sturgill L.P & al. Interrater reliability of a clinical scale to assess knee joint effusion. JOSPT. 2009, Vol 39, 12 845-849.