The Stroke Test – How To Objectively Measure Knee Joint Effusion

Commonly, knee joint effusion is qualitatively measured (minimal, moderate, etc) and that’s not very helpful because those terms don’t have much inter-rater reliability.  I don’t think most clinicians are aware that there is a simple, objective way to measure knee effusion called the stroke test.  The stroke test is very easy to perform/grade and has good inter-rater reliability.1

How to perform the stroke test for knee joint effusion:
  • Have the patient lie supine with both knees relaxed in full extension (if the patient is missing a significant amount of knee extension, you won’t get an accurate assessment)
  • Place your hands along the medial aspect of the proximal tibia and in a distal to proximal motion, sweep along the medial aspect of the knee up towards the suprapatellar pouch.  I usually do 2-3 sweeps consecutively (alternating hands).  You are trying to move the effusion out of the medial aspect of the knee.
  • After you finish sweeping, keep your focus on the medial aspect of the knee to see if any effusion returns on its own.
  • If nothing returns on its own, then perform a sweep from the lateral thigh downward past the lateral aspect of the knee.  Again, keeping your eyes focused on the medial aspect of the knee.
  • Typically, I repeat this 2-3 times and then also check the uninvolved side to see what the patient’s “normal” is.
How to grade the stroke test:

  • 0 – no wave produced with the lateral downward stroke
  • Trace – small wave with the lateral downward stroke
  • 1+ – large wave returns with lateral downward stroke
  • 2+ – effusion spontaneously returns to medial side after upstroke (without lateral downward stroke)
  • 3+ – so much fluid that it is impossible to move any of the effusion out of the medial aspect

How to use this information:
I look at and grade knee joint effusion for two reasons (the second reason is what I primarily use it for):
  1. To assess for the presence of intra-articular pathology.  Obviously, this isn’t the only thing you would look at to see if there is some type of intra-articular pathology, but it’s another piece to add to the puzzle.  And remember, an intra-articular pathology does not always have an associated effusion and vice-versa.
  2. To help me determine the appropriate progression (or regression) of a patient’s ther-ex/activity.  Typically, I use it this way on post-op knee patients.  You can use these effusion grades to help you determine progression/regression of your patient’s program, rather than have no real reason for doing so.  I should also mention that I use joint soreness rules in addition to the effusion rules for progression/regression of ther-ex/activity.  The effusion rules of progression/regression are:

    • Ther-ex/activity not progressed when there is a 2+ effusion or more.
    • If the effusion increases more than 2  grades or is now present when it was previously absent, ther-ex/activity is decreased to the level prior to the change in effusion.

The stroke test is a really simple test to perform/grade and it gives you objective data to help determine a patient’s ther-ex/activity progression.

Via Dr. Dennis Treubig, DPT – Modern Sports PT

1. Sturgill LP, Snyder-Mackler L, Manal TJ, Axe MJ. Interrater reliability of a clinical scale to assess knee joint effusion. J Orthop Sports Phys Ther. 2009;39:845-849.
Interested in live cases where I apply this approach and integrate it with pain science, manual therapy, repeated motions, IASTM, with emphasis on patient education? Check out Modern Manual Therapy!

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My interest in health and fitness started at a young age. Even though I had been educated and trained as an engineer in Europe I always want to follow my passion. I have made some guest appearances on a health educational program TV in Europe and, this experience, has made me follow my passion of sharing wellness information with others.

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