Read by QxMD icon Read

Analysis of Kneeling by Medical Imaging Shows the Femur Moves Back to the Posterior Rim of the Tibial Plateau, Prompting Review of the Concave-Convex Rule

Jennie M Scarvell, Nicola Hribar, Catherine R Galvin, Mark R Pickering, Diana M Perriman, Joseph T Lynch, Paul N Smith
Physical Therapy 2019 January 23

Background: Physical therapists assess joint movement by observation and palpation. New imaging technologies that enable vision of bones and joints during functional activities can be used to analyze joint kinematics and review traditional assumptions.

Purpose: The purpose was to measure relationships between flexion, rotation, and translation at the knee and to validate this visually.

Design: This was a prospective, observational study.

Methods: Twenty-five healthy participants over 45 years of age (13 males) knelt from upright kneeling to full flexion with the foot free. Fluoroscopy recorded movement at 30 frames per second of x-ray. A CT scan provided 3-dimensional data which was registered to the fluoroscopy frames to provide a moving model. Motion in 6-degrees-of-freedom was analyzed for coupling of movements.

Results: Participants reached 142 (6)° flexion in kneeling (mean [SD]). Posterior femoral translation was coupled to flexion (r = 0.96). From 90° to 150° flexion, the femur translated posteriorly by 36 (3) mm to finish 23 (3) mm posterior to the center of the tibia at 150° flexion. From 90° to 150° flexion, the femur externally rotated from 8 (6)° to 16 (5)°. Flexion was coupled to rotation (r = 0.47). Abduction was less than 3° and lateral translation was less than 3mm. Visually, the femur appeared to translate posteriorly until the femoral condyles rested on the posterior rim of the tibial plateau, with concurrent external rotation so that the popliteal fossa aligned with the posterior margin of the medial tibial plateau.

Limitations: A limitation of the study is that knee flexion can include squat and lunge as well as kneeling.

Conclusion: Deep flexion requires femoral posterior translation and external rotation. These findings invite review of the concave-convex rule as it may apply to manual therapy of the knee.


You need to log in or sign up for an account to be able to comment.

No comments yet, be the first to post one!

Related Papers

Available on the App Store

Available on the Play Store
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"