Knee Extension Lag

Original Editor - Ajay Upadhyay

Top Contributors - Laura Ritchie, Kim Jackson, Ajay Upadhyay, Nehal Shah, Admin, Evan Thomas, WikiSysop, Wanda van Niekerk and Lauren Lopez  

Purpose

The term ‘muscle lag’ or ‘extensor lag’ or ‘quadriceps lag’ is a clinical sign with often profound functional relevance for patients during knee rehabilitation.

Technique

An active lag was determined by the inability of the erectly seated subject to actively extend the involved knee in maximal dorsiflexion of the ankle to the same level as the normal knee held in maximal extension and ankle in maximal dorsiflexion, as seen by the levels of the toes.

A passive lag was determined by placing the subject prone with the knees just past the edge of the table and determining the high position of the heel in a fully resting extension position compared to the heel on the normal side.

Evidence

For the sitting active lag test, the inter-rater reliability was 'good' (Kappa 0.792, SE of kappa 0.115, 95% confidence interval). For the prone passive lag test, the inter-rater reliability was 'good' (Kappa 0.636, SE of kappa 0.136, 95% confidence interval).

Resources

Sebastian D, Chovvath R, Malladi R. The sitting active and prone passive lag test: an inter-rater reliability study.J Bodyw Mov Ther. 2014 Apr;18(2):204-9.

Recent Related Research (from Pubmed)

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References

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