The sitting active and prone passive lag test: a validity study in a symptomatic knee population

Area of Science:

• Orthopedics
• Sports Medicine
• Physical Therapy

Background:

• Terminal knee extension lag, a lack of full knee extension, can cause quadriceps overload, altered gait, and joint dysfunction.
• Accurate diagnosis of knee extension lag is crucial for effective patient management and rehabilitation.

Purpose of the Study:

• To evaluate the diagnostic accuracy of the sitting active and prone passive lag test.
• To determine the test's utility in identifying terminal knee extension lag in individuals with unilateral knee symptoms.

Main Methods:

• A randomized controlled trial design was employed with participants randomly assigned to test groups.
• Two blinded examiners assessed knee extension lag, assessing inter-rater reliability and diagnostic validity.
• Sensitivity and specificity of the test were calculated to determine its diagnostic performance.

Main Results:

• The sitting active and prone passive lag test demonstrated 'almost perfect' inter-rater reliability.
• The test exhibited high sensitivity and moderate specificity in identifying terminal knee extension lag.
• Results indicate strong diagnostic capability for the tested lag assessment.

Conclusions:

• The sitting active and prone passive lag test is a reliable and valid clinical tool.
• This test can be effectively incorporated into the assessment of unilaterally symptomatic knees.
• It aids in the diagnosis of terminal knee extension lag, informing treatment strategies.