Bilateral medial tibiofemoral joint stiffness in full extension and 20 degrees of knee flexion.
BACKGROUND
The valgus stress test is used clinically to assess injury to the medial knee structures in 2 positions: full extension and some degree of flexion. The amount of flexion used to "isolate" the medial collateral ligament is not consistent in the literature, but most studies have shown that stiffness of the ligaments was consistent between the limbs.


OBJECTIVE
To determine (1) if the stiffness of the medial knee structures was the same bilaterally, and (2) if the stiffness was different in full extension compared with 20 degrees of knee flexion.


METHODS
Criterion standard, before-after design.


METHODS
University research laboratory.


METHODS
Both knees of 45 healthy and active volunteers (26 females, 19 males; age = 23.2 +/- 3.96 years, height = 170.6 +/- 7.75 cm, mass = 74.2 +/- 15.14 kg) were studied.


METHODS
A valgus force of 60 N was applied to the lateral aspect of both knees in full extension and in 20 degrees of flexion.


METHODS
The slope of the force-strain line of the medial knee during a valgus force was calculated using the LigMaster arthrometer.


RESULTS
Slope means in full extension were 16.1 +/- 3.3 (right knee) and 15.8 +/- 3.1(left knee). Means for 20 degrees of flexion were 12.2 +/- 3.1 (right) and 11.7 +/- 2.8 (left). Stiffness was greater when the knee was in full extension versus 20 degrees of flexion (t(44) = 12.04, P < .001). No difference was noted between the slopes of the 2 knees in extension (t(44) = 0.74, P = .46) or in flexion (t(44) = 1.2, P = .27).


CONCLUSIONS
These findings support the use of the contralateral knee as a control. Further, the valgus stress test should be performed in full extension and in some degree of flexion to assess the different restraining structures of the medial tibiofemoral joint.
Aronson
Patricia A
PA
Lynchburg College, Lynchburg, VA 24501, USA. aronson@lynchburg.edu
Rijke
Arie M
AM
Ingersoll
Christopher D
CD
D000328:Adult; D016118:Anterior Cruciate Ligament; D053587:Arthrometry, Articular; D017885:Collateral Ligaments; D005080:Exercise Test; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008023:Ligaments, Articular; D008297:Male; D017888:Medial Collateral Ligament, Knee; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D016119:Posterior Cruciate Ligament; D011446:Prospective Studies; D016059:Range of Motion, Articular / Q000502:physiology*