Rotational motion of the knee*

Abstract

This study deals with the quantitation of axial rotation at the knee. Passive rotation of the knee was measured at various degrees of flexion on 17 subjects with normal knees and 19 patients with unilateral anterolateral rotatory instability. Normal subjects were found to have bilateral symmetric rotational knee motion at each angle of flexion tested. When the knee is in a position of flexion between 30 and 90 degrees, there are approximately 45 degrees external and 25 degrees internal rotation. Rotatory motion decreases with further extension and, at 5 degrees of flexion, the knee has 23 degrees external and 10 degrees internal rotation. The knee with a torn anterior cruciate ligament and anterolateral rotatory instability was found to have an arc of rotation similar to the contralateral knee and to the control knees between 30 and 90 degrees flexion. At 15 degrees of flexion, a slightly greater arc of rotation was measured compared to normal knees. At 5 degrees of flexion, a significantly greater range of external (to 41 degrees) as well as internal (to 14 degrees) rotation was measured.

Evaluation of an external device measuring knee joint rotation: an in vivo study with simultaneous Roentgen stereometric analysis

“…Zarins et al [20] have measured knee rotation with the subject lying on one side. The knee was positioned and measured at angles of 90°, 60", 30", 15" and 5" of flexion.…”

Objective measurements of static anterior and rotational knee laxity

“…Cadaveric studies revealed that the section of the ACL led to 2.4 to 4°increase in rotation in knee flexion angles below 30° [ 69,70]. Above this degree of flexion, the increase in rotation induced by the lesion was not detectable anymore [25,71]. Early in vivo studies demonstrated a similar increase of rotation in the injured knee by 10 % (3°) compared to the healthy knee [72].…”

“…Most researchers apply this torque from internal to external rotation or from external to internal rotation to obtain a complete cycle of rotation. A solution to avoid the hysteresis phenomenon, which comes along with this technique and influences the reproducibility of the measurements [25,26], is to perform separate measurements of internal and external rotation and to include Bpreconditioning trials.R otational knee laxity is influenced by the patient's position and by the location of rotation measurement. Knee rotation is higher if the knee is flexed at 90°compared to 20°and if the hip is extended compared to the flexed position at 90° [ 27].…”

The Effect of Tibial Rotation on the Presence of Instability in the Anterior Cruciate Ligament Deficient Knee

“…3 The effect on tibial rotation of cutting the ACL has been well reported. 4,5,6,7 In a cadaveric study, 4 total (internal and external) rotation at 10 and 30 degrees of knee " exion increased signi! cantly after the ACL was cut.…”

“…9,10 Therefore, severing the ACL greatly increases the amount of tibial rotation. On the other hand, a study that compared ACL injured knees with normal knees by using a Cybex dynamometer 4 to measure rotational motion showed injured knees had signi! cantly greater external and internal rotation compared to normal knees (!…”