Measurements of knee rotation-reliability of an external device in vivo.
BACKGROUND
Knee rotation plays an important part in knee kinematics during weight-bearing activities. An external device for measuring knee rotation (the Rottometer) has previously been evaluated for validity by simultaneous measurements of skeletal movements with Roentgen Stereometric Analysis (RSA). The aim of this study was to investigate the reliability of the device.


METHODS
The within-day and test-retest reliability as well as intertester reliability of the device in vivo was calculated. Torques of 3, 6 and 9 Nm and the examiner's apprehension of end-feel were used at 90°, 60° and 30° of knee flexion. Intraclass Correlation Coefficient 2,1 (ICC 2,1), 95% confidence interval (CI) of ICC and 95% CI between test trials and examiners were used as statistical tests.


RESULTS
ICC2,1 ranged from 0.50 to 0.94 at all three flexion angles at 6 and 9 Nm as well as end-feel, and from 0.22 to 0.75 at 3 Nm applied torque.


CONCLUSIONS
The Rottometer was a reliable measurement instrument concerning knee rotation at the three different flexion angles (90°, 60° and 30°) with 6 and 9 Nm applied torques as well as the examiner's apprehension of end-feel. Three Nm was not a reliable torque. The most reliable measurements were made at 9 Nm applied torque.
Department of Health Sciences, Division of Physiotherapy, Lund University, Box 157, SE-221 00 Lund, Sweden. per.almquist@amadeushk.se
Per O
PO
Almquist
Charlotte
C
Ekdahl
Per-Erik
PE
Isberg
Thomas
T
Fridén
D000328:Adult; D000368:Aged; D053587:Arthrometry, Articular / Q000295:instrumentation*; D001696:Biomechanical Phenomena; D004867:Equipment Design; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D013548:Sweden; D019415:Torque; D016474:Weight-Bearing