Test-retest reliability of repeated knee laxity measurements in the acute phase following a knee trauma using a Rolimeter

Abstract

The purpose was to examine the test-retest reliability of the Rolimeter measurement procedure in the acute time phase, following a substan-tial knee trauma. In total, 15 participants with acute knee trauma were examined by one single observer at three different time-points with the Rolimeter using a maximum force. The selected time-points were: baseline (0-7 days after the trauma), midpoint (3-4 weeks after the trau-ma), and endpoint (3-4 weeks after the trauma). The anterior-posterior displacement was recorded where the endpoint evaluation was used as the reference value. The mean anterior laxity scores remained con-stant over the measurement time-points for both knees, with an anterior laxity that was 2.7 mm higher (on average) in the injured than the nonin-jured knee (9.5 mm vs. 6.8 mm). The mean difference (i.e., bias) between laxity scores, for the injured knee, measured at endpoint versus base-line was 0.2 ± 1.0 mm and -0.2 ± 1.1 mm when measured at endpoint ver-sus midpoint, with average typical errors of 0.7 and 0.8 mm and intra-class correlations that were very strong (both r = ~ 0.93). For the same comparisons on the noninjured knee, systematic bias was close to zero (0.1 ± 0.3 and -0.1 ± 0.3 mm, respectively), and both the intra-class cor-relations were almost perfect (r = ~ 0.99). The current study implicates that repeated Rolimeter measurements are relatively reliable for quanti-fying anterior knee laxity during the acute time-phases following knee trauma. Hence, the Rolimeter, in combination with manual tests, seems to be a valuable tool for identifying anterior cruciate ligament injuries.