In-vivo pivot-shift test measured with inertial sensors correlates with the IKDC grade

Abstract

ObjectivesKinematic Rapid Assessment (KiRA) is a wireless, non-invasive, inertial system with a single tibial sensor developed to measure the pivot-shift (PS) test. The purpose of this study was to in-vivo compare acceleration values acquired by KiRA to the objective International Knee Documentation Committee (IKDC) clinical grading of PS. The comparison was performed in non-anaesthetised patients before and after anterior cruciate ligament (ACL) reconstruction. We hypothesised the existence of a correlation between the side-to-side difference in the measured acceleration range by KiRA and the objective IKDC clinical grading of the PS.MethodsBetween 2010 and 2014, 60 non-professional football players (male/female ratio: 42/18; mean age 34±15.4 years, range 14–51 years) with ACL lesion were enrolled. They underwent over-the-top ACL reconstruction plus lateral extra-articular plasty with autologous hamstrings. All the patients were evaluated before the reconstruction and re-evaluated at 12-month follow-up. Each patient underwent a clinical examination and then was subjected to the instrumental PS examination by KiRA. The difference in the acceleration range between injured/reconstructed and contralateral limb (Δarange) was used in the analysis. Correlations between Δarange values and objective IKDC clinical grades of PS were calculated using Spearman correlation analysis.ResultsAll subjective scores improved from preoperative to follow-up (P≤0.01). Objective IKDC clinical grading of the PS improved from 4B, 40C and 16D to 50A, 8B and 2C (P<0.0001). The mean Δarange measured by KiRA improved from 2.0±1.0 to 0.2±0.4 m/s2 (P<0.0001). A very strong correlation was displayed between the overall Δarange measured by KiRA and overall objective IKDC clinical grading of the PS (r=0.86, P<0.0001); correlation was strong for preoperative data (r=0.71, P<0.0001) and moderate for postoperative data (r=0.53, P<0.0001). The mean Δarange resulted 0.3±0.3 m/s2 for the IKDC A subgroup, 0.8±0.3 m/s2 for the IKDC B subgroup, 1.7±0.8 m/s2 for the IKDC C subgroup and 2.9±0.9 m/s2 for the IKDC D subgroup.ConclusionThe side-to-side difference in the measured acceleration range by KiRA shows a correlation with objective IKDC clinical grading of PS.Study designCase series; level of evidence: 4.