Validade e confiabilidade do dinamômetro isométrico Medeor® para avaliação da força de quadríceps e isquiotibiais após reconstrução do ligamento cruzado anterior

Abstract

The muscular strength of the quadriceps and hamstrings is widely used as a criterion for return to sports after anterior cruciate ligament (ACL) reconstruction, serving as a predictor for a lower risk of ACL re-injury. The isokinetic dynamometer is the gold standard method for assessing muscular strength. However, its high acquisition cost hinders its widespread use in clinical practice. Therefore, the handheld dynamometer (HHD) stands out for its feasibility, portability, and low cost. The aim of the study was to verify the intra-rater and inter-rater reliability of the HHD and its validity for assessing isometric strength of quadriceps and hamstrings at 45° knee flexion compared to the isokinetic dynamometer (gold standard) in patients with ACL reconstruction. A prospective reliability and validity study was conducted at the Human Movement Analysis Laboratory (LAMH) of the Department of Physical Therapy at the Federal University of Ceará (UFC) from November 2022 to October 2023. Intra-rater and inter-rater reliability of isometric strength of quadriceps and hamstrings at 45° knee flexion were measured by two blinded evaluators in relation to each other's results (evaluator A and B) and re-evaluated after 5-7 days (evaluator A). For validity, the strength assessment on the HHD with MEDEOR® equipment was first performed, followed by the assessment of peak torque (PT) of quadriceps and hamstrings on the Biodex® isokinetic dynamometer at 60°/s. The isometric dynamometer showed good intra-rater reliability for knee extension and flexion (ICC = 0,863 and ICC = 0.852, respectively), and excellent inter-rater reliability for extension (ICC = 0,961) and flexion (ICC = 0,957) of the knee. The agreement limits (LOA) was 5.63, while the standard error of measurement (SEM) was 1.13 N m/kg, and the minimum detectable change (MDC) was 3.14 N m/kg. The isometric dynamometer at 45° knee flexion demonstrated good validity with PT on the isokinetic dynamometer for knee extension and flexion (r = 0,624; P < 0.001). The assessment of quadriceps and hamstrings strength using the isometric dynamometer at 45° knee flexion is a valid and reliable option compared to the isokinetic dynamometer in patients who have undergone ACL reconstruction surgery.