TY  - JOUR
A1  - Huang, Hongshi
A1  - Guo, Jianqiao
A1  - Yang, Jie
A1  - Jiang, Yanfang
A1  - Yu, Yuanyuan
A1  - Mueller, Steffen
A1  - Ren, Gexue
A1  - Ao, Yingfang
T1  - Isokinetic angle-specific moments and ratios characterizing hamstring and quadriceps strength in anterior cruciate ligament deficient knees
JF  - Scientific reports
N2  - This study is intended to find more effective and robust clinical diagnostic indices to characterize muscle strength and coordination alternation following anterior cruciate ligament (ACL) rupture. To evaluate angle-specific moments and hamstring (H)/quadriceps (Q) ratios, 46 male subjects with unilateral chronic ACL-rupture performed isokinetic concentric (c), eccentric (e) quadriceps and hamstring muscle tests respectively at 60 degrees/s. Normalized moments and H/Q ratios were calculated for peak moment (PM) and 30 degrees, 40 degrees, 50 degrees, 60 degrees, 70 degrees, 80 degrees knee flexion angles. Furthermore, we introduced single-to-arithmetic-mean (SAM) and single-to-root-mean-square (SRMS) muscle co-contraction ratios, calculating them for specific angles and different contraction repetitions. Normalized PM and 40 degrees specific concentric quadriceps, concentric hamstring strength in the ACL-deficient knee were reduced significantly (P <= 0.05). Concentric angle-specific moments together with Qe/Qc ratios at 40 degrees (d = 0.766 vs. d = 0.654) identify more obvious differences than peak values in ACL ruptured limbs. Furthermore, we found SRMS-QeQc deficits at 40 degrees showed stronger effect than Qe/Qc ratios (d = 0.918 vs. d = 0.766), albeit other ratio differences remained basically the same effect size as the original H/Q ratios. All the newly defined SAM and SRMS indices could decrease variance. Overall, 40 degrees knee moments and SAM/ SRMS ratios might be new potential diagnosis indices for ACL rupture detection.
Y1  - 2017
U6  - https://doi.org/10.1038/s41598-017-06601-5
SN  - 2045-2322
VL  - 7
PB  - Nature Publ. Group
CY  - London
ER  -