Knee-Extension Torque Variability and Subjective Knee Function in Patients With a History of Anterior Cruciate Ligament Reconstruction

Abstract

Context: When returning to physical activity, patients with a history of anterior cruciate ligament reconstruction (ACL-R) often experience limitations in knee-joint function that may be due to chronic impairments in quadriceps motor control. Assessment of knee-extension torque variability may demonstrate underlying impairments in quadriceps motor control in patients with a history of ACL-R.Objective: To identify differences in maximal isometric knee-extension torque variability between knees that have undergone ACL-R and healthy knees and to determine the relationship between knee-extension torque variability and selfreported knee function in patients with a history of ACL-R.Design: Descriptive laboratory study. Setting: Laboratory. Patients or Other Participants: A total of 53 individuals with primary, unilateral ACL-R (age ¼ 23.4 6 4.9 years, height ¼ 1.7 6 0.1 m, mass ¼ 74.6 6 14.8 kg) and 50 individuals with no history of substantial lower extremity injury or surgery who served as controls (age ¼ 23.3 6 4.4 years, height ¼ 1.7 6 0.1 m, mass ¼ 67.4 6 13.2 kg).Main Outcome Measure(s): Torque variability, strength, and central activation ratio (CAR) were calculated from 3-second maximal knee-extension contraction trials (908 of flexion) with a superimposed electrical stimulus. All participants completed the International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form, and we determined the number of months after surgery. Group differences were assessed using independent-samples t tests. Correlation coefficients were calculated among torque variability, strength, CAR, months after surgery, and IKDC scores. Torque variability, strength, CAR, and months after surgery were regressed on IKDC scores using stepwise, multiple linear regression.Results: Torque variability was greater and strength, CAR, and IKDC scores were lower in the ACL-R group than in the control group (P , .05). Torque variability and strength were correlated with IKDC scores (P , .05). Torque variability, strength, and CAR were correlated with each other (P , .05). Torque variability alone accounted for 14.3% of the variance in IKDC scores. The combination of torque variability and number of months after surgery accounted for 21% of the variance in IKDC scores. Strength and CAR were excluded from the regression model.Conclusions: Knee-extension torque variability was moderately associated with IKDC scores in patients with a history of ACL-R. Torque variability combined with months after surgery predicted 21% of the variance in IKDC scores in these patients.

Self-reported outcomes are associated with knee strength and functional symmetry in individuals who have undergone anterior cruciate ligament reconstruction with hamstring tendon autograft

“…IKDC score was found to be related to LSIs for concentric and eccentric knee extensor and flexor strength and related to single leg hop distance, but the correlations were only moderate. Our findings are consistent with previous findings, which have shown positive weak to strong associations between IKDC score and knee extensor strength in individuals who had undergone ACLR [14,35,36]. Zwolski et al [14] suggested that score of >94.8 on the IKDC is likely to indicate that a patient's quadriceps strength is at an acceptable level for RTS.…”

Do peak torque angles of muscles change following anterior cruciate ligament reconstruction using hamstring or patellar tendon graft?

“…[1] Past research has shown a significant postoperative deficit in isokinetic muscle test parameters such as peak muscle torque, total work and power which may lead to osteoarthritis. [2][3][4][5][6][7][8][9] These deficits were found to be associated with the location of the donor site. [10] Previous research has also focused specifically on the quality of torque production as demonstrated by isokinetic torque curve irregularities, curve fluctuations, a rapid downward slope pattern, and a concave pattern when viewed on a graph following ACL reconstruction.…”

Isokinetic moment curve abnormalities are associated with articular knee lesions

“…It is clear that preservation of joint stability is an important function of muscular co-activation, which provides the joint with some measure of stability in addition to the role of the ligaments. As consequence, it is reasonable that the failure to elicit the reflex creates an unfavourable background where the agonist muscle activation results are significantly inhibited or in latency [ 26 , 33 ], while antagonist muscle co-activation [ 30 , 34 ] seems to increase in amplitude and duration [ 35 , 36 ]. Even with the same joint configuration, the net mechanical effect of different loading conditions requires that the central nervous system adjust the strategy accordingly [ 37 ].…”