Relationship between kinetics and knee muscle strength in patients with anterior cruciate ligament deficiency

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Relationship between kinetics and knee muscle strength in patients with anterior cruciate ligament deficiency

 

Author: Pang, Pik-yee
Title: Relationship between kinetics and knee muscle strength in patients with anterior cruciate ligament deficiency
Degree: M.Sc.
Year: 2001
Subject: Hong Kong Polytechnic University -- Dissertations
Motion
Knee -- Muscles
Muscle strength
Anterior cruciate ligament
Department: Multi-disciplinary Studies
Jockey Club Rehabilitation Engineering Centre
Pages: 111 leaves : col. ill. ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1637776
URI: http://theses.lib.polyu.edu.hk/handle/200/4690
Abstract: A landing maneuver has been proposed as an activity that commonly caused anterior cruciate ligament (ACL) injury resulting in functional instability and subsequent injuries to other musculoskeletal structures and early degenerative changes. Movement abnormalities that occur after ACL rupture may result from an inability to dynamically stabilize the knee. Nine males and one female with complete ACL tear were recruited. Each subject was asked to jump single-leg from a box of 300 mm high and land onto a force platform. Ground reaction force, kinetic and kinematic data of three landing trials were collected for both the uninvolved and the ACL deficient legs. Knee muscle strength was quantified isokinetically with testing velocities of 60o/s and l80o/s. Four different hamstring / quadriceps ratios, namely the concentric Hamstring / concentric Quadriceps ratio (H/Q ratio), eccentric Hamstring / concentric Quadriceps ratio (He/Qc ratio), concentric Hamstring / eccentric Quadriceps ratio (Hc/Qe ratio) and eccentric Hamstring / eccentric Quadriceps ratio (He/Qe ratio), were derived from the gravity-corrected peak quadriceps and hamstring torque using a standard dynamometer. It was found that for the uninvolved side, the H/Q ratio obtained at 180o/s remained the best torque ratio in predicting the landing performance as it showed the highest correlation with the peak vertical ground reaction force (r = 0.74, p = 0.015) and loading rate (r = 0.77, p <0.01). The He/Qc ratio obtained at l80o/s could provide additional information in predicting the time to peak vertical ground reaction force (r = -0.63, p = 0.05). The He/Qc ratio obtained at 60o/s showed a high correlation with the first knee extensor moment (r = 0.75, p = 0.031). For the ACL deficient knee, apart from observing the value of the H/Q ratio obtained at 180o/s, the value of the He/Qe ratio obtained at 60o/s should also be explored. The former ratio showed the highest correlation with the loading rate (r = 0.78, p < 0.01) while the latter showed a high correlation with the magnitude (r = -0.69, p = 0.029) and time to peak vertical ground reaction force (r = 0.72, p = 0.019). The Hc/Qe obtained at 180o/s and 60o/s showed high correlation coefficient in predicting magnitude and time to second knee extensor moment (r = -0.80, p = 0.03 and r = 0.90, p <0.01 respectively). The results suggested that different H/Q ratios correlated well with different characteristics of the landing task. Traditionally, the H/Q ratio obtained under the concentric mode was frequently used as indicator of muscle balance and functional ability of ACL deficient knee. However, the results of our study suggested that for the uninvolved side, the H/Q ratio obtained at 180o/s was the best indicator in predicting landing performance of the uninvolved side. For the ACL deficient knee, 'functional' H/Q ratios, i.e. He/Qe ratio obtained at 60o/s and Hc/Qe ratio that included both concentric and eccentric characteristics of the knee muscles in the calculation, were shown to be more informative in predicting the landing ability of subjects with ACL deficiency. These ratios are recommended to be included as part of the routine clinical assessment for the rehabilitation of patients with ACL deficiency. Further studies are suggested to explore the correlation between other isokinetic parameters with ground reaction force and the joint moment. Moreover, the effect of isokinetic training on each H/Q ratio and landing performance should be further investigated so as to obtain optimal performance gains, improve patient's functional instability and decrease the risk of injuiy due to landing.

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