Biomechanical Analysis of Stair Locomotion in Patients with Anterior Cruciate Ligament Injury
Date Issued
2010
Date
2010
Author(s)
Lin, Hsiu-Chen
Abstract
The incidences of ACL tears were high in particular sports participations. The injury of the ACL could lead to anterior instability of the knee joint and substantial functional disability. The accurate diagnosis of ACL tear is vital to the following patient care. The regional analysis of the anterior knee laxity was used to show the differences of the anterior knee laxity between the normal and ACL-deficient knees. Two diagnostic criteria were developed based on our results: Region 2 with a displacement larger than 3.7 mm and Region 3 with stiffness smaller than 22 N/mm. They demonstrated good levels of both sensitivity and specificity in distinguishing the ACL-injured knees from possible ACL patients. Careful monitoring of functional recovery was essential for these patients before returning to sport activities. Investigation on stepping up and over test on a clinical forceplate system revealed the alterations in kinetic characteristics in ACL-deficient patients in different recovery phases. The results showed that the lift-up index, the time of swing-over and load-distributing strategy at impact could be important parameters in indentifying functional impairments for patients with ACL deficiency. These studies confirmed that, with a biomechanical approach, two assessments with instruments frequently used in clinics were presented and proved to be sensitive to the impairments in patients after ACL injury.
The lower extremity is a three-joint linkage system and stair locomotion is achieved through a complicated interaction of these joints. The knee joint is located in the middle of the linkage system and works sophisticatedly with the complex and interactive neuromusculoskeletal system. Injury of the ACL may change the relationship between these joints and the subsequent adaptations were expected. Three-dimensional kinematic and kinetic analyses of the lower limb joints during stair ascent and descent were performed on the patients with ACL deficiency and compared with the healthy controls. The results showed that these patients would adopt a protective strategy with slower cadences and reduced force-bearing on the affected limb. During stair descent, relatively larger magnitudes of the GRF parameters were also found in the affected limb than in the unaffected limb, which supported the responses in patients with ACL deficiency who would find it more challenging to perform stair descent. The kinematic adaptations during stair locomotion in patients with ACL deficiency were mainly made by the hip joint, with larger flexion and adduction, and less ER angles. A smaller range of motion at the ankle joint was also noticeable. Studies on control of the body stability and foot clearance during stair locomotion showed that the ACL-deficient patients demonstrated the increased posterior body center-of-mass-to-center-of-pressure (COM-COP) inclination and reduced medial COM-COP inclination during stair ascent. However, the ACL-deficient patients would reduce the body inclinations in both posterior and medial directions during stair descent. During stair ascent, the increased foot clearances in the trailing legs were demonstrated in the unaffected limbs, suggesting that because of the unstable stance leg, these patients may have to preserve a larger spacing from the obstacle under the condition without visual assistances. Further investigation on the kinetic alterations confirmed that ACL-deficient patients tended to leave a larger proportion of loadings on the three joints of the unaffected limbs and try to reduce those on the affected limb during stair locomotion. The anterior forces transmitted at the affected knees were found reduced significantly during stair ascent and descent. In response, the increased anterior forces were demonstrated at the ankles in both the affected and unaffected limbs. The reduced extensor moments were demonstrated at the affected knees in the early stance phase of stair ascent and descent. The corresponding adaptations occurred mainly in the hip and ankle joints of the unaffected limbs with increased hip abductor and ankle plantarflexor moments. Knowledge of the kinematics and kinetics of stair locomotion in the healthy young subjects and in patients with unilateral ACL deficiency were established. These investigations provided the insight in the adaptations during stair locomotion in the patients with unilateral deficiency, and could be used further in designing training programs or developing prevention strategies to avoid repeated injuries in the patients with unilateral ACL deficiency.
Subjects
Biomechanical analysis
anterior cruciate ligament
stair locomotion
kinematics
kinetics
Type
thesis
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