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- Kvist, Joanna, 1967-, et al.
(författare)
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Anterior positioning of tibia during motion after anterior cruciate ligament injury
- 2001
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Ingår i: Medicine & Science in Sports & Exercise. - 0195-9131 .- 1530-0315. ; 33:7, s. 1063-1072
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The purpose of this study was to describe the sagittal tibial translation and EMG activity of muscles v. medialis and lateralis, gastrocnemius, and hamstrings, during common locomotion, in patients with an anterior cruciate ligament deficiency (ACL-def) and uninjured controls.METHODS: In 12 ACL-def patients and 17 controls, sagittal tibial translation was registered with the CA-4000 electrogoniometer during level walking, cutting, and stair walking. Tibial position at each flexion angle was expressed relative to the femuro-tibial position at passive knee extension. EMG activity, measured with ME-4000, was normalized to the individual maximum isometric voluntary contraction for each muscle.RESULTS: During the weight-bearing phase of motion, the tibia was anteriorly positioned in all legs. In the injured leg, the tibia translated more rapidly to an anterior position that was maintained for a longer time during the gait cycle. In the noninjured knees, motions with increased load lead to an increased anterior tibial translation in contrast to the injured knees, where the maximum displacement was already reached during level walking. The quadriceps and gastrocnemius muscles were simultaneously active during stance phase. Hamstrings were mainly active when the knee was close to extension and translation increased in spite of this activity.CONCLUSIONS: The mechanism of the anterior positioning of tibia is qualitatively similar in the normal and the injured knee, but that position is obtained much further forward in the ACL deficient knee. Quadriceps and gastrocnemius muscles seem to work synergistically to stabilize the knee by maintaining the anterior position of tibia during weight-bearing motion. The role of hamstrings to restrict anterior translation is questioned.
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| 2. |
- Kvist, Joanna, 1967-, et al.
(författare)
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Anterior tibial translation during different isokinetic quadriceps torque in anterior cruciate ligament deficient and nonimpaired individuals
- 2001
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Ingår i: Journal of Orthopaedic and Sports Physical Therapy. - 0190-6011 .- 1938-1344. ; 31:1, s. 4-15
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Tidskriftsartikel (refereegranskat)abstract
- Study Design: Factorial quasi-experimental design.Objectives: To quantify the effect of different levels of isokinetic concentric and eccentric knee extensor torques on the anterior tibial translation in subjects with anterior cruciate ligament (ACL) deficiency. Electromyogram (EMG) activity of 4 leg muscles was recorded in order to detect any co-activation of extensors and flexors.Background: The rehabilitation after an ACL injury is of importance for the functional outcome of the patient. In order to construct a rehabilitation program after that injury, it is important to understand the in vivo relationships between muscle force and tibial translation.Methods and Measures: Twelve patients with unilateral ACL injury and 11 uninjured volunteers performed 36 repetitions of a quadriceps contraction at different isokinetic concentric and eccentric torque levels, on a KinCom machine (60°•s-1), with simultaneous recordings of tibial translation (CA-4000) and EMG activity from quadriceps and hamstrings muscles. Tibial translations and EMG levels were normalized to the maximum of each subject.Results: The individual anterior tibial translation increased with increased quadriceps torque in a similar manner in both quadriceps contraction modes in all legs tested. During concentric mode, translation was similar in all groups, but during eccentric mode, the mean translation was 38% larger in the ACL injured knees. No quadriceps-hamstrings co-activation occurred in any test or group.Conclusions: An ACL deficient knee can limit the translation within a normal space during concentric muscle activity but not during eccentric activity. That limitation depends on other mechanisms than hamstrings co-activation.
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| 5. |
- Kvist, Joanna, 1967-
(författare)
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Sagittal plane knee motion during activity in the anterior cruciate ligament deficient knee
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A complete rupture of the anterior cruciate ligament (ACL) results in static and often in functional instability. After an ACL-injury, most patients have to decrease their activity level, while some can cope with their injury and manage to keep a high activity level. A better tmderstanding of the influence of muscle activation and external load on the non-injured and injured knee, but also of the adaptive motion strategies employed by the patients with an unstable knee, is of importance for the construction of rehabilitation programs.The general purpose of this thesis was to study certain knee motions during activities focused on rehabilitation, in individuals with anterior cmciate ligament injury and uninjured controls. The sagittal tibial translation and knee flexion angle were registered during motion with the CA-4000 computerized electrogoniometer and EMG was used for analysis of muscle activity. The injured knee had increased static laxity compared to the contralateral non-injured knee and the non-impaired group.The amount of tibial translation increased with increased quadriceps torque during nonweight bearing activities (isokinetic and isotonic contractions). In the non-injured knees, the restraining mechanism was engaged above 50% of isokinetic concentric quadriceps torque and during the eccentric contractions already at low quadriceps torques (<10% of maximum). The motion pattern was similar in the injured knees and the amount of individual translation was larger during the eccentric contractions, compared to the non-injured knees.During weight bearing, tibia translated anteriorly and remained in that position. In the non-injured knee, different loads and performance of weight bearing activities produced different amount of translation. Level walking and squat with the center of gravity behind the feet produced somewhat smaller amount of translations, while other weight bearing activities produced similar amount of translation compared to the non-weight bearing isotonic knee extension. In the injured knee, all weight bearing activities produced similar amount of translation, smaller compared to the non-weight bearing isotonic knee extension.Quadriceps - hamstrings co-activation was not present during non-weight bearing quadriceps dominant activities and therefore, it was not shown to be a factor limiting anterior tibial translation. Also, during the weight bearing activities, hamstrings eo-contraction could not limit the anterior tibial translation. Quadriceps and gastrocnemius seems to work synergistically to stabilize the knee by maintaining an anterior position of tibia.In the injured knee, isokinetic concentric quadriceps contraction below 50% of maximum torque produced the smallest amount of tibial translation. Weight bearing exercises produced similar ammmt of translation despite of load and performance, indicating that when level walking is allowed after an injury, other weight bearing activities can be performed without increasing the amount of translation. Eccentric isokinetic quadriceps contractions above 50% of maximum torque and isotonic quadriceps exercise with and without weights at flexion angles less that 40°, should be avoided in order protect the knee joint.
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| 6. |
- Kvist, Joanna, 1967-, et al.
(författare)
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Sagittal Plane Knee Translation and Electromyographic Activity During Closed and Open Kinetic Chain Exercises in Anterior Cruciate Ligament-Deficient Patients and Control Subjects
- 2001
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Ingår i: American Journal of Sports Medicine. - 0363-5465 .- 1552-3365. ; 29:1, s. 72-82
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Tidskriftsartikel (refereegranskat)abstract
- Using electrogoniometry and electromyography, we measured tibial translation and muscle activation in 12 patients with unilateral anterior cruciate ligament injury and in 12 control subjects. Measurements were made during an active extension exercise with 0-, 4-, and 8-kg weights and during squats on two legs and on one leg where the projection of the center of gravity was placed over, behind, and in front the feet. In the uninjured subjects, tibial translation increased with increasing load except during the squat with the center of gravity behind the feet, which produced the smallest translation. For the active extension exercises, translation was greater during eccentric activity. In the anterior cruciate ligament-injured knees, all squats resulted in similar translation, which was smaller than that during the active extension exercise. The highest muscle activation was seen during squats. Hamstring muscle activity was low. Increased static laxity in the anterior cruciate ligament-deficient knee can be controlled during closed but not during open kinetic chain exercises. Coactivation of the quadriceps and gastrocnemius muscles seems to be important for knee stability, whereas hamstring muscle coactivation was insignificant. To minimize sagittal translation during nonoperative management of anterior cruciate ligament-deficient knees, closed kinetic chain exercises are preferable to open kinetic chain exercises, and importance should be attached to the spontaneous coactivation of the quadriceps and gastrocnemius muscles.
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