| Background:The three-dimensional kinematic stability of the knee joint after anterior cruciate ligament reconstruction(ACLR)is of great significance for maintaining the health of the knee joint,delaying the degeneration of articular cartilage and preventing re-injury in patients with ACLR.However,the three-dimensional kinematic stability of the knee joint in patients with ACLR under comprehensive motion tasks has not been clearly elucidated.The anterior tibial translation(ATT)is a key indicator reflecting the effect of ACLR surgical intervention.So far,the impact of ATT on the three-dimensional kinematic stability of the knee joint has not yet been clearly elucidated.In addition,how to carry out the knee three-dimensional kinematic stability analysis of the ACLR as a clinical routine has important clinical significance for the diagnosis and treatment of ACLR.Variable speed walking and slope walking(special test exercise tasks)may be feasible and promising methods to adapt to the clinical environment to detect the stability of ACLR knee kinematics,but whether they can detect the kinematics stability of ACLR knee joint has not been verified.Therefore,this study intends to investigate the three-dimensional kinematic stability of the knee joint of ACLR subjects in different exercise tasks and special test exercise tasks,the differences in the three-dimensional kinematic stability characteristics of the knee joint of ACLR subjects in different ATTs,and the possibility of clinical routine of the knee three-dimensional kinematic stability analysis of the ACLR.This study hypothesizes:(1)ACLR patients have differences in the three-dimensional motion instability characteristics of the knee joint in different motion tasks;(2)ATT can affect the threedimensional kinematic stability of the ACLR knee joint,and the mechanism is that ACLR surgery restricts the movement of the femoral lateral condyle,ATT leads to the corresponding three-dimensional motion instability characteristics of the knee joint;(3)ACLR subjects can show the characteristics of knee joint kinematic instability during variable speed walking and slope walking.Study Part 1: ACLR Knee Kinematic Stability in Low-demanding Motion Tasks and Differences between Different Anterior Tibial TranslationsMethod:In this study,subjects with single-bundle anatomical ACLR reconstruction were recruited,and the three-dimensional motion parameters of the knee joint of ACLR patients in the sit-stand task and walking were collected by the knee joint three-dimensional kinematics analysis system.The three-dimensional kinematic stability indicators of the knee joint include varus/valgus angle(°),internal/external tibial rotation angle(°),flexion/extension angle(°),anterior/posterior tibial translation(mm),distal/proximal tibial translation(mm),medial/lateral tibial translation(mm).The ATT of ACLR subjects was measured by joint and ligament digital physical examination instrument,and the ATT difference between the affected side and the healthy side was sorted from high to low.The first 50% was the relaxation group,and the last 50% was the tension group.Basic clinical data of ACLR subjects,knee X-ray review(joint degeneration and tibial retroversion),clinical function scores and other information to characterize the characteristics of the ACLR population were collect analyzed whether there are differences in clinical information between the relaxation group and the tension group.Results:(1)Basic clinical information of ACLR subjects:A total of 55 subjects were included in this study.The mean ± standard deviation of age was 30.6 ± 6.4 years old,the mean ± standard deviation of height was 173.5 ± 6.6 cm,the mean ± standard deviation of weight was 72.7 ± 10.1 kg,and the mean ± standard deviation of BMI(body mass index)was ±24.1±2.8kg/m2.The follow-up was 22.6 ± 19.9 months postoperatively.The average ATT difference(reconstructive-healthy side)in the tense group(27 cases)was-0.3±0.9mm,and the ATT difference in the relaxation group(28 cases)was 2.0±0.9mm.There was a significant difference in ATT between the two groups(p<0.001).Demographic parameters,reconstructed ligament diameter,X-ray evaluation(posterior tibial slope,joint degeneration),clinical function scores(Lysholm,Tegner,IKDC subjective scores,KOOS series scores,KOS-ADL)were not significantly different between the tension group and the relaxation group(p>0.05).(2)The three-dimensional kinematic stability of ACLR subjects in low-demand motion tasks and the influence of ATT on it:In the sit-to-stand task,the reconstructed knee had increased external tibial rotation and proximal tibial translation(p<0.05),and decreased anterior tibial translation(p<0.05);while the reconstructed knee had increased knee flexion during the mid-to-terminal standing phase(p=0.007),decreased tibial anterior translation at the end of the swing phase(p=0.047),and decreased range of motion(varus-valgus,internal-external tibial rotation,flexion-extension,anterior-posterior tibial translation)(p< 0.05).In the tense group,external tibial rotation increased(p<0.05),anterior tibial translation decreased(p<0.05),the knee flexion angle increased in the standing phase and swing phase(p<0.05),and the range of motion(adductionabduction,internal-external tibial rotation,flexion-extension,anterior-posterior tibial translation)decreased(p<0.05),while the relaxation group showed a smaller increase in external tibial rotation(p<0.05),smaller amplitude of anterior tibial translation decreased(p<0.05),an increase of proximal tibial translation increased(p<0.05),and a decrease of range of motion(varus-valgus,flexion-extension)(p<0.05).Study Part Ⅱ: ACLR Knee Kinematic Stability in High-demanding Motion Tasks and Differences between Different Anterior Tibial TranslationsMethod:Following the first part of the study,the three-dimensional kinematic analysis system of the knee joint was used to collect three-dimensional knee kinematics of the knee joints of ACLR patients in the states of crossover turning,cutting turning,running,cycling,climbing stairs,descending stairs,squatting(with both legs),and single slop jumping.Joint three-dimensional motion parameters.Results:Compared with low-demanding motion tasks,the reconstructed knee joint showed increased external tibial rotation(p<0.05),increased proximal tibial translation(p<0.05),and decreased anterior tibial translation(p<0.05),increased stance knee flexion angle(p<0.05),decreased range of motion(adduction-abduction,internal-external tibial rotation,flexion-extension,anterior-posterior tibial translation)(p<0.05),and also showed decreased knee flexion angle in standing phase(p=0.037,running),increased varus angle in standing phase(p<0.05,squatting),range of motion of medial-lateral tibial translation(p=0.047,descending stairs)in highdemanding motion tasks.The tense group showed increased stance phase knee flexion(p<0.05), decreased stance phase knee flexion(p=0.015,descending stairs),reduced anterior tibial translation,and increased external tibial rotation(p<0.05),smaller increased proximal tibial translation and increased medial tibial translation(p<0.05,squatting),decreased range of motion(adduction-abduction,internal-external tibial rotation,flexion-extension,anteriorposterior tibial translation)(p<0.05)in high-demanding motion tasks,while the relaxation group showed an increase in adduction angle(p<0.05),an increase in proximal tibial translation(p<0.05),a smaller reduction in anterior tibial translation(p<0.05),and a smaller increased stance knee flexion angle(p<0.05,crossover turn),a smaller increased external tibial rotation(p<0.05,squatting,single-leg jumping),a decrease knee flexion angle in the standing phase(p<0.05,running,descending stairs),a decrease knee flexion angle at the end of the crank angle cycle(p=0.004,cycling),and a smaller decrease range of motion(flexion-extension)(p<0.05).Study Part Ⅲ: ACLR Knee Kinematic Stability in Special-demanding Motion Tasks and Differences between Different Anterior Tibial TranslationsMethod:Following the second part of the study,the knee three-dimensional kinematics analysis system was used to collect the three-dimensional knee kinematic parameters of ACLR patients in the state of variable speed walkings and slope walkings.Results:The fast walking phase of variable speed walking can stimulate more features of motion instability: increased external tibial rotation(p<0.05)in the mid-to-late stance phase of the ACLR reconstructed knee joint(p<0.05),increased posterior tibial translation in the early stance phase(p=0.049),increased proximal tibial translation(p<0.05)in the early stance phase and the end phase of the swing phase and decreased range of motion(internal-external tibial rotation,flexion-extension,anterior-posterior tibial translation)(p<0.05).During downhill walking: increased external tibial rotation on the ACLR reconstruction side(p<0.05),increased knee flexion angle in the early stage of the stance phase and the end stage of the swing phase(p<0.05),and decreased anterior tibial translation(p<0.05),increased proximal tibial translation during stance and swing phases(p<0.05),decreased range of motion(adduction-abduction,internal-external tibial rotation,flexion-extension,anterior-posterior translation)(p<0.05);Uphill walking: increased external tibial rotation of the ACLR reconstruction side in stance phase(p<0.05),decreased knee flexion angle in stance phase and swing phase(p<0.05),no significant difference in anterior tibial translation(p>0.05),increased proximal tibial translation in the stance phase and the swing phase(p<0.05),and decreased range of motion(adductionabduction,internal-external tibial rotation,flexion-extension,anterior-posterior tibial translation)(p<0.05);in addition,no matter in the uphill or downhill process,the varus angle of the ACLR reconstructed knee joint was not significantly different from that of the uninjured knee joint,but there was a significant trend of increased varus angle.Tension group and relaxation group can significantly express similar movement instability characteristics in lowdemanding and high-demanding motion tasks in variable speed walking and slope walking,respectively.Conclusions:This study confirmed Hypothesis 1,that is,ACLR will show knee kinematic instability characteristics in different motion tasks,and there are knee kinematic differences among different motion tasks.There are increased adduction angle and increased proximal tibial translation,increased posterior tibial translation,increased/decreased knee flexion angle,increased external tibial rotation,and decreased range of motion(adduction-abduction,internalexternal tibial rotation,flexion-extension,anterior-posterior tibial translation)in the ACLR reconstructive knees.Overall,more kinematic instability features were shown during highdemanding motion tasks.However,combined with literature reports,the characteristics of ACLR kinematic instability are closely related to knee joint degeneration and re-injury.Corresponding treatment strategies still need to be adopted to improve ACLR motion instability,delay joint degeneration and reduce the rate of re-injury.This study confirmed hypothesis 2,that is,ATT can significantly affect the characteristics of ACLR subjects’ knee kinematic instability in motion tasks,and the mechanism may be related to the limitation of lateral femoral condyle motion by single-bundle anatomical ACLR surgery.When the ATT of the joint was small(tension group),the reconstructed sides showed a significant reduction in tibial anterior translation,an increase in knee flexion angle in stance phase,an increase in external tibial rotation,and a decrease in range of motion(adduction-abduction,internal-external tibial rotation,flexion-extension,anterior-posterior tibial translation);when the ATT of the knee joint was large(relaxation group),the knee joint on the reconstructed side of ACLR subjects could show a smaller reduction in anterior tibial translation,no significant difference/a decrease in stance knee flexion angle,no significant difference/ a slight increase in external tibial rotation,an increase in adduction angle,and increase in proximal tibial translation,and no significant difference/a slight decrease in range of motion.Overall,the tense group exhibited more knee kinematic instability features than the relaxed group in the study results.For ACLR surgery,if the operation restricts the lateral femoral condyle too tightly,that is,if the ATT difference between the affected side and the healthy side is too small,it may cause more knee joint kinematic instability.However,further research is required to detect the actual effects of the kinematic characteristics.This study confirmed Hypothesis 3,that is,variable speed walking and slope walking can be effectively used to reveal the characteristics of ACLR motion instability,and the effect of slope walking is more significant.Based on the fact that walking is a weight-bearing,easy,and simple functional action for patients to adapt,it can be easily implemented in clinical practice when combined with a treadmill.Variable speed walking and slope walking can be used as a choice in clinical application for detection or follow-up of knee kinematic instability in ACLR subjects.From the perspective of different requirements of motion tasks,this study reveals ACLR subjects’ kinematic instability characteristics,the possible cause mechanism of instability characteristics,and the possible routine application of clinical ACLR movement instability detection.It provides a theoretical and practical reference for the understanding of the characteristics of ACLR kinematic instability,the possibility of improving ACLR kinematic instability through surgical mechanisms,and the clinical application of routine detection of ACLR kinematic instability. |
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