Knee External Rotation Research Articles

Knee Kinetics in Baseball Hitting and Return to Play after ACL Reconstruction.

The purpose of this study was to describe the knee kinetics of baseball hitting, develop a tool to predict knee kinetics from easily obtainable measures, and to compare knee kinetics to other exercises along the rehabilitation continuum to determine a timeline for when hitting may resume after ACL reconstruction. Nineteen high school baseball athletes (16.3±0.8 yrs, 180.6±5.7 cm, 78.4±10.8 kg) participated. Participants took ten swings off a tee. Kinetic data were recorded using an electromagnetic tracking system. Data from swings with the top three exit velocities were averaged for analysis. Linear regressions were used to determine if predictors of height, mass, age and exit velocity could predict the following torques: bilateral knee net, extension, internal and external rotation, valgus and varus torque; and anterior force. Backwards regression models revealed independent variables could significantly predict front knee net, internal and external rotation, extension, and varus torque, and anterior force; and back knee net and valgus torque. Based on the kinetics of baseball hitting compared to those of rehabilitation exercises, if the involved knee is the front, we suggest tee hitting may be initiated at 13 weeks after ACL reconstruction. If the involved knee is the back, we suggest tee hitting may initiated at 17 weeks after ACL reconstruction.

Effect of Different Knee Braces in ACL-Deficient Patients.

Knee braces are often used during rehabilitation after ACL injury. There are two main concepts, rigid and soft braces, but studies comparing the two show conflicting results. Most studies used movement tasks with low translational or rotational loads and did not provide joint kinematics. Therefore, the purpose of this study was to investigate the influence of two different knee braces (rigid vs. soft) on knee joint kinematics in ACL-deficient patients compared to an unbraced control condition using two tasks (walking and 180° cutting) provoking knee movements in the frontal and transverse planes. 17 subjects with ACL-deficient knees participated in this study. 3D knee joint kinematics were recorded. To provoke frontal plane knee joint motion a laterally tilting plate was applied during a walking task. Both braces reduced the maximum valgus angle compared to the unbraced condition, stabilizing the knee joint against excessive valgus motion. Yet, no differences in peak abduction angle between the two braces were found. However, a significant extension deficit was observed with the rigid brace. Moreover, both braces increased transverse plane RoM and peak internal rotation angle, with the effects being significantly larger with the rigid brace. These effects have been associated with decreased knee stability and unphysiological cartilage loading. Therefore, the soft brace seems to be able to limit peak abduction with a lesser impact on physiological gait compared to the rigid brace. The cutting task was selected to provoke transverse plane knee movement and large external knee rotation was expected. However, none of the braces was able to reduce peak external knee rotation. Again, an increase in transverse plane RoM was observed with both braces. Based on these results, no brace outmatched the other in the second task. This study was the first attempt to clarify the effect of brace design for the stabilization of the knee joint during movements with frontal and transverse plane loading. However, to provide physicians and patients with a comprehensive guideline for brace usage, future studies will have to extent these findings to other daily or sportive movement tasks.

Clinical outcomes of kinematic alignment versus mechanical alignment in total knee arthroplasty: a systematic review.

Although mechanical alignment (MA) has traditionally been considered the gold standard, the optimal alignment strategy for total knee arthroplasty (TKA) is still debated.Kinematic alignment (KA) aims to restore native alignment by respecting the three axes of rotation of the knee and thereby producing knee motion more akin to the native knee.Designer surgeon case series and case control studies have demonstrated excellent subjective and objective clinical outcomes as well as survivorship for KA TKA with up to 10 years follow up, but these results have not been reproduced in high-quality randomized clinical trials.Gait analyses have demonstrated differences in parameters such as knee adduction, extension and external rotation moments, the relevance of which needs further evaluation.Objective improvements in soft tissue balance using KA have not been shown to result in improvements in patient-reported outcomes measures.Technologies that permit accurate reproduction of implant positioning and objective measurement of soft tissue balance, such as robotic-assisted TKA and compartmental pressure sensors, may play an important role in improving our understanding of the optimum alignment strategy and implant position.Cite this article: EFORT Open Rev 2020;5:486-497. DOI: 10.1302/2058-5241.5.190093

Field hockey sport-specific postures during unanticipated sidestepping: Implications for anterior cruciate ligament injury prevention

ABSTRACT Much research has investigated whole-body postures and associated knee joint loading during unanticipated sidestepping (UnSS). However, no research has considered sport-specific postures in field hockey. The purpose of this study was to investigate differences in trunk and lower limb angle and lower extremity joint moment waveforms during UnSS while holding a hockey stick in a flexed posture (HS-UnSS) and traditional UnSS. Additionally, we aimed to determine if differences in posture during HS-UnSS were associated with changes in knee joint moments. Twelve elite female field hockey athletes underwent 3D motion analysis during UnSS and HS-UnSS. Athletes increased trunk (0–100% of stance phase, hip (0–15%), knee (12–29%; 39–59%; 78–100%) and ankle (41–57%) flexion angles, and increased hip flexion (19–24%; 42–45%; 75–84%) and external rotation moments (75–80%) during HS-UnSS compared with UnSS (p < 0.05). Flexed postures observed during HS-UnSS did not influence knee flexion and valgus moments when compared with UnSS (p > 0.05), however knee external rotation moments reduced. Changes in trunk flexion were positively associated with peak knee internal rotation moments from UnSS to HS-UnSS (r = 0.779, p = 0.005). These findings indicate that field hockey players sidestep with significantly different techniques when holding a hockey stick, which should be considered in injury prevention training protocols.

Do Not Do this Case Report: Recurrence of Knee Flexion Contracture after Extension Osteotomy in Congenital Patellar Dislocation: The Importance of a Thorough Patient Evaluation

Background: Congenital patellar dislocation (CPD) is a rare disorder which presents with hypoplastic and irreducible patellae. It is accompanied by flexion contracture of the knee joint, genu valgum, and external tibial rotation. Case Report: A seven-year-old girl with CPD who was misdiagnosed as having cerebral palsy (CP) crouch gait and underwent distal femoral extension osteotomy (DFEO) without paying attention to the dislocated patellae, is presented. Recurrence ensued, and the patient was referred for further evaluation. After a second surgery to address the dislocated patellae, the flexion contracture and gait pattern improved significantly. Conclusion: The case underscores the importance of a systematic, thorough physical examination, without which uncommon diagnoses will be overlooked, exposing the patient to further morbidity and complications.

Disease-specific gait deviations in pediatric patients with X-linked hypophosphatemia

BackgroundX-linked hypophosphatemia (XLH) represents the most common genetic form of rickets featuring profound hypophosphatemia with associated skeletal and non-skeletal manifestations. Early onset gait disturbances contribute strongly to the burden of disease. However, no study has comprehensively characterized naturally occurring gait deviations in pediatric patients with XLH. Research questionsCan disease-specific gait deviations and potentially influencing factors be identified by gait analysis in non-surgically treated children with XLH? MethodsGait laboratory assessments of 12 pediatric patients with XLH without previous long bone surgery was retrospectively analyzed and compared to age-matched healthy controls. Radiologic and clinical parameters of XLH patients were correlated with kinematic gait variables and gait scores. ResultsReduced external knee rotation and increased external hip orientation was ubiquitous in children with XLH. Increased lateral trunk lean, or “waddling gait”, occurred in five children and was associated with varus knee deformities. Overall, children with XLH showed a reduced Gait Deviation Index (GDI) compared to controls. Radiologic and gait analysis revealed complex combined frontal and torsional deformity of the lower limbs as a common feature in XLH. Higher Body Mass Index (BMI) was associated with both lateral trunk lean and impaired GDI. SignificanceGait analysis is feasible to quantify gait deviations and lower limb deformities in pediatric patients with XLH. Specific gait characteristics including internal knee rotation and external hip rotation are common among patients with XLH and contribute to impaired gait scores. Our data suggest the use of gait and deformity data assessment as outcome parameters in future observational and interventional studies. Standardized assessment might contribute to targeted treatments to improve life quality in XLH patients.

Sex-specific Knee Biomechanics Associated With Patellofemoral Pain In Amateur Runners During Running

Patellofemoral Pain (PFP) is a common injury among runners. The mechanisms of sex differences associated with lower extremity biomechanics in PFP are still unclear. PURPOSE: To determine the differences in knee biomechanics between male and female amateur runners with PFP and without PFP in running task. Further, to determine the sex-specific biomechanical factors associated with the development of PFP. METHODS: 15 male and 10 female amateur runners aged 18 to 40 years with PFP were screened and enrolled in PFP group, 25 healthy amateur runners matched with the PFP group in sex, age, and running experience were recruited as control group. PFP group was tested running with and without knee pain (PFP with pain and PFP without pain groups), while control group performed one running test (running speed = 4.0 ± 0.3 m/s). Knee pain in PFP group was eliminated by decreasing the volume of running. Knee kinematics and kinetics during landing phase of running were reduced from reflective marker coordinates and ground reaction force data, as well as compared among groups and between sexes. RESULTS: Peak knee valgus angle of running in PFP group with pain (male: 3.2 ± 4.2°, female: 4.8 ± 4.9°, P = 0.001) and control group (male: 1.9 ± 2.7°, female: 3.8 ± 3.0°, P = 0.001) were significantly lower compared to PFP group without pain (male: 4.5 ± 4.3°, female: 7.9 ± 3.1°). Peak knee external rotation moment of running in PFP group with pain (male: 0.021 ± 0.008 BW × BH, female: 0.019 ± 0.006 BW × BH, P = 0.019) and control group (male: 0.020 ± 0.006 BW × BH, female: 0.017 ± 0.006 BW × BH, P = 0.001) were significantly lower compared to PFP group without pain (male: 0.024 ± 0.009 BW × BH, female: 0.022 ± 0.008 BW × BH). Peak knee flexion angle of running in PFP group without pain (48.8 ± 5.6°) was significantly greater compared to control group for male participants (46.0 ± 3.6°, P = 0.008). CONCLUSIONS: Decreased knee valgus angle and external rotation moment in running appeared to be compensations to avoid pain when amateur runners with PFP were running with pain, and increased knee valgus angle and external rotation moment might be biomechanical factors associated with the development of PFP. Increased knee flexion angle in running may be another critical biomechanical factor associated with the development of PFP for male amateur runners.

Calcaneal Eversion Affects Coupled Knee Rotation During Gait

It has been suggested that ankle motion (specifically, subtalar (ST) and tibiotalar (TT) joints) may contribute to knee pathologies such as patellofemoral pain syndrome. Yet, in-depth understanding of knee and ankle joint coupling remains elusive due to challenges in accurately measuring three dimensional (3D) bone motion in vivo. PURPOSE: To determine coupled knee and ankle kinematics during the weight-bearing phase of gait in healthy adults. METHODS: Dynamic biplane radiography was used to measure coupled kinematics during walking in 12 ankles and knees from six healthy volunteers (ages 18 - 35 yrs.). Synchronized biplane radiographs were collected at 100hz over the entire support phase of gait, from foot-strike through toe-off. Next, CT scans were acquired and subject-specific models of each bone were generated and used to track the 3D bone motion during each trial using a validated technique with sub-millimeter and sub-degree accuracy. Six degrees of freedom ankle and knee kinematics were normalized to percent stance and divided into loading, mid-stance, and push-off phases. The coupled outcome kinematics were 1) ST inversion and knee internal rotation, and 2) TT dorsiflexion and knee flexion. Associations between ankle and knee coupled kinematics were evaluated using Spearman’s rho with significance set at p<0.05. RESULTS: During midstance, the knee internal rotation always accompanied ST inversion while external rotation accompanied eversion (R2=0.63, p=0.085) (Figure 1). During mid-stance TT plantar flexion always occurred with knee extension (R2=0.12, p=0.71). CONCLUSIONS: In healthy knees, ST inversion/eversion appears to play a role in knee internal rotation during the mid-stance of gait. This finding suggests assessing coupled motion between the knee and ankle may be beneficial for evaluating single joint pathology. This work was supported by NIH Grant: R44HD066831.Figure 1: Chart showing coupled ST inversion and knee external rotation during mid stance of gait.

Breast Support Alters Knee Joint Biomechanics During A Landing Task.

Females have a greater rate of traumatic knee injuries than male athletes. Trunk position has been shown to affect knee joint biomechanics during a landing task. Given the position of breast tissue, insufficiently supported breasts may also alter knee joint biomechanics. However, no previous research has investigated the effect of breast tissue or support on knee joint biomechanics during landing. PURPOSE: to determine the effect of breast support on knee and hip joint kinetics during a landing task. METHODS: Fifteen female athletes performed five step-off landings from a height of 40 cm in each of three bra support conditions: control (CON), low support (LOW) and high support (HIGH). 3D kinematics and ground reaction forces (GRFs) were simultaneously recorded using a 9-camera motion capture system (240 Hz,) and pair of force platforms (1200 Hz,)..) was used to calculate knee and hip joint angles and moments. Custom software (was used to determine peak joint angles and moments. Repeated measures ANOVAs with Tukey’s post-hoc analyses were used to compare mean knee and hip joint kinetics. RESULTS: No differences in peak knee abduction moments were observed, though peak knee external rotation moments were smaller in the LOW compared to CON (p = 0.007) and HIGH conditions (p = 0.013). No differences were observed between CON and HIGH (p = 0.423). No differences were observed in peak hip abduction moment or peak hip external rotation moment. CONCLUSIONS: These findings indicate that knee joint biomechanics during a landing task are affected by breast support. The current study did not address the role of trunk orientation or differences in breast size amongst participants. Future research should address the role of breast motion on trunk kinematics and kinetics.Table 1: Mean knee and hip joint moments in the CON, LOW and HIGH support conditions.

Walking Biomechanics Associated With Patellofemoral Pain In Sedentary And Active Emerging Adult Women

About 50% of emerging adults do not meet the national physical activity recommendations. Risk of injury, like patellofemoral pain (PFP) during walking, may be a barrier to meeting the physical activity recommendations for sedentary emerging adults. PURPOSE: To determine if sedentary emerging adult women had walking biomechanics related to PFP compared to active emerging adult women. METHODS: As part of a larger study, 26 (12 sedentary, 14 active) emerging adult women (age:22(3) years; height: 1.58(0.08) m; mass: 58.4(8.7) kg) participated in the study. Anatomical and tracking retro-reflective markers were placed on body segments to record movement. Participants completed 5 good walking trials at 1.4 m/s (± 5%). Three-dimensional gait analysis was performed using motion capture sampling at 200 Hz and force platforms sampling at 1000Hz. Joint angles were determined using the joint coordinate system and moment was determined using inverse dynamics. The variables of interest were peak knee flexion angle, peak internal knee extensor moment (PKEM), knee abduction and external rotation angles at PKEM, and hip adduction and internal rotation angles at PKEM. Independent t-tests compared variables between sedentary and active emerging adult women. Effect sizes (d) were calculated for each variable. RESULTS: Knee external rotation angle at PKEM was significantly larger in sedentary compared to active emerging adult women (Table 1). There were no other significant differences between the sedentary and active groups for the remaining variables of interest. CONCLUSION: A larger knee external rotation angle at PKEM suggests higher pressure on the lateral patella in the sedentary versus active group. According to the pathomechanical model for PFP, high lateral pressure and associated high cartilage stress is a mechanism for the develop of PFP. Therefore, sedentary women may be more at risk for developing PFP during walking for exercise compared to active women.Table 1:: hip and knee biomechanics during walking in sedentary and active emerging adult women

Relationship Between Jump-Landing Kinematics and Lower Extremity Overuse Injuries in Physically Active Populations: A Systematic Review and Meta-Analysis.

Lower extremity overuse injuries are common in athletes participating in sports with repeated bouts of landing manoeuvres. Biomechanical alterations during landing may be associated with these types of injuries. The objective of this systematic review with meta-analysis was to summarise and determine the relationship between kinematic alterations during a landing task and the development of lower extremity overuse injuries in physically active populations. PubMed, Embase, Web of Science, CINAHL, and SPORTDiscus were consulted up to and including February 2020. Cohort, cross-sectional or case-control studies were included if they investigated the relationship between three-dimensional (3D) landing kinematics in physically active populations and either new incidence or a history of lower extremity overuse injuries. Twenty-three studies that investigated 3D landing kinematics in subjects with either patellar tendinopathy (PT), patellofemoral pain (PFP), exertional medial tibial pain (EMTP) or groin overuse injury met the inclusion criteria. Based on this systematic review, there is evidence for decreased knee flexion range of motion (ROM) and increased knee abduction ROM during landing as risk factors for PFP. For PT, risk factors are poorly understood. Furthermore, the meta-analysis demonstrated significantly greater hip adduction at initial contact (IC) (p = 0.02), greater knee internal rotation at IC (p < 0.001), greater peak knee external rotation (p = 0.05) and less ankle dorsiflexion at peak vertical ground reaction force (vGRF) (p = 0.05) in subjects with knee overuse injuries compared to healthy controls. There is evidence of increased trunk, hip and knee transversal ROM as risk factors for EMTP. Groin injuries are associated with greater pelvic and hip frontal and transversal plane ROM in the injured group compared to the healthy controls. The results of this systematic review and meta-analysis provide preliminary evidence for impaired landing kinematics associated with lower extremity overuse injuries. Excessive frontal and transversal plane movements during landing manoeuvres might increase impact and tensile forces resulting in lower extremity overuse injuries. This systematic review was registered in the PROSPERO international prospective register of systematic reviews (ID = CRD42019135602).

Dancers' Joint Strategies for Achieving Turnout in Low and High Friction Conditions.

Dancing with legs externally rotated (turnout) is a fundamental element of ballet technique. A reliance on floor friction to achieve turnout may contribute toward the high injury rate in dancers. Joint strategies used by dancers in high and low friction turnout conditions are not well understood. To quantify the lower limb and lumbar spine joint strategies used by female pre-professional dancers to achieve turnout in low-friction (rotation discs) and high-friction (functional and forced) conditions. Twenty-three pre-professional female dancers participated in the study. A 12-camera motion analysis system collected hip and knee external rotation (ER), ankle abduction, and lumbar extension angles in three turnout conditions and passive hip ER range of motion angles. Repeated measures ANOVA analysed the differences between joint angles, maximum turnout angle (foot relative to pelvis), and available hip ER. Dancers demonstrated lower knee ER (18.5±4.8°) and ankle abduction (6.0±7.7°) angles during low-friction turnout compared to higher friction conditions (p<0.05). Dancers utilised between 70-83% of available hip ER within all conditions. Low-friction turnout demonstrated greater hip ER contribution within maximum turnout (43%) compared to higher friction conditions. Dancers demonstrated greater lumbar extension angles in low-friction turnout compared to higher friction conditions (p<0.05). Further hip ER strength training is required to promote greater hip ER range within the position. Rotation discs may be a valuable training tool as dancers demonstrated greater hip ER utilisation with less knee ER and ankle abduction; however, this position did promote undesirable lumbar extension.

Prediction of Knee Kinematics at the Time of Noncontact Anterior Cruciate Ligament Injuries Based on the Bone Bruises.

Biomechanical risk factors associated with the alignment and position of the knee for anterior cruciate ligament (ACL) injury are still not conclusive. As bone bruises identified on magnetic resonance imaging (MRI) following acute ACL injury could represent the impact footprint at the time of injury. To improve understanding of the ACL injury mechanism, we aimed to determine the knee kinematics during ACL injury based on the bone bruises. Knee MRI scans of patients who underwent acute noncontact ACL injuries were acquired. Numerical optimization was used to match the bone bruises of the femur and tibia and predict the knee positions during injury. Knee angles were compared between MRI measured position and predicted position. The knee flexion, abduction, and external tibial rotation angles were significantly greater in the predicted position than that in MRI measured position. Relative to MRI measured position, patients had a mean of 34.3mm of anterior tibial translation, 4.0mm of lateral tibial translation, and 16.0mm superior tibial translation in the predicted position. The results suggest that knee valgus and external tibial rotation accompanied by knee flexion are high-risk movement pattern for ACL injury in patients with lateral compartment bone bruising in conjunction with ACL injury.

INFLUENCE OF LOWER EXTREMITY STATIC ALIGNMENT ON DYNAMIC KNEE VALGUS IN ADOLESCENTS FOLLOWING ACL RECONSTRUCTION

Background:Dynamic limb valgus, particularly high knee abduction moments, are a known risk factor for anterior cruciate ligament (ACL) injury. High knee abduction moments may result from poor static anatomic limb alignment, faulty biomechanics, or a combination of both. The distinction is important because anatomic limb alignment is difficult to change, while dynamic factors can be addressed through neuromuscular or biomechanical training.Hypothesis/Purpose:This study assessed the influence of static (lower extremity anatomic alignment) and dynamic (kinematic and kinetic) factors on external knee abduction moments during side-step cutting in uninjured adolescent athletes.Methods:This retrospective study included 43 adolescents with recent unilateral ACL reconstruction (mean age 15.3 years, SD 2.0, range 10-21; 17/43 female; 3-12 months post-surgery, mean 6.5, SD 2.1). Frontal plane hip to ankle imaging (EOS) was used to measure mechanical axis deviation (perpendicular distance from the center of the femoral condyles to the mechanical axis line connecting the center of the femoral head to the center of the talar dome) and tibial-femoral angle. Femoral anteversion was measured during physical examination. 3D motion capture provided lower extremity kinematics and kinetics during quiet standing and during the loading phase (initial contact to peak knee flexion) of an anticipated 45° side-step cut, with 2-3 trials per limb averaged for analysis. Relationships among imaging, static motion capture, and dynamic motion capture measures were investigated using correlation, and backward stepwise linear regression was used to evaluate potential predictors of average dynamic knee abduction moment.Results:Dynamic knee abduction moment was best predicted by a combination of dynamic measures: knee and hip abduction, external knee rotation, lateral trunk lean towards the planting foot, and ankle inversion during cutting (Table 1.1). Although EOS frontal plane tibial-femoral angle was correlated with dynamic knee abduction moment (r=0.24, p=0.02), no static/anatomic variables entered the model once the dynamic measures were included.Conclusion:Knee abduction moments during side-step cutting were related to dynamic factors reflecting frontal plane trunk, hip, knee, and ankle motion, as well as external knee rotation. Static (anatomic) lower limb alignment did not influence knee abduction moments once these dynamic factors were considered. Knee abduction moments and ACL injury risk are therefore not dictated by anatomic alignment and can be altered through neuromuscular/biomechanical training.Table 1.1.Multivariable prediction of average knee abduction moment during cutting (R2=0.69) βPDynamic ankle eversion-0.35<0.001Dynamic knee external rotation0.69<0.001Dynamic hip abduction0.180.004Dynamic trunk contralateral lean0.170.007Dynamic knee abduction0.39<0.001

Differences in anterior cruciate ligament injury risk factors between female dancers and female soccer players during single- and double-leg landing

The purpose of this study was to compare anterior cruciate ligament (ACL) injury risk factors between female dancers and female soccer players during single- and double-leg drop landing vertical jump tasks. Fifteen elite female soccer players and 45 professional female dancers (15 ballet, 15 modern, and 15 Korean dancers) were recruited to participate in this study. ACL injury risk factors were obtained from motion and ground reaction force data. Two-way repeated measure of analyses of variance (participant groups and landing tasks, 4 × 2) were used. The female dancers landed with a significantly lower trunk flexion, trunk external rotation, knee external rotation, and knee valgus moment than the female soccer players. In addition, the single-leg drop landing task demonstrated higher trunk external rotation and knee valgus moment than the double-leg drop landing vertical jump task. The female dancers had lower ACL injury risk factors than the female soccer players during landing tasks. The single-leg drop landing task is statistically correlated with ACL injury risk factors compared with double-leg drop landing vertical jump task in all groups. Le but de cette étude était de comparer les facteurs de risque de lésion du ligament croisé antérieur (LCA) entre les danseuses et les footballeuses lors de tâches de saut vertical à une ou deux jambes. Quinze joueuses de football d’élite et 45 danseuses professionnelles (15 danseuses, 15 danseuses modernes et 15 danseuses coréennes) ont été recrutées pour participer à cette étude. Les facteurs de risque de lésion du LCA ont été obtenus à partir des données de force de réaction au sol et au mouvement. Des mesures répétées d’analyses de variance (groupes de participants et tâches d’atterrissage, 4 × 2) ont été utilisées. Les danseuses ont atterri avec une flexion du tronc, une rotation externe du tronc, une rotation externe du genou et un valgus du genou significativement plus faible que les footballeuses. En outre, la tâche d’atterrissage en chute libre sur une jambe a démontré une rotation externe du tronc et un moment valgus au genou plus élevé que la tâche de saut vertical en atterrissage en chute double. Les femmes danseuses présentaient des facteurs de risque de lésion du LCA plus faibles que les footballeuses lors des tâches d’atterrissage. La tâche d’atterrissage en chute libre sur une jambe est statistiquement corrélée aux facteurs de risque de lésion du LCA par rapport à la tâche de saut vertical en atterrissage en chute double pour tous les groupes.

Weight-bearing status affects in vivo kinematics following mobile-bearing unicompartmental knee arthroplasty.

The effects of weight bearing (WB) on knee kinematics following mobile-bearing unicompartmental knee arthroplasty (UKA) remain unknown. The purpose of this study was to clarify the effects of WB on in vivo kinematics of mobile-bearing UKA during high knee flexion activities. The kinematics of UKA were evaluated under fluoroscopy during squatting (WB) and active-assisted knee flexion (non-weight bearing, NWB). Range of motion, femoral axis rotation relative to the tibia, anteroposterior (AP) translation of the medial and lateral sides, and kinematic pathway were measured. There were no differences in knee flexion range and external rotation of the femur in each flexion angle between the WB conditions. The amount of femoral external rotation between minimum flexion and 60° of flexion during WB was significantly larger than that during NWB, and that between 60° and 130° of flexion during NWB was significantly larger than that during WB. There were no differences in medial AP translation of the femur in each flexion angle between the WB conditions. However, on the lateral side, posterior translation of 52.9 ± 12.7% was observed between minimum flexion and 130° of flexion during WB. During NWB, there was no significant translation between minimum flexion and 60° of flexion; beyond 60° of flexion, posterior translation was 41.6 ± 8.7%. Between 20° and 80° of flexion, the lateral side in WB was located more posteriorly than in NWB (p < 0.05). Mobile-bearing UKA has good anterior stability throughout the range of knee flexion. WB status affects the in vivo kinematics following mobile-bearing UKA. III.

Inertial motion capture validation of 3D knee kinematics at various gait speed on the treadmill with a double-pose calibration

BackgroundInertial motion capture (IMC) is rapidly gaining in popularity to evaluate gait in clinical settings. Previous examinations of IMC knee kinematics were often limited to the sagittal plane and IMC calibration has not been thoroughly investigated. Research questionThe objective was to validate IMC 3D knee kinematics calibrated with a double-pose during gait with reference to optical motion capture (OMC). The hypotheses are that IMC can estimate adequately knee kinematics and that both systems will detect similarly the changes with gait speed. MethodsTwenty-four healthy participants walked on the treadmill at gait speed of 0.6, 0.8, 1.0 and 1.2 m/s. Knee kinematics were obtained simultaneously with two magnetic and inertial measurement units and passive markers fixed on the KneeKG system. OMC was calibrated with a functional anatomical approach and the IMC with a double-pose. ResultsRoot mean square differences of the two systems yielded 3-6° for knee flexion, adduction and external rotation. Knee kinematics were more similar during the stance phase than the swing phase. Gait speed showed a significant progressive effect on the three knee angles that was similarly detected by the two systems. SignificanceIMC 3D knee kinematics can be obtained independently with a simple calibration and only two magnetic and inertial measurement units at an acceptable level of error especially during stance.

Kinematic, kinetic and electromyographic differences between young adults with and without chronic ankle instability during walking

The objective of this study was to quantify the kinematic, kinetic and electromyography differences between individuals with and without chronic ankle instability (CAI) during comfortable (CW) and fast (FW) walking. Twenty-one individuals with CAI and 21 healthy controls were recruited to walk at CW and FW speeds. The dependent variables were gluteus medius, vastus lateralis, gastrocnemius lateralis, gastrocnemius medialis, peroneus longus and tibialis anterior muscles mean activity, ankle and knee angles and moments. Kinematic, kinetic and electromyography variables were compared between groups with a one-dimensional statistical non-parametric mapping analysis. The CAI group exhibited no significant difference for ankle angles and moments compared to the control group. However, the CAI group showed less external knee rotation from 56 to 100% (CW) and 51 to 98% (FW) and more knee abduction moment from 1 to 6% and 7 to 9% (CW) and 1 to 2% (FW) of the stance phase. Less gluteus medius muscle activity was also observed from 6 to 9% and 99 to 100% (CW) of the stance phase for the CAI group. These results suggest proximal biomechanical compensations and will help better understand the underlying deficits associated with CAI. They also indicate that regardless of walking speeds, individuals with CAI exhibit similar differences compared to healthy participants.

Effects of Foot Rotation on ACL Injury Risk Variables During Drop Landing

Landing is considered a “high-risk” movement for anterior cruciate ligament (ACL) injuries. Foot progression angle (FPA) during landing has been shown to influence hip, knee, and ankle mechanics. The purpose of this study was to compare five FPA conditions during drop landings between males and females. Twenty males and females were tested using five FPA conditions: self-selected, toe-in 15°, toe-in 30°, toe-out 15°, and toe-out 30°. Right hip, knee, and ankle joint kinematics and kinetics were collected using a 12-camera motion capture system and two force plates. Five successful trials were collected and compared between FPA conditions. The main effect for FPA condition was statistically different for initial contact hip flexion, hip abduction, hip internal rotation, knee flexion, knee abduction, knee external rotation, and ankle inversion angles compared to self-selected FPA at P < 0.05. Peak hip extension, hip abduction, knee adduction, knee internal rotation, ankle plantar flexion, and ankle inversion moments were also found to be statistically significant (P < 0.05). Overall, females experienced greater initial knee abduction angle (P = 0.028), hip abduction moment (P = 0.006), knee extension moment (P = 0.033), and knee internal rotation moment (P = 0.044), regardless of FPA condition. Males experienced greater initial contact hip abduction angle (P = 0.0017), regardless of FPA condition. The results suggest that landing with large toe-in FPA will increase the magnitude of ACL injury risk variables, and females demonstrated a greater magnitude in these variables compared to males. Injury prevention programs may seek to target FPA as part of training activities to avoid large FPA toe-in landings.

Which of the five classical ballet positions is the most demanding for the dancer’s body? An electromyography-based study to determine muscular activity

The study aimed to determine which of the five classical ballet positions is the most demanding regarding muscular activity, values of external rotation in the hip joints, angular values of foot progression as well as the inclination (tilt) of the pelvis in the sagittal plane. In this cross-sectional study, 14 female pre-professional ballet dancers (aged 11-16) participated. Participants were tasked with the sequential adoption of five classical ballet positions (CP1-CP5). The electromyographic activity of the muscles of the trunk and the lower limb was recorded with surface electrodes. Kinematic data including hip and knee external rotation, foot progression angle and pelvic tilt were collected using a motion capture system. Symmetric positions CP1 and CP2 were not as demanding as asymmetric CP3-CP5. Higher values of hip and foot external rotation without greater muscular effort in CP2 than CP1 was noticed. Considering asymmetric positions, CP3 did not trigger a greater activity of hip or foot muscular groups than CP4 and CP5. CP4 was characterised by the greatest pelvic anterior tilt and the lowest activity of GM in the forward lower limb. In CP5, forward lower limb entailed a higher activity of muscles supporting the foot than in the remaining positions. In terms of biomechanics, the most demanding classical ballet position in pre-professional dancers is CP4, followed by CP5, CP3, CP1 and CP2. This finding can be applied in educational methodology of dancers, figure skaters, synchronized swimmers, acrobatic gymnasts, rhythmic gymnasts or cheerleaders.