Larger Knee Flexion Angles Research Articles

Hamstrings and Quadriceps Weaknesses Following Anterior Cruciate Ligament Reconstruction Persist Up to 6 Months After Return-to-Sport: An Angle-specific Strength Analysis.

Hamstrings and quadriceps strength recovery and restoration of the hamstrings-to-quadriceps ratio (H/Q ratio) is a major concern after anterior cruciate ligament reconstruction (ACLR). Recently, moment-angle profiles and angle-specific H/Q ratios are receiving increasing interest. The first objective of this study was to investigate moment-angle profiles and angle-specific H/Q ratio profiles in athletes with ACLR at the time of RTS. The second objective of this study was to assess whether strength asymmetries identified at the time of RTS, persist after six months. Case-Control study. Twenty athletes who had undergone ACLR performed isokinetic strength tests for concentric knee flexion and extension (60°/s) at RTS, and three and six months later. Twenty controls were tested once. T-tests were used to compare strength differences between 1) ACLR athletes and controls and 2) the injured and uninjured leg of the ACLR athletes. Finally, to assess strength deficits over time, two-way ANOVAs were used. Angle-specific analyses and peak moments showed lower hamstrings strength in the injured leg of ACLR athletes compared to their uninjured leg at RTS. Furthermore, angle-specific analyses showed a lower hamstrings strength and H/Q ratio in the injured leg compared to controls at larger knee flexion angles. The latter deficit was not identified with a peak-based analysis. The asymmetries identified at RTS did not change over the six months following RTS. Athletes with ACLR show strength deficits and asymmetries that persist even six months after RTS. As some asymmetries may go undetected by peak-based analyses, angle-specific analyses are recommended. Level 3b.

The effect of functional calibration methods on gait kinematics in adolescents with idiopathic rotational deformity of the femur

BackgroundDue to anatomical deviations, assumptions of the conventional calibration method for gait analysis may be violated in individuals with rotational deformities of the femur. Functional calibration methods were compared with conventional methods in this group for 1) localization of the hip joint center and orientation of the knee axis, and 2) gait kinematics. MethodsTwenty-four adolescents with idiopathic rotational deformity of the femur underwent gait analysis and a CT scan. During standing, distance between hip joint centers and knee axis orientation were compared between calibration methods, with CT serving as reference for hip joint center estimation. Gait kinematics were compared using statistical parametric mapping. FindingsThe conventional calibration method estimated the hip joint center closer to the CT reference (4±12 mm more lateral) than the functional calibration method (26 ± 20 mm more lateral). Orientation of the knee joint axis was 2.6° less internal in the functional calibration method. During gait, statistical parametric mapping revealed significantly more hip flexion, less external hip rotation during the swing phase, less knee varus-valgus motion, and larger knee flexion angles when applying the functional method. InterpretationFunctional calibration methods were less accurate in determining the hip joint center location than the conventional calibration method and resulted in a knee joint axis that was less internally rotated. Importantly, there was less knee joint angle crosstalk during gait when using the functional method. Although differences between methods on gait kinematics were within clinically acceptable limits for the sagittal plane, relatively larger differences on transversal hip kinematics may hold clinical importance.

Effect of different landing actions on knee joint biomechanics of female college athletes: Based on opensim simulation.

Background: The anterior cruciate ligament (ACL) is one of the most injurious parts of the knee in the biomechanical environment during landing actions. The purpose of this study was to compare the lower limb differences in movement patterns, muscle forces and ACL forces during drop landing (DL), drop vertical jump (DVJ) and forward vertical jump (FVJ). Methods: Eleven basketball and volleyball female college athletes (Division II and I) were recruited. Landing actions of DL, DVJ and FVJ, kinematics and dynamics data were collected synchronously using a motion capture system. OpenSim was used to calculate the ACL load, knee joint angle and moment, and muscle force. Results: At initial contact, different landing movements influenced knee flexion angle; DL action was significantly less than FVJ action (p = 0.046). Different landing actions affected quadriceps femoris forces; FVJ was significantly greater than DL and DVJ actions (p = 0.002 and p = 0.037, respectively). However, different landing movements had no significant effects on other variables (knee extension moment, knee valgus angle and moment, hamstring and gastrocnemius muscle forces, and ACL forces) (p > 0.050). Conclusion: There was no significant difference in the knee valgus, knee valgus moment, and the ACL forces between the three landing actions. However, knee flexion angle, knee extension moments sagittal factors, and quadriceps and gastrocnemius forces are critical factors for ACL injury. The DL action had a significantly smaller knee flexion angle, which may increase the risk of ACL injury, and not recommended to assess the risk of ACL injuries. The FVJ action had a larger knee flexion angle and higher quadriceps femoris forces that were more in line with daily training and competition needs. Therefore, it is recommended to use FVJ action in future studies on risk assessment of ACL injuries and injury prevention in female college athletes.

Uncertainty in Muscle-Tendon Parameters can Greatly Influence the Accuracy of Knee Contact Force Estimates of Musculoskeletal Models.

Understanding the sources of error is critical before models of the musculoskeletal system can be usefully translated. Using in vivo measured tibiofemoral forces, the impact of uncertainty in muscle–tendon parameters on the accuracy of knee contact force estimates of a generic musculoskeletal model was investigated following a probabilistic approach. Population variability was introduced to the routine musculoskeletal modeling framework by perturbing input parameters of the lower limb muscles around their baseline values. Using ground reaction force and skin marker trajectory data collected from six subjects performing body-weight squat, the knee contact force was calculated for the perturbed models. The combined impact of input uncertainties resulted in a considerable variation in the knee contact force estimates (up to 2.1 BW change in the predicted force), especially at larger knee flexion angles, hence explaining up to 70% of the simulation error. Although individual muscle groups exhibited different contributions to the overall error, variation in the maximum isometric force and pathway of the muscles showed the highest impacts on the model outcomes. Importantly, this study highlights parameters that should be personalized in order to achieve the best possible predictions when using generic musculoskeletal models for activities involving deep knee flexion.

Estimation of Tibiofemoral and Patellofemoral Joint Forces during Squatting and Kneeling

This study examined the differences of knee joint forces between lowering to, or rising from squat, and typical final postures of squatting and kneeling. A biomechanical model of the lower limb was configured considering large knee flexion angles, multiple floor contact points, and the soft tissue contact between the thigh and calf. Inverse dynamics were used to determine muscle and compressive joint forces in the tibiofemoral and patellofemoral joints. Data were obtained from a group of 13 male subjects by means of 3D motion capturing, two force plates, a pressure-sensitive pad, and electromyography. During lowering into the kneeling/squatting positions and rising from them, the model exhibited the anticipated high maximum forces of 2.6 ± 0.39 body weight (BW) and 3.4 ± 0.56 BW in the tibiofemoral and patellofemoral joints. Upon attainment of the static terminal squatting and kneeling positions, the forces fell considerably, remaining within a range of between 0.5 and 0.7 BW for the tibiofemoral joint and 0.9 to 1.1 BW for the patellofemoral joint. The differences of the knee joint forces between the final postures of squatting and kneeling remained on average below 0.25 BW and were significant only for the tibiofemoral joint force.

Effects of Video Task With a High-Level Exercise Illustration on Knee Movements in Male Volleyball Spike Jump

Hazardous knee biomechanics, such as excessive knee affordance link with injuries in volleyball spike jumps (SPJs) and can be reconfigured by the enhancement of internal focus. The study aimed to explore the effects of video tasks illustrating a high-level SPJ on knee movement in the volleyball SPJ with 15 elite male volleyball athletes. This study investigated the knee movements in sagittal, coronal, and transverse planes before and after the video task in SPJ using one-dimensional statistical parametric mapping (SPM 1D) and discrete statistics. The SPM 1D indicated a larger knee flexion angle (31.17–73.19%, t = 2.611, and p = 0.012), increased knee flexion moment (19.72–21.38%, t = 0.029, and p = 0.029), and increased knee adduction angular velocity (49.07–62.64%, t = 3.148, and p = 0.004) after video task; alternatively, smaller knee external rotation angular velocity (45.85–49.96%, t = 5.199, and p = 0.017) and vertical ground reaction (vGRF) (3.13–5.94%, t = 4.096, and p = 0.014; 19.83–21.97%, t = 4.096, and p = 0.024) were found after the task. With discrete value statistics, the video task increased the peak of knee flexion angle while decreased the peak of extension moment, flexion moment, abduction moment, external moment, the first peak vGRF, and related loading rate.Conclusions: The results indicate that knee biomechanics in volleyball SPJ positively influenced by the video task. The task has the athletes control the knee movements more actively and improves the original hazardous movement strategies. Therefore, the video task presumably can abate the occurrence of knee injuries in volleyball SPJ. Further validation especially in the exercise effect is needed in the future.

Impact of parity on biomechanical risk factors for knee OA initiation

BackgroundWomen are twice as likely as men to develop knee osteoarthritis (OA), and with it experience greater losses of physical function and disability. A change in the mechanical environment of the joint is a key initiating factor for knee OA. Differences in morphology, joint injury risk, and hormonal shifts in mid-life are often considered factors which increase OA risk for women. Pregnancy, a time of significant hormonal, morphological, and biomechanical change, has received comparably less attention. If morphological and biomechanical changes persist postpartum, this could increase OA risk for parous (childbearing) women. Research questionAre lower limb gait mechanics different between healthy nulliparous (non-childbearing) and parous (childbearing) women? MethodsTwenty-eight self-reported not pregnant female participants (14 parous, 14 nulliparous) were recruited for the study. Nulliparous participants had never given birth to a child. Parous participants had given birth to at least one full-term infant (37–42 weeks) without complications between one to five years before data collection. Motion capture of participants’ preferred, fast, and set (1.4 m/s) walking speeds was conducted. Repeated measures ANOVA were performed to test for significant group differences in joint kinematics and kinetics. ResultsThere was a significant main effect of group indicating a larger knee flexion angle at toe off (p = 0.0002), smaller knee extension moment at heel strike (p = 0.0006), smaller first peak knee flexion moment (p = 0.040), and smaller peak hip adduction moment for the parous group compared to the nulliparous group (p = 0.003). Static Q-angle did not differ between groups. SignificanceAlteration in mechanics from the habitual loading pattern are thought to increase risk of OA. Smaller knee moments in post-partum women could alter the mechanical stimulus to cartilage, and should be investigated in conjunction with cartilage health measures to determine the link with OA initiation.

Effects of knee flexion angles in supine bridge exercise on trunk and pelvic muscle activity

ABSTRACT This study investigated the activity of surface electromyography (sEMG) on trunk and pelvic muscles during supine bridge exercise (SBE) with different knee flexion angles. Twenty-five physically active males participated in this study. Subjects received maximum voluntary isometric contraction (MVIC) tests followed by four SBEs with different knee flexion angles (40°, 60°, 90° and 120°) in random. sEMG activities of rectus abdominis (RA), erector spinae (ER), gluteus medius (GMed), superior gluteus maximus (SGMax), inferior gluteus maximus (IGMax), biceps femoris (BF) long head, and the ratio of SGMax/BF and IGMax/BF on the dominant side were measured. Non-clinical magnitude-based inference was performed to compare the effect. The results indicated a substantial change of muscle activity, especially between SBE with 40° and 120° knee flexion. With respect to ER and BF, moderate effect (−0.70 ± 0.17) and extremely large effect (−4.78 ± 0.51) were recorded, whereas very large effect for SGMax/BF (2.68 ± 0.23) and IGMax/BF (2.95 ± 0.26) was observed, respectively. Both ER and BF worked better with smaller knee flexion angles (40° > 60° > 90° > 120°), while SGMax and IGMax were more favourable to SBE with large knee flexion angles (90° = 120° > 60° > 40°).

Biomechanical effects following footstrike pattern modification using wearable sensors

ObjectivesThis study sought to examine the biomechanical effects of an in-field sensor-based gait retraining program targeting footstrike pattern modification during level running, uphill running and downhill running. DesignQuasi-experimental design. MethodsSixteen habitual rearfoot strikers were recruited. All participants underwent a baseline evaluation on an instrumented treadmill at their preferred running speeds on three slope settings. Participants were then instructed to modify their footstrike pattern from rearfoot to non-rearfoot strike with real-time audio biofeedback in an 8-session in-field gait retraining program. A reassessment was conducted to evaluate the post-training biomechanical effects. Footstrike pattern, footstrike angle, vertical instantaneous loading rate (VILR), stride length, cadence, and knee flexion angle at initial contact were measured and compared. ResultsNo significant interaction was found between training and slope conditions for all tested variables. Significant main effects were observed for gait retraining (p-values≤0.02) and slopes (p-values≤0.01). After gait retraining, 75% of the participants modified their footstrike pattern during level running, but effects of footstrike pattern modification were inconsistent between slopes. During level running, participants exhibited a smaller footstrike angle (p≤0.01), reduced VILR (p≤0.01) and a larger knee flexion angle (p=0.01). Similar effects were found during uphill running, together with a shorter stride length (p=0.01) and an increased cadence (p≤0.01). However, during downhill running, no significant change in VILR was found (p=0.16), despite differences found in other biomechanical measurements (p-values=0.02–0.05). ConclusionAn 8-session in-field gait retraining program was effective in modifying footstrike pattern among runners, but discrepancies in VILR, stride length and cadence were found between slope conditions.

Shared Neuromuscular Performance Traits in Military Personnel with Prior Concussion.

To compare military personnel with at least one concussion during the past 1 month to 2 yr (CONCUSSED) to military branch-matched, age-matched, and Special Operations Forces group-matched controls (CONTROL) on physiological, musculoskeletal, and biomechanical performance. A total of 48 (24 CONCUSSED, 24 CONTROL) male Air Force and Naval Special Warfare Operators age 19 to 34 yr participated in the study. Participants self-reported demographics/injury history and completed the following assessments: 1) physiological-body composition, anaerobic power and capacity, aerobic capacity and lactate threshold; 2) musculoskeletal-lower extremity isokinetic strength testing, including time to peak torque; and 3) biomechanical-single-leg jump and landing task, including landing kinematics of the hip, knee and ankle. A machine learning decision tree algorithm (C5.0) and one-way ANOVA were used to compare the two groups on these outcomes. Despite nonsignificant differences using ANOVA, the C5.0 algorithm revealed CONCUSSED demonstrated quicker time to peak knee flexion angle during the single-leg landing task (≤0.170 s; CONCUSSED: n = 22 vs CONTROL: n = 14), longer time to peak torque in knee extension isokinetic strength testing (>500 ms; CONCUSSED: n = 18 vs CONTROL: n = 4) and larger knee flexion angle at initial contact (>7.7°; CONCUSSED: n = 18 vs CONTROL: n = 2). The findings supported the hypothesis that CONCUSSED military personnel would demonstrate altered neuromuscular control in landing strategies and muscular activation. Future research should assess prospectively neuromuscular changes after a concussion and determine if these changes increase risk of subsequent musculoskeletal injuries.

BIOMECHANICAL ANALYSIS OF SINGLE-LEG SQUAT WITH ISOKINETIC AND CONSTANT RESISTIVE FORCE USING CONTROLLABLE EXERCISE EQUIPMENT

BackgroundWe have reported that a resistive single-leg squat (RSLS) exercise using exercise equipment that generates various resistance forces was effective for increasing the load on the gluteus medius and preventing...

Joint Torques and Joint Reaction Forces During Squatting With a Forward or Backward Inclined Smith Machine

We developed a biomechanical model to determine the joint torques and loadings during squatting with a backward/forward-inclined Smith machine. The Smith squat allows a large variety of body positioning (trunk tilt, foot placement, combinations of joint angles) and easy control of weight distribution between forefoot and heel. These distinctive aspects of the exercise can be managed concurrently with the equipment inclination selected to unload specific joint structures while activating specific muscle groups. A backward (forward) equipment inclination decreases (increases) knee torque, and compressive tibiofemoral and patellofemoral forces, while enhances (depresses) hip and lumbosacral torques. For small knee flexion angles, the strain-force on the posterior cruciate ligament increases (decreases) with a backward (forward) equipment inclination, whereas for large knee flexion angles, this behavior is reversed. In the 0 to 60 degree range of knee flexion angles, loads on both cruciate ligaments may be simultaneously suppressed by a 30 degree backward equipment inclination and selecting, for each value of the knee angle, specific pairs of ankle and hip angles. The anterior cruciate ligament is safely maintained unloaded by squatting with backward equipment inclination and uniform/forward foot weight distribution. The conditions for the development of anterior cruciate ligament strain forces are clearly explained.

CSM 2010 Sports Physical Therapy Section Platform Presentations (Abstracts SPL1-SPL27)

CSM 2010 Sports Physical Therapy Section Platform Presentations (Abstracts SPL1-SPL27)

Impairment and disability following limb salvage procedures for bone sarcoma

Bone sarcomas are the fourth most common cancer in individuals under 25 years. Limb salvage procedures are popular for the treatment of osteosarcomas as they have functional and physiological benefits over traditional amputative procedures. The objective of this study was to apply disease specific measures to a group of intra-articular knee osteosarcoma patients and to evaluate structural and treatment variables predictive of the functional outcome scores. Twenty patients (10 ♀, 10 ♂) treated with tumour resection and endoprosthetic knee arthroplasty took part in the study. The Musculoskeletal Tumour Society (MSTS) rating scale and the Toronto Extremity Salvage Score (TESS) were used to assess impairment and disability respectively. Impairment was recorded as 83% and disability was recorded as 86% suggesting moderate to high function following limb salvage surgery. Task difficulty was shown to increase for activities requiring large knee flexion angles, presumably due to increased patellofemoral forces. Bivariate correlations revealed that loss of quadriceps musculature, knee extension strength and knee flexion range of motion were parameters moderately associated with the assessment instruments. ANOVA revealed no significant differences in impairment (P=0.962) or disability (P=0.411) between the differing types of prostheses. In conclusion clinicians and therapists should emphasise restoration of post-surgical range of motion and strength in order to enhance functional recovery.

Does landing technique displayed during volleyball training replicate the demands of competition?

Despite chronic lower extremity syndromes being extremely problematic in volleyball internationally, there is a lack of research pertaining to the demands experienced by volleyball players in terms of landings performed during competition and whether these are replicated during training. Therefore, the purpose of this study was to examine the differences in landing mechanics displayed by volleyball players during competition compared to training. Video data (25 Hz) of the Australian Men's volleyball team were collected for three training sessions and two competition matches at the Asian men's Volleyball Championships in 2003. Frequency data for six players were analysed (Chi-square analysis) to determine whether situation (training versus competition) was significantly (p < 0.05) related to a qualitative assessment of knee angle, landing style or movement task. The results revealed that, although players performed a greater number of landings during training (65%) compared to competition (35%) over similar duration, there was no significant relationship between situation and landing style. However, there were significant differences between training and competition when landings were classified according to movement task, landing style and knee angle. Interestingly, players landed with larger knee flexion angles than expected during both training (73% acute, 26% > square, 1% obtuse) and competition (59% acute, 38% square, 2% obtuse), possibly increasing knee joint loading and contributing to overuse syndromes. It was concluded that the effects of variations in landing knee angle on knee loading and the imbalance in landing demands between competition and training require further investigation as the basis of volleyball injury prevention initiatives.

Comparison of Open versus Closed Kinetic Chain Test Positions for Measuring Joint Position Sense

The purpose of this study was to determine if a difference exists in the reproducibility of knee joint flexion angles in an open versus a closed kinetic chain. Thirty generally healthy subjects (12 males, 18 females; mean age 23.8 years) participated. Subjects actively reproduced small, medium, and large knee flexion angles (with target angles of 15°, 45°, and 75°, respectively) in an open and a closed kinetic chain while being videotaped. Goniometric measurements were taken from the videotape of initial and reproduced joint angles. Data were analyzed using ANOVA with repeated measures on kinetic chain test position and joint angle. Subjects more accurately reproduced knee flexion angles in a closed kinetic chain position. The main effect for angle and the interaction of angle and test position were nonsignificant. The results indicate that knee joint position is more accurately reproduced in closed kinetic chain. Closed kinetic chain testing is also a more functional assessment of joint position sense, and thus closed kinetic chain assessment of lower extremity joint position sense is recommended.

Surgery simulation analysis of anterior advancement of the tibial tuberosity

The objective of this study is to evaluate the surgical outcome of anterior displacement of the tibial tuberosity (Maquet procedure) for reducing patellofemoral joint contact force. The in-vivo experimental knee joint geometric data with a biomechanical model was used to do the simulation of the Maquet procedure. Six healthy young adults performed weight-bearing knee flexion-extension by ascending a one-step stair. Dynamic X-ray images of the knee were continuously recorded by a video-fluoroscopic system. These X-ray images were analysed on a computerized digitizing system to get the knee joint geometric data. Based on the continuous in-vivo geometric data, computer surgery simulation was studied on six right knees with advancement of 3, 5,10,15, and 20 degrees of the patellar tendon insertion. Evaluation of the simulation consequences from a biomechanical view point showed that the Maquet procedure reduced the patellofemoral joint reaction force only up to 20% at 90 degrees of knee flexion angle. The patellofemoral joint reaction force had 50% reduction only when the knee flexion angle less than 20 degrees, and only when the patellar tendon was moved out by 15 or 20 degrees. This represented nearly 1 in. of the anterior displacement of the tibial tuberosity. The results also showed that the Maquet procedure would decrease up to 20% of the force transmission efficiency of the patellofemoral mechanism, which would cause the mechanical consequences of the operation to be only minor at larger knee flexion angles more than 20 degrees. These findings suggest that the Maquet procedure is only favourable to less active or older patients having small knee flexion angle activities.