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Rebecca Avrin Zifchock, Kristamarie Pratt, Allison Brown and Howard Hillstrom

The purpose of this study was to compare the magnitude of knee kinematic coupling between genders and among open- and closed-chain tasks. A secondary purpose was to compare the consistency of knee kinematic coupling between genders and among open- and closed-chain tasks. Vector-coding methods were used to quantify coupling in the sagittal and transverse planes of the knee between full extension and 20 degrees of flexion as 10 males and 10 females walked, ascended and descended stairs, and performed a passive pendulum leg drop. An ANOVA showed no main effect of gender. There was a main effect of task, where coupling during the stance phase of walking was significantly greater than each of the other tasks. Intraclass correlation values suggested that males were slightly more consistent than females. A general lack of divergence between genders may be related to the tasks analyzed in this study. It is possible that more strenuous tasks may elicit larger differences.

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Lennart Scheys, Alberto Leardini, Pius D. Wong, Laurent Van Camp, Barbara Callewaert, Johan Bellemans and Kaat Desloovere

The availability of detailed knee kinematic data during various activities can facilitate clinical studies of this joint. To describe in detail normal knee joint rotations in all three anatomical planes, 25 healthy subjects (aged 22–49 years) performed eleven motor tasks, including walking, step ascent and descent, each with and without sidestep or crossover turns, chair rise, mild and deep squats, and forward lunge. Kinematic data were obtained with a conventional lower-body gait analysis protocol over three trials per task. To assess the repeatability with standard indices, a representative subset of 10 subjects underwent three repetitions of the entire motion capture session. Extracted parameters with good repeatability included maximum and minimum axial rotation during turning, local extremes of the flexion curves during gait tasks, and stride times. These specific repeatable parameters can be used for task selection or power analysis when planning future clinical studies.

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Takayuki Hasegawa, Toshiro Otani, Kentaro Takeda, Hideo Matsumoto, Kengo Harato, Yoshiaki Toyama and Takeo Nagura

The purpose of the current study was to longitudinally evaluate how preoperative knee kinematics change after ACL reconstruction. Three-dimensional gait analysis using the point cluster method was undertaken on the same subjects preoperatively and at 3, 6, and 12 months after ACL reconstructive surgery. Thirteen subjects (7 males, 6 females) were examined while performing 2 different activities at self-selected speeds: walking and walk-pivoting (walking, pivoting toward the landed limb side and walking away). The contralateral knees of subjects at 12 months postoperatively were selected as control knees. Flexion range in the stance phase increased with time after surgery, but remained lower than in the contralateral knee, even at 12 months postoperatively (P < .05) during walking and walk-pivoting. The rotation pattern during walking and walk-pivoting showed an offset toward external rotation by 6 months postoperatively compared with control knees, while at 12 months postoperatively the offset had nearly disappeared and the movement pattern resembled that in control knees. These findings suggest that a return to sport participation by 6 months after ACL reconstruction requires careful consideration. Depending on the type of sport, activity restriction even after 12 months may need to be considered to allow complete kinematic restoration.

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John H. Hollman, Jeffrey M. Hohl, Jordan L. Kraft, Jeffrey D. Strauss and Katie J. Traver

Context:

Abnormal lower extremity kinematics during dynamic activities may be influenced by impaired gluteus maximus function.

Objective:

To examine whether hip-extensor strength and gluteus maximus recruitment are associated with dynamic frontal-plane knee motion during a jump-landing task.

Design:

Exploratory study.

Setting:

Biomechanics laboratory.

Participants:

40 healthy female volunteers.

Main Outcome Measures:

Isometric hip-extension strength was measured bilaterally with a handheld dynamometer. Three-dimensional hip and knee kinematics and gluteus maximus electromyography data were collected bilaterally during a jumplanding test. Data were analyzed with hierarchical linear regression and partial correlation coefficients (α = .05).

Results:

Hip motion in the transverse plane was highly correlated with knee motion in the frontal plane (partial r = .724). After controlling for hip motion, reduced magnitudes of isometric hip-extensor strength (partial r = .470) and peak gluteus maximus recruitment (partial r = .277) were correlated with increased magnitudes of knee valgus during the jump-landing task.

Conclusion:

Hip-extensor strength and gluteus maximus recruitment, which represents a measure of the muscle’s neuromuscular control, are both associated with frontal-plane knee motions during a dynamic weight-bearing task.

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Pui W. Kong and Norma G. Candelaria

This study aimed to 1) determine the suitability of using spanning set (SS) to measure knee angle variability in the entire gait cycle and 2) assess the sensitivity of SS magnitude to the order of polynomial fitted to the standard deviation (SD) curves of the mean ensemble curves. Eight runners performed 10 over-ground barefoot running trials, followed by 8 min of accommodation, and then another 10 trials. Knee angle variabilities before and after accommodation were assessed using the SS and two conventional methods: mean coefficient of variation and mean SD. The sensitivity of the SS magnitude was assessed by calculating SS using (n–2), (n–1), (n+1), and (n+2)th orders of polynomials, where nth is the best fit order. Variability decreased after accommodation using the conventional methods (p < .05) but not the SS. The SS magnitude was sensitive to the order of polynomial. It is concluded that the SS may not be appropriate for measuring knee kinematic variability in the entire gait cycle during over-ground barefoot running.

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Gianluca Gatti

This article presents the validation of a technique to assess the appropriateness of a 2 degree-of-freedom model for the human knee, and, in which case, the dominant axes of flexion/extension and internal/external longitudinal rotation are estimated. The technique relies on the use of an instrumented spatial linkage for the accurate detection of passive knee kinematics, and it is based on the assumption that points on the longitudinal rotation axis describe nearly circular and planar trajectories, whereas the flexion/extension axis is perpendicular to those trajectories through their centers of rotation. By manually enforcing a tibia rotation while bending the knee in flexion, a standard optimization algorithm is used to estimate the approximate axis of longitudinal rotation, and the axis of flexion is estimated consequently. The proposed technique is validated through simulated data and experimentally applied on a 2 degree-of-freedom mechanical joint. A procedure is proposed to verify the fixed axes assumption for the knee model. The suggested methodology could be possibly valuable in understanding knee kinematics, and in particular for the design and implant of customized hinged external fixators, which have shown to be effective in knee dislocation treatment and rehabilitation.

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Inga Krauss, Thomas Ukelo, Christoph Ziegler, Detlef Axmann, Stefan Grau, Thomas Horstmann and Alex Stacoff

Results from instrumented gait analysis vary between test situations. Subject characteristics and the biomechanical model can influence the total amount of variability. The purpose of this study was to quantify reliability of gait data in general, and with respect to the applied model, and investigated population group. Reliability was compared between a functional and a predictive gait model in subjects with knee osteoarthritis and healthy controls. Day-to-day consistency for sagittal plane variables was comparable between models and population groups. Transversal plane variables relative to joint excursion showed larger inconsistency for repeated measures, even for a more sophisticated biomechanical approach. In conclusion, the presented reliability data of sagittal plane kinematics should be used for a reasonable interpretation of results derived in clinical gait analysis. Variables of the transversal plane should not be used as long as sources of error are not sufficiently minimized.

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Özlem Aslan, Elif Balevi Batur and Jale Meray

Context: Osteoarthritis (OA) is the most common chronic joint condition. Muscle dysfunction plays a critical role in the pathogenesis of knee OA. Objective: It has been suggested that the agonist–antagonist strength relationship for the knee may be better described by a functional hamstring/quadriceps (H/Q) ratio (Hconcentric/Qeccentric: the representative of knee flexion and Qeccentric/Hconcentric: the representative of knee extension). Therefore, in this study, the authors aimed to investigate this ratio and its importance for knee OA. Design: Cross-sectional study. Setting: Research clinic. Patients or Other Participant(s): Twenty healthy women and 20 women with grade 2 or grade 3 primer knee OA between the age of 50 and 80 years were included in this study. Intervention(s): Concentric and eccentric peak torque of quadriceps and hamstring muscles were evaluated for all individuals in patient and control groups with a Cybex isokinetic device. Functional H/Q ratio is calculated manually. Main Outcome Measure(s): Functional H/Q torque ratios were analyzed between the patients with OA and healthy individuals by using the isokinetic system. Results: The values of peak torque of hamstring concentric and eccentric and quadriceps concentric for the patient group were significantly lower than the control group (P < .05). No statistically important difference was found for quadriceps eccentric peak torque between 2 groups (P > .05). H/Q ratio for extension in the patient group was significantly higher than the control group (P < .05), whereas the H/Q ratio for flexion in the patient group was significantly lower than the control group (P < .05). Conclusion: This study showed the weakness of both quadriceps and hamstring muscles in patients with knee OA. The combination of functional H/Q ratio with hamstring and quadriceps muscles concentric and eccentric strength values can help to analyze the knee functions and develop preventive-therapeutic approaches for knee OA.

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Christopher D. Harner, Tracy M. Vogrin and Savio L-Y. Woo

This article discusses the anatomy and biomechanics of the posterior cruciate ligament (PCL) and PCL reconstructions and their implications for clinical management of PCL injuries. The PCL consists of two functional components, the anterolateral and posteromedial, based on their reciprocal tensioning patterns. The anterolateral has been the focus of single-bundle PCL reconstructions. Recent biomechanical studies have indicated that the posteromedial bundle also plays an important role, and double-bundle PCL reconstructions have also been proposed. The PCL works closely with the posterolateral structures in providing posterior knee stability. The effects of several surgical variables, including graft fixation, associated injuries, and tunnel placement, that can significantly affect the outcome of PCL reconstruction are discussed. With improved knowledge of the PCL, new reconstructive techniques are being developed, offering the potential of more closely replicating the anatomy and biomechanics of the normal PCL and improving clinical outcomes of PCL injuries.

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Jacob T. Hartzell, Kyle B. Kosik, Matthew C. Hoch and Phillip A. Gribble

ntervention (or Assessment): jump landing OR single leg jump landing OR single limb jump landing OR stop jump OR jump landings • C omparison: None • O utcome(s): knee kinematics OR lower extremity kinematics OR landing kinematics OR knee motion OR motion analysis OR kinematics OR neuromuscular control The