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Erica M. Willadsen, Andrea B. Zahn and Chris J. Durall

another reporting an undesirable decrease in knee joint flexion angle at landing. 4 Clinical Bottom Line The risk of noncontact ACL injury is thought to be elevated during landing, cutting, or jumping with increased knee valgus and/or increased knee extension angulation. 1 , 3 Based on this review

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Mark A. Sutherlin, L. Colby Mangum, Shawn Russell, Susan Saliba, Jay Hertel and Joe M. Hart

reported in LBP individuals during running. 14 This increased knee joint stiffness is hypothesized to lead to inefficient force attenuation and could increase risk to the lumbar spine; however, force attention at the spine was not measured in the previous study. 14 The inclusion of lumbar spine stiffness

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Erik B. Simonsen, Morten B. Svendsen, Andreas Nørreslet, Henrik K. Baldvinsson, Thomas Heilskov-Hansen, Peter K. Larsen, Tine Alkjær and Marius Henriksen

The aim of the study was to investigate the distribution of net joint moments in the lower extremities during walking on high-heeled shoes compared with barefooted walking at identical speed. Fourteen female subjects walked at 4 km/h across three force platforms while they were filmed by five digital video cameras operating at 50 frames/second. Both barefooted walking and walking on high-heeled shoes (heel height: 9 cm) were recorded. Net joint moments were calculated by 3D inverse dynamics. EMG was recorded from eight leg muscles. The knee extensor moment peak in the first half of the stance phase was doubled when walking on high heels. The knee joint angle showed that high-heeled walking caused the subjects to flex the knee joint significantly more in the first half of the stance phase. In the frontal plane a significant increase was observed in the knee joint abductor moment and the hip joint abductor moment. Several EMG parameters increased significantly when walking on high-heels. The results indicate a large increase in bone-on-bone forces in the knee joint directly caused by the increased knee joint extensor moment during high-heeled walking, which may explain the observed higher incidence of osteoarthritis in the knee joint in women as compared with men.

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Walter Herzog and Lynda Read

The purpose of this study was to estimate cruciate ligament forces in Alpine skiing during a movement that has been associated with anterior cruciate ligament (ACL) tears. Resultant knee joint forces and moments were obtained from two skiers during a World Cup Downhill race using an inverse dynamics approach and a 2-D bilaterally symmetric system model. It was found that ACL forces were typically small for both skiers throughout the movement analyzed because quadriceps forces prevented anterior displacement of the tibia relative to the femur at the knee joint angles observed. However, for about 10 ms, loading conditions in the knee joint of Subject 2 (who displayed poor form) were such that large ACL forces may have been present. These particular loading conditions were never observed in Subject 1, who displayed good form. Since neither of the skiers was injured, it is not possible to draw firm conclusions about isolated ACL tears in Alpine skiing from the data at hand.

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Steven K. Boyd and Janet L. Ronsky

Abnormal joinl coniact mechanics in the knee joint due to loss of anterior cruciate ligament (ACL) are often speculated to play an important role in the development of osteoarthritis. In this study, a technique was developed so that contact of the patellofemoral (PF) joint could be estimated in situ using a mathematical contact model. The model inputs were PF joint kinematics measured in situ and the PF joint surface topology. Due to the small size of the joint, techniques for measuring joinl kinematics and surface topology with sufficient precision were paramount so that reasonable estimates of joint contact could be obtained. The sensitivity of the model to measurement errors was examined. Differences in joint contact between ACL-intacl and ACL-deficient conditions were analyzed. Statistically significant differences in contact areas were detected between the intact and ACL-deficient knee joint, and different coniact areas and locations as a function of joint angle and quadriceps muscular stimulation.

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Kristian M. O’Connor, Sarika K. Monteiro and Ian A. Hoelker

The purpose of this study was to compare the knee joint dynamics for males and females performing constrained cutting tasks to an unanticipated running and cutting maneuver. Sixteen male and 17 female recreational athletes were recruited to perform four cutting tasks; unanticipated run and cut (CUT), stride land and cut (SLC), far box-land and cut (FLC), and close box-land and cut (CLC). Three-dimensional knee joint kinematics and kinetics were recorded. Data were compared across gender and task with a 2 × 4 ANOVA (p < .05), and a factor analysis was performed to examine task relationships. There were significant group mean differences between the tasks and across genders. The factor analysis revealed high correlations between the three constrained tasks, but for variables typically associated with ACL injury risk there was a poor relationship to the CUT task. This was particularly true for the frontal plane variables. The constrained tasks were only moderately useful in predicting cutting mechanics.

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Thomas W. Kaminski and Thomas L. Schildwachter

Epiphyseal injuries present a special challenge to the sports medicine professional Salter-Harris Type III fractures involving the physis, epiphysis, and articular surface are uncommon (1). Because of the proximity of this fracture site to the knee joint, it is especially important that the clinician be aware of this type of injury when working with the adolescent athlete. This case adds to others previously reported in the English literature.

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Michael P. Reiman, Lori A. Bolgla and Daniel Lorenz

The purpose of this commentary is to describe the multifactorial relationships between hip-joint strength, range of motion, kinetics/kinematics, and various knee pathologies, specifically as they relate across an individual’s life span. Understanding the interdependence between the hip and knee joints in respect to functional activity is a necessary and relevant aspect for clinicians to investigate to ameliorate various pathological presentations at the knee that might have a proximal relationship.

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Michael A. Samaan, Eric K. Greska, Matthew C. Hoch, Joshua T. Weinhandl, Sebastian Y. Bawab and Stacie I. Ringleb

Context:

ACL injury may cause a lack of knee joint proprioception and motor control due to knee joint instability. ACL reconstruction restores knee joint stability, yet dynamic postural control may still be affected while performing dynamic tasks.

Objective:

To examine the effects of ACL injury and reconstruction on dynamic postural control using the Star Excursion Balance Test (SEBT) and single leg hop (SLH).

Participant:

One Division I female athlete.

Main Outcome Measure:

The athlete’s dynamic postural control, both pre- and postreconstruction, was compared with preinjury data using the method of minimal detectable change using reach distances obtained from the SEBT and hop distances from the SLH.

Results:

ACL injury and reconstruction affected the anterior, posteromedial, and posterolateral reach distances of the SEBT. Despite restoration of joint stability, anterior reach distance in the SEBT did not return to preinjury levels 27 months after ACL reconstruction. SLH distances decreased following injury but returned to preinjury levels 27 months after ACL reconstruction.

Conclusion:

Dynamic postural control and performance during the SEBT and SLH were affected by ACL injury and for extended periods of time after ACL reconstruction. Quadriceps inhibition and muscle strength of the involved limb may affect dynamic postural control both after ACL injury and reconstruction while performing the SEBT. Compensatory mechanisms at the hip and ankle may aid in performance of the SLH after reconstruction. Using baseline measurements, where possible, may help researchers better understand the effects of ACL injury and reconstruction on dynamic postural control.

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Brandon Warner, Kyung-Min Kim, Joseph M. Hart and Susan Saliba

Context:

Quadriceps function improves after application of focal joint cooling or transcutaneous electrical nerve stimulation to the knee in patients with arthrogenic muscle inhibition (AMI), yet it is not known whether superficial heat is able to produce a similar effect.

Objective:

To determine quadriceps function after superficial heat to the knee joint in individuals with AMI.

Design:

Single blinded randomized crossover.

Setting:

Laboratory.

Patients:

12 subjects (4 female, 8 males; 25.6 ± 7.7 y, 177.2 ± 12.7 cm, 78.4 ± 18.2 kg) with a history of knee-joint pathology and AMI, determined with a quadriceps central activation ratio (CAR) of <90%.

Intervention:

3 treatment conditions for 15 min on separate days: superficial heat using a cervical moist-heat pack (77°C), sham using a cervical moist pack (room temperature at about 24°C), and control (no treatment). All subjects received all treatment conditions in a randomized order.

Main Outcome Measures:

Central activation ratio and knee-extension torque during maximal voluntary isometric contraction with the knee flexed to 60° were collected at pre, immediately post, 30 min post, and 45 min posttreatment. Skin temperature of the quadriceps and knee and room temperature were also recorded at the same time points.

Results:

Three (treatment conditions) by 4 (time) repeated ANOVAs found that there were no significant interactions or main effects in either CAR or knee-extension torque (all P > .05). Skin-temperature 1-way ANOVAs revealed that the skin temperature in the knee during superficial heat was significantly higher than other treatment conditions at all time points (P < .05).

Conclusions:

Superficial heat to the knee joint using a cervical moist-heat pack did not influence quadriceps function in individuals with AMI in the quadriceps.