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Gabriel Andrade Paz, Jason DeFreitas, Marianna de Freitas Maia, Jurandir Silva, Vicente Lima and Humberto Miranda

Study Design:

Crossover design.

Context:

Excessive valgus and varus force which affected the knee joint during dynamic tasks has been often associated to lower extremity injuries. Strategies to increase the resistance against these asymmetries (eg, the use of a physioball between the knees or elastic bands around the knees) are often applied in rehabilitation and conditioning programs.

Objective:

The purpose of this study was to investigate the effect of performing leg press (LP) 45° using a physioball and elastic band over multiple sets with submaximal loads on electromyographic (EMG) amplitude and fatigue indices.

Methods:

18 trained females volunteered (age: 24.4 ± 2.1 y; height: 168.1 ± 4 cm; body mass: 65.1 ± 4.4 kg) participated in this study. The 10 repetition maximum (RM) loads were determined for the LP. Then, 3 experimental protocols were followed in a randomized crossover design over 3 nonconsecutive days: control protocol—the participants performed 4 LP sets; physioball between knees—4 LP sets were performed with the physioball between the knees; elastic band—4 LP sets were performed with the elastic band involving the knees. Ten repetitions were performed during each set with 70% of 10-RM loads; EMG spectral indices (CRMS and Cf5) was collected from the biceps femoris (BF), vastus lateralis (VL), vastus medialis obliquus (VMO), and rectus femoris (RF) muscles.

Results:

Higher levels of CRMS and Cf5 were noted for RF, VL, and VM muscles using the physioball and elastic band when compared with control protocol, respectively. CRMS index of BF muscle was significantly higher using physioball and elastic band protocol versus control condition, respectively.

Conclusion:

Therefore, both physioball and elastic band can be adopted during LP with the goal to reduce excessive varus and valgus forces, respectively, even performing consecutive sets with submaximal loads. Furthermore, this may be an interesting alternative to increasing quadriceps activation and improving the knee joint stabilization.

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Brian D. Street and William Gage

associated with gait asymmetry after joint replacement have been argued to create degenerative changes in the contralateral limb. 19 The results of the current study suggest that gait asymmetry associated with knee joint loading, in particular, the vertical impact force at heel strike and the peak knee

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Scott W. Cheatham and Kyle R. Stull

in understanding the effects of RM for clinical practice. 21 , 22 , 28 The main purpose of this investigation was to measure the effects of a prescribed RM program on knee joint passive ROM and pain perception among healthy experienced and nonexperienced individuals. A secondary purpose was to

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Kathy J. Simpson, Jae P. Yom, Yang-Chieh Fu, Scott W. Arnett, Sean O’Rourke and Cathleen N. Brown

The objective of the study was to determine if prophylactic ankle bracing worn by females during landings produces abnormal lower extremity mechanics. Angular kinematic and ground reaction force (GRF) data were obtained for 16 athletically experienced females who performed brace and no-brace drop landings. The brace condition displayed reduced in/external rotation and flexion displacements about the ankle and knee joints and increased vertical and mediolateral GRF peak magnitudes and rate of vertical GRF application (paired t test, P < .05). The ankle and knee joints landed in a less plantar flexed and more flexed position, respectively. No significant ab/adduction outcomes may have occurred due to interparticipant variability and/or a lack of brace restriction. Conclusion: During typical landings, this lace-up brace increases vertical GRF, decreases ankle and knee joint displacements of flexion and int/external rotation, but minimally affects ab/adduction displacements.

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Charlie A. Hicks-Little, Richard D. Peindl, Tricia J. Hubbard-Turner and Mitchell L. Cordova

Context:

Knee osteoarthritis (OA) is a debilitating disease that affects an estimated 27 million Americans. Changes in lowerextremity alignment and joint laxity have been found to redistribute the medial and/or lateral loads at the joint. However, the effect that changes in anteroposterior knee-joint laxity have on lower-extremity alignment and function in individuals with knee OA remains unclear.

Objective:

To examine anteroposterior knee-joint laxity, lower-extremity alignment, and subjective pain, stiffness, and function scores in individuals with early-stage knee OA and matched controls and to determine if a relationship exists among these measures.

Design:

Case control.

Setting:

Sports-medicine research laboratory.

Participants:

18 participants with knee OA and 18 healthy matched controls.

Intervention:

Participants completed the Western Ontario McMaster (WOMAC) osteoarthritis questionnaire and were tested for total anteroposterior knee-joint laxity (A-P) and knee-joint alignment (ALIGN).

Main Outcome Measures:

WOMAC scores, A-P (mm), and ALIGN (°).

Results:

A significant multivariate main effect for group (Wilks’ Λ = 0.30, F 7,26 = 8.58, P < .0001) was found. Knee-OA participants differed in WOMAC scores (P < .0001) but did not differ from healthy controls on ALIGN (P = .49) or total A-P (P = .66). No significant relationships were identified among main outcome measures.

Conclusion:

These data demonstrate that participants with early-stage knee OA had worse pain, stiffness, and functional outcome scores than the matched controls; however, ALIGN and A-P were no different. There was no association identified among participants’ subjective scores, ALIGN, or A-P measures in this study.

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Gulcan Harput, A. Ruhi Soylu, Hayri Ertan, Nevin Ergun and Carl G. Mattacola

Context:

Coactivation ratio of quadriceps to hamstring muscles (Q:H) and medial to lateral knee muscles (M:L) contributes to the dynamic stability of the knee joint during movement patterns recommended during rehabilitation and important for daily function.

Objective:

To compare the quadriceps-to-hamstring and medial-to-lateral knee muscles' coactivation ratios between men and women during the following closed kinetic chain exercises performed on a balance board: forward lunge, side lunge, single-leg stance, and single-leg squat.

Design:

Cross-sectional.

Participants:

20 healthy subjects (10 female and 10 male).

Main Outcome Measures:

Surface electromyography was used to measure the activation level of quadriceps (vastus lateralis and medialis) and hamstrings (biceps femoris and medial hamstrings) during forward- and side-lunge, single-leg-stance, and single-leg-squat exercises. Subjects were instructed during each exercise to move into the test position and to hold that position for 15 s. EMG was recorded during the 15-s isometric period where subjects tried to maintain a “set” position while the foot was on a balance board. Analysis of variance was used for statistical analysis.

Results:

There was a significant exercise-by-gender interaction for Q:H ratio (F3,48 = 6.63, P = .001), but the exercise-by-gender interaction for M:L ratio was not significant (F3,48 = 1.67, P = .18). Women showed larger Q:H ratio in side-lunge exercises than men (P = .002). Both genders showed larger M:L and lower Q:H ratio in a single-leg-stance exercise than in the other exercises.

Conclusions:

The results indicate that the forward- and side-lunge and single-leg-squat exercises should not be recommended as exercise where a balanced coactivation between quadriceps and hamstring muscles is warranted. Single-leg-stance exercise could be used when seeking an exercise where the ratio is balanced for both women and men.

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Sinem Suner-Keklik, Gamze Cobanoglu-Seven, Nihan Kafa, Mustafa Ugurlu and Nevin Atalay Guzel

Context: Proprioception is the basic element of the spontaneous control of movement, balance and joint stability. Therefore, it is necessary for the execution of walking and daily and sport activities. Loss of proprioception of the knee, which may cause a new injury, is important to evaluate the position sense of the joint during the rehabilitation period. However, the evaluation methods that are used are very expensive, complicated and nonportable, or the measuring method is difficult to implement. Objective: We demonstrated the validity and reliability of knee proprioception measurements performed in the open kinetic chain position and closed kinetic chain position with a dual inclinometer. Design: We assessed the validity and intratester reliability of a digital inclinometer for measuring the knee joint position sense in different positions. Setting: Clinical laboratory. Participants: We enrolled 22 participants (age = 21.8 ± 0.95 y, height = 172 ± 9.1 cm, weight = 64.9 ± 14 kg) into the study. Intervention: The same investigator used an inclinometer to take knee proprioception measurements in open and closed kinetic chain positions. Main Outcome Measures: The relative angular error was calculated by taking the arithmetic average of the difference between the target angle and reproduced angle and was the main outcome measure. Results: We found that the dynamometer-inclinometer had a moderate ICC value (ICC = 0.594, SEM = 1.60, P = .005), whereas inclinometer t1 vs inclinometer t2 (ICC = 0.778, SEM = 0.62, P < 0.001) and closed kinetic chain position t1 and closed kinetic chain position t2 (ICC = 0.888, SEM = 0.63, P < 0.001) had high ICC values. Conclusion: Knee proprioception measurements performed with a dual inclinometer were reliable in the closed kinetic chain position in healthy, sedentary individuals and were valid and reliable in the open kinetic chain position.

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Anna Lina Rahlf, Klaus-Michael Braumann and Astrid Zech

ensured. Patients in the intervention and sham groups were blinded regarding the treatment. Both groups were told to receive an effective kinesio tape for the knee joint, only with a difference in the application area. The control group was not blinded. All measurements were accomplished at the university

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Satoshi Hamai, Ken Okazaki, Satoru Ikebe, Koji Murakami, Hidehiko Higaki, Hiroyuki Nakahara, Takeshi Shimoto, Hideki Mizu-uchi, Yukio Akasaki and Yukihide Iwamoto

The purpose of this study was to investigate in vivo kinematics in healthy and osteoarthritic (OA) knees during stepping using image-matching techniques. Six healthy volunteers and 14 patients with a medial OA knee before undergoing total knee arthroplasty performed stepping under periodic anteroposterior radiograph images. We analyzed the three-dimensional kinematic parameters of knee joints using radiograph images and CT-derived digitally reconstructed radiographs. The average extension/flexion angle ranged 6°/53° and 16°/44° in healthy and OA knees, with significant difference in extension (P = .02). The average varus angle was –2° and 6° in healthy and OA knees, with a significant difference (P = .03). OA knees showed 1.7° of significantly larger varus thrust (P = .04) and 4.2 mm of significantly smaller posterior femoral rollback (P = .04) compared with healthy knees. Coronal limb alignment in OA knees significantly correlated with varus thrust (R 2 = .36, P = .02) and medial shift of the femur (R 2 = .34, P = .03). Both normal and OA knees showed no transverse plane instability, including anteroposterior, mediolateral directions, or axial rotation. In conclusion, OA knees demonstrated different kinematics during stepping from normal knees: less knee extension, larger varus thrust, less posterior translation, and larger medial shift.

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Thomas W. Kernozek, Naghmeh Gheidi, Matthew Zellmer, Jordan Hove, Becky L. Heinert and Michael R. Torry

joint was modeled as a ball-in-socket joint with 3-DOF based on Bell et al. 33 The knee joint was modeled as a 1-DOF hinge joint. The subtalar joint was modeled with 1-DOF, and the ankle joint was modeled with 2-DOF. Three hundred muscle tendon units were represented, where muscle parameters, muscle