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Laura C. Slane, Stijn Bogaerts, Darryl G. Thelen and Lennart Scheys

fundamental understanding of the joint, and is also important in clinical diagnosis, where passive motion is still the most common technique for diagnostic evaluation. Better characterization of passive knee motion may also influence the design of geometric models of the knee, 24 – 26 which often model

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Kenny Guex, Francois Fourchet, Heiko Loepelt and Gregoire P. Millet

Context:

A passive knee-extension test has been shown to be a reliable method of assessing hamstring tightness, but this method does not take into account the potential effect of gravity on the tested leg.

Objective:

To compare an original passive knee-extension test with 2 adapted methods including gravity’s effect on the lower leg.

Design:

Repeated measures.

Setting:

Laboratory.

Participants:

20 young track and field athletes (16.6 ± 1.6 y, 177.6 ± 9.2 cm, 75.9 ± 24.8 kg).

Intervention:

Each subject was tested in a randomized order with 3 different methods: In the original one (M1), passive knee angle was measured with a standard force of 68.7 N (7 kg) applied proximal to the lateral malleolus. The second (M2) and third (M3) methods took into account the relative lower-leg weight (measured respectively by handheld dynamometer and anthropometrical table) to individualize the force applied to assess passive knee angle.

Main Outcome Measures:

Passive knee angles measured with video-analysis software.

Results:

No difference in mean individualized applied force was found between M2 and M3, so the authors assessed passive knee angle only with M2. The mean knee angle was different between M1 and M2 (68.8 ± 12.4 vs 73.1 ± 10.6, P < .001). Knee angles in M1 and M2 were correlated (r = .93, P < .001).

Conclusions:

Differences in knee angle were found between the original passive knee-extension test and a method with gravity correction. M2 is an improved version of the original method (M1) since it minimizes the effect of gravity. Therefore, we recommend using it rather than M1.

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Thomas P. Dompier, Craig R. Denegar, W.E. Buckley, S. John Miller, Jay Hertel and Wayne J. Sebastianelli

Context:

Flexibility is promoted as essential to physical fitness, but the mechanisms limiting it are not fully understood.

Objective:

To investigate the effects of general anesthesia on hamstring extensibility.

Design:

Repeated measures.

Setting:

Hospital operating room.

Subjects:

Eight volunteers undergoing orthopedic surgeries unrelated to the tested limb.

Measurement:

Three measurements of passive knee extension (PKE) taken before and after administration of general anesthesia. The force applied during the measurements was consistent between trials.

Results:

Mean PKE range of motion (ROM) was significantly greater before anesthesia (75.0° ± 11.8°) than after (53.3° ± 17°; t = 5.6, P < .001). Pearson product correlation revealed a significant correlation between the mean difference in PKE ROM between treatment conditions and subjects’ body weight (r = .91, P < .05).

Conclusions:

The findings might be attributable to diminished neural drive to the antagonist muscle groups and suggest a more complex neural control of flexibility than simply neural drive to an agonist muscle.

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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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Gregory S. Ford, Margaret A. Mazzone and Keith Taylor

Design:

Pretest–posttest.

Objective:

To determine the effect of 4 durations of static hamstring stretching on knee-extension passive range of motion (KE-PROM).

Context:

Effects of longer (90 and 120 seconds) static hamstring stretching on PROM have not been established relative to more typically recommended 30- or 60-second durations.

Subjects:

35 healthy college-age subjects with >20° loss of KE-PROM.

Outcome Measure:

KE-PROM.

Intervention:

5-week program of single daily stretch for 30, 60, 90, or 120 seconds.

Results:

Static stretching was effective in increasing KE-PROM regardless of stretch duration (P < .0001). A significant improvement was identified in mean PROM for each stretching group, but no difference existed among the 4 stretch-duration groups. The control group’s mean PROM decreased (mean = -3.2°, SD = 1.9), whereas each stretching group increased PROM (means 1.9° to 3.6°).

Conclusions:

Five weeks of daily static hamstring stretching for 30, 60, 90, or 120 seconds increase KE-PROM. Similar benefits were achieved regardless of stretch duration, suggesting that clinicians need not perform static hamstring stretches of more than 30 seconds.

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Joanna Diong and Robert D. Herbert

Contracture after stroke could be due to abnormal mechanical interactions between muscles. This study examined if ankle plantarflexor muscle contracture after stroke is due to abnormal force transmission between the gastrocnemius and soleus muscles. Muscle fascicle lengths were measured from ultrasound images of soleus muscles in five subjects with stroke and ankle contracture and six able-bodied subjects. Changes in soleus fascicle length or pennation during passive knee extension at fixed ankle angle were assumed to indicate intermuscular force transmission. Changes in soleus fascicle length or pennation were adjusted for changes in ankle motion. Subjects with stroke had significant ankle contracture. After adjustment for ankle motion, 9 of 11 subjects demonstrated small changes in soleus fascicle length with knee extension, suggestive of intermuscular force transmission. However, the small changes in fascicle length may have been artifacts caused by movement of the ultrasound transducers. There were no systematic differences in change in fascicle length (median between-group difference adjusting for ankle motion = -0.01, 95% CI -0.26–0.08 mm/degree of knee extension) or pennation (-0.05, 95% CI -0.15–0.07 degree/degree of knee extension). This suggests ankle contractures after stroke were not due to abnormal (systematically increased or decreased) intermuscular force transmission between the gastrocnemius and soleus.

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Carlan K. Yates, Michael R. McCarthy, Howard S. Hirsch and Mark S. Pascale

This study examined the benefits and possible risks of immediate continuous passive motion after autogenous patellar tendon reconstruction of the anterior cruciate ligament. Thirty patients scheduled to undergo ACL reconstruction were prospectively randomized into two groups, CPM and non-CPM. Postoperatively, those in the non-CPM group wore a hinged knee brace. Those in the CPM group were kept on a CPM machine 16 hrs a day while in the hospital and they used it 6 hrs a day for the first 2 weeks postoperatively. After surgery the patients were assessed for hemovac drainage, range of motion, swelling, effusion, subjective pain, and use of pain medication. The CPM group had significantly less swelling and effusion, required less pain medication, and had greater knee flexion. No differences were found in hemovac drainage, passive knee extension, or subjective pain reports despite a significantly greater use of pain medication in the non-CPM group. The results suggest that immediate CPM after ACL reconstruction is safe and facilitates early range of motion by decreasing the amount of pain medication, effusion, and soft tissue swelling.

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José M. Muyor, Pedro A. López-Miñarro and Fernando Alacid

The aim was to determine the relationship between hamstring muscle extensibility and sagittal spinal curvatures and pelvic tilt in cyclists while adopting several postures. A total of 75 male cyclists were recruited for this study (34.79 ± 9.46 years). Thoracic and lumbar spine and pelvic tilt were randomly measured using a Spinal Mouse. Hamstring muscle extensibility was determined in both legs by a passive knee extension test. Low relationships were found between hamstring muscle extensibility and spinal parameters (thoracic and lumbar curvature, and pelvic tilt) in standing, slumped sitting, and on the bicycle (r = .19; P > .05). Significant but low relationships were found in maximal trunk flexion with knees flexed (r = .29; P < .05). In addition, in the sit-and-reach test, low and statistically significant relationships were found between hamstring muscle extensibility for thoracic spine (r = –.23; P = .01) and (r = .37; P = .001) for pelvic tilt. In conclusion, hamstring muscle extensibility has a significant relationship in maximal trunk flexion postures with knees flexed and extended, but there are no relationships while standing or on the bicycle postures.

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. Henry * Scott M. Lephart * Jorge Giraldo * David Stone * Freddie H. Fu * 11 2001 10 4 246 256 10.1123/jsr.10.4.246 The Effect of General Anesthesia on Passive-Knee-Extension Range of Motion Thomas P. Dompier * Craig R. Denegar * W.E. Buckley * S. John Miller * Jay Hertel * Wayne J

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Original Research Reports The Effect of 4 Different Durations of Static Hamstring Stretching on Passive Knee-Extension Range of Motion Gregory S. Ford * Margaret A. Mazzone * Keith Taylor * 5 2005 14 2 95 107 10.1123/jsr.14.2.95 Research What Are the Validity of the Single-Leg-Squat Test and