Publications by authors named "Jason D Wening"

4 Publications

  • Page 1 of 1

Does knee osteoarthritis alter the neuromuscular responses to a perturbation during single lower limb stance?

J Geriatr Phys Ther 2005 ;28(3):93-101

RUSH Oak Park Hospital, Department of Physical Therapy, Oak Park, IL 60304, USA.

Purpose: Evidence substantiating an association between knee osteoarthritis (OA) and altered joint protection responses is relevant to the management of knee OA. The purpose of this study was to detect neuromuscular response times of the vastus lateralis and biceps femoris muscles following a perturbation during single lower limb stance. We hypothesized that muscle response times are: (1) delayed in older adults with knee OA when compared to young and older adults (without diagnosed knee OA) and (2) dependent on the magnitude of load released.

Subjects: Ten young adults, 10 older adults, and 7 older adults with symptomatic knee OA participated.

Methods: While in single lower limb stance, the subjects flexed the knee into a range of 33 to 37 degrees while a posterior load of either 6 or 9 kg was applied at the proximal tibia. The load was released after the subjects held the required position for 1 full second. Muscle response times were measured by electromyography. Separate 3 (group) by 2 (load) mixed factorial analysis of variance procedures were performed for electromyography data from the vastus lateralis and biceps femoris.

Results: There was no difference in vastus lateralis response times between older adults with knee OA and older adults or between older adults with knee OA and young adults. Older adults did have longer vastus lateralis response times than young adults. There was no difference in biceps femoris response times between older adults with knee OA and older adults; however, both groups had longer biceps femoris response times than young adults. Furthermore, there were no differences in either vastus lateralis or biceps femoris response times between 6 kg and 9 kg loads.

Conclusion: Although knee OA did not alter muscle responses in our study, the type of functional weightbearing perturbation described could be safely used in the physical therapy clinic to help improve balance and stability while decreasing discomfort in older adults with symptomatic knee OA.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1519/00139143-200512000-00005DOI Listing
January 2006

Mechanisms of limb collapse following a slip among young and older adults.

J Biomech 2006 24;39(12):2194-204. Epub 2005 Aug 24.

Department of Physical Therapy, University of Illinois at Chicago, Chicago, IL 60612, USA.

Recovery from a large perturbation, such as a slip, can be successful when stability of movement can be reestablished with protective stepping. Nevertheless, one dilemma for executing a protective step is that its liftoff can weaken support against limb collapse. This study investigated whether failures in limb support leading to falls after a protective step result from insufficient joint moment generation, and whether such insufficiency is greater among older fallers. A novel, unexpected slip was induced immediately following seat-off during a sit-to-stand. Joint work and mechanical energy were calculated for 43 young (9 falls, 34 recoveries) and 22 older (13 falls, 9 recoveries) adults who responded with a protective step. Comparisons of the work produced at three joints of the bilateral lower limbs revealed that insufficient concentric knee and hip extensor work prior to step liftoff was a primary differentiating factor between falling and recovery, regardless of age. Also, during stepping, fallers regardless of age failed to limit the eccentric knee extensor work at their stance limb sufficiently to retard rapid knee flexion and the consequent potential energy loss. We concluded that young and older fallers had comparable weak limb support. The greater fall incidence among the older adults likely resulted from a greater proportion of subjects who responded to the slip with insufficient knee extensor support, possibly attributable to age-differences in chair-rising. One strategy to address this dilemma may rely on task-specific training to enhance feedforward control that improves movement stability, and thus lessens the reliance on protective stepping.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jbiomech.2005.07.004DOI Listing
November 2006

Changes in the long head of the biceps tendon in rotator cuff tear shoulders.

Clin Biomech (Bristol, Avon) 2005 Feb;20(2):162-5

MedSport and Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, The University of Michigan, 400 N. Ingalls Building Ann Arbor, MI 48109-0486, USA.

Background: Morphologic changes in the long head of the biceps tendon have been described in association with rotator cuff disease, yet mechanical significance of these changes remains unclear.

Methods: An experiment was designed to test the hypotheses that the cross-sectional area and material properties of the long head of the biceps tendon are different in shoulders with full thickness rotator cuff tears and shoulders with intact rotator cuff tendons. Seven pairs of cadaver shoulders were tested. In each pair one shoulder had a full thickness rotator cuff tear and the other did not. Thus, a matched design was used. Cross sectional areas were measured. Tendon material properties were measured using an optical strain system.

Findings: We were unable to detect a statistically significant difference in the long head of the biceps area or material properties between tendons in shoulders with and without rotator cuff tears. An a priori power analysis was conducted indicating the sample size was sufficient to detect a difference of 70 MPa in the elastic modulus measurement.

Interpretation: Our data indicate there is no difference in the long head of the biceps cross sectional area or material properties. Therefore, the long head of the biceps tendon appears to retain its material properties in the presence of a rotator cuff tear. The clinical significance of this finding is that the long head of the biceps can be retained in the presence of a rotator cuff tear without concern that mechanical properties have substantially deteriorated.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clinbiomech.2004.09.009DOI Listing
February 2005

Quantitative morphology of full thickness rotator cuff tears.

Clin Anat 2002 Jan;15(1):18-22

University of Michigan, Orthopaedic Research Lab, Ann Arbor, Michigan 49109, USA.

The occurrence of full thickness rotator cuff tears (RCTs) at time of death, the size and distribution of those tears among the tendons of the rotator cuff, and the anterior to posterior and medial to lateral dimensions of the RCTs were determined. A subset of 57 shoulders from a group of 414 were found to have full thickness rotator cuff tears. The three-dimensional coordinates of specific bony landmarks and points defining the circumference of the RCT were digitized using a Flock of Birds DC electromagnetic tracking device. Bony landmarks were used to determine the separation between adjacent tendons of the rotator cuff. Points describing the circumference of the RCT were used to calculate the area of the tear. The majority of tears occurred in the supraspinatus tendon alone (25), or in both the supraspinatus and infraspinatus tendons (22). The areas of the RCTs ranged from 0.07 cm(2) to 19.17 cm(2) with an average of 4.43 cm(2). The mean anterior to posterior length was 1.95 cm. The mean medial to lateral length was 1.98 cm.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ca.1086DOI Listing
January 2002
-->