Ali Sheikhzadeh

Biomechanical differences between unilateral and bilateral landings from a jump: gender differences.

Objective:To determine the effect of landing type (unilateral vs. bilateral) and gender on the biomechanics of drop landings in recreational athletes. Design:This study used a repeated measures design to compare bilateral and unilateral landings in male and female athletes. A repeated measures multivariate analysis of variance (type of landing*gender) was performed on select variables. Setting:Biomechanics laboratory. Participants:Sixteen female and 16 male recreational athletes. Main Outcome Measures:Kinetic, kinematic, and electromyographic (EMG) data were collected on participants while performing bilateral and unilateral landings from a 40-cm platform. Results:Compared to bilateral landings, subjects performed unilateral landings with increased knee valgus, decreased knee flexion at initial contact, decreased peak knee flexion, decreased relative hip adduction, and increased normalized EMG of the rectus femoris, medial hamstrings, lateral hamstrings, and medial gastrocnemius (P < 0.005). During both types of landing, females landed with increased knee valgus and normalized vertical ground reaction force (VGRF) compared to males (P < 0.009), however, the interaction of landing type*gender was not significant (P = 0.29). Conclusions:Compared to bilateral landings, male and female recreational athletes performed unilateral landings with significant differences in knee kinematic and EMG variables. Female athletes landed with increased knee valgus and VGRF compared to males during both types of landing.

Effects of Spinal Flexion and Extension Exercises on Low-back Pain and Spinal Mobility in Chronic Mechanical Low-back Pain Patients

It has been estimated that one fourth to one half of all patients treated in physical therapy clinics suffer from low-back pain. The purpose of this study was to compare the effects of spinal flexion (Group I) and extension (Group II) exercises on low-back pain severity and thoracolumbar spinal mobility in chronic mechanical low-back pain patients. Both groups had significantly less low-back pain after treatment (P < .10). There was no significant difference, however, between the spinal flexion and extension exercises in reduction of low-back pain severity. The results indicated a significant difference between the groups in increasing the sagittal mobility (P < .10). The results did not indicate any significant difference between and within groups in increasing the coronal and transverse mobility of the thoracolumbar spine. Either the spinal flexion or extension exercises could be used to reduce chronic mechanical low-back pain severity, but the flexion exercises had an advantage in increasing the sagittal mobility within a short period of time.

Perioperating nurses and technicians’ perceptions of ergonomic risk factors in the surgical environment

The aim of this study was to identify the magnitude and characteristics of work-related musculoskeletal complaints among perioperative nurses and technicians (PNT) and determine the associated ergonomic risk factors in the operating room (OR) environment based on self-report and focus group discussion. The 50 PNTs who participated in the study completed a self-report survey for musculoskeletal symptoms, Job Description Questionnaire, and Psychometric Evaluation Questionnaire, and participated in focus groups to discuss potential OR ergonomic risk factors. The results of the study demonstrated a high prevalence of work-related musculoskeletal disorders (WMSD) among PNTs, with lower back pain the most prevalent (84%) complaint, followed by ankle/foot (74%) and shoulder (74%) pain. In addition, lower back pain (31%), followed by ankle/knee (24%) pain were found to be the main causes of absenteeism from work. Participants suggested simple ergonomic and engineering solutions can be adopted to improve the work environment of PNTs.

The relationship of torque, velocity, and power with constant resistive load during sagittal trunk movement.

Strength and fitness studies have been used to determine the predictability of back pain episodes. Tests have demonstrated that isometric strength displays little prognostic value in the development of low-back pain. Static isometric tests have achieved widespread usage due to the simplicity and safety of protocols, the readily available technology, and the low administrative costs. Dynamic lifting models have, however, predicted significantly higher spinal loads than those derived from static models. The objectives of this study were twofold: to investigate the relationship of the torque, velocity, and power to the resistive load during trunk flexion and extension, and to develop predictive models for these relationships for the subjects performance of the 10th, 50th, and 90th percentile distribution. The results of the study found that the flexion/extension torque had a positive linear correlation with the set resistance; the velocity displayed a negative linear correlation, while power had a quadratic relationship with the resistance.

Kinematic analysis of dynamic shoulder motion in patients with reverse total shoulder arthroplasty.

BACKGROUND Reverse total shoulder arthroplasty (rTSA) has been used to treat patients with irreparable rotator cuff dysfunction. Despite the proven clinical efficacy, there is minimal information regarding the underlying changes to the shoulder kinematics associated with this construct. Therefore, we sought to examine the kinematics of dynamic shoulder motion in patients with well-functioning rTSA. METHODS We tested 12 healthy subjects and 17 patients with rTSA. All rTSA patients were able to elevate their arms to at least 90° and received the implant as the primary arthroplasty at least 6 months before testing. On average, the rTSA patients elevated their arms to 112° ± 12° (mean ± SD) and reported an American Shoulder and Elbow Surgeons outcome score of 90.6 ± 6.3. A 3-dimensional electromagnetic motion capture device was used to detect the dynamic motion of the trunk, scapula, and humerus during bilateral active shoulder elevation along the sagittal, scapular, and coronal planes. RESULTS In both healthy and rTSA shoulders, the majority of the humeral-thoracic motion was provided by the glenohumeral motion. Therefore, the ratio of glenohumeral to scapulothoracic (ST) motion was always greater than 1.62 during elevation along the scapular plane. In comparison to healthy subjects, however, the contribution of ST motion to overall shoulder motion was significantly increased in the rTSA shoulders. This increased contribution was noted in all planes of shoulder elevation and was maintained when weights were attached to the arm. CONCLUSION Kinematics of the rTSA shoulders are significantly altered, and more ST motion is used to achieve shoulder elevation.

Three-dimensional motion of the scapula and shoulder during activities of daily living

The purpose of this study was to describe 3-dimensional scapular motion during the activities of daily living (ADL) and the full range of arm motion, and to suggest a standardized method for evaluating scapular mobility. Eight healthy subjects between the ages of 25-40, with no prior history of shoulder pathology or surgery for the past 12 months, were recruited for this study. Touching 8 predetermined landmarks on the head and the trunk was used to simulate ADL. Touching the contralateral ear and contralateral shoulder resulted in the maximum scapular protraction 46 degrees (8 degrees) and 48 degrees (8 degrees), respectively, and the maximum degrees of the scapular anterior tilt, -11 degrees (4 degrees) and -11 degrees (5 degrees), respectively. Asking patients to reach to the back of the neck, and the contralateral shoulder, the clinician can evaluate the overall scapular mobility in all directions. A protocol controlling the performance variability during ADL tasks was suggested to improve the clinical evaluation of the shoulder joint complex. Findings of this study can guide clinicians to identify specific tasks which may relate to particular shoulder girdle dysfunction.

Glycosphingolipid antibodies in serum in patients with sciatica

Study Design. Serum antibody titers against 10 different glycosphingolipids were investigated by enzyme-linked immunosorbent assay in three groups of patients: patients with acute sciatica (Group IA, radicular pain for 32 ± 36 days, n = 68), a subgroup of these patients 4 years later (Group IB, n = 23), and patients undergoing lumbar discectomy because of disc herniation (Group II, n = 37). Objectives. To investigate the immunologic response in sciatica patients by analyzing circulating autoantibodies against glycosphingolipids, molecules highly expressed in cells from the nervous system, and the possible correlation of such antibodies to clinical and imaging findings as well as to subjective symptoms. Summary of Background Data. The titers of glycosphingolipid antibodies are elevated in neurologic diseases with autoimmune stimulation such as Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy. Methods. Antiglycosphingolipid antibodies were assayed by a microtiter enzyme-linked immunosorbent assay method. Antibody titers were related to a healthy population by a method that judges all positive results (positive result = patient sera/pooled blood donor serum >2, at titer 1/400) as indicating a pathologic condition. Results. Increased levels of circulating antibodies against one or more glycosphingolipids were detected in 71% of patients with acute sciatica, in 61% of sciatica patients at a 4-year follow-up visit (eight antigens analyzed) and in 54% in patients undergoing discectomy. These frequencies were somewhat higher than, and in the last group similar to, those reported for generalized nervous system disorders with autoimmune involvement. In the acute sciatica patients, positive neurologic findings were associated with increased levels of two of the examined antibodies: 3′LM1 (immunoglobulin M and/or immunoglobulin G), P = 0.023, and GD1a (immunoglobulin M), P = 0.017. Conclusion. The presence of glycosphingolipid antibodies in patients with sciatica and disc herniation suggests an activation of the immune system and thus a process possibly involved in the pathophysiology of sciatica. The autoimmune response was not limited to antibodies against one specific glycosphingolipid target; rather, an overall increase in autoantibodies against nervous system–associated glycosphingolipids was observed. These results encourage further studies of the pathophysiologic and clinical relevance of autoimmune responses in patients with sciatica and disc herniation.

The effect of posture on triaxial strength in different directions: Its biomechanical consideration with respect to incidence of low-back problem in construction industry

Abstract There has been no previous study investigating the triaxial strength potentials of the trunk muscles in a pre-rotated spine. A great many lifting tasks in construction industry occur while the trunk has already been flexed in the sagittal plane. The purpose of this study was (a) to measure the triaxial maximum isometric strength of normal male subjects in all six possible directions while standing in three different postures: 0, 20, and 36 degrees of trunk flexion; (b) to assess the effect of posture on the maximum isometric torque in all six directions. The highest maximum isometric extension and flexion torques were recorded at 36 degrees of trunk flexion - they increased by 68% and 36% with respect to upright posture. The flexion angle significantly affected the measured torques in the intended plane of exertion during attempted flexion and extension, while the torques in the accessory planes were affected in the attempted right and left lateral bending and axial rotation (p

Recovery of impaired muscle function in severe sciatica

Abstract This is a prospective cohort study of patients with acute treated severe sciatica. The objectives of the study are, firstly, to describe the recovery of muscle performance by manual and isokinetic muscle testing in patients with acute severe sciatica over 1 year, and secondly, to discuss the potential clinical relevance of the isokinetic testing of the ankle for patients with acute sciatica. In clinical daily practice, muscle performance is evaluated by means of isometric manual tests. Different authors using manual muscle tests have reported the long-term outcome of the muscle function in patients with sciatica. Overall, the results are good in terms of the recovery of muscle strength. However, it is not clear whether the isometric strength is sufficiently relevant to evaluate the more complete muscle performance of the affected muscles in patients with sciatica. This study presents data on the muscle recovery measured with manual testing and isokinetic testing of patients with severe sciatica. Consecutive patients admitted to the Cantonal Hospital for conservative management of severe acute sciatica were eligible for inclusion in the study. Patients were evaluated at admission, discharge, and follow-up at 3, 6, and 12 months. All the visits included a standardized clinical examination and the completion of questionnaires. Imaging and electromyography were conducted at the first visit. Isokinetic muscle tests at 30°/s and 120°/s were performed at discharge and follow-up visits. Manual and isokinetic tests were performed on foot and ankle flexor and extensor muscles. Eighty-two consecutive patients (66% men), with a mean age of 43 (±10.3) years, entered the study. The prevalence of major muscle weakness was low, with 7% of patients unable to perform toe walking and 11% unable to walk on the heel at visit one. Moreover, motor deficit defined as a score of 4 or less (out of 5) was found in 15% of subjects at the first evaluation. Such severe deficits were not found during the last three visits. The isokinetic tests showed a higher prevalence of muscle function impairment. At visit 5, the isokinetic test showed impaired muscle function recovery from 23% to 32%, while the manual test showed almost full recovery. The issues of agreement between manual and isokinetic muscle testing are discussed. In this selected and homogeneous cohort of patients, the prevalence of motor deficit was rather low and the outcome excellent according to the results of the manual testing. Isokinetic muscle tests showed a higher prevalence of deficit and a much slower recovery. The manual muscle test is a crude clinical test. For more in-depth muscle performance evaluation, additional testing may be necessary, especially for those patients with physically demanding jobs or activities.

Quantification of Trunk Muscle Performance in Standing, Semistanding and Sitting Postures in Healthy Men

The purpose of this study was to determine trunk muscle performance in the sitting, semistanding, and standing postures during isometric and dynamic extension and flexion movements. Twenty-five male subject volunteers, with no previous history of back pain participated in the study. A triaxial dynamometer that measures torque, angular position, and velocity was used to measure isometric and dynamic motor output. The dynamometer allows testing in the sitting and standing postures. A custom-designed module also allowed testing in the semistanding posture. Each subject was tested in two sessions. The first session included the physical examination and three trials of isometric maximum voluntary contractions in the three postures. The second session included the dynamic performance against a resistance equal to 50% of the effort, as measured in the first session. Subjects were instructed to perform five repetitive flexion and extension cycles as fast end accurately as possible with maximum effort. An analysis of variance with repeated measures design was used to investigate the effects of the postures (Standing, semistanding and sitting), the direction of exertion (flexion and extension), and the interaction effects of the isometric and dynamic parameters (maximum and average torque, velocity, power, and range of motion). The effects of direction (F=98, P<0.001) and the interaction of posture and direction (F=7.9, P<0.001) were significant. The maximum isometric flexion strength was significantly higher in the standing posture than in semistanding and sitting. The maximum isometric extension was not affected by the posture (sitting, semistanding and standing). The average power in standing was twice that of sitting and semistanding (P<0.0001). During dynamic performances, only the main effects of posture and direction were significant. There was no difference between the semistanding, and sitting postures in terms of the dynamic performances. Maximum torque and velocity in standing were significantly higher than in semistanding, and sitting, which should be considered in the optimization of workplace design.