Background and Aim: Forces imposed on body members even on light working condition, may gradually result in damages caused by working. Persons engaged at goods sales centers including cashiers, may be to catch exhaustion and neuromuscular damage due to repetition of their wrist, elbow and shoulder joints movement. The aim of this research is to assess the relation between the work factors and personal characteristic in possibility of the above symptoms.
Materials and methods: The questioners form propounded at Stanford university question were asked and coded based on the target group, and having been reviewed and surveyed were later used in this research. This questioner included parts such as recording the personal characteristics, history of illnesses, clinical diagnosis and evaluation of the work environment and the hand tools. Selected individuals were randomly employed at goods sales centers from five geographical districts of Tehran.
Results: The most complaint of employees was pain and dysfunction in upper limbs, neck and shoulder. Half of subjects had carpal tunnel syndrome.
ength of work time and employment duration at sales centers increase probability of neck and shoulder pain.
Conclusion: The profession of cashiering at sales centers is one of the most stress causing jobs on the peripheral joints of upper limb, so that the lengths of working in this position and the amount of activity have a positive effect on the increase of neuromuscular disorder. Apply of correct pattern of using the tools and the equipment in this work environment could substantially control the negative effects of this type of job. The most of complains expressed by individuals taking part in this research have been related to sign and symptoms of involvement of median nerve in the wrist and referral pain in the neck, shoulder and arm.

Background and Aim: Since utilization of different patterns to perform voluntary movements influence human function, the aim of this study was to compare the selected kinematic parameters of active males in voluntary and involuntary gait initiation.

Materials and Methods: In this quazi-experimental study 13 young male subjects with age (23.3±3.1) years, height (1.75±.13) m, weight (68.9±7) kg and body mass index (22.4±1.8) k/m2, performed initiation of gait in 6 trials included three voluntary and three involuntary. Kinematic parameters measured by motion analysis system. K-S test was used to ensure the normal distribution of data and dependent T- test to compare within group variable at P0.05 level.

Result: The results showed that use of perturbation that leads to the initiation of motion, increased distance (p: 0.00) and velocity (p: 0.00) and reduced the time of gait initiation (p: 0.00), swing time (p: 0.00), stance time (p: 0.00) and double support time (p: 0.00), increased the amount of hip (p: 0.00) and knee flexion (p: 0.00) and decreased the amount of ankle dorsiflexion (p: 0.00). In addition, the displacement of the center of mass in the medio-lateral and vertical directions was decreased (p=0.03) and increased (p=0.01) respectively. Conclusion: The results indicate significant changes in most of the spatio-temporal parameters of gait initiation as a result of using Perturbation that leads to the initiation of motion. The results of this study can be recommended to be used in the field of gait initiation studies as well as in clinical cases to diagnose the normal and abnormality.

Background and Aim: Researches had shown that the high levels of shear and compression stresses that appear in the articular cartilage after meniscectomy are partly responsible for cartilage pathologies, such as osteoarthrosis . In this study, we probe to determine the stress distribution of the medial and lateral meniscus and to choose the appropriate region of meniscectomy.

Materials and Methods: Biomechanical 3D finite element model of the knee joint was generated from CT-scan images. Mimics modeled the bony structure of knee and Solidworks developed the medial and lateral meniscus.

Results: Under an axial femoral compressive load, the maximal contact stress in the articular cartilage after meniscectomy was about twice that of a healthy joint. The maximal contact pressures took place in the posterior region of the medial meniscus, with average values of 1.622 MPa and in the anterior horn of the lateral menisci with 1.159 MPa.

Results: Critical regions determine the allowed region of menisectomy for surgeon. Not only stress distribution doesn`t change by increasing of body weight or meniscectomy, but also the rate of stress increase after meniscectomy.