Measurement of migration of soft tissue by modified Roentgen stereophotogrammetric analysis (RSA): validation of a new technique to monitor rotator cuff tears.

The purpose of this study was to develop a technique to use Roentgen stereophotogrammetric analysis (RSA) to measure migration of soft-tissue structures after rotator cuff repair. RSA stereo films were obtained; images were analysed using a semi-automatic software program allowing 3D viewing of results. RSA imaging experiments were performed to validate the technique, using a glass phantom with implanted RSA beads and an animal model with steel sutures as RSA markers which were moved known distances. Repeated measurements allowed assessment of inter- and intra-observer variability at a maximum of 1.06 mm. RSA analysis of the phantom showed a variation up to 0.22 mm for static and 0.28 mm for dynamic studies. The ovine tissue specimen demonstrated that using steel sutures as RSA markers in soft tissue is feasible, although less accurate than when measuring bone motion. This novel application of RSA to measure soft tissue migration is practicable and can be extended to in vivo studies.

Kinematics of spinal motion during prolonged rowing.

Low back pain is a common problem in rowers of all levels. Few studies have looked at the relationship between rowing technique, the forces generated during the rowing stroke and the kinematics of spinal motion. Of particular concern with respect to spinal injury and damage are the effects of fatigue during long rowing sessions. A technique has been developed using an electromagnetic motion system and strain gauge instrumented load cell to measure spinal and pelvic motion and force generated at the handle during rowing on an exercise rowing ergometer. Using this technique 13 elite national and international oarsmen (mean age 22.43 +/- 1.5 y) from local top squad rowing teams were investigated. The test protocol consisted of a one hour rowing piece. During this session rowing stroke profiles were quantified in terms of lumbopelvic kinematics and stroke force profiles. These profiles were sampled at the start of the session and at quarterly intervals during the hour piece. From this data we were able to quantify the motion of the lumbar spine and pelvis during rowing and relate this to the stroke force profile. The stroke profiles over the one hour piece were then compared to examine the effects of prolonged rowing. This revealed marked increases in the amount of spinal motion during the hour piece. The relevance of this with regard to low back pain requires further investigation.

Movements of thoracic and abdominal compartments during ventilation at rest and during exercise.

The present investigation utilised simultaneous measurements of chest (Ch) and abdominal (Ab) circumferences and respiratory airflow to test the hypothesis that Ch circumferential expansion contributes proportionally little to tidal volume in the running Thoroughbred. During exercise, there were only small changes in Ch and Ab circumference and no increase with increasing tidal volume. At rest, walk and trot, the flow, Ch and Ab signals were in phase. However, during canter and gallop, the Ch and Ab changes were 180 degrees out of phase with each other and both were out of phase with airflow. In contrast to exercise, increase in ventilation at rest achieved by administration of lobeline resulted in a 4-6-fold increase in tidal volume; large excursions of the chest were always in phase with airflow. Furthermore, 3 horses showed an increase in chest circumference, demonstrating that chest stiffness per se does not preclude chest circumferential expansion. In conclusion, in the absence of significant increases in either Ch or Ab expansion during running, elongation of the thoracoabdominal segment may be the main determinant of tidal volume.