In vivo loading data for the rotator cuff would be of value to scientists and clinicians interested in the shoulder in the testing of surgical repairs, design of rehabilitation programs and for finite element models.

A technique for insertion and retrieval of the Arthroscopically Insertable Force Probe (AIFP - Microstrain Inc. Burlington, Vermont, USA) from the subscapularis is described was initially established in a cadaveric model. Ethical approval was obtained for AIFP insertion into the subscapularis tendon of volunteers during diagnostic shoulder arthroscopy. An in situ calibration was carried out using a modified arthroscopic grasper ( Smith and Nephew, Huntingdon, UK). After motor effects of interscalene block had worn off dynamic data relating to subscapularis tendon loading was collected. The AIFPs were removed through a port site by traction on an O (3.5 metric) nylon suture without complication.

Maximum loading of the subscapularis tendon was measured during internal rotation from neutral with the arm fully adducted. Forces measured exceeded 200N.

This paper describes a novel technique for the insertion, calibration and retrieval of AIFPs from the rotator cuff. In vivo tendon loading data was obtained. The techniques described may be applied to other structures of interest to orthopaedic surgeons.

Objective: This study challenges the assumption that pivot shift is abolished once anterior stability is restored in the ACL reconstructed knee. Method: The kinematics of 7 cadaver knees were studied with the Flock-of-Birds, as pivot shift was repeated in intact, ACL deficient, then ACL reconstructed specimens with grafts tensioned at 0, 10, 20, 40 and 60N. All were BPTB grafts in similar positions. Results: Pivot shift is described as a sudden reduction from internal rotation of 8.57 +/− 2.3° at knee flexion of 24.2 +/− 11°; achieved with iliotibial loading of 56.2 +/− 11.5N, 2.26 +/− 0.6Nm valgus load and 1.5 +/− 0.4Nm internal torque. Internal rotation was significantly reduced at 40N (3.2°, p< 0.005) and 60N (2.9°, p=0.001). At maximum tension, all specimens felt stable and pivoted less. This reduction of internal rotation averaged 62%; ranging from 42% (subtle pivot) to 100% (complete abolition). At 90° knee flexion external rotation was reduced with graft tension of 60N, but not significantly (p=0.03). The range of knee flexion during reduction of the pivot shift was not significantly altered. Conclusions: Tensions of grafts that restored anterior stability (40N & 60N) did not always abolish the pivot shift, but significantly reduced it. This may account for complaints of subtle instability despite surgical reconstruction. Grants: DTT Lie was supported by a grant from the Singapore National Medical Research Council.

Low back pain (LBP) 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 oar during rowing on an exercise rowing ergometer. Using this technique 13 elite national and international oarsmen (mean age 22.43 ± 0.02 years) from local top squad rowing teams were investigated. The test protocol comprised 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 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 fatigue. This revealed marked changes and increases in the amount of spinal motion during the hour piece suggesting that to maintain stroke force profiles athletes were utilising greater ranges of spinal motion. The relevance of this with regard to low back pain however, requires further investigation.