Graft perforations favor osteoinduction. Studies of rabbit cortical grafts sterilized with ethylene oxide.

The healing of freeze-dried, ethylene oxide sterilized, segmental, allogenic cortical bone grafts was investigated in 15 rabbits using a 2-cm ulnar diaphyseal defect. Five different groups of bone grafts were evaluated: 1) unperforated undemineralized, 2) perforated undemineralized, 3) unperforated demineralized, 4) perforated demineralized, and 5) perforated demineralized grafts enclosed by silicone rubber (Silastic) sheets. There were 3 animals in each group.

The effect of simulated fracture-angulations of the tibia on cartilage pressures in the knee joint.

The effects of angular deformities of the tibia on the contact areas and pressures on cartilage in the knee were measured with use of pressure-sensitive film. Six cadaver knees were mounted in a test-frame, such that the offset and tilt of the knee relative to the load-axis simulated that due to angular deformities of the tibia of 5, 10, 15, or 20 degrees of varus or valgus at the levels of the proximal, middle, and distal thirds. Angulation had little effect on the contact area.

Biomechanical model of the human shoulder joint--II. The shoulder rhythm.

A method to investigate the rhythm of the human shoulder, i.e. the interplay between the motion of constituent parts of the shoulder, has been devised and tested.

Subacromial pressure during diagnostic shoulder tests.

The pressure in the subacromial bursa during passive provocation tests and during active motion was recorded in five healthy persons, and in seven patients with a subacromial pain syndrome. During the passive impingement test, the mean bursa pressure increased from 6 to 56 mmHg in healthy persons and from 8 to 45 mmHg in the patients. A passive test for anterior glenohumeral instability yielded bursa pressures below 0 mmHg in both groups.

Pressure recording in the subacromial bursa.

The microcapillary infusion (MCI) technique was evaluated in monitoring pressure in the subacromial bursa in 30 shoulders in healthy volunteers. The total pressure in the bursa was studied as the volunteers held their arms at rest and as they lifted their arms and held them lifted with or without a weight of 1 kg in the hands. The pressure in the bursae at rest averaged 8 mm Hg and was found stable during a 40-min period.

Biomechanical model of the human shoulder--I. Elements.

In a first step of a biomechanical modelling of the human shoulder the points of application of muscle forces to the bones were determined in a dissection study on four human shoulder specimens. A kinematic description of the shoulder was presented employing bone fixed coordinate systems. Actions of the shoulder muscles were modelled as a system of forces acting along ideal strings.

Shoulder pain and heavy manual labor.

The problem of the increasingly common shoulder pain syndromes in industry was investigated by biomechanic and epidemiologic methods. Rotator cuff tendinitis constitutes a major problem in people with arduous occupations, i.e.

Electromyographic analysis of shoulder muscle load.

The influence of hand tool weight and arm position on shoulder muscle load was studied by electromyography. The investigation was made to facilitate recommendations on work place design. The aim is to reduce the occurrence of occupational shoulder disorders in industry.