PubMed Health⌕ Search

Biomedical subjects

F Bojsen-Møller

Publications and source records attributed to F Bojsen-Møller.

24 records · Page 2Linked to original sources
PubMed1989

Shock absorbency of factors in the shoe/heel interaction--with special focus on role of the heel pad.

The heel pad acts as a shock absorber in walking and in heel-strike running. In some patients, a reduction of its shock-absorbing capacity has been connected to the development of overuse injuries. In this article, the shock absorption of the heel pad as well as external shock absorbers are studied. Individual variation and the effect of trauma and confinement on the heel pad were specifically investigated. Drop tests, imitating heel impacts, were performed on a force plate. The test specimens were cadaver heel pads (n = 10); the shoe sole component consisted of ethyl vinyl acetate (EVA) foam and Sorbothane inserts. The shock absorption was significantly greater in the heel pad than in the external shock absorbers. The mean heel pad shock absorption was 1.1 times for EVA foam and 2.1 times for Sorbothane. The shock absorption varied by as much as 100% between heel pads. Trauma caused a decrease in the heel pad shock absorbency (24%), whereas heel pad confinement increased the shock absorbency (49% in traumatized heel pads and 29.5% in nontraumatized heel pads). These findings provide a biomechanical rationale for the clinical observations of a correlation between heel pad shock absorbency loss and heel strike-dependent overuse injuries. To increase shock absorbency, confinement of the heel pad should be attempted in vivo.

Adult↗
PubMed1979

Significance of free-dorsiflexion of the toes in walking.

Dissection reveals that the ball of the foot contains a connective tissue framework with transverse, vertical, and sagittal fibers, all connecting the skin with the proximal phalanges of the toes. Dorsiflexion of the toes tightens the framework and thereby restricts passive movements of the skin, enabling shear forces to be transferred to the skeleton. An electromechanical oscillator was constructed that applied oscillatory shear forces of constant amplitude (+/- 0.2 N) to the skin and at the same time measured the resulting motions. It was found that the toes should be dorsiflexed by 35--40 degrees to restrict skin mobility to 50 per cent and by 50 degrees to restrict it maximally. The results were compared to actual dorsiflexions of toes during walking. These dorsiflexions were measured on slow motion film and with still pictures with light tracks formed by light emitting diodes. Maximal dorsiflexion during push off was found to be 60 degrees for feet walking without shoes, 45--50 degrees for feet walking in soft shoes, and 25--30 degrees for feet walking in a stiff shoe of the minus-heel type. Dorsiflexion was further found significant for arch support and for the mechanics of the forefoot during push-off.

Biomechanical Phenomena↗
PubMed1979

Calcaneocuboid joint and stability of the longitudinal arch of the foot at high and low gear push off.

The calcaneocuboid joint was studied in ligamentous specimens of ten human feet, and in skeletons of two gorillas (Gorilla gorilla beringei), six chimpanzees (Pan troglodytes), three orangutans (Pongo pygmaeus) and 25 human feet. The movement of the transverse tarsal joint was further studied in a living foot on a walk-way with a glass plate inserted, and with an underlying mirror. In man the joint is shaped as an asymmetrical sector of one end of an hour-glass shaped surface of revolution with its main axis oriented longitudinally in the foot. The calcaneocuboid joint becomes close packed by a pronation of the forefoot in relation to the hind foot because of a congruency between the joint surfaces obtained in this position and because the calcaneus overhangs the cuboid dorsally and stops the movement. At low gear push off the foot is inverted and the calcaneocuboid joint loose packed. The stresses are absorbed across the fibular, postaxial border of the foot. At high high gear push off there is a functional pronation of the forefoot with a stabilization of the transverse tarsal joint and a more effective tightening of the plantar aponeurosis. The foot becomes a rigid lever for propulsion. In contrast to the human condition, the anthropoid calcaneus has an anteromedial extension associated with symmetry of the calcaneocuboid joint. The calcaneus does not overhang the cuboid and there appears to be no close packed position. Correspondingly, the anthropoid foot has a mid-tarsal break at each push off in addition to the metatarsophalangeal break.

Animals↗