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Osteosynthesis stability determination: In-vitro driving of a Thornton nail
882
Abstracts
TRABECULAR BONE STRUCTURE AND OUTER GEOMETRY OF THE PROXIMAL HUMAN FEMUR. Paul-Henri Cersckel and Sabri El Banna, Department of Orthopaedic Surgery, C.H.U. Andre V&ale, 706 Route de Gozee, B-6110 Montigny-le-Tilleul, Belgium. The aim was to relate the structure of trabecular bone and the proximal femur outer geometry. Six necropsy specimens were cut in the coronal plane. Sections were divided into zones based on the specimens contour. The structure of spongy bone was classified into four types (Gibson L.J., J. Biomech. 18: 317-328 (1985)), according two experimental morphometric criterias. Trabecular bone was considered to have (1) a closed type of structure if its relative density was over .23 and (2) an open type if its density was below .15. (3) Columnar spongy bone was found to be a structure whose elements had an angle between their main axis and a reference direction with a normal distribution (standard deviation ( 30 "); (4) asymmetric trabecular bone had a constant distribution for this angle. The medial trabecular system showed a closed columnar structure. The arcuate trabecular system and a layer of dense spongy bone next to the cortex had a closed type of structure: these trabeculae had a columnar Ward's triangle structure only in specimens with high relative density. and the core of the greater trochanter had an open asymmetric structure. All the data were reported The lateral trabecular system was not observed. on maps further used for modelling.
OSTEOSYNTHESIS STABILITY DETERMINATION: IN-VITRO DRIVING OF A THORNTON NAIL Sabri El Banna and Paul-Henri Cerckel, Departement of Orthopaedic Surgery, C.H.U. Andre Vesale, 706 route de Gozee, B-6110 Montigny-le-Tilleul, Belgium. The aim of the present experiment was to study the driving of a Thornton nail in the proximal epiphysis of a human femur to measure the strength of its trabecular bone and to predict the stability of the osteosynthesis. Seven femora were harvested (60 to 93 year old). Trabecular bone density was measured with computerized axial tomography. Driving of the nail was performed according a standardized technic and the The maxlmal length of its displacement was measured after each strike. All specimens showed a pull-out force was determined for each nail. two phase curve for the driving length versus the number of strikes. An indirect relation (r = -.92, p < .Ol) was found between trabecular bone density (951 to 1265 kg/m^3) and the driving length per strike (.01186 to 23.25 mm/strike). Correlation of the driving length per strike and the maximal pull-out force (608 to 1854 N) was also negative, but weak (-.72, p >. 05). Thus a sensitive relation between the driving length per strike and the strength of trabecular bone was established as far as the present study showed driving and density were linked, and others (McBROOM et Al., J Bone Joint Surg 67A: 1206-1214 (1985)) confirmed that density and strength were directly related. The relatron of the driving with the stability of the fixation was less evident.
COMPARISON OF BlOMECHANlCAl_ PARAMETERS DEMONSTRATED BY BRIAN BOITANO IN TRIPLE AND DOUBLE AXEL JUMPS Sergei Yu. Aleshinsky*, Sarah L. Smith**, Leonard 8. Jansen*, Francis Ramirez* *U, S. Figure Skating Association, 20 First Street, Colorado Springs, CO 80906, USA ** U.S. Olympic Committee, 1750 East Boulder Street, Colorado Springs, CO 80909, USA The Triple Axel (TA) is one of the most demanding and impressive figure skating jumps today. Although hundreds of skaters are capable of doing a Double Axel (DA), no more than three or four athletes in the World can consistently execute the TA. There is a great interest among skaters and coaches about technical demands of the TA, the first jump with more than three revolutions ever executed on the ice. Brian Boitano, the 1988 USA, World, and Olympic Champion, is very likely the best performer of this jump. His jumping and spinning technique was analyzed in conjunction with the U.S. Figure Skating Association/U.S. Olympic Committee Elite Skaters Project. The results, obtained from high speed filming (the data was processed by the computer program “ABC3D”), suggest that the TA technique requires more (than in the DA) “stopping” take-off, a bigger vertical velocity at the instant of take-off, a significantly bigger angular momentum in the flight phase, much greater strength to overcome larger centrifugal forces and more vertical position of the body’s longitudinal axis in flight.
Abstracts
TRABECULAR BONE STRUCTURE AND OUTER GEOMETRY OF THE PROXIMAL HUMAN FEMUR. Paul-Henri Cersckel and Sabri El Banna, Department of Orthopaedic Surgery, C.H.U. Andre V&ale, 706 Route de Gozee, B-6110 Montigny-le-Tilleul, Belgium. The aim was to relate the structure of trabecular bone and the proximal femur outer geometry. Six necropsy specimens were cut in the coronal plane. Sections were divided into zones based on the specimens contour. The structure of spongy bone was classified into four types (Gibson L.J., J. Biomech. 18: 317-328 (1985)), according two experimental morphometric criterias. Trabecular bone was considered to have (1) a closed type of structure if its relative density was over .23 and (2) an open type if its density was below .15. (3) Columnar spongy bone was found to be a structure whose elements had an angle between their main axis and a reference direction with a normal distribution (standard deviation ( 30 "); (4) asymmetric trabecular bone had a constant distribution for this angle. The medial trabecular system showed a closed columnar structure. The arcuate trabecular system and a layer of dense spongy bone next to the cortex had a closed type of structure: these trabeculae had a columnar Ward's triangle structure only in specimens with high relative density. and the core of the greater trochanter had an open asymmetric structure. All the data were reported The lateral trabecular system was not observed. on maps further used for modelling.
OSTEOSYNTHESIS STABILITY DETERMINATION: IN-VITRO DRIVING OF A THORNTON NAIL Sabri El Banna and Paul-Henri Cerckel, Departement of Orthopaedic Surgery, C.H.U. Andre Vesale, 706 route de Gozee, B-6110 Montigny-le-Tilleul, Belgium. The aim of the present experiment was to study the driving of a Thornton nail in the proximal epiphysis of a human femur to measure the strength of its trabecular bone and to predict the stability of the osteosynthesis. Seven femora were harvested (60 to 93 year old). Trabecular bone density was measured with computerized axial tomography. Driving of the nail was performed according a standardized technic and the The maxlmal length of its displacement was measured after each strike. All specimens showed a pull-out force was determined for each nail. two phase curve for the driving length versus the number of strikes. An indirect relation (r = -.92, p < .Ol) was found between trabecular bone density (951 to 1265 kg/m^3) and the driving length per strike (.01186 to 23.25 mm/strike). Correlation of the driving length per strike and the maximal pull-out force (608 to 1854 N) was also negative, but weak (-.72, p >. 05). Thus a sensitive relation between the driving length per strike and the strength of trabecular bone was established as far as the present study showed driving and density were linked, and others (McBROOM et Al., J Bone Joint Surg 67A: 1206-1214 (1985)) confirmed that density and strength were directly related. The relatron of the driving with the stability of the fixation was less evident.
COMPARISON OF BlOMECHANlCAl_ PARAMETERS DEMONSTRATED BY BRIAN BOITANO IN TRIPLE AND DOUBLE AXEL JUMPS Sergei Yu. Aleshinsky*, Sarah L. Smith**, Leonard 8. Jansen*, Francis Ramirez* *U, S. Figure Skating Association, 20 First Street, Colorado Springs, CO 80906, USA ** U.S. Olympic Committee, 1750 East Boulder Street, Colorado Springs, CO 80909, USA The Triple Axel (TA) is one of the most demanding and impressive figure skating jumps today. Although hundreds of skaters are capable of doing a Double Axel (DA), no more than three or four athletes in the World can consistently execute the TA. There is a great interest among skaters and coaches about technical demands of the TA, the first jump with more than three revolutions ever executed on the ice. Brian Boitano, the 1988 USA, World, and Olympic Champion, is very likely the best performer of this jump. His jumping and spinning technique was analyzed in conjunction with the U.S. Figure Skating Association/U.S. Olympic Committee Elite Skaters Project. The results, obtained from high speed filming (the data was processed by the computer program “ABC3D”), suggest that the TA technique requires more (than in the DA) “stopping” take-off, a bigger vertical velocity at the instant of take-off, a significantly bigger angular momentum in the flight phase, much greater strength to overcome larger centrifugal forces and more vertical position of the body’s longitudinal axis in flight.