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The effect of hallux sesamoid resection on flexion moment arms of the MTP joint
606
Abstracts
THE DIABETICFOOT WITH PARTIALAMPUTATION - A BIOMECHANICALSTUDY Peter R. Cavanagb, Jan S. Ulbrecht, Ge Wu, Mary Becker, John C. Garbalosa, Ian Alexandd, and James Campbell*. Center for Locomotion Studies, Penn State University, University Park, PA 16803, #The Crystal Clinic, Akron, OH, and *The Cleveland Clinic Foundation, Cleveland, OH. This study examined the function of partially amputated feet during gait to ascertain what therapeutic intervention might be needed for successful management. First step bilateral plantar pressure distribution data were collected using a Novel EMED pressure platform in 14 patients with a mean age of 60.1 years (sd 15.6) duration of diabete8 21.5 years (sd 12.1), duration from first surgery 4.5 years (sd 4.6) with 15 transmetatarsal amputations without Achilles tendon tenotomies. Mean peak pressures from the five trials were calculated in four regions of the feet: the heel and the medial, central and lateral regions of the anterior margin of the foot. Mean peak forefoot pressures were significantly higher (pc.05) in the feet with partial amputation (705 kPa, sd 233) when compared to the contralateral foot (551 kPa, sd 202). Heel pressures tended to be lower on the amputated side (NS, ~7.05). The data suggests that enhanced postoperative care including therapeutic footwear is vital to the successful long term management of diabetic patients with partial foot amputation.
A FINITE ELEMENT ANALYSIS OF THE RADIOCARPALJOINT DonaldD. Andefion BiomcchsnicsResearchLaboratory, Allegheny-SingaResearchInstitute, 320E. NorthAve.,F%ttsburgh. PA 15212 Itisclearfromasweyofcunentlitcraturethattherelationshipbetweenmalreducedintra-articularfrac~dthcdis$lradiusandthe subsequent onsetofradiocarpalw (OA)is clinicallyimportam,yetpoorlym NonBnearcuuacttiniteeleme~~tanalysis of thejuxtarticular regionis a feasibbCompuQVional optionwell-suitedforinvestigation of localtissuestressesin themdioca@ join& It providesausefultoolfor~~~gthemechanicalimplicationsofimprecisenductiond~~~fracturcofthedistal~~ The broadobjectiveof thisresearchis thedevelqent of a we.&verified ccmput&nal modelof themdioca@ joint,which.in amc& with experimental modelspreviouslydeveloped.will he capahleof providing#dance towardrigawsly gnnmdcd&mvements ia distalradius in@articular~turemanagementtechaiques.Aplanestrain~tcelemcntmodcloftheradiocarpalpint~asbeendevelopedandvaifiad throughcompadsonwithpreviouslydevelopedexperimental andanalyticalmod& of thejoist. IIIgeneral,the s&ss distdbutionsobmined withchef~~elementrodelwereconsistentwithresultspreviouslyplblishedforotherarticularpints. ?hemodelinclu&sthedistalmdius and~oprimaryload-bearingcarlxllb((thelunateandthescaphoid).aswellasthcarti thesebones. Themodelholdspomise forprovidingnew insightintothenhukmshipsbetweenjuxtariicular loadtransmission anda&cd surfacegeometryin makcducediatra-a&alartitllre of thedisralradius
THE EFFECT OF HALLUX SESAMOID RESECTION ON
FLEXION MOMENT ARMS OF THE MTP JOINT Rhonda L. Aper, Charles L. Saltzman, and Thomas D. Brown Departments of Orthopaedic Surgery and Biomedical Engineering, The University of Iowa, Iowa City, IA 52242, USA. Intrinsic disorders of the great toe sesamoids (e.g., fracture, osteochondritis, avascular necrosis) can become a chronic source of considerable disability. There is no consensus, however, as to the optimal surgical treatment. The wide variation in the treatment of such disorders points to a fundamental lack of understanding of the functional biomechanical significance of the hallux sesamoids. In this study, the functional significance of the hallux sesamoid bones was quantified by measuring the effective tendon moment arm (ETMA) of the flexor hallucis brevis (FHB) force. The intact case was compared with three levels of progressive sesamoid resection: distal half of the medial sesamoid excised, entire medial sesamoid excised, and both the medial and lateral sesamoids excised. The experimental method consisted of applying a known active functional load to the FHB muscle of fresh Frozen cadaver specimens (the great toe being maintained at specific angles of dorsiflexion) while recording corresponding resisting force from three orthogonally mounted transducers. Results showed the ETMAs to decrease significantly (p < 0.05) only with dual excision. The functionally measured ETMA values of the FHB were less than expected, given the overall physical size of the MTP joint. The ETMA values suggest that the true center of rotation is located plantarwards of the geometric center, close to the tendon centroid.
Abstracts
THE DIABETICFOOT WITH PARTIALAMPUTATION - A BIOMECHANICALSTUDY Peter R. Cavanagb, Jan S. Ulbrecht, Ge Wu, Mary Becker, John C. Garbalosa, Ian Alexandd, and James Campbell*. Center for Locomotion Studies, Penn State University, University Park, PA 16803, #The Crystal Clinic, Akron, OH, and *The Cleveland Clinic Foundation, Cleveland, OH. This study examined the function of partially amputated feet during gait to ascertain what therapeutic intervention might be needed for successful management. First step bilateral plantar pressure distribution data were collected using a Novel EMED pressure platform in 14 patients with a mean age of 60.1 years (sd 15.6) duration of diabete8 21.5 years (sd 12.1), duration from first surgery 4.5 years (sd 4.6) with 15 transmetatarsal amputations without Achilles tendon tenotomies. Mean peak pressures from the five trials were calculated in four regions of the feet: the heel and the medial, central and lateral regions of the anterior margin of the foot. Mean peak forefoot pressures were significantly higher (pc.05) in the feet with partial amputation (705 kPa, sd 233) when compared to the contralateral foot (551 kPa, sd 202). Heel pressures tended to be lower on the amputated side (NS, ~7.05). The data suggests that enhanced postoperative care including therapeutic footwear is vital to the successful long term management of diabetic patients with partial foot amputation.
A FINITE ELEMENT ANALYSIS OF THE RADIOCARPALJOINT DonaldD. Andefion BiomcchsnicsResearchLaboratory, Allegheny-SingaResearchInstitute, 320E. NorthAve.,F%ttsburgh. PA 15212 Itisclearfromasweyofcunentlitcraturethattherelationshipbetweenmalreducedintra-articularfrac~dthcdis$lradiusandthe subsequent onsetofradiocarpalw (OA)is clinicallyimportam,yetpoorlym NonBnearcuuacttiniteeleme~~tanalysis of thejuxtarticular regionis a feasibbCompuQVional optionwell-suitedforinvestigation of localtissuestressesin themdioca@ join& It providesausefultoolfor~~~gthemechanicalimplicationsofimprecisenductiond~~~fracturcofthedistal~~ The broadobjectiveof thisresearchis thedevelqent of a we.&verified ccmput&nal modelof themdioca@ joint,which.in amc& with experimental modelspreviouslydeveloped.will he capahleof providing#dance towardrigawsly gnnmdcd&mvements ia distalradius in@articular~turemanagementtechaiques.Aplanestrain~tcelemcntmodcloftheradiocarpalpint~asbeendevelopedandvaifiad throughcompadsonwithpreviouslydevelopedexperimental andanalyticalmod& of thejoist. IIIgeneral,the s&ss distdbutionsobmined withchef~~elementrodelwereconsistentwithresultspreviouslyplblishedforotherarticularpints. ?hemodelinclu&sthedistalmdius and~oprimaryload-bearingcarlxllb((thelunateandthescaphoid).aswellasthcarti thesebones. Themodelholdspomise forprovidingnew insightintothenhukmshipsbetweenjuxtariicular loadtransmission anda&cd surfacegeometryin makcducediatra-a&alartitllre of thedisralradius
THE EFFECT OF HALLUX SESAMOID RESECTION ON
FLEXION MOMENT ARMS OF THE MTP JOINT Rhonda L. Aper, Charles L. Saltzman, and Thomas D. Brown Departments of Orthopaedic Surgery and Biomedical Engineering, The University of Iowa, Iowa City, IA 52242, USA. Intrinsic disorders of the great toe sesamoids (e.g., fracture, osteochondritis, avascular necrosis) can become a chronic source of considerable disability. There is no consensus, however, as to the optimal surgical treatment. The wide variation in the treatment of such disorders points to a fundamental lack of understanding of the functional biomechanical significance of the hallux sesamoids. In this study, the functional significance of the hallux sesamoid bones was quantified by measuring the effective tendon moment arm (ETMA) of the flexor hallucis brevis (FHB) force. The intact case was compared with three levels of progressive sesamoid resection: distal half of the medial sesamoid excised, entire medial sesamoid excised, and both the medial and lateral sesamoids excised. The experimental method consisted of applying a known active functional load to the FHB muscle of fresh Frozen cadaver specimens (the great toe being maintained at specific angles of dorsiflexion) while recording corresponding resisting force from three orthogonally mounted transducers. Results showed the ETMAs to decrease significantly (p < 0.05) only with dual excision. The functionally measured ETMA values of the FHB were less than expected, given the overall physical size of the MTP joint. The ETMA values suggest that the true center of rotation is located plantarwards of the geometric center, close to the tendon centroid.