Hungarian Society of Biomechanics: E-Journals / Magyar Biomechanikai Társaság
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Early surgical treatment of scaphocephalia
Get PDFCélkitűzés: A scaphocephalia korai kezelése során szerzett tapasztalatainkat ismertetjük műtéti technikánk bemutatásával.Betegek és módszerek: Száznyolcvan scaphocephaliás gyermek adatait dolgoztuk fel. Hat hónapos kor alatt teljes rekonstrukciót végeztünk egy ülésben. Ez biparietalis cranitomiát, occipitalis decompressziót és az antero-posterior átmérő megrövidítését foglalta magában. Az egy évesnél idősebb gyermekeknél biparietalis decompressziót és az individualis anatómiai helyzettől függően occipitalis és/vagy frontalis bemetszéseket végeztünk.Eredmények: A hat hónapos kor alatt végzett műtétek után megfelelő kozmetikai eredményt és normális kognitív fejlődést tapasztaltunk. Lényeges sebészi morbiditást nem észletünk. Reossifikációt mindössze két esetben jelentkezett az egy éves kor alatti csoportban. Következtetések: A scaphocephalia egy éves kor alatti egy ülésben végzett rekonstrukciója hatékony és biztonságos megoldás. Tapasztalataink szerint a műtét ideális időpontja 4-6 közti életkorra tehető ha a gyermek elérte a hat kilogrammos testsúlyt. DOI: 10.17489/biohun/2011/1/04Objective: The authors report on a technique with assessment of its safety and success rate in cranial reconstruction of scaphocephalic infants less than one year of age. Patients and methods: Results compiled from a series of 180 scaphocephalic patients. In patients younger than six months complete reconstruction could be achieved with the technique that comprised biparietal detachment, occipital decompression and shortening of the antero-posterior diameter in one stage. In older children individual operations have been performed according to anatomy. Results: Both the cosmetic results and the eventual neural development of patients operated on within first six months of life turned out to be excellent. No serious surgical morbidity was observed. Reossification was observed only in two cases under one year.Conclusion: The presented surgical technique is safe and efficient to treat scaphocephaly and ideally recommended during the first six months of life. According to our experience the ideal age is between 4–6 months if the baby reaches six kilograms
The effect of manually controlled dynamization on the lengthened callus – preliminary results
Get PDFThe present study evaluated the radiological changes in normal and dynamized callus after limb lengthening in New Zealand White rabbits. The aims of the study were to create a lengthening device that allows axial controlled manual dynamization and to examine the effect of the maximal amount of dynamization on the healing, lengthened callus.10 male domestic white rabbits were divided into two groups (normal distraction group (NDG) and dynamized distraction group (DDG)). Osteotomy was followed by distraction at the same rate and total length in both groups, but in the dynamized distraction group 1 mm manual dynamization was performed for ten minutes three times a day prior to lengthening. Callus formation and lengthening were analysed on the X-ray pictures and on the three-dimensional CT image respectively. Neither malposition of the pins nor maluninon were found during or after the distraction period. No signifi cant difference was found in the amount of the callus between the NDG and DDG. A lengthening device was created that allows axial ontrolled manual dynamization and prevents instability in the other two axes and our results showed that this large amount of dynamization did not decrease the formation and quality of the callus. DOI: 10.17489/biohun/2010/2/0
The injury of the replaced hip in motor vehicle accidents literature review
Get PDFIn recent years worldwide there has been a considerable increase in the number of middle and older aged patients who undergo total hip replacement, and following surgery they would againlike to live an active life, therefore they take part in everyday traffi c as either drivers or passengers of motor vehicles. In head-on collisions there is a relatively high rate of thigh bone, hip joint and pelvic fractures or traumatic dislocation of the hip joint the so called dashboard injury, in cases like this a replaced hip is exposed to greater dangers. We searched the literature for biomechanical examinations of these special joint circumstances, since the replaced hip can not be comparedto a healthy hip either biologically or mechanically. The reason this is important, because in these patients it might be advisable to fi nd a solution that takes this into consideration during surgery. We could not fi nd literature examining this question on the internet to this day. DOI: 10.17489/biohun/2011/1/05In recent years worldwide there has been a considerable increase in the number of middle and older aged patients who undergo total hip replacement, and following surgery they would againlike to live an active life, therefore they take part in everyday traffi c as either drivers or passengers of motor vehicles. In head-on collisions there is a relatively high rate of thigh bone, hip joint and pelvic fractures or traumatic dislocation of the hip joint the so called dashboard injury, in cases like this a replaced hip is exposed to greater dangers. We searched the literature for biomechanical examinations of these special joint circumstances, since the replaced hip can not be comparedto a healthy hip either biologically or mechanically. The reason this is important, because in these patients it might be advisable to fi nd a solution that takes this into consideration during surgery. We could not fi nd literature examining this question on the internet to this day
Biomechanical testing and finite element analysis of fixator montages
Get PDFAmong the factors determining the stability of external fi xator osteosyntheses the deciding factor is the confi guration of the montage. The authors examined the stability of unilateral andV-forms used in crural fractures together with a Budapest University of Technology task force. They performed osteotomy on cadaver bones and used a total of 12 kinds of montage variations. The various montages were exposed to 5 types of static load, their stability was tested, and fi nite element model experiments were performed. The load tests were evaluated by computer and the charts were compared. It was concluded that unilateral montages are most stable when the pins are placed in the greatest possible distance from each other within one segment and the rods are far from each other. In case of V-frame symmetrically inserted pins should be avoided in thesecond plane for better stability. Finite element model has verifi ed the biomechanical observations. During the biomechanical experiment the authors have gained useful experiences forfurther clinical practice. DOI: 10.17489/biohun/2011/1/06Among the factors determining the stability of external fi xator osteosyntheses the deciding factor is the confi guration of the montage. The authors examined the stability of unilateral andV-forms used in crural fractures together with a Budapest University of Technology task force. They performed osteotomy on cadaver bones and used a total of 12 kinds of montage variations. The various montages were exposed to 5 types of static load, their stability was tested, and fi nite element model experiments were performed. The load tests were evaluated by computer and the charts were compared. It was concluded that unilateral montages are most stable when the pins are placed in the greatest possible distance from each other within one segment and the rods are far from each other. In case of V-frame symmetrically inserted pins should be avoided in thesecond plane for better stability. Finite element model has verifi ed the biomechanical observations. During the biomechanical experiment the authors have gained useful experiences forfurther clinical practice
Is there any reality to the reverse kapandji operation In the treatment of proximal radioulnar synostosis? Biomechanical measurements
Get PDFThe forearm, wrist and elbow joints in addition to the ligamentous system which holds the two bones together make up a combined joint with complex movement. Within this joint framework, injury at any point can result in profound biomechanical changes leading to functional alterations. Such an alteration is the bony bridge between the radius and ulna which is blocking the rotational movements. Surgical treatment can be instead of the resection of the bridge-callus creating a defect on the radius distally to the synostosis. This leads to a “reverse” Sauvé–Kapandji situation and to the disintegration of the bony frame of the forearm. The authors examined the stabilizing effect of the ligamentous system which holds the framework together, with emphasis on the role of the interosseous membrane. Measurements of rotational motion in various stages in the forearm were performed on fresh cadaver forearm preparations in both intact cases and also following the excision of a proximal segment of the radius. The movements were measured and registered using an Instron 8874 biomechanical material testing machine. In addition to registration, both fi xed and mobile digital recording was done. The stabilizing role of the interosseous membrane in supination was only effective when the radius was of normal length. The excision of the radial segment seriously damaged both the rotational motion and the stability of the wrist. DOI: 10.17489/biohun/2010/2/0
Experimental modelling of the venous muscle pump
Get PDFOne of the most interesting phenomena in the venous circulatory system is the vein pump mechanism in the legs. The veins in this area are surrounded by the calf muscle, which periodically deforms the vein walls and squeezes blood out of the section. Venous valves prevent the bloodfrom backflow. A measuring rig was designed to model and measure the periodic pulsation of the veins. The device contains a chamber containing a collapsible tube. In this paper the diameter of the tube was examined under periodically varying chamber pressure. Pictures were taken of the viscoelastic tube during the pulsation. The diameter as a function of time is calculated and compared with the pressure-time series. Also the operation of the check valves of the measuring rig is observed. The results are presented and discussed. DOI: 10.17489/biohun/2010/2/0
