Analiza konstrukcije intramedularnog čavla radi utvrđivanja smjernica konstrukcijskih poboljšanja

master's thesis

• Title (english): Design analysis of the intramedullary rod in order to determine the guidelines for design improvement
• Author: Vilim Jakupić
• Mentor: Aleksandar Sušić (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2018-12-08, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; General Mechanical Engineering (Construction)

Abstract

Na tržištu postoji relativno veliki broj različitih konstrukcija intramedularnih čavala. Iako se puno resursa ulaže u razvoj idealne konstrukcije, još uvijek nije postignuta potrebna optimizacija između tehnologičnosti i cijene naspram funkcionalnosti i operativne jednostavnosti. U prvom dijelu ovog rada provedena je usporedba intramedularnih čavala sa drugim unutarnjim fiksatorima. Zaključeno je da su čavli idealni kod primjene u dugim i snažnim kostima, te da imaju velike prednosti zbog operativne jednostavnosti i načina preuzimanja opterećenja. Zatim su opisane i uspoređene različite skupine intramedularnih čavala, te su pomoću brojnih kliničkih istraživanja uspoređene njihove kliničke i funkcionalne karakteristike. Na temelju tih podataka utvrđeni su kritični uvjeti: integritet konstrukcije, cut-out pojave u femoralnoj glavi, kroz kožu i na distalnom kraju. Također su utvrđene i značajke uspješne primjene: smanjenje trajanja operacije i gubitka krvi, spriječavanje rotacije femoralne glave oko lag vijka i osiguranje od urastanja kortikalne kosti u konstrukciju. Prema kritičnim uvjetima i značajkama uspješne primjene, izvedeni su nedostaci pojedinih vrsta konstrukcija i definiran je generalni smjer optimizacije konstrukcije – zadržavanje tehnologičnosti i cijene proizvoda uz optimiranje funkcionalnosti i operativne jednostavnosti. U skladu s tim zahtjevima izrađena su dva koncepta koja su detaljno opisana. Koncepti su uspoređeni metodom potencijala sa referentim konceptom – Troch čavlom tvrtke Instrumentaria d.d. Iterativnim postupkom su najbolje izvedbe funkcija pojedinih koncepata uklopljene u završni koncept koji je detaljno razrađen. Završna konstrukcija donosi potencijalne prednosti u pogledu spriječavanja cut-out efekta zahvaljujući osiguranju oblikom između lag vijka i pločice za zaključavanje, što dodatno potpomaže i konusni oblik vrha lag vijka za glavu femura. Nadalje, operaterski se jednostavnije pozicionira i vadi jer sadrži manji broj dijelova za uvrtanje, a orijentacija pločice je osigurana pozicijama utora u šipka čavla. Zadržana je mogućnost jednostavne tehnologije izrade savijanjem i obradom odvajanjem čestica kako nebi došlo do poskupljenja proizvoda, a izbjegnuti su gumeni dijelovi koje je potrebno navlačiti pri visokim temperaturama. Na kraju je zaključeno da proizvod još mora biti testiran pomoću FEA alata, što je zahtjevan proces s obzirom na složenu dinamiku ljudskog kretanja, te bi takva analiza premašila opseg ovog rada.

Abstract (english)

On the market there is a relatively large number of different constructions of intramedullary nails. Although a lot of resources are being invested in the development of an ideal construction, the required optimization between the technology and the costs versus functionality and operational simplicity has not yet been achieved. In the first part of this paper we’ve compared the intramedullary nails with other internal fixators. It has been concluded that nails are ideal for long and strong bones, and have great advantages over their operational simplicity and the way they are loaded. Different groups of intramedullary nails were then described and compared, and many clinical studies compared their clinical and functional characteristics. Based on this data, critical conditions were defined: structural integrity, cut-out in femoral head, skin and distal end. Successful applications have also been found: reducing the duration of surgery and loss of blood, preventing the femoral head rotation around the lag screw, and securing the cranial bone into the structure. According to the critical conditions and features of successful application, the deficiencies of certain types of constructions were presented and the general direction of the optimization of the structure was defined - maintaining the technology and the price of the products while optimizing functionality and operational simplicity. Two concepts were created in accordance with these requirements, which are described in detail. Concepts were compared through the potential method with the reference concept - Troch nail from Instrumentaria d.d.. With iterative procedure the best performing functions of particular concepts have been incorporated into the final concept that has been elaborated in detail. The final design brings benefits in preventing cut-out effect thanks to the shielding of the shape between the lag screw and the locking plate, which further supports the conical shape of the tip of the lag screw for femoral head. Furthermore, operationally it is positioned and disposed easier as it contains fewer parts for the insertion and the orientation of the plate is secured by the positions of the slots in the nail rod. The possibility of simple production technology by bending and separating particles has been retained so that there would be no price increase of the product, and rubber parts that need to be tightened at high temperatures were avoided. Finally, the product still needs to be tested by using FEA tools, which is a demanding process in respect to the complex dynamics of human motion and it exceeds the scope of this paper.

• Keywords: intramedularni čavao; koncept; optimizacija; konstrukcija
• Keywords (english): intramedullary nail; concept; optimization; construction
• Language: croatian
• URN:NBN: urn:nbn:hr:235:084648
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-22 23:34:58