| Summary: | 碩士 === 長庚大學 === 醫療機電工程研究所 === 99 === Retrograde locked intramedullary nailing has gradually been widely used to treat femoral supracondylar fractures. Because a standard femoral supracondylar nail has unique disadvantages: high price and potentially inducing a femoral shaft stress fracture, it is often replaced by a traditional femoral or tibial locked nail. A biomechanical comparison was therefore made between both traditional locked nails in order to recommend a better one in treating unstable femoral supracondylar fractures.
Sawbone femurs were osteotomized in the femoral supracondylar area. One centimeter of the medial cortex in the proximal fragment was obliquely removed to simulate an unstable fracture without shortening. Specimens were treated with retrograde dynamic traditional femoral locked nails and other , retrograde dynamic traditional tibial locked nails. All specimens were tested with a servohydraulic Material Testing System machine to compare the relative stability. Static compression, dynamic cyclic compression, and static compression to failure were investigated. An extensometer was used to measure displacement of fragments.
The results displacement between both fragments increased following increment of loads in both nails. The load-displacement curve showed nearly linear up to 1,000N for both nails. The femoral nail had a larger stiffness as compared to the tibial nail in both static compression and dynamic cyclic compression; moreover, larger loads in static compression to failure.
Clinically, a traditional femoral locked nail may be more suitable to replace a standard femoral supracondylar nail with a retrograde fashion to treat an unstable femoral supracondylar fracture.
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