The Stability And Viscoelasticity Differences Between Classic Uncemented Hip System (LCU) And Anatomic Uncemented Hip System (RIBBED) Implanted Into Femoral Canal In Vitro

Objective： To explore the stability and viscoelasticity differencesbetween the classic uncemented hip prosthesis stem (LCU) and anatomicuncemented hip system (RIBBED) implanted into femoral canal in vitro.Methods: This research included9cadavers,18femurs. All the femurswere divided into three groups randomly, group LCU: the femurs wereimplanted with LCU, group RIBBED: were implanted with RIBBED andContral group: all the femurs remained the initial conditions as controlgroup. The stress relaxation test, creep test and compression test wereconducted in all the three groups. Differences were analyzed from thecollected dates.Results: The results showed that, the stress of femurs implanted withLCU in group LCU declined0.338MPA after7200s. While the stress ofgroup RIBBED declined0.339Mpa at the same time. There is nosignificant difference between the two groups (p>0.05). The stress ofcontrol group declined0.411Mpa and was significantly greater than thegroup A, B (P <0.05). Creep test showed that: the strain of group LCUraised0.039%at7200s, and group RIBBED raised0.038%at the sametime, there was no significant difference between the two groups (P>0.05).The control group’s strain raised0.048%, it was significantly higher thangroup LCU and RIBBED (P<0.05). Compression test showed the average displacement of group LCU was2.03±0.06mm under1.0KN pressure,and group RIBBED was1.83±0.05mm. There was significant thedifference between the two groups (P<0.05).Conclusions: After implanted into femoral canal in vitro, there was nosignificant difference of relaxation property, creep property between theRIBBED uncemented prosthesis and LCU uncemented prosthesis. Butthe compression test showed that RIBBED uncemented prosthesis themore stable than LCU uncemented prosthesis.