A Comparison Of The Conventional AO Plate Versus Mend Anatomical Plate And Compression Bolts In Intraarticular Calcaneus Fractures: A Biomechanical Study In Human Cadavers

Objective：Calcaneal fractures is the most common tarsal bone fracturein the foot, accounting for2%of the adult body fractures, of which70%ofcacaneal fractures are intraarticular fractures, the disabilityyrate rate is morethan20%. Undeniable,The high incidence and disability rate of calcanealfractures caused a severe socio-economic problems. Over100years To date,the study of calcaneal fractures is in-depth and the treatment methodscontinuous improvement, but "calcaneal fracture still failed to solve the frac-ture." In recent years, with the development of imaging technology, Orthopa-edistes have reached a consensus that taking the surgery of the internal fixati-on to treat intraarticular calcaneal fractures. Now the fixation devices availablefor calcaneal fracture are many, including the Y-shaped plate, reconstructionplate, AO plate, shaping plate, percutaneous screw,locking calcaneal plate.But the clinical efficacy of these methods reports are vary. The effect of manyways is not ideal, because early complication nsare more and longtermlegacy foot and ankle are dysfunction.Our hospital use calcaneal anatomic pla-te pressure bolt to treat the intra-articular calcaneal fracture through a smallincision reducing the incidence of complications and sequelae. we through th-e experimental to study the biomechanical properties of calcaneal anatomicalplate and compression bolts and its efficacy in the fixation of intraarticularcalcaneal fractures．Methods： Collection eight pairs of fresh frozen lower limbscadavers,Donor, include12males and4females, aged from22to57yearsold, average48.6years old, left foot10, right foot6. specimens were receivedX-ray examination and bone mineral density test, Confirmed specimensdidnot had fractureestumors, malformations of variation,osteoporosis, etc. Using a random number table the specimens were divided into test and controlgroups, each8feet.Intraarticular calcaneal fractures were created to areproductive Sanders type-Ⅲ calcaneal fracture pattern with osteotomy. Thespecimens were randomly divided into two groups. The calcaneal anatomicalplate and compression bolts group was the experimental group while theconventional AO calcaneus plate group was the control group．Then they werestabilized using either the calcaneal anatomical plate and compression bolts orthe conventional AO calcaneus plate. Radiographs were obtained to assessreduction. Each specimen was then subjected to20N to200N and20N to700N cyclic loading followed by loading to failure in the yield pressure test.Data extracted from the mechanical testing machine were recorded. SPSSstatistical analysis software13.0was used to test for differences in the results.Results：The bone density of the specimens was similar between the twogroups (p=0.39).Uniform Sanders type Ⅲ fractures were successfully createdand tested. The experimental group showed a significant lower the maximumdisplacement,elastic displacement during20to200N cyclic loading and asignificant lower irreversible deformation,the maximum displacement duri-ng20to700N cyclic loading. the experimental group showed a significanthigher elastic displacement during20to700N cyclic loading. the experimen-tal group also showed a significant higher load to failure during the yield pre-ssure test. The different between the irreversible deformation during20to200N cyclic loading and the ultimate displacement during the yield pressure testwere not significant. At the point of failure all specimens failed by loss ofreduction. The force applied to the tibia caused displacement and collapse ofthe posterior facet in both groups. The compression bolt and the screws failedby pivoting in the plate hole, the bolts basically maintained their plate-boltangle, whereas in conventional plates the plate-screw angle changed greatly.Conclusion: The calcaneal anatomical plate and compression bolts isconsidered to outperform the conventional AO plat system with its betterstability and its higher strength of fixation in treating intraarticular calcanealfractures. it is applicable especially to do Early Stage Dirigation. It have great clinical application value.