RESUMO
Reliable osteosynthesis of intraarticular fractures depends on lasting interfragmentary compression. Its amount differs in the applied fixation method. The interfragmentary compression of cancellous and cortical lag screws and angle stable locking plates was quantified in an osteoporotic and non-osteoporotic synthetic human bone model.A split fracture of the lateral tibia plateau (AO/OTA type 41-B1.1) was mimicked by an osteotomy in right adult synthetic human tibiae with hard or soft cancellous bone. Specimens were fixed with either two 6.5âmm cancellous, four 3.5âmm cortical lag screws, or 3.5âmm LCP proximal lateral tibia plate preliminary compresed by a reduction clamp (nâ=â5 per group). A pressure sensor film was used to register the interfragmentary compression. One-way analysis of variance (ANOVA) with Bonferroni post hoc correction was performed for statistical analysis (pâ<â0.05).Interfragmentary compression under reduction clamp was 0.59â±â0.12âMPa in the non-osteoporotic and 0.55â±â0.14âMPa in the osteoporotic group. The locking plate itself maintained the compression in non-osteoporotic (0.53â±â0.11âMPa) and osteoporotic bone (0.50â±â0.14âMPa). Four 3.5âmm cortical lag screws provided a compression of 1.69â±â0.65âMPa in non-osteoporotic bone, being not significantly different to the osteoporotic bone group (1.43â±â0.47âMPa, Pâ=â1.0). Two 6.5âmm cancellous lag screws showed a significantly higher compression in non-osteoporotic (2.1â±â0.59âMPa) compared to osteoporotic (0.77â±â0.21âMPa, Pâ<â0.01) bone.Angle stable locking plates maintained the compression preliminarily applied by a reduction clamp. Two 6.5âmm cancellous lag screws are especially suited for non-osteoporotic bone, whereas four 3.5âmm cortical screws exhibited comparable compression in both bone qualities.