The Effect of Bone Quality on the Stability of Ankle Arthrodesis. A Finite Element Study

Abstract

Overall, intact joint surfaces and three-screw fixation, with the lateral and medial screws inserted produced the most stable arthrodesis constructs when bone quality was poor. CLINICAL RELEVANCE. Ankle arthrodeses are technically demanding because of the shape and small size of the talus. Preoperative planning is an absolute necessity to determine placement and number of screws. This study shows that poor bone quality decreases the stability of the arthrodesis constructs, suggesting that an attempt should be made to create the most stable three-screw configuration. Finite element models can be used as an effective preoperative tool for planning screw number and placement.

The discrete nature of trabecular bone microarchitecture affects implant stability

“…Most finite element models of screws in trabecular bone assume bone as being a continuum material (Alonso-Vá zquez et al, 2004;Zampelis et al, 2007). However, it is not clear if such an assumption can be made for local analyses of small endosseous implants in bone.…”

Computational Models of the Foot and Ankle for Pathomechanics and Clinical Applications: A Review

“…FE models of the ankle joint have been developed to investigate effects of inferior tibiofibular syndesmosis injuries and screw fixation treatments on ankle functions, 39,40 to compare the effectiveness among different surgical protocols, 3,5 and subsequently to investigate the effect of bone quality on surgical outcomes. 4 Ankle instability, the stress distribution and the range of motion of the ankle joint were investigated and found to be changed before and after ankle joint fixation. The stress in the screws, which is a factor related to screw failure, was evaluated 24 with the application of approximate loads mimicking normal gait.…”

Computational analyses of small endosseous implants in osteoporotic bone

“…Alonso-Vázquez et al (Alonso-Vázquez et al, 2004a) decided on such an approach and reduced Young's modulus for cortical and trabecular bone in order to analyze the influence of low bone quality on implant stability. The same approach was chosen by Zampelis et al (Zampelis et al, 2007).…”

“…Furthermore, following these principles also allows the analysis of multiple components, whereas the analytical determination of the load transfer to a specific component of such a construct is not possible. Such models can also include multiple bones, as was presented by Alonso-Vázquez et al (Alonso-Vázquez et al, 2004a), who applied a loading case which simulated external torque and dorsiflexion on a model of a tibia and talus, in order to determine the stability of different kinds of implant configurations for ankle arthrodesis. The contact between the tibia and the talus was modeled frictionless, which is a reasonable assumption for synovial joints where friction is very low (Stachowiak et al, 1994).…”