Mechanical Regulation of Bone Regeneration: Theories, Models, and Experiments

Abstract

How mechanical forces influence the regeneration of bone remains an open question. Their effect has been demonstrated experimentally, which has allowed mathematical theories of mechanically driven tissue differentiation to be developed. Many simulations driven by these theories have been presented, however, validation of these models has remained difficult due to the number of independent parameters considered. An overview of these theories and models is presented along with a review of experimental studies and the factors they consider. Finally limitations of current experimental data and how this influences modeling are discussed and potential solutions are proposed.

Bone fracture healing in mechanobiological modeling: A review of principles and methods

“…A primary limitation, when considering both the mechanical and biological aspects, is that is it necessary to solve a series of PDEs and formulate a FE implementation within an iterative procedure (Isaksson, 2012, Anderson et al, 2014, Betts and Müller, 2014). …”

Recent developments on intramedullary nailing: a biomechanical perspective

“…In the absence of cortical contact and with the use of locking screws, the stiffness of the bone–implant construction is almost exclusively defined by the load transfer through the interlocking screws. This assembly is subjected to a complex physiological loading, which may be analyzed as a combination of three main types of load: pure shear and torsion, which create a nonuniform shear loading within the tissue; axial compression; and bending forces, which result in compression on one side and tension on the other side . As previously mentioned, the screws engaging the bone cortices aim to counteract rotational, axial, and bending forces and stabilize the bone–implant construct.…”

“…As reported by Penzkofer et al ., shear movements at the fracture site may tend to damage the inner cortex and may also produce increased play between the nail and the surrounding bone. With regard to bending loading, it has been shown that it may result in asymmetric callus formation, where healing may be considerably inhibited on the tensile side of the callus and promoted on the compressive side . In the screw‐to‐bone toggling‐reduction methods previously described, the increase in the overall fixation system stiffness constructively reduced unfavorable (e.g., shear and torsion) interfragmentary movements that are detrimental to fracture healing; however, they also reduced the beneficial compression movements at the fracture site.…”

“…Although the concept that bone apposition and removal is a biological stress‐controlled process that was already in place in the 19th century, our modern understanding of the bone's complex healing behavior had a long and conflicting theoretical path, and even now there remain many questions to be answered before the process is fully understood . We believe that, in the future, it will bring a better understanding of the relationship between fracture‐healing biology and mechanics.…”

“…Bone is a remarkable composite tissue with outstanding self‐repair capability, recovering its form without permanent scarring . From all the long bone stabilization techniques invented, intramedullary nailing has evolved in such a successful manner that it has become one of the most recommended procedures among physicians.…”