The role of mechanical stimulation in the enhancement of bone healing

Abstract

The biomechanical environment plays a dominant role in the process of fracture repair. Mechanical signals control biological activities at the fracture site, regulate the formation and proliferation of different cell types, and are responsible for the formation of connective tissues and the consolidation of the fractured bone. The mechanobiology at the fracture site can be easily manipulated by the design and configuration of the fracture fixation construct and by the loading of the extremity (weight-bearing prescription). Depending on the choice of fracture fixation, the healing response can be directed towards direct healing or towards indirect healing through callus formation. This manuscript summarizes the evidence from experimental studies and clinical observations on the effect of mechanical manipulation on the healing response. Parameters like fracture gap size, interfragmentary movement, interfragmentary strain, and axial and shear deformation will be explored with respect to their respective effects on fracture repair. Also, the role of externally applied movement on the potential enhancement on the fracture repair process will be explored. Factors like fracture gap size, type and amplitude of the mechanical deformation as well as the loading history and its timing will be discussed.

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“…The fundamental goals of bone healing are the restoration of mechanical resilience and strength of the bone. Both target mechanical properties, so it is not surprising that the processes involved in tissue differentiation and formation are also primarily regulated by mechanobiological feedback signals [1,34]. To be able to respond to biophysical stimuli, bone cells are coupled in a complex and dynamic way to their extracellular environment, particularly osteocytes form a dense communication network within the bone tissue and perceive the mechanical signals on the bones [25].…”

“…To be able to respond to biophysical stimuli, bone cells are coupled in a complex and dynamic way to their extracellular environment, particularly osteocytes form a dense communication network within the bone tissue and perceive the mechanical signals on the bones [25]. They regulate the survival and activity of bone-building osteoblasts and bone-resorbing osteoclasts [1,35,36]. Additionally, osteocytes "direct" fracture healing through all phases due to mechanical stimuli [1,35].…”

“…They regulate the survival and activity of bone-building osteoblasts and bone-resorbing osteoclasts [1,35,36]. Additionally, osteocytes "direct" fracture healing through all phases due to mechanical stimuli [1,35]. Thus, the process of mechanotransduction regulates both bone remodeling and fracture healing.…”

“…Bone is a living organ that is subject to a continuous modeling and remodeling process throughout its life [1,2]. This process is under complex control and follows the principle first described by Wolff in 1870: form follows function [3].…”

“…After an injury (fracture), bone is one of the few organs that can heal without an inferior connective tissue scar. Bone heals with the emergence of bone tissue with the original (pre-fracture) properties [1,4].…”