A study of fracture callus material properties: Relationship to the torsional strength of bone

Abstract

This study was designed to quantitate the local material properties of fracture callus during gap healing and to relate these local properties to the torsional strength of bone in a canine model under external fixation. Bilateral tibial transverse osteotomies were performed in 32 dogs and stabilized using unilateral external skeletal fixators with a 2-mm gap. Dogs were divided into four equal groups and euthanized at either 2, 4, 8, or 12 weeks. The torsional properties of one bone of each pair were determined. In both bones of each pair, the indentation stiffness, calcium content, and histomorphometric properties of six sites of periosteal callus, six sites of endosteal callus, four sites of cortical bone, and two sites of gap tissue were determined. Each of the four types of tissue had a specific structural or material property change during the study period. The indentation stiffness of periosteal callus increased up to 8 weeks and then plateaued. Endosteal callus stiffness peaked at 8 weeks and then decreased by 12 weeks. Gap tissue stiffness increased linearly over time. Cortical bone stiffness decreased over time. Indentation stiffness was significantly associated with the calcium content of periosteal callus (R2 = 0.50, p less than 0.0001) and gap tissue (R2 = 0.66, p less than 0.0001). The local stiffnesses of gap tissue and periosteal callus were significantly associated with the maximum torque (gap, R2 = 0.50, p less than 0.0001; periosteal, R2 = 0.34, p less than 0.05) and the torsional stiffness (gap, R2 = 0.44, p less than 0.0001; periosteal, R2 = 0.65, p less than 0.0001) of the bone.(ABSTRACT TRUNCATED AT 250 WORDS)

Biophysical stimulation of bone fracture repair, regeneration and remodelling.

“…The distribution of endochondral ossification and intramembranous ossification depended upon the biologic and biomechanical environment. The transformation from callus to mineralized woven bone occurred early in the healing period and increased its volume to replace cartilage and undifferentiated tissue (Markel et al, 1990). This transformation was responsible for the mechanical strength or the cortical bone as demonstrated by the mechanical indentation results in different regions of the maturing callus in a fracture-healing model (Fig.…”

“…Such operative intervention has also been used in the treatment of fracture non-unions (Ilizarov, 1989;Delloye et al, 1990;Marsh et al, 1992). The most commonly applied technique involves callus distraction.…”

Incorporation of cortical bone allografts and autografts in rats: Expression patterns of mRNAs for the TGF-Bs

“…Using the modified Brine11 hardness value, the current study extended the mechanical analyses into the material properties of the graft itself. This method has several limitations, but is widely used in mechanical studies of bone quality (Markel et al 1990). The main disadvantage of the method is the high variation of bone stiffness properties, even within small regions of interest.…”

Quantification of bone healing: Comparison of QCT, SPA, MRI, and DEXA in dog osteotomies

“…As the gap remodels, it should ultimately regain the calcium content and density of normal cortical bone, and therefore, should correlate strongly with torsional properties of the bone. In contrast, periosteal and endosteal callus is formed to stabilize the bone ends and fill the gap with bone (Beljan et al 1971, Eriksson et al 1989, Sevitt 1980 and early in the course of fracture healing would be expected to be more strongly associated with the torsional properties of the bone (Markel et al 1990a). As the bone heals, periosteal and endosteal callus is resorbed, therefore should be less closely associated with torsional properties later in the course of fracture healing.…”