Inter-trabecular bone formation: a specific mechanism for healing of cancellous bone

Abstract

Background and purposeStudies of fracture healing have mainly dealt with shaft fractures, both experimentally and clinically. In contrast, most patients have metaphyseal fractures. There is an increasing awareness that metaphyseal fractures heal partly through mechanisms specific to cancellous bone. Several new models for the study of cancellous bone healing have recently been presented. This review summarizes our current knowledge of cancellous fracture healing.MethodsWe performed a review of the literature after doing a systematic literature search.ResultsCancellous bone appears to heal mainly via direct, membranous bone formation that occurs freely in the marrow, probably mostly arising from local stem cells. This mechanism appears to be specific for cancellous bone, and could be named inter-trabecular bone formation. This kind of bone formation is spatially restricted and does not extend more than a few mm outside the injured region. Usually no cartilage is seen, although external callus and cartilage formation can be induced in meta­physeal fractures by mechanical instability. Inter-trabecular bone formation seems to be less sensitive to anti-inflammatory treatment than shaft fractures.InterpretationThe unique characteristics of inter-trabecular bone formation in metaphyseal fractures can lead to differences from shaft healing regarding the effects of age, loading, or drug treatment. This casts doubt on generalizations about fracture healing based solely on shaft fracture models.

Establishment of a clinically relevant large animal model to assess the healing of metaphyseal bone

“…Thus, the direct transformation into new bone without any cartilage stage could also be attributed to the good biomechanical stability provided by the locking plate. These results supported previous observations that metaphyseal bone healing occurs through a direct intramembranous bone formation under stable biomechanical conditions (Claes et al, 2009;Sandberg and Aspenberg, 2016;Uhthoff and Rahn, 1981). Furthermore, the presence of the Haversian system, consisting of tightly packed osteons of concentric lamellae at the newly bridged cortical bone area, is typical for a mature sheep compact bone and, also, similar to that of humans (Kalu, 1999;Martiniaková et al, 2007).…”

“…The healing of a diaphyseal fracture of the cortical bone area is mainly characterised by callus formation, with both intramembranous and endochondral ossification, where the amount of callus depends on the type and stability of the fracture fixation (Claes et al, 1995;Claes et al, 1997;Rabie et al, 1996). In contrast, healing at the metaphyseal area occurs mainly through a direct membranous bone formation in the trabecular region, with little or no callus formation (Claes et al, 2011;Sandberg and Aspenberg, 2016;Uhthoff and Rahn, 1981). There are many animal models for diaphyseal fracture healing, whereas only a very few in vivo models for metaphyseal bone healing, particularly in large animals (Alt et al, 2013;Beil et al, 2010;Claes et al, 2009;Claes et al, 2011;Fan et al, 2008;Meyer et al, 2001;Uhthoff and Rahn, 1981).…”

Follow up of MRI bone marrow edema in the treated diabetic Charcot foot – a review of patient charts

“…Water-like MRI lesions feature both, acute focal inflammation with microvascular hyperpermeability (in bone and in uninjured adjoining soft tissues, due to inflammatory cytokines [30]), and chronic focal hyperemia (from newly grown fibrovascular reparative tissue preceding woven bone callus) [30–32]. Histopathology of active-stage Charcot foot has revealed all of these entities [33,34] as part of the physiologic secondary healing of cortical and cancellous bone fractures [27,30], and of reactive adjoining soft-tissue inflammation like tenosynovitis [35,36]. …”

“…The form defined 24 anatomic locations of possible EESC lesions, comprising entire bones as well as bone segments. Compact and cancellous bone was assessed separately, as bone healing differs essentially between cortical and cancellous fractures [27]. EESC as described in the reports on file were abstracted and entered into the form.…”

Time dependent loss of trabecular bone in human tibial plateau fractures

“…Furthermore, TRAP expression has also been associated with osteocytic osteolysis; it remains to be seen if osteocytic osteolysis plays a role in the bone loss observed here. The expression of COL1A1 mRNA, encoding type I collagen, the major bone organic matrix protein, was unchanged, consistent with bone formation being unaffected in each limb at sites distal to the fracture itself and the highly localized nature of cancellous bone fracture repair . HIF1A , a gene associated with either osteoclast activation or inhibition, correlated with Tb.Th in both injured and uninjured sides, underscoring the importance of this transcription factor in bone homeostasis.…”