Structural and cellular features in metaphyseal and diaphyseal periosteum of osteoporotic rats

Neuro-bone tissue engineering: Multiple potential translational strategies between nerve and bone

Numerous tissue regeneration paradigms show evident neurological dependence, including mammalian fingertip, skin, and bone regeneration. The mature skeleton is innervated by an abundant nervous system that infiltrates the developing axial and appendicular bones and maintains the stability of the systemic skeletal system by controlling blood flow, regulating bone metabolism, secreting neurotransmitters, and regulating stem cell behavior. In recent years, neurotization in tissue-engineered bone has been considered as a promising strategy to effectively overcome the challenge of vascularization and innervation regeneration in the central zone of "critical-sized bone defects" that conventional tissue-engineered scaffolds are unable to handle, however, further validation is needed in relevant clinical applications. Therefore, this study reviews the mechanisms by which the nervous system regulates bone metabolism and regeneration through a variety of neurogenic or non-neurogenic factors, as well as the recent progress and design strategies of neuralized tissue-engineered bone, to provide new ideas for further studies on subsequent neural bone tissue engineering. STATEMENT OF SIGNIFICANCE: The interaction of nerve and bone tissue during skeletal development and repair has attracted widespread attention, with emerging evidences highlighting the regulation of bone metabolism and regeneration by the nervous system, but the underlying mechanisms have not been elucidated. Thus, further applications of neuro-bone tissue engineering still needs careful consideration. In this review, we summarize the numerous neurogenic and non-neurogenic factors which are involved in bone repair and regeneration, and further explore the current status of their application and biomaterial design in neuro-bone tissue engineering, and finally discuss the challenge and prospective for neuro-bone tissue engineering to facilitate its further development.

The periosteum: a simple tissue with many faces, with special reference to the antler-lineage periostea

Periosteum is a thin membrane covering bone surfaces and consists of two layers: outer fibrous layer and inner cambium layer. Simple appearance of periosteum has belied its own complexity as a composite structure for physical bone protection, mechano-sensor for sensing mechanical loading, reservoir of biochemical molecules for initiating cascade signaling, niche of osteogenic cells for bone formation and repair, and "umbilical cord" for nourishing bone tissue. Periosteum-derived cells (PDCs) have stem cell attributes: self-renewal (no signs of senescence until 80 population doublings) and multipotency (differentiate into fibroblasts, osteoblasts, chondrocytes, adipocytes and skeletal myocytes). In this review, we summarized the currently available knowledge about periosteum and with special references to antler-lineage periostea, and demonstrated that although periosteum is a type of simple tissue in appearance, with multiple faces in functions; antler-lineage periostea add another dimension to the properties of somatic periostea: capable of initiation of ectopic organ formation upon transplantation and full mammalian organ regeneration when interacted with the covering skin. Very recently, we have translated this finding into other mammals, i.e. successfully induced partial regeneration of the amputated rat legs. We believe further refinement along this line would greatly benefit human health.

Delayed Systemic Treatment with Cannabinoid Receptor 2 Agonist Mitigates Spinal Cord Injury-Induced Osteoporosis More Than Acute Treatment Directly after Injury

Nearly all persons with spinal cord injury (SCI) will develop osteoporosis following injury, and further, up to 50% of all persons with SCI will sustain a fracture during their lives. The unique mechanisms driving osteoporosis following SCI remain unknown. The cannabinoid system modulation of bone metabolism through cannabinoid 1/2 (CB1/2) has been of increasing interest for the preservation of bone mass and density in models of osteoporosis. Using a thoracic vertebral level 8 (T8) complete transection in a mouse model, we performed daily treatment with a selective CB2 receptor agonist, HU308, compared with SCI-vehicle-treated and naïve control animals either immediately after injury for 40 days, or in a delayed paradigm, following 3 months after injury. The goal was to prevent or potentially reverse SCI-induced osteoporosis. In the acute phase, administration of the CB2 agonist was not able to preserve the rapid loss of cancellous bone. In the delayed-treatment paradigm, in cortical bone, HU308 increased cortical-area to total-area ratio and periosteal perimeter in the femur, and improved bone density in the distal femur and proximal tibia. Further, we report changes to the metaphyseal periosteum with increased presence of adipocyte and fat mass in the periosteum of SCI animals, which was not present in naïve animals. The layer of fat increased markedly in HU308-treated animals compared with SCI-vehicle-treated animals. Overall, these data show that CB2 agonism targets a number of cell types that can influence overall bone quality.

Mechanisms Supporting the Use of Beta-Blockers for the Management of Breast Cancer Bone Metastasis

Simple Summary

Bone represents the most common site of metastasis for breast cancer and the establishment and growth of metastatic cancer cells within the skeleton significantly reduces the quality of life of patients and their survival. The interplay between sympathetic nerves and bone cells, and its influence on the process of breast cancer bone metastasis is increasingly being recognized. Several mechanisms, all dependent on β-adrenergic receptor signaling in stromal bone cells, were shown to promote the establishment of disseminated cancer cells into the skeleton. This review provides a summary of these mechanisms in support of the therapeutic potential of β-blockers for the early management of breast cancer metastasis.

Abstract

The skeleton is heavily innervated by sympathetic nerves and represents a common site for breast cancer metastases, the latter being the main cause of morbidity and mortality in breast cancer patients. Progression and recurrence of breast cancer, as well as decreased overall survival in breast cancer patients, are associated with chronic stress, a condition known to stimulate sympathetic nerve outflow. Preclinical studies have demonstrated that sympathetic stimulation of β-adrenergic receptors in osteoblasts increases bone vascular density, adhesion of metastatic cancer cells to blood vessels, and their colonization of the bone microenvironment, whereas β-blockade prevented these events in mice with high endogenous sympathetic activity. These findings in preclinical models, along with clinical data from breast cancer patients receiving β-blockers, support the pathophysiological role of excess sympathetic nervous system activity in the formation of bone metastases, and the potential of commonly used, safe, and low-cost β-blockers as adjuvant therapy to improve the prognosis of bone metastases.

Surgical Technique: Closed Reduction and Percutaneous Pinning of Posterolaterally Displaced Supracondylar Humerus Fractures

Gartland type III posterolateral (IIIB) supracondylar humerus fractures are common among the pediatric population and can lead to concomitant injury, including compromise of the brachial artery and median nerve and long-term deformity, such as cubitus varus. These fractures can be difficult to reduce, and there is little consensus regarding the optimal technique for closed reduction and percutaneous pinning. Here, we discuss the management of Gartland III posterolateral supracondylar humerus fractures, including an in-depth technical description of the methods of operative fixation. We describe a lateral pin-only fixation technique for Gartland III posterolateral supracondylar humerus fractures that uses the intact periosteum during reduction of the distal fragment to assist in realigning the medial and lateral columns anatomically. We also discuss a safe method for placing a medial-based pin if there is persistent rotational instability at the fracture site after placement of the laterally based pins.

Sensory denervation increases potential of bisphosphonates to induce osteonecrosis via disproportionate expression of calcitonin gene-related peptide and substance P

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a serious side effect of systematic administration of bisphosphonates (BPs). Sensory innervation is crucial for bone healing. We established inferior alveolar nerve injury (IANI) and inferior alveolar nerve transection (IANT) models characterized by disorganized periosteum, increased osteoclasts, and unbalanced neuropeptide expression. Zoledronate injection disrupted neuropeptide expression in the IANI and IANT models by decreasing calcitonin gene-related peptide (CGRP) and increasing substance P (SP); associated with this, BRONJ prevalence was significantly higher in the IANT model, followed by the IANI model and the sham control. CGRP treatment significantly reduced BRONJ occurrence, whereas SP administration had the opposite effect. In vitro, RAW 264.7 cells were treated with BPs and then CGRP and/or SP to study changes in zoledronate toxicity; combined application of CGRP and SP decreased zoledronate toxicity, whereas CGRP or SP applied alone showed no effects. These results demonstrate that sensory denervation facilitates the occurrence of BRONJ and that CGRP used therapeutically may prevent BRONJ progression, provided that SP is also present. Further studies are necessary to determine the optimal ratio of CGRP to SP for promoting bone healing and to uncover the mechanism by which CGRP and SP cooperate.

Function study of vasoactive intestinal peptide on chick embryonic bone development

Embryonic bone development is a complicated procedure and modulated by neuro-osteogenic interaction. Vasoactive intestinal peptide (VIP) was first identified as a neural vasodilator and further proved to possess multiple biological functions such as neurotransmitter and immune regulator. However, as a key peptide regulator presented in skeletal nerve fibers, the function of VIP on innervation and early bone development regulation has not fully been uncovered yet. In this study, the chick embryo has been used as an experimental model to address the effect of VIP on embryonic bone development. Our study results confirmed the innervation of peripheral nerve fibers into limb bone tissue, which was revealed by the detection of neurofilament (NF) and class III β-tubulin (TUJ-1) in bone tissue at various developing stages. The VIP mRNA and peptide expression level in bone tissue were also increased upon innervation progress. A chick embryonic chemical sympathectomy model was constructed by exposing chick embryos with neurotoxin 6-OHDA. The 6-OHDA exposure of the early chick embryo caused the reduction of neural crest formation and NF expression. 6-OHDA treatment also inhibited distal limb bone development as well as VIP expression. Furthermore, co-application of VIP with 6-OHDA exposure could rescue the inhibited osteogenesis activity and delayed bone development during embryogenesis. Taken together, these results reveal that VIP played an important role during innervation at early stage of bone development. VIP could restore chemical sympathectomy induced osteogenesis inhibition and bone development impair in chick embryos.

Brain-Derived Acetylcholine Maintains Peak Bone Mass in Adult Female Mice

Preclinical and clinical data support a role of the sympathetic nervous system in the regulation of bone remodeling, but the contribution of parasympathetic arm of the autonomic nervous system to bone homeostasis remains less studied. In this study, we sought to determine whether acetylcholine (ACh) contributes to the regulation of bone remodeling after peak bone mass acquisition. We show that reduced central ACh synthesis in mice heterozygous for the choline transporter (ChT) leads to a decrease in bone mass in young female mice, thus independently confirming the previously reported beneficial effect of ACh signaling on bone mass accrual. Increasing brain ACh levels through the use of the blood brain barrier (BBB)-permeable acetylcholinesterase inhibitor (AChEI) galantamine increased trabecular bone mass in adult female mice, whereas a peripheral increase in ACh levels induced by the BBB-impermeable AChEI pyridostigmine caused trabecular bone loss. AChEIs did not alter skeletal norepinephrine level, and induced an overall increase in osteoblast and osteoclast densities, two findings that do not support a reduction in sympathetic outflow as the mechanism involved in the pro-anabolic effect of galantamine on the skeleton. In addition, we did not detect changes in the commitment of skeletal progenitor cells to the osteoblast lineage in vivo in AChEI-treated mice, nor a direct impact of these drugs in vitro on the survival and differentiation of osteoblast and osteoclast progenitors. Last, ChT heterozygosity and galantamine treatment triggered bone changes in female mice only, thus revealing the existence of a gender-specific skeletal response to brain ACh level. In conclusion, this study supports the stimulatory effect of central ACh on bone mass accrual, shows that it also promotes peak bone mass maintenance in adult mice, and suggests that central ACh regulates bone mass via different mechanisms in growing versus sexually mature mice. © 2020 American Society for Bone and Mineral Research.

Have We Looked in the Wrong Direction for More Than 100 Years? Delayed Onset Muscle Soreness Is, in Fact, Neural Microdamage Rather Than Muscle Damage

According to our hypothesis, delayed onset muscle soreness (DOMS) is an acute compression axonopathy of the nerve endings in the muscle spindle. It is caused by the superposition of compression when repetitive eccentric contractions are executed under cognitive demand. The acute compression axonopathy could coincide with microinjury of the surrounding tissues and is enhanced by immune-mediated inflammation. DOMS is masked by sympathetic nervous system activity at initiation, but once it subsides, a safety mode comes into play to prevent further injury. DOMS becomes manifest when the microinjured non-nociceptive sensory fibers of the muscle spindle stop inhibiting the effects of the microinjured, hyperexcited nociceptive sensory fibers, therefore providing the ‘open gate’ in the dorsal horn to hyperalgesia. Reactive oxygen species and nitric oxide play a cross-talking role in the parallel, interlinked degeneration–regeneration mechanisms of these injured tissues. We propose that the mitochondrial electron transport chain generated free radical involvement in the acute compression axonopathy. ‘Closed gate exercises’ could be of nonpharmacological therapeutic importance, because they reduce neuropathic pain in addition to having an anti-inflammatory effect. Finally, DOMS could have an important ontogenetical role by not just enhancing ability to escape danger to survive in the wild, but also triggering muscle growth.

Comparison of anterior mandible anatomical characteristics between obstructive sleep apnea patients and healthy individuals: a combined cone beam computed tomography and polysomnographic study

PURPOSE

This study aims to evaluate the morphology of the genial tubercle (GT) and lingual foramen (LF) between obstructive sleep apnea (OSA) and non-OSA patients for considerations of mandibular advancement surgery.

METHODS

Cone beam CT records of 198 patients were retrospectively collected and analyzed. Five variables were measured for genial tubercle; anterior mandible thickness (AMT), the distance from the lower incisors to the superior border of the genial tubercle, the distance from the inferior border of the genial tubercle to inferior border of the mandible, the height of GT, and genial tubercle width. Lingual foramen were classified according to the genial tubercle. The frequencies, distances of lingual foramen to alveolar crest, lower border of mandible (LVDL) and diameter of LF were also measured.

RESULTS

Significant differences was found for genial tubercle width, anterior mandible thickness, and the distance of lower mandibular border to the midline lingual foramina between OSA and non-OSA patients (p < 0.05). AMT gets thicker and GT gets narrower in OSA patients (p < 0.05). A linear regression analysis on the apnea hypopnea index with measured anatomical variables showed the LVDL (R = - 0.355*), body mass index (R = 0.254), and age (R = 0.33) showed a statistically significant association (p < 0.05). None of the other variables reached formal significance.

CONCLUSION

LVDL is linearly associated with sleep apnea severity. The variable dimensions and anatomy of genial tubercle as well as lingual foramen for OSA patients suggest the need of 3D preoperative radiological evaluation before genioglossus advancement surgery. Cone beam CT can be a powerful low radiation dose tool both for evaluating the anatomy of the upper airway and mandibular structures at the same time for OSA patients.

Impact of the Autonomic Nervous System on the Skeleton

It is from the discovery of leptin and the central nervous system as a regulator of bone remodeling that the presence of autonomic nerves within the skeleton transitioned from a mere histological observation to the mechanism whereby neurons of the central nervous system communicate with cells of the bone microenvironment and regulate bone homeostasis. This shift in paradigm sparked new preclinical and clinical investigations aimed at defining the contribution of sympathetic, parasympathetic, and sensory nerves to the process of bone development, bone mass accrual, bone remodeling, and cancer metastasis. The aim of this article is to review the data that led to the current understanding of the interactions between the autonomic and skeletal systems and to present a critical appraisal of the literature, bringing forth a schema that can put into physiological and clinical context the main genetic and pharmacological observations pointing to the existence of an autonomic control of skeletal homeostasis. The different types of nerves found in the skeleton, their functional interactions with bone cells, their impact on bone development, bone mass accrual and remodeling, and the possible clinical or pathophysiological relevance of these findings are discussed.

FBXW2 localizes with osteocalcin in bovine periosteum on culture dishes as visualized by double immunostaining

Osteocalcin (OC) is a well-known protein related to bone, however, the role of F-box and WD-40 domain-containing protein 2 (FBXW2) in bone remains unclear. In 2016, the presence of FBXW2 in bovine periosteum was reported. In this study, double immunostaining was used to investigate the relationship between OC and FBXW2. FBXW2 showed tubular structures, and OC showed a similar localization pattern as FBXW2. Double immunostaining findings suggested that FBXW2 tubes were coated with OC. To the author's knowledge, this is the first study to reveal the interaction between OC and FBXW2.

Ischaemia, healing and outcomes in proximal humeral fractures

Interfragmental ischaemia is a prerequisite for the initiation of the inflammatory and immunological response to fracturing of bone.Intrafragmental ischaemia is inevitable: the extent of the initial ischaemic insult does not, however, directly relate to the outcome for healing of the fracture zones and avascular necrosis of the humeral head. The survival of distal regions of fragments with critical perfusion may be the result of a type of inosculation (blood vessel contact), which establishes reperfusion before either revascularization or neo-angiogenesis has occurred.Periosteum has a poorly defined role in fracture healing in the proximal humerus. The metaphyseal periosteal perfusion may have a profound effect, as yet undefined, on the healing of most metaphyseal fractures of the proximal humerus, and may be disturbed further by inadvertent surgical manipulation.The metaphysis can be considered as a 'torus' or ring of bone, its surface covered by periosteum antero- and posterolaterally, through which the tuberosity segments gain perfusion and capsular reflections antero- and posteromedially, through which the humeral head (articular) fragment gains perfusion.The torus is broken in relatively simple primary patterns: a fracture line at the upper surface of the torus is an anatomical 'neck' fracture; a fracture line at the lower surface of the torus is the surgical 'neck' fracture. Secondary fragmentation (through compression and/or distraction) of the torus itself creates complexity for analysis (classification), alters the capacity and outcome for healing (by variable interruption of the fragmental blood supply) and influences interfragmental stability. Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.180005.

Bidirectional communication between sensory neurons and osteoblasts in an in vitro coculture system

Recent studies have revealed that the sensory nervous system is involved in bone metabolism. However, the mechanism of communication between neurons and osteoblasts is yet to be elucidated. In this study, we investigated the signaling pathways between sensory neurons of the dorsal root ganglion (DRG) and the osteoblast-like MC3T3-E1 cells using an in vitro coculture system. Our findings indicate that signal transduction from DRG-derived neurons to MC3T3-E1 cells is suppressed by antagonists of the AMPA receptor and the NK₁ receptor. Conversely, signal transduction from MC3T3-E1 cells to DRG-derived neurons is suppressed by a P2X₇ receptor antagonist. Our results suggest that these cells communicate with each other by exocytosis of glutamate, substance P in the efferent signal, and ATP in the afferent signal.

Periosteum mechanobiology and mechanistic insights for regenerative medicine

Periosteum is a smart mechanobiological material that serves as a habitat and delivery vehicle for stem cells as well as biological factors that modulate tissue genesis and healing. Periosteum's remarkable regenerative capacity has been harnessed clinically for over two hundred years. Scientific studies over the past decade have begun to decipher the mechanobiology of periosteum, which has a significant role in its regenerative capacity. This integrative review outlines recent mechanobiological insights that are key to modulating and translating periosteum and its resident stem cells in a regenerative medicine context.

Resting and injury-induced inflamed periosteum contain multiple macrophage subsets that are located at sites of bone growth and regeneration

Better understanding of bone growth and regeneration mechanisms within periosteal tissues will improve understanding of bone physiology and pathology. Macrophage contributions to bone biology and repair have been established but specific investigation of periosteal macrophages has not been undertaken. We used an immunohistochemistry approach to characterize macrophages in growing murine bone and within activated periosteum induced in a mouse model of bone injury. Osteal tissue macrophages (osteomacs) and resident macrophages were distributed throughout resting periosteum. In tissues collected from 4-week-old mice, osteomacs were observed intimately associated with sites of periosteal diaphyseal and metaphyseal bone dynamics associated with normal growth. This included F4/80⁺Mac-2^-/low osteomac association with extended tracks of bone formation (modeling) on diphyseal periosteal surfaces. Although this recapitulated endosteal osteomac characteristics, there was subtle variance in the morphology and spatial organization of periosteal modeling-associated osteomacs, which likely reflects the greater structural complexity of periosteum. Osteomacs, resident macrophages and inflammatory macrophages (F4/80⁺Mac-2^hi) were associated with the complex bone dynamics occurring within the periosteum at the metaphyseal corticalization zone. These three macrophage subsets were also present within activated native periosteum after bone injury across a 9-day time course that spanned the inflammatory through remodeling bone healing phases. This included osteomac association with foci of endochondral ossification within the activated native periosteum. These observations confirm that osteomacs are key components of both osteal tissues, in spite of salient differences between endosteal and periosteal structure and that multiple macrophage subsets are involved in periosteal bone dynamics.

Control of bone remodeling by the peripheral sympathetic nervous system

The skeleton is no longer seen as a static, isolated, and mostly structural organ. Over the last two decades, a more complete picture of the multiple functions of the skeleton has emerged, and its interactions with a growing number of apparently unrelated organs have become evident. The skeleton not only reacts to mechanical loading and inflammatory, hormonal, and mineral challenges, but also acts of its own accord by secreting factors controlling the function of other tissues, including the kidney and possibly the pancreas and gonads. It is thus becoming widely recognized that it is by nature an endocrine organ, in addition to a structural organ and site of mineral storage and hematopoiesis. Consequently and by definition, bone homeostasis must be tightly regulated and integrated with the biology of other organs to maintain whole body homeostasis, and data uncovering the involvement of the central nervous system (CNS) in the control of bone remodeling support this concept. The sympathetic nervous system (SNS) represents one of the main links between the CNS and the skeleton, based on a number of anatomic, pharmacologic, and genetic studies focused on β-adrenergic receptor (βAR) signaling in bone cells. The goal of this report was to review the data supporting the role of the SNS and βAR signaling in the regulation of skeletal homeostasis.

Bone composition: relationship to bone fragility and antiosteoporotic drug effects

The composition of a bone can be described in terms of the mineral phase, hydroxyapatite, the organic phase, which consists of collagen type I, noncollagenous proteins, other components and water. The relative proportions of these various components vary with age, site, gender, disease and treatment. Any drug therapy could change the composition of a bone. This review, however, will only address those pharmaceuticals used to treat or prevent diseases of bone: fragility fractures in particular, and the way they can alter the composition. As bone is a heterogeneous tissue, its composition must be discussed in terms of the chemical makeup, properties of its chemical constituents and their distributions in the ever-changing bone matrix. Emphasis, in this review, is placed on changes in composition as a function of age and various diseases of bone, particularly osteoporosis. It is suggested that while some of the antiosteoporotic drugs can and do modify composition, their positive effects on bone strength may be balanced by negative ones.

Immunohistochemical and molecular characterization of the human periosteum

Purpose. The aim of the present study was to characterize the cell of the human periosteum using immunohistological and molecular methods. Methods. Phenotypic properties and the distribution of the cells within the different layers were investigated with immunohistochemical staining techniques and RT-PCR, focussing on markers for stromal stem cells, osteoblasts, osteoclasts and immune cells. Results. Immunohistochemical results revealed that all stained cells were located in the cambium layer and that most cells were positive for vimentin. The majority of cells consisted of stromal stem cells and osteoblastic precursor cells. The density increased towards the deeper layers of the cambium. In addition, cells positive for markers of the osteoblast, chondrocyte, and osteoclast lineages were found. Interestingly, there were MHC class II-expressing immune cells suggesting the presence of dendritic cells. Using lineage-specific primer pairs RT-PCR confirmed the immunofluorescence microscopy results, supporting that human periosteum serves as a reservoir of stromal stem cells, as well as cells of the osteoblastic, and the chondroblastic lineage, osteoclasts, and dendritic cells. Conclusion. Our work elucidates the role of periosteum as a source of cells with a high regenerative capacity. Undifferentiated stromal stem cells as well as osteoblastic precursor cells are dominating in the cambium layer. A new outlook is given towards an immune response coming from the periosteum as MHC II positive immune cells were detected.

VEGF and bone cell signalling: an essential vessel for communication?

Vascular endothelial growth factor (VEGF) is an endothelial cell survival factor and is required for effective coupling of angiogenesis and osteogenesis. Although central to bone homeostasis, repair and the pathobiology that affect these processes, the precise mechanisms coupling endothelial cell function within bone formation and remodelling remain unclarified. This review will (i) focus on the potential directionality of VEGF signalling in adult bone by identifying the predominant source of VEGF within the bone microenvironment, (ii) will summarize current VEGF receptor expression studies by bone cells and (iii) will provide evidence for a role for VEGF signalling during postnatal repair and osteoporosis. A means of understanding the directionality of VEGF signalling in adult bone would allow us to most effectively target angiogenic pathways in diseases characterized by changes in bone remodelling rates and enhance bone repair when compromised.

Comparative study between tissue-engineered periosteum and structural allograft in rabbit critical-sized radial defect model

The purpose of this study was to compare the efficacy of tissue-engineered periosteum (TEP) to allgeneic bone in repairing segmental bone defect. TEP was fabricated with osteoinduced rabbit bone marrow mesenchymal stem cells (MSCs) and porcine small intestinal submucosa (SIS). Allogrfats were cryopreserved radial segments of New Zealand Rabbits. Forty-eight radial critical-sized defects (CSD) were bilaterally produced in 24 rabbits. The defects were divided into three groups, group A, TEP implantation, group B, SIS implantation, and group C allograft. Bone defect reconstruction was kinetically analyzed at 4, 8, and 12 weeks by radiographic and histological scoring system. In group A, bone defects were radiographically and histologically healed with mature cortex and marrow cavity by 12 weeks, while none of the defects healed in group B. Group C showed a slow process of creeping substitution with lymphocyte infiltration. Statistical comparison confirmed that group A had a more efficient and rapid bone defect reparation as well as remodelling than Group B and C. In conclusion, TEP is superior to structural allograft in reconstruction of allogenic segmental bone defect. Pure SIS cannot guide bone regeneration in this rabbit model.