Introduction. Segmental bone defect is a challenging problem. We report our experience of bone transport by hexapod external fixator in patients with segmental defects if the tibia. Method. We report herein 15 patients with segmental bone defect of tibia who completed their treatment protocol. All patients were treated had bone transport with Taylor Spatial Frame from 2012 to 2017. All were treated by the senior author NH. Parameters measured included age, sex, diabetes, smoking, diagnosis, method of fixation prior to treatment use of a free flap, bone defect size, frame-time, external fixation index. Results. Mean age at the time of frame application was 42.7 years. Mean follow-up after frame removal was 23.7 months. Three were diabetic, one smoked and one quit smoking during treatment. Seven had Gustilo-Anderson 3B (47%) and 5 Gustilo-Anderson 3A (33%) open fractures. Three (20%) had closed fractures. Nine (60%) had internal fixation with plate in eight and IM nail in one. Ten patients (67%) had soft tissue defect that required a free flap in seven, local flap in two and skin graft in one. Mean transport was 62 mm. Mean external fixator time and latency were 350.1 and 12 days, respectively. Mean External fixator, distraction and maturation indices were 2.1, 0.52 and 1.43 month per centimeter, respectively. Ten Extra- procedures were required in 7 patients. There were no docking site procedures, non-union of regenerate, adjunctive stabilization after frame removal, recurrence of bone infection and recurrence of deformity. Conclusions. Segmental resection and transport by TSF is an effective method to achieve length, alignment and eradicate infection. Although our cohort had longer external fixator indices than similar studies, the complication rate was low

The Masquelet or induced membrane technique (IMT) is a two-stage surgical procedure used for the treatment of segmental bone defects. In this technique, the defect is first filled with a polymethyl methacrylate (PMMA) spacer, which triggers the formation of a membrane that will encapsulate the defect. During the second surgery, the spacer is carefully removed and replaced by autologous bone graft while preserving the membrane. This membrane is vascularized, contains growth factors, and provides mechanical stability to the graft, all of which are assumed to prevent graft resorption and promote bone healing.

The technique is gaining in popularity and several variations have been introduced in the clinical practice. For instance, orthopaedic surgeons now often include antibiotics in the spacer to treat or prevent infection. However, the consequences of this approach on the properties of the induce membrane are not fully understood. Accordingly, in a small animal model, this study aimed to determine the impact on the induced membrane of impregnating spacers with antibiotics frequently used in the IMT.

We surgically created a five-mm segmental defect in the right femur of 25 adult male Sprague Dawley rats. The bone was stabilized with a plate and screws before filling the defect with a PMMA spacer. Animals were divided into five equal groups according to the type and dose of antibiotics impregnated in the spacer: A) no antibiotic (control), B) low-dose tobramycin (1.2 g/40 g of PMMA), C) low-dose vancomycin (1 g/40 g of PMMA), D) high-dose tobramycin (3.6 g/40 g of PMMA), E) high-dose vancomycin (3 g/40 g of PMMA). The animals were euthanized three weeks after surgery and the induced membranes were collected and divided for analysis. We assessed the expression of selected genes (Alpl, Ctgf, Runx2, Tgfb1, Vegfa) within the membrane by quantitative real-time PCR. Moreover, frozen sections of the specimens were used to quantify vascularity by immunohistochemistry (CD31 antigen), proliferative cells by immunofluorescence (Ki-67 antigen), and membrane thickness. Microscopic images of the entire tissue sections were taken and analyzed using FIJI software. Finally, we measured the concentration of vascular endothelial growth factor (VEGF) in the membranes by ELISA.

No significant difference was found among the groups regarding the expression of genes related to osteogenesis (Alpl, Runx2), angiogenesis (Vegfa), or synthesis of extracellular matrix (Ctgf, Tgfb1) (n = four or five). Similarly, the density of proliferative cells and blood vessels within the membrane, as well as the membrane thickness, did not vary substantially between the control, low-dose, or high-dose antibiotic groups (n = four or five). The concentration of VEGF was also not significantly influenced by the treatment received (n = four or five).

The addition of tobramycin or vancomycin to the spacer, at the defined low and high doses, does not significantly alter the bioactive characteristics of the membrane. These results suggest that orthopaedic surgeons could use antibiotic-impregnated spacers for the IMT without compromising the induced membrane and potentially bone healing.

Purpose

Angiogenesis and osteogenesis are essential for bone growth, fracture repair, and bone remodeling. VEGF has an important role in bone repair by promoting angiogenesis and osteogenesis. In our previous study, endothelial progenitor cells (EPCs) promoted bone healing in a rat segmental bone defect as confirmed by radiological, histological and microCT evaluations (Atesok, Li, Schemitsch 2010); EPC treatment of fractures resulted in a significantly higher strength by biomechanical examination (Li, Schemitsch 2010). In addition, cell-based VEGF gene transfer has been effective in the treatment of segmental bone defects in a rabbit model (Li, Schemitsch et al 2009); Purpose of this study: Evaluation of VEGF gene expression after EPC local therapy for a rat segmental bone defect.

Purpose: The purpose of this study was to compare the effects of two types of stem/progenitor cells on the healing of critical sized bone defects in a rat model. Endothelial Progenitor Cells (EPCs), a novel cell type with previously demonstrated effects on angiogenesis in animal models of vascular disease, were compared to both a control group of no cell therapy, and a treatment group of Mesenchymal Stem Cells (MSCs). The hypothesis was that EPCs would demonstrate both superior bone healing and angiogenesis, when compared to the control group and MSC group.

Method: EPCs and MSCs were isolated from the bone marrow of syngeneic rats by differential culture and grown ex vivo for 10 days. Subsequently the cells were harvested, seeded on a gelfoam scaffold, and implanted into a 5mm segmental defect in a rat femur that had been stabilized with a plate and screws. Bone healing was assessed radiographically and by microCT. Angiogenesis was assessed by histology and physiologically, using laser doppler to assess blood flow in the bone and soft tissues. All animal protocols were approved by and performed in accordance with the St. Michael’s Hospital Animal Care Committee. ANOVA was used to test for significant differences between the groups, and a p-value of < 0.05 was considered statistically significant.

Results: The EPC (n=14) group demonstrated radiographic evidence of healing of the bone defect as early as 2 weeks, and all specimens were radiographically healed at 6 weeks. Both the control group (n=14) and the MSC group (n=14) showed no radiographic evidence of healing at 10 weeks. MicroCT comparison of the EPC group versus the control group showed significantly greater bone volume and density at the defect site (p< 0.001). More blood vessel formation was observed in the EPC group versus the control group on histology at 2 weeks. Laser Doppler assessment showed significantly more soft tissue and bone blood flow at 2 and 3 weeks in the EPC group versus the control group (p=0.021).

Conclusion: The results of this study demonstrate that EPCs are effective as cell-based therapy for healing critical sized bone defects in a rat model. In this model EPCs demonstrated superiority to MSCs with regard to bone healing. In addition, EPCs demonstrated superior angiogenesis over controls in a rat model of fracture healing. These results strongly suggest that EPCs are effective for therapeutic angiogenesis and osteogenesis in fracture healing. There is a clinical need for effective strategies in the management of traumatic bone defects and nonunions. Investigation into the use of MSCs as an effective alternative to autologous bone grafting has failed to translate into clinical use. It is possible that EPCs are more effective at the regeneration of bone in segmental defects because of their synergistic effect on angiogenesis and osteogenesis. Further research into EPC based therapies for fracture healing is warranted.

Adrenomedullin is a peptide hormone that has attracted attention with its proliferative and anti-apoptotic effects on osteoblasts in recent years. We investigated the effect of adrenomedullin on healing of the segmental bone defect in a rat model.

36 Wistar rats were randomly divided in six groups based on follow-up periods and administered dose of adrenomedullin hormone. In each group, a 2 mm bone defect was created at the diaphysis of radius, bilaterally. NaCl solution was administered to sham groups three times a week for 4 and 8 weeks, intraperitoneally. Adrenomedullin was administered to study groups three times a week; 15 µg-4 weeks, 15 µg-8 weeks, 30 µg-4 weeks and 30 µg-8 weeks, respectively. After euthanasia, the segmental defects were evaluated by histomorphometric (new bone area (NBA)) and micro-tomographic (bone volume (BV), bone surface (BS), bone mineral density (BMD)) analysis.

Although 4 and 8 weeks 15 μg administered study groups had higher NBA values than the other study and control groups, histomorphometric analysis did not reveal any statistical difference between the control and study groups in terms of new bone area (p > 0.05). In micro-tomographic analysis, BV was higher in 15 μg – 4 weeks group than 30 μg – 4 weeks group (296.9 vs 208.5, p = 0.003) and BS was lower in 30 μg – 4 weeks than 4 week - control group (695.5 vs 1334.7, p = 0.005) but in overall, no significant difference was found between the control and study groups (p > 0.05). Despite these minor differences in histomorphometric and micro-tomographic criteria indicating new bone formation, BMD values of 15 µg-4 and −8 weeks study groups showed significant increase comparing with the control group (p = 0.04, p = 0.001, respectively).

Adrenomedullin seemed to have a positive effect on BMD at a certain dose (15 µg) but it alone is not considered sufficient for healing of the defect with new bone formation. Further studies are needed to assess its effects on bone tissue trauma.

This study was funded by Hacettepe University Scientific Research Projects Coordination Unit

Aims

The aim of this study was to evaluate the radiological outcome of patients with large bone defects in the femur and tibia who were treated according to the guidelines of the diamond concept in our department (Centre for Orthopedics, Trauma Surgery, and Paraplegiology).

Aim. Segmental bone defects following osteomyelitis in pediatric age group may require specifically designed surgical options. Clinical and radiographic elements dictate the option. Different elements play a role on the surgeon's choice. Among them, the size of the defect, the size and the quality of the bone stock available, the status of the skin envelope, the involvement of the adjacent joint. When conditions occur, vascularized fibula flap may represent a solution in managing defects of the long bones even during the early years of life. Method. A retrospective study, covering the period between October 2013 and September 2015, was done. Fourteen patients, nine males, five females, aged 2–13 years, with mean skeletal defect of 8.6 cm (range, 5 to 14 cm), were treated; the mean graft length was of 8.3 cm. The bones involved were femur (4), radius (4), tibia (3) and humerus (3). In 5 cases fibula with its epiphysis was used, in 5 cases the flap was osteocutaneous and in the remaining 4 cases only fibula shaft was utilized. After an average time of 8 months from eradication of infection, the procedure was carried out and the flap was stabilized with external fixators, Kirschner's wires or mini-plate. No graft augmentation was used. Results. Total limb reconstruction was achieved in 13 of 14 cases. The average integration period was 3.5 months. The mean follow-up period was 20.7 months (range 22–43). Mean time for full weight bearing in reconstructed lower limb was 5.8 months. All patients were walking pain-free and none with a supportive device. The fibular flap with epiphysis had good functional outcomes. A few early and delayed complications were observed. Lengthening through one graft on the forearm was achieved and the radial length restored. Conclusions. In low resource setting, provided that the technical skills and the right equipment are available, reconstruction of segmental bone defects secondary to hematogenous osteomyelitis in children using vascularized fibula flap is a viable option that salvages and restores limb function

Common cell based strategies for treating bone defects require time-consuming and expensive isolation and expansion of autologous cells. We developed a novel expedited technology creating gene activated muscle grafts. We hypothesized that BMP-2 activated muscle grafts provide healing capabilities comparable to autologous bone grafting, the clinical gold standard. Two male, syngeneic Fischer 344 rats served as tissue donors. Muscle tissue was harvested from hind limbs and incubated with an adenoviral vector carrying the cDNA encoding BMP-2. Bone tissue was harvested from the iliac crest. Segmental bone defects were created in the right femora of 12 rats and were filled with either BMP-2 activated muscle tissue or bone grafts. After 8 weeks, femora were evaluated by radiographs, microCT, and biomechanical tests. BMP-2 activated muscle grafts and autologous bone grafts resulted in complete mineralization and healing, as documented by radiographs and microCT. Bone volume in the muscle graft defects (33+/-12mm3) was similar to autologous bone graft defects (39+/-5mm3). Torque at failure of the two groups was statistically indistinguishable (240+/-115 Nmm vs. 232+/-108Nmm). In previous experiments we demonstrated that the large segmental defect model in this study will not heal with either empty defects or non-activated muscle grafts. Our findings therefore demonstrate that BMP-2 gene activation of muscle tissue effectively stimulates defect healing similar to autologous bone grafts

Introduction: One of the most frequently seen complications of structural allograft recontructions are either delayed or nonunion. The effect of the periosteum on union of autoclaved segmental bone grafts were investigated in rabbits. Method: Segmental bone defects, 10 milimeters long, in the middle of the left radius were created in 16 adult rabbits. The resected bones, autoclaved 15 minutes at 120 C and reimplanted and fixed with intramedullary Kirchner wires. In group one, 8 rabbits’ graft-host bone junctions were covered with periosteal fiap and in group two, graft-host bone junctions were deperiostized. The plain X-rays were taken at 2, 4, 6 and 8 weeks. The rabbits were sacrificed at the end of 8 weeks. Specimens were also examined histologically. Results: Both radiological and histological results were evaluated. In group one, the results revealed more callus and healing than group two, and they were found statistically significant. Discussion: Periosteal fiaps are easy to perform and enhances the healing of the graft-host junctions. The periosteal fiap technique is effective on the healing of graft-host bone junctions and this technique will worth applying to structural allografts

Segmental bone defects with complex fractures or chronic infections comprise a very special subset of patients. Modular endoprosthetic reconstruction is an operative solution. Without reconstruction amputation/disarticulation is the likely outcome. Aim of the study was to analyse preliminary results of modular endoprosthetic reconstruction in nonneoplastic limb salvage. 11 patients(9 – distal femoral replacement, 2 – total femoral replacement) underwent salvage reconstruction between January 2005 and March 2008 for chronic periprosthetic infections(6 – single stage revision; 2 – two stage revision) and complex periprosthetic fractures(3) with segmental bone defects. Microbiological and haematological evidence of infection was confirmed in the infection group and treated with concomitant community based antibiotic therapy as per guidance from specialist team. The mean age and follow up were 74.2 years and 27.5 months respectively. No intraoperative complications identified. Average post operative mobilisation was with frame at 5 days, 2 sticks at 2 weeks. 1 patient required plastic surgical intervention at index operation. 1 patient had recurrence of infection. Radiographs at 6, 12 & 24 months showed no changes from immediate post-op. Microbiological and haematological evidence of infection eradication was considered as successful treatment. Knee range of movements averaged full extension to 95 degrees. Oxford knee scores showed maximal improvement in the single stage revision group. We conclude that salvage endoprosthetic reconstruction has provided an oppourtunity to avoid amputation. A significant improvement in overall range of motion, knee scores, pain relief and stability was achieved in this highly complex subset of patients. Multidisciplinary support from plastic surgeons and specialist microbiologists is essential

Introduction. Mesenchymal stem cells (MSCs) are identified by having the ability to differentiate into various tissues and typically used to generate bone tissue by a process of resembling intramembranous ossification, namely by direct osteoblastic differentiation. However, most bones develop by endochondral ossification, namely via remodeling of hypertrophic cartilaginous templates. To date, reconstruction of bone defects by endochondral ossification using mesenchymal stem cell-derived chondrocytes (MSC-DCs) have not been reported. The purpose of this study was to evaluate the effects of the transplantation of MSC-DCs on bone healing in segmental defects in rat femurs. Methods. Segmental bone defects (5, 10, 15-millimeter) were produced in the mid-shaft of the femur of the Fisher 344 rats and stabilised with an external fixator. Bone marrow was aspirated from the rat's femur and tibia at 4 weeks before operation. MSCs were isolated and grown in culture and seeded on a Poly dl-lactic-co glycolic acid (PLGA) scaffold. Subsequently, the scaffold was cultured using chondrogenic inducing medium for 21 days. The characteristics of the PLGA scaffold are radiolucent and to be absorbed in about 4 months. The Treatment Group received MSC-DCs, seeded on a PLGA scaffold, locally at the site of the bone defect, and Control Group received scaffold only. The healing processes were monitored radiographically and studied biomechanically and histologically. Results. 5-millimeter defect model: The bone defects in the Treatment Group healed radiographically with a bridging callus formation at 4 weeks after the procedure. Micro-CT scans showed that newly formed bone volume in the Treatment Group at 16 weeks was 1.5 times larger than that of the unaffected side. Biomechanical testing revealed that the Treatment Group showed more than 100% higher bending strength compared to the unaffected side at 8 weeks after the procedure. Histological examination showed that the implanted scaffold of the Treatment Group were covered with recipient periosteum-derived bridging callus and filled with cancellous bone-like tissues derived from endochondral ossification. Bone marrow was reconstituted at about 16 weeks after the procedure. Immunostaining examination revealed that the Type 2 collagen, that is the main component of cartilage (MSC-DCs) gradually disappeared and the Type 1 collagen became to be stained better by degrees, i.e. bone was formed clearly. 10, 15-millimeter defect model: Morphological changes were equivalent to 5-millimeter defect model, and the speed of bone regeneration did not depend on the size of the defect length. On the other hand, none of the Control Group achieved bone union. Conclusion. The results of this study suggested that ossification mechanism of MSC-DCs was very close to endochondral ossification. The quality, quantity, and speed of ossification overwhelm those of past similar models, and further development to new bone regeneration can be expected using this method. Summary. Transplantation of mesenchymal stem cell-derived chondrocytes (MSC-DCs) surprisingly enhances bone healing in segmental bone defects in rats significantly better than the previously reported similar therapy using MSCs

Purpose: One of the most difficult challenges for orthopaedic surgeons is the management of bone loss resulting in a segmental bone defect. Segmental bone defects are ubiquitously difficult to treat, require multi-phase surgery and have frequent complications. A promising new strategy involves combining tissue engineering techniques with the delivery of biologically active proteins to facilitate bone regeneration. The purpose of this study is twofold:. First, to investigate whether a cylindrical, biodegradable load-bearing scaffold, stabilized with an intramedullary (IM) nail, will facilitate early weight bearing in a critical sized canine defect model. The second objective is to investigate if rhBMP-2, transported by the biodegradable carrier, will enhance bone formation and healing across a critical sized canine defect. Method: A critical size defect of 3 cm was created in the canine tibia by osteotomy. A cylindrical, biodegradable scaffold of (poly) propylene fumarate was inserted into the defect and the tibia was stabilized with a locked intramedullary nail. Half of the scaffolds were impregnated with 300μg rhBMP-2 and half remained as controls. The animals were allowed immediate weight bearing post-operatively. X-rays were obtained post-operatively and at weeks 1, 2, 3, 6, 12, 18, and 24. X-rays were assessed for loss of height, integrity of the scaffold, and presence of bridging callous formation. Results: The animals that received scaffolds treated with rhBMP-2 showed abundant callus formation on X-ray. Partial bridging callus formation in this group was seen at 3 weeks. Complete bridging callus (bridging on 4 cortices) was observed by 6 weeks. These specimens maintained height of the defect and overall length of the tibia. Controls demonstrated minimal callus formation at all time points. By 3 weeks significant loss of defect height was observed. By 6 weeks failure of hardware (breakage of interlocking screws and/or screw loosening) was evident. Conclusion: This study shows that biodegradable scaffolds, treated with rhBMP-2 and implanted in a critical sized defect facilitate bridging callus formation and healing across the defect. This data indicates that biodegradable scaffolds made of (poly) propylene fumarate are suitable carriers for rhBMP-2 while providing initial structural support for weight bearing

Aims

This study was designed to characterize the recurrence incidence and risk factors of antibiotic-loaded cement spacer (ALCS) for definitive bone defect treatment in limb osteomyelitis.

Aim: Bone grafts and bone graft substitutes are often used at radical surgical procedures such as; trauma, congenital anomalies, tumor surgery, bone infections, revision arthroplasty surgery, spinal surgery. However autograft and allograft bone are frequently used, they have some limitations. ABM/P-15 (Pepgen P-15) is a combination of anorganic bovine derived hydroxyapa-tite matrix coupled with a synthetic-cell binding peptide (P-15). This tissue engineered particulate bone replacement graft has been established for the treatment of periodontal osseous defects. The aim of this study is to determine the effect of ABM/P-15 on the healing of a critical sized segmental defect in rat radius. Methods: 36 Wistar rats were used at this study. A critical sized segmental defect was created in each rat radius. 13 defects were filled with ABM/P-15 Flow (putty form), 12 defects were filled with ABM/P-15, and 11 defects were used as a control group. The rats were killed at 10 weeks. The healing of defects was evaluated with radiographic and histological studies. Results: The use of ABM/P-15 and ABM/P-15 Flow were demonstrated improved healing of segmental bone defects in rat radius on radiographic and histological studies compared with control group. Statistical evaluation showed that there were significant differences between control sites, and sites treated with P-15 and P-15 Flow (p< 0.005). The highest radiological and histological grades were achieved by P-15. Osteogenic proliferation was seen at the P-15 group more than P-15 flow. Conclusion: Segmental cortical bone defects may be treated with ABM/P-15 instead of bone allografts, and autografts. According to the radiologic and histological parameters measured in this study, the implantation of ABM/P-15 resulted in optimum healing of the segmental cortical bone defects

Aims

This study describes the use of the Masquelet technique to treat segmental tibial bone loss in 12 patients.

The treatment of infected nonunions is difficult. Antibiotic cement-coated (ACC) rods provide stability as well as delivering antibiotics. We conducted a review of 110 infected nonunions treated with ACC rods. Patients were divided into two groups: group A (67 patients) with an infected arthrodesis, and group B (43 patients) with an infected nonunion in a long bone. In group A, infected arthrodesis, the success rate after the first procedure was 38/67 (57%), 29/67 (43%) required further surgery for either control of infection or non-union. At last follow-up, five patients required amputation, representing a limb salvage rate of 62/67 (93%) overall. In all, 29/67 (43%) presented with a bone defect with a mean size of 6.78 cm (2 to 25). Of those with a bone defect, 13/29 (45%) required further surgery and had a mean size of defect of 7.2 cm (3.5 to 25). The cultures were negative in 17/67 (26%) and the most common organism cultured was methicillin-resistant staphylococcus aureus (MRSA) (23/67, (35%)). In group B, long bones nonunion, the success rate after the first procedure was 26/43 (60%), 17/43 (40%) required further surgery for either control of infection or nonunion. The limb salvage rate at last follow-up was 43/43 (100%). A total of 22/43 (51%) had bone defect with a mean size of 4.7 cm (1.5 to 11.5). Of those patients with a bone defect, 93% required further surgery with a mean size of defect of 5.4 cm (3 to 8.5). The cultures were negative in 10/43 (24%) and the most common organism cultured was MRSA, 15/43 (35%). ACC rods are an effective form of treatment for an infected nonunion, with an acceptable rate of complications.

Cite this article: Bone Joint J 2014; 96-B:1349–54