The "double barrel" free vascularized fibular bone graft

A further modification of the free vascularized fibular bone graft is described in which a transverse osteotomy is made from the anterolateral aspect of the fibular shaft just distal to the entry of the nutrient artery. This produces two vascularized bone struts that may be folded parallel to each other but that remain connected by the periosteum and muscle cuff surrounding the peroneal artery and vein. The proximal strut is vascularized by both a periosteal and an endosteal blood supply, whereas the distal strut is vascularized by a periosteal blood supply alone. This so-called "double barrel" free vascularized fibular graft has been employed in three patients with segmental bone defects of the distal femur and in one patient with adjacent bony defects of the radius and ulna.     

The free thoracoumbilical flap for resurfacing large soft-tissue defects of the lower extremity

Both cadavers and living patients were studied regarding a method to resolve large skin defects with bone exposure in the leg, with long-distance thrombosis of the anterior tibial vessels or posterior tibial vessels resulting from traumatic lesions. Forty-six casting mold specimens of cadaveric legs were investigated. There were rich communication branches among the anterior tibial artery, posterior tibial artery, and fibular artery in the foot and ankle, which complemented each other well. Twenty-six patients with large skin defects with bone exposure in the proximal or middle segment of the leg were admitted to the authors' hospital. Among those patients, 19 demonstrated long-distance thrombosis of the anterior tibial vessels or posterior tibial vessels resulting from traumatic lesions. During treatment, a thoracoumbilical flap based on the inferior epigastric vessels was anastomosed to the distal stump of the anterior tibial vessels or the posterior tibial vessels, with reversed flow. All defects were successfully repaired, with good color and texture matches of the flaps. This method can be used for patients with normal anterior tibial vessels or posterior tibial vessels, normal distal stumps of the injured blood vessels, and good reversed flow. The method has the advantages of dissecting blood vessels in the recipient area during the débridement, not affecting the blood circulation of the injured leg, not sacrificing blood vessels of the opposite leg, and not fixing the patient in a forced posture. The muscles are less bulky in the distal one-third of the leg, and the blood vessels are shallow and can be dissected and anastomosed easily. When the flap is used for reconstruction in the proximal two-thirds of the leg, the blood vessel pedicle of the free flap is at a straight angle, without kinking.     

Multiscale,Converging Defects of Macro-Porosity,Microstructure and Matrix Mineralization Impact Long Bone Fragility in NF1

Bone fragility due to osteopenia, osteoporosis or debilitating focal skeletal dysplasias is a frequent observation in the Mendelian disease Neurofibromatosis type 1 (NF1). To determine the mechanisms underlying bone fragility in NF1 we analyzed two conditional mouse models, Nf1Prx1 (limb knock-out) and Nf1Col1 (osteoblast specific knock-out), as well as cortical bone samples from individuals with NF1. We examined mouse bone tissue with micro-computed tomography, qualitative and quantitative histology, mechanical tensile analysis, small-angle X-ray scattering (SAXS), energy dispersive X-ray spectroscopy (EDX), and scanning acoustic microscopy (SAM). In cortical bone of Nf1Prx1 mice we detected ectopic blood vessels that were associated with diaphyseal mineralization defects. Defective mineral binding in the proximity of blood vessels was most likely due to impaired bone collagen formation, as these areas were completely devoid of acidic matrix proteins and contained thin collagen fibers. Additionally, we found significantly reduced mechanical strength of the bone material, which was partially caused by increased osteocyte volume. Consistent with these observations, bone samples from individuals with NF1 and tibial dysplasia showed increased osteocyte lacuna volume. Reduced mechanical properties were associated with diminished matrix stiffness, as determined by SAM. In line with these observations, bone tissue from individuals with NF1 and tibial dysplasia showed heterogeneous mineralization and reduced collagen fiber thickness and packaging. Collectively, the data indicate that bone fragility in NF1 tibial dysplasia is partly due to an increased osteocyte-related micro-porosity, hypomineralization, a generalized defect of organic matrix formation, exacerbated in the regions of tensional and bending force integration, and finally persistence of ectopic blood vessels associated with localized macro-porotic bone lesions.     

The effect of autologous bone marrow stromal cells differentiated on scaffolds for canine tibial bone reconstruction

Bone marrow contains mesenchymal stem cells that form many tissues. Various scaffolds are available for bone reconstruction by tissue engineering. Osteoblastic differentiated bone marrow stromal cells (BMSC) promote osteogenesis on scaffolds and stimulate bone regeneration. We investigated the use of cultured autologous BMSC on different scaffolds for healing defects in tibias of adult male canines. BMSC were isolated from canine humerus bone marrow, differentiated into osteoblasts in culture and loaded onto porous ceramic scaffolds including hydroxyapatite 1, hydroxyapatite gel and calcium phosphate. Osteoblast differentiation was verified by osteonectine and osteocalcine immunocytochemistry. The scaffolds with stromal cells were implanted in the tibial defect. Scaffolds without stromal cells were used as controls. Sections from the defects were processed for histological, ultrastructural, immunohistochemical and histomorphometric analyses to analyze the healing of the defects. BMSC were spread, allowed to proliferate and differentiate to osteoblasts as shown by alizarin red histochemistry, and osteocalcine and osteonectine immunostaining. Scanning electron microscopy showed that BMSC on the scaffolds were more active and adhesive to the calcium phosphate scaffold compared to the others. Macroscopic bone formation was observed in all groups, but scaffolds with stromal cells produced significantly better results. Bone healing occurred earlier and faster with stromal cells on the calcium phosphate scaffold and produced more callus compared to other scaffolds. Tissue healing and osteoblastic marker expression also were better with stromal cells on the scaffolds. Increased trabecula formation, cell density and decreased fibrosis were observed in the calcium phosphate scaffold with stromal cells. Autologous cultured stromal cells on the scaffolds were useful for healing of canine tibial bone defects. The calcium phosphate scaffold was the best for both cell differentiation in vitro and bone regeneration in vivo. It may be possible to improve healing of bone defects in humans using stem cells from bone marrow.     

Crushed bone grafts and a collagen membrane are not suitable for enhancing cartilage quality in the regeneration of osteochondral defects--an in vivo study in sheep

Hyaline joint cartilage has only a limited potential for self-repair. Some of the published techniques for osteochondral defect therapy try to improve that potential. In this study, it was hypothesised that one of those surgical techniques, the crushed transplanted bone graft together with a collagen membrane, accelerates significantly the reconstruction of the subchondral bone plate and improves the mechanical and histological quality of repaired cartilage in osteochondral defects compared to an empty control defect. In order to test this hypothesis, defects were created in the left knee of 12 sheep and filled either with autologous crushed bone graft or left empty. The animals were sacrificed after 3 (n = 6) and 6 (n = 6) months. No differences were found either macroscopically or histomorphometrically between the bone graft and empty control defects. The biomechanical as well as the histological results of the bone graft defects were inferior to the control defects with inflammatory processes caused either by bone graft or membrane remnants. Based on the results in this sheep model, the filling of subchondral bone defects with compacted cancellous bone should be carefully reconsidered.     

Different effects of oestradiol benzoate and norethisterone on the blood flow and mineral content in rat bones.

In three experiments (2 on females, 1 on males), we determined the blood flow in the tibia and the distal part of the femur, together with cardiac output (by means of 85Sr-microspheres), tibial bone density and tibial ash weight related to bone volume. We found that 1) the bone blood flow always fell significantly after oestradiol benzoate, 2) no change occurred after norethisterone in doses corresponding to those of oestradiol benzoate, but the blood flow showed a tendency to fall after doses one order higher (it decreased significantly in one case only), 3) the density of the tibia and tibial ash weight related to bone volume rose nonsignificantly after oestradiol benzoate, but fell (mostly statistically significantly) after norethisterone. The lowering of the bone mineral indexes in rat bones after norethisterone is a surprising and potentially significant finding requiring further verification.     

Segmental bone replacement via patient‐specific,three‐dimensional printed bioresorbable graft substitutes and their use as templates for the culture of mesenchymal stem cells under mechanical stimulation at various frequencies

The treatment of large segmental bone defects remains a challenge as infection, delayed union, and nonunion are common postoperative complications. A three‐dimensional printed bioresorbable and physiologically load‐sustaining graft substitute was developed to mimic native bone tissue for segmental bone repair. Fabricated from polylactic acid, this graft substitute is novel as it is readily customizable to accommodate the particular size and location of the segmental bone of the patient to be replaced. Inspired by the structure of the native bone tissue, the graft substitute exhibits a gradient in porosity and pore size in the radial direction and exhibit mechanical properties similar to those of the native bone tissue. The graft substitute can serve as a template for tissue constructs via seeding with stem cells. The biocompatibility of such templates was tested under in vitro conditions using a dynamic culture of human mesenchymal stem cells. The effects of the mechanical loading of cell‐seeded templates under in vitro conditions were assessed via subjecting the tissue constructs to 28 days of daily mechanical stimulation. The frequency of loading was found to have a significant effect on the rate of mineralization, as the alkaline phosphatase activity and calcium deposition were determined to be particularly high at the typical walking frequency of 2 Hz, suggesting that mechanical stimulation plays a significant role in facilitating the healing process of bone defects. Utilization of such patient‐specific and biocompatible graft substitutes, coupled with patient’s bone marrow cells seeded and exposed to mechanical stimulation of 2 Hz have the potential of reducing significant volumes of cadaveric tissue required, improving long‐term graft stability and incorporation, and alleviating financial burdens associated with delayed or failed fusions of long bone defects.     

Vascularized bone allografts: in vitro assessment of cell-mediated and humoral responses

The immunologic consequences of transplantation of vascularized bone allografts have not been previously characterized. In this study, knee allografts, both vascularized and nonvascularized, were transplanted from Lewis rats to Brown Norway rats across a strong histocompatibility barrier. A total of 66 transplants and 8 control animals were evaluated. The vascularized knee grafts consisted of 1 cm of proximal tibia and distal femur with a minimal muscular cuff isolated on the femoral vessels, and these were transplanted to a heterotopic, subcutaneous position on the abdominal wall of the recipient rat. Nonvascularized allografts (identical but without anastomoses) were transplanted for comparison. The cell-mediated response was measured by lymphocytotoxicity assay, and the humoral response was measured by cytotoxic antibody assay, both employing 51Cr-labeled target cells. The timing and intensity of the immune response differed according to the type of graft. The vascularized bone allografts generated significant cell-mediated and humoral responses as early as 5 days posttransplant. A significant humoral response in nonvascularized bone allografts was not apparent until day 14, while cell-mediated response in these grafts was variable. These findings were correlated with the histologic appearance of the grafted tissue. Cyclosporine, which was administered to one group of vascularized bone allografts, resulted in the suppression of both types of immune responses. The histologic appearance of this group resembled that of isografts transplanted as controls. The clinical application of vascularized bone allografts may offer significant advantages over nonvascularized allografts in the reconstruction of massive bone defects. Complications such as nonunion, fracture, and collapse of articular segments seen in nonvascularized allograft transplantation may be avoided by preservation of the blood supply to the graft. Characterization of the immune response to vascularized bone allografts may subsequently allow the manipulation of the host and/or graft tissue and promote graft incorporation.     

Fate of donor cells in vascularized bone grafts: identification of systemic chimerism by the polymerase chain reaction

Systemic chimerism, or the movement of cells from a transplanted tissue into host organs, is a phenomenon known to occur in association with development of immunological tolerance in allotransplantation. However, little is known about the fate and movement of cells into or out of autogenous free tissue transfers, including vascularized bone grafts. The purpose of this study was to identify systemic chimerism in vascularized bone grafts by transplantation of a vascularized tibiofibular graft from isogenous (inbred) male Lewis rats to female recipients. Donor (male) cells could be identified in the recipient (female) tissues by semiquantitative polymerase chain reaction analysis for a Y chromosome-specific DNA sequence. Chimerism was assessed at 1, 12, 18, and 24 weeks after transplantation. Competitive polymerase chain reaction study using the specific primers for a Y-chromosome marker ( gene) and an autosomal gene (GAPDH) allowed detection of small amounts of male cells in a large pool of female cells and measurement of their relative proportions as a function of time. Of 19 nonimmunosuppressed recipients, nine animals (47 percent) showed low-level chimerism (<0.1 percent) in the peripheral blood. Nine (47 percent), three (16 percent), and two (11 percent) recipients showed high-level chimerism (>1 percent) in the spleen, liver, and thymus, respectively, at final assessment. Donor cells were detected in all bone grafts and in six contralateral tibial bones (i.e., 67 percent of sampled contralateral tibial bones) at 18 and 24 weeks after transplantation. Twenty-four recipients were immunosuppressed with FK506 (tacrolimus) to suppress reaction to a minor histocompatibility barrier present on the Y chromosome. In this group, 14 animals (58 percent) showed low-level chimerism in peripheral blood and 12 (50 percent), eight (33 percent), and one (4 percent) recipients showed high-level chimerism in the spleen, thymus, and liver, respectively. Transplanted cells were detected in nine contralateral tibial bones (i.e., 60 percent of sampled contralateral tibial bones) at 12 and 18 weeks after surgery. The results indicate that polymerase chain reaction for the Y chromosome is a useful tool for differentiating between donor and recipient cell populations experimentally using sex-mismatched tissues in a rat model. This study demonstrated that systemic chimerism occurs after successful vascularized bone transplantation. Transplanted cells not only survive in the graft but also gradually migrate into the recipient's body.     

Mechanical boundary conditions of fracture healing: borderline indications in the treatment of unreamed tibial nailing

Unreamed nailing favors biology at the expense of the achievable mechanical stability. It is therefore of interest to define the limits of the clinical indications for this method. The extended usage of unreamed tibial nailing resulted in reports of an increased rate of complications, especially for the distal portion of the tibia. The goals of this work were to gain a thorough understanding of the load-sharing mechanism between unreamed nail and bone in a fractured tibia, to identify the mechanical reasons for the unfavorable clinical results, and to identify borderline indications due to biomechanical factors. In a three-dimensional finite element model of a human tibia, horizontal defects were stabilized by means of unreamed nailing for five different fracture locations, including proximal and distal borderline indications for this treatment method. The loading of the bone, the loading of the implant and the inter-fragmentary strains were computed. The findings of this study show that with all muscle and joint contact forces included, nailing leads to considerable unloading of the interlocked bone segments. Unreamed nailing of the distal defect results in an extremely low axial and high shear strain between the fragments. The results suggest that mechanical conditions are advantageous to unreamed nailing of proximal and mid-diaphyseal defects. Apart from biological reasons, clinical problems reported for distal fractures may be due to the less favorable mechanical conditions in unreamed nailing. From a biomechanical perspective, the treatment of distal tibial shaft fractures by means of unreamed nailing without additional fragment contact or without stabilizing the fibula should be carefully reconsidered.     

Treatment of infected tibial nonunion with bone defect using central bone grafting technique

Treatment of infected tibial nonunion with bone defect represents a challenge for every orthopaedic surgeon. Various methods of treatment have been described for nonunions with infection, bone loss or both. One of them is the central bone grafting technique, which is a safe and effective treatment for nonunions of the tibia. The technique involves placement of autogenous cancellous bone from the iliac crest on the anterior surface of the interosseous membrane with the aim of creating a tibiofibular synostosis. We present the results of uncontrolled, retrospective and continuous series of ten patients treated by a central bone grafting technique for infected tibial nonunion with bone loss. Mean follow-up period was 12 (10-15) years. Most injuries were a result of war injuries. Clinically and radiologically confirmed bony healing with total consolidation of the graft was achieved in all patients within a period of 10-12 months without further bone grafting. The newly-formed bone mass was able to fulfil the mechanical and functional demands of everyday life activities. Once again, the central bone grafting technique has shown to be a safe, reliable and effective method of treatment for infected tibial nonunion with bone defect.     

Mandibular reconstruction in the radiated patient: the role of osteocutaneous free tissue transfers

This paper discusses our experience with the second metatarsal and iliac crest osteocutaneous transfers for mandibular reconstruction. The prime indication for this type of reconstruction was for anterior mandibular defects when the patient had been previously resected. Midbody to midbody defects were reconstructed with the metatarsal and larger defects with the iliac crest. In most cases, an osteotomy was done to create a mental angle. The evaluation of speech, oral continence, and swallowing revealed good results in all patients unless lip or tongue resection compromised function. Facial contour was excellent in metatarsal reconstructions. The iliac crest cutaneous flap provided a generous supply of skin for both intraoral reconstruction and external skin coverage but tended to be bulky, particularly when used in the submental area. Thirty three of 36 flaps survived completely. Flap losses were due to anastomosis thrombosis (1), pedicle compression (1), and pedicle destruction during exploration for suspected carotid blowout (1). Ninety three percent of bone junctions developed a solid bony union despite the mandible having had a full therapeutic dose of preoperative radiation. Despite wound infections in 8 patients, and intraoral dehiscence with bone exposure in 12 patients, all but one of these transfers went on to good bony union without infection in the bone graft.     

Fibula free flap: a new method of mandible reconstruction

The fibula was investigated as a donor site for free-flap mandible reconstruction. It has the advantages of consistent shape, ample length, distant location to allow a two-team approach, and low donor-site morbidity. It can be raised with a skin island for composite-tissue reconstruction. Twelve segmental mandibular defects (average 13.5 cm) were reconstructed following resection for tumor, most commonly epidermoid carcinoma. Five defects consisted of bone alone, and four others had only a small amount of associated intraoral soft-tissue loss. Eleven patients underwent primary reconstructions. At least two osteotomies were performed on each graft, and miniplates were used for fixation in 11 patients. Six patients received postoperative radiation, and two patients received postoperative chemotherapy. The flaps survived in all patients. All osteotomies healed primarily. The septocutaneous blood supply was generally not adequate to support a skin island for intraoral soft-tissue replacement. The aesthetic result of the reconstruction was excellent in most patients, particularly in "bone only" defects. There was no long-term donor-site morbidity.     

The inhibition of skeletal changes in a rat burn model with a local muscle flap

The effects of early wound closure using a local muscle flap on the development of periosteal new bone formation in a rat burn model were studied. Following a full-thickness burn to one hind limb, periosteal new bone formation along the tibial diaphysis was measured by the use of the fluorochrome agent calcein and an image-analysis system. Prostaglandin E levels, a known inflammatory mediator, from the bone beneath the burn also were measured. Periosteal new bone formation was inhibited by 50 percent in animals that had debridement and wound closure with a gastrocnemius muscle flap and skin graft on postburn day 2 compared to untreated controls or animals closed with skin grafts only. There was a trend toward reduced prostaglandin E measurements from tibial sections in the early closure group compared to untreated controls. This study demonstrates that early wound closure using a local muscle flap inhibits the periosteal new bone formation which is possibly associated with the inflammation in a rat burn model.     

The interrelationship between compact tissue defect and bone shaft cavity circulation

The intraosseous pressure of tissue fluid, the electrical resistance between electrodes and the parameters of hemodynamics in tibial shaft cavity were measured experimentally. It was established that the occurrence and increase of compact defects led to the enhancement of fluid filtration from capillaries and tissue blood filling, whereas the reduction of compact defects led to hemodynamics parameter decrease. The shunting influence of newly formed regenerate bone capillaries cause an arterial wall elasticity increase and volumetric circulation rate limitation. The filtration-and-resorption balance of bone shaft cavity restored and circulation enhanced after compact defect healing.     

Dexamethasone-loaded hydroxyapatite enhances bone regeneration in rat calvarial defects

A combination of bioceramics and osteogenic factors is potentially useful for bone regeneration applications. In the present study, hydroxyapatite particles (HA) were loaded with dexamethasone (Dex) and then characterized using SEM and drug release study. The bone regeneration ability of Dex-loaded HA (Dex/HA) was investigated in a rat critical size bone defect using digital mammography, multislice spiral-computed tomography (MSCT) imaging, and histological analysis. The HA and Dex/HA showed nano and micro-scale morphology with a nearly homogenous distribution of diameter. In addition, about 90 % of the drug was released from Dex/HA over a period of three days. After 8 weeks of implantation in rat calvarial defects, no sign of inflammation or complication was observed at the site of surgery. According to digital mammography and MSCT, Dex/HA showed the highest bone regeneration in rat bone defects compared to those received drug-free HA. Histological studies confirmed these data and showed osteointegration to the surrounding tissue. Taking all together, it was demonstrated that Dex/HA can be used as an appropriate synthetic graft for bone tissue engineering applications. These newly developed bioceramics can be used as new bone graft substitutes in orthopaedic surgery and is capable of enhancing bone regeneration.     

Embryonic origin and Hox status determine progenitor cell fate during adult bone regeneration

The fetal skeleton arises from neural crest and from mesoderm. Here, we provide evidence that each lineage contributes a unique stem cell population to the regeneration of injured adult bones. Using Wnt1Cre::Z/EG mice we found that the neural crest-derived mandible heals with neural crest-derived skeletal stem cells, whereas the mesoderm-derived tibia heals with mesoderm-derived stem cells. We tested whether skeletal stem cells from each lineage were functionally interchangeable by grafting mesoderm-derived cells into mandibular defects, and vice versa. All of the grafting scenarios, except one, healed through the direct differentiation of skeletal stem cells into osteoblasts; when mesoderm-derived cells were transplanted into tibial defects they differentiated into osteoblasts but when transplanted into mandibular defects they differentiated into chondrocytes. A mismatch between the Hox gene expression status of the host and donor cells might be responsible for this aberration in bone repair. We found that initially, mandibular skeletal progenitor cells are Hox-negative but that they adopt a Hoxa11-positive profile when transplanted into a tibial defect. Conversely, tibial skeletal progenitor cells are Hox-positive and maintain this Hox status even when transplanted into a Hox-negative mandibular defect. Skeletal progenitor cells from the two lineages also show differences in osteogenic potential and proliferation, which translate into more robust in vivo bone regeneration by neural crest-derived cells. Thus, embryonic origin and Hox gene expression status distinguish neural crest-derived from mesoderm-derived skeletal progenitor cells, and both characteristics influence the process of adult bone regeneration.     

The Use of Irradiated Allografts in Reconstruction of Tumor Defects – the Tata Memorial Hospital Experience

A Tissue Bank is a valuable adjunct to tumour management. In bone tumours, the defects produced by ablative surgery can be reconstructed using banked tissue, thereby obviating the donor site morbidity associated with autografts. Allografts are especially useful in large defects or in children where the quantity of available autograft is limited. The use of bone allografts in India has been limited by the availability of good quality, affordable grafts. In this article we share our experience with the use of indigenously produced allografts in limb salvage, as bone graft expanders and as struts. Lyophilised, irradiated bone allografts were morcellised and used in 32 patients. In 21 of these patients the allograft was used in contained cavities. Complete incorporation of the graft was seen between 6-9 months in all the 25 cases available for follow-up. In 4 patients the allograft was layered onto autograft. The allograft incorporated with the host bone in only one of these patients.Struts were used in 9 cases (3 cases complete intercalary segmental defect, 3 cases of hemicortical defects, 2 cases of allograft-prosthesis composite around the hip, 1 case an iliac-crest block was used to stop bleeding from an anterior sacral defect). Of these, no incorporation of the full segment struts was observed in 2 patients who were on chemotherapy and radiotherapy. The sacral defect case was lost to follow-up. All the other struts incorporated with the host bone within 6-9 months. In 5 cases there was sterile postoperative drainage. Overall infection was observed in 4 patients (10%). In one the graft was removed, another settled uneventfully with subsequent incorporation of graft, and two have a persisting sinus but good incorporation. Since radiation and lyophilisation are known to affect the material properties of bone, the grafts were rehydrated in saline for 30 minutes prior to transplantation. Autogenous marrow or autograft was used to provide osteoinductive properties. In selected cases the lyophilised, irradiated bone allografts proved to be clinically useful in the reconstruction of large tumour defects.     

Bipedicled vascularized fibula flap for proximal humerus defect in a child

Vascularized bone transfer is becoming the most important option in the many cases in which durable, long-standing bone reconstruction is needed. The transfer of the vascularized epiphyseal plate, although controversial, is advantageous in cases where future growth is needed (i.e., congenital anomalies and tumor resections in children). The use of the free fibular head flap, based on epiphyseal blood supply augmentation, was reported using the anterior tibial artery, or part of it, as the nutritional vessel. By using both the peroneal artery and the specific branch to the fibular head as a bipedicled free flap, we ensured both long-bone fibula reconstruction and augmented blood supply to the head. We report a case of subtotal resection of the humerus due to osteosarcoma in a child that was reconstructed by this method. A preoperative study was conducted on fresh cadavers to identify the specific pedicle of the fibular head. The biceps femoris tendon was used to better stabilize the shoulder joint. The child recovered well and showed good progress in rehabilitation. On follow-up 1 year postoperatively, the shoulder joint remained limited, but showed no signs of substantial remodeling on x-ray. Good elbow and wrist-hand functions were noted. The child developed a single lung metastasis that was also removed. The question remains if the theoretical advantages in bone remodeling, shoulder stability, and bone growth are worth the extra time of surgery or the possible added donor and recipient site complications.     

Platelet concentrate as an additive to bone allografts: a laboratory study using an uniaxial compression test

Chemical cleaning procedures of allografts are destroying viable bone cells and denaturing osteoconductive and osteoinductive proteins present in the graft. The aim of the study was to investigate the mechanical differences of chemical cleaned allografts by adding blood, clotted blood; platelet concentrate and platelet gel using a uniaxial compression test. The allografts were chemically cleaned, dried and standardized according to their grain size distribution. Uniaxial compression test was carried out for the four groups before and after compacting the allografts. No statistically significant difference was found between native allografts, allografts mixed with blood, clotted blood, platelet concentrate and platelet concentrate gel regarding their yield limit after compaction. The authors recommend to chemical clean allografts for large defects, optimize their grain size distribution and add platelet concentrate or platelet rich plasma for enhancing as well primary stability as well bone ingrowth.