What Is the Survival of the Telescope Allograft Technique to Augment a Short Proximal Femur Segment in Children After Resection and Distal Femur Endoprosthesis Reconstruction for a Bone Sarcoma?

BACKGROUND: Large, malignant bone tumors and revision limb salvage procedures often result in the resection of extensive lengths of the involved bone segment, leaving a residual segment of bone that may be too short to support a standard intramedullary stem for endoprosthetic reconstruction. Telescope allografting, in which an allograft is used to augment the remaining bone segment by telescoping it into the residual bone segment, was described for situations in which residual bone stock is insufficient after tumor resection or prosthetic revision. Apart from one study that first described the procedure [15], there are no other studies reporting the outcome of this telescopic concept for restoring bone stock. QUESTIONS/PURPOSES: For patients younger than 18 years who underwent the telescopic allograft technique to augment a short segment of the proximal femur after resection of bone sarcomas who also underwent endoprosthesis reconstruction of the distal femur, we asked: (1) What is the survivorship free from removal of the telescopic allograft and the endoprosthetic stem at 7 years after surgery? (2) What proportion of these reconstructions will heal to the host bone without delayed union or nonunion? (3) What is the functional outcome based on the Musculoskeletal Tumor Society (MSTS) score? METHODS: We retrospectively studied our institutional database and identified 127 patients younger than 18 years who underwent surgery for a primary malignant bone tumor of the distal femur between December 2008 and October 2018. After excluding 16 patients undergoing amputation and rotationplasty and 57 patients undergoing recycled autograft/allograft reconstruction, 54 patients who underwent primary or revision distal femur endoprosthesis reconstruction were identified. Among these patients, we considered 15 patients who underwent telescopic allograft augmentation of the femur for analysis. One patient was lost to follow-up before 2 years but was not known to have died, leaving 14 for analysis at a median (range) 49 months (24 to 136 months) of follow-up. The indications for telescopic allograft augmentation of the femur in our institution were a proximal femur length of less than 120 mm after resection or resection of more than two-thirds of the total length of the femur. Ten of 14 patients underwent telescopic allograft augmentation as a revision procedure (distal femur resorption in five patients, endoprosthesis stem loosening in three patients, implant fracture in one patient, and infection in one patient), and the remaining four patients underwent telescopic allograft augmentation as a primary limb salvage procedure for large malignant bone tumors of the distal femur. The histologic diagnosis in all patients was osteosarcoma. At the time of telescopic allograft augmentation and reconstruction, the median age of the patients was 14 years (7 to 18 years). The size and the type of bone allograft to be used (femoral shaft or proximal femur) was planned before surgery, with consideration of the extent of resection, level of osteotomy, diameter of the host bone at the osteotomy site, and approximate diameter of the endoprosthesis stem to be used. The segment of the cylindrical allograft used for telescoping was thoroughly washed, prepared, and impacted onto the native femur to achieve telescoping and overlap. Serial digital radiographs were performed once a month for the first 6 months after the procedure, every 2 months until 1 year, and then every 6 months thereafter. Two surgeons in the department (at least one of which was involved in the surgery) retrieved and reviewed clinical notes and radiographs to determine the status of the telescopic allograft and endoprosthesis stem. We defined delayed union as radiological union at the osteotomy site more than 6 months after the procedure without additional surgery; we defined nonunion as no radiological evidence of callus formation at the osteotomy site 9 months after the procedure, necessitating additional surgery. The reviewers did not disagree about the definition of healing time. None of the patients missed radiographic follow-up. Kaplan-Meier survivorship free from removal of telescopic allograft and the endoprosthesis stem at 7 years after surgery was estimated. Patient function was assessed using the 1993 version of the MSTS [9], as determined by chart review of the institutional database performed by one of the surgeons from the department. RESULTS: The survivorship free from removal of the telescopic allograft and endoprosthesis stem at 7 years after surgery was 80% (95% confidence interval 22% to 96%). The allograft united with the host bone in 100% (14 of 14) of the patients. Though 21% (3 of 14) had delayed union, no nonunions were seen. The median (range) MSTS score at the final follow-up interval was 27 (22 to 30). CONCLUSION: Although this is a small group of patients, we believe that allograft segments help augment short bone stock of the proximal femur after long-segment resections, and the telescopic technique seems to be associated with a low proportion of nonunion or delayed union, which is one of the most common complications of allografts. Maintaining an adequate length of the proximal femur is important in preserving the hip, and this technique may be especially useful for young individuals who may undergo repeated revision procedures. LEVEL OF EVIDENCE: Level IV, therapeutic study.

The role of intraoperative cell salvage system on blood management in major orthopedic surgeries: a cost-benefit analysis.

INTRODUCTION: The aim of this study was to compare the efficiency and cost of cell salvage systems with allogeneic blood transfusions in patients who had major elective orthopedic surgeries. MATERIALS AND METHODS: Consecutive 108 patients who had intraoperative cell saver (CS) performed routinely constitute the study group. In control group, consecutive 112 patients who were operated without intraoperative CS were investigated. Hemoglobin (Hb) level less than 8 mg/dL was regarded as the absolute transfusion indication. The patients were evaluated for age, gender, body mass index, operation period, mean intraoperative estimated blood loss (EBL), postoperative hemovac drainage volume; preoperative, postoperative first day and discharge Hb levels, allogeneic blood transfusion (ABT) volume, hospitalization and cost parameters. RESULTS: The mean intraoperative EBL was 507 mL in the study group and 576 mL in control group. The mean ABT was 300 mL in the study group and 715 mL in control group. In the study group, intraoperative EBL, ABT usage and hospitalization period were significantly lower compared with the control group (p = 0.009, p = 0.000 and p = 0.000; p < 0.05, respectively). The mean cost was 771 Turkish liras (TL) in the study group and 224 TL in control group. In the study group, the cost was significantly higher than the control group (p = 0.000). The postoperative first day Hb level was significantly higher in the study group (p = 0.010). CONCLUSION: Although CS usage was determined to increase the costs in this study, it significantly decreases intraoperative and postoperative ABT requirements. We believe that the increase in cost may be neglected when the complications and prolonged hospitalization due to ABT usage were regarded.

Assessment of a closed wash system developed for processing living donor femoral heads.

NHS Blood and Transplant Tissue and Eye Services (TES) and Scottish National Blood Transfusion Services Tissues and Cells Directorate (TCD) currently bank whole, frozen femoral head bone from living donors who are undergoing primary hip replacement surgery. When required, the bone is issued to a surgeon still frozen on dry ice (- 79 °C). Consequently, the femoral head bone is not processed, is not sterilised and at the time of issue, it contains donor blood, bone marrow and associated cells. We have previously shown that, cut, shaped and washed bone from deceased donors can be processed to remove up to 99.9% of blood, bone marrow and associated cells (Eagle et al. 2015). However, cut and shaped bone is not suitable for some orthopaedic procedures and some orthopaedic surgeons do not wish to use irradiated bone; therefore in this report, a method has been developed in which whole femoral heads can be washed to remove donor blood and bone marrow components. Processing results in excess of 99% bone marrow component removal-soluble protein, haemoglobin and DNA; the procedure is performed inside a closed system, thereby eliminating the need for terminal sterilisation by irradiation. In addition, uniaxial testing demonstrated no difference in compressive strength between washed and unwashed bone. We suggest that this washed bone may be capable of improving incorporation after grafting without disturbing biomechanical properties of the graft.

Immunoisolation to prevent tissue graft rejection: Current knowledge and future use.

This review focuses on the concept of immunoisolation and how this method has evolved over the last few decades. The concept of immunoisolation came out of the need to protect allogeneic transplant tissue from the host immune system and avoid systemic side effects of immunosuppression. The latter remains a significant hurdle in clinical translation of using tissue transplants for restoring endocrine function in diabetes, growth hormone deficiency, and other conditions. Herein, we review the most significant works studying the use of hydrogels, specifically alginate and poly (ethylene glycol), and membranes for immunoisolation and discuss how this approach can be applied in reproductive biology.

The influence of vascularization of transplanted processed allograft nerve on return of motor function in rats.

Processed nerve allografts have become an alternative to repair segmental nerve defects, with results comparable with autografts regarding sensory recovery; however, they have failed to reproduce comparable motor recovery. The purpose of this study was to determine how revascularizaton of processed nerve allograft would affect motor recovery. Eighty-eight rats were divided in four groups of 22 animals each. A unilateral 10-mm sciatic nerve defect was repaired with allograft (group I), allograft wrapped with silicone conduit (group II), allograft augmented with vascular endothelial growth factor (group III), or autograft (group IV). Eight animals from each group were sacrificed at 3 days, and the remaining animals at 16 weeks. Revascularization was evaluated by measuring the graft capillary density at 3 days and 16 weeks. Measurements of ankle contracture, compound muscle action potential, tibialis anterior muscle weight and force, and nerve histomorphometry were performed at 16 weeks. All results were normalized to the contralateral side. The results of capillary density at 3 days were 0.99% ± 1.3% for group I, 0.33% ± 0.6% for group II, 0.05% ± 0.1% for group III, and 75.6% ± 45.7% for group IV. At 16 weeks, the results were 69.9% ± 22.4% for group I, 37.0% ± 16.6% for group II, 84.6% ± 46.6% for group III, and 108.3% ± 46.8% for group IV. The results of muscle force were 47.5% ± 14.4% for group I, 21.7% ± 13.5% for group II, 47.1% ± 7.9% for group III, and 54.4% ± 10.6% for group IV. The use of vascular endothelial growth factor in the fashion used in this study improved neither the nerve allograft short-term revascularization nor the functional motor recovery after 16 weeks. Blocking allograft vascularization from surrounding tissues was detrimental for motor recovery. The processed nerve allografts used in this study showed similar functional motor recovery compared with that of the autograft.

Durability of down-sized homografts for the reconstruction of the right ventricular outflow tract.

OBJECTIVES: Small-sized homografts are rare but may be required for the reconstruction of the right ventricular outflow tract (RVOT). Down-sizing adult-sized homografts can be an option to overcome the shortage of availability. METHODS: Since 1994, we have been down-sizing adult-sized homografts by excising one cusp. The aim of the study was to analyse the durability of down-sized homografts and compare it with small-sized homografts in a paediatric population. All patients below a body weight of 14 kg were included in the study. The end-point of the study was homograft failure. RESULTS: A total of 152 patients met the inclusion criteria of the study, of which 82 patients (54%) received a down-sized homograft. The median age was 17.1 (0.3-64.8) months and the mean weight 8.4 ± 3.4 kg. Fifty-eight patients (38%) were under 1 year and 10 (6.5%) under 1 month of age at the time of homograft implantation. The mean homograft size of the whole study population was 14.7 ± 2.5 mm and the mean z-score was 1.6 ± 0.9. The median follow-up time was 10 (0.03-19.7) years. Early mortality after homograft implantation was 5% (n = 8), 4 of these patients had received a down-sized homograft. The study population comprised early survivors, that is, 144 patients. During follow-up, a total of 46 homografts failed, 23 in each group, after a mean time of 5.7 ± 4.2 years. Freedom from homograft failure was 94.6 ± 2.6, 87.2 ± 4 and 68.6 ± 6.6% for down-sized homografts and 95.2 ± 2.7, 78.7 ± 5.5 and 61 ± 7% for small-sized homografts at 1, 5 and 10 years, respectively (P = 0.3). Risk factors for homograft failure in the multivariable analysis were a homograft z-score of <1 and age below 1 year at the time of implantation (P = 0.02). CONCLUSION: Down-sized homografts demonstrated a durability similar to that of small-sized homografts. Therefore, down-sizing adult-sized homografts by creating a bicuspid valve to fit into the corresponding RVOT in children with congenital heart defects is an excellent method to overcome the shortage of small-sized homografts.

A New Medical Device Rigeneracons Allows to Obtain Viable Micro-Grafts From Mechanical Disaggregation of Human Tissues.

Autologous graft is considered the gold standard of graft materials; however, this approach is still limited due to both small amount of tissue that can be collected and to reduced cell viability of cells that can be obtained. The aim of this preliminary study was to demonstrate the efficacy of an innovative medical device called Rigeneracons® (CE certified Class I) to provide autologous micro-grafts immediately available to be used in the clinical practice. Moreover, Rigeneracons® is an instrument able to create micro-grafts enriched of progenitors cells which maintain their regenerative and differentiation potential. We reported preliminary data about viability cell of samples derived from different kind of human tissues, such as periosteum, cardiac atrial appendage biopsy, and lateral rectus muscle of eyeball and disaggregated by Rigeneracons®. In all cases we observed that micro-grafts obtained by Rigeneracons® displayed high cell viability. Furthermore, by cell characterization of periosteum samples, we also evidenced an high positivity to mesenchymal cell markers, suggesting an optimal regenerative potential.

Successful orthotopic transplantation of short tracheal segments without immunosuppressive therapy.

OBJECTIVES: Results of tracheal transplantation have been disappointing due to of ischaemia and rejection. It has been experimentally demonstrated that results of tracheal autograft/allograft transplantation were correlated with both graft length and revascularization method. Recently, we demonstrated that heterotopic epithelium-denuded-cryopreserved tracheal allograft (TA) displayed satisfactory immune tolerance. We aimed at evaluating the results of such allografts in orthotopic transplantation according to graft length and prior heterotopic or single-stage orthotopic revascularization in a rabbit model. METHODS: Twenty New Zealand rabbits were used. Six females served as donors. Tracheal mucosa was mechanically peeled off and then the TAs were cryopreserved. Male recipients were divided into three groups receiving: (i) long TA segment with prior heterotopic revascularization (10-12 tracheal rings, n = 3); (ii) average TA segment with single-stage orthotopic revascularization (6-8 tracheal rings, n = 4); (iii) short TA segment with single-stage orthotopic revascularization (4-5 tracheal rings, n = 7). No immunosuppressive therapy was administered. Grafts were assessed bronchoscopically and upon death or sacrifice by macroscopic evaluation, histology and immunohistochemical staining for apoptosis. RESULTS: Four animals were sacrificed from Day 33 to Day 220. The survival time of other recipients was 0-47 days (mean 19.6 ± 16.7 days). Aside from three animals that died from complications, all TA segments had satisfactory stiffness, were well vascularized, showed varying levels of neoangiogenesis and inflammatory infiltration devoid of lymphocytes, and showed evidence of only low levels of apoptosis. Varying degrees of fibroblastic proliferation originating from the lamina propria were observed in the lumen of all TAs and evolved over time into collagenized fibrosis in animals surviving over 45 days. Likewise, cartilage tracheal rings exhibited central calcification deposits, which started on Day 16 and increased over time. Epithelial regeneration was constantly observed. Intense fibroblastic proliferation led to stenosis in all animals from Groups (i) and (ii) but only one of seven animals from Group (iii). CONCLUSIONS: Our results suggest that short segments of epithelium-denuded-cryopreserved TA may be reliable for tracheal transplantation in the rabbit model without problems related to graft stiffness or immune rejection. Before considering clinical applications, investigations should be conducted in larger mammals.

Percutaneous vertebroplasty using fresh frozen allogeneic bone chips as filler.

BACKGROUND: Vertebroplasty is not free from cement related complications. If an allograft is used as a filler, most of them can be averted. METHODS: Forty consecutive cases of osteoporotic vertebral fracture were divided into two groups by self-selection. The study and the control groups underwent vertebroplasty with fresh frozen allogeneic bone chips and bone cement, respectively. Clinical results were assessed at preoperation, postoperative day 1 and months 3, 6, and 12 by 10-grade visual analog scale (VAS), and radiological results were assessed at the same time by vertebral kyphotic angle (VKA) and local kyphotic angle (LKA). The results were compared within and between the groups. Survival function was analyzed. The criteria of an event were clinical or radiological deterioration versus pre-index surgery state. RESULTS: VAS was improved in the study group from 8.4 ± 0.8 to 5.2 ± 1.4, 6.4 ± 1.2, 5.5 ± 2.7, and 3.7 ± 1.4 at postoperative day 1 and months 3, 6, and 12, respectively, and in the control group from 8.4 ± 1.2 to 3.2 ± 1.1, 3.2 ± 1.7, 3.2 ± 2.7, and 2.5 ± 1.7, respectively (within group, p < 0.001; between groups, p < 0.001). VKA was improved in the study group from 18.9° ± 8.0° to 15.2° ± 6.1° (p = 0.046) and in the control group from 14.7° ± 5.2° to 10.3° ± 4.7° (p < 0.001) at postoperative day 1. LKA was not improved in the study group but was improved in the control group from 16.8° ± 11.7° to 14.3° ± 9.6° (p = 0.015). Correction angle was 2.7° ± 4.6°, -7.9° ± 5.3°, -7.2° ± 5.2°, and -7.4° ± 6.3° at postoperative day 1 and months 3, 6, and 12, respectively, in the study group and 4.3° ± 3.7°, 0.7° ± 3.6°, 0.7° ± 4.2°, and 0.1° ± 4.4°, respectively, in the control group. Correction loss was significant in both groups (p < 0.001) and more serious in the study group (p < 0.001). The 6-month survival rate was 16.7% in the study group and 64.3% in the control group (p = 0.003; odds ratio, 5.250). CONCLUSIONS: In treatment of osteoporotic vertebral fracture, fresh frozen allogeneic bone chips are not recommendable as a filler for its worse results than bone cement.

2013. Documento Sevilla de Consenso sobre Alternativas a la Transfusión de Sangre Alogénica. Actualización del Documento Sevilla / The 2013 Seville Consensus Document on alternatives to allogenic blood transfusion. An update on the Seville Document

La transfusión de sangre alogénica (TSA) no es inocua, y como consecuencia han surgido múltiples alternativas a la misma (ATSA). Existe variabilidad respecto a las indicaciones y buen uso de las ATSA. Dependiendo de la especialidad de los médicos que tratan a los pacientes, el grado de anemia, la política transfusional, la disponibilidad de las ATSA y el criterio personal, estas se usan de forma variable. Puesto que las ATSA tampoco son inocuas y pueden no cumplir criterios de coste-efectividad, la variabilidad en su uso es inaceptable. Las sociedades españolas de Anestesiología y Reanimación (SEDAR), Hematología y Hemoterapia (SEHH), Farmacia Hospitalaria (SEFH), Medicina Intensiva y Unidades Coronarias (SEMICYUC), Trombosis y Hemostasia (SETH) y Transfusiones Sanguíneas (SETS) han elaborado un documento de consenso para el buen uso de la ATSA. Un panel de expertos de las 6 sociedades ha llevado a cabo una revisión sistemática de la literatura médica y elaborado el 2013. Documento Sevilla de Consenso sobre Alternativas a la Transfusión de Sangre Alogénica. Solo se contempla las ATSA dirigidas a disminuir la transfusión de concentrado de hematíes. Se definen las ATSA como toda medida farmacológica y no farmacológica encaminada a disminuir la transfusión de concentrado de hematíes, preservando siempre la seguridad del paciente. La cuestión principal que se plantea en cada ítem se formula, en forma positiva o negativa, como: «La ATSA en cuestión reduce/no reduce la tasa transfusional». Para formular el grado de recomendación se ha usado la metodología Grades of Recommendation Assessment, Development and Evaluation (GRADE) (AU)

Since allogeneic blood transfusion (ABT) is not harmless, multiple alternatives to ABT (AABT) have emerged, though there is great variability in their indications and appropriate use. This variability results from the interaction of a number of factors, including the specialty of the physician, knowledge and preferences, the degree of anemia, transfusion policy, and AABT availability. Since AABTs are not harmless and may not meet cost-effectiveness criteria, such variability is unacceptable. The Spanish Societies of Anesthesiology (SEDAR), Hematology and Hemotherapy (SEHH), Hospital Pharmacy (SEFH), Critical Care Medicine (SEMICYUC), Thrombosis and Hemostasis (SETH) and Blood Transfusion (SETS) have developed a Consensus Document for the proper use of AABTs. A panel of experts convened by these 6 Societies have conducted a systematic review of the medical literature and have developed the 2013 Seville Consensus Document on Alternatives to Allogeneic Blood Transfusion, which only considers those AABT aimed at decreasing the transfusion of packed red cells. AABTs are defined as any pharmacological or non-pharmacological measure aimed at decreasing the transfusion of red blood cell concentrates, while preserving patient safety. For each AABT, the main question formulated, positively or negatively, is: "Does this particular AABT reduce the transfusion rate or not?" All the recommendations on the use of AABTs were formulated according to the Grades of Recommendation Assessment, Development and Evaluation (GRADE) methodology (AU)

[Detailed methodological recommendations for the treatment of Clostridium difficile-associated diarrhea with faecal transplantation]. / Módszertani ajánlás a Clostridium difficile fertozéshez asszociált hasmenés széklettranszplantációval történo kezeléséhez.

The incidence of Clostridium difficile associated enteral disease shows dramatic increase worldwide, with appallingly high treatment costs, mortality figures, recurrence rates and treatment refractoriness. It is not surprising, that there is significant interest in the development and introduction of alternative therapeutic strategies. Among these only stool transplantation (or faecal bacteriotherapy) is gaining international acceptance due to its excellent cure rate (≈92%), low recurrence rate (≈6%), safety and cost-effectiveness. Unfortunately faecal transplantation is not available for most patients, although based on promising international results, its introduction into the routine clinical practice is well justified and widely expected. The authors would like to facilitate this process, by presenting a detailed faecal transplantation protocol prepared in their Institution based on the available literature and clinical rationality. Officially accepted national methodological guidelines will need to be issued in the future, founded on the expert opinion of relevant professional societies and upcoming advances in this field.

The TheraCyte™ device protects against islet allograft rejection in immunized hosts.

Clinically, many candidates for islet transplantation are already immunized, which increases their risk of graft rejection. Encapsulation of pancreatic islets using the TheraCyte™ device has been shown to protect against allograft rejection in nonimmunized recipients. However, the capacity of the TheraCyte™ device to prevent rejection in immunized recipients has not yet been studied. In this study, the protective capacity of the TheraCyte™ device was evaluated in an allogeneic rat model. Lewis rats were used as islet donors, and nonimmunized (control) and alloimmunized, diabetic Wistar-Furth (WF) rats were used as recipients. Graft survival was shorter in immunized recipients than in nonimmunized recipients (mean survival, 5.3 ± 2.7 and 9.3 ± 1.6 days, respectively, p < 0.01) when nonencapsulated islets were transplanted under the kidney capsule. When islets were transplanted into the TheraCyte™ device, graft function was maintained during the 6-month study period in both immunized and nonimmunized rats. In oral glucose tolerance tests performed at 1 month after transplantation, both groups had similar insulin and blood glucose levels indicating similar metabolic functions. Volume densities and absolute volumes of tissue inside the devices 6 months after transplantation were also comparable between the two groups, indicating that both groups maintained similar amounts of endocrine tissue. A higher number of IFN-γ-producing CD8+ T-cells were detected in immunized WF rats compared to control WF rats transplanted with encapsulated islets. This suggests that donor-specific alloreactivity in recipient rats was sustained throughout the study period. This study suggests that the TheraCyte™ device protects islet allografts also in immunized recipients. Our results further highlight the potential for using macroencapsulation to avoid immunosuppressive therapy in clinical islet transplantation.

Recuperador celular / No disponible

Los recuperadores de sangre son unos instrumentos usados cada vez más en los quirófanos. Resultan especialmente útiles en las intervenciones donde existe mucho riesgo de sangrado y las necesidades transfusionales son elevadas. En pediatría tienen una gran importancia en intervenciones complicadas con la finalidad de evitar transfusiones alogénicas (sangre obtenida de donantes). La aplicación del recuperador de sangre en el campo quirúrgico es muy simple y de fácil utilización. Se trata de una cánula de aspiración que recoge la sangre que queda libre, trasladándola a una centrifugadora donde se filtra y lava, almacenándola en una bolsa de recogida para su posterior infusión. La sangre es de gran calidad y contiene un hematocrito más elevado que la procedente de banco (AU)

The blood retrievers are instruments increasingly used in operating rooms. They are especially useful in operations where there is a high risk of bleeding and transfusion requirements are high. In paediatrics is of great importance in complex interventions in order to avoid allogeneic transfusion (blood collected from donors). The implementation of the recovery of blood in the surgical field is very simple and easy to use. This is a suction tube that collects the blood that is free, transferring it to a centrifuge where it is filtered and washed, stored in a blood collection bag for subsequent infusion. The blood is of high quality and contains a high hematocrit blood from the bank (AU)

[Discussion on the key aspects of risk control and problems of quality management systems for allogeneic bone products].

From the view of the potential risks of allogeneic bone products in clinical use. the key aspects of risk control and quality management for these products are discussed, as well as the general problems existing in the quality management system of their production enterprises in China are briefly introduced.

Bioactive and osteoinductive bone graft substitutes: definitions, facts and myths.

The use of artificial bone grafts has been developed over recent years and is expected to increase further, for some indications even replacing the gold standard, autograft, in trauma and reconstructive surgery. However, the effectiveness of these materials is still a subject of debate, mostly because of unclear definitions or limited market surveillance. In this overview several facts and myths regarding bone-graft substitutes are summarized.

The use of bone-graft substitutes in large bone defects: any specific needs?

INTRODUCTION: The gold standard for restoring bone defects is still considered to be autologous bone grafting. However, clinical benefits are not guaranteed and donor-site complications and morbidity is not infrequent. Research is on-going for the development of alternative bone substitutes of both biological and synthetic origin. The purpose of this study was to evaluate the type of materials used and their efficacy for the treatment of large bone defects in traumatology and orthopaedic surgery. MATERIALS AND METHOD: A literature review was carried out of Embase and PubMed databases. Inclusion criteria were articles in English language focusing on the use of bone substitutes in trauma and orthopaedic surgery for the treatment of bone defects and included details on the structural, biological or biomechanical properties of the pure product. Furthermore, based on two clinical challenges, fracture non-union and impaction grafting we elaborated on the use of polytherapy for large bone defects as guided by the diamond concept. RESULTS: All the products indicated in this manuscript possess osteoconductive activities but have different resorption times and biomechanical properties. Bone graft substitute materials are used for a wide range of clinical applications even when the level of clinical evidence is low. The size and location of the defect and the local biological and mechanical environment as well as the biomechanical characteristics of the material determine the type of device that can be implanted in a bone defect. CONCLUSION: Proper assessment of the biological and mechanical environment and accurate patient selection are necessary to judge the extent of therapy the injury warrants. A sound understanding of various aspects of biomaterial properties and their relation and influence towards bone healing is of utmost importance. We suggest the application of polytherapy for the treatment of large bone defects and advocate the use of the diamond concept as a guideline.

A modified technique for dowel fibular strut graft placement and circumferential fusion in the setting of L5-S1 spondylolisthesis and multilevel degenerative disc disease.

BACKGROUND: Traditional techniques for the treatment of isthmic spondylolisthesis pass a fibular dowel graft across the L5-S1 disc by using the anterior portion of the L5 body. OBJECTIVE: To introduce a technique for the treatment of isthmic spondylolisthesis in the setting of multilevel degenerative disc disease in adults. Our modified technique allows us to traverse the L5-S1 disc via the L4-5 disc space thereby treating the degenerated disc at L4-5 simultaneously. METHODS: A standard anterior discectomy was performed on L4-5. Using biplanar fluoroscopy, a Kirschner wire was placed beginning at the anterior third of the L5 superior endplate and ending at S1. An anterior cruciate ligament reamer was used to make a channel for the fibular allograft. Then, a femoral ring allograft was placed in the disc space at L4-5, and standard anterior lumbar interbody fusions were performed at any additional cephalad level(s). Afterward, posterior instrumented fusion was performed to complement the anterior fusion procedure (except at L5), and wide decompression followed. RESULTS: All patients presented with isthmic spondylolisthesis and all had multilevel fusions. The mean slip angle was 32.6 degrees (37.8 degrees preoperatively), and mean lumbar index was 67%. After the procedure, the average endplate-to-dowel angle was 107.1 degrees compared with 134 degrees. All patients had clinical and radiographic evidence of solid fusion without the need for revisions. CONCLUSION: The proposed advantage of our modified technique is twofold. The graft is placed nearly perpendicular to the L5-S1 interface, as it will behave more efficiently with respect to interfragmental compression. Also, surgeons gain access to fuse L4-5 anteriorly and posteriorly.

A first semimanual device for clinical intramuscular repetitive cell injections.

Intramuscular cell transplantation in humans requires so far meticulous repetitive cell injections. Performed percutaneously with syringes operated manually, the procedure is very time consuming and requires a lot of concentration to deliver the cells exactly in the required region. This becomes impractical and inaccurate for large volumes of muscle. In order to accelerate this task, to render it more precise, and to perform injections more reproducible in large volumes of muscle, we developed a specific semimanual device for intramuscular repetitive cell injections. Our prototype delivers very small quantities of cell suspension, homogeneously throughout several needles, from a container in the device. It was designed in order to deliver the cells as best as possible only in a given subcutaneous region (in our case, skeletal muscles accessible from the surface), avoiding wasting in skin and hypodermis. The device was tested in monkeys by performing intramuscular allotransplantations of beta-galactosidase-labeled myoblasts. During transplantations, it was more ergonomic and considerably faster than manually operated syringes, facilitating the cell graft in whole limb muscles. Biopsies of the myoblast-injected muscles 1 month later showed abundant beta-galactosidase-positive myofibers with homogeneous distribution through the biopsy sections. This is the first device specifically designed for the needs of intramuscular cell transplantation in a clinical context.

A review of allograft ophthalmic tissue in eye surgery.

Transplanting human tissue to the front of the eye has been practiced for over 100 years. Contiguous corneal layers may be transplanted separately (lamellar keratoplasty) or together (full thickness or penetrating keratoplasty). The former methods are gaining in popularity, replacing full thickness transplants. Reasons for transplantation and current practice and techniques are described with respect to their impact on vision, and associated adverse events.