Ricardo Rosito

In vItro And In vIvo EvAluAtIon of lyopHIlIzEd BovInE BonE BIoCompAtIBIlIty

INTRODUCTION The use of bone grafts in orthopedic, maxillofacial and dental surgery has been growing. Nevertheless, both fresh autografts and frozen allografts have limitations, and therefore, alternative synthetic or natural biomaterials, such as processed and lyophilized bovine bone graft have been developed. OBJECTIVE To evaluate in vitro and in vivo biocompatibility of lyophilized bovine bone manufactured in a semi-industrial scale, according to a modifical protocol developed by the authors. METHODS Samples of bovine cancellous bone were processed according to a protocol developed by Kakiuchi et al., and modified to process samples of bovine cancellous bone. The following trials were performed: in vitro cytotoxicity, in vivo acute systemic toxicity, in vivo oral irritation potential, in vitro pyrogenic reaction, and bioburden. RESULTS The in vitro evaluation of lyophilized bovine cancellous bone revealed an absence of cytotoxicity in 100% of the samples. Regarding in vivo evaluation of acute systemic toxicity, neither macroscopic abnormalities nor deaths were noted in the animals. Pyrogenicity was not greater than 0.125 UE/ml in any of the samples. The bioburden revealed negative results for microbial growth before sterilization. Regarding the oral irritation potential, in vivo evaluation at 24 and 72 hours showed that the animals had no edema or erythema on the oral mucosa. CONCLUSION The protocol changes established by the authors to prepare lyophilized bovine cancellous bone at a semi-industrial scale is reproducible and yielded a product with excellent biocompatibility.

Prevalence of radiographic markers of femoroacetabular impingement in asymptomatic adults

OBJECTIVE to determine the prevalence of radiographic signs of femoroacetabular impingement (FAI) in asymptomatic adults and correlate them with data from physical examinations. METHODS We conducted a cross-sectional study with 82 asymptomatic volunteers, 164 hips, between 40 and 60 years of age, selected by convenience. They were submitted to anamnesis and clinical examination of the hip, anteroposterior (AP) pelvis radiographs with three incidences, Dunn 45° and Lequesne false profile of each hip, to measure the variables. We measured the alpha angle, anterior offset of the femoral neck, cervical diaphyseal angle, CE angle of Wiberg, acetabular index, Sharp angle, and the crossing, ischial spine and posterior wall signs. RESULTS our sample consisted of 66% women, mean age of 50.4 years. The average alpha angle was 45.10°, SD=8.6. One quarter of the hips showed alpha angle greater than or equal to 50°; among men the prevalence was 34%, and among women, 11%. We found indicative radiographic signs of femoroacetabular impingement in 42.6% of hips, whether femoral or acetabular, and the increased alpha angle was related to the decrease in hip internal rotation (p<0.001). CONCLUSION the radiographic findings of femoroacetabular impingement in asymptomatic patients were frequent in the studied sample. The increase in alpha angle was associated with decreased internal rotation.

Acetabular reconstruction with human and bovine freeze-dried bone grafts and a reinforcement device

BACKGROUND This is a cohort trial (1997–2005) of 49 patients submitted to an acetabular component revision of a total hip arthroplasty, using impacted human and bovine freeze-dried cancellous bone grafts (H&FDBG) and a reinforcement device. OBJECTIVE To compare clinical/radiographic graft incorporation capability between cancellous bone grafts. PATIENTS/METHODS There were two groups: I (n=26) receiving human grafts and II (n=25) receiving bovine grafts. The average follow-up times were 55 and 49 months, respectively. Clinical analysis was based on the Merle d’Aubigné and Postel score, and the radiographic analysis involved an established score based on Conn’s et al. criteria for radiographic bone incorporation. RESULTS No clinical/radiographic differences were found between the groups and both showed an overall rate of 88.5% and 76% of graft incorporation (p=0.424). CONCLUSION The results presented here are comparable to those in the literature with the use of deep-FG. Therefore, cancellous bone grafts can be safely and adequately used in acetabular component revision in total hip arthroplasty.

CARACTERIZAÇÃO FÍSICO-QUÍMICA DO ENXERTO DE OSSO BOVINO LIOFILIZADO

OBJECTIVE: To evaluate the physicochemical characteristics of lyophilized bovine grafts manufactured on a semi-industrial scale (Orthogen; Baumer S/A*) in accordance with a protocol previously developed by the authors. METHODS: The lyophilized bovine bone grafts were characterized by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffractometry (XRD), thermogravimetric (TG) analysis, differential exploratory scanning calorimetry (DSC) and Fourier-transform infrared (FT-IR) spectroscopy. RESULTS: Ca was the main component (60%) found in the samples, followed by P (28%) and O (5%). The mean (sd) pore size was 316 µm (146.7), ranging from 91.2 to 497.8 µm, and 333.5 µm (304.8), ranging from 87.2 to 963.9 µm, at 50x and 150x magnification, respectively. The hydroxyapatite peaks were at 26°C and 32°C, and mass losses were observed between 250°C and 640°C, corresponding to organic material and water. Two temperature transitions (45.67°C and 91.89°C) showed denaturation of type 1 collagen and dehydration of hydroxyapatite. CONCLUSION: The physicochemical assessment of lyophilized bovine bone grafts in accordance with the protocol developed at semi-industrial scale confirmed that this product presents excellent biocompatibility, with characteristics similar to natural bone.

Femoral and acetabular revision using impacted nondemineralized freeze-dried bone allografts

BackgroundFavorable results have been obtained by the use of deep-frozen bone allografts in total hip arthroplasty. However, owing to the shortage of deep-frozen allografts and the risk of infectious disease, other materials have been studied, such as sterile nondemineralized freeze-dried allografts. The aim of this study was to describe midterm clinical outcomes and radiographic bone incorporation of human freeze-dried bone grafts in 42 revision total hip arthroplasty procedures using cancellous impacted bone grafting.MethodsThis report presented clinical and radiographic evidence of allograft incorporation in 42 hip reconstructions performed between 1996 and 2002. The patient group included 13 (31%) men and 29 (69%) women with mean ± SD age of 63 ± 14 years (range 28–80 years). Meanfollow-upwas 82 months (range 63–127) months. Clinical analysis was based on the D’Aubigné-Postel score. Radiographic incorporation was defined according to specific criteria.ResultsThe D’Aubigné and Postel criteria showed adequate outcome in 38 (90%) of the patients. The radiographic evaluation revealed that allograft remodeling and incorporation were found in 39 (93.0%) and 36 (86.5%) of acetabular and femoral cases, respectively. The overall graft survival rate at an average follow-up of 8 years (range 5–10 years) was 90%.ConclusionsBone grafts obtained by the lyophilization process developed and carried out in our tissue bank provide suitable grafts for revision total hip arthroplasty. Clinical and radiographic midterm results were excellent, indicating that nondemineralized freeze-dried bone allografts are suitable for replacing deep-frozen grafts.

Physicochemical characterization of lyophilized bovine bone grafts

To evaluate the physicochemical characteristics of lyophilized bovine grafts manufactured on a semi-industrial scale (Orthogen; Baumer S/A*) in accordance with a protocol previously developed by the authors. Methods: The lyophilized bovine bone grafts were characterized by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffractometry (XRD), thermogravimetric (TG) analysis, differential exploratory scanning calorimetry (DSC) and Fourier-transform infrared (FT-IR) spectroscopy. Results: Ca was the main component (60%) found in the samples, followed by P (28%) and O (5%). The mean (sd) pore size was 316 μm (146.7), ranging from 91.2 to 497.8 μm, and 333.5 μm (304.8), ranging from 87.2 to 963.9 μm, at 50x and 150x magnification, respectively. The hydroxyapatite peaks were at 26°C and 32°C, and mass losses were observed between 250°C and 640°C, corresponding to organic material and water. Two temperature transitions (45.67°C and 91.89°C) showed denaturation of type 1 collagen and dehydration of hydroxyapatite. Conclusion: The physicochemical assessment of lyophilized bovine bone grafts in accordance with the protocol developed at semi-industrial scale confirmed that this product presents excellent biocompatibility, with characteristics similar to natural bone.

Caracterização físico-química de ossos liofilizados de origem bovina e humana

OBJECTIVES: To determine the physical and chemical characteristics and similarities between lyophilized bone from bovine and human sources manufactured in a semi-industrial scale, according to a modified protocol developed by the authors. METHODS: The percentages of fat extract (raw fat), total protein (total nitrogen) and mineral composition (total phosphorus, total P2O5, total calcium, total sodium, ashes and chlorides) was determined on the samples of lyophilized human and bovine bones. RESULTS: The percentage of fat extract and raw protein was of 0.14% and 0.06%; and 27.20% and 27.53%; whereas the mineral composition demonstrated 4.3% and 4.3% of nitrogen; 11.9% and 11.9% of total phosphorus; 27.1% and 27.2% of P2O5; 24.6% and 23.7% of total calcium (Ca/P relation: 2.06 and 1.99); 0.57% and 0.46% of total sodium; 64.8% and 64.3% of ashes; and 1.3% and 1.3% of chlorides, for samples of bovine and human bones, respectively. No statistical significant difference was observed between bovine and human bones after the lyophilization process. CONCLUSION: The assessment of physical and chemical characteristics of bovine and human lyophilized bones has clearly demonstrated that these bones kept virtually all characteristics of a raw bone and keep similarities to human counterparts, yielding an end product with good biocompatibility.

Artroplastia total do quadril de Spotorno

Uma coorte de 48 pacientes (54 quadris) submetidos a artroplastia total primaria de quadril nao-cimentada com protese de Spotorno®. O objetivo do estudo foi avaliar o desfecho clinico-radiologico da protese de Spotorno®,em um periodo de 20 anos (1985 a 2005), com seguimento medio de 17,5 anos (8-20anos). Na avaliacao clinica e funcional foram obtidos 92,7% de bons resultados. Encontrou-se osteopenia em 24 acetabulos (44,4%) e 30 femures (55,6%). O desgaste do polietileno esteve presente em 43 acetabulos (79,6%), com media de dois milimetros (0-5mm). A analise estatistica dos resultados sugeriu que a presenca de osteopenias nao esta relacionada ao desfecho clinico (p=0,75); o desgaste do polietileno, bem como a presenca de osteopenia, foi mais pronunciado nos pacientes abaixo de 55 anos (p<0,05). Concluimos que a utilizacao da protese de Spotorno® nessa coorte apresentou bons resultados, semelhantes aos relatos previos da literatura.

boVine lyoPhilized grafT (blg): hisTological analysis on behaVior in humans afTer 49 monThs

Objective: To analyze the histological behavior of bovine lyophilized grafts (BLG) produced according to a protocol developed by the first author, in humans over a 49-month period by measuring the graft/bone neoformation ratio in relation to the total mineralized area. Methods: This was a case series involving 12 patients: eight females (66%) and four males (34%), totaling 13 biopsies. BLG was used, and surgical reintervention was subsequently required during the period 2000 to 2011. The slides produced were stained with hematoxylin-eosin (HE), were analyzed by a pathologist and were digitized for the proposed evaluation. Results: The mean age was 57 years and the mean follow-up was 49 months (range: 6-115). The average proportion of BLG was 42% (range: 13-85) and neoformed bone, 58% (range: 15-87) in relation to the total area mineralized. Conclusions: This study demonstrated that the BLG used presented osteoconductive characteristics and biocompatibility. BLG is a therapeutic option that can be used in orthopedic surgery in which bone defects need to be filled.

Enxerto bovino liofilizado: comportamento histológico após seguimento de 49 meses em seres humanos

OBJECTIVE: To analyze the histological behavior of bovine lyophilized grafts (BLG) produced according to a protocol developed by the first author, in humans over a 49-month period by measuring the graft/bone neoformation ratio in relation to the total mineralized area. METHODS: This was a case series involving 12 patients: eight females (66%) and four males (34%), totaling 13 biopsies. BLG was used, and surgical reintervention was subsequently required during the period 2000 to 2011. The slides produced were stained with hematoxylin-eosin (HE), were analyzed by a pathologist and were digitized for the proposed evaluation. RESULTS: The mean age was 57 years and the mean follow-up was 49 months (range: 6-115). The average proportion of BLG was 42% range: 13-85) and neoformed bone, 58% (range: 15-87) in relation to the total area mineralized. CONCLUSIONS: This study demonstrated that the BLG used presented osteoconductive characteristics and biocompatibility. BLG is a therapeutic option that can be used in orthopedic surgery in which bone defects need to be filled.