A Novel Biodegradable Tubular Stent Prevents Pancreaticojejunal Anastomotic Stricture.

Stricture of pancreatic-enteric anastomoses is a major late complication of a pancreaticoduodenectomy for the treatment of a periampullary tumor and can lead to exocrine and endocrine insufficiency such as malnutrition and diabetes mellitus. We investigated the safety and efficacy of a biodegradable tubular stent (BTS) for preventing a pancreaticojejunostomy (PJ) anastomotic stricture in both a rat and porcine model. The BTS was manufactured using a terpolymer comprising poly p-dioxanone, trimethylene carbonate, and glycolide. A cohort of 42 rats was randomized into 7 groups of 6 animals each after BTS placement into the duodenum for the biodegradation assay. A total of 12 pigs were randomized equally into a control and BTS placement group. The effectiveness of the BTS was assessed by comparing radiologic images with histologic results. Surgical procedures and/or BTS placements were technically successful in all animals. The median mass losses of the removed BTS samples from the rat duodenum were 2.1, 6.8, 11.2, 19.4, 26.1, and 56.8% at 1, 2, 3, 4, 6, and 8 weeks, respectively. The BTS had completely degraded at 12 weeks in the rats. In the porcine PJ model, the mean luminal diameter and area of the pancreatic duct in the control group was significantly larger than in the BTS group (all p < 0.05). BTS placement thus appears to be safe and effective procedure for the prevention of PJ anastomotic stricture. These devices have the potential to be used as a temporary stent placement to treat pancreatic-enteric anastomoses, but further investigations are required for optimization in human.

Biological response to an experimental implant for tibial tuberosity advancement in dogs: A pre-clinical study.

In this study, we propose a novel bioresorbable bioactive implant for tibial tuberosity advancement (TTA). The implant consists of a gradually resorbing load-bearing shell which encompasses rapidly resorbing small casings loaded with silica-based bioactive glass (BG) particulates which promote bone formation and reduce the risk of infection. The shell and the casings are manufactured by 3D printing from two medical grade bioresorbable polymers (a polyglycolide/lactide based and a polydioxanone based) that have different degradation rates. The casings are expected to resorb within days after surgery to expose the BG particulates while the shell would retain the load-bearing properties of the implant for the time required by bone healing. Unlike the currently used metallic devices, the novel implant is resorbed and excreted from the body once its purpose is fulfilled. This study presents a logical progression from the in vitro characterisation of the materials and implants to the in vivo investigation of the experimental implants. This included mechanical testing of the materials, finite element analysis of a preliminary design of the novel TTA implant, assessment of the degradation behaviour of the polymers and the ion exchange of BG in simulated body fluid, and investigation of the biological response to the novel implants after implantation in rabbits. The osteointegration of the novel implants was comparable to the osteointegration of Ti6Al4V implants in the control group; the biological efficacy and safety were confirmed. The biological response was in line with the expectations. The proof of concept for the novel TTA implants was demonstrated.

Development of a Polymer-Based Biodegradable Neurovascular Stent Prototype: A Preliminary In Vitro and In Vivo Study.

Biodegradable stents are not established in neurovascular interventions. In this study, mechanical, radiological, and histological characteristics of a stent prototype developed for neurovascular use are presented. The elasticity and brittleness of PLA 96/4, PLDL 70/30, PCL, and PLGA 85/15 and 10/90 polymers in in vitro experiments are first analyzed. After excluding the inapt polymers, degradability and mechanical characteristics of 78 PLGA 85/15 and PLGA 10/90 stent prototypes are analyzed. After excluding PLGA 10/90 stents because of rapid loss of mass PLGA 85/15 stents in porcine in vivo experiments are analyzed. Angiographic occlusion rates 7 d, 1 month, 3 months, and 6 months after stent implantation are assessed. Histological outcome measures are the presence of signs of inflammation, endothelialization, and the homogeneity of degradation after six months. One case of stent occlusion occurs within the first 7 d. There is a prominent foreign-body reaction with considerable mononuclear and minor granulocytic inflammation combined with incomplete fragmental degradation of the struts. It is possible to produce a stent prototype with dimensions that fit the typical size of carotid arteries. Major improvements concerning thrombogenicity, degradation, and inflammatory response are required to produce biodegradable stents that are suitable for neurovascular interventions.

In Vivo Evaluation of Biodegradability and Biocompatibility of Fe30Mn Alloy.

OBJECTIVES: This study aims to evaluate the biodegradability and biocompatibility of an alloy of iron and manganese (Fe30Mn) in a bone model in vivo. METHODS: Resorption of a Fe30Mn wire was compared with traditional permanent 316L stainless steel (SS) wire after bilateral transcondylar femoral implantation in 12 rats. Evaluation of biodegradation over 6 months was performed using radiography, post-mortem histology and microscopic implant surface analysis. RESULTS: Corrosion and resorption of the novel iron-manganese implant with formation of an iron oxide corrosion layer was noted on all post-mortem histological sections and macroscopic specimens (corrosion fraction of 0.84 and 0 for Fe30Mn and 316L SS, respectively). Increased bone ongrowth was observed at the wire-bone interface (bone ongrowth fraction of 0.61 and 0.34 for Fe30Mn and 316L SS, respectively). Occasionally, poorly stained newly formed bone and necrotic bone in contact with corrosion was seen. In bone marrow, Fe30Mn alloy was scored as a mild local irritant compared with 316L SS (biocompatibility score of 8.8 and 5.3, respectively). There was no evidence of systemic adverse reaction. CLINICAL SIGNIFICANCE: Resorbable iron-manganese alloys may offer a promising alternative to permanent metallic implants. Further in vivo studies to control implant resorption at a rate suitable for fracture healing and to confirm the biocompatibility and biosafety of the resorbable Fe30Mn metallic implant are necessary prior to use in clinical settings.

Prospective Randomized Clinical and Radiographic Evaluation of a Novel Bioabsorbable Biocomposite Tibial Tuberosity Advancement Cage Implant.

OBJECTIVE: To evaluate the suitability of a novel bioabsorbable biocomposite cage (BC) implant for use in tibial tuberosity advancement (TTA) surgery in dogs with cranial cruciate ligament (CrCL) disease and to compare radiographic osteotomy healing scores and complications between groups that received either a BC or stainless steel cage (SSC). STUDY DESIGN: Prospective randomized clinical study. ANIMALS: Dogs with unilateral CrCL rupture (n=56). METHODS: TTA was performed in 60 consecutive dogs using either a BC (30 dogs) or SSC (30 dogs). Patient parameters, 6 week and 6 month postoperative radiographic osteotomy healing scores, time elapsed to postoperative rechecks, and complications were compared between groups. Osteotomy healing was graded using a 5-point (0-4) scale. Data were analyzed using Wilcoxon Rank Sum tests and χ(2) tests with significance set at P<.05. RESULTS: Fifty-six dogs (30 BC, 26 SSC) had complete medical and radiographic records at 6 months for inclusion in data analysis. Three complications occurred in the BC group (1 major, 2 minor) and 2 occurred in the SSC group (2 minor). There was no statistical difference in patient parameters, 6 week healing scores, or complications between BC and SSC groups. Healing scores at 6 months were significantly higher in the BC group (3.3 ± 0.52) compared to the SSC group (2.9 ± 0.69; P=.04). CONCLUSION: Based on improved BC osteotomy healing scores 6 months after surgery with no significant differences in complications compared to SSC, BC TTA cages are a viable alternative to SSC.

Ligation of the mesovarium in dogs with a self-locking implant of a resorbable polyglycolic based co-polymer: a study of feasibility and comparison to suture ligation.

BACKGROUND: Ligation of the mesovarium in female dogs may be cumbersome with risk of complications and is associated with intense noxious stimuli. A resorbable implant, a self-locking loop designed for surgery, was developed as an alternative to traditional ligation. The study aimed to test the feasibility of ligating the canine ovarian pedicle with the implant and to compare its performance to traditional suture ligation. RESULTS: In total 45 intact female dogs destined for elective ovariohysterectomy and adoption were included. In 21 dogs the new resorbable implant was used to ligate the mesovarium, and in 24 control dogs traditional suture was used with one encircling ligature. Mean weight of implant dogs was 10.7 ± 5.6 kg (range 3.5-22.0), and mean weight of control dogs was 12.8 ± 6.4 kg, (range 4.1-27.0). The body weight of dogs did not differ between groups (P = 0.25). In total, 42 ovarian pedicles were successfully ligated with the implant. In one control dog, intraoperative haemorrhage from the left ovarian pedicle was diagnosed. The mesovarium was re-ligated and haemostasis was confirmed. All dogs recovered uneventfully. The ligation time of the mesovarium was significantly shortened (P = 0.02) by using the self-locking implant versus a single ligature (3'28'' ± 1'05'' and 5'29'' ± 3'54'', respectively). Total duration of surgery differed between the groups (P = 0.02) with a shortened duration of surgery when using the self-locking implant (15'56'' ± 2'47'' and 20'39'' ± 8'58'', study group versus control group, respectively). In both groups, duration of surgery and time required to ligate the ovarian pedicle were longer in larger dogs than smaller dogs. CONCLUSION: The results of this feasibility study suggested the implant can be used to ligate the canine mesovarium. Compared with traditional suture ligation, the results suggested that time to ligate the ovarian pedicle and duration of surgery were significantly reduced with the implant. More time was required to perform surgeries in larger dogs.

Intra-articular implantation of gentamicin impregnated collagen sponge causes joint inflammation and impaired renal function in dogs.

OBJECTIVE: Gentamicin impregnated collagen sponge (GICS) can be used to treat intra-articular surgical site infections. High local concentrations of gentamicin can be reached for short periods; however the collagen vehicle may persist for much longer periods. We wished to determine the effect of sponge implantation on joint inflammation and renal function. METHODS: Eighteen medium sized mixed breed research dogs of hound type were randomized to two groups; arthroscopic implantation of GICS at gentamicin dose = 6 mg/kg (n = 9) or sham operation (n = 9). Endpoints consisted of joint inflammation measured by synovial fluid cell counts and cytokine concentrations; lameness measured by force plate asymmetry indices; and renal function measured by glomerular filtration rate (GFR) study. The prevalence of lesions associated with aminoglycoside nephrotoxicity was assessed by renal biopsy and transmission electron microscopy. RESULTS: Gentamicin impregnated collagen sponge implantation caused joint inflammation (p <0.01), lameness (p = 0.04), and decreased GFR (p = 0.04). No difference was observed in the prevalence of renal lesions on biopsy between the treatment and control groups (p = 0.49). CLINICAL SIGNIFICANCE: Gentamicin impregnated collagen sponge implantation causes joint inflammation and lameness as well as GFR reductions at the dose assessed. Gentamicin impregnated collagen sponge are not recommended for intra-articular implantation in dogs.

Modeling in vivo corrosion of AZ31 as temporary biodegradable implants. Experimental validation in rats.

In this paper, two complementary approaches, mathematical modeling and experimental results are combined to identify variables that affect the in vivo biodegradation of magnesium implants. The in vivo corrosion behavior of AZ31 alloy proposed for temporary applications as fixation of bone fractures has been modeled solving the Laplace equation by finite element method (FEM). Bar-shaped AZ31 implants of 1mm diameter and 20mm length were inserted in Wistar rat femurs with and without a fracture. The presence of gas around AZ31 implants inside the femurs has been detected in situ at the epiphysis and in fractured areas by computerized tomography (CT). Examining some in vivo conditions, the model confirms that magnesium-alloy devices have different biodegradation behavior, depending on the thickness of electrolyte at the implantation site and can be used for predicting the biodegradation behavior.

In vivo assessment of absorbable knotless barbed suture for single layer gastrotomy and enterotomy closure.

OBJECTIVE: To compare the performance of an absorbable barbed suture device to absorbable monofilament suture after single layer, appositional gastrotomy and enterotomy closure. STUDY DESIGN: Experimental comparative study. ANIMALS: Purpose-bred adult mongrel hounds (n = 14). METHODS: Bursting strengths up to 250 mmHg of incisional closure with either monofilament or barbed suture in a simple continuous, appositional pattern at sites in the stomach (2), jejunum (4), and colon (4) were compared at postoperative Days 3, 7, and 14. Time for incisional closure was compared between materials. RESULTS: Bursting strength was not significantly different between gastrotomies/enterotomies closed with the monofilament suture or the barbed device. Closure time was significantly reduced with the barbed device in jejunal enterotomy closure. CONCLUSION: The barbed device compared favorably with monofilament suture for gastrotomy and enterotomy (small intestine, colon) closure. Results demonstrate comparable burst strengths between monofilament suture and the barbed device. Closure time was significantly reduced in jejunum closure using the barbed device.

Evaluation of the efficacy and safety of single administration of 4.7-mg deslorelin acetate implants on egg production and plasma sex hormones in Japanese quail (Coturnix coturnix japonica).

OBJECTIVE: To evaluate the effects of 4.7-mg deslorelin acetate implants on egg production and plasma concentrations of 17ß-estradiol and androstenedione in Japanese quail (Coturnix coturnix japonica) over 180 days and assess safety of the implants in quail via gross and histologic examination. ANIMALS: 20 female Japanese quail. PROCEDURES: Following a 7-day period of consistent egg laying, quail were anesthetized and received a 4.7-mg deslorelin implant (treatment group; n = 10) or identical placebo implant (control group; 10) SC between the scapulae. Egg production was monitored daily. Plasma concentrations of 17ß-estradiol and androstenedione were measured on days 0 (immediately prior to implant injection), 14, 29, 62, 90, 120, 150, and 180 via radioimmunoassay. Birds were weighed periodically and euthanized at day 180 for complete necropsy. RESULTS: Egg production was significantly decreased in the treatment group, compared with the control group, from 2 to 12 weeks after implant injection. Egg production ceased in 6 of 10 quail in the treatment group (mean duration of cessation, 70 days). Plasma androstenedione and 17ß　-estradiol concentrations were significantly lower on day 29 in the treatment group than in the control group. On day 180, 17ß　-estradiol concentration was lower in control than in treated birds.No clinically relevant lesions were detected in either group at necropsy [corrected]. CONCLUSIONS AND CLINICAL RELEVANCE: 4.7-mg deslorelin acetate implants reversibly decreased egg laying for approximately 70 days in most of the Japanese quail evaluated. Further studies evaluating implants containing different concentrations of the drug are needed in quail and other avian species.

Healing and expression of growth factors (TGF-ß and PDGF) in canine radial ostectomy gap containing platelet-rich plasma.

OBJECTIVES: To evaluate bone healing in an experimental radial ostectomy in dogs treated with autologous platelet-rich plasma (PRP), through histological, densitometric, radiographic studies, as well as expression of growth factors in the ostectomy gap. METHODS: Twenty-one dogs were randomly divided into either a control or a PRP group. All underwent unilateral ostectomy of the radius to generate a gap of 2.0 mm, that was stabilized with external skeletal fixation. The ostectomy gap was either filled with PRP or left empty as a control. The radiographic and densitometric studies were performed after surgery, then at intervals until 60 days during the post-surgery period. Histological and immunohistochemical evaluations were performed at seven or 60 days post-surgery. Analyses were performed using a statistical analysis system, and the level of significance was set at p <0.05. RESULTS: The median radiographic healing score in the PRP group increased significantly between day 0 and day 60. Furthermore, at 60 days, the median healing score and the proportion of healed ostectomies in the control group (score 1; 1/6 healed) and the PRP group (score 5; 4/5 healed) were significantly different. There were differences between groups in radiographic and densitometric values at days 45 and 60. The histological evaluation showed advanced bone healing at 60 days in the PRP group and signs of delayed union in the control group. CLINICAL RELEVANCE: Platelet-rich plasma can be used as an adjuvant therapy because it may promote better bone healing of a radial ostectomy treated with external skeletal fixation in dogs.

Biodegradable sleeves for metal implants to prevent implant-associated infection: an experimental in vivo study in sheep.

OBJECTIVE: To evaluate biocompatibility of biodegradable sleeves containing antimicrobial agents, designed for local drug delivery to prevent implant-related infection. STUDY DESIGN: Synthetic polyester sleeves (a copolymer of glycolide, caprolactone, trimethylene carbonate, lactide) were cast as thin films. The antimicrobial agents incorporated in the sleeves included gentamicin sulfate, triclosan, or a combination of these drugs. ANIMALS: Adult sheep (n = 15). METHODS: Two limited contact dynamic compression plates (LC-DCP) with or without sleeves were implanted on tibiae (bilateral) of 15 sheep. Sleeves were placed over the plates before implantation. Beneath half of the plates, 5-mm drill hole defects were made in the near cortex. Samples were harvested 4 weeks later for histology and microradiography. RESULTS: Macroscopically, no irritation of bone or adjacent tissue was seen. Small remnants of sleeves were visible on histology, and positively correlated with the presence of macrophages and foreign body cells. Thick sections showed no difference between the test samples and controls in terms of fibrous capsule formation, periosteal remodeling, and defect remodeling. Inflammatory cells, macrophages, and foreign body cells were more prominent in sections with sleeves, but were not statistically significantly different from controls. Cell numbers were within normal physiologic limits normally seen as cellular response to foreign bodies consisting of polymers. CONCLUSION: The normal healing response indicated that the biodegradable sleeves demonstrate tissue biocompatibility.

Effects of the GnRH analogue deslorelin implants on reproduction in female domestic cats.

The aim of the present study was to investigate the safety and efficacy of deslorelin, a GnRH agonist, implants in suppressing estrus behavior and matings in a controlled ambient environment in feline queens in the presence of a tomcat. Local and utero-ovarian side effects of deslorelin implants were also investigated. The queens were housed in groups and assigned to one of three treatments: group 1 received 9.5 mg deslorelin implants (N = 14), group 2 received 5 mg megestrol acetate tablets and 9.5 mg deslorelin implants (N = 7), and group 3 were given placebo implants (N = 7). All implants were placed subcutaneously cranial to the interscapular region under xylazine hydrochloride sedation. Ovarian activity was monitored by fecal estradiol (E(2)) analyses. The animals were observed daily and checked individually at three-day intervals for behavioral signs of estrus. After 18.5 mo of trial, queens were ovariohysterectomized, and ovaries and uteri were weighed and evaluated histologically. E(2) levels were significantly lower in group 1 and 2 than in group 3 with an average of 128.48 ± 19.97 ng/g, 90.44 ± 7.16 ng/g and 283.26 ± 39.21 ng/g, respectively, excepting the first week of treatment. After inserting implants an initial estrus-like increase in fecal E(2) concentrations occurred in all treated queens except one female in group 2. Ovarian and uterine weights were significantly different among the groups (P < 0.01), and were lowest in groups 1 and 2. Primordial and primary follicle numbers were significantly higher in groups 1 and 2 than in group 3 (P < 0.001). Endometrial gland, antral follicle, and corpus luteum (CL) numbers were highest in group 3 (P < 0.01, 0.001, and 0.001, respectively) compared with groups 1 and 2. Deslorelin implants successfully suppressed estrus behavior and E(2) secretion in queens for 18.5 mo of the study period. Further investigations are needed to demonstrate the effects of GnRH agonists on ovarian interstitial tissue.

Arthroscopic reattachment of osteochondritis dissecans cartilage flaps of the femoropatellar joint: long-term results.

REASONS FOR PERFORMING STUDY: Long-term efficacy of arthroscopic cartilage reattachment for the treatment of osteochondritis dissecans (OCD) lesions in the equine femoropatellar joint is unknown. OBJECTIVE: To evaluate radiographic outcome and long-term performance of horses undergoing OCD reattachment. HYPOTHESIS: Separated OCD cartilage flaps may be reincorporated into the joint surface by reattachment rather than flap removal. METHODS: Polydioxanone pins were utilised arthroscopically to reattach OCD lesions in 40 of 44 joints from 27 horses. Cartilage was reattached when it had persisting perimeter continuity, the surface was not deeply fissured or irregular, and the cartilage was not protuberant or extensively mineralised. Bone marrow aspirate concentrate was grafted to additional areas denuded of cartilage or alongside reattached cartilage. RESULTS: Breeds included Thoroughbred (n = 18), Quarter Horse (n = 4), Warmblood (n = 3), Standardbred (n = 1) and Arabian (n = 1). Mean age was 9.7 months. Radiographic lesion length was 1.5-6.3 cm. Reattachment alone was used in 32 of 44 affected joints, a combination of debridement and reattachment in 8 joints and debridement alone in 4 joints. One horse was destroyed due to tendon laceration. Of the remaining 26 horses, mean duration of follow-up was 15.6 months (range 2 months-12 years). Radiographic resolution of OCD lesions treated with reattachment was significantly improved at 6 months. Twenty horses had long-term performance data, of which 19 were sound and had reached intended athletic potential. One horse remained lame, and an additional 6 were sound but remained unbroken or were convalescing. Thus, an overall success rate based upon continued soundness in performing horses was 95% (19/20). CONCLUSION: Cartilage flap reattachment can salvage OCD cartilage by integration with the underlying bone. POTENTIAL RELEVANCE: Extensive OCD cartilage flaps may be salvaged by reattachment which can result in normal radiographic subchondral bone contour and long-term athletic performance.

A novel subcutaneous controlled-release amoxicillin degradable implant for extended-interval administration in veterinary medicine.

Dosage forms of antimicrobials play a critical role in facilitating the attainment of pharmacokinetic-pharmacodynamic (PK-PD) targets as well as adherence in both veterinary and human medicine. The purpose of this study was to develop and evaluate a controlled-release subcutaneous amoxicillin implant for single-dose therapy of large ruminants such as goats, sheep, and deer. The degradable implant, designed to attain PK-PD targets following single administration, was evaluated for amoxicillin release rate and time-concentration profile. In vitro release studies demonstrated constant-rate release of approximately 40% of amoxicillin content within 96 h. In an in vivo study in goats, serving as a model for target animals, a serum concentration of approximately 0.4 mg/L was achieved within 8 h of implant insertion and maintained for >6 days. In comparison, in control goats given a standard single intramuscular amoxicillin dose of 15 mg/kg, amoxicillin peaked at 1.2 mg/L after 1 h, rapidly dropping to below detection level at 8 h. These results suggest that the proposed implant offers a unique modality for animal caregivers to conveniently administer a full antimicrobial course following a single dose of an efficient PK-PD-optimized dosage form. Furthermore, modifications of implant composition may allow for tailoring of its characteristics to various PK, PD, microbiological, and clinical requirements.

Novel gastroretentive controlled-release drug delivery system for amoxicillin therapy in veterinary medicine.

Beta-lactam antimicrobials, commonly used in both veterinary and human medicine, generally present short biologic half-lives, whereas their activity is enhanced as pathogen exposure is prolonged. These properties necessitate multiple-dose regimens of standard dosage forms, thereby hampering pet owner adherence, frequently resulting in therapeutic failure. This study presents a novel controlled-release gastroretentive oral drug delivery system for beta-lactams with which single-dose administration provides an effective antimicrobial course, optimizing pharmacokinetic (PK)-pharmacodynamic (PD) profiles, minimizing adverse effects and emergence of antimicrobial resistance and facilitating adherence. Our prototype sustained-delivery swelling-tablet (SDST), based on a degradable hydrophilic polymeric matrix, was designed to enable continuous input of these drugs to their absorption sites over several days. Several SDST formulations of the beta-lactam amoxicillin were evaluated in in vitro dissolution studies. Two formulations were selected for further in vivo canine studies, for determination of gastric retention and PK-PD profiling. Prolonged gastric retention times maintaining allowed for maintained effective drug concentrations against many clinically relevant pathogens for more than 48 h for one formulation and more than 5 days for the other. Both SDST formulations offer significant advantages over standard immediate-release therapy in achieving PK-PD goals and enhancing adherence. The prototypical formulations represent a novel platform which may be modified to meet various clinical requirements.

In vitro evaluation of free-form biodegradable bone plates for fixation of distal femoral physeal fractures in dogs.

OBJECTIVE: To design and manufacture free-form biodegradable polycaprolactone (PCL) bone plates and to compare mechanical properties of femoral constructs with a distal physeal fracture repaired by use of 5 stabilization methods. SAMPLE POPULATION: 40 canine femoral replicas created by use of additive manufacturing and rapid tooling. PROCEDURES: Surgery duration, mediolateral and craniocaudal bending stiffness, and torsional stiffness of femoral physeal fracture repair constructs made by use of 5 stabilization methods were assessed. The implants included 2 Kirschner wires inserted medially and 2 inserted laterally (4KW), a commercial stainless steel plate (CSP), a custom free-form titanium plate (CTP), thin (2-mm-thick) biodegradable PCL plates (TNP) placed medially and laterally, and thick (4-mm-thick) PCL plates (TKP) placed medially and laterally. RESULTS: Surgical placement of 4KW was more rapid than placement of other implants The mean caudal cantilever bending stiffness of CTP and CSP constructs was greater than that for TNP TKP and 4KW constructs, and the mean caudal cantilever bending stiffness of TNP and TKP constructs was greater than that for 4KW constructs. The mean lateral cantilever bending stiffness of TKP constructs was greater than that for 4KW constructs. Differences among construct types were not significant in yield strength, ultimate strength, yield torque, and ultimate torque. CONCLUSIONS AND CLINICAL RELEVANCE: The mechanical properties of fracture repair constructs made from free-form PCL biodegradable plates compared favorably with those of constructs made from Kirschner wires. The impact of PCL plates on musculoskeletal soft tissues, bone healing, and bone growth should be evaluated before clinical use.

Use of a biodegradable self-expanding stent in the management of a benign oesophageal stricture in a cat.

An 11-year-old domestic shorthair cat presented with a six-week history of regurgitation following a dental procedure. Endoscopy identified a single oesophageal stricture in the cervical oesophagus. Stricture reformation occurred following endoscopic balloon catheter dilation on two occasions. Following a third balloon dilation a biodegradable polydioxanone self-expanding stent was placed across the stricture site. Following the implantation the cat was able to eat soft canned food orally without regurgitation. Fluoroscopic examination performed four months after placement indicated that the stent was no longer present and the cervical oesophagus was able to pass boluses of canned food with no signs of obstruction.

Biomateriais para reparação cirúrgica da parede abdominal em animais domésticos: revisão / Biomaterials for surgical repair of abdominal wall in animals: review / Biomateriales para reparación quirúrgica de la pared abdominal en animales domésticos: revisión

A reparação dos tecidos que compõem a parede abdominal é uma necessidade cirúrgica constante. Especificamente para utilização em animais domésticos, o maior desafio é o desenvolvimento de biomateriais que suportem forças exercidas pelas vísceras, em virtude de sua posição quadrupedal e pela movimentação das estruturas após o procedimento cirúrgico. Nas últimas décadas diversos materiais sintéticos têm surgido e apresentado resultados significativos em relação à tensão a que são submetidos e à formação de tecido cicatricial. No entanto, o conhecimento interdisciplinar das estruturas moleculares responsáveis pela antigenicidade, proliferação celular e dos mecanismos que possam alterá-los, proporcionou a obtenção de biomembranas derivadas de tecidos orgânicos, com resultados superiores em relação à interação com os tecidos dos hospedeiros dos implantes e à regeneração tecidual. Assim, o objetivo desta revisão é de conflitar os principais trabalhos de uso comparativo de biomateriais naturais e sintéticos na parede abdominal e compilar os conhecimentos moleculares, que norteiam o desenvolvimento de técnicas de obtenção de biomateriais naturais.

The repairing of abdominal wall tissues is a constant surgical necessity. Specifically for use in domestic animals, the biggest challenge is the development of biomaterials that support forces exerted for the viscera, due to quadruped position and for the movement of the structures after the surgical procedure. In the last decades several synthetic materials have appeared and presented significant results in relation to the tension that are submitted and to the cicatricial tissue formation. However, the interdisciplinary knowledge of antigenic molecular structures, cellular proliferation signs and of the mechanisms that can modify them provided the attainment of biomembranes derived from organic tissues with superior results in relation to the interaction with host tissues and to tissue regeneration. Therefore, the objective of this review is to conflict the main works of comparative use of natural and synthetic biomaterials in the abdominal wall and to compile the molecular knowledge that guide the development of techniques of attainment of natural biomaterials.

La reparación de los tejidos que componen la pared abdominal es una necesidad quirúrgica constante. Específicamente para utilización en animales domésticos, el mayor reto es el desarrollo de biomateriales que soporten fuerzas ejercidas por las vísceras, debido a su posición cuadrupedal y por el movimiento de las estructuras tras el procedimiento quirúrgico. En las últimas décadas, muchos materiales sintéticos han surgido y han mostrado resultados significativos en relación a la tensión a que son sometidos y a la formación de tejido cicatrizal. Sin embargo, el conocimiento interdisciplinario de las estructuras moleculares responsables por la antigenicidad, la proliferación celular y de los mecanismos que pueden alterarlos, resultó a obtener biomembranas derivadas de tejidos orgánicos, con resultados superiores en relación a la interacción con los tejidos huéspedes de los implantes y a la regeneración de los tejidos. Por lo tanto, el objetivo de esta revisión es discutir los principales trabajos de uso comparativo de biomateriales naturales y sintéticos en la pared abdominal y compilar los conocimientos moleculares, que guían el desarrollo de técnicas de obtención de biomateriales naturales.

Effects of autologous platelet rich plasma gel and calcium phosphate biomaterials on bone healing in an ulnar ostectomy model in dogs.

The aim of the study was to evaluate the bone healing properties of an osteopromotive platelet rich plasma (PRP) gel in combination with osteoconductive calcium phosphate (CaP) ceramic granules in a long-bone critical size defect in dogs. A standardised 2 cm long ulnar ostectomy was performed bilaterally in four dogs to compare new-bone formation by CaP matrix with and without association with PRP. Radiographic and histological evaluations were performed blindly. Radiographic evaluation was performed at three, six, nine, 12 and 16 weeks postoperatively. Quantitative measurements of new-bone formation were compared using statistical analysis. At explantation 16 weeks after surgery, no significant ossification was present, neither with CaP granules alone nor in association with PRP gel, and there was no difference of radiodensity between the groups. Qualitative histological evaluation demonstrated for both types of implants the presence of non-mineralised fibrous connective tissue around the CaP granules. New-bone formation was only present to a very small extent within the macropores of the CaP granules at the distal bone-implant interface. In our model which exhibited very limited osteoconduction, neither the CaP granules alone nor in association with PRP were sufficient to stimulate bone healing. In this canine model employing a critical size ulnar gap, the combination of CaP granules and PRP did not effectively promote bone regeneration.