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PubMedDate not supplied

Bioabsorbable screws for reduction of Lisfranc's diastasis in athletes.

This was a study of 15 athletes who sustained Lisfranc's diastasis and were treated with surgical reduction and fixation with 3.5mm bioabsorbable poly-L lactic acid screws. Patients were prospectively evaluated for their ability to return to activity, maintenance of reduction, and need for implant removal. The average patient age was 28 years; there were 9 females and 6 males. Average followup was 36 months (range: 12-62). The mean return to activity time was 4.2 months (range: 3-6), with a significant difference between males and females (P=.02), 3.4 versus 4.7 months, respectively. The mean preoperative American Orthopedic Foot and Ankle Society midfoot score was 35.4+/-25.0, which increased postoperatively to 92.7+/-7.7 (P=.00001). Overall there were 10 "excellent," 4 "good," and 1 "poor" result. Patients were statistically more likely to have less than an excellent result when diagnosis was delayed by more than 6 weeks (P=0.01). One patient demonstrated a radiographic loss of reduction but returned to full sports activities. The patient with the longest delay in diagnosis demonstrated anatomic reduction but exhibited radiographic degenerative changes and scored a poor result. Three patients required a second surgery for screw or screw head removal. Bioabsorbable screws appear sufficient for treating Lisfranc's diastasis but do not necessarily obviate fixation removal.

Absorbable Implants↗

PubMed2004

[Study on relationship of biodegradable properties of PGLA film in vivo and in vitro].

This experimental study on the biodegradable properties of poly(glycolide-co-lactide)[PGLA] film in vivo and in vitro was aimed to investigate the relationship between in vivo degradation process and in vitro degradation process. First, PGLA film was cut to 1 cm x 1 cm in size. It was put into artificial saliva and PBS solution respectively in vitro, and was implanted into subcutaneous tissue in Wistar rat in vivo. Then the mass loss rate was calculated every week not only for sample in vitro but also in vivo. The molecular weight was measured every two weeks. The results showed that the degradable speed of PGLA was faster in artificial saliva than in PBS solution. The change of molecular weight was earlier than that of mass loss rate. The degradable period in vitro was about 9-10 weeks. The degradable period in vivo was about 8 weeks. The rate of in vivo degradation was 1.33 times faster than that of in vitro. In conclusion, the degradation of PGLA in vitro was mainly a chemical degradation process achieved by hydrolysis of ester bond. The degradation of PGLA in vivo would be affected by stress and by biological factors, thus the degradation process was apparently faster in vivo, but both accorded with the degradation kinetics model of aliphatic polyester. There was some relationship of biodegradation between in vitro and in vivo.

Absorbable Implants↗

PubMed2001

Effects of ceramic component on cephalexin release from bioactive bone cement consisting of Bis-GMA/TEGDMA resin and bioactive glass ceramics.

The purpose of this study was to elucidate the effect of amount of ceramic cement powder on drug release from bioactive bone cement. The associated bone-bonding strength was also investigated. The bioactive bone cement under investigation consisted of bisphenol-alpha-glycidyl methacrylate (Bis-GMA), triethylene-glycol dimethacrylate (TEGDMA) resin and a combination of apatite- and wollastonite-containing glass-ceramic (A-W GC) powder. A-W GC powder (50%, 70% and 80% w/w) containing 5% cephalexin (CEX) powder hardened within 5 min after mixing with Bis-GMA/TEGDMA resin. The compressive strength of the cement with or without drug increased with increasing the amount of ceramic powder. The compressive strength of the 80% ceramic cement without the incorporation of cephalexin was 194 MPa. This compressive strength was about 3 times higher than that for polymethylmethacrylate cement. After the cement was implanted in the proximal metaphysis of the tibiae of male rabbits, the failure load for the cement was found to increase with increasing of the amount of ceramic powder. This finding suggested that the cement formed a bonding with bone. In vitro CEX release from bioactive bone cement pellets in a simulated body fluid at pH 7.25 and 37 degrees C continued for more than 2 weeks. Drug release profile followed the Higuchi equation initially, but not at later stages. The drug release rate increased with increasing amount of ceramic powder in the mixture. Since the pore volume of the cement increased with increasing of amount of ceramic powder, the drug diffused in the pores between the ceramics particle and polymer matrix. As hydroxyapatite precipitated on the cement surface, the drug release rate decreased, as observed at the later release stage. These results suggest that varying the amount of ceramic powder in the cement system could control the drug release rate from bioactive bone cement.

Absorbable Implants↗

PubMed2004

Le Fort I miniplate osteosynthesis: a randomized, prospective study comparing resorbable PLLA/PGA with titanium.

The aim of this study was to compare the use of resorbable osteosynthesis material (LactoSorb) with titanium osteosynthesis for the fixation of Le Fort I osteotomies with respect to long-term stability and morbidity. To achieve exact cephalometric measures, five tantalum micro implants were inserted in the maxilla during surgery. A total of 60 patients undergoing a non-segmented Le Fort I osteotomy were randomized to one of the treatments and were followed for 1 year postoperatively. For the osteotomies fixated with LactoSorb, the lateral cephalometric analysis demonstrated a statistically significant difference in the vertical position of the maxilla after 6 weeks as the position became more superior compared with the postoperative situation (mean change of 0.6 mm). In the titanium group no significant changes in position were observed. There were no statistically significant changes in the position of the maxilla from 6 weeks to 12 months in either of the treatment groups. The changes in maxillary postion were not clinically noticeable in either of the treatment groups, and all treatments were completed with satisfactory results. There were two cases of infection and wound dehiscence in the LactoSorb group, whereas titanium osteosynthesis was more often palpable after 6-12 months and required surgical removal in three cases.

Absorbable Implants↗

PubMedDate not supplied

Serial magnetic resonance imaging evaluation of a bioabsorbable interference screw and the adjacent bone.

The purpose of this prospective study was to review, using expanded clinical assessment tools, the initial use of a bioabsorbable interference screw (copolymer 85/15 D, L lactide/glycolide) in anterior cruciate ligament (ACL) reconstruction at the Wels Hospital, Austria. The study enlisted 32 patients of whom 28 were available for follow-up at minimum of 2.5 years. Since the implant material was new and the screw would not show on plain film radiographs, the clinical assessment was expanded beyond the usual historical and physical findings. The evaluation included opportunistic knee joint aspiration and repeat magnetic resonance imaging (MRI) studies to investigate the longevity of the implant and potential adverse effects of this new bioabsorbable material. The knee joint aspirations showed no infection. Serial MRIs showed the physical presence of the screw to remain intact for 4 months and disappear in 6 months. The MRIs showed minimal collection of edema around the bone tunnels that resolved by 12 months. There were no symptoms or adverse clinical result correlated with the MRI evidence of edema. There was temporary bone tunnel expansion. The clinical results were good. The OAK-score (Orthopädische Arbeitsgruppe Knie) showed 89.5% excellent and good results, 7% fair results and 3.5% poor results. The average score was 90.7 points (range, 63 to 100 points). The knee joint stability measured with the KT-1000 arthrometer showed 93% to have a 3-mm or less difference compared with the unoperated knee. This bioabsorbable interference screw appeared safe and effective for fixation of bone blocks during ACL reconstruction while producing no occult infection or adverse clinical response during the degradation process.

Absorbable Implants↗

PubMed2003

Dose escalation of carmustine in surgically implanted polymers in patients with recurrent malignant glioma: a New Approaches to Brain Tumor Therapy CNS Consortium trial.

PURPOSE: This New Approaches to Brain Tumor Therapy CNS Consortium study sought to determine the maximum-tolerated dose (MTD) of carmustine (BCNU) that can be implanted in biodegradable polymers following resection of recurrent high-grade gliomas and the systemic BCNU exposure with increasing doses of interstitial BCNU. PATIENTS AND METHODS: Forty-four adults underwent tumor debulking and polymer placement. Six patients per dose level were studied using polymers with 6.5%, 10%, 14.5%, 20%, and 28% BCNU by weight. Toxicities were assessed 1 month after implantation by a safety monitoring committee to determine whether subsequent escalations should occur. Nine additional patients were studied at the MTD to confirm safety. BCNU blood levels were obtained before and after polymer implantation. RESULTS: No dose-limiting toxicities were identified at the 6.5%, 10%, or 14.5% dose levels, although difficulties with wound healing, seizures, and brain edema were noted. At the 20% dose, these effects seemed more prominent, and six additional patients were treated at this dose and tolerated treatment well. Three of four patients receiving the 28% polymers developed severe brain edema and seizures, and accrual to this cohort was stopped. Nine additional patients received 20% polymer, confirming this as the MTD. Maximum BCNU plasma concentrations with the 20% loaded polymers were 27 ng/mL. Overall median survival was 251 days. CONCLUSION: The MTD of BCNU delivered in polymer to the surgical cavity is 20%. This polymer provides five times more BCNU than standard commercially available BCNU polymers and results in minimal systemic BCNU exposure. Additional studies are needed to establish the efficacy of high-dose BCNU polymers.

Absorbable Implants↗

PubMed2004

Successful treatment of scaphoid fractures and nonunions using bioabsorbable screws: report of six cases.

PURPOSE: A variety of implants have been used for the fixation of scaphoid fractures, but we have found no reports on bioabsorbable screws used for this purpose. We report 6 cases of scaphoid fractures treated with bioabsorbable screws. METHODS: Six patients with scaphoid waist region fractures (3) and nonunions (3) treated using bioabsorbable self-reinforced poly-L-lactide screws. Interposition of a bone graft from the iliac crest was used in 4 cases. Immobilization in a short arm-thumb spica cast was applied after surgery for an average of 8 weeks. RESULTS: Solid union was achieved in 5 cases. Using the Mayo modified Green-O'Brien wrist score, we graded the results as excellent in 1 case, good in 4 cases, and poor in the single case of nonunion. CONCLUSIONS: These results suggest that bioabsorbable self-reinforced poly-L-lactide screws might offer an alternative in the fixation of scaphoid fractures and nonunions in the future, provided that cannulated screws of appropriate size will be available.

Absorbable Implants↗

PubMed2000

Histological evaluation of different biodegradable and non-biodegradable membranes implanted subcutaneously in rats.

Different types of biodegradable membranes have become available for guided tissue regeneration. The purpose of this study was to evaluate histologically three different biodegradable membranes (Bio-Gide, Resolut and Vicryl) and one non-biodegradable membrane (expanded polytetrafluoroethylene/e-PTFE) implanted subcutaneously in rats. Five subcutaneous pouches were created in each of 24 rats. One of the four test membranes was randomly placed in each of the four pouches and one pouch was left empty to serve as a control. Histological evaluation was performed after 4, 10 and 21 days which demonstrated that e-PTFE was well tolerated and encapsulated by a fibrous connective tissue capsule. There was capsule formation around Resolut and Vicryl and around Bio-Gide in the early phase there was a wide inflammatory zone already. e-PTFE and Vicryl were stable materials while Resolut and Bio-Gide fragmented in the early phase. In the late phase Vicryl was surrounded by an increasing amount of multinucleated macrophages and a thin capsule, whilst around Resolut and Bio-Gide a strong foreign body reaction was observed. Also granuloma formation was noted around the fragmented Resolut material in its capsule and a mild inflammatory reaction surrounding Bio-Gide within its thin capsule.

Absorbable Implants↗

PubMed2006

Functional growth in tissue-engineered living, vascular grafts: follow-up at 100 weeks in a large animal model.

BACKGROUND: Living autologous vascular grafts with the capacity for regeneration and growth may overcome the limitations of contemporary artificial prostheses. Particularly in congenital cardiovascular surgery, there is an unmet medical need for growing replacement materials. Here we investigate growth capacity of tissue-engineered living pulmonary arteries in a growing lamb model. METHODS AND RESULTS: Vascular grafts fabricated from biodegradable scaffolds (ID 18+/-l mm) were sequentially seeded with vascular cells. The seeded constructs were grown in vitro for 21 days using biomimetic conditions. Thereafter, these tissue-engineered vascular grafts (TEVGs) were surgically implanted as main pulmonary artery replacements in 14 lambs using cardiopulmonary bypass and followed up for < or = 100 weeks. The animals more than doubled their body weight during the 2-year period. The TEVG showed good functional performance demonstrated by regular echocardiography at 20, 50, 80, and 100 weeks and computed tomography-angiography. In particular, there was no evidence of thrombus, calcification, stenosis, suture dehiscence, or aneurysm. There was a significant increase in diameter by 30% and length by 45%. Histology showed tissue formation reminiscent of native artery. Biochemical analysis revealed cellularity and proteoglycans and increased collagen contents in all of the groups, analogous to those of native vessels. The mechanical profiles of the TEVG showed stronger but less elastic tissue properties than native pulmonary arteries. CONCLUSIONS: This study provides evidence of growth in living, functional pulmonary arteries engineered from vascular cells in a full growth animal model.

Absorbable Implants↗

PubMed1999

Improved osteoconduction of cortical bone grafts by biodegradable foam coating.

Alteration of the geometrical surface configuration of cortical bone allografts may improve incorporation into host bone. A porous biodegradable coating that would maintain immediate structural recovery and subsequently allow normal graft healing and remodeling by promoting bony ingrowth could provide an osteoconductive surface scaffold. We investigated the feasibility of augmenting cortical bone grafts with osteoconductive biodegradable polymeric scaffold coatings. Three types of bone grafts were prepared: Type I--cortical bone without coating (control), Type II--cortical bone coated with PLGA-foam, Type III--cortical bone coated with PPF-foam. The grafts were implanted into the rat tibial metaphysis (16 animals for each type of bone graft). Post-operatively the animals were sacrificed at 2 weeks and 4 weeks (8 animals for each type of bone graft at each time point). Histologic and histomorphometric analysis of grafts showed that the amount of new bone forming around the foam-coated grafts was significantly higher than in the control group (uncoated; p < 0.02). Although both foam formulations were initially equally osteoconductive, PLGA-based foam coatings appeared to have degraded at two weeks postoperatively, whereas PPF-based foam coatings were still present at 4 weeks postoperatively. While significant resorption was present in control allografts with little accompanying reactive new bone formation, PLGA-coated bone grafts showed evidence of bone resorption and subsequent bony ingrowth earlier than those coated with PPF-based foams suggesting that PPF-coated cortical bone grafts were longer protected against host reactions resulting in bone resorption.

Absorbable Implants↗

PubMed2006

[Structure and performance of calcium polyphosphate for bone tissue engineering].

Porous calcium polyphosphate (CPP) has shown promise of tissue engineered implant application because of the biocompatibility and biodegradation. CPP with different polymerization degree were prepared by controlling the calcining time, and its polymerization degree could be calculated by developed method in this paper. Different crystal types CPP were prepared by quenching from the melt and crystallization of amorphous CPP. From the in vitro degradation, carried out in Tris-HCl buffer, the degradation velocity of CPP was controllable. The weight loss of CPP with different polymerization degrees and crystal types were different. With the increasing of polymerization degree, the weight loss during the degradation was decreasing, contrarily the strength of CPP was increasing. The amorphous CPP could degrade completely in 17 days while gamma-CPP do completely in 25 days. The degradation velocity beta-CPP and alpha-CPP was slower than gamma-CPP and the weight loss was about 12% and 5% respectively. The results of this study indicate that CPP have potential applications for bone tissue engineering as inorganic polymeric biomaterials.

Absorbable Implants↗

PubMed2001

[Mechanical comparison of biodegradable intervertebral lumbar cages].

INTRODUCTION: A biodegradable interbody cage for lumbar spine fusion would be able to solve several problems associated with the use of metallic cages. In a biomechanical in vitro study using human lumbar spines three different biodegradable poly(L-lactide-co-D,L-lacitide)(PLDLLA) cages were compared to metallic cages of the same design. MATERIAL AND METHOD: 40 human cadaver lumbar specimens (L3-S1) were tested in flexion, extension, rotation, and bending with a non-destructive flexibility method using a nonconstrained testing apparatus. Seven different groups were examined: (1) control group (intact) (n = 40); (2) unstable group (after discectomy L4/5) (n = 40), (3) autologous iliac crest bone graft (n = 8), (4) BAK-Cage (n = 8), (5) BIO-Cage 1 (PLDLLA) (n = 8), (6) BIO-Cage 2 (PLD-LLA/hydroxylapatite-buffer) (n = 8) and (7) BIO-Cage 3 (PLDLLA/hydroxylapatite particles of different size) (n = 8). Additionally, destructive compression tests of all implants were performed. RESULTS: In comparison to the intact motion segment all cages showed significantly lower range of motion (ROM) in all test modes (P < 0.01). There was no significant difference in stiffness values and ROM between BIO-Cages and metallic cages. Axial compression stiffness and failure load were significantly highest for metallic BAK-cages (P < 0.05). No significant difference for failure load was observed between BIO-cage 1 and the intact motion segment. However, in comparison to the intact motion segment failure load was significantly lower for BIO-cage 2 and 3 (P < 0.05). CONCLUSION: The results of this study are encouraging, because the biodegradable cages were able to limit lumbar spine motion similar to the metallic cages. Especially, the biodegradable PLDLLA cage consisting of pure polymer (BIO-Cage 1) showed adequate initial compression strength. However, further in vivo animal experiments are essential prior to the clinical application of biodegradable lumbar interbody fusion cages.

Absorbable Implants↗

PubMed2002

Neovascularization and vascular markers in a foreign body reaction to subcutaneously implanted degradable biomaterial in mice.

To study the spatiotemporal processes of angiogenesis during a foreign body reaction (FBR), biodegradable bovine collagen type-1 (COL-I) discs were implanted in mice for a period up to 28 days. The cellular infiltration (consisting mainly of macrophages, giant cells and fibroblasts), and the extent of neovascularization into the discs were determined. Also the expression levels and/or distribution of the endothelial cell markers von Willebrand factor (vWF), platelet endothelial cell adhesion molecule-1 (PECAM-1)/CD31, MECA-32 antigens and endomucin, and of the basal lamina marker collagen type IV (Coll IV) were analysed. In time, a strong neovascularization of the discs was observed, with frequently occurring vascular sprouting, and intussusceptive growth of vessels. In this model, vWF, MECA-32 and endomucin antibodies often failed to stain neovessels in the COL-I discs. In contrast, staining for collagen IV basal lamina component in combination with CD31 covered the complete range of neo-vessels. We conclude that the model described in this study is a useful model to study FBR induced angiogenesis because of the active neovascularization taking place during prolonged periods of time.

Absorbable Implants↗

PubMed2003

In vivo bone engineering in a rabbit femur.

The repair of bone defects in reconstructive surgery has significant limitations. Donor site morbidity, limited supply of autograft, and risks and complications associated with allografting and synthetic bone substitutes are among the most significant. In an effort to address these problems, the search for an ideal bone replacement has led to the development of a new method of poly(lactide-co-glycolide) (PLGA) foam processing, enabling the production of a biodegradable scaffold with similar porosity to human trabecular bone. In this study, these scaffolds were evaluated for bone repair in vivo in a femoral critical-sized segmental defect in New Zealand White (NZW) rabbits. Three groups of nine animals were investigated. In the first group, the critical-sized defects were empty. Scaffolds alone were implanted in the second group, whereas autologous bone marrow cell-loaded scaffolds were implanted in the third group. Animals ambulated freely for 8 weeks after surgery, and bone formation throughout the defects was serially assessed radiographically and quantified using a bone formation index (BFI) measure. Postmortem radiography and histology were also undertaken to examine bone formation. There was a significant effect of applying this technology to the amount of bone formed in the defects as determined by the BFI (F = 3.41, P < 0.05). The mean BFI for the cell-loaded scaffolds was greater than for the control group at all measured time points (2-, 4-, 6-, and 8-week radiographs). This difference was significant for the 2- and 8-week radiographs (P < 0.05). Qualitative histological assessment confirmed these findings. We concluded from these findings that these PLGA scaffolds loaded with marrow-derived progenitor cells yield significant bone formation in a critical-sized rabbit femoral defect. This technology comprising a novel scaffold design and autologous cells may provide an alternative to current strategies for reconstruction of bony defects.

Absorbable Implants↗

PubMed1999

Matrix metalloproteinases and tissue inhibitors of metalloproteinases in joint fluid of the patients with loose artificial hip joints.

The pseudojoint cavity formed in patients undergoing total hip arthroplasty (THA) is later remodeled to synovial membrane-like tissue, which produces pseudosynovial fluid. This pseudosynovium also is an important source of matrix metalloproteinases (MMPs). As it is widely speculated that synovial fluid MMPs may contribute to local tissue degradation in rheumatoid arthritis (RA) and osteoarthritis (OA), we hypothesize that locally produced MMPs are found in the pseudosynovial fluid, via which they have access to the implant-host interface, and that if they retain their proteolytic potential, they might contribute to aseptic loosening. Enzyme-linked immunosorbent assay (ELISA), immunoblotting, and zymography were used to analyze MMPs and tissue inhibitors of metalloproteinases (TIMPs) in synovial fluid in aseptic loosening, which was compared to RA and OA. Pseudosynovial THA fluid was characterized using low levels of MMP-1 but moderate levels of MMP-13 and MT1-MMP (MMP-14). Due to the lack of an appropriate assay, MMP-13 and MT1-MMP were not similarly assessed, but the immunoblotting indicated that they were in the 56 kD intermediate proteolytically processed forms. The MMP-9 level was intermediate between RA and OA. MMP-2 was on a significant level, but there were no differences among study groups. The THA group also was characterized using relatively high levels of TIMP-1 and TIMP-2. Accordingly, MMP-9 and MMP-2 were found to occur in the 92 kD and 72 kD proenzyme form, respectively, with full activity retained in all study groups. The data suggest that proMMP-2-TIMP-2 and proMMP-9-TIMP-1 complexes are formed in the pseudosynovial fluid due to the excess of TIMPs over MMPs in aseptic loosening of THA. TIMP-complexed MMPs are resistant to MMP-mediated proteolytic activation, which may explain their latency and proenzyme zymogen form. Thus, formation of stabilizing proMMP-TIMP complexes enable transportation of proMMPs far from their original site of production. Due to motion-associated cyclic changes of the intra-articular pressure, fluid-phase MMPs stabilized by TIMPs might be absorbed to implant surfaces and interface tissues and help to dissect the implant/cement-to-bone interface in situ. Consequently, they may contribute to local proteolytic/tissue destructive events and aseptic loosening.

Aged↗

PubMed2003

Pharmacokinetic and toxicity study of an intraocular cyclosporine DDS in the anterior segment of rabbit eyes.

PURPOSE: To establish the safety and pharmacokinetic efficacy of an Oculex Drug Delivery System (DDS; Oculex Pharmaceuticals, Inc., Sunnyvale, CA) containing cyclosporin A (CsA) in the anterior segment of the rabbit eye. METHODS: The Oculex DDS is an intraocular, sustained-release, drug delivery system comprising a biodegradable lactic acid-glycolic acid copolymer. A controlled prospective study was performed that involved implanting a DDS containing 0.5 mg of CsA into the anterior chamber (AC) of the right eyes of 16 New Zealand White rabbits. A placebo DDS was implanted into the left eyes of these same rabbits as the control. Slit lamp examinations and AC taps were performed serially, and the rabbits were killed and the globes removed at 2, 4, 8, and 12 weeks for histology and determination of CsA drug levels. Analysis of CsA levels was performed with high-performance liquid chromatography-mass spectrometry. RESULTS: High concentrations of CsA were detectable in all layers of the cornea (epithelium, corneal stroma and endothelium) throughout the 3-month period. Low CsA levels were detected in the aqueous, whereas no CsA was detectable in the blood. There were no adverse reactions observed. CONCLUSIONS: The Oculex DDS CsA device is effective in delivering long-term levels of CsA to corneal tissues, without adverse effects. Further studies in an animal model of corneal transplant rejection should be performed to determine the potential of this device in the prophylaxis and treatment of corneal transplant rejection in humans.

Absorbable Implants↗

PubMed2005

HA/TCP compounding of a porous CaP biomaterial improves bone formation and scaffold degradation--a long-term histological study.

In the present study, two biphasic calcium phosphate biomaterials (BCP) with HA/TCP ratios of 50/50 and 30/70 were obtained from a pure HA biomaterial. The biomaterials which showed the same three-dimensional geometry were implanted into corticocancellous costal defects of sheep. In the specimens of all three biomaterials, abundant bone formation, mineral dissolution from the biomaterial scaffolds, and active cellular resorption of the scaffolds was present after 6 and 12 months. Backscattered electron microscopy showed bone invasion into the pores of the scaffolds and micromechanical interlocking at the bone/biomaterial interface without intervening soft tissue. The pattern of bone formation and scaffold resorption was different for cortical and cancellous bone. No time-based effect, however, was observed. Overall, the BCP biomaterials had formed significantly more bone than the HA biomaterial. Also, scaffold resorption, which was followed by a replacement with newly formed bone, was significantly higher in the BCP biomaterials. Although no significant differences were observed between both BCP biomaterials, the present study had confirmed the assumption that HA/TCP compounding was suitable to improve bone formation and scaffold resorption in the investigated biomaterials and at the same time maintain the osteoconductive properties of the scaffolds.

Absorbable Implants↗

PubMed2001

Reinnervation of a denervated skeletal muscle by spinal axons regenerating through a collagen channel directly implanted into the rat spinal cord.

In the present study, the continuity between the central nervous system (CNS) and the peripheral nervous system (PNS) was restored by mean of a collagen channel in order to reinnervate a skeletal muscle. Three groups of animals were considered. In the first group, one end of the collagen channel was implanted in the cervical spinal cord of adult rats. The other end was connected to a 30-mm autologous peripheral nerve graft (PNG) implanted into the denervated biceps brachii muscle. The gap between the spinal cord and the proximal nerve stump varied from 3 to 7 mm. In the second group of animals, the distal end of the PNG graft was ligatured in order to compare the survival of the growing axons in the presence and in the absence of a muscular target. In the third group of animals, the extraspinal stump of the collagen channel was ligatured. Our study demonstrates that spinal neurons and dorsal root ganglion (DRG) neurons can grow long axons through the collagen channel over a 7-mm gap and reinnervate a denervated skeletal muscle. The results also indicate that the presence of a PNG at the extraspinal stump of the collagen channel is essential for axonal regrowth and that the muscle target contributes to the long-term maintenance of the regenerating axons. These data might be interesting for clinical application when the continuity between the CNS and PNS is interrupted such as in root avulsion.

Absorbable Implants↗