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Internal craniofacial distraction with biodegradable devices: early stabilization and protected bone regeneration.

Internal craniofacial distraction has several advantages over distraction with external devices. The scars may be less conspicuous; the devices are buried and therefore easier for patients to tolerate; and the devices are more rigidly secured to bone, preventing uncontrolled rotation of the advancing segments. There are several types of internal devices. The Modular Internal Distraction System developed by one of the authors (S.R.C.) and Stryker-Leibinger, Inc. has had widespread use for midface distraction, but requires a substantial surgical procedure for device removal. This is justified in selected children with syndromic craniosynostosis, who frequently need secondary orbitocranial reconstruction at the conclusion of distraction with any type of device. It would be preferable to develop a device that would retain the positive characteristics of the Modular Internal Distraction system, while allowing easy removability. Moreover, the entire distraction procedure would benefit from a technique that would assist in bone regeneration within the distraction gap. Such a biodegradable, stabilizing device may enable early explanation, accelerating the recovery period, while providing fixation of the distraction gap and protected bone regeneration. Accordingly, we have developed a new, biodegradable distraction device with Macropore, Inc. that may be used with the Modular Internal Distraction system to permit easy removability of the device without the need for a large operation for exposure. Second, we have developed a biodegradable stabilizer that permits earlier removal of the distraction device while providing simultaneous fixation and protected bone regeneration. Last, we have demonstrated the feasibility of midcourse correction of the distraction procedure, should this be necessary for whatever reason.

Absorbable Implants↗

Polymer-based biodegradable drug delivery systems in pain management.

Pain is an unpleasant sensory experience commonly produced by damage to bodily tissues and it is one of the most significant public health problems, because 21.5% of the world population is estimated to suffer from pain. It results in a total loss of more than 165 billion US dollars each year in the United States alone. Pain reflects a mixture of various pathophysiologic, psychologic, and genetic contributions. When undertreated, pain usually results in serious immune and metabolic upset. Therefore, it requires wide understanding and intensive effort for a better management. Currently, pain control is limited by the modest efficiency of the used drugs, the serious side effects of these drugs, and the inefficacy of conventional drug administration. By the introduction of the technology of biodegradable controlled-release devices into clinical practice, pain control not only benefits from these novel methods for a better delivery of various drugs, but the side effects of the drugs are reduced because use of the devices improves patient compliance. Biodegradable controlled-release devices are polymer-based devices that are designed to deliver drugs locally in a predesigned manner. Recently, there was a high interest in developing these devices for the delivery of different drugs used for pain control. This paper first highlights the dimensions and basics of the problem of pain. Then, it presents an overview of the biodegradable polymers that are used in drug delivery systems and summarizes the studies carried out on these systems in the field of pain management. We refer to our experience in developing a device for multimodal drug delivery, including the use of nanotechnology. Future perspectives are also presented.

Absorbable Implants↗

Delayed local treatment of rabbit tibial fractures with biodegradable cefazolin microspheres.

The prevention of infection is a primary objective in the treatment of open fractures. The objective of this study was to compare the efficacy of biodegradable, poly (DL-lactide-co-glycolide) cefazolin microspheres and free cefazolin powder in Staphylococcus aureus contaminated rabbit tibial fractures when treatment was delayed for 2 hours. Fractures were produced in the tibia of rabbits, inoculated with Staphylococcus aureus, and 2 hours later treated by either direct local application of cefazolin microspheres or an equivalent dose of free cefazolin powder. Control animals did not receive antibiotic therapy. The fractures then were stabilized with a bone plate, and the animals were observed for 8 weeks. Local antibiotic therapy with biodegradable cefazolin microspheres prevented the establishment of infection in all animals, and cultures of the tibiae were sterile in all cases. In contrast, clinical evidence of infection developed in 50% of the rabbits that had been treated with free cefazolin powder and 71% of the control animals. Staphylococcus aureus was recovered from the tibiae of 75% and 100% of these animals, respectively. The results of this study suggest that local antibiotic therapy with biodegradable, controlled release cefazolin microspheres may be useful for the management of open fractures in humans, even when treatment is delayed for several hours after bacterial contamination.

Animals↗

Biodegradable interlocking nails for fracture fixation.

Serious problems such as stress shielding, allergic reactions, and corrosion are associated with the use of metallic fracture fixation devices in fractured long bones. Metal implants often are removed during a second retrieval operation after fracture healing has completed. A biocompatible implant that degrades slowly during implantation would obviate the need for a second operation and save the patient from considerable physical, psychologic, and financial discomfort. The biodegradable implant must provide the fractured limb sufficient support for a certain time, allowing early loading. A gradual transfer of load from the biodegradable implant to the bone would result in a better product of bone healing and avoid stress shielding. In an animal model using adult sheep, two types of biodegradable polymer interlocking nails were tested in comparison with a stainless steel interlocking nail. Fracture healing, mechanical properties of the bones, degradation behavior in vivo and in vitro, and tissue response were monitored during a 2 1/2-year followup study. To detect shifts in acid base relations caused by the release of acid compounds, pH measurements were performed. Fracture healing was unimpaired, and the mechanical test results of all three groups were excellent. Histologic analysis showed a mild inflammatory response, but no pH shifts were observed. The results of this study justify additional research on these promising materials.

Absorbable Implants↗

Biodegradable external tracheal stents and their use in a rabbit tracheal reconstruction model.

OBJECTIVES/HYPOTHESIS: To design and develop an external biodegradable tracheal stent for use in airway reconstructive surgery. STUDY DESIGN: Experimental model. METHODS: Biodegradable external tracheal stents were fabricated from polyglycolic acid and poly(D,L-lactide-co-glycolide) (85:15). In vitro studies were performed to analyze the mechanical properties and degradative characteristics of these stents. Then the stents were tested in vivo in an anterior tracheal reconstruction model in New Zealand white rabbits. RESULTS: The average dry modulus for the external stents was 1,800 kilopascal (kPa). All of the external stents cracked by 4 weeks in buffer solution. Significant mass loss was not appreciated until after 10 weeks in solution, but by 20 weeks the stents were nearly 100% degraded. In the in vivo portion of the study, the attrition rate for the control group was 23.1% versus 50% for the external stent group. The stridor rate was approximately 38% for both groups Of the rabbits that survived the entire 3 months of the study, the stented group, when measured by a balloon catheter method, had more patent airways than the control group, with an average stenosis of 27.8% versus 47.2%, respectively (P < .05). However, more accurate postmortem cast measurements of the internal airways did not confirm this. CONCLUSIONS: The external biodegradable tracheal stent employed in this study degraded in a predictable fashion and may provide a new method to augment surgical reconstruction of the anterior tracheal wall.

Absorbable Implants↗

Quantitative histologic study of the influence of anterior spinal instrumentation and biodegradable polymer on lumbar interbody fusion after corpectomy. A canine model.

Histomorphometric and microradiographic studies were performed to investigate whether there are different rates of bone remodeling based on the intrinsic stability with anterior spinal instrumentation and to evaluate if biodegradable polymer could be used clinically as the material of choice for anterior spinal instrumentation. Twenty-one coon hounds underwent anterior and posterior spinal destabilizing procedures to produce a reproducible amount of spinal instability: corpectomy of L5, discectomies and partial facetectomies of L4-5 and L5-6, resections of L5 lamina, spinous process, supra- and interspinous ligament, and ligamentum flavum. Group 1 (N = 7) underwent anterior autogenous ulna strut graft alone at L4-6; group 2 (N = 7) underwent anterior biodegradable polymer strut alone at the same level; group 3 (N = 7) underwent same bone graft as in group 1, augmented by anterior Kaneda device. Six months after surgery quantitative histologic study showed that device-related osteopenia occurred in spines treated with Kaneda device. Within the L5 vertebral body the volumetric density of bone (mm3/cm3) was less for the group with Kaneda device (group 3) compared with that without instrumentation (group 1, P less than 0.05). In the spine treated with biodegradable polymer, no adverse host tissue responses were observed histologically. In addition, osteoconductive abilities of the polymer were suggested microscopically. Its mechanical property, however, was not rigid enough to stabilize the corpectomized spine.

Animals↗

The use of an injectable, biodegradable calcium phosphate bone substitute for the prophylactic augmentation of osteoporotic vertebrae and the management of vertebral compression fractures.

STUDY DESIGN: A biomechanical study comparing two materials for augmentation of osteoporotic vertebral bodies and vertebral bodies after compression fracture. OBJECTIVES: To compare an injected, biodegradable calcium phosphate bone substitute with injected polymethylmethacrylate bone cement for strengthening osteoporotic vertebral bodies and improving the integrity of vertebral compression fractures. SUMMARY OF BACKGROUND DATA: Injection of polymethylmethacrylate bone cement into fractured vertebral bodies has been used clinically. However, there is concern about thermal damage to the neural elements during polymerization of the polymethylmethacrylate bone cement as well as its negative effects on bone remodeling. Biodegradable calcium phosphate bone substitutes have been studied for enhancement of fixation in fractured vertebrae. METHODS: Forty fresh osteoporotic thoracolumbar vertebrae were used for two separate parts of this study: 1) injection into osteoporotic vertebrae: intact control (n = 8), calcium phosphate (n = 8), and polymethylmethacrylate bone cement (n = 8) groups. Each specimen then was loaded in anterior compression until failure; 2) injection into postfractured vertebrae: calcium phosphate (n = 8) and polymethylmethacrylate bone cement (n = 8) groups. Before and after injection, the specimens were radiographed in the lateral projection to determine changes in vertebral body height and then loaded to failure in anterior bending. RESULTS: For intact osteoporotic vertebrae, the average fracture strength was 527 +/- 43 N (stiffness, 84 +/- 11 N/mm), 1063 +/- 127 N (stiffness, 157 +/- 21 N/mm) for the group injected with calcium phosphate, and 1036 +/- 100 N (stiffness, 156 +/- 8 N/mm) for the group injected with polymethylmethacrylate bone cement. The fracture strength and stiffness in the calcium phosphate bone substitute group and those in the polymethylmethacrylate bone cement group were similar and significantly stronger than those in intact control group (P < 0.05). For the compression fracture study, anterior vertebral height was increased 58.5 +/- 4.6% in the group injected with calcium phosphate and 58.0 +/- 6.5% in the group injected with polymethylmethacrylate bone cement as compared with preinjection fracture heights. No significant difference between the two groups was found in anterior vertebral height, fracture strength, or stiffness. CONCLUSION: This study demonstrated that the injection of a biodegradable calcium phosphate bone substitute to strengthen osteoporotic vertebral bodies or improve vertebral compression fractures might provide an alternative to the use of polymethylmethacrylate bone cement.

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Regenerative signals for intestinal epithelial organoid units transplanted on biodegradable polymer scaffolds for tissue engineering of small intestine.

BACKGROUND: Our laboratory is investigating the tissue engineering of small intestine using intestinal epithelial organoid units seeded onto highly porous biodegradable polymer tubes. This study investigated methods of stimulation for optimizing neointestinal regeneration. METHODS: Intestinal epithelial organoid units harvested from neonatal Lewis rats were seeded onto porous biodegradable polymer tubes and implanted into the omentum of adult Lewis rats in the following groups: (1) the control group (group C), implantation alone (n=9); (2) the small bowel resection (SBr) group, after 75% SBr (n=9); (3) the portacaval shunt (PCS) group, after PCS (n=8); and (4) the partial hepatectomy (PH) group, after 75% PH (n=8). Neointestinal cyst size was recorded using ultrasonography. Constructs were harvested at 10 weeks and were examined using histology. Morphometric analysis of the neomucosa was obtained using a computer image analysis program (NIH Image, version 1.59). RESULTS: Cyst development was noted in all animals. Cyst lengths and diameters were significantly larger in the SBr group at 7 and 10 weeks compared with the other three groups (P<0.05; analysis of variance [ANOVA], Fisher's protected least significant difference). Histology revealed a well-vascularized tissue with a neomucosa lining the lumen with invaginations resembling crypt-villus structures. Morphometric analysis demonstrated a significantly greater villus number, height, area, and mucosal surface in the SBr group compared with the other three groups and a significantly greater crypt number and area in the PCS group compared with group C (P<0.05; ANOVA, Fisher's protected least significant difference). CONCLUSIONS: Intestinal epithelial organoid units transplanted on porous biodegradable polymer tubes can successfully vascularize, survive, and regenerate into complex tissue resembling small intestine. SBr and, to a lesser extent, PCS provide significant regenerative stimuli for the morphogenesis and differentiation of tissue-engineered small intestine.

Animals↗

Biodegradable materials in arthroscopy.

The use of biodegradable materials as implants has revolutionized the way medicine is practiced today. This review provides a general description of salient biodegradable polymeric materials currently used in arthroscopy. These materials include polyglycolic acid, self-reinforced polyglycolic acid, poly-L-lactic acid, self-reinforced polylactic-L-acid, poly-D-L-lactic acid, copolymer of poly-D-L-lactic acid polyglycolic acid, and polyglyconate. The mechanical strength, degradation properties, and widespread use of these materials, especially in the knee and shoulder, are discussed individually. Also discussed are the relatively few complications that are related to these materials' arthroscopic use. Future directions in biodegradable materials, including smart polymers, are also considered. In the future, novel techniques to identify the ideal polymer for a particular application will need to be developed to minimize the risk for implant complications.

Absorbable Implants↗

Biodegradable composite implants.

Biodegradable implants are established in the field of operative sports medicine. So-called composite implants are increasingly used. The idea to improve biocompatibility and osteoconductivity of biodegradable polymers by modifying them with a ceramic component, has led to the development of these composite implants. Today, an increasing variety of composite implants are available. They have substantially different material characteristics, which depend on matrix polymer choice and the additional ceramic. The material characteristics influence the mechanical properties, in vivo degradation, the osseous replacement and the host-tissue response. It is important to understand their biologic base for a better knowledge of the advantages and risks associated with using composite implants in the field of operative sports medicine. The purpose of this review is to focus on current developments in biodegradable composite implants and their biologic base.

Absorbable Implants↗

The efficacy of a hydroxyapatite composite as a biodegradable antibiotic delivery system.

Local biodegradable carriers have been studied for use as a skeletal drug delivery system. This study investigated the efficacy of a local biodegradable composite composed of hydroxyapatite, plaster of Paris, and chitosan impregnated with antibiotics to treat methicillin-resistant Staphylococcus aureus. The composite, impregnated with vancomycin, fosfomycin, or sodium fusidate was tested for its sustained elution characteristics during 3 months and compared with similarly impregnated polymethylmethacrylate using the modified disc diffusion technique. Physicochemical properties using scanning electron microscopy and xray diffraction analysis of each preparation also were analyzed. Vancomycin and fosfomycin incorporated into the hydroxyapatite composite inhibited the organism for 3 months, whereas sodium fusidate was effective only for 3 weeks. Vancomycin and fosfomycin loaded into the hydroxyapatite composite had a significantly better inhibitive effect than when loaded in polymethylmethacrylate, whereas sodium fusidate loaded in polymethylmethacrylate showed a significantly better inhibitive effect than when loaded in the hydroxyapatite composite. Scanning electron microscopy and xray diffraction analysis elucidated the patterns of each drug release profile. The local hydroxyapatite composite is a promising local biodegradable delivery system for vancomycin and fosfomycin, whereas PMMA is a better carrier for sodium fusidate in treating methicillin-resistant staphylococcus aureus osteomyelitis.

Anti-Bacterial Agents↗

Biodegradable implants for Pipkin fractures.

The current study was designed to clarify whether biodegradable poly-L/DL lactide pins provide an operative alternative for fixation of Pipkin fractures. Nine patients with Pipkin fractures (one with Pipkin Type I, one with Pipkin Type II, and seven with Pipkin Type IV fractures) were treated surgically between 1996 and 2002. In all patients, the femoral head fractures were fixed with biodegradable, 2.7-mm and 2.0-mm polylactide pins. Eight patients were followed up for an average of 54.2 months. One patient died before the final followup. Eight fractures healed uneventfully. In one patient, a persisting femoral head defect led to posttraumatic arthritis requiring insertion of a femoral endoprosthesis at 1 year. The average range of motion of the affected hips of all patients at followup was 109 degrees -0 degrees -0 degrees in flexion and extension. External and internal rotation averaged 37 degrees -0 degrees -29 degrees . One patient had Brooker Grade I heterotopic ossification develop, and another had a Grade II heterotopic develop. Merle d'Aubigne and Postel ratings showed two excellent and five satisfactory results (average score, 13.1). Adverse effects from the polylactide implants were not observed. Pipkin fractures can be fixed successfully with biodegradable polylactide pins.

Absorbable Implants↗

Vertebral reconstruction with biodegradable calcium phosphate cement in the treatment of osteoporotic vertebral compression fracture using instrumentation.

OBJECTIVE: To assess the efficacy of posterior instrumentation and vertebral reconstruction with biodegradable calcium phosphate cement (CPC) in the treatment of osteoporotic vertebral compression fracture with neurologic deficit. BACKGROUND: Vertebroplasty consists of the injection of polymethylmethacrylate (PMMA) cement into the vertebral body. While PMMA has high mechanical strength, it cures fast and thus allows only a short handling time. Other potential problems of using PMMA injection may include damage to surrounding tissues due to the high polymerization temperature or by the toxic unreacted monomer and the lack of long-term biocompatibility. Bone mineral cements such as calcium carbonate and CPCs have a longer working time and low thermal effect. They are also biodegradable while providing good mechanical strength. However, the viscosity of injectable mineral cements is high, and the infiltration of these cements into the vertebral body has been questioned. Recently, the infiltration properties of CPC have been significantly improved, making it more suitable for injection into the vertebral bodies for vertebral reconstruction. METHODS: Five patients were included in this open prospective study. Inclusion criteria were delayed collapsed vertebral compression fractures responsible for severe pain and neurologic dysfunction necessitating posterior decompression surgery. Of five patients, two were male and three were female with an average age at surgery of 80.4 years (71-85 years) and an average duration of follow-up of 2.5 years (2-3.5 years). Evaluation of clinical data was based on x-ray, Japanese Orthopaedic Association (JOA) score for low back pain (full score is 29 points), and Visual Analog Scale (VAS). RESULTS: The levels of the delayed collapsed vertebrae were T10, L1, and L2 (for one patient each) and L4 (two patients). All patients were in poor condition, for example, renal failure, heart failure, and chronic hepatitis. The average operative time was 2 hours (1 hour 36 minutes to 2 hours 16 minutes), and intraoperative bleeding was 181 mL (85-236 mL). As for clinical symptoms, preoperative JOA score averaged 17.8 points and was improved to 26 points postoperatively, while the preoperative VAS score of 8.6 points improved to 2 points postoperatively. Morphologic evaluation showed preoperative vertebral compression ratio averaged 41% and improved to 74% immediately after the operation and finally settled at 68%. Just one of five cases experienced late vertebral collapse 3 months after the operation. CONCLUSION: Vertebral reconstruction with biodegradable CPC in the treatment of osteoporotic vertebral compression fracture using instrumentation was a safe and useful surgical treatment.

Aged↗

Serial intravascular ultrasonographic measurements after implantation of biodegradable polymer-coated stents in porcine coronary arteries.

BACKGROUND: Biodegradable stent coatings provide a potential for local drug delivery at the time of vascular injury, while possible tissue toxicity is avoided through constant degradation, leaving behind a bare metal stent. DESIGN: Serial three-dimensional (3D) intravascular ultrasonographic results on bare Megaflex stents and biodegradable polymer-coated Megaflex stents (Hyper stents) (Eurocor, Bonn, Germany) were compared 1 and 4 weeks after intracoronary implantation in pigs. METHODS: Under general anaesthesia, the left anterior descending and circumflex coronary arteries of domestic pigs were stented with Megaflex and Hyper stents, using right femoral artery access. Control coronary angiography and intravascular ultrasonography (IVUS) were performed 1 and 4 weeks after stent implantation using left femoral artery access and right carotid artery access. After recording of angiographic and IVUS data, the pigs were allowed to recover. RESULTS: The 1- and 4-week IVUS follow-ups revealed less neointima formation with Hyper stents than with Megaflex stents: 1-week intimal volume, 11.8+/-0.93 compared with 15.02+/-4.18 mm3, P=0.065; intimal area, 0.81+/-0.06 compared with 1.1+/-0.16 mm2, P =0.003; maximal intimal thickness, 0.12+/-0.01 compared with 0.14+/-0.02 mm, P =0.049; 4-week intimal volume, 12.4+/-1.77 compared with 27.32+/-12.79 mm3, P =0.016; intimal area, 0.82+/-0.12 compared with 1.95+/-0.65 mm2, P=0.003; and maximal intimal thickness, 0.13+/-0.04 compared with 0.30+/-0.10 mm, P=0.003. CONCLUSIONS: Implantation of biodegradable polymer-coated (Hyper) stents results in significantly less neointima formation 1 and 4 weeks after intracoronary implantation than with bare Megaflex stents. Taking advantage of the good collateralization of femoral and carotid arteries of pigs, the use of different arterial accesses allows serial angiographic and 3D IVUS measurements on neointimal development without sacrificing the animals.

Animals↗

Segmental uterine horn replacement in the rat using a biodegradable microporous synthetic tube.

To investigate the possible use of a biodegradable microporous synthetic tube for fallopian tube replacement, polyetherurethane/poly-L-lactide (PU/PLLA) grafts in the uterine horn of the rat were studied and their patency and healing characteristics compared with those of nonbiodegradable polytetrafluoroethylene (PTFE; Teflon) grafts as well as with those of reanastomosed uterine horns. Regarding the healing characteristics, the PU/PLLA grafts were superior to the PTFE graft, as was indicated by the regeneration of endometrium and the extensive perigraft tissue ingrowth. However, the graft/uterine anastomoses of the PU/PLLA and PTFE grafts became obstructed by a plug of mucosal folds, all reanastomosed, uterine horns in the control experiments remaining open. In conclusion, although biodegradable microporous PU/PLLA uterine horn grafts have better healing characteristics than PTFE grafts, they easily obstruct at the graft/uterine junction. Mucosal suturing and/or the use of splints may contribute to the feasibility of biodegradable microporous artificial fallopian tubes in tubal surgery.

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Electrically conductive biodegradable polymer composite for nerve regeneration: electricity-stimulated neurite outgrowth and axon regeneration.

Normal and electrically stimulated PC12 cell cultures and the implantation of nerve guidance channels were performed to evaluate newly developed electrically conductive biodegradable polymer composites. Polypyrrole (PPy) doped by butane sulfonic acid showed a significantly higher number of viable cells compared with PPy doped by polystyrenesulfonate after a 6-day culture. The PC12 cells were left to proliferate for 6 days, and the PPy-coated membranes, showing less initial cell adherence, recorded the same proliferation rate as did the noncoated membranes. Direct current electricity at various intensities was applied to the PC12 cell-cultured conductive membranes. After 7 days, the greatest number of neurites appeared on the membranes with a current intensity approximating 1.7-8.4 microA/cm. Nerve guidance channels made of conductive biodegradable composite were implanted into rats to replace 8 mm of sciatic nerve. The implants were harvested after 2 months and analyzed with immunohistochemistry and transmission electron microscopy. The regenerated nerve tissue displayed myelinated axons and Schwann cells that were similar to those in the native nerve. Electrical stimulation applied through the electrically conductive biodegradable polymers therefore enhanced neurite outgrowth in a current-dependent fashion. The conductive polymers also supported sciatic nerve regeneration in rats.

Absorbable Implants↗

Repair of radial fractures in toy breed dogs with self-reinforced biodegradable bone plates, metal screws, and light-weight external coaptation.

OBJECTIVE: To describe a surgical technique for, and outcome after, treatment of radial fractures with biodegradable self-reinforced polylactide plates and metal screws, and external coaptation. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Eleven Toy breed dogs. METHODS: Radial fractures were repaired by application of a single or 2 stacked biodegradable self-reinforced polylactide plates (poly-L/D, L-lactide, stereocopolymer [LL-and DL-lactide ratio 70/30]; SR-PLA (70/30) implants) secured with metal screws, and light-weight external coaptation. Healing was evaluated clinically and by radiography at 2, 4, 6, 8, 9, 12, 24-26 weeks, and at 1 and 2 years. Owners were interviewed 3 years after surgery. RESULTS: Radial fracture lines disappeared within 4-14 weeks in 10 dogs; an implant failed in 1 dog. Ambulation was excellent for healed fractures. Excessive skin tension led to removal of implants in 1 dog and suture repair in another dog. No foreign body reaction from implant degradation was observed and the plate was usually no longer palpable at 2 years. One dog had a fracture through a screw hole at 1 year. CONCLUSION: Healing and complication rates after repair of radial fractures with SR-PLA (70/30) plates were considered similar or better than reported after repair with metallic plates or external fixation in Toy breed dogs. No radiographic signs of osteopenia were identified under the plate during follow-up. CLINICAL RELEVANCE: Biodegradable polylactide plates could be considered as an alternative to metal plates for radial fracture repair in Toy breed dogs, however available plates are likely not strong enough when used as a single plate. Implant removal is usually not needed.

Absorbable Implants↗

Coronally positioned flap procedures with or without a biodegradable membrane in the treatment of human gingival recession. A 6-year follow-up study.

BACKGROUND: Short-term data have indicated that treatment of gingival recession type defects by coronally positioned flap procedures with or without biodegradable membranes may result in similar treatment outcome. The aim of this study was to compare 12-month and 6-year follow-up results for these two treatment approaches. METHODS: Twenty patients with buccal bilateral Miller Class I or Class II gingival recession defects in cuspids or bicuspids were treated randomly by coronally positioned flap alone (20 sites) or in combination with a biodegradable membrane (20 sites). Clinical measurements at baseline, 6, 12 months and 6 years included apical extent of gingival recession, width of the defect at the cemento-enamel junction (CEJ), width of keratinized tissue, as well as attachment level and probing depth. Eleven patients were available for the 6-year evaluation. RESULTS: At 12 months (20 sites), both treatments resulted in significant gain of root coverage (p<0.001), stable probing depth, and increased attachment level (p<0.001). The 6-year evaluation (11 sites) showed a significant gain of root coverage for the non-membrane group only (p<0.05). No significant between-group differences were detected for any other treatment variable regardless of smoking status (p>0.05). Compared with baseline, the 6-year results showed that seven membrane sites gained root coverage, three were unchanged and one lost root coverage. For the 11 non-membrane sites, eight gained root coverage, and three were unchanged. The five membrane and the 10 non-membrane sites exhibiting complete root coverage at 6 months were reduced to two and one, respectively, at the 6-year evaluation. CONCLUSIONS: The coronally positioned flap procedure offers a simple and reliable treatment alternative as a root coverage procedure in Class I and Class II recession type defects. Placement of a biodegradable membrane underneath the flap does not seem to improve neither the short- nor the long-term results. Long-term outcome stability seems to be critically dependent on a continuous follow-up program with re-instruction in non-traumatic brushing habits.

Absorbable Implants↗