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PubMed2006

A prospective, randomized, clinical and radiographic study after arthroscopic Bankart reconstruction using 2 different types of absorbable tacks.

PURPOSE: The aim of the study was to compare the clinical and radiographic results after arthroscopic Bankart reconstruction using 2 different types of absorbable implant. TYPE OF STUDY: Randomized controlled trial. METHODS: A randomized series of 40 patients who had recurrent, unidirectional, post-traumatic shoulder instability were included in the study. All patients underwent an arthroscopic Bankart reconstruction involving either polygluconate co-polymer (PGACP group, n = 20) or self-reinforced poly-L-lactic acid polymer (PLLA group, n = 20) tack implants. The patients underwent clinical and radiographic assessments preoperatively and at 2 years. Additional radiographic assessments were performed at 6 months. RESULTS: Preoperatively, the study groups were comparable in terms of demographics as well as clinical parameters. One patient in each group had a redislocation (5%) during the follow-up period of 2 years. No subluxations were registered. No statistically significant differences were found between the study groups in terms of strength in abduction, range of motion, and Rowe or Constant scores. There was a significant increase in degenerative changes during the follow-up period in both study groups (P = .004). However, no significant differences in degenerative changes were registered between the study groups either preoperatively or at the 2-year follow-up. There were no significant differences in the radiographic visibility of the drill holes used for the absorbable implants between the study groups at the 6-month assessment. However, at the 2-year assessment, the radiographic visibility of the drill holes was significantly greater (P = .004) in the patients in the PLLA group than those in the PGACP group. At the 2-year assessment, no correlation was found between the appearance of the drill holes and the degenerative findings (PGACP group, rho = 0.44; PLLA group, rho = 0.42). CONCLUSIONS: Two years after arthroscopic Bankart reconstruction using either PGA polymer or PLA polymer implants, the overall clinical results were comparable. Radiographic assessments revealed that the degenerative changes increased in both study groups during the follow-up period. Furthermore, the visibility of the drill holes on the 2-year radiographs was greater after using PLLA implants than after using PGACP implants. LEVEL OF EVIDENCE: Level I.

Absorbable Implants↗
PubMed1996

Strength of the fixation of patellar tendon bone grafts using a totally absorbable self-reinforced poly-L-lactide expansion plug and screw. An experimental study in a bovine cadaver.

In a bovine cadaver study, bone-tendon-bone graft fixation strength with different graft geometry and fixation devices was measured to evaluate the fixation strength of totally absorbable implants: a 6.0-mm expansion plug and 6.3-mm screw both made of self-reinforced polylactide (SR-PLLA). Comparison was made with 6.5-mm AO cancellous screw. Maximum tensile force to dislodge the bone plug from the bone tunnel was recorded. First, two preliminary tests were performed. In the first test, triangular bone plugs were used (9-mm diameter). The direction of the pull force was parallel to the bone tunnel. The maximum tensile forces were 786 N in femoral insertions and 625 N in tibial insertions, mean. After this, we evaluated the influence of change in the pullout direction. In the second test, a circular bone plug was used with no fixation but the direction of the pull force was parallel to the tibial or femoral axis and the bone plug (10-mm diameter) was in a 30 degrees to 40 degrees angle to the direction of the pull force and it was compressed to the tunnel (9-mm diameter). The maximum tensile forces were 783 N in femoral insertions and 695 N in tibial insertions, mean. In the final third test, we used a curved saw in harvesting the graft. This made a half-circular bone block with a diameter of 12 mm. The maximum tensile force to dislodge the bone plug from the bone tunnel was recorded and the pull force was in a 30 degrees to 40 degrees angle to the tunnel. The results were evaluated with Student's t-test and Mann-Whitney U-test. With the AO screw, the maximum tensile force to dislodge the bone plug from the bone tunnel was 2,113 +/- 407 N (mean +/- standard deviation) and it was better than the fixation strength of the SR-PLLA expansion plug, 1,379 +/- 328 N (P = .009, t-test) and better than the fixation strength of SR-PLLA screw, 1,454 +/- 230 N (P = .007, t-test). However, the maximum tensile force of both SR-PLLA implants in all measurements in the third test were above 1,100 N and it seems that the initial strength of totally absorbable implants is enough for the clinical use.

Animals↗
PubMed1976

Gelatin implants in retina surgery.

Gelatin absorbable implants are a practical and effective material for scleral buckling. They may be used in segmental scleral buckling, meridional implants, aphakic detachments, lower temporal dialyses and macular holes. We describe the technique and the results obtained in 53 patients.

Gelatin↗
PubMed1999

Evaluation of self-reinforced polyglycolide membrane implanted in the subcutis of rabbits.

BACKGROUND: Self-reinforced absorbable implants have been developed recently to use in hard tissue reconstructive surgery. Polyglycolide is a biocompatible polymer from which the suture Dexon is made and widely used. AIMS: To study histologically the behaviour of self-reinforced polyglycolide membrane (SR-PGA) in rabbits' ears. MATERIAL AND METHODS: SR-PGA membranes, 0.4 mm thick, were implanted in the subcutis of the ears of 24 New Zealand white rabbits. Sham operations were carried out on the contralateral ear of each rabbit. The rabbits were followed-up for 4, 12 and 20 weeks. Attention was directed towards external macroscopic changes in the rabbits' ears. After sacrifice, the ears were taken as specimens, inspected for any evidence of infection, sinus formation or fluid accumulation and histological examination was carried out. RESULTS: No complications such as infection, fluid accumulation or sinus formation were observed. Histologically, the membranes induced a foreign-body reaction involving fibrous tissue encapsulation, macrophages and giant cells. Fibrous tissue and inflammatory cells were seen between the PGA fibres. The membranes underwent progressive degradation throughout the follow-up period. However, PGA material could be still seen 20 weeks postoperatively, with a small amount of fibrous tissue and macrophages and giant cells. The implant-cartilage interface comprised fibrous and fatty tissue. CONCLUSIONS: SR-PGA membranes are biocompatible when implanted in the subcutis of the ears of rabbits.

Absorbable Implants↗
PubMed2003

Absorbable deslorelin implants (Ovuplant) prolong postpartum anestrus in early ovulating dairy cows.

Two experiments were conducted to investigate the use of a bioabsorbable implant of the GnRH agonist deslorelin to temporarily delay the resumption of postpartum ovulatory cycles in Holstein cows. In Experiment 1, recently calved cows were paired and received either a single implant (Ovuplant); Peptech Animal Health, Sydney, NSW, Australia) within 48 h of parturition (OVP; n=17), or remained as untreated controls (CON; n=17). Blood samples were collected for plasma progesterone assay three times weekly for 6 weeks to profile the pattern of resumption of ovulatory cycles. In Experiment 2, there were 15 CON and 15 OVP cows initially treated as for Experiment 1 as well as 15 OVP+SYNCH cows. Each cow in the CON and OVP+SYNCH groups received a progesterone vaginal insert (CIDR); Genetics Australia, Bacchus Marsh, Vic., Australia) for 7 days at 23 days postpartum (23 dpp) to synchronise estrus in cycling animals or to induce an ovulation with estrus in anestrus animals. Blood samples were collected weekly until removal of the CIDR insert, and then twice weekly until 56 dpp to monitor plasma P4 for retrospective determination of ovulation. Milk yield was monitored by twice daily electronic volume measurements and milk composition with once weekly milk composition analysis. In Experiment 1, CON cows began ovulating from 9 dpp; 15 of 17 had ovulated by the end of blood sampling at 42 dpp. None of the OVP cows ovulated until at least 24 dpp, and only 6 of 17 had ovulated by 42 dpp. The average day of first ovulation was extended from 22.4+/-2.7 dpp to 39.3+/-2.7 dpp (P<0.05). In Experiment 2, ovulation had occurred in 8 of 15 CON cows at the time of CIDR insertion (23 dpp), 0 of 15 OVP cows and 1 of 15 OVP+SYNCH cows. By 40 dpp (or 10 days following removal of the CIDR insert) every CON cow (15/15) had ovulated, but only 2 of 15 OVP+SYNCH cows and 1 of 15 OVP cows. None of these effects of treatment was associated with any changes in milk yield or composition in either experiment. In conclusion, inserting a bioabsorbable implant of deslorelin within 48 postpartum extended the interval to first ovulation to at least 24 dpp in 46 of 47 cows. Recovery periods were highly variable. This variability was not reduced by using a form of intravaginal progesterone supplementation that did produce a synchronised estrus with ovulation in anestrus animals that had not been treated with deslorelin.

Absorption↗
PubMed1992

Absorbable intramedullary implants for hand fractures. Animal experiments and clinical trial.

Biodegradable implants made from polyglycolic and polylactic acid co-polymers undergo degradation by hydrolysis which results in loss of their mechanical strength. The degradation of 1.5 mm polyglycolide rods (Biofix) was studied after intramedullary and subcutaneous implantation in rabbits. Two weeks after implantation there was a 73% reduction in strength of the intramedullary implants and a 64% reduction in the subcutaneous implants. Polyglycolide implants were compared with Kirschner wires for intramedullary fixation of extra-articular fractures in the hand. In one group of patients fractures were fixed with a 1.5 mm intramedullary rod and in a similar group a Kirschner wire was used. In both a wire loop was added for extra fixation. At six months there was no significant difference between the two groups. There were no allergic reactions to the polyglycolide implants.

Adolescent↗
PubMed2005

Ultra high molecular weight polyethylene and polydimethylsiloxane blend as acetabular cup material.

An acetabular cup shock absorber implant is formed from a composite of polymer materials. The cup consists of three zones such as the articulating surface of the implant is 100% ultra high molecular weight polyethylene (UHMWPE) (zone 1) and shock absorber of the cup contains of polydimethylsiloxane (PDMS) (zone 3). Zone 2 which is designed for better adhesion between zone 1 and zone 2 consists of a blend of UHMWPE and PDMS is a cushion that from one side adheres to zone 1 and the other side to zone 2. PDMS and UHMWPE have been blended under conditions of shear and elevated temperature in order to form uniform, thermoplastic blends. When blends compared to pure UHMWPE, the blends show lowered tensile modulus and lowered mixing energies. The UHMWPE crystals are increased in quantity or else become more regular, even 50% blend shows no rubbery stage. The morphology and dynamic mechanical behavior of the blends were studied using scanning electron microscopy (SEM) and dynamic mechanic thermal analysis (DMTA). In this study, the biocompatibility have evaluated in vitro the interaction of UHMWPE, silicone and PDMS/UHMWPE blends with L929 fibroblast cells.

Absorbable Implants↗
PubMed1991

Impact of the use of absorbable fracture fixation implants on consumption of hospital resources and economic costs.

Within a 6-year period (1984-1989) absorbable pins, rods, and screws made of polyglycolide, polylactide, or lactide-glycolide copolymer were used in the internal fixation of 881 fractures, 73.1% of which were displaced malleolar fractures of the ankle. During the last 3 years the patients treated using absorbable fracture fixation constituted 19.6% of all fracture patients managed by internal fixation at the department. The number of hardware removal procedures avoided during the 6-year period as a result of the use of the absorbable implants was estimated at approximately 700. By determining all direct and indirect costs associated with internal fracture fixation and the influence of the percentage of hardware removal, a cost coefficient was calculated for certain fracture types when treated using absorbable versus metallic internal fixation. In bimalleolar fractures, an optimal indication for absorbable fixation, the coefficient was 1.04 (cost of absorbable fixation 4% higher than that of metallic fixation) if the removal percentage with metallic fixation was zero and 0.91 (cost of absorbable fixation 9% lower than that of metallic fixation) if the removal percentage was 100%. The breakeven point was a removal rate of 31%.

Absorption↗
PubMed2004

Influence of test temperature and test speed on the mechanical strength of absorbable suture anchors.

PURPOSE: Absorbable implant materials offer various advantages but are mechanically far weaker than metals. Despite known temperature dependence of the biomechanical properties of these materials, mechanical testing has almost exclusively been performed at room temperature in the literature. In this study, the difference in mechanical performance at room and body temperature was assessed in vitro at different test speeds. TYPE OF STUDY: Biomechanical bench study. METHODS: Five absorbable suture anchor models were held in a metallic holder and loaded under tension using 0.5-mm steel wires until failure. Testing temperature was 20 degrees C +/- 1 degrees C or 37 degrees C +/- 1 degrees C, test speed was 50 mm/min or 5 mm/min. Tensile load at failure and failure mode were recorded. To test creep behavior, a constant load of 100 N was applied, and time to failure was recorded at both temperatures. RESULTS: Both raising the temperature and decreasing test speed significantly (P <.0001) impaired the mechanical performance of the tested implants. Increase of temperature (20 degrees C to 37 degrees C) resulted in a decrease of the maximal failure strength by up to 40% and decreased time to failure by up to 98% under static load. At 37 degrees, decreasing the test speed from 50 to 5 mm/min lowered the load to failure by up to 18%. Failure of the anchors always occurred by eyelet cutout of the wire. CONCLUSIONS: The lower the test speed, the higher is the influence of the testing temperature. Testing of implants at room temperature instead of body temperature may falsely improve test results by a factor of up to 50 under static load. Therefore, testing absorbable implants at body temperature seems mandatory, preferably at slow test speeds.

Absorbable Implants↗
PubMed1999

Bone regeneration with recombinant human bone morphogenetic protein-2 (rhBMP-2) using absorbable collagen sponges (ACS): influence of processing on ACS characteristics and formulation.

The effects of variability in three parameters (mass, cross-linking with CH2O, and EtO sterilization) of three surgically implantable absorbable collagen sponges (ACS) were studied. Sponges soaked with recombinant human bone morphogenetic protein-2 (rhBMP-2) solution were analyzed for pH, conductivity, and rhBMP-2 precipitation. A method using trinitrobenzenesulfonic acid was developed to quantify the free amino groups of the collagen sponge. With up to 240 min exposure to CH2O, the amount of free amino groups was reduced to 80%. In comparison, the denaturation temperature as determined by differential scanning calorimetry (DSC) after the sponges were soaked with phosphate-buffered saline, increased from 48 to 55 degrees C, indicating stronger interactions due to cross-linking. Subsequent sterilization with EtO caused a marked decrease in the amount of free amino groups (approximately 33% of nonsterilized controls) independent of previous CH2O treatment. However, the denaturation temperature was on average 5 degrees C lower in sterilized sponges than in nonsterilized material. In contrast to CH2O exposure, the strong reaction with EtO appeared to weaken the collagen structure. Resistance of the sponge to collagenase correlated with the degree of collagen cross-linking but was slightly reduced by sterilization. In addition, the pH of ACS soaked with water was substantially increased by sterilization. Protein precipitation was a function of pH and salt concentration but there was no effect due to collagen alone. Results indicated that ACS weight has to be limited to avoid rhBMP-2 precipitation.

Absorbable Implants↗
PubMed1988

Effects of bacterial infection on absorbable vascular ligating clips.

Electron microscopic observations of two implanted absorbable clips, Absolok and Lactomer, infected with Escherichia coli and Streptococcus faecalis, were carried out. An overgrowth of bacteria was observed over the entire surface of the clips. The mating surfaces of the Lactomer clips and the locking mechanisms of both types of clip were more heavily infected--that is, provided better support for bacterial growth--than other areas of the clips in the initial postimplantation period. However, with longer periods (up to seven days), the initial bacterial deposits developed into a thick, plaquelike layer. This layer appeared to restrict access to the surfaces such that the infected clips degraded at a much slower rate than did the noninfected clips, particularly Lactomer clips, on which little morphologic change was detectable seven days after implantation.

Animals↗
PubMed2006

[Ultrasound biomicroscopy in deep sclerectomy with a new acrylic implant].

OBJECTIVE: To describe the ultrasound biomicroscopic (UBM) characteristics seen in patients who have undergone deep phaco-sclerectomy with a new acrylic implant (Esnoper). SUBJECTS, MATERIAL AND METHODS: UBM exploration was performed 12 months after deep phaco-sclerectomy in three patients with chronic open angle glaucoma. RESULTS: One year after surgery, all three patients had intraocular pressure levels under 15 mmHg and were on no treatment. All of them had an intrascleral space in UBM, in which the hyperechogenic implant was visible. CONCLUSIONS: The new non-absorbable implant has proven to be effective in these cases. Information provided by UBM is useful and assists in understanding the mechanism of action of deep sclerectomy.

Acrylic Resins↗
PubMed1990

[The use of bioresorbable implants (Biofix) in surgery. The indications, technic and initial clinical results].

Carrying out osteosyntheses with absorbable implants is a dream cherished by traumatologists for a long time. The absorbable rods available on the medical market comply within narrow ranges with the necessary conditions with regard to stability, absorption time and biocompatibility. In our clinical department 38 osteosyntheses with Biofix rods were performed. The complication rate amounted to 13%-5 abacterial disturbances of wound healing and secretions. The indications assured so far are limited to refixation of chondral and osteochondral fragments as well as the fixation of cortical-cancellous bone grafts.

Absorption↗
PubMed2001

Guided bone regeneration for dehiscence and fenestration defects on implants using an absorbable polymer barrier.

BACKGROUND: Guided bone regeneration (GBR) using a non-absorbable barrier has provided clinicians the ability to place implants in sites compromised by insufficient bone, including immediate extraction sites. Recent evidence suggests that successful GBR outcomes may be possible using bioabsorbable polymer barriers. METHODS: This report presents a case series of 9 patients with 8 fenestration and 3 dehiscence defects on implants consecutively treated with GBR. A bioabsorbable polymer barrier of poly(DL-lactide) was used in conjunction with a composite graft of freeze-dried bone allograft (FDBA)/demineralized freeze-dried bone allograft (DFDBA) mixed in a ratio of 1:1. Second-stage surgeries were performed at 4 to 8.5 months (5. 7 months average) post-placement. Biopsy material from 2 sites was obtained while exposing the implant for healing abutment connection. RESULTS: Ten of the 11 defects (90.9%) achieved complete coverage of the osseous defects. Histologic evaluations revealed the formation of viable bone, frequently in close amalgamation with residual graft particles. CONCLUSION: These case reports suggest that a poly(DL-lactide) polymer can be used as a physical barrier with a composite bone replacement graft to achieve successful GBR results of dehiscence/fenestration defects when placing implants.

Absorbable Implants↗