Polydioxanone

in 1981, the polymer has received only limited interest until recently. The limitations of
polylactide-co-glycolide (PLGA) coupled with the growing need for materials with enhanced features
and the advent of new fabrication techniques such as electrospinning have revived interest for PDX in
medical devices, tissue engineering and drug delivery applications. Electrospun PDX mats show comparable
mechanical properties as the major structural components of native vascular extracellular matrix
(ECM) i.e. collagen and elastin. In addition, PDX’s unique shape memory property provides rebound
and kink resistance when fabricated into vascular conduits. The synthesis of methyl dioxanone (MeDX)
monomer and copolymers of dioxanone (DX) and MeDX have opened up new perspectives for
poly(ester-ether)s, enabling the design of the next generation of tissue engineering scaffolds for application
in regenerating such tissues as arteries, peripheral nerve and bone. Tailoring of polymer properties
and their formulation as nanoparticles, nanomicelles or nanofibers have brought along important developments
in the area of controlled drug or gene delivery.
This paper reviews the synthesis of PDX and its copolymers and provides for the first time an exhaustive
account of its applications in the (bio)medical field with focus on tissue engineering and drug/gene
delivery.

The hydrolytic degradation of bioabsorbable polydioxanone (PPDX) was studied in a phosphate bu€er solution, pH=7.4, 37 C. The degradation was evaluated by analyzing the changes in the elastic modulus and morphological changes. After 10 weeks, the weight loss, pH and molecular weight changes suggested di€usion of low molecular weight chain segments into the reaction medium as a consequence of the breaking of ester bonds in the material. The crystallinity (X c) increased with hydrolysis time, indicating the ®rst step of the degradation process. Modulus was found to decrease, indicating that chain scission proceeded in two steps: the ®rst occurring in the amorphous regions of micro®brils and intermicro®brillar space; the second in the crystalline regions, resulting in a lower stress value for the chain segments when submitted to external forces. Surface morphological changes suggest a heterogeneous degradation mechanism by layers. #

To test the integrity of knots tied with expired suture and non-expired suture, using 5 different suture materials.Knots were tied using expired and non-expired chromic catgut, polyglactin 910, polydioxanone, silk, or coated polyester. Expired sutures were a mean of 10.5 years past the date of expiration stamped on the packaging. Suture packaging was inspected for any flaws or humidity. There were 116 knots with expired suture and 109 non-expired knots. All knots were tied by hand. Suture was soaked in 0.9% sodium chloride for 60 seconds and subsequently transferred to a tensiometer where the tails of the knots were cut to 3 mm length. We compared the tensile strength of knots using a tensiometer to pull the knots until the suture broke or untied. A minimum of 30 knots were needed in order to detect a statistically significant main effect for expired and non-expired sutures with 80% power and a 5% chance of type I error.A total of 225 knots were tied. Overall, we found no difference in mean tension between expired suture (77.5 ± 31.7 N) and non-expired suture at failure (81.9 ± 30.2 N). All the sutures broke at the knot and none untied. Expired chromic and polydioxanone were significantly weaker than the non-expired suture of the same material (p = 0.002 and p = 0.001, respectively). There was no statistically significant difference in tensile strength between expired absorbable or permanent suture materials. Based on a univariate analysis of variance ([SCAP]ANOVA)[R] there was no difference in the tension at failure between expired and non-expired sutures with suture packet as a covariate. No suture untied when knotted with expired suture.Under laboratory conditions, expired chromic and polydioxanone sutures broke at lower tensile strength than non-expired sutures of the same material.

Background:  Median laparotomy is the most common approach to the abdominopelvic cavity in patients with gynaecological tumours.Aims:  The primary endpoint of the study was to evaluate the onset of incisional hernia. The secondary endpoint was to evaluate the onset of infection, wound dehiscence, wound infection, and scar pain during the post-operative period.Methods:  A total of 191 patients were eligible for the study. They were divided into three groups. Group A underwent en bloc closure of the peritoneum and fascia with Premilene® suture, Group B en bloc closure of the peritoneum and fascia with Polydioxanone suture, and Group C separate closure of the peritoneum and fascia with single stitches of Ethibond suture. Statistical analysis was performed using the Statistical Software Package for Social Sciences 12.0.Results:  Group A and Group B comprised 63 patients, and Group C included 65 patients. The three groups proved homogeneous on statistical analysis (P > 0.05). The statistical analysis did not reveal significant differences between the different suture types and techniques with respect to the incidence of incisional hernia (P > 0.05).Conclusion:  In our study, the incidence of incisional hernia was 8%. Randomised patients were homogeneous for sample size and risk factors. No significant differences were found between suture types or techniques. Currently, there is no suture material or technique that can be considered superior to others. When possible, we believe that the best way to prevent incisional hernia is to preserve the integrity of the abdominal wall using minimally invasive techniques.

Rotator cuff tendon pathology is thought to account for 30-70 % of all shoulder pain. For cases that have failed conservative treatment, surgical re-attachment of the tendon to the bone with a non-absorbable suture is a common option. However, the failure rate of these repairs is high, estimated at up to 75 %. Studies have shown that in late disease stages the tendon itself is extremely degenerate, with reduced cell numbers and poor matrix organisation. Thus, it has been suggested that adding biological factors such as platelet rich plasma (PRP) and mesenchymal stem cells could improve healing. However, the articular capsule of the glenohumeral joint and the subacromial bursa are large spaces, and injecting beneficial factors into these sites does not ensure localisation to the area of tendon damage. Thus, the aim of this study was to develop a biocompatible patch for improving the healing rates of rotator cuff repairs. The patch will create a confinement around the repair area and ...

The healing of midline laparotomy incisions closed with a continuous suture of nylon or second-generation polydioxanone was evaluated in a randomized clinical trial. The effect of suture technique, reflected in the suture length to wound length ratio, was also assessed. All patients who underwent abdominal surgery through a midline incision were included except those with incisional hernia after previous midline operation. Wound dehiscence occurred in five (0·6 per cent) of 813 patients and wound infection in 73 (9·0 per cent). These rates were similar for both suture materials, as were those for the development of suture sinus and prolonged postoperative wound pain. Incisional hernia 12 months after surgery was found in 49 (15·1 per cent) of 325 wounds sutured with polydioxanone and in 50 (15·7 per cent) of 318 closed with nylon (P=0·91). There was a significant correlation between the hernia rate and the suture to wound length ratio for both materials (P<0·001). These results i...

Surgical harvest of Xenopus laevis oocytes for developmental research is a common procedure that requires closure of a 0.5- to 2.0-cm incision with suture material. Although such harvests are a frequent practice, little published information exists to provide guidance regarding the most appropriate suture material for wound closure in laboratory amphibians. To determine which suture material elicits the least response in amphibian skin, we used Xenopus laevis as a model to investigate the gross and histologic tissue reactions to 5 commonly used suture materials-3-0 silk, monofilament nylon, polydioxanone, polyglactin 910, and chromic gut. The skin reacted in 3 ways to suture material, showing edema, epidermal changes, and inflammation. Although the gross reactions to monofilament nylon, polydioxanone, and polyglactin 910 were clinically indistinguishable and were associated with lowest gross reaction scores, monofilament nylon elicited the least histologic reaction and therefore see...

Suture materials are widely used in urological surgery especially in regions that are in contact with urine. In this study, we aimed to compare polyglactine 910, cromed catgut and polydioxanone sutures according to stone formation and inflammation, congestion and foreign body reaction that occur on bladder mucosa. Cystotomy procedure was performed, in three groups of Wistar female rats, with 4/0 polyglactine 910, 4/0 chromed catgut and 4/0 polydioxanone sutures. All groups were divided into two sub-groups with 4 and 8-week follow up periods. Rats were treated with 20 mg kg−1 day−1 Ofloxacin (i.p.) daily until the seventh post-operative day. Urinary pH, leucocyte esterase and nitrite levels were determined. All rats were killed at the end of the follow-up period and stone formation on sutures and degrees of tissue reactions (inflammation, congestion and foreign body reaction) on bladder mucosa were compared. Tissue reactions were evaluated by the same pathologist (S. K.). Chi-square and Student’s t test were used in statistical analysis (p p > 0.05). Although the difference between the degrees of congestion in groups was not statistically significant (p > 0.05), there were statistically significant differences between the degrees of inflammation and foreign body reaction in groups. Although the duration of urinary contact of suture is the main factor in stone formation on suture material, tissue reaction on mucosa and the physical structure of suture also affect this formation. We observed lower degrees of inflammation and foreign body reaction with 4/0 polydioxanone and no stone formation. We believe that polydioxanone may be useful and reliable in urological surgery due to these properties.

Since the commercialization of polydioxanone (PDX) as a biodegradable monofilament suture by Ethicon in 1981, the polymer has received only limited interest until recently. The limitations of polylactide-co-glycolide (PLGA) coupled with the growing need for materials with enhanced features and the advent of new fabrication techniques such as electrospinning have revived interest for PDX in medical devices, tissue engineering and drug delivery applications. Electrospun PDX mats show comparable mechanical properties as the major structural components of native vascular extracellular matrix (ECM) i.e. collagen and elastin. In addition, PDX's unique shape memory property provides rebound and kink resistance when fabricated into vascular conduits. The synthesis of methyl dioxanone (MeDX) monomer and copolymers of dioxanone (DX) and MeDX have opened up new perspectives for poly(ester-ether)s, enabling the design of the next generation of tissue engineering scaffolds for application in...

The aim of the study was to compare synthetic monofilament suture materials with chromic catgut and silk in aural wound closure. Forty patients undergoing mastoidectomy or tympanoplasty were randomized to closure with either 30 PDS (Polydioxanone) to fascia plus 30 Prolene to skin, or 20 chromic catgut to fascia plus 30 silk to skin. Known or suspected factors affecting wound healing were recorded. Nine patients had post-operative wound infections. The infection rate was significantly lower in wounds closed with PDS and Prolene (χ2 = 6.05, p

Purpose Hernias can be repaired by reinforcement of damaged fascia using biomaterials to provide stabilisation. Repair materials are usually porous, through which cells infiltrate, proliferate and secrete ECM. Their efficacy relies on good tissue integration and resolution of host defence mechanisms. Therefore, understanding the dynamics by which biomaterials interact with tissue will provide knowledge to advance prosthesis design. Furthermore, determining host response in real time would provide significant advantage both clinically and scientifically over the current terminal process of histology. Methods 3 materials comprising synthetic and composite (synthetic materials hybridised with a resorbable biologic component) meshes were implanted into a rat full-thickness abdominal wall excision model. Their efficacy was evaluated using histopathology whilst also monitoring systemic concentrations of cytokines associated with inflammation and wound healing to predict material outcome o...

Actinomyces naeslundii has been recovered from traumatized permanent teeth diagnosed with necrotic pulps. In this work, a triple antibiotic paste (TAP)-mimic scaffold is proposed as a drug-delivery strategy to eliminate A. naeslundii dentin biofilm. Metronidazole, ciprofloxacin, and minocycline were added to a polydioxanone (PDS) polymer solution and spun into fibrous scaffolds. Fiber morphology, mechanical properties, and drug release were investigated by using scanning electron microscopy, microtensile testing, and high-performance liquid chromatography, respectively. Human dentin specimens (4 × 4 × 1 mm(3), n = 4/group) were inoculated with A. naeslundii (ATCC 43146) for 7 days for biofilm formation. The infected dentin specimens were exposed to TAP-mimic scaffolds, TAP solution (positive control), and pure PDS (drug-free scaffold). Dentin infected (7-day biofilm) specimens were used for comparison (negative control). Confocal laser scanning microscopy was done to determine bacte...

A new type of in vivo tissue engineering system for tendon repair in situ after cut or crush of a flexor tendon is described. The system is based on the topographical reaction, alignment, migration and perhaps proliferation of tendon cells on micrometrically grooved substrates made in a biodegradable polymer. Macrophage trapping in the structure may also help to prevent inflammation. Tendon damage including crush and section injury is a fairly frequent occurrence. The conventional treatment is surgical repair, however frequently this leads, especially in hand wounds, to attachment of the tendon surface to the surrounding synovium, which is very undesirable. We present an approach based on using a biodegradable device to ensure that the healing of severed or crushed flexor tendons is aided, synovial adhesion prevented and the final result anatomically correct. The biodegradable sheath carries microgrooves fabricated into the polymer by embossing that orient and guide the cells toward...

Eliminating and/or inhibiting bacterial growth within the root canal system has been shown to play a key role in the regenerative outcome. The aim of this study was to synthesize and determine in vitro both the antimicrobial effectiveness and cytocompatibility of bimix antibiotic-containing polydioxanone-based polymer scaffolds. Antibiotic-containing (metronidazole [MET] and ciprofloxacin [CIP]) polymer solutions (distinct antibiotic weight ratios) were spun into fibers as a potential mimic to the double antibiotic paste (DAP, a MET/CIP mixture). Fiber morphology, chemical characteristics, and tensile strength were evaluated by scanning electron microscopy, Fourier transform infrared spectroscopy, and tensile testing, respectively. Antimicrobial efficacy was tested over time (aliquot collection) against Enterococcus faecalis (Ef), Porphyromonas gingivalis (Pg), and Fusobacterium nucleatum (Fn). Similarly, cytotoxicity was evaluated in human dental pulp stem cells. Data were statisti...

Objective  To compare two surgical techniques and two types of suture material for anal sphincter repair after childbirth-related injury.Design  Factorial randomised controlled trial.Setting  Tertiary referral maternity unit.Population  Women with an anal sphincter injury sustained during childbirth.Method  Women were randomised into four groups: overlap repair with polyglactin (Vicryl); end-to-end repair with polyglactin (Vicryl); overlap repair with polydioxanone (PDS); and end-to-end repair with PDS. All repairs were completed as a primary procedure by staff trained in both methods.Main outcome measures  Suture-related morbidity at six weeks. Bowel symptoms at 3, 6 and 12 months. Anorectal physiology at three months. Quality of life scores at 3 and 12 months.Results  One hundred and fifty women (1.5% of deliveries) were eligible and 112 (75%) were randomised. One hundred and three (92%) attended follow up visit at 6 weeks, 89 (80%) at 3 months, 79 (71%) at 6 months and 60 (54%) at 12 months. At six weeks, there was no difference in suture-related morbidity between groups (P= 0.11) and 70% patients were completely asymptomatic. Incidence of bowel symptoms and quality of life disturbances were low, with no differences between the four groups.Conclusion  Obstetric anal sphincter repair carried out by appropriately trained staff is associated with low morbidity, irrespective of the suture material and repair method used.