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PubMed1995

Influence of soluble suture factors on in vitro macrophage function.

Suture materials may interact with immune competent cells and thereby affect localized immunity. Macrophages are central to the inflammatory response and coordinate wound healing. They are also involved in the clearance of foreign material, bacteria and malignant cells. We studied the influence of soluble factors associated with silk, steel, nylon, polyglactin, polydioxanone and chromic catgut sutures on macrophage adherence, phagocytosis and the production of lysozyme and tumour necrosis factor. Soluble factors from suture materials influenced macrophage behaviour in vitro causing cellular activation, functional impairment and alterations in secreted levels of the cytokine tumour necrosis factor and the bactericidal agent lysozyme. Of the six materials studied, polyglactin had the most extreme effect, causing significant inhibition of cell adherence and lysozyme production. Silk also exerted a considerable effect on macrophages, significantly inhibiting adherence. In contrast, steel and polydioxanone media caused minimal inhibition of macrophage function although, as with all materials, they did activate the cells. This study has demonstrated that sutures release immunotoxic factors which considerably influence macrophage behaviour in vitro. These effects may have important clinical implications.

Animals↗
PubMed2003

Factors involved in abdominal wall closure and subsequent incisional hernia.

Incisional hernia is a frequent complication of abdominal wall closure with a reported incidence of between 5% and 15% following vertical midline incisions at one-year follow-up. Evidence from randomised clinical trials and meta-analysis indicate that a continuous running non-absorbable or slowly absorbed suture such as polydioxanone is the method of choice for abdominal wall closure. Continuous polydioxanone has a similar incisional hernia rate to its non-absorbable counterparts but causes less chronic pain and wound sinuses. Evidence from randomised clinical trials indicates that a lateral paramedian incision is associated with a lower incidence of incisional hernia when compared with other abdominal incisions. Transverse abdominal incisions have no advantage over midline incisions in reducing incisional hernia rate. Although experimental and clinical evidence indicate that a greater number of stitches with a suture length to wound ratio of at least 4:1 is associated with a lower incidence of incisional hernia, there is no evidence from randomised clinical trials to support this. Intuitively one may think that putting as little tension as possible on the closure is important, but there is no evidence for this. Clinical trials evaluating these factors would be difficult to undertake making it important that surgeons continue to audit incisional hernia rates following abdominal closure.

Abdominal Wall↗
PubMed1997

The role of macrophages in bioartificial nerve grafts based on resorbable guiding filament structures.

A 10 mm gap in a rat sciatic nerve was bridged by a bioartificial nerve graft consisting of a silicone tube containing seven longitudinally placed filaments made of non-resorbable material (polyamide [Ethilon]) or resorbable materials (polydioxanon [PDS], polyglactin [Vicryl] or catgut). The purpose was to study the tissue reaction induced by the four different types of materials. At 4 weeks an immunocytochemical technique, using ED1 and ED2 monoclonal antibodies, was used to study the presence and location of macrophages. A large number of macrophages were found accumulating on the surface of catgut and polyglactin, while few were found on the surface of polyamide and polydioxanon filaments. It is concluded that the cell layers on the filament surface mainly consisted of ED1 positive cells and their thickness depends on the filament materials.

Journal Article↗
PubMed2003

Failure characteristics of various arthroscopically tied knots.

The current study evaluated multiple arthroscopic knot configurations and compared their properties with open, hand-tied square knots. This is an experimental study done on a material testing system. Number 2 Ethibond Extra and Number 1 Polydioxanone sutures were used. Four types of sliding knot configurations were tested: the Duncan loop, the Tennessee Slider, the Savoie-Modified Roeder, and the Lieurance-Modified Roeder. Two types of nonsliding knots were tested: the Revo knot and a knot consisting of alternating half-hitches tied with the Sixth Finger Knot Pusher. Ten knots were tied of each configuration, using strict arthroscopic technique. Each knot was backed-up with four half-hitches using post switching technique. Knots were tied around two rings and then transferred wet to a materials testing machine. The knots were tested until ultimate failure, with note of clinical failure at 3 mm. Ethibond suture using the Revo knot, the Lieurance-Modified Roeder knot, and the Savoie-Modified Roeder knot were similar in strength to the square knot with comparable failure modes. Polydioxanone suture was more variable; the Revo knot, the Savoie-Modified Roeder, the Tennessee Slider, and the Duncan loop were comparable with hand-tied square knots. All of the open and arthroscopic suture loops tested in this study failed by the suture loops expanding to greater than 3 mm before ultimate failure occurred. The surgeon choosing arthroscopic repair techniques should be aware of the differences in suture material and the variation in knot strength afforded by different knot configurations.

Arthroscopy↗
PubMed2002

Three-dimensional endoscopic midface enhancement: a personal quest for the ideal cheek rejuvenation.

Standard face-lift techniques are excellent for the treatment of the jawline and neck. Treatment of the area between the lower eyelid and the corner of the mouth required the development of techniques in the intermediate lamella of the face. Alternative techniques of subperiosteal dissection by means of lower eyelid incisions were described with good aesthetic results but at the expense of increased morbidity and complications. All these techniques were also two-dimensional manipulations of the soft tissues of the face. The author presents a different approach that he believes is close to the ideal in terms of safety, morbidity, and complications. Although midface rejuvenation may be performed alone, it is more commonly done as a component of total facial rejuvenation. The midface is approached by means of a combination of a temporal slit incision and an upper oral sulcus incision; no eyelid access is used. Fifty percent of the midface dissection is performed under direct visualization, and 50 percent is performed under endoscopic control. Dissection of the temporal area is done under the temporoparietal fascia down to the zygomatic arch. The anterior two-thirds of the zygomatic arch periosteum is elevated along with a few millimeters of the intermediate temporal fascia and the fascia of the masseter muscle. The subperiosteal dissection of the zygoma and maxilla is completed with the medial extension of the dissection just medial to the infraorbital nerve. The orbital fat pads are released by means of intraoral route, and the lateral and middle fat pads are advanced over the orbital rim and fixed to the masseter tendon and the periosteum of the maxillary shelf at the intraoral incision. Three suspension points are typically used on the midface, each one with a different action. All are anchored to the temporal fascia proper. The vascularized Bichat's fat pad is mobilized and fixed with 4-0 polydioxanone sutures. This provides a volumetric cheek augmentation and improvement of the jowl. The inferior malar periosteum and fascia is used for malar imbrication with 4-0 polydioxanone sutures. This provides an anterior projection of the cheek and elevates the corner of the mouth. The suborbicularis oculi fat is used for en bloc vertical suspension of the cheek. This also improves the infraorbital V deformity. This technique has been used in close to 200 patients over the last 5 years. The complications have been minimal: two cases of temporary paresis of the levator of the upper lip, one case of paresis of the orbicularis oris (unilateral), one case of buccinator muscle dysfunction, and two moderate infections that were treated with simple drainage. The degree of facial edema has been minimal compared with the open or the transblepharoplasty approach. Typically, patients can return to work 2 weeks after surgery.The three-dimensional endoscopic midface enhancement provides a technique of midface remodeling that provides the missing dimension (volume) to the rejuvenation of the midface. This can be done with a minimal rate of complications, and the aesthetic results surpass by far the results of other midface techniques previously described by the author.

Adult↗
PubMed2004

Endoscopic brow lift: a personal review of 538 patients and comparison of fixation techniques.

Since the introduction of endoscopic brow lifting in the mid-1990s, it has become widely accepted as a method for rejuvenation of the upper third of the face. Despite the multitude of brow fixation techniques, there are few long-term studies providing accurate analysis of outcome. The aims of this investigation were to evaluate the long-term objective results of endoscopic brow lifting and to establish whether the technique of fixation altered the longevity of aesthetic outcome. The outcome of endoscopic brow lifts carried out on 538 consecutive patients over a 6-year period was assessed. For each patient, midpupil-to-brow distance was measured preoperatively and at intervals postoperatively. Two different fixation methods were compared: fibrin glue (n = 189, group 1; 104 records available) and polydioxanone sutures tied through bone tunnels (n = 349, group 2; 220 records available). In 214 patients, an upper lid blepharoplasty was performed simultaneously (85 in group 1 and 129 in group 2). At 1 month postoperatively, each fixation technique had produced a significant change in mean pupil to brow height (5.93 mm in group 1 and 6.21 mm in group 2, with no significant difference between the two methods; p = 0.17). However, when measurements were compared more than 3 months postoperatively (mean, 9.4 months), there was a significant difference, with some relapse in the patients treated with fibrin glue (p < 0.01). However, in group 2 (tunnel fixation), measurements remained stable, with 6.21 mm at 1 month compared with 6.16 mm long term (no significant difference, p = 0.34). In contrast, in group 1 (fibrin glue), measurements showed significant reduction, with a 1-month result of 5.93 mm and a long-term outcome of 3.79 mm (p < 0.01). Upper lid blepharoplasty had no effect on the long-term outcome of either group (p > 0.3 in group 1, p > 0.4 in group 2). Complications were few in both groups. In group 1, there was one infection, two instances of significant alopecia (both temporary), and one reoperation for relapse. In group 2, four patients required minor surgical revision of a lateral port scar and three minor areas of temporal alopecia, which recovered in less than 3 months. One patient had a paresis of the frontal branch that had recovered after 4 months. The endoscopic brow lift is therefore a safe and effective technique for increasing mean pupil to brow height. Fixation with polydioxanone sutures tied through bone tunnels produces a significantly more stable result than fibrin glue, without greater risk. This lends weight to experimental evidence that periosteal fixation must be maintained for at least 6 weeks to be secure.

Blepharoplasty↗
PubMedDate not supplied

Evaluation of an autologous tendon graft repair method for gap healing of the deep digital flexor tendon in horses.

A sutured tenorrhaphy technique that incorporated an autologous tendon graft was compared mechanically and histologically with a sutured tenorrhaphy at 6, 12, and 24 weeks after repair. Tenorrhaphy was performed in the forelimb tendon of the deep digital flexor muscle and the graft was taken from the hindlimb tendon of the lateral digital extensor muscle; one forelimb site included the graft, whereas the other forelimb site was not grafted. Tenotomies were made immediately proximal to the insertion of the accessory ligament into the tendon of the deep digital flexor muscle. Grafted and nongrafted tenorrhaphies were sutured with 2 polydioxanone in a modified double locking-loop pattern. Limbs were supported with a bandage and an extended elevated heel shoe that maintained the dorsal hoof wall angle at 70 degrees to 75 degrees; this support was removed at 12 weeks and dorsal hoof wall angle was maintained at 40 degrees to 45 degrees for the remainder of the study. Gap formation (2.5 +/- .3 cm) was evident at all tenorrhaphy sites at 3 days on ultrasound examination. In grafted repairs, the breaking stress was increased (P < .001) between 6 weeks (2.56 +/- .44 MPa) and 12 weeks (17.69 +/- 7.68 MPa), with grafted tendon having a greater breaking stress than nongrafted tendon (8.77 +/- 2.5 MPa; P < .05). No differences in breaking stress were evident at 24 weeks. At 12 weeks, repair tissue in grafted tendon was histologically more mature, had less cellularity, better fibroblast orientation and more homogeneous collagen matrix than nongrafted tendon. Polydioxanone suture was still evident histologically at 24 weeks and was associated with minimal cellular reaction. Incorporation of an autologous tendon graft improved the mechanical properties and histological quality of the repair tissue in equine flexor tenorrhaphies at 12 weeks but not at 24 weeks after repair.

Animals↗
PubMedDate not supplied

Biomechanics of the coracoclavicular ligament complex and augmentations used in its repair and reconstruction.

Augmentation is a well-accepted and common component of coracoclavicular ligament repairs and reconstructions. The purpose of this study was to examine and compare the strength, stiffness, and mode of failure of the coracoclavicular ligament complex and four different augmentation techniques in cadaveric shoulders. There was no significant difference in the mean failure load between the intact ligament complex (724.9+/-230.9 N) and augmentations performed with braided polydioxanone (PDS) (676.7+/-115.4 N) or braided polyethylene placed through (986.1+/-391.1 N) or around (762.7+/-218.2 N) the clavicle. The mean failure load for augmentations using a 6.5-mm cancellous screw through the clavicle and into a single cortex of the coracoid (390.1+/-253.6 N) was significantly lower than that for the intact coracoclavicular ligaments. There was no difference in mean stiffness between the intact coracoclavicular ligament complex (115.9+/-36.2 N/mm) and the braided polyethylene augmentations placed through (99.8+/-22.2 N/mm) or around (90.0+/-25.5 N/mm) the clavicle. Polydioxanone augmentations were significantly less stiff (27.4+/-3.3 N/mm) than the intact complex, while screw augmentations were significantly stiffer (250.4+/-88.2 N/mm). There were no significant differences in strength or stiffness of braided polyethylene reconstructions placed around or through a drill hole in the clavicle.

Acromioclavicular Joint↗
PubMed1987

The combined anterior cruciate and medial collateral ligament replacement by various materials: a comparative animal study.

On 30 sheep, a combined replacement of the anterior cruciate and medial collateral ligament of the right knee was performed with four different materials. Dacron prostheses and glutaraldehyde-preserved bovine tendon prostheses as well as braided ligament prostheses made of carbon fibers and braided resorbable polydioxanone fibers surrounded by lyophilized dura in their intra-articular part were used. Ten unoperated sheep served as a control group. After 1 year the animals were sacrificed and the knee joints were explanted and biomechanically as well as histomorphologically investigated. The gross inspection of the joints showed no ruptured medial collateral ligament replacement but did show partially and totally ruptured anterior cruciate ligament replacements. The Dacron prosthesis was broken in 50% of the cases, whereas for the other materials one ruptured ligament replacement each (12.5%) could be observed. The anterior drawer test and the determination of the tensile stiffness of the remaining ligament replacements revealed that none of the operated knees achieved the properties of the normal control knees. However, the carbon fiber implants had the best result of all prostheses tested. For all materials except the resorbable polydioxanone, abrasion particles could be found in the anterior cruciate ligament and in the synovial membrane. The tissue reaction to these particles was a mild synovitis for carbon fragments, a strong synovitis for Dacron particles, and a chronic inflammatory response to bovine tendon fragments with macrophage granulomas and fibrosis.

Animals↗
PubMedDate not supplied

Physical properties of self locking and conventional surgical knots.

OBJECTIVE: To assess some of the physical properties of three types of self locking knots and two types of conventional surgical knots. DESIGN: Experimental in vitro study. OUTCOME MEASURES: Knot efficiency (knot strength: suture strength ratio), slippage, and volume. MATERIALS: Test knots tied with the suture materials polyglactin, polydioxanone and nylon in USP sizes 1,2/0, and 4/0. RESULTS: Self locking knots performed significantly better (p < 0.01) than conventional knots in all combinations of material and size, except for 4/0 nylon. Efficiency of the self locking knots tied with the monofilament polydioxanone and nylon ranged from 0.88-0.96. With the multifilament polyglactin, it ranged from 0.71-0.90, and it increased proportionally with the thickness of the material. The mean efficiency of the conventional knots was 0.51 (0.06) for polyglactin, and 0.70 (0.17) for the monofilament materials. The self locking knots did not slip. The conventional starting knot often slipped partly, but came undone only when the conventional terminating knot was tied with monofilament material. The self locking knots were significantly smaller than the conventional knots. CONCLUSION: Self locking knots are safer than conventional surgical knots, and considerably smaller.

Humans↗
PubMed1999

Prevention of Frey syndrome during parotidectomy.

OBJECTIVE: To evaluate the incidence of Frey syndrome (auriculotemporal nerve syndrome) after parotidectomy with and without placement of a subcutaneous implant and to examine the relationship between different implants and postoperative wound complications (hematoma, seroma, salivary fistula). DESIGN: A prospective nonrandomized controlled trial. SETTING: A primary care and referral university hospital center. PATIENTS: All patients scheduled for parotidectomy from April 1994 through August 1998 were eligible. Seventy patients were enrolled (2 refused). All 70 patients were evaluated for wound complications. Sixty patients with a follow-up of more than 1 year were evaluated for Frey syndrome. INTERVENTION: The choice of implant was left to the individual surgeon: 24 patients had no implant; 7, lyophilized dura implant; 7, polyglactin 910-polydioxanone (Ethisorb) implant; and 32, expanded polytetrafluoroethylene (e-PTFE) implant. OUTCOME MEASURES: The incidence of Frey syndrome was evaluated (1) subjectively by history (clinical Frey syndrome) and (2) objectively by using 2 newly developed tests. Both hemifaces were tested, with the normal side being used as a control. RESULTS: Clinical Frey syndrome was present in 12 patients: 11 without implants (11/24 [53%]) and 1 with an implant (1/46 [2%]) (P<.001). Objective tests were positive in 24 patients: 16 (76%) of 21 without implants and 8 (20%) of 39 with implants (P<.001). In the implanted patients, the objective tests were positive in 71% (5/7) of those with lyophilized dura, 14% (1/7) of those with Ethisorb, and 8% (2/29) of those with e-PTFE implants (P<.001). Wound complications included hematoma in 5 patients (7%), seroma in 4 patients (6%), and salivary fistula in 15 (21%). Salivary fistula occurred more frequently with Ethisorb (57%) and e-PTFE (25%) implants (P = .04). CONCLUSIONS: In patients without an implant, the incidence of Frey syndrome is 50% for subjective and 80% for objective evaluation. In patients with an implant, these incidences are 3% and 10%, respectively. Some implants are associated with a higher incidence of salivary fistula.

Adolescent↗
PubMed2000

Clinical and histological results of septoplasty with a resorbable implant.

BACKGROUND: The use of a resorbable implant connected with septal cartilage would facilitate external septoplasty, offering mechanical stability until the cartilage fragments heal. OBJECTIVE: To study the histological and clinical results of septoplasty with a resorbable implant (polydioxanone [PDS; Ethicon, Norderstedt, Germany]) in conjunction with cartilage. DESIGN: To provide histological information in 5 rabbits, PDS foil was implanted into the outer ear in conjunction with an artificial cartilage defect. Observations were made at 2, 5, 10, 15, and 25 weeks. Resorption of the implant was investigated, including the time to complete elimination. In addition, septoplasty with PDS foil was performed on 71 patients with severe septal deformities. Surgery consisted of excision of the quadrilateral cartilage and division into straight fragments, which were sutured to the PDS foil and replaced as a free graft. SETTING: Ear, nose, and throat department of the General District Hospital Steyr, Steyr, Austria. RESULTS: Histological examination showed that the foil remained unchanged for at least 10 weeks and was completely resorbed after 25 weeks with minimal remaining scar tissue. Newly formed cartilage developed bordering the cartilage defect. In the clinical study, all patients experienced varying degrees of improvement in nasal blockage. No immediate or long-term complications occurred. CONCLUSIONS: The use of PDS foil in connection with cartilage facilitates surgical correction of severe septal deformities, additionally providing support for the nasal dorsum. The histological examination showed that no inflammatory or foreign body reaction occurred. Cartilage regeneration was even found. The foil was completely resorbed within 25 weeks, avoiding the long-term complications that occur with other artificial implants.

Absorbable Implants↗
PubMed2000

Clinical and histological findings in guided bone regeneration (GBR) around titanium dental implants with autogeneous bone chips using a new resorbable membrane.

The aim of this study was to test the value of a polydioxanon-membrane (PDS(R), Ethicon, Norderstedt, Germany) in combination with autogenous bone as a spacer for guided bone regeneration of denuded implant surfaces in comparison to simple augmentation. Altogether, in 8 Beagle dogs of 12 months, the three mandibular premolars were extracted on both sides and, after an uneventful healing of the extraction sockets in each mandibular site, two seize defined bone defects were produced. The defects were 7 mm long, had a vertical extension of 7 mm, and were 7 mm deep. These also included, therefore, the resection of the lingual cortical bone wall. In the center of all these 32 bone defects, Brânemark fixtures with a diameter of 3 mm and a length of 10 mm were implanted. Every implant was primarily stable due to the fixation in the native bone under the created defects. In each mandible site, one bone defect was filled with autologous bone resulting from the previous defect preparation. Half of the defects were covered with a PDS membrane, and the other half were covered only by the relocation of the mucoperiosteal flap. During the observation period of 90-180 days, continuous clinical and radiological controls were executed. Aside from the observed clinical healing problems in the test sites, such as exposure of the membranes and serious inflammatory reactions, the histological and radiological results of the control group regarding bone regeneration were superior to these of the test group, which were valid also for the subgroups with or without autologous bone fillings.

Animals↗
PubMed1993

Continuous single-layer serosubmucosal anastomosis in the upper gastrointestinal tract.

In a 4-year period, 100 anastomoses in the upper gastrointestinal tract were fashioned using a single serosubmucosal layer of continuous polydioxanone. One patient required revisional surgery because of anastomotic stricture after partial gastrectomy, but there was no other complication related to the anastomosis. This technique is simple, safe, and quick to perform.

Anastomosis, Surgical↗
PubMed1988

A comparative scanning electron microscopic study on degradation of absorbable ligating clips in vivo and in vitro.

Using scanning electron microscopy, the degradation characteristics of two absorbable ligating clips, Absolok (polydioxanone) and Lactomer (poly-L-lactide-co-30%-glycolide) have been studied under in vivo and in vitro conditions. The rate of Absolok clip degradation was significantly greater than that of Lactomer clip degradation both in vitro and in vivo. The rate of degradation of Lactomer clips significantly increased and they showed a greater change in proportion of breakdown in vivo than in vitro compared to Absolok clips. The Absolok clip breakdown began with the formation of surface undulations which later developed into fissures. The undulations appeared on the clip surface as early as 7 days and by 2 weeks developed into fissures. The initial appearance of the fissures was at the edge of the clips particularly at the mating surface. The thickness of layers forming the fissures gradually decreased and by 15 weeks the layers appeared as very thin sheets of materials. The high energy areas (locking and molding points) were more resistant to breakdown and the remains of the clips were still present 25 weeks after initiation of the experiments. The Lactomer clips showed very little sign of degradation in vitro even after 10 weeks of incubation. However, in the in vivo experiments undulations formed on the clip surface as early as 2 weeks postimplantation. These clips also showed fissures similar to those observed on Absolok clips.

Animals↗
PubMed1993

Kinetics of cell proliferation as a function of vascular graft material.

Bioresorbable vascular grafts constructed for polyglactin 910 (PG910) and polydioxanone (PDS) and nonresorbable Dacron were interposed into the infrarenal abdominal aortas of New Zealand White rabbits. The prosthesis/tissue complexes were harvested after 2, 3, 4, 12, and 52 weeks. Seventeen, 9, and 1 h prior to sacrifice, animals received tritiated thymidine (0.5 mCi/kg/dose). All specimens were studied grossly and by light and transmission electron microscopy. Mitotic indices (MI's) were determined by autoradiography for inner capsule myofibroblasts at the proximal, mid, and distal segments of each prosthesis. There were no aortic-related deaths. All grafts were patent with no aneurysmal dilatation. At 4 weeks, PG910 resorption was evidenced by macrophage phagocytosis, less so in PDS while Dacron remained intact. At 12 weeks, the PG910 was completely resorbed while PDS resorption continued. The latter was completely resorbed by 52 weeks. There was no significant difference in MI's between proximal, mid, and distal regions for each graft type. The mitotic index paralleled the rate of prosthetic resorption in both PG910 and PDS groups, as high as 28.34 +/- 23.21 in the former 3 weeks after implantation and significantly higher at 4 weeks (7.58 +/- 2.02 and 7.50 +/- 2.66, respectively) than at 52 weeks (0.72 +/- 0.98 and 1.00 +/- 0.22, respectively) in both groups. The mitotic index in the Dacron group never surpassed 1.22 +/- 0.90. We conclude that higher levels of early cell proliferation in bioresorbable grafts closely parallel the kinetics of prosthetic resorption.

Animals↗
PubMed1993

Determination of the 3-D morphology of degradable biopolymer implants undergoing in vivo resorption.

A technique is presented that allows the visualization of the degradation process of biopolymers. Serial thick-section specimens containing cross-sections of polydioxanone implants (PDAs) were realigned for 3-D reconstruction using a double-embedding technique. The outlines of the cross-sectioned implants were traced using an automatic image analysis system and converted into x, y, and z coordinates. The reconstruction of the implant body was achieved by the stepwise analysis of vertical relationships between two adjacent section levels. The surface was approximated by triangulation and calculated from the surface triangles. Visualization was achieved by introducing the data into commercially available software using z-buffering and Gouraud shading. The geometric precision of the reembedding technique was found to be 0.8-1.5% of the screen width; recovering experiments showed a good approximation to the actual physical volume of unresorbed implants (+/- 2.6%). The error of volume determination due to the limited resolution in the z direction was calculated to be acceptable (< 5.0%) in isotropic objects where the ratio between the radius of the surface curvature and the distance between the sections is > 4. Results indicate that large devices of PDAs are degraded in vivo in a fashion similar to that previously described for in vitro degradation of PLA molded screws by a surface/center differentiation with formation of hollow residuals after 17 weeks and complete degradation with phagocytosis of microparticles after 26 weeks.

Animals↗
PubMed1995

Evaluation of poly(DTH carbonate), a tyrosine-derived degradable polymer, for orthopedic applications.

The polymerization of desaminotyrosinetyrosylhexyl ester (DTH) with phosgene gives rise to poly(DTH carbonate), a new pseudopoly(amino acid). To evaluate the performance of this bioabsorbable material in orthopedic applications, the tissue responses elicited by compression-molded pins of poly(DTH carbonate) and clinically used polydioxanone pins (PDS; Orthosorb) were compared. The two types of pins were implanted in the paravertebral muscle and in the metaphyseal proximal tibia and distal femur of 10 White New Zealand Rabbits for 1, 2, 4, and 26 weeks. The tissue response was evaluated using histologic staining of soft- and hard-tissue sections, fluorescent bone marker of incorporation, and backscattered electron imaging. In soft tissue, both poly(DTH carbonate) and PDS elicited a mild inflammatory response resulting in encapsulation. During the disintegration phase, the PDS implants triggered a foreign body response involving the phagocytosis of polymeric debris by histiocytes and giant cells. No such response was observed for poly(DTH carbonate). In hard tissue, close bone apposition was observed throughout the 26-week test period for poly(DTH carbonate) implants. At the 26-week time point, the poly(DTH carbonate) implants exhibited surface erosion and were penetrated by new bone. In contrast, an intervening fibrous tissue layer was always present between the PDS pins and the bone. At 26 weeks, the PDS implants had partially resorbed and a foreign body response characterized by infiltration in several of the implantation sites. This study indicates that poly(DTH carbonate) and PDS exhibit fundamentally different interactions with hard tissue, and that poly(DTH carbonate) is a promising orthopedic implant material.

Absorption↗