Update on bioresorbable plates in maxillofacial surgery

Bioresorbable Implants in Reduction of Paediatric Zygomaticomaxillary Complex Fractures Concurrent With Internal Orbital Reconstruction

PURPOSE

To evaluate the clinical effectiveness and safety of bioresorbable implants for treating paediatric zygomaticomaxillary complex (ZMC) fractures with concomitant orbital floor defects.

METHODS

A retrospective review of paediatric patients who underwent ZMC repair with concomitant orbital floor fractures with bioresorbable implants in Shanghai Ninth People's Hospital from July 2015 to June 2019 was performed. The primary outcome measures included ocular motility, diplopia, enophthalmos, facial deformities, and restricted mouth opening, as well as complication rates. Pre- and post-operative computed tomography scans were obtained for clinical diagnosis and surgical effectiveness.

RESULTS

Twenty two children were included in this study. Facial deformities were corrected in all 22 cases by surgical reconstruction postoperatively, and the average relative distance of Portals point-Zygomaxillare and Anteriornasalspine-Zygomaxillare were 1.3 ± 0.6mm ( P = 0.22) and 1.2 ± 0.5mm ( P = 0.19). The eye movement restored to normal in 13 patients. The mean amount of relative enophthalmos was 1.0 ± 0.4 mm ( P = 0.12). 12 cases had complete resolution of diplopia postoperatively at the extremes of the gaze, and 1 case presented persistent diplopia on the down gaze as before, but from level III to level I. Facial numbness was resolved completely in 6 cases, and 2 cases presented with persistent numbness but relieved significantly. The average Hounsfield units of RapidSorb plates and OrbFloor PI were 154 ± 5 and 99 ± 4 respectively on computed tomography image obtained 1 week postoperatively, which showed no obvious difference compared with 0.5 year postoperatively ( P > 0.1). Hounsfield units of implants gradually declined around 1 year postoperatively. Hounsfield units of RapidSorb plates (20 ± 1) were consistent with periorbital tissue during postoperative 2-year follow-up, and Hounsfield units of OrbFloor PI (19 ± 1) were consistent with periorbital tissue during postoperative 1.5-year follow-up. No patients had severe sequelae or implant related complications postoperatively. None of bone nonunion, malunion, infection or rejection occurred during the follow-up periods.

CONCLUSIONS

Open reduction and internal fixation for the treatment of ZMC fracture have achieved significant improvement in functional and cosmetic outcomes postoperatively. Bioresorbable materials have been proved to be effective and safe in the treatment of children's ZMC and orbital wall fractures.

Restoration of Ramus Height in Child Patients With Extracapsular Condylar Fractures: Is This Mission Almost Impossible to Accomplish?

OBJECTIVE

This study aimed to assess whether ramus height is restored in children with extracapsular condylar fractures treated by conservative or surgery procedures.

METHODS

The sample consisted of 35 children (collected consecutively) less than 12 years old who presented with extracapsular condylar fractures and treated within an 8-year period (June 2011 to April 2019). Data on the age, gender, date of injury, mechanism of trauma, location and pattern of mandibular condylar fracture, associated injuries and treatment methods were recorded and analyzed. Ramus height restoration is the main evaluation indicator during the follow-up period.

RESULTS

Within the 8-year record retrieval, the 35 children sustained 41 extracapsular condylar fractures. For the sample size, 10 (24.4%) and 31 (75.6%) had condylar neck and base fractures, respectively. Deviation and green-stick fracture were the predominant types in condylar neck and base fractures, accounting for more than 3 quarters (31, 75.6%). The majority (33, 80.5%) of patients were treated with nonsurgical treatment, and 8 (19.5%) were treated by open reduction and internal fixation (ORIF). During the follow-up period (1-1419 days, average time of 110.6 days), only 1 patient (with bilateral extracapsular condylar fractures) had their ramus height restored (follow-up period, 256 days). Most members of the ORIF group (5 of 8, 62.5%) postoperatively showed bended ramus (deviated angularly/fragment angulation).

CONCLUSION

Conservative treatment could hardly restore the ramus height of children with extracapsular condylar fractures. Anatomically or totally restoring the ramus height is difficult even with the surgical treatment of ORIF; however, surgical treatment of ORIF can substantially restore the ramus height for dislocated fractures or seriously displaced fractures.

Efficacy of bioresorbable plates in the osteosynthesis of linear mandibular fractures

Background and Objectives:

There are limited evidences available about the performance of biodegradable system in the treatment of linear mandibular fractures without the aid of postoperative maxillomandibular fixation (MMF). Hence, the present study was planned to evaluate the treatment outcomes in mandibular fractures, using 2.5 mm bioresorbable plates and screws without postoperative MMF.

Methodology:

This cohort study compares both prospective and retrospective data. The prospective study treated 20 adult patients with linear mandibular fracture using bioresorbable plates and screws, without using postoperative MMF (Group 1). Retrospective data were collected from a previous published study in which patients were treated with bioresorbable plates and screws with 2 weeks postoperative MMF (Group 2) and those treated with metal plates and screws without postoperative MMF (Group 3). Group 1 patients were followed up at 2 and 4 months to evaluate the functional outcomes in terms of fracture mobility, malocclusion, pain, and soft-tissue deformity and compared with its preoperative findings. Further, the treatment outcomes of Group 1, Group 2, and Group 3 were compared among themselves at 2-month follow-up.

Results:

Group 1 patients showed a significant improvement in the treatment outcomes at 2 and 4-month follow-up. In addition, when 2 months postoperative outcomes were compared among the three groups, no statistically significant difference was observed in the treatment outcomes.

Conclusion:

Endpoint osteosynthesis can be achieved with the bioresorbable fixation system when used in the treatment of un-displaced linear mandibular fractures, without postoperative MMF. A minor modification of using a lower size osteotomy drill can prevent screw loosening.

Efficacy of Altered Two-Point Fixation in Zygomaticomaxillary Complex Fracture

PURPOSE

To reconstruct a zygomaticomaxillary complex (ZMC) fracture, zygomaticofrontal (ZF) suture is the most reliable site to assess anatomical alignment and to secure rigidity. It has been chosen primary site to be fixed, but approach through the lateral eyebrow incision may leave a visible scar. This study suggests altered two-point fixation of ZMC fracture without accessing the ZF suture.

METHODS

In the retrospective study, a total of 40 patients with ZMC fracture were divided into two groups (group 1, two-point fixation and group 2, three-point fixation). Patient demographics and follow-up were evaluated, and degree of reduction including cortical gaps of ZF and inferior orbital (IO) area, protruding difference of zygoma, and malar difference using asymmetry index were measured through preoperative and postoperative CT.

RESULTS

Preoperatively, the means of ZF displacement, IO displacement, protruding difference of zygoma, and facial asymmetry index between the groups were not statistically different. The result was the same after the operation. However, all variables were significantly different before and after surgery within each group. Moreover, mean operation time was significantly different between groups (P value = 0.026).

CONCLUSION

Altered two-point fixation in ZMC fracture excluding incision approaching the ZF provides surgical efficacy and similar surgical outcomes to three-point fixation but offers reduced operation time and fewer complications.

Open Reduction Effects of Digitally Treating Zygomaticomaxillary Complex Fractures With Bio-Resorbable Materials

PURPOSE

The application of bio-resorbable plates in craniomaxillofacial surgery is increasing because of the advantage of avoiding secondary surgery. This study aimed to evaluate the effects of osteosynthesis with prebent bio-resorbable plates for treating zygomaticomaxillary complex (ZMC) fractures.

MATERIALS AND METHODS

We implemented a prospective case series composed of patients with ZMC fractures who underwent treatment at the School of Stomatology at China Medical University. Bio-resorbable plates were used for fracture fixation. The fractures were stabilized with bio-resorbable plates prebent on a 3-dimensionally printed skull model with the fractures reduced using virtual simulation. The primary outcome variable was the stability rate of reduced bone segments. Other study variables were mouth opening, occlusion, paresthesia or anesthesia in the infraorbital nerve region (PAIN), and diplopia. Outcome variables were determined by calculating stability rates of reduced bone segments, resolution rates of postoperative restricted mouth opening, malocclusion, PAIN, and diplopia.

RESULTS

The sample was composed of 11 patients recruited between November 2016 and September 2018. All surgical procedures were successful, with no severe complications. The stability rate of reduced bone segments from different mechanical buttress regions was 100%. Satisfactory postoperative stability of bio-resorbable plates was obtained in all cases. The resolution rates of postoperative restricted mouth opening and malocclusion were 75 and 100%, respectively. PAIN and diplopia symptoms resolved in 50 and 100% of cases, respectively.

CONCLUSIONS

The results suggest that osteosynthesis with bio-resorbable plates prebent on a 3-dimensionally printed skull model, designed by virtual simulation, works well for patients with ZMC fractures. Future studies should focus on the broader applications of these findings in the practice of oral and maxillofacial surgery.

Overview of innovative advances in bioresorbable plate systems for oral and maxillofacial surgery

Maxillofacial osteosynthetic surgeries require stable fixation for uneventful boney healing and optimal remodeling. Although conventional titanium plates and screws for osteofixation are considered the gold standard for rigid fixation in maxillofacial surgeries, bioresorbable implants of plates and screw systems are commonly used for various maxillofacial osteosynthetic surgeries such as orthognathic surgery, maxillofacial fractures, and reconstructive surgery. Titanium plates are limited by their palpability, mutagenic effects, and interference with imaging, which may lead to the need for subsequent removal; the use of a biologically resorbable osteofixation system could potentially address these limitations. However, several problems remain including fundamental issues involving decreased mechanical strength and stability, slow biodegradation, complex procedures, and the available bioresorbable implant materials. Major advances in bioresorbable plate systems have been made with the use of bioactive/resorbable osteoconductive materials and an accelerator of bioresorption, such as polyglycolic acid. This report presents an overview of currently available resorbable implant materials and their applications, with a focus on recent innovative advances and new developments in this field.

The Clinical Feasibility of Newly Developed Thin Flat-Type Bioresorbable Osteosynthesis Devices for the Internal Fixation of Zygomatic Fractures: Is There a Difference in Healing Between Bioresorbable Materials and Titanium Osteosynthesis?

INTRODUCTION

In recent years, bioresorbable plates have undergone remarkable development. However, there has been no attendant improvement in their strength, because strength requires thickness, and complications such as palpability are related to the thickness of bioresorbable plate systems. In this clinical study, we compared the surgical management of zygomatic fractures using newly developed thinner bioresorbable materials or conventional titanium miniplates.

METHODS

Twelve patients with zygomatic fractures were randomly divided equally into 2 groups (6 with new bioresorbable osteosynthesis materials and 6 with standard titanium miniplates). Using computed tomography, we evaluated the thickness of the soft tissue and plate at the zygomaticofrontal sutures in each patient with the help of detailed radiographic computed tomography data at 6 months postoperatively. We compared the amount of soft-tissue volume increase between the uninjured healthy and injured operated sides in each patient.

RESULTS

Both groups eventually achieved satisfactory healing, with a favorable restoration of form and function and without any complications, including palpability. The amount of soft-tissue volume increase at the operated side relative to the uninjured healthy side using new thin bioresorbable plates was 131.1% (range: 101.5-165.8). On the other hand, that of titanium miniplates was 126.4% (range: 102.2-167.6). There was no statistically significant difference (P > 0.05).

CONCLUSION

This newly developed thinner flat-type bioresorbable plate system could be considered clinically useful in the treatment of zygomatic fractures even in easily palpated areas, such as the infraorbital rim or zygomaticofrontal sutures, without any healing differences in skeleton as compared with conventional titanium miniplates.

Effect of Injection Molding Melt Temperatures on PLGA Craniofacial Plate Properties during In Vitro Degradation

The purpose of this article is to present mechanical and physicochemical properties during in vitro degradation of PLGA material as craniofacial plates based on different values of injection molded temperatures. Injection molded plates were submitted to in vitro degradation in a thermostat bath at 37 ± 1°C by 16 weeks. The material was removed after 15, 30, 60, and 120 days; then bending stiffness, crystallinity, molecular weights, and viscoelasticity were studied. A significant decrease of molecular weight and mechanical properties over time and a difference in FT-IR after 60 days showed faster degradation of the material in the geometry studied. DSC analysis confirmed that the crystallization occurred, especially in higher melt temperature condition. DMA analysis suggests a greater contribution of the viscous component of higher temperature than lower temperature in thermomechanical behavior. The results suggest that physical-mechanical properties of PLGA plates among degradation differ per injection molding temperatures.

Effect of Injection Molding Melt Temperatures on PLGA Craniofacial Plate Properties during In Vitro Degradation

The purpose of this article is to present mechanical and physicochemical properties during in vitro degradation of PLGA material as craniofacial plates based on different values of injection molded temperatures. Injection molded plates were submitted to in vitro degradation in a thermostat bath at 37 ± 1°C by 16 weeks. The material was removed after 15, 30, 60, and 120 days; then bending stiffness, crystallinity, molecular weights, and viscoelasticity were studied. A significant decrease of molecular weight and mechanical properties over time and a difference in FT-IR after 60 days showed faster degradation of the material in the geometry studied. DSC analysis confirmed that the crystallization occurred, especially in higher melt temperature condition. DMA analysis suggests a greater contribution of the viscous component of higher temperature than lower temperature in thermomechanical behavior. The results suggest that physical-mechanical properties of PLGA plates among degradation differ per injection molding temperatures.

Surgical treatment of isolated zygomatic fracture: Outcome comparison between titanium plate and bioabsorbable plate

BACKGROUND

Zygoma fracture is of clinical importance because malar prominence plays an essential role in facial appearance. Traditionally, most maxillofacial surgeons perform osteosynthesis with titanium plates and screws for rigid fixation. However, this procedure has certain disadvantages that include the possibility of implant exposure, palpability or loosening of the screws, painful irritation, temperature sensitization, and radiographic artifacts. In this study, we compared the function and satisfaction outcome between Bonamates^® bioabsorbable implant and Leibinger titanium implant.

METHOD

Consecutively 53 patients with isolated unilateral zygomatic fracture that were treated with the Bonamates^® bioabsorbable plate system, n = 53 were compared to patients with the titanium plate system, n = 55 in the period between 2009 and 2013. All patients were followed-up at least 6 months. Preoperative and postoperative facial computed tomography (CT) scans were performed and scored from 0 to 2 in the 5 areas of zygoma. A score of 2 indicated the most severely displaced fracture in one of the areas. A visual analogue scale ranging from 0 to 10 was used to assess the postoperative aesthetic and functional satisfactions.

RESULT

The mean ages of the patients in the bioabsorbable and titanium plate groups were 33 years and 30 years, respectively. The male to female ratios were 1.2:1 (bioabsorbable plate group) and 1.1:1 (titanium plate group). The average preoperative CT scan scores of the bioabsorbable and titanium plate groups were 5.7 and 5.1, respectively. The postoperative CT scan scores of the bioabsorbable and titanium plate groups were 1.3 and 1.1, respectively. The implant cost of the bioabsorbable group was approximately 6-fold higher than that of the titanium plate group. The complication rate was similar in both groups and included complications such as palpable implant, skin irritation, and hypersensitive cheek. The patients in both groups attained similar mouth-opening function and a satisfactory score at 6 months after operation.

CONCLUSION

This study revealed that the bioabsorbable plate outcome was similar to the titanium plate outcome for patients with isolated unilateral zygomatic fracture. The bioabsorbable implant system provides another option for internal fixation devices in the treatment of zygomatic fractures and avoids implant removal surgery; however, the implant cost of bioabsorbable plates is higher than that of titanium plates in Taiwan.

Volume correction in the aging hand: role of dermal fillers

The hands, just like the face, are highly visible parts of the body. They age at a similar rate and demonstrate comparable changes with time, sun damage, and smoking. Loss of volume in the hands exposes underlying tendons, veins, and bony prominences. Rejuvenation of the hands with dermal fillers is a procedure with high patient satisfaction and relatively low risk for complications. This study will review relevant anatomy, injection technique, clinical safety, and efficacy of dermal filler volumization of the aging hand.

Bioabsorbable osteofixation for orthognathic surgery

Orthognathic surgery requires stable fixation for uneventful healing of osteotomized bony segments and optimal remodeling. Titanium plates and screws have been accepted as the gold standard for rigid fixation in orthognathic surgery. Although titanium osteofixation is the most widely used approach, the use of bioabsorbable devices has been increasing recently. Biodegradation of bioabsorbable devices eliminates the need for a second operation to remove metal plates and screws. However, long-term stability and relapse frequency in bioabsorbable osteofixation are still insufficiently studied, especially in cases of segmental movements of great magnitude or segmental movements to a position where bony resistance exists. This paper reviews the background, techniques, and complications of bioabsorbable osteofixation and compares bioabsorbable and titanium osteofixation in orthognathic surgery in terms of skeletal stability.

To evaluate the efficacy of biodegradable plating system for fixation of maxillofacial fractures: A prospective study

Aims:

The present study was undertaken to evaluate the efficacy of biodegradable plating system for fixation of maxillofacial fractures and to study the morbidity associated with the use of biodegradable plates and screws.

Materials and Methods:

This prospective study consisted of 10 patients with maxillofacial fractures requiring open reduction and internal fixation. Fractures with infection, comminuted and pathological fractures were excluded. All were plated with biodegradable system (Inion CPS) using standard plating principles and observed for a total period of 24 weeks. Characteristics of the fractures, ease of use of bioresorbable plate/screw system and post operative complications were assessed.

Results:

Of total 10 patients, eight patients were of midface fracture and two pediatric patients with mandibular fracture, with nine male and one female. The mean age was 32.8 years. Out of 20 plates and 68 screws applied to the 10 fractures sites; there were three incidences of screw breakage with no other intraoperative difficulties. Paresthesia of the infraorbital nerve was present in two patients, and recovered completely in four weeks after surgery. Fracture reduction was considered to be satisfactory in all cases. One patient developed postsurgical infection and was managed with oral antibiotics and analgesics.

Conclusions:

Favorable healing can be observed through the use of biodegradable plates and screws to stabilize selected midface fractures in patients of all ages, as well as mandible fractures in early childhood, however further studies with more sample size are required.

Bioabsorbable fixation devices in trauma and bone surgery: current clinical standing

Bioabsorbable fixation devices are increasingly used in trauma, orthopedic and craniomaxillofacial surgery. The devices are essentially made of polylactic acid and/or polyglycolic acid polymers. Ultra-high-strength implants are manufactured from such polymers using self-reinforcing techniques. Implants are available for stabilization of fractures, osteotomies, bone grafts and fusions, as well as for reattachment of ligaments, tendons, meniscal tears and other soft tissue structures. As these implants are completely absorbed, the need for a removal operation is overcome and long-term interference with tendons, nerves and the growing skeleton is avoided. The risk of implant-associated stress shielding, peri-implant osteoporosis and infections is reduced. Implants do not interfere with clinical imaging. Current clinical use of bioabsorbable devices is reviewed.

Effect of in vitro aging on the stiffness of bioabsorbable fixation plates

The purpose of this study was to investigate the effect of in vitro aging on the stiffness of bioabsorbable fixation plates. Twenty-four polylactic/polyglycolic acid plates (LactoSorb; Lorenz, Jacksonville, FL) were divided in 3 groups of 8 specimens each. Group A served as control, and groups B and C were immersed in 0.1 M lactic acid for 15 and 30 days, respectively. All specimens were subjected to a 3-point bending test, using a universal testing machine, and the stiffness of each specimen was estimated. When analyzed with one-way analysis of variance, no difference was observed for the control and in vitro-aged specimens with regard to stiffness. Long-term (30 d) in vitro aging of poly-L-lactic acid bioabsorbable fixation plates does not seem to significantly affect the stiffness of the material as derived from a 3-point bending test.

Influence of nanofibers on growth and gene expression of human tendon derived fibroblast

Background

Rotator cuff tears are a common and frequent lesion especially in older patients. The mechanisms of tendon repair are not fully understood. Common therapy options for tendon repair include mini-open or arthroscopic surgery. The use of growth factors in experimental studies is mentioned in the literature. Nanofiber scaffolds, which provide several criteria for the healing process, might be a suitable therapy option for operative treatment. The aim of this study was to explore the effects of nanofiber scaffolds on human tendon derived fibroblasts (TDF's), as well as the gene expression and matrix deposition of these fibroblasts.

Methods

Nanofibers composed of PLLA and PLLA/Col-I were seeded with human tendon derived fibroblasts and cultivated over a period of 22 days under growth-inductive conditions, and analyzed during the course of culture, with respect to gene expression of different extra cellular matrix components such as collagens, bigylcan and decorin. Furthermore, we measured cell densities and proliferation by using fluorescene microscopy.

Results

PLLA nanofibers possessed a growth inhibitory effect on TDF's. Furthermore, no meaningful influence on the gene expression of collagen I, collagen III and decorin could be observed, while the expression of collagen X increased during the course of cultivation. On the other hand, PLLA/Col-I blend nanofibers had no negative influence on the growth of TDF's. Furthermore, blending PLLA nanofibers with collagen had a positive effect on the gene expression of collagen I, III, X and decorin. Here, gene expression indicated that focal adherence kinases might be involved.

Conclusion

This study indicates that the use of nanofibers influence expression of genes associated with the extra cellular matrix formation. The composition of the nanofibers plays a critical role. While PLLA/Col-I blend nanofibers enhance the collagen I and III formation, their expression on PLLA nanofibers was more comparable to controls. However, irrespective of the chemical composition of the fibres, the collagen deposition was altered, an effect which might be associated with a decreased expression of biglycanes.

A retrospective follow-up of ankle fracture patients treated with a biodegradable plate and screws

BACKGROUND

Biodegradable fixation implants have been developed to avoid secondary hardware removal. The aim of this study was to retrospectively follow-up ankle fracture patients treated with a biodegradable plate and screws, and to evaluate the clinical outcome and occurrence of complications.

METHODS

Fifty-seven ankle fracture patients treated with biodegradable implants were invited, and a total of 50 were available to participate in this study. The follow-up included a review of each patient's medical records, evaluation of radiographs, fracture reduction classification, and functional scoring.

RESULTS

There were 36 lateral malleolar and 14 bimalleolar fractures. No perioperative complications occurred. Average follow-up time was 17 months. All fractures healed. Fracture alignment was classified as anatomical in 49 patients and good in 1 case. The mean Olerud and Molander functional ankle score at final follow-up was 86. Eight patients had postoperative complications. These included delayed wound healing in 1 case, 3 cases of deep-vein thrombosis, and 4 soft tissue reactions.

CONCLUSIONS

According to the results of this retrospective study, the biodegradable implants used yielded fracture healing and functional results comparable to those previously reported after conventional metal fixation.

Temporal miniplates in the frontozygomatic area--an anatomical study

PURPOSE

The advantages of rigid fixation over wire osteosynthesis are well established for the management of facial trauma. Miniplates in the frontozygomatic area are traditionally applied to the lateral face of the orbital rim, but with some undesirable effects, such as palpability, visibility, and risk of penetration into the anterior cranial fossa. The aim of this study was to perform an anatomical study to validate the use of miniplates on the temporal face of the frontozygomatic region.

METHODS

Osseous thickness measurements were performed in 30 skulls, on four points above and four below the suture, at 3-mm intervals, perpendicular to the bone surface.

RESULTS

There is enough bone thickness to apply the screws, ranging between 4 and 6.5 mm. The first hole over the frontozygomatic suture should receive the smallest screws and the other areas can receive screws up to 6 mm. All drillings are made from the temporal fossa to the orbit, and its contents should therefore be protected during the perforations. At the measured points there is no risk of anterior cranial fossa penetration.

CONCLUSION

This study suggests that it is possible to use miniplates at the temporal aspect of the frontozygomatic suture.

Biomechanical in vitro evaluation of the effect of cyclic loading on the postoperative fixation stability and degradation of a biodegradable ankle plate

The effect of cyclic loading on the postoperative fixation stability of a biodegradable ankle plate was tested biomechanically during 12 weeks of hydrolytic degradation. Fracture of the lateral malleolus was simulated, and the parameters of cyclic loading were chosen to represent the physiological conditions during the healing period. Additionally, the effect of cyclic loading on degradation was investigated by measuring the inherent viscosities. In Group I, the cyclic loading was conducted in four phases with gradual increases in estimated walking distance and speed during the healing period. In Group II, cyclic loading was conducted after 12 weeks. Group III was used as a control for inherent viscosity measurements. None of the specimens failed under cyclic loading. No significant differences were found between the loaded groups in any of the parameters measured. Additionally, no significant difference was found in inherent viscosities at 12 weeks. The initial fixation stability provided by the biodegradable ankle plate remains biomechanically unchanged over 12 weeks. Cyclic loading, applied either during or after 12 weeks of hydrolytic degradation, does not seem to have any clinically relevant effect on the fixation stability or the degradation properties.

Blow-out fractures in children: six years’ experience

OBJECTIVES

To present and analyze our experience in treating blow-out fractures in children, over a 6-year period.

STUDY DESIGN

The study was retrospective with 16 consecutive cases of blow-out fractures in children aged 5 to 15 years. All patients presented with impairment of eye motility and diplopia together with radiological findings. Treatment included fracture reduction, release of entrapped periorbital soft tissues, and placement of an alloplastic membrane on the orbital floor. Fractures were linear in 11 cases (trapdoor) and severe or comminuted in 5 cases.

RESULTS

Clinical symptoms subsided in all cases. Complete recovery of eye motility was achieved after surgical procedure in 13 cases; 2 patients presented late but had full recovery, and 1 patient, 4 years postoperatively, still had slight motility impairment.

CONCLUSIONS

Surgical treatment of blow-out fractures, including periorbital tissue release and placement of a membrane lining on the orbital floor, presented satisfactory results in our cases.

Orthodontics in 3 millennia. Chapter 14: surgical adjuncts to orthodontics

Around 1970, after overcoming obstacles related to anesthesia, infection, and blood supply, orthognathic surgeons come into their own. The history of cleft lip and palate treatment has a much earlier beginning because a deformed infant evokes a strong desire to intervene. Angle's belief that orthodontists can grow bone finally came to fruition with the advent of distraction osteogenesis, which developed from the limb-lengthening procedures of Ilizaroff in Russia. Now distraction osteogenesis has replaced osteotomies in many applications.

A citric acid-based hydroxyapatite composite for orthopedic implants

We describe a novel approach to process bioceramic microparticles and poly(diol citrates) into bioceramic-elastomer composites for potential use in orthopedic surgery. The composite consists of the biodegradable elastomer poly(1,8-octanediol-citrate) (POC) and the bioceramic hydroxyapatite (HA). The objective of this work was to characterize POC-HA composites and assess the feasibility of fabricating tissue fixation devices using machining and molding techniques. The mechanical properties of POC-HA composites with HA (40, 50, 60, 65wt.%) were within the range of values reported for tissue fixation devices (for POC-HA 65wt.%, S(b)=41.4+/-3.1, E(b)=501.7+/-40.3, S(c)=74.6+/-9.0, E(c)=448.8+/-27.0, S(t)=9.7+/-2.3, E(t)=334.8+/-73.5, S(s)=27.7+/-2.4, T(s)=27.3+/-4.9, all values in MPa). At 20 weeks, the weight loss of POC-HA composites ranged between 8 and 12wt.%, with 65wt.% HA composites degrading the slowest. Exposure of POC-HA to simulated body fluid resulted in extensive mineralization in the form of calcium phosphate with Ca/P of 1.5-1.7 similar to bone. POC-HA supported osteoblast adhesion in vitro and histology results from POC-HA samples that were implanted in rabbit knees for 6 weeks suggest that the composite is biocompatible. Synthesis of POC-HA is easy and inexpensive, does not involve harsh solvents or initiators, and the mechanical properties of POC-HA with 65wt.% HA are suitable for the fabrication of potentially osteoconductive bone screws.

Complications after zygoma fracture fixation: Is there a difference between biodegradable materials and how do they compare with titanium osteosynthesis?

OBJECTIVE

Biodegradable materials are particularly useful for the fixation of zygomatic fractures. Different systems are commercially available. The aim of this study was to compare the clinical outcome of zygomatic fracture fixation using 3 biodegradable systems and a titanium osteosynthesis system.

STUDY DESIGN

Patients with displaced fractures of the zygomatic bone presenting at our department from October 2001 to May 2003 were randomly allocated to 1 of 3 treatment groups for fracture fixation (study group A: LactoSorb: n = 18; study group B: BioSorb: n = 18; study group C: Delta: n = 18). Treatment outcome and complication rates were compared with a historic patient group with zygomatic fractures fixed with titanium osteosynthesis (control group D: n = 15).

RESULTS

A total of 64 patients (study groups A + B + C: n = 49; control group D: n = 15) were followed for at least 24 months (range: 24 to 44 months). Forty-nine patients in the biodegradable study groups (group A: n = 15; group B: n = 17; group C: n = 17) who had their fractures fixed with biodegradable plates and screws alone or in combination with titanium plates and screws were reviewed postoperatively. Uneventful healing occurred during the entire follow-up period in 39 (80%) out of 49 patients in the biodegradable groups (A + B + C) and in 12 (80%) out of 15 patients in group D. Ten patients in groups A + B + C developed postoperative complications (infection: n = 3; soft tissue dehiscence: n = 2; implant-related tissue reactions: n = 5), compared with 3 patients in group D (soft tissue dehiscence: n = 1; unspecific pain: n = 2) (P = .97). Complications occurred in 4 patients in group A and 3 patients each in groups B and C. Smokers developed significantly more postoperative complications than nonsmokers in groups A + B + C (P = .01).

CONCLUSION

There was no significant difference between biodegradable osteosynthesis materials or between biodegradable materials and titanium fixation with respect to fracture healing and postoperative complications. Postoperative complications were of a minor nature and resolved spontaneously or after local therapy. Smoking habits may play a significant role in the incidence of complications with biodegradable materials.

Biodegradable fixation of mandibular fractures in children: stability and early results

OBJECTIVE

The aim of this study was to assess the safety and efficiency of biodegradable self-reinforced (SR-PLDLA) bone plates and screws in open reduction and internal fixation of mandible fractures in children.

STUDY DESIGN

Thirteen patients (5 female, 8 male; mean age 12 years, range 5-16 years) were operated on various fractures of the mandible (2 symphyseal, 6 parasymphyseal, 4 body, 3 angle, 1 ramus, 2 condylar fractures). The mean follow-up time was 26.4 months (range 10.9-43.4 months). Intermaxillary fixation was applied in cases with concomitant condylar fractures up to 3 weeks.

RESULTS

Primary healing of the fractured mandible was observed in all patients. Postoperative complications were minor and transient. The outcome of the operations was not endangered. Adverse tissue reactions to the implants, malocclusion, and growth restrictions did not occur during the observation period.

CONCLUSIONS

Pediatric patients benefit from the advantages of resorbable materials, especially from faster mobilization and the avoidance of secondary removal operations. Based on these preliminary results, self-reinforced fixation devices are safe and efficient in the treatment of pediatric mandible fractures. However, further clinical investigations are necessary to evaluate the long-term reliability.

An evaluation of the clinical application of three different biodegradable osteosynthesis materials for the fixation of zygomatic fractures

OBJECTIVE

The aim of this prospective study was to compare the clinical handling of 3 different biodegradable osteosynthesis materials and to determine whether they can be used for the fixation of all types of zygomatic fractures.

STUDY DESIGN

A total of 54 consecutive patients who presented with displaced fractures of the zygomatic bone between October 2001 and May 2003 were randomly allocated to 3 biodegradable material groups for the fixation of the fractures. A titanium fixation system was used as rescue osteosynthesis whenever biodegradable materials failed.

RESULTS

Seventy-one (75.5%) of 94 fracture sites were fixed with biodegradable osteosynthesis; 23 (24.5%) had to be fixed with titanium plates and screws. No statistically significant difference was found between the 3 biodegradable materials with regard to their suitability for zygomatic fracture fixation (P = .16). Nonstable fixation (n = 7) or the need to fix small fragments (n = 16) were the reasons for using the titanium fixation system as rescue osteosynthesis at these sites. Biodegradable materials were most frequently unfeasible for use at the infraorbital rim and in the zygomaticomaxillary/anterior sinus wall area.

CONCLUSIONS

It was possible to stabilize 3 of 4 zygomatic fractures with 1.5- or 1.7-mm biodegradable osteosynthesis. Insufficient fracture stabilization, especially at the infraorbital rim and the zygomaticomaxillary crest/anterior sinus wall, was the main reason to switch to titanium osteosynthesis. The biodegradable screw design is possibly too bulky for these particular bony structures.

Self-reinforced biodegradable plates and screws for fixation of zygomatic fractures

PURPOSE

The aim of this retrospective clinical study was to evaluate zygomatic fracture fixation with the BioSorbFX osteosynthesis system by assessing stability of reduction as well as complications in the first postoperative year and by conducting a survey to document surgeons' opinions on biodegradable osteosynthesis for this indication.

MATERIAL

From January to September 2003, 25 patients with displaced non-infected unilateral fracture of the zygoma were operated upon (m:f = 20:5; age 17-81 years; mean 39.4 years) using the BioSorbFX 2.0 and/or 1.5 mm osteosynthesis systems.

METHODS

A: Clinical and radiographic examinations were carried out immediately postoperatively and after 1, 3, 6, 9 and 12 months.

METHODS

B: Surgeons were asked to participate in a survey critically evaluating their experience with biodegradable osteosynthesis systems.

RESULTS

A: All fractures of the zygoma healed uneventfully. An excessive soft tissue reaction due to the degradation process was not seen. Three minor complications which resolved after local therapy occurred in the immediate postoperative phase.

RESULTS

B: In the survey, the handling of biodegradable plates in general was rated worse than metal plate osteosynthesis.

CONCLUSION

Fixation of fractures of the zygoma with the BioSorbFX system was simple and safe. The fixations remained stable and bony healing was uneventful. Postoperative complications were few, of a minor nature and not related to the process of biodegradation.

Use of bioabsorbable osteofixation devices in the hand

Bioabsorbable internal fixation by means of pins, tacks, screws and miniplates offers an alternative to metallic osteofixation for the stabilization of small bone fractures, osteotomies, ligament injuries and fusions in the hand. The advantages of using them include avoidance of metallic-implant-related long-term complications and a secondary removal operation. Currently the most commonly used devices are made of poly L-lactide (PLLA) and copolymers of polylactides (P(L/DL)LA) and polyglycolide (PLGA). In areas of mechanical stress, the use of ultra-high-strength self-reinforced devices is recommended. Biomechanical studies on fresh frozen bones have shown that the fixation rigidity achieved with self-reinforced devices approaches that of metallic osteofixation methods. The reliability of modern implants has been confirmed in several experimental and clinical studies.

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.

Fixation of zygomatic fractures with a biodegradable copolymer osteosynthesis system: short- and long-term results

Biodegradable osteosynthesis devices can be viewed as addition to, not yet replacement for conventional metal osteosynthesis materials. In a series of 65 patients with zygomatic fractures, a short-term complication/sequelae rate of 22.8% and a long-term complication rate of 9.4% were recorded. Lactosorb plates, panels and screws were the only devices used for osteosynthesis. All complications associated with the biodegradable material could be considered minor and were resolved by the use of minor surgical procedures or conservative measures. The results of this study indicate that treatment of zygomatic fractures with biodegradable osteosynthesis material has no major long-term adverse effects beyond the total material resorption time.

Are there any complications with bioabsorbable fixation devices? A 10 year review in orthognathic surgery

Bioabsorbable fixation devices have been used in our departments between November 1991 and November 2001 in orthognathic surgery. The aim of this retrospective study was to assess all complications experienced during this time period, when we have operated 163 patients who have undergone 329 orthognathic osteotomies fixated with bioresorbable devices. No postoperative intermaxillary fixation was used. Light guiding elastics were used for 5 to 7 weeks. Patients' acceptance was generally excellent and very few complications occurred during this follow-up of 10 years. The complications were minor and did not affect the end results of the operations. Minor complications occurred in 14 patients (8.6%). Only one patient (0.6%) had a postoperative infection with elevated infection parameters. The other minor complications consisted mainly of dehiscence of the wound and plate exposure together with granulation tissue in the operation field. The rest of the complications occurred in the beginning of our study, when large screw heads on top of the bone irritated the patient and had to be removed. Insufficient fixation resulted in open bite in three patients (1.8%) in the beginning of the trial use of new devices, which no longer are used. Based on our experience, bioresorbable devices are safe to be used in orthognathic procedures. However, there is a learning curve, as there is with all new methods introduced.

New method of pediatric cranioplasty for skull defect utilizing polylactic acid absorbable plates and carbonated apatite bone cement

Cranial defect repair in the pediatric population requires a variety of special considerations. The pediatric skull has a dynamic nature that prohibits the use of rigid fixation, which is commonly applied in the adult population. A technique using a combination of polylactic acid plates and carbonated apatite bone cement has been devised by our group. Skull defects of varying sizes were repaired in 34 pediatric patients. Patients were examined on postoperative day 3 and at 3 months via three-dimensional computed tomography scans. Patients have been followed up to 60 months after surgery without complications or failures to date. This method benefits the pediatric patients undergoing cranioplasty by minimizing the insertion of long-term foreign bodies and allows the possibility for transformation of this construct into viable tissue.

Successful Use of Biosorb Osteofixation Devices in 165 Cranial and Maxillofacial Cases: A Multicenter Report

Bioabsorbable osteofixation devices were developed to avoid problems associated with metals. Bioabsorbable devices are mostly made of the polymers polylactide, polyglycolide, and their copolymers [polyglycolide-co-polylactide and P(L/DL)LA]. Using the technique of self-reinforcement of bioabsorbable materials, it is possible to manufacture osteofixation devices with ultra high strength. Self-reinforced polyglycolide-co-polylactide 80/20 was selected to make devices (Biosorb PDX) for this study because of its favorable degradation characteristics. The aim of this study was to evaluate the efficacy of using self-reinforced polyglycolide-co-polylactide 80/20 (Biosorb) plates and screws in the fixation of osteotomies in craniomaxillofacial surgery. In a prospective study, 165 patients (161 children and 4 adults) were operated on in four European Union centers (Paris, Innsbruck, London, and Oulu) from May 1, 1998 to January 31, 2002. Indications included correction of dyssynostotic deformities (n = 159), reconstruction of bone defects after trauma (n = 2), tumor removal (n= 2), and treatment of encephalocele (n = 2). Plates used were 0.8, 1, or 1.2 mm thick, and screws had an outer (thread) diameter of 1.5 or 2 mm and a length of 4, 6, or 8 mm. Tacks had an outer diameter of 1.5 or 2 mm and a length of 4 or 6 mm. During surgery, the devices were easy to handle and apply and provided stable fixation apart from 2 cases. Postoperative complications occurred in 12 cases (7.3%), comprising infection (n = 6), bone resorption (n = 4), diabetes insipidus (n = 1), delayed skin wound healing/skin slough (n = 2), and liquorrhea (n = 1). Accordingly, self-reinforced polyglycolide-co-polylactide 80/20 (Biosorb) plates and screws can be used safely and with a favorable outcome in corrective cranioplasties, especially in infants and young children.

Self-reinforced bioabsorbable miniplates for skeletal fixation in complex hand injury: three case reports

We report our preliminary experience with 3 cases in which internal fixation with a self-reinforced poly-l/dl-lactide 70/30 miniplate and 1.5-mm or 2.0-mm screws were used to stabilize an open metacarpal fracture, a metacarpophalangeal arthrodesis in a thumb replantation, and an interposed bone graft for reconstruction of a thumb. Clinical and radiologic follow-up evaluation lasted for 12 to 20 months. Bone healing was uneventful in all 3 cases with no displacement or delayed union. The implants were biocompatible with no clinically manifested foreign body reaction. Because of the self-reinforcing manufacturing technique the plates have metal-like mechanical and handling properties. Complete late resorption makes self-reinforced poly-l/dl-lactide 70/30 miniplating systems an attractive alternative to metallic implants for skeletal stabilization of small bones of the hand.

Self-reinforced bioresorbable poly-L/DL-Lactide [SR-P(L/DL)LA] 70/30 miniplates and miniscrews are reliable for fixation of anterior mandibular fractures: A pilot study

OBJECTIVE

Bioresorbable osteofixation devices are being increasingly used in orthognathic surgery and in cases of trauma to avoid problems associated with conventional metal osteofixation devices. The aim of this clinical study was to assess the reliability and efficacy of bioresorbable self-reinforced poly-L/DL-lactide (SR-P(L/DL)LA 70/30) plates and screws in the fixation of mandibular fractures in adults.

STUDY DESIGN

Ten patients (20 to 49 years old) with isolated anterior mandibular parasymphyseal fractures were treated by means of open reduction and internal fixation using SR-P(L/DL)LA 70/30 bioresorbable plates and screws.

RESULTS

During the minimum of 6 months of follow-up, no problems were encountered except for 1 case where a plate became exposed intraorally and infected. This required debridement and later excision of the exposed part of the plate. Despite this setback the fractured bone healed well.

CONCLUSIONS

SR-P(L/DL)LA 70/30 plates and screws are reliable for internal fixation of anterior mandibular fractures in adults. Proper soft tissue coverage should be ensured to avoid plate exposure. Should implant exposure occur, it might be necessary to excise the exposed part after fracture healing (6-8 weeks postoperatively).

Absorbable plates for rib fracture repair: preliminary experience

BACKGROUND

Absorbable prostheses are currently used in a variety of bone reconstructions and fixations.

METHODS

This is a case series of rib fracture fixation using absorbable plates and screws consisting of 70:30 poly(L-lactide-co-D,L-lactide) from April 2001 through November 2002.

RESULTS

Ten patients underwent rib fracture fixation with absorbable plates and screws. Indications included flail chest with failure to wean (five patients), acute pain with instability (four patients), and chest wall defect (one patient). All patients with flail chest weaned from mechanical ventilation successfully. All patients with pain and instability reported rapid subjective improvement or resolution. The patient with a chest wall defect repair returned to full athletic activity without limitations at 6 months. Thoracoscopic assistance was used in three cases and muscle-sparing incisions were used in eight cases. Two patients with screw fixation only developed loss of rib fracture reduction. One patient developed a wound infection requiring drainage. The period of follow-up ranged from 3 to 18 months.

CONCLUSION

Absorbable plates produce good clinical results and are an option for rib fracture repair. Two-point fixation (screw fixation plus suture cerclage) is required. Further refinements in technique should focus on minimally invasive methods.

Polylactic acid implants (New-Fill) to correct facial lipoatrophy in HIV-infected patients: results of the open-label study VEGA

BACKGROUND

In the absence of currently available therapy to manage facial lipoatrophy, strategies used to compensate for facial fat loss warrant clinical evaluation.

METHODS

The goal of this open-label, single-arm, pilot study was to evaluate the efficacy and safety of facial injections of poly-L-lactic acid (PLA) (New-Fill) in HIV-infected patients with severe facial lipoatrophy. Patients received four sets of injection at day 0 and then every 2 weeks for 6 weeks. Patients were evaluated by clinical examination, facial ultrasonography, and photography at screening and at weeks 6, 24, 48, 72, and 96.

RESULTS

Fifty patients were enrolled. At entry, the median facial fat thickness was equal to zero (range, 0.0-2.1 mm). The median total cutaneous thickness (TCT) increased significantly from baseline : +5.1 mm (range, 2.2-8.6 mm) at week 6, +6.4 mm (range, 3.1-9.1 mm) at week 24, +7.2 mm (range, 4.2-9.6 mm) at week 48, +7.2 mm (range, 3.5-9.6 mm) at week 72 and +6.8 mm (range, 3.9-10.1 mm) at week 96 (P < 0.001). The proportion of patients with TCT > 10 mm was observed in 19% at week 6, 41% at week 24, 61% at week 48, 52% at week 72 and 43% at week 96. In 22 (44%) patients, palpable but non-visible subcutaneous micronodules were observed with a spontaneous resolution in six patients at week 96.

CONCLUSION

The benefit of PLA for the correction of the facial lipoatrophy in HIV-infected patients was clearly demonstrated, with an evident aesthetic and quality of life improvement. The efficacy, safety profile, and the simplicity of the injection schedule of PLA make this filling material a potentially attractive treatment.

Use of new bioabsorbable tacks and a tackshooter in cranial bone osteofixation saves operative time

A new device (a tackshooter) to apply bioabsorbable tacks in craniofacial surgery has been developed. This new device was used in 15 children who underwent various cranioplasty procedures to demonstrate its reliability and simple technical application in cranial bone osteofixation. Bone segments were fixed together and to the cranial bones using Biosorb plates and tacks. Stable and secure fixation was obtained intraoperatively, with reduced operative time (10-15%) compared with earlier use of plates and screws. However, its use in very thin bone (<1 mm thick) is very limited because of bone fragility. In conclusion, use of tacks and a tackshooter reduces operative time, risk of infection and blood loss, and consequently costs. It is therefore very useful in selected craniofacial cases.

The use of bioabsorbable osteofixation devices in craniomaxillofacial surgery

Because of problems associated with the conventional osteofixation devices used in craniomaxillofacial surgery, bioabsorbable devices have presented an appealing alternative. Devices made of the polymers polyglycolide (PGA) and polylactide (PLA) and their copolymers (PLGA and PLDLA) are currently the most commonly used. Strong implants can be manufactured from these polymers with a self-reinforcing technique and used in the treatment of fractures and osteotomies. Self-reinforced devices have been studied for nearly 2 decades by our multidisciplinary research group for internal fixation of the bone in both experimental and clinical settings. In craniomaxillofacial fractures and osteotomies they have been used for as long as 10 years with no significant clinical problems. Because of more favored degradation characteristics, currently the copolymer devices (PLDLA and PLGA) represent the advancing front in the application of absorbable devices in craniomaxillofacial surgery. By using bioabsorbable devices, several problems associated with conventional biostable devices can be avoided, especially in children. New techniques that are not possible with biostable devices can be developed by using bioabsorbable devices, too. Our experience with and research on self-reinforced devices are shared here.

A new technique for cranial bone osteofixation: use of bioabsorbable tacks and plates to fix parietal bone split grafts used for reconstruction of a posttraumatic frontal bone defect

Recent advances in bioabsorbable devices have introduced tacks that do not require tapping. This may help to reduce operative time and, consequently, costs. The goal of this study was to demonstrate the feasibility of a new method of cranial bone osteofixation using novel bioabsorbable tacks and plates instead of screws. A 36-year-old man presented for elective cranioplasty to reconstruct a large frontal cranial bone defect that followed a decompression operation performed because of a head injury sustained 6 months previously. Cranioplasty was performed using split parietal bone grafts to reconstruct the defect. Bone grafts were fixed together and to the skull using self-reinforced (SR) poly(L/DL)lactide [SR-poly(L/DL)lactide] (70/30) (Biosorb FX) plates (n = 10) and tacks (n = 98). The plates were 0.6 mm thick, 102 mm long, and 12 mm wide. The tacks had a maximum thread diameter of 2 mm and a length of 6 mm. The tacks used did not require any tapping procedure, and they were applied using a special applicator gun. Stable and secure fixation was obtained during surgery. The postoperative period was uneventful, except for delayed epithelialization of a small area (1 x 0.5 cm) over the frontal skin that healed later. One year after surgery, the cosmetic result was excellent, and no complications were detected. Stabilization of large cranial bone pieces can be achieved using bioabsorbable SR-poly(L/DL)lactide plates and tacks, with excellent cosmetic results. The method is thought to be reliable and may help to reduce operative time.

Developments in craniomaxillofacial surgery: use of self-reinforced bioabsorbable osteofixation devices

Because of the problems associated with the conventional osteofixation devices used in craniomaxillofacial surgery, absorbable devices present an appealing alternative. Devices made of the polymers polylactide, polyglycolide, and their copolymers (PLGA and P[L/DL]LA) are currently the most commonly used. Ultrahigh-strength implants can be manufactured from these polymers with the self-reinforcing technique. Over the authors' almost two decades of study, both in experimental and clinical settings, self-reinforced devices have proved to be biocompatible, easy to handle, and mechanically strong, even for the fixation of femoral neck fractures. In craniomaxillofacial surgery, the authors have used self-reinforced devices for over 8 years without complications. Because of the more favored degradation characteristics, currently the copolymeric self-reinforced devices (P[L/DL]LA, Biosorb FX and PLGA, Biosorb PDX; Elite Performance Technologies, Solana Beach, Calif.) represent the advancing front in the application of absorbable devices in craniomaxillofacial surgery. The authors' share their experience and their studies of self-reinforced devices, which possess the highest strength and ductility of all bioabsorbable products.

Comparison of strength properties of poly-L/D-lactide (PLDLA) 96/4 and polyglyconate (Maxon) sutures: in vitro, in the subcutis, and in the achilles tendon of rabbits

Achilles tendon rupture is a common injury. Absorbable sutures are not commonly used because of their limited strength properties. Recently, sutures with prolonged strength retention properties have been developed. The aim of the study is to test the mechanical properties of recently developed poly-L/D-lactide (PLDLA) sutures in comparison with polyglyconate (Maxon) sutures. PLDLA (0.2 mm thick) and Maxon (4.0) sutures were studied in vitro by immersion in a buffered saline solution (pH 7.4). Tensile strength tests were done on sutures retrieved after 1-26 weeks. In vivo, they were implanted in the subcutis of 32 rabbits. Tensile strength tests were done on sutures retrieved after 1-6 weeks. The sutures were also used to repair the Achilles tendon in rabbits. Maximum force before breaking and percentage elongation of tendons were determined. Although PLDLA had a lower initial tensile strength than Maxon, PLDLA showed more prolonged tensile strength retention than Maxon. Tendons repaired with PLDLA, however, had a lower strength than Maxon-repaired tendons at six weeks (insignificant difference). PLDLA has more prolonged tensile strength properties compared with Maxon. Thus, PLDLA offers an alternative to Maxon in repair of the Achilles tendon.

The fate of resorbable poly-L-lactic/polyglycolic acid (LactoSorb) bone fixation devices in orthognathic surgery

PURPOSE

The aim of this study was to evaluate the long-term outcome of resorbable poly-L-lactic/polyglycolic acid (PLLA-PGA) bone fixation devices used for fixation of maxillary and mandibular osteotomies.

MATERIALS AND METHODS

Twelve patients were postoperatively evaluated. Eight patients who had undergone bilateral sagittal split mandibular osteotomies that had been fixed with PLLA-PGA screws were followed-up for up to 2 years postoperatively with radiographs. One of these patients underwent a bone biopsy for detailed histologic evaluation of the screw fixation sites. Two patients who had undergone mandibular symphyseal osteotomies were also radiographically evaluated at 18 months to 2 years postoperatively. Two patients who had Le Fort I osteotomies fixed with PLLA-PGA plates and screws underwent open exploration of the operated sites for visual examination.

RESULTS

All 8 mandibular osteotomy patients showed radiographic screw hole lucency immediately after surgery that remained unchanged in the first year after surgery. By 18 months postoperatively, all 48 screw holes showed near or complete trabecular bone fill. The bone biopsy of one screw hole at 2 years postoperatively showed complete fill with normal trabecular bone. No residual polymer material or fibrous scar was seen. The mandibular symphyseal sites showed complete elimination of all screw holes by 2 years postoperatively, with only faint evidence of intraosseous tunnels. The maxillary sites showed complete bone healing along the osteotomies and no evidence of residual fixation material or bone defects in the screw holes. No communication with the maxillary sinus was seen in the fixation sites.

CONCLUSION

This orthognathic patient series showed complete resorption of the PLLA-PGA fixation devices without osteolysis in maxillary and mandibular bone sites by 18 to 24 months after surgery.