An experimental study of the biomechanical stability of ultrasound-activated pinned (SonicWeld Rx+Resorb-X) and screwed fixed (Resorb-X) resorbable materials for osteosynthesis in the treatment of simulated craniosynostosis in sheep

Posterior cranial vault distraction in children with syndromic craniosynostosis: the era of biodegradable materials-a comprehensive review of the literature and proposed novel global application

Distraction osteogenesis is utilized to increase intracranial volume in the treatment of restrictive pathologies, most commonly syndromic synostosis. Children too young for open calvarial vault expansion or other systemic or local contraindications to a direct reconstructive approach benefit greatly from distraction osteogenesis, typically addressing posterior vault expansion. Wound infection, cerebrospinal fluid (CSF) leak, device failure, need for a second surgery for removal, and cost, are issues that can limit the use of this approach. These challenges are more pronounced in low- and middle-income countries (LMICs) due to lack of access to the device, the financial burden of the need for a second surgery, and the severity of the implications of infection and CSF leak. Over the last five decades, there has been an increased acceptance of bioresorbable instrumentation in craniofacial surgery. Poly L-lactic acid, polyglycolic acid, and polydioxanone are the most commonly used polymers. New resorbable fixation tools such as ultrasound-activated pins and heat-activated pins are superior to conventional bioresorbable screws in allowing attachment to thinner bone plates. In this paper, we present a review of the literature on cranial vault distraction and the use of bioresorbable materials and propose a novel design of a fully absorbable cranial distractor system using external magnetic distraction control, eliminating the need for external activation ports and a second surgery to remove the hardware. The application of this technology in LMIC settings could advance access to care and treatment options for patients with syndromic synostosis.

Remodelling of mandibular condylar head after fixation of fractures with ultrasound activated resorbable pins: A retrospective case series

The aim of this study was to assess whether the resorption of poly-lactic acid pins, used for condylar head fracture fixation, adversely affect remodelling of the condylar head. A retrospective review of patients was performed that underwent ORIF of CHF with ultrasound activated resorbable poly-lactic acid pins and had CT/CBCT scans of the condyle at least 18 months after surgery, at which point the fixation material was expected to be resorbed. We reviewed the size, shape and position of the condylar head and compared this to the normal side and compared this to the results of conservative management and ORIF with titanium screws in the literature. Most patients had condylar heads normally positioned and shaped, with minimal bone changes. The position of the condyle in the fossa, its shape and bone changes compare favourably with previous studies on CHF managed conservatively or with titanium screw fixation. There was no radiographic evidence of the pins after 18 months. In conclusion, ultrasound activated resorbable pins can provide suitable fixation for ORIF of condylar head fractures, avoiding the need for screw removal, and there was no evidence that the resorption process adversely affected the remodelling of the condylar head.

Laryngeal fracture treated with ultrasound-aided fixation using an absorbable plate system

Background

Laryngeal trauma is not a frequently encountered disease in routine clinical practice. Blunt trauma with thyroid fractures may leave permanent voice impairment and respiratory impairment due to scar stenosis, requiring appropriate treatment.

Case presentation

We describe a 38-year-old man was referred to our hospital for evaluation of inability to speak loudly and difficulty with high-pitched voice that had begun after a falling tree struck him on the anterior neck. He underwent successful fixation of fractures in their laryngeal cartilage after trauma by using the ultrasound-aided fixation system using an absorbable plate.

Conclusion

Laryngeal fracture is a rare entity in patients with blunt cervical trauma. Ultrasound-aided fixation using an absorbable implant system is effective for optimal reduction and fixation of fractured laryngeal cartilage, and may become an alternative method in patients with adhered and unossified cartilage.

Comparison of Extracapsular Stabilization Techniques Using an Ultrasonically Implanted Absorbable Bone Anchor (Weldix) after Cranial Cruciate Ligament Rupture in Cats-An In Vitro Study

Simple Summary

One reason for lameness in cats is the rupture of the cranial cruciate ligament. This ligament is located in the stifle joint and contributes to its stabilization during excessive forward movement and internal rotation of the tibia. One method for the surgical treatment of cranial ligament rupture is the placement of an extracapsular suture. Different materials and methods of suture fixation have been used in dogs and cats. This study investigated the use of a novel polylactide absorbable bone anchor that was implanted with ultrasound technology for suture fixation and compared this with suture fixation alone and fixation with a nonabsorbable bone anchor using an ex vivo modified limb-press model. For evaluation, distance measurements on radiographs were performed and the angles between defined bony structures were calculated. The acquired measurements accounted for both craniocaudal and mediolateral movements, and the results showed that the absorbable anchor could neutralize excessive movement within the stifle joint in two of three measurements and seems to be a good alternative to well-known surgical methods.

Abstract

Background: This study evaluated joint stability after surgical repair of cranial cruciate ligament (CrCL)-deficient stifle joints in cats using a novel absorbable polylactide bone anchor in an ex vivo model. Methods: Thirty-six hindlimbs from cats with intact (G_i group) and transected CrCLs were treated with fabellotibial suture alone (G_FW group), suture combined with an absorbable polylactide bone anchor (G_WD group), or suture combined with a nonabsorbable bone anchor (G_FT group), positioned in a limb press with predefined joint angles (stifle joint: 120 ± 5°; hock joint: 120 ± 5°) and loaded with 10%, 20%, and 30% of body mass (BM). Predefined points were measured on lateral radiographs and with a coordinate measurement machine. Distances on radiographs (mm) were measured and angles (°) were calculated to represent the craniocaudal movement and the internal rotation of the tibia. Results: There were no differences for craniocaudal movement between G_i and G_FW or G_FT, but for G_WD regarding angle measurement at 30% BM. For internal rotation, there was no significant difference between G_i and G_FW or G_WD, but for G_FT. Conclusion: The used absorbable polylactide bone-anchor was able to stabilize the stifle joint regarding internal rotation and craniocaudal movement as calculated from distance measurements.

Comparison of the Biomechanical Stiffness of Titanium and Sonic Weld RX Osteofixation Systems for Monoblock Zygomaticomaxillary Complex Fractures

ABSTRACT

Resorbable osteosynthesis systems are widely used for the fixation of zygomaticomaxillary complex (ZMC) fractures instead of titanium systems, because they do not have postoperative hardware-related complications. However, the strength of conventional resorbable systems is inferior to that of titanium systems. Recently, ultrasound-aided resorbable osteosynthesis systems, which have higher fixation than conventional resorbable osteosynthesis systems, have become available.The purpose of this study was to compare the mechanical stiffness of the ultrasound-aided resorbable and titanium osteosynthesis systems in a cadaveric monoblock ZMC fracture model. Three human cadaveric monoblock ZMC fracture models (6 zygomas) were created. The fixation materials included the titanium (Level One Fixation; KLS Martin, Germany) and ultrasound-aided resorbable osteofixation systems (SonicWeld RX; KLS Martin). The fixation methods included the 3-point (zygomaticofrontal [ZF], zygomaticomaxillary buttress, and inferior orbital rim [Group I]) and the 2-point (ZF + inferior orbital rim [Group IIa] and ZF + zygomaticomaxillary buttress [Group IIb]) fixations. Each fixation model was mechanically tested with a load of up to 100 N, based on the previously reported postoperative masseter muscle strength, and the stiffness was calculated. Titanium was found to be stiffer than SonicWeld RX, though not significantly different. The fixation points in decreasing order of stiffness were Group I, Group IIa, and Group IIb, though the differences were not significant. In conclusion, the 2-point fixation, including the ZF fixation with SonicWeld RX, can be used as an alternative to the 3-point titanium fixation, which is considered to be stronger and stiffer.

Comparison of the mechanical properties of biodegradable and titanium osteosynthesis systems used in oral and maxillofacial surgery

To guide the selection of osteosynthesis systems, this study compared the mechanical properties of biodegradable and titanium osteosynthesis systems. SonicPins Rx and xG were subjected to pull-out tests. Additionally, 15 biodegradable (Inion CPS 2.0 and 2.5 mm; LactoSorb 2.0 mm; Macropore 2.0 mm; Polymax 2.0 mm; BioSorb FX 2.0 mm; ResorbX 2.1 mm; Osteotrans-MX 2.0 mm with plate thicknesses 1.0 and 1.4 mm; SonicWeld Rx_plate/Rx_pins, xG_plate/Rx_pins and xG_plate/xG_pins 2.1 mm without and with tapping the burr hole) and six titanium (CrossDrive (2006), CrossDrive (2018), MaxDrive; all 1.5 and 2.0 mm) straight, four-hole osteosynthesis systems were evaluated. All systems were subjected to tensile, bending and torsion tests. Pull-out loads of the SonicPins were comparable (P = 0.423). Titanium systems’ tensile loads were higher than biodegradable systems (P < 0.001). CrossDrive (2018) and MaxDrive systems’ tensile and torsional stiffness were lower, accompanied with higher ductility, than corresponding CrossDrive (2006) systems (P < 0.001). Bending stiffness of 1.5 mm titanium systems was comparable to, and of the 2.0 mm systems higher than, all biodegradable systems (P < 0.001). Regarding biodegradable systems, Inion CPS 2.5 mm had highest tensile load and torsional stiffness, SonicWeld 2.1 mm highest tensile stiffness, and BioSorbFX 2.0 mm highest bending stiffness (P < 0.001). On the basis of the results of this study, the CrossDrive (2018) and MaxDrive 1.5 mm titanium systems are recommended for midface fractures (e.g., zygomatic or maxillary fractures) and osteotomies (e.g., Le Fort I osteotomy), and the CrossDrive (2018) and MaxDrive 2.0 mm titanium systems for mandibular fractures and osteotomies when a titanium osteosynthesis system is used. When there is an indication for a biodegradable osteosynthesis system, the SonicWeld 2.1 mm or BioSorbFX 2.0 mm are recommended for midface fractures and osteotomies, and the Inion CPS 2.5 mm biodegradable system for mandibular osteotomies and non-load bearing mandibular fractures, especially when high torsional forces are expected (e.g., mandibular symphysis fractures).

Ultrasound-Activated Bioresorbable Osteosynthesis in the Treatment of Craniosynostosis

ABSTRACT

The purpose of this study is to estimate the incidence of fixation-related complications following ultrasound-activated biodegradable osteosynthesis (UBO) in the treatment of craniosynostosis. The authors searched MEDLINE, PubMed, Embase, Google Scholar, and Cochrane Library from January 2005 to January 2020 for clinical studies reporting the use of UBO for fixation in the treatment of craniosynostosis. The primary outcome was the incidence of fixation-related complications, including unstable fixation; swelling, plate visibility, or palpability; infection; inflammation, sinus formation, and discharge; implant exposure; reoperation or implant removal. The pooled incidence rates were estimated using random-effects models. Of 155 studies identified, 10 were included, representing 371 patients. Forty-six (12.4%) patients presented fixation-related complications. The incidence rates of swelling/visibility/palpability, infection, and reoperation/implant removal were pooled based on the available data. The pooled incidence rate of chronic swelling/visibility/palpability was 0.21 (95% confidence interval [CI], 0.05-0.43). Sensitivity analysis by omitting the outlier study demonstrates that the incidence of swelling/visibility/palpability was 0.07 (95% CI, 0.04-0.11). The pooled incidence rate of infection and reoperation/implant removal was 0.07 (95% CI, 0.01-0.16) and 0.04 (95% CI, 0.01-0.09), respectively. Results show that although UBO can provide stable fixation, chronic swelling/visibility/palpability, infection, and reoperation for removal are not uncommon. Based on the literature, the authors recommend judicious use of UBO in patients with large frontorbital advancement and in the area of the coronal suture or other sites with thin overlying skin/subcutaneous tissue. The high possibility of chronic swelling/palpability/visibility during degradation, needs to be discussed preoperatively.

Risk factors in bone augmentation procedures

Bone augmentation is an extremely common procedure in implant dentistry today because of significant advancements with reactive biomaterials, a better understanding of the mechanism of action that is found with growth factors contained in platelets, and improvements in surgical techniques. The expectation is for the surgeon to place the dental implant in the position that best serves the requirements of the prosthetic restorations. With the increasing demands that patients have for ideal prosthetic results, surgeons are expected to predictably augment both hard and soft tissues to provide the anticipated esthetic and functional outcomes. Bone grafting can be performed before, during, and after the implant placement; however, these augmentation procedures come with increased cost, the risk of complications such as infection or failure, and lengthening of the total treatment time. In addition, a plethora of grafting materials are available commercially, where they are often inadequately studied, or there is minimal information regarding their predictability or long-term success, or ability to support dental implants. It is clear that although the surgical field has seen major progress since early implant surgical techniques in the 1980s, major challenges still exist with hard tissue augmentation procedures. This review will discuss these challenges that are increased and often specific to bone graft healing, and which are becoming more common as implant site development often requires bone augmentation to improve volume or contour deficiencies. The risk factors that patients may present with that will affect outcomes with bone augmentation procedures are identified, and recommendations for the prevention of complications or managing complications once they have occurred are provided.

Experience with resorbable sonic pins for the attachment of distraction devices in posterior cranial vault distraction operations

BACKGROUND

Distraction techniques are effective methods for the treatment of craniosynostoses when a significant gain of an intracranial volume is required. However, this technique raises some challenges at different stages of the treatment. While installing the distractors in patients with thin calvarial bone, there is a risk of dural damage from the titanium screws. The need for wide exposure of the devices and the screws during removal causes soft tissue damage and bleeding.

OBJECTIVE

This study aimed to evaluate sonic pin use in the distraction procedures.

METHODS

Resorbable sonic pins were used in 11 consecutive posterior cranial vault distraction procedures to attach distraction devices to the calvarial bone.

RESULTS

This method allowed for a less traumatic and faster removal of the devices without the risk of leaving foreign bodies in the wound. In three out of 11 cases on follow-up, displacement of proximal distractor footplate and partial relapse of distraction were detected. Though there was a smaller volume increase in these patients, all of them benefited clinically from the PCVD and did not require reoperations.

CONCLUSIONS

This method allows a strong and stable attachment of the distractor devices to the cranial vault bones with a reduced risk of dural tears due to the screws. It also allows for easier and less traumatic device removal.

Comparison of Titanium and Bioresorbable Plates in "A" Shape Plate Properties-Finite Element Analysis

(1) Background: The main disadvantage of rigid fracture fixation is remain material after healing period. Implementation of resorbable plates prevents issues resulting from left plates. The aim of this study is to compare the usage of bioresorbable and titanium “A” shape condyle plate in condylar fractures. (2) Methods: Thickness of 1.0 mm, height of 31 mm, and width of 19 mm polylactic acid (PLLA) and titanium “A” shape plate with 2.0 mm-wide connecting bar and 9 holes were tested with finite element analysis in high right condylar neck fracture. (3) Results: On bone surface the highest stress is on the anterior bridge around first hole (approx. 100 MPa). The highest stress on screws is located in the first screw around plate in the anterior bridge and is greater in titanium (150 MPa) than PLLA (114 MPa). (4) Conclusion: Pressure on bone in PLLA osteosynthesis is two times higher than in titanium fixation. On small areas where pressure on bone is too high it causes local bone degradation around the fracture and may delay the healing process or make it impossible. Fixation by PLLA is such flexible that bone edges slide and twist what may lead to degradation of callus.

Trimming of Absorbable Plates and Screws through Smoothing by Multiple Sonic Activation Procedures Can Increase Local Tissue Reactions in Children with Cranial Fixations

OBJECTIVE

The aim of this paper was to investigate the local reactions due to the melting of absorbable plates and screws after trimming through smoothing by multiple sonic activation procedures (MSAP).

BACKGROUND

Drilling or smoothing by MSAP is performed for the trimming of the absorbable plates and screws for cranial fixation in children. Compared to drilling, smoothing by MSAP is suspected to more commonly cause local tissue reactions; thus, the issue was examined herein.

METHODS

For 90 children with smoothing by MSAP and 83 children with drilling procedures who underwent cranial fixation using absorbable plates and screws, the type, time of onset, and incidence of the local reactions were investigated.

RESULTS

Swelling was the most common reaction, followed by inflammatory reactions with itching, heating, skin-penetrating drainage, and pus formation. The mean time of onset of the local reaction was 10.0 ± 2.3 months after surgery. Local reactions occurred in 30% of the children in the group with smoothing by MSAP, and in 7.2% of the children in the group with drilling, showing a statistically significant difference between the two groups (p < 0.001).

CONCLUSION

It was concluded that drilling rather than smoothing by MSAP to change the shapes of the absorbable plates and screws in cranial fixation can reduce the local reactions.

The State of Technology in Craniosynostosis

INTRODUCTION

Craniosynostosis, the premature fusion of ≥1 cranial sutures, is the leading cause of pediatric skull deformities, affecting 1 of every 2000 to 2500 live births worldwide. Technologies used for the management of craniofacial conditions, specifically in craniosynostosis, have been advancing dramatically. This article highlights the most recent technological advances in craniosynostosis surgery through a systematic review of the literature.

METHODS

A systematic electronic search was performed using the PubMed database. Search terms used were "craniosynostosis" AND "technology" OR "innovation" OR "novel.' Two independent reviewers subsequently reviewed the resultant articles based on strict inclusion and exclusion criteria. Selected manuscripts deemed novel by the senior authors were grouped by procedure categories.

RESULTS

Following review of the PubMed database, 28 of 536 articles were retained. Of the 28 articles, 20 articles consisting of 21 technologies were deemed as being novel by the senior authors. The technologies were categorized as diagnostic imaging (n = 6), surgical planning (n = 4), cranial vault evaluation (n = 4), machine learning (n = 3), ultrasound pinning (n = 3), and near-infrared spectroscopy (n = 1).

CONCLUSION

Multiple technological advances have impacted the treatment of craniosynostosis. These innovations include improvement in diagnosis and objective measurement of craniosynostosis, preoperative planning, intraoperative procedures, communication between both surgeons and patients, and surgical education.

Novel ultrasound assisted suture anchor system using the BoneWelding® technology yields a comparable primary stability in osteopenic and healthy human humeri as a benchmark anchor

Introduction

The aim of this biomechanical study was to evaluate the primary stability of the SportWelding® Sombrero 3.6 mm suture anchor system in osteopenic and healthy cadaveric humeri.

Methods

The Sombrero® and BioCorkscrew® anchors were deployed in 8 osteopenic and 4 healthy cadaver humeri after the bone mineral density (BMD) measurements of the 32 specimens. Both anchors were loaded with a USP Nr. 2 FiberWire® suture. An established cyclic testing protocol was performed. The maximum failure load (Fmax), the system displacement and the modes of failure were recorded.

Results

The F_max and system displacement of the Sombrero® in osteopenic and healthy humeri was equivalent to the Bio-Corkscrew® benchmark anchor; there were no significant differences in the maximum failure loads and system displacement values. Only anchor and suture dislocations were observed; suture ruptures did not occur.

Conclusion

This study shows that the Sombrero® yields similar maximum failure loads and system displacement values as the established Bio-Corkscrew® benchmark anchor. The primary stability of the Sombrero® and Bio-Corkscrew® seems to be independent of the bone mineral quality. This relatively small-sized polymer anchor is independent of the BMD and may be an alternative to established suture anchors in rotator cuff repair.

The Use of Poly-d,l-lactic Acid (PDLLA) Devices for Bone Augmentation Techniques: A Systematic Review

Poly-d,l-lactic acid (PDLLA) has been proposed in dentistry for regenerative procedures in the form of membranes, screws, and pins. The aim of this review was to evaluate the efficacy of bone augmentation techniques using PDLLA devices. A literature search was carried out by two independent and calibrated reviewers. All interventional and observational studies assessing the efficacy of bone augmentation techniques using PDLLA devices were included. Six studies were included. The relevant variability of design and methods impeded any qualitative or quantitative comparison. Ease of handling, absence of a re-entry phase, moldability of foils, and good soft-tissue response were appreciated characteristics of PDLLA devices. Some drawbacks such as the risk of membrane exposition, a prolonged adsorbability, and a tendency to a fibrous encapsulation of the PDLLA devices have been described, although the clinical significance of these findings is unclear. Clinical data about PDLLA devices for bone regeneration are very scarce and heterogenous. Well-designed randomized controlled trials comparing the use of PDLLA foils and pins with conventional membranes for bone regeneration are strongly encouraged in order to understand the real clinical benefits/drawbacks of this technique.

Biomechanical evaluation of novel ultrasound-activated bioresorbable pins for the treatment of osteochondral fractures compared to established methods

BACKGROUND

Osteochondral injuries often lead to osteoarthritis of the affected joint. All established systems for refixation of osteochondral defects show certain disadvantages. To address the problem of reduced stability in resorbable implants, ultrasound-activated pins were developed. By ultrasound-activated melting of the tip of these implants, a more secure anchoring is assumed.

MATERIALS AND METHODS

The aim of the study was to investigate if ultrasound-activated pins can provide secure fixation of osteochondral fragments compared to screws and conventional resorbable pins. In a biomechanical laboratory setting, osteochondral fragments of the medial femoral condyle of sheep were refixated with ultrasound-activated pins [US fused poly(L-lactide-co-D,L-lactide) (PLDLLA) pins], polydioxanone (PDA) pins and conventional titanium screws. Anchoring forces of the different fixation methods were examined, registered and compared concerning shear force and tensile force.

RESULTS

Concerning the pull out test, the US fused PLDLLA pins and titanium screws (~122 N and ~203 N) showed comparable good results, while the PDA pins showed significantly lower anchoring forces (~18 N). Examination of shear forces showed a significantly higher anchoring of the screws (~248 N) than the US fused PLDLLA pins (~218 N). Nevertheless, the US fused PLDLLA pins could significantly outperform the PDA pins (~68 N) concerning shear forces.

CONCLUSION

The US fused PLDLLA pins demonstrated a comparable anchorage to the fixation with screws, but were free from the disadvantages of metal implants, i.e. the need for implant removal. The PDA pin application showed inferior biomechanical properties.

[Biodegradable fixation systems in pediatric craniofacial surgery: 10-year experience with 324 patients]

INTRODUCTION

Over the past 15 years, resorbable materials have been successfully used for osteosynthesis, but their high cost prevents widespread application. However, the use of resorbable systems could be a method of choice, especially in treatment of children in the active growth period. Obviously, biodegradable materials not only are highly competitive with known metal constructs in terms of fixation rigidity, biocompatibility, and a low risk of infection but also have an undeniable advantage, such as gradual resorption allowing quick return of damaged bones to the physiological conditions of functioning. A special feature of bioresorbable systems is that they can be assembled using ultrasonic welding, which greatly facilitates the fixation process and also provides necessary rigidity, even in cases of joining very thin bones when reliable fixation with screws is impossible.

MATERIAL AND METHODS

Over the past 10 years, we have used biodegradable systems in 324 patients. In 244 of them, we used traditional (plate/screw) systems; in 80 cases, an ultrasonic welding system was chosen for osteosynthesis.

RESULTS

In the present work, we discuss, based on clinical evidence, the advantages and disadvantages of both fixation systems for reconstructive craniofacial surgery in children.

Treatment of fractures of the mandibular condylar head with ultrasound-activated resorbable pins: early clinical experience

Controversy continues about the benefits and disadvantages of open reduction and internal fixation of fractures of the condylar head. Once a decision to treat surgically has been made, an appropriate method of fixation must be chosen. Standard titanium fixation has a number of complications, including the risk of protrusion of the screw beyond the condylar head and the possible need for removal later. Resorbable fixation is an alternative, and ultrasound-activated resorbable pins are a new innovation. We have treated a series of 15 patients with 17 fractures of the condylar head, in which the use of ultrasound-activated resorbable fixation has provided adequate strength and stability during early healing. Complications included technical difficulties in achieving complete anatomical reduction as a result of fragmentation of the condylar head, and three facial nerve palsies, two of which recovered within three months. No pins failed, and there was no sign of instability during healing.

Primary stability and osseointegration of dental implants in polylactide modified bone - A pilot study in Goettingen minipigs

The present study aimed to evaluate primary stability (PS) and osseointegration of dental implants in polylactide [70/30 poly(l-lactide-co-d, l-lactide); (PLDLA)] modified bone in 30 Goettingen minipigs. Each animal received three implants per jaw quadrant. In a split-mouth design, one side of the maxilla and mandible was randomly allocated to the experimental treatment (PLDLA applied into the drill hole before implantation), while the contralateral sides served as intraindividual controls (no PLDLA applied). The required insertion torque and the implant stability quotient (ISQ) were measured during implantation. ISQ, volume density (VD) of new bone formation (NBF), and the bone-implant contact (BIC) were evaluated at the end of the observation period (1, 3, 6, 12, and 24 months, respectively) in six animals each. Across all study groups, the PLDLA treatment resulted in a) a comparable insertion torque, b) an equivalent ISQ, c) a reduced BIC, and d) a reduced VD of NBF, as opposed to the untreated controls. In conclusion, the PLDLA treatment did not affect the PS, but rather led to an impaired osseointegration, which was particularly strong in the compact mandibular bone, and decreased in the spongious maxillary bone. PLDLA induced anchoring in spongious bone should be evaluated in further investigations.

Mechanical Analysis of Ultrasound-Activated Pins and Resorbable Screws: Two Different Techniques to Fixate Osteosynthesis in Craniosynostosis Surgery

PURPOSE

Ultrasound activation of resorbable pins directly into drilled holes of the calvarium was introduced to overcome the time-consuming installation in the resorbable osteosynthesis fixation in craniosynostosis surgery. There is paucity in the data comparing the mechanical properties of resorbable screws and ultrasound-activated pins produced by different manufacturers. The aim of this experimental study was to compare the mechanical properties of ultrasound-activated pins and resorbable screws.

METHODS

A mechanical testing machine was used to characterize the mechanical performance of screws and ultrasound pins. The screws and pins were tested individually in 2 directions with respect to the longitudinal axis: vertical, that is, axial pull-out strength and horizontal, that is, shear strength. The mean maximum strength of fixation was determined. Broken screws and pinheads were analyzed by a scanning electron microscope to determine the site of fracture.

RESULTS

All of the resorbable screws and pins broke at the point where the device enters bone. In pull-out testing, the mean maximum strength of the ultrasound-activated pins was 30.5 ± 5.4 N and that of the resorbable screws was 54.0 ± 0.3 N. In shear testing, the mean maximum strength of ultrasound-activated pins was 57.1 ± 20.1 N and that of the resorbable screws was 53.9 ± 0.4 N.

CONCLUSIONS

In their intended configuration, there is no clinically significant difference in fixation strength between ultrasound-activated pins and resorbable screws.

Evaluation of local cancellous bone amelioration by poly-L-DL-lactide copolymers to improve primary stability of dental implants: a biomechanical study in sheep

OBJECTIVES

The aim of this study was to evaluate the clinical performance of local cancellous bone amelioration by a 70:30 poly-(L-lactide-co-D,L-Lacide) copolymer with two different implant designs on primary stability and after 4 and 12 weeks of healing time.

MATERIAL AND METHODS

In six sheep, n = 36 implants (TH) with a conditioned, sandblasted, thermal acid-etched micro-rough surface and n = 36 implants (NB) with a highly crystalline and phosphate-enriched anodized titanium oxide surface were placed in the pelvic bone. Using an ultrasound-based process named Constant Amelioration Process (CAP), half of peri-implant trabecular bone structures were locally tested with 70:30 poly-(L-lactide-co-D,L-Lacide) copolymer in both implant groups, TH and NB. The CAP technology employs ultrasonic energy to liquefy 70:30 poly-(L-lactide-co-D,L-Lacide) which enters the inter-trabecular space, leading to local reinforcement of the cancellous bone structure after solidification of the copolymer. The CAP test group was compared with reference implants placed with the conventional site preparation according to the manufacturers' description. Primary stability was assessed by the measurement of torque-in values and implant stability quotient (ISQ; n = 18 per group). Secondary stability was analyzed by biomechanical removal torque testing after 4 and 12 weeks (n = 9 per group).

RESULTS

Insertion torque value (23.3 N cm ± 13.6) of reference TH implants demonstrated a statistically significant (P = 0.00) difference in comparison with test TH implants (41.9 N cm ± 19.5). Reference NB implants revealed a statistically significant (P = 0.03) lower insertion torque value (23.7 N cm ± 13.5) than test NB implants (39.7 N cm ± 18.6). ISQ values increased for all implants from initial implant placement until sacrifice at 12 weeks. Reference TH implants tended to result in an increase in torque values from 4 weeks (181.9 N cm ± 22.8) to 12 weeks (225.7 N cm ± 47.4). This trend could be also proven for implants of test sites (4 week: 176.8 N cm ± 24.1; 12 week: 201.5 N cm ± 53.4). For reference, NB implants a non-significant increase in removal torque values from 4 weeks (146. 7 N cm ± 18.0) to 12 weeks (170.2 N cm ± 40.4) was observed. Removal torque values of test NB implants did not increase from 4 weeks (153.3 N cm ± 21.5) to 12 weeks (146.1 N cm ± 37.5).

CONCLUSION

Biomechanical data proved significantly enhanced primary stability of dental implants after local amelioration without long-term sequelae and irrespective of implant design. After 4- and 12-week healing time, removal torque of locally test implants was as high as for control implants, and osseointegration was therefore not influenced by the CAP process. No correlation between ISQ values and torque values was found.

The value of ultrasound-assisted pinned resorbable osteosynthesis for cranial vault remodelling in craniosynostosis

Resorbable osteosynthesis is a widespread tool in craniofacial surgery, however only a limited number of studies have focused on ultrasound-assisted pinned resorbable systems in the treatment of craniosynostosis. Thirty-eight children with various types of craniosynostosis including scaphocephaly, trigonocephaly, anterior and posterior plagiocephaly were treated using the Sonic Welding resorbable osteosynthesis system. All patients were evaluated for operation time, stability of the surgical results, rate of local infections and visibility or palpability of the osteosynthesis material in the follow-up ranging from 15 to 21 month. Mean operation time was not significantly higher compared to conventional osteosynthesis material and all remodelled cranial vaults showed immediate stability. Only one patient showed signs of an inflammatory skin reaction, which recovered spontaneously. The number of palpable or visible plates, respectively, increased during the first months with a maximum at 12 months (34 (89%) plates palpable, 26 (68%) plates visible). After this time point, the number decreased continuously until the end of the follow-up period at 21 months when 3 (20%) plates were palpable, 0 (0%) plates were visible). Ultrasound-assisted pinned resorbable systems seem to be a promising tool in craniofacial surgery providing a timesaving and stable osteosynthesis. An initial swelling of the plates during the first 12 months before the complete degradation might result in a palpable and visible bulge.

The clinical usefulness of ultrasound-aided fixation using an absorbable plate system in patients with zygomatico-maxillary fracture

Background

Ultrasound-aided fixation is a recently developed alternative method of treatment of zygomatico-maxillary (ZM) fracture, and it can resolve the problems of excessive torsion force and subsequent fractures of screws. We conducted this study to evaluate the clinical usefulness of ultrasound-aided fixation as compared with the conventional fixation method using a drill and an expander in patients with ZM fracture.

Methods

We conducted a retrospective study in 35 patients with ZM fracture who had been treated at our hospital during a period ranging from March of 2008 to December of 2010. We divided them into two groups: an ultrasound-aided fixation group, comprising 13 patients who underwent ultrasound-aided fixation (SonicWeld Rx, KLS Martin), and a conventional group, comprising 22 patients who underwent conventional fixation (Biosorb FX, Linvatec Biomaterials Ltd.). We compared such variables as sex, direction, age at operation, follow-up period, operation duration, number of fixed holes, and time to discharge between the two groups.

Results

The ultrasound-aided fixation reduced the operation duration by about 30 minutes as compared with that of conventional fixation. There was no significant difference in follow-up period, number of fixed holes, or time to discharge between the two groups. Furthermore, there were no complications in either group.

Conclusions

The ultrasound-aided fixation of fractured ZM bone using an absorbable implant system is safe and effective in promptly reducing the bone fracture and providing satisfactory cosmetic outcomes over time.

Cochlear implant fixation using resorbable mesh

In this article we describe a new method of cochlear implant receiver-stimulator fixation using a resorbable poly (D,L) lactic acid mesh. We conducted a retrospective case review at a tertiary referral center; 10 pediatric and 4 adult patients had undergone cochlear implantation during the period from February to October 2008. Resorbable poly (D,L) lactic acid mesh and pins were used for fixation of the cochlear implant receiver stimulator. The receiver stimulator was assessed for stability/migration, and the scalp flap/incision were evaluated for allergic reactions, infections, and healing problems. With an average follow-up of 17.2 months, no patients had migration of the receiver stimulator, and there was no evidence of infection, wound dehiscence, or allergic reaction. Early results indicate that fixation of a cochlear implant receiver stimulator using resorbable mesh is well tolerated and provides good stability without device migration. Resorbable mesh fixation of the receiver stimulator is a reasonable alternative technique for cochlear implantation.

Ultrasound-aided resorbable osteosynthesis of fractures of the mandibular condylar base: an experimental study in sheep

We evaluated the osteosynthesis of condylar fractures using resorbable mini plates and ultrasound-aided insertion of pins clinically and histologically. Stability was greater than that with resorbable screws because of the fusion of pin and plate. Long term evaluation showed complete resorption of the polymeric osteosynthesis material.

Fixation of Le Fort I osteotomies with poly-DL-lactic acid mesh and ultrasonic welding--a new technique

PURPOSE

This report describes a technique for use of resorbable mesh (Resorb-X) and an ultrasonic sonotrode unit (SonicWeld Rx) to bond a pin (SonicPin Rx) to the mesh and underlying bone for Le Fort I osteotomy fixation, precluding the need to tap, shortening the time needed for fixation, and eliminating many disadvantages of titanium. In total, 659 cases have been performed from October 2005 through December 2010. This study examined the first 103 consecutive Le Fort osteotomies performed with this resorbable system and thus those with the longest follow-up.

MATERIALS AND METHODS

One hundred three consecutive patients who had completed growth and presurgical orthodontics were operated on using the Resorb-X plating system and SonicWeld Rx. Intraoperative adverse events were monitored and a minimum 12-month postoperative follow-up for complications was completed.

RESULTS

One patient (0.9%) had maxillary mobility at initial postoperative evaluation that resolved without malocclusion. Two patients (1.9%) exhibited signs of residual soreness and swelling in the maxilla, attributed to sterile abscess formation. At last follow-up, all patients demonstrated a clinically stable maxilla with correction of their malocclusion.

CONCLUSION

Use of ultrasonic-aided pins in fixation of resorbable mesh plates, in Le Fort I osteotomies, is a viable technique and superior resorbable plating system because it is easy to use, results in adequate fixation strength, and shortens time of application by eliminating the need for tapping. In addition, this resorbable system eliminates many disadvantages associated with using all-titanium fixation.

Ultrasound-aided fixation of biodegradable implants in pediatric craniofacial surgery

PURPOSE

Bioresorbable implant systems have been used for the rigid fixation of cranial and facial bones. A relatively recent advancement has been the fixation of these implants using an ultrasonic device. Published reports with such a device in pediatric craniofacial surgery have been limited. We report our experience with ultrasound-aided fixation of bioresorbable implants in the craniofacial surgery of children.

METHODS

We retrospectively examined the clinical information, complications and outcome following the use of a commercially available ultrasound-aided bioresorbable implant system (SonicWeld Rx™, KLS Martin, Jacksonville, Fla., USA) during craniofacial surgery by University of Florida College of Medicine Jacksonville surgeons. Follow-up was obtained via clinical examination or telephone interview.

RESULTS

Over a period of 3 years, 37 pediatric patients (age range: 2 months to 16 years) had placement of these implants for immediate bony fixation during craniofacial procedures. Pathology consisted mainly of craniosynostosis (n = 19), and trauma (n = 16). Twenty-eight had combined craniofacial procedures; 9 patients had facial procedures. Reoperation was performed for: wound infection (n = 1), plate extrusion (n = 1). Delayed subcutaneous plate-related swelling was seen in 5 patients (4 were infants) and had a benign clinical course. Good cosmetic outcomes were seen in all patients.

CONCLUSIONS

The use of a bioresorbable implant system with ultrasound-aided pin fixation in pediatric craniofacial surgery achieves rapid fixation with minimal morbidity and good cosmetic outcome. This system is easy to use and provides reliable stability in the setting of pediatric trauma and craniosynostosis.

Ultrasound-aided fixation of a biodegradable cranial fixation system: uses in pediatric neurosurgery

OBJECT

Bioresorbable implant systems have been used in neurosurgery for the rigid fixation of cranial and facial bones. A relatively recent advancement has been the fixation of these implants using an ultrasonic device. The experience with such a device in neurosurgical practice has been limited. The authors report on their experience with ultrasound-aided fixation of bioresorbable implants in pediatric neurosurgical practice.

METHODS

The study consisted of 2 parts. The retrospective portion consisted of a chart review of pertinent clinical information, complications, and outcomes after the use of a commercially available ultrasound-aided bioresorbable implant system (SonicWeld Rx, KLS Martin L.P.). Follow-up was obtained in all patients via clinical examination or telephone interview. The prospective portion of the study consisted of video analysis of the implantation technique in a routine craniotomy. Implantation times were measured, and delays during treatment were noted.

RESULTS

Over a period of 2 years, 28 consecutive patients underwent placement of these implants for bone fixation during craniotomies or craniofacial reconstructions. The only complication was seen in a child with Crouzon syndrome, who had a wound infection caused by Serratia sepsis from a central venous line infection. There were no repeated operations for implant-related swelling, and no cases of premature plate resorption, bone instability, or settling. In vivo, the average time required to implant a resorbable pin with this system was 22 seconds.

CONCLUSIONS

The use of a bioresorbable implant system with ultrasound-aided pin fixation in pediatric neurosurgery cases achieved adequate stability with few complications. This system was easy to use and provided rapid fixation of implants.