Resorbable plate osteosynthesis of dislocated or pathological mandibular fractures: a prospective clinical trial of two amorphous L-/DL-lactide copolymer 2-mm miniplate systems

The purpose of this study was to evaluate the indication for resorbable miniplates in traumatic and pathological mandibular fractures. Two resorbable miniplate systems, the 2.0-mm MacroSorb (Macropore, San Diego, Calif.) and the PolyMax (Synthes, Oberdorf, Switzerland), were prospectively used in 24 mandibular osteosyntheses. Made from amorphous 70:30 poly-L/DL-lactide, amorphous copolymer plates have not yet been evaluated for mandibular osteosyntheses. The main advantage of the amorphous copolymer-structure is continuous hydrolysis through water penetration into the implant body during the first 6 months. Hydrolysis breaks the copolymer chains into smaller particles that later become degraded through phagocytotic cells. Twelve patients, aged 13 to 83 years, were treated after providing informed consent. Fourteen dentate patients with moderately dislocated traumatic fractures and two edentulous atrophic and dislocated traumatic mandibular fractures were treated. Two patients with pathological fractures due to osteomyelitis received osteosynthesis after sequestrectomy. Histological specimens of the plates, screws, and surrounding soft tissues were taken after 3, 6, 9, and 12 months in secondary dental implant operations. A total of 22 osteosyntheses healed well without clinical or radiological signs of dislocation, insufficient or excess formation of callus, pseudarthrosis, or plate fracture. The follow-up time ranged from 4 to 22 months. One patient with osteomyelitis worsened because of widespread osseous infection, and one with atrophic fracture developed a bland fibrous pseudarthrosis. The histological specimens showed a moderate inflammatory foreign body reaction. No sinuous drainage or clinically apparent inflammation occurred. The presented osteosynthesis systems showed reliable stability for mandibular osteosynthesis in cooperative patients; however, two treatment failures occurred (8 percent). Disadvantages of the resorbable osteosyntheses were costs, greater diameter, screw breakage, and the need to place the screws vertically to the plate. The use of resorbable osteosyntheses in dislocated fractures should be further evaluated in controlled studies.     

Treatment of mandibular angle fractures with a matrix miniplate: a preliminary report

Mandibular angle fractures are technically challenging, and a spectrum of techniques for treatment of these fractures has been proposed in the literature. Currently, fixation with one or two miniplates has become a widely accepted method of providing internal fixation and eliminating the need for postoperative maxillomandibular fixation. In this study, the utility of a single 2.0-mm matrix miniplate for mandibular angle fracture management was examined. In a laboratory biomechanical analysis, the overall stability of the single 2.0-mm matrix miniplate compared favorably with two 2.0-mm miniplates in a simulated fracture setting. The matrix miniplate demonstrated an overall better intrinsic stability, more resistance to out-of-plane fracture movement, and a higher load tolerance when motion out-of-plane was challenged. Clinically, the matrix miniplate performed well. In a series of 22 consecutive patients, there were no cases of nonunion, malunion, or plate failure. Two patients developed infection that was managed in both cases by drainage with maintenance of the miniplate. Both went on to full union. These results compare very favorably to previously published series using one or two miniplates.     

The fate of plates and screws after facial fracture reconstruction.

Rigid plate and screw fixation is the mainstay of treatment for complex fractures of the facial skeleton. Complications of plate and screw fixation include prominence, infection, exposure, and migration. Five hundred and seven patients undergoing plate and screw fixation for facial fractures (1112 fractures) from 1983 to 1988 were followed for complications. Sixty-one patients (12 percent) required hardware removal. The location on the facial skeleton influenced symptoms and the rate of hardware removal. Infection and exposure may be decreased with antiseptic irrigations, avoiding mucosal damage, attention to proper mucosal closure, and correct placement of plates. Prominence may be decreased by the use of microplates in the supraorbital, frontal, and naso-orbital-ethmoid locations.     

The use of miniplates in craniomaxillofacial surgery

Miniplates were used in craniomaxillofacial surgery for fixation in the skull, maxilla, and/or mandible in 74 patients with minimal or no intermaxillary wiring. Procedures included forehead and orbital repositioning, frontofacial advancement, Le Fort III and particularly Le Fort I osteotomies, as well as mandibular osteotomies and fracture repair. The miniplates provided stable fixation and, compared with other techniques, improved airway safety. The complication rate was low: there were no infections, but two plates (1 percent) became exposed in the buccal sulcus. Although application of miniplates lengthened surgery and increased the cost of the procedure, the savings in intensive care monitoring more than offset these costs. The stability of fixation minimizes the opportunity to reposition the fragments postoperatively with training elastics. Therefore, meticulous technique is mandatory, with particular emphasis on passive fitting of the plates and precise drilling of screw holes.     

Resorbable PLLA-PGA plate and screw fixation in pediatric craniofacial surgery: clinical experience in 1883 patients

The need to provide rigid bony fixation in the surgical treatment of craniofacial deformities has inspired an on-going evolution of surgical innovations and implants. Because of the young age of many treated craniosynostosis patients and the unique pattern of cranial vault growth, the extensive implantation of metal devices is potentially problematic. The use of resorbable plate and screw devices offers all of the benefits of rigid fixation without many of their potential risks. Since the introduction of resorbable plate and screw devices in 1996, tens of thousands of craniofacial patients have received implants, but long-term results from a large series have yet to be reported. A combined prospective and retrospective analysis was done on 1883 craniosynostosis patients under 2 years of age treated by 12 surgeons from seven different geographic locations over a 5-year period who used the same type of resorbable bone fixation devices (poly-L-lacticpolyglycolic copolymer). Specifically, the incidence of postoperative infection, fixation device failure, occurrence of delayed foreign-body reactions, and the need for reoperation resulting from device-related problems were determined. Technical difficulties and trends in device use were also noted. From this series, significant infectious complications occurred in 0.2 percent, device instability primarily resulting from postoperative trauma occurred in 0.3 percent, and self-limiting local foreign-body reactions occurred in 0.7 percent of the treated patients. The overall reoperation rate attributable to identifiable device-related problems was 0.3 percent. Improved bony stability was gained by using the longest plate geometries/configurations possible and bone grafting any significant gaps across plated areas that were structurally important. The specific types of plates and screws used evolved over the study period from simple plates, meshes, and threaded screws to application-specific plates and threadless push screws whose use varied among the involved surgeons. This report documents the safety and long-term value of the use of resorbable (LactoSorb) plate and screw fixation in pediatric craniofacial surgery in the infant and young child. Device-related complications requiring reoperation occurred in less than 0.5 percent of the implanted patients, which is less frequent than is reported for metallic bone fixation. Resorbable bone fixation for the rapidly growing cranial vault has fewer potential complications than the traditional use of metal plates, screws, and wires.     

Treatment of mandible fractures using bioabsorbable plates

This study evaluated the short-term outcome of treating fractures of the mandible with bioabsorbable plates. Sixty-nine fractures of the mandible in 49 patients were treated by open reduction and internal fixation using bioabsorbable plates and 2.4-mm, 2.0-mm, and 1.5-mm pretapped screws. The duration of intermaxillary fixation ranged from 0 to 23 days, with a mean of 4.6 days. Patients were evaluated for complications during the follow-up period, which ranged from 1 to 18 months. Six patients (12.2 percent) experienced complications. These included infection (four patients), premature occlusal contact (one patient), and temporomandibular disorder (one patient). Except for one case, all complications were minor and adequately managed with incision and drainage, elastic traction, physical therapy, and medication. Delayed infection (osteomyelitis) developed in a symphysis fracture and was treated by saucerization and antibiotics. The fracture line subsequently showed complete consolidation. Bioabsorbable plates can be selectively used for internal fixation in mandibular fractures, with the advantage that they do not need to be removed.     

Pullout performance of self-tapping medical screws

This study investigates the effect of the pilot hole size, implant depth, synthetic bone density, and screw size on the pullout strength of the self-tapping screw using analytical, finite element, and experimental methodologies. Stress distribution and failure propagation mode around the implant thread zone are also investigated. Based on the finite element analysis (FEA) results, an analytical model for the pullout strength of the self-tapping screw is constructed in terms of the (synthetic) bone mechanical properties, screw size, and the implant depth. The pullout performance of self-tapping screws is discussed. Results from the analytical and finite element models are experimentally validated.     

Experimental and clinical results of new advances in the treatment of facial trauma

Theoretical considerations and photoelastic and mechanical experiments showed us the progression from metal wires to metal plates in different systems. In the midface there is no question about stabilization by miniplate systems. For mandibular fracture treatment, there is a discussion going on at present about the use of stable maxisystems versus less stable minisystems. Our clinical experience of 15 years indicates that there is no further demand for strict stable fixation of mandibular fractures, and we were encouraged to use less stable systems with similar good results, as our follow-up and statistical evaluation showed. To continue the simplification of osteosynthesis methods we are performing experiments with resorbable materials. Early results show fracture healing comparable with that found with plate-and-screw systems. Our clinical experience has shown that there is no longer any question about the ability of stable fracture treatment by means of osteosynthesis. However, there still is the question of how functional such fracture treatment might be.     

Aesthetic augmentation of the malar-midface structures

Based on extensive experience with bone grafts for augmentation of the midface-malar region, an implant design has been developed using Proplast. After careful preoperative assessment, a very specific surgical method, described herein, allows precise implant positioning without the need for suture fixation. In many instances, the 6-mm implant can be inserted unchanged. One-hundred and six patients have been operated on using 176 implants over the past 6 years. There were four unilateral infections (2.3 percent of implants and 3.8 percent of patients). None had permanent motor or sensory nerve problems. Fifteen implants (8.5 percent) in 12 patients (11.3 percent) were either removed or repositioned. In those having augmentation for entirely aesthetic reasons, 3 of 60 patients (5.0 percent) required implant removal or repositioning. The incidence of needing to remove or reposition implants has decreased as the technique has evolved.     

Anterior vertebral body screw pullout testing with the hollow modular anchorage system--a comparative in vitro study.

Pullout of implants at the proximal and distal ends of multilevel constructs represents a common spinal surgery problem. One goal concerning the development of new spinal implants is to achieve stable fixation together with the least invasive approach to the spinal column. This biomechanical study measures the influence of different modes of implantation and different screw designs, including a new monocortical system, on the maximum pullout strength of screws inserted ventrolaterally into calf vertebrae. The force pullout of eight different groups were tested and compared. Included were three bicortical used single screws (USS, Zielke-VDS, single KASS). To further increase pullout strength either a second screw (KASS) or a pullout-resistant nut can be added (USS with pullout nut). A completely new concept of anchorage represents the Hollow Modular Anchorage System (MACS-HMA). This hollow titanium implant has an increased outside diameter and is designed for monocortical use. Additionally two screw systems suitable for bicortical use were tested in monocortical mode of anchorage (USS, single KASS). We selected seven vertebrae equal in mean size and bone mineral density for each of the eight groups. The vertebral body and implant were connected to both ends of a servohydraulic testing machine. Displacement controlled distraction was applied until failure at the metal-bone-interface occurred. The maximum axial pullout force was recorded. Mean BMD was 312 +/- 55 mg CaHA/ml in cancellous bone and 498 +/- 98 mg CaHA/ml in cortical bone. The highest resistance to pullout found, measured 4.2 kN (KASS) and 4.0 kN (USS with pullout nut). The mean pullout strength of Zielke-VDS was 2.1 kN, of single KASS 2.5 kN, of MACS-HMA 2.6 kN and of USS 3.2 kN. There was no statistically significant difference (t-test, p > 0.05) between bicortical screws and the new monocortical implant. For the strongest fixation at the proximal or distal end of long spinal constructs the addition of a second screw or a pullout-resistant nut behind the opposite cortex offers even stronger fixation.     

新型迭形接骨板的临床应用

目的：改进骨折接骨扳内固定技术．观察新型迭形接骨板临床效果。方法：选择四肢长管骨骨折患者165例(上肢骨折26例,下肢骨折139例),均采用新型迭形接骨板施行骨折内固定手术。结果：手术后平均随访1年4个月(5年7个月～51天),除5例(占3％)出现并发症外,其余骨折均愈合良好,很少发现接骨板和螺钉断裂、折弯和松动情况。结论：与传统接骨板比较,新型迭形接骨板结构设计新颖,力学原理独特,临床效果满意,并发症少,较好地改进了四肢长管骨(尤其是下肢)骨折接骨板内固定技术,值得推荐。     

Cranial reossification with absorbable plates

The purpose of this study was to examine the effect of Lactosorb absorbable plates on bone healing across cranial bone defects in the rabbit skull. Two 10-mm diameter parietal skull defects were created in each of 20 rabbits, with one defect being placed on either side of the sagittal suture. In 10 rabbits, an absorbable plate was placed across both the inner and outer cortices of the left defect, and in the other 10 rabbits, an absorbable plate was placed across the outer cortex only of the left defect. The right defect always served as the control side, with no plate being placed across it. Rabbits were killed an average of 25 weeks postoperatively. Areas of reossification in the experimental and control defects of each rabbit were then measured, examined histologically, and compared. Growth across defects spanned by one plate was also compared with growth across defects spanned by two plates. Histologic and statistical analyses revealed no significant differences in reossification between the control and experimental defects in each animal and between the defects spanned by one versus two plates. This study suggests that these copolymer absorbable plates neither inhibit nor facilitate reossification across 10-mm diameter rabbit cranial defects.     

不同颌间牵引结合可吸收内固定材料在下颌骨骨折的重建研究

目的:下颌骨骨折患者采用可吸收内固定材料进行固定,同时结合牙弓夹板或自攻钛钉进行术后颌间牵引固定,探讨两种牵引方式对患者口腔情况和术后咬合关系恢复的促进作用。方法:对65例下颌骨骨折病例在完成骨折坚固内固定的基础上分别应用牙弓夹板和自攻钛钉进行颌间牵引,14 d后拆除颌间牵引,术后3-6月进行复查,对患者术后及复查期间口腔情况和咬合关系进行评估,采用两组间t检验进行统计学分析。结果:所有35例患者伤口均一期愈合。两种技术相结合,即使全面部骨折和陈旧性骨折都获得了良好的疗效,不同颌间牵引结果显示采用自攻钛钉治疗更加简便,口腔卫生情况明显好于采用牙弓夹板的患者;复查显示两组患者咬合关系恢复理想,两者骨折愈合、张口度及咬合关系无明显差异。结论:采用可吸收材料进行颌骨固位是一种较先进的坚固内固定方法,颌间自攻钛钉是恢复及维持咬合关系较为理想的治疗方法,两者结合可以获得满意的效果,值得临床推广。     

The use of Champy miniplates for osteosynthesis in craniofacial deformities and trauma

Champy miniplates have been used in the treatment of craniofacial fractures and in osteotomies for correction of posttraumatic deformities, congenital craniofacial deformities, and secondary bony deformities due to pathologies such as hemangioma and neurofibroma. An additional use has been to stabilize free and vascularized bone grafts. The total number of cases reviewed were 50 (25 acute trauma, 4 vascularized mandible reconstruction, and 21 osteotomies of varied types). There were three infections, two in mandibular fractures that were comminuted and compound into the mouth and one in a compound comminuted fracture of the frontal and maxillary area that was judged to be infected when the plate was placed in position. Two plates have been obvious under the skin. No patient has requested plate removal. The advantages of plating in selected cases are decreased operating time, rigid fixation at surgery, good fixation of bone grafts, and the ability to remove intermaxillary fixation in children at the end of the procedure or within the first few postoperative days.     

后路减压椎弓根螺钉内固定治疗胸腰椎骨折疗效分析

目的:探讨后路减压椎弓根螺钉内固定治疗胸腰椎骨折的疗效。方法:本研究选取了90例胸腰椎骨折患者,按照入院时间顺序不同分为两组,前路组(46例)采取前路减压椎弓根螺钉内固定治疗,后路组(44例)采取后路减压椎弓根螺钉内固定治疗。观察并记录两组患者围手术期参数,术前术后下腰痛功能、神经功能恢复情况及随访12个月期间并发症发生情况,评价后路减压椎弓根螺钉内固定治疗胸腰椎骨折的疗效。结果:后路组在术中失血量、手术时间、住院时间上均明显少于或短于前路组(P0.05);与术前相比,术后两组Oswestry功能障碍指数(ODI)值均明显降低(P0.05)。与术后同时间前路组相比,后路组ODI值均明显低于前路组(P0.05);与术前相比,术后12个月两组神经功能分级整体有所提高(P0.05),但两组间相比,差异没有统计学意义(P0.05);随访12个月期间,两组并发症发生率比较,差异没有统计学意义(P0.05)。结论:采用后路椎弓根螺钉内固定治疗胸腰椎骨折,手术时间短,疗效显著,术中出血量少,预后较好,有利于患者腰椎功能的恢复。     

Effect of bioabsorbable osseous fixation materials on dura mater and brain tissue

Bioabsorbable materials are frequently used in pediatric cranial surgery, but the effects of these materials on neural tissue are not known. The authors assessed the histologic alterations to dura mater and brain tissue associated with bioabsorbable plates. Fifteen Sprague-Dawley rats were given sham cranial surgery; an additional 30 underwent placement of 8 x 8-mm polylactic acid/poly-glycolic acid plates. The rats were assessed weekly for neurologic or behavioral changes suggesting neural damage. A portion of each group was killed at 3, 6, and 12 months for histologic analysis of cranium, dura mater, and brain tissue by standard hematoxylin and eosin stain. None of the animals showed any behavioral changes or neurologic deficits. The plates were gradually hydrolyzed over the study period, and all had disappeared by 12 months. The histologic examination showed fibrous encapsulation around the plates, accompanied by foreign body giant cell reaction and calcification. Focal gliosis, where evident, was mild and confined primarily to the superficial cortex of the brain beneath the plate. The infiltration of the dura mater and underlying brain parenchyma was negligible. In conclusion, the neurologic and histologic effect of bioabsorbable plates on neural tissue may be considered negligible in the early postoperative period.     

Comparative endurance testing of the Biomet Matthews Nail and the Dynamic Compression Screw,in simulated condylar and supracondylar femoral fractures

Background  

The dynamic compression screw is a plate and screws implant used to treat fractures of the distal femur. The Biomet Matthews Nail is a new retrograde intramedullary nail designed as an alternative surgical option to treat these fractures. The objective of this study was to assess the comparative endurance of both devices.     

重建钛板及记忆合金内固定治疗不稳定型骨盆骨折的效果

目的:探讨重建钛板及记忆合金内固定系统治疗不稳定型骨盆骨折的临床效果。方法:回顾性分析本院2012年12月~2013年12月收治的93例不稳定型骨盆骨折患者的临床资料,按照治疗方法分为两组,分别实施重建钛板联合螺钉固定治疗(对照组)和重建钛板联合记忆合金内固定系统治疗(观察组),观察并比较两组患者的临床效果。结果:观察组治疗优良率显著高于对照组,骨折愈合时间显著短于对照组,内固定松动和内固定断裂发生率显著低于对照组,差异均具有统计学意义(P0.05)。结论:重建钛板及记忆合金内固定系统治疗不稳定型骨盆骨折患者行可以获得较重建钛板联合螺钉固定治疗更好的临床效果。     

锁定板微创技术治疗老年人股骨远端骨折的临床效果观察

目的:探讨锁定板MIPO技术治疗老年人股骨远端骨折的临床效果。方法:回顾性分析2009年1月-2012年12月运用锁定板MIPO技术治疗老年人股骨远端骨折患者的临床资料,评估骨折类型、骨折愈合时间、6个月时的膝关节活动度和膝关节功能评分及临床并发症的发生情况。结果:共纳入33例老年人股骨远端骨折患者,平均年龄72岁,其中2例随访失败。87%的股骨远端骨折是关节外骨折;骨折平均愈合时间为12.56(8~29)周;术后6个月时平均活动范围超过105°:伸0°~30°,屈90°~140°;术后6个月的平均膝功能评分89.5;治疗过程中无植入失败、骨折不愈合和感染发生;术后早期发生下肢深静脉血栓(DVT)7例(22.6%),均在膝关节水平以下。结论:锁定板结合MIPO技术是一种治疗老年人股骨远端骨折安全有效的方法,但要注意预防术后DVT的发生。     

Cortical bone failure mechanisms during screw pullout

An experimental and computational study of screw pullout from cortical bone has been conducted. A novel modification of standard pullout tests providing real time image capture of damage mechanisms during screw pullout was developed. Pullout forces, measured using the novel test rig, have been validated against standard pullout tests. Pullout tests were conducted, considering osteon alignment, to investigate the effect of osteons aligned parallel to the axis of the orthopaedic screw (longitudinal pullout) as well as the effect of osteons aligned perpendicular to the axis of the screw (transverse pullout). Distinctive alternate failure mechanisms, for longitudinally and transversely orientated cortical bone during screw pullout, were uncovered. Vertical crack propagation, parallel to the axis of the screw, was observed for a longitudinal pullout. Horizontal crack propagation, perpendicular to the axis of the screw, was observed for a transverse pullout. Finite element simulation of screw pullout, incorporating material damage and crack propagation, was also performed. Simulations revealed that a homogenous material model for cortical bone predicts vertical crack propagation patterns for both longitudinal and transverse screw pullout. A bi-layered composite model representing cortical bone microstructure was developed. A unique set of material and damage properties was used for both transverse and longitudinal pullout simulations, with only layer orientations being changed. Simulations predicted: (i) higher pullout forces for transverse pullout; (ii) horizontal crack paths perpendicular to screw axis for transverse pullout, whereas vertical crack paths were computed for longitudinal pullout. Computed results agreed closely with experimental observations in terms of pullout force and crack propagation.