The critical size bony defect in a small animal for bone healing studies (II): implant evolution and surgical technique on a rat's femur.

In the preclinical field of orthopaedic and trauma surgery critical size bony defects (CDS) were used to evaluate the biocompatibility and allow to investigate the osteoinductivity and -conductivity of bone substitutes. Concerning the anatomical size the laboratory rat indicates a lower limit in small animals which are appropriate for experiments on bone. The aim of this study was to define a CSD, to develop a suitable fixation system to stabilize bony fragments in CSD and to point out the specialities of the surgical technique. These informations should help for to design and practice studies concerning bone healing on rat's femur. Based on previously acquired anatomical data of rat's femur, the technical challenges and anatomical specialities of different osteosynthesis techniques in rat's femur surgery are demonstrated. Our experiences with different fixation systems and techniques lead to the development of an external fixator, which guarantees for a stable bone fragment fixation, prevents severe soft tissue damage, allows of a roentgenologic evaluation of the defect zone and prevents from undesired direct biomaterial-implant interactions. Neither the proximal nor the distal femoral nailing technique is appropriate for a stable fixation in CSD of rat's femur. To evaluate the reliability of an own developed external fixator 42 nude rats with a 4.0 mm CSD were investigated clinically and roentgenologically over 10 weeks. The external fixator showed only a small implant failure rate. A solid fusion of the bone fragments was not observed within the 10 weeks follow-up period.     

骨质疏松性脊柱内固定技术进展

骨质疏松症是一种以骨量减少,骨强度下降而脆性增加,骨折风险增加为特征的骨骼疾病。随着人口老龄化日趋严重,骨质疏松症已成为我国面临的重要公共健康问题。这些患者往往并存多种疾病,其中椎体骨折最为突出,危害较大。由于此类患者的虚弱的体质和较低的骨密度,实施手术治疗十分困难。新型的手术方式的开发和内固定植入物的设计明显降低了内固定失败率,提升了内固定稳定性。这些技术综合考虑了生物材料学、生物学和生物力学等多方面,在临床应用上获得了较好的疗效。本综述旨在总结脊柱内固定失败的机制和现存的新型手术技术与内固定植入物设计,并对未来脊柱内固定手术的发展方向加以展望。     

Mandibular reconstruction with the titanium hollow screw reconstruction plate (THORP) system: evaluation of 62 cases

The titanium hollow screw reconstruction plate (THORP) system for reconstruction of lower jaw defects provides a functional stable fixation and is used as a long-term or permanent implant in tumor surgery and in traumatology. The rigid fixation of the head of the screw to the plate, avoiding unphysiologic loads to the bone underneath the plate, and the titanium plasma-coated perforated hollow screws, enabling the development of direct bone-titanium contact as well as the ingrowth of bone into the lumen and perforations, are the major advantages of this system compared to conventional systems. The different surgical methods, such as preservation of the condylar process with only two screws, intraoperative freely adjustable condylar prosthesis, lingual application of the plate, and primary bone transplantation, are described. The evaluation of 62 patients reconstructed with the THORP system between 1981 and 1986 revealed no plate loosening, even in irradiated bone, and showed satisfactory aesthetic and functional results.     

Body dysmorphic disorder: diagnosis and approach

Body dysmorphic disorder is a psychiatric disease that can be frequently encountered in an aesthetic practice. Body dysmorphic disorder is characterized by a preoccupation with a minimal or nonexistent appearance defect and causes significant distress and interferes with the social life of the patient. The perceived physical anomaly may involve the shape and size of the whole body or may be centered around single units. Body dysmorphic disorder patients are known to request multiple aesthetic procedures that leave them unsatisfied. Only a timely diagnosis will enable the surgeon and staff to adequately address the patient's needs. Body dysmorphic disorder patients cannot be cured with surgery. Diagnostic techniques such as patient interview and observation are presented in this article. With this, the plastic surgeon should be able to diagnose body dysmorphic disorder preoperatively. Using the presented algorithm to approach body dysmorphic disorder patients will avoid disappointment for patients and surgeons alike.     

Midface fractures: advantages of immediate extended open reduction and bone grafting

Experience with 240 midface (Le Fort and zygoma) fractures in multiple trauma patients has emphasized that superior aesthetic results are obtained by immediate extended open reduction with primary bone grafting. Internal fixation of 110 zygomatic and 130 Le Fort fractures was performed in the lower midface (zygomaticomaxillary and nasomaxillary buttresses). Open reduction of the condyle was employed in five concomitant Le Fort and subcondylar fractures with a loss of ramus height to prevent superior and posterior displacement of the middle and lower face. Bone grafts were utilized in 74 patients. They were most frequently employed in the orbit and less frequently in the lower midface. Bone graft survival paralleled that observed under elective conditions, and a slightly higher infection rate was observed. Extended open reduction and immediate bone grafting adds a new dimension to the aesthetic results obtained from facial fracture treatment. Structural bony integrity and pre-injury facial architecture may be restored in the absence of soft-tissue contracture. Restoration of the pre-injury facial architecture (the essence of facial fracture treatment) is more accurately accomplished when these techniques are utilized.     

Aesthetic improvements in free-flap mandible reconstruction

Mandible reconstruction with free flaps has become a well-established technique. Efforts are now focused on obtaining superior functional and aesthetic results. Improvements in the quality of the latter are possible with a systematic approach to shaping the bone graft. Important elements in this approach have been defined based on experience in 50 consecutive cases. Preoperative studies include the lateral cephalogram and a transverse plane CT scan from which mandible templates are constructed. These templates are models of the mandible in two planes and are used to shape the bone with a high degree of precision. They allow the bone to be completely shaped while still attached by the pedicle at the donor site. The surgical specimen serves as an additional key visual reference and as a source of measurements to determine overall bone-graft length. Miniplates alone provide sufficient fixation to stabilize the bone as it is shaped segment by segment. Intermaxillary fixation is used only to prevent errors in total bone-graft length. Hemimandible and anterior defects represent two completely different bone-shaping problems. Although the bone-shaping methods described have been developed primarily with the fibula, they have been successfully applied to the scapula and radius donor sites as well.     

Numerical simulations of bone remodelling and formation following nucleotomy

Nucleotomy is the gold standard treatment for disc herniation and has proven ability to restore stability by creating a bony bridge without any additional fixation. However, the evolution of mineral density in the extant and new bone after nucleotomy and fixation techniques has to date not been investigated in detail. The main goal of this study is to determine possible mechanisms that may trigger the bone remodelling and formation processes.With that purpose, a finite element model of the L4–L5 spinal segment was used. Bone mineral density (BMD), new tissue composition, and endplate deflection were determined as indicators of lumbar fusion. A bone-remodelling algorithm and a tissue-healing algorithm, both mechanically driven, were implemented to predict vertebral bone alterations and fusion patterns after nucleotomy, internal fixation, and anterior plate placement.When considering an intact disc height, neither nucleotomy nor internal fixation were able to provide the necessary stability to promote bony fusion. However, when 75% of the disc height was considered, bone fusion was predicted for both techniques. By contrast, an anterior plate allowed bone fusion at all disc heights. A 50% disc-height reduction led to osteophyte formation in all cases. Changes in the intervertebral disc tissue caused BMD alterations in the endplates.From this observations it can be drawn that fusion may be self-induced by controlling the mechanical stabilisation without the need of additional fixation. The amount of tissue to be removed to achieve this stabilisation remains to be determined.     

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

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

An approximate model for cancellous bone screw fixation

This paper presents a finite element (FE) model to identify parameters that affect the performance of an improved cancellous bone screw fixation technique, and hence potentially improve fracture treatment. In cancellous bone of low apparent density, it can be difficult to achieve adequate screw fixation and hence provide stable fracture fixation that enables bone healing. Data from predictive FE models indicate that cements can have a significant potential to improve screw holding power in cancellous bone. These FE models are used to demonstrate the key parameters that determine pull-out strength in a variety of screw, bone and cement set-ups, and to compare the effectiveness of different configurations. The paper concludes that significant advantages, up to an order of magnitude, in screw pull-out strength in cancellous bone might be gained by the appropriate use of a currently approved calcium phosphate cement.     

The role of primary bone grafting in complex craniomaxillofacial trauma

The role of craniofacial surgical techniques and immediate bone grafting in the management of complex craniofacial trauma has been reviewed. Four hundred and one patients with complex facial injuries have been treated. Two hundred and forty-one primary bone and cartilage grafts have been performed in 66 patients. Complex facial injuries should be managed by direct exposure, reduction, and fixation of all fractures utilizing interfragmentary wiring. Very comminuted or absent bone is replaced by immediate bone grafting, producing a stable skeleton without the need for external fixation devices. Associated mandibular fractures are managed with rigid internal fixation utilizing A-O technique. Results of immediate bone grafting have been excellent, and complications are rare. All deformities should be corrected, whenever possible, during the initial operation. This one-stage reconstruction of even the most complex facial injuries will prevent severe postoperative traumatic deformity and disability that may be extremely difficult or impossible to correct secondarily.     

Fixation effects on membranous and endochondral onlay bone graft revascularization and bone deposition.

This paper investigates the relationship between bone resorption, the process of bone revascularization, and graft fixation. Vital staining techniques and microangiography were used to study the extent of graft revascularization of fixed and nonfixed endochondral (rib) and membranous (skull) onlay bone grafts in 20 adult sheep mandibles bilaterally. This assessment was carried out at 2 and 20 weeks postoperatively. Sequential fluorochrome staining was performed to examine the pattern of new bone deposition. Fixation was achieved using the lagscrew technique. At 2 weeks, membranous bone demonstrated a greater area of graft revascularization if fixed than if the graft was not fixed. The opposite result was seen for endochondral grafts, where nonfixed grafts showed a greater area of revascularization than fixed grafts. At 20 weeks, all bone that was present was fully vascularized. The inconsistencies in the results on the relationship between fixation and revascularization for membranous and endochondral grafts in the early stages of healing (2 weeks) suggest that although revascularization is a necessary precondition for bone resorption and deposition, biomechanical and structural factors may be a more satisfactory explanation for the differences observed in the maintenance of bony volume.     

The influence of tibial component fixation techniques on resorption of supporting bone stock after total knee replacement

Periprosthetic bone resorption after tibial prosthesis implantation remains a concern for long-term fixation performance. The fixation techniques may inherently aggravate the "stress-shielding" effect of the implant, leading to weakened bone foundation. In this study, two cemented tibial fixation cases (fully cemented and hybrid cementing with cement applied under the tibial tray leaving the stem uncemented) and three cementless cases relying on bony ingrowth (no, partial and fully ingrown) were modelled using the finite element method with a strain-adaptive remodelling theory incorporated to predict the change in the bone apparent density after prosthesis implantation. When the models were loaded with physiological knee joint loads, the predicted patterns of bone resorption correlated well with reported densitometry results. The modelling results showed that the firm anchorage fixation formed between the prosthesis and the bone for the fully cemented and fully ingrown cases greatly increased the amount of proximal bone resorption. Bone resorption in tibial fixations with a less secure anchorage (hybrid cementing, partial and no ingrowth) occurred at almost half the rate of the changes around the fixations with a firm anchorage. The results suggested that the hybrid cementing fixation or the cementless fixation with partial bony ingrowth (into the porous-coated prosthesis surface) is preferred for preserving proximal tibial bone stock, which should help to maintain post-operative fixation stability. Specifically, the hybrid cementing fixation induced the least amount of bone resorption.     

Reconstruction of mandibular and floor of mouth defects using the trapezius osteomyocutaneous flap

The trapezius osteomyocutaneous island flap has evolved in postablative head and neck reconstruction as a versatile and hardy local flap which can provide intraoral lining, well-vascularized bone, and muscle bulk for the reconstruction of a complex defect. This investigative study examines the anatomy of 20 osteomyocutaneous flaps in 10 fresh cadavers and in 8 clinical patients. In our series, 80 percent (type I) of the major vascular pedicle arose from the thyrocervical trunk. In 20 percent (type II), the major pedicle arose separately from the subclavian artery. The regions perfused by the vascular trunk were further examined with microopaque and Prussian blue injections through the transverse cervical artery. Consistent areas of cutaneous staining as well as bony staining were noted over the shoulder, arm, and back and into the scapula itself. Experience with eight clinical applications of this osteomyocutaneous flap resulted in successful healing with an excellent aesthetic and functional result. Long-term follow-up was maintained on the patients for up to 36 months. Panorex radiographs and biopsies of the grafted bone were obtained on several patients. These disclosed evidence of bony remodeling and viable bone tissue. Tetracycline labeling also revealed evidence of active bony turnover.     

Aesthetic and restorative midface lifting with hand-carved,expanded polytetrafluoroethylene orbital rim implants

The midface lift represents an important advance in aesthetic and reconstructive surgery. However, the need for reliable fixation along the orbital rim has been a significant challenge. Furthermore, volume is needed at the orbital rim, to compensate for long-term remodeling of the bone of the orbital rim and malar face. A technique using a hand-carved, expanded polytetrafluoroethylene implant that is permanently anchored to the orbital rim with titanium microscrews, creating a site for fixation of the advanced midface soft tissues, was developed. This report presents a retrospective, uncontrolled, case series of 41 consecutive patients who underwent transconjunctival midface operations with these implants, and it addresses a variety of midface aesthetic and reconstructive deficits. Only patients with at least 6 months of follow-up data were included in the study. To date, significant complications have been limited. The complications included two cases of implant palpability, with only one requiring surgical modification. One patient underwent implant removal because of skin breakdown and infection related to recurrent squamous cell carcinoma. One patient required revisional lateral canthoplasty for reasons of symmetry. On the basis of this series, hand-carved, expanded polytetrafluoroethylene implants seem to have significant advantages, compared with previously available orbital rim implants. These advantages include the ability to easily modify the implant for the individual anatomical needs, the creation of a secure anchor for fixation of advanced midface soft tissues, excellent tolerance of the implant material, and the ability to place the implant with limited exposure. The greatest disadvantage is the need for the surgeon to carve the implant, which requires time and carving skill. Despite this limitation, the technique is promising.     

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.     

Surgical correction of the nose and midface in maxillonasal dysplasia (Binder's syndrome)

In 48 patients with maxillonasal dysplasia the retruded nasal base was corrected with onlay cancellous bone grafts after subperiosteal dissection using an oral vestibular approach. Support for the nasal dorsum was achieved in 39 patients with an L-shaped bone graft from the iliac crest introduced through the same approach. The advancement of the nose was found stable on lateral cephalograms; i.e., resorption did not occur. However, the grafts showed considerable remodeling. Half the patients found the stiffness of the nose to be disturbing. In nine patients, the cartilaginous septum was used instead as a support for the nasal dorsum and tip. At operation, the entire cartilaginous septum was mobilized after subperichondrial dissection and rotated forward either pedicled at the nasal dorsum or completely released. Cartilage regenerated in the periochondrial pocket left behind the advanced septum. The anterior transfer of the nose was 6 to 10 mm. The use of septal advancement is preferred over bone implants in the correction of maxillonasal dysplasia in patients in whom the bony nasal dorsum is of adequate height because it results in a soft and flexible nose and the risk of traumatic fracture and resorption is eliminated. The technique has been used in adolescents with promising results.     

A histologic evaluation of fracture repair in the midface

Although much has been written regarding the treatment of facial bone fractures, at the present time there are no available investigations of human microscopic sections to verify the exact nature of the healing process. The consensus in the literature is that following fractures of the midface, the bone segments are united by fibrous union. Biopsies of the healed fracture sites were obtained in 10 consecutive patients who underwent secondary reconstructive procedures to correct residual deformities. Clinical assessment confirmed that the fractures were completely healed and stable. Histologic sections were obtained across the healed fracture sites, sent for H&E staining, and then examined by light microscopy. All specimens showed that the defects between the segments were obliterated by the formation of a mature compact bone. This bridging bone was characterized by concentric lamellae surrounded by a typical bony architecture. From this study it can be concluded that fractures of the midface heal by direct bony union.     

A technique for the quantification of the 3D connectivity of thin articulations in Bony sutures

The anatomy and development of cranial and facial sutures have been studied in detail using histological sections, 2D radiographs and more recently CT imaging. However, little attention has been paid to evaluating and quantifying the connectivity of these thin cortical bone articulations. More recent technological advances such as micro-CT imaging has the potential to be used to provide quantitative measurements of 3D connectivity in bony articulations. This study presents a new technique for quantifying the connectivity of bony projections inside cranial and facial sutures using a combination of skeletonization, thinning algorithms and 3D intensity mapping. The technique is demonstrated in five sutures through semi-automated analysis and image processing of μCT scans. In the sagittal, coronal and frontozygomatic sutures an average bone connectivity of 6.6–11.6% was found with multiple bony projections providing an interlocking structure between adjacent bones. Much higher bone connectivity was present in the zygomaticotemporal and zygomaticomaxillary sutures (22.7–37.4%) with few bony projections. This method combining μCT scanning and image processing techniques was successfully used to quantify the connectivity of thin bone articulations and allowed detailed assessment of sutural fusion in 3D. The wider application of this technique may allow quantification of connectivity in other structures, in particular fracture healing of long bones.     

The vascularized pig fibula bone flap model: effects of multiple segmental osteotomies on growth and viability

Previous work by this laboratory introduced the pig fibula bone flap as a model for the study of the pathophysiology of vascularized bone flaps. Anatomic and hemodynamic studies demonstrated a significant (p < 0.05) decrease in vascular perfusion after a series of segmental osteotomies and rigid fixation (lag screws and miniplates) in the distal end of the flap, suggesting that blood flow to the distal osteotomized segment of the flap may be impaired. Killing the animals after blood flow studies precluded assessment of the effect of these hemodynamic changes on bone healing. Therefore, the aim of this study was to assess the pig fibula bone flap model with respect to viability, healing, and subsequent growth after multiple segmental osteotomies and rigid fixation to contribute to the understanding of vascularized bone flap pathophysiology. Yorkshire pigs (20 to 25 kg) were used for all experiments. Eight pigs underwent unilateral elevation of a vascularized fibula bone flap, which was osteotomized into three segments and orthotopically rigidly fixed using a 2.4-mm mandibular reconstruction plate. The left fibula remained as the control. Fluorochrome labels were injected to assess bone viability and turnover, and both fibulae were assessed for growth radiologically. The fibulae were harvested 21 days postoperatively (when the animals were killed), and bone healing was assessed histologically and clinically. There were no significant differences in preoperative and postoperative lengths of the osteotomized fibulae compared with the controls, suggesting that there was no impairment of growth potential after multiple segmental osteotomies and rigid fixation. Significant (p < 0.05) bony hypertrophy of the osteotomized fibulae was noted when compared with controls. Mobility was observed in 3 of the 32 osteotomies (9 percent), occurring across one proximal and two distal osteotomies in association with failure of fixation. However, histologic and fluorochrome assessment confirmed the viability of all bone segments, as supported by the presence of tetracycline given 2 days postoperatively. The pig fibula bone flap model is well tolerated by the pig. Multiple segmental osteotomies and rigid fixation, previously associated with a significant decrease in blood flow in the distal segment, did not impair either growth potential, viability, or healing ability. It is suggested that the pig fibula is a suitable model for the study of bone flap pathophysiology.     

Vascularized rib for facial reconstruction

The reconstruction of maxillectomy defects is a complex problem encountered in plastic surgery. Defects can range in size and complexity from small defects requiring only soft tissue to complete maxillectomies requiring large tissue bulk, bone, and one or more skin paddles. The most difficult defects involve the skull base and orbit. The reconstructive surgeon is faced with the challenge of isolating the nasopharynx from the dura and globe while simultaneously restoring the bony framework of the maxilla and orbit to support the soft tissue of the cheek. The authors present a series of six reconstructions using a rectus abdominis muscle flap with associated vascularized rib for reconstruction of complex maxillectomy defects. This flap provides large soft-tissue bulk as well as bony support and a long vascular pedicle. A skin island can be taken with the flap, and the donor-site morbidity is comparable to that seen with a vertical rectus abdominis myocutaneous flap. Six flaps were used in five patients over a 20-month period. All patients had stable support of the orbit at follow-up with adequate soft-tissue coverage, and there were no incidences of visual changes.