Rigid Implants Research Articles

Management of Extradural Dead Space During Cranioplasty—A Scoping Review

Background: Cranioplasty after craniectomy restores cerebral spinal fluid (CSF) flow dynamics, protects the brain from trauma, and restores skull contour. However, post-cranioplasty extradural dead space may persist, leading to infection and necessitating further surgical interventions. The purpose of this scoping review was to identify and analyze the existing peer-reviewed literature discussing the management of extra-dural dead space during cranioplasty. Methods: A systematic review of the literature was performed via searches of Embase, Cochrane, and PubMed in accordance with PRISMA guidelines. Included studies focused on managing extradural dead space in supratentorial cranioplasty using rigid implants or autologous bone. Studies solely using soft tissue repairs or non-primary studies were excluded. Data extraction covered study characteristics, management techniques, complications, and patient outcomes. Results: Out of 2196 articles, 135 underwent full-text review, and 28 were included, discussing 117 patients. Indications for dead space management included intractable infection (86%), syndrome of the trephined (25%), high-volume dead space (18%), persistent CSF leak (18%), and scarred dura (7%). Management techniques included muscle flaps (46%), omental flaps (14%), fat grafts (7%), and placement of non-organic materials (11%). Complications occurred in 32% of studies, including flap failure, hematoma, and CSF leak. Muscle flaps had a 22% complication rate but led to a high rate of infection resolution (97%). Conclusions: Managing extradural dead space with vascularized flaps during cranioplasty can reduce infection risk but may be associated with high complication rates. The lack of standardized practices and limited high-quality studies highlight the need for further research to establish the safety, efficacy, and best patient selection criteria for these techniques.

Debulking of the Femoral Stem in a Primary Total Hip Joint Replacement: A Novel Method to Reduce Stress Shielding.

In current-generation designs of total primary hip joint replacement, the prostheses are fabricated from alloys. The modulus of elasticity of the alloy is substantially higher than that of the surrounding bone. This discrepancy plays a role in a phenomenon known as stress shielding, in which the bone bears a reduced proportion of the applied load. Stress shielding has been implicated in aseptic loosening of the implant which, in turn, results in reduction in the in vivo life of the implant. Rigid implants shield surrounding bone from mechanical loading, and the reduction in skeletal stress necessary to maintain bone mass and density results in accelerated bone loss, the forerunner to implant loosening. Femoral stems of various geometries and surface modifications, materials and material distributions, and porous structures have been investigated to achieve mechanical properties of stems closer to those of bone to mitigate stress shielding. For improved load transfer from implant to femur, the proposed study investigated a strategic debulking effort to impart controlled flexibility while retaining sufficient strength and endurance properties. Using an iterative design process, debulked configurations based on an internal skeletal truss framework were evaluated using finite element analysis. The implant models analyzed were solid; hollow, with a proximal hollowed stem; FB-2A, with thin, curved trusses extending from the central spine; and FB-3B and FB-3C, with thick, flat trusses extending from the central spine in a balanced-truss and a hemi-truss configuration, respectively. As outlined in the International Organization for Standardization (ISO) 7206 standards, implants were offset in natural femur for evaluation of load distribution or potted in testing cylinders for fatigue testing. The commonality across all debulked designs was the minimization of proximal stress shielding compared to conventional solid implants. Stem topography can influence performance, and the truss implants with or without the calcar collar were evaluated. Load sharing was equally effective irrespective of the collar; however, the collar was critical to reducing the stresses in the implant. Whether bonded directly to bone or cemented in the femur, the truss stem was effective at limiting stress shielding. However, a localized increase in maximum principal stress at the proximal lateral junction could adversely affect cement integrity. The controlled accommodation of deformation of the implant wall contributes to the load sharing capability of the truss implant, and for a superior biomechanical performance, the collared stem should be implanted in interference fit. Considering the results of all implant designs, the truss implant model FB-3C was the best model.

Partial Ossicular Reconstruction With a Novel Ball Joint Prosthesis: The mCLIP ARC Partial Prosthesis.

Middle ear surgery involves reconstruction of the ossicular chain, predominately using rigid implants. New middle ear prostheses strive to mimic the physiologic micromovements of the ossicular chain and prevent dislocation, protrusion, and preloading of the annular ligament due to pressure fluctuations. Thirty-five patients were included in a monocentric, prospective observational study. Patients received tympanoplasty with ossicular reconstruction using the mCLIP ARC partial prosthesis. This titanium prosthesis is equipped with a clip mechanism for coupling at the stapes and a ball joint connecting headplate and shaft. At short-term (ST) and mid-term (MT) follow-up, pure-tone audiometry was performed and the pure tone average of 0.5, 1, 2, and 3 kHz (PTA4) was calculated. The audiological outcome was compared with retrospective data of the Dresden titanium clip prosthesis. The new prosthesis shows favorable clinical results. Pure-tone audiometry showed satisfactory results in ST and MT follow-up, with the PTA4 air-bone gap (ABG) decreasing from 24.5 (±11) dB to 17.4 (±7.9) dB at the ST follow-up at 27 days to 15.6 (±10.3) dB at MT follow-up at 196 days (n = 32). A PTA4-ABG value of less than 20 dB was achieved by 63% of patients at ST follow-up and by 77% at MT follow-up. There was no significant difference in PTA4 ABG compared to the Dresden titanium clip prosthesis during ST follow-up (p = 0.18). The mCLIP ARC partial prosthesis, a new middle ear prosthesis with a balanced ball joint, shows promising audiological results and is a safe and effective choice for patients with chronic ear disease. 3 Laryngoscope, 134:3323-3328, 2024.

Biodegradable, Biocompatible, and Implantable Multifunctional Sensing Platform for Cardiac Monitoring.

Cardiac monitoring after heart surgeries is crucial for health maintenance and detecting postoperative complications early. However, current methods like rigid implants have limitations, as they require performing second complex surgeries for removal, increasing infection and inflammation risks, thus prompting research for improved sensing monitoring technologies. Herein, we introduce a nanosensor platform that is biodegradable, biocompatible, and integrated with multifunctions, suitable for use as implants for cardiac monitoring. The device has two electrochemical biosensors for sensing lactic acid and pH as well as a pressure sensor and a chemiresistor array for detecting volatile organic compounds. Its biocompatibility with myocytes has been tested in vitro, and its biodegradability and sensing function have been proven with ex vivo experiments using a three-dimensional (3D)-printed heart model and 3D-printed cardiac tissue patches. Moreover, an artificial intelligence-based predictive model was designed to fuse sensor data for more precise health assessment, making it a suitable candidate for clinical use. This sensing platform promises impactful applications in the realm of cardiac patient care, laying the foundation for advanced life-saving developments.

Fabrication of 3D Printed, Core-and-Shell Implants as Controlled Release Systems for Local siRNA Delivery.

The development and clinical translation of small interfering RNA (siRNA) therapies remains challenging owing to their poor pharmacokinetics. 3D printing technology presents a great opportunity to fabricate personalized implants for local and sustained delivery of siRNA. Hydrogels can mimic the mechanical properties of tissues, avoiding the problems associated with rigid implants. Herein, a thermoresponsive composite hydrogel suitable for extrusion 3D-printing is formulated to fabricate controlled-release implants loaded with siRNA-Lipofectamine RNAiMAX complexes. A hydrogel matrix mainly composed of uncharged agarose to protect siRNA from decomplexation is selected. Additionally, pluronic F127 and gelatin are added to improve the printability, degradation, and cell adhesion to the implants. To avoid exposing siRNA to thermal stress during the printing process, a core-and-shell design is set up for the implants in which a core of siRNA-complexes loaded-pluronic F127 is printed without heat and enclosed with a shell comprising the thermoresponsive composite hydrogel. The release profile of siRNA-complexes is envisioned to be controlled by varying the printing patterns. The results reveal that the implants sustain siRNA release for one month. The intactness of the released siRNA-complexes is proven until the eighth day. Furthermore, by changing the printing patterns, the release profiles can be tailored.

A Partial Ossicular Replacement Prosthesis With a Concentric Ball Joint in the Headplate.

In passive middle ear prosthetics, rigid implants have proven successful in reconstructing the ossicular chain. However, these cannot fully replicate the physiology of the ossicular chain. Pressure fluctuations cause high stresses in rigid passive prostheses, which can result in dislocation, protrusion, and pre-tension in the annular ligament resulting in unsatisfactory hearing results. In collaboration with MED-EL, we developed a new passive middle ear prosthesis that features a balanced, centered ball joint between the headplate and shaft of the prosthesis. We compared the sound transmission properties of this new prosthesis with those of a standard rigid prosthesis. Using Laser-Doppler-Vibrometry, we measured the sound-induced velocity of the stapes footplate relative to a given acoustic stimulus. The new prosthesis showed equivalent sound transmission characteristics compared to the rigid prosthesis, whereas retaining the ability to compensate for pressure fluctuations due to its ball joint. This ensures good transmission properties even during displacements of the tympanic membrane. This development is a further step toward a physiological reconstruction of the ossicular chain. NA Laryngoscope, 133:1717-1721, 2023.

Nasoseptal flap and rigid reconstruction in endoscopic endonasal skull base surgeries: The longitudinal experience of a single center.

Recently, endoscopic endonasal approaches (EEA) have been used for skull base defect reconstruction surgeries. The nasoseptal flap (NSF), a vascular pedicled flap, was introduced to decrease postoperative cerebrospinal fluid (CSF) leakage. This study aimed to outline the authors' institutional experience using NSF and rigid implants in anterior skull base defect reconstruction surgeries following EEA. A retrospective cohort review of patients who underwent NSF reconstruction following EEA in the Otorhinolaryngology and Neurosurgery Departments at King Saud University Medical City, Riyadh, Saudi Arabia, from January 2015 to May 2021, divided into 2time periods according to the reconstruction technique. Out of the 106 patients who underwent EEA, 77 underwent NSF reconstruction. The majority had expanded EEA (94.8%). The mean age was 40.21 ± 17.7years, and the female gender represented 61% of the sample. More than half of the sample underwent right NSF (57.1%). Meningioma was the most common diagnosis (45.5%). The clivus was the most frequent site of lesions (23.4%). The overall rate of postoperative CSF leakage and lumbar drainage (LD) insertion was 15.6% and 51.9%, respectively. The duration of LD was a median of four days. The overall failure rate was 13%, declining from 20% in the first period to 5.4% in the second period. Rigid implants were used significantly more in the first period than in the second period (67.5% versus 16.2%, P < 0.001). Meningitis, the highest postoperative complication, was reported in 6 patients (7.8%). One patient died three weeks postoperatively after massive nasal bleeding. No significant difference was found between either side of the NFS regarding the CSF leakage and failure rate. In the authors' experience, there has been an overt decline in failure rates and complications of EEA over the last three years due to increased experience among surgeons and a standardization of reconstruction techniques. Minimal reconstruction may provide satisfactory results by decreasing the use of rigid implants. An endoscopic endonasal approach with an NSF for anterior skull base defect reconstruction is considered a safe procedure with no significant difference between the sides of the flap.

In silico evaluation of lattice designs for additively manufactured total hip implants

Additive manufacturing restructures the fabrication of custom medical implants and transforms the design, topology optimization, and material selection perspectives in biomechanical applications. Additionally, it facilitated the design and fabrication of patient-oriented hip implants. Selection of proper lattice type is critical in additive manufacturing of hip implants. The lattice types reduce the implant mass and, due to higher stress distribution and deformations as compared to the rigid implants, it brings down the stress shielding issues. This study introduces a rigid shell structure and infill lattice hip implant.Additionally, the effect of various lattice unit cell thickness (0.2–1 mm) and elemental size (2.5–5 mm) while applying 2300 N axial force is explored numerically. A cubic structure with two rigid surfaces on the top and bottom is outlined to separate the effect of the hip implant cross-sectional area variations. The stress distribution and deformation characteristics are validated with the hip implant design. The Finite Element Analysis (FEA) demonstrated that the Weaire-Phelan lattice structure exhibits the least stress and deformation among the other types at various design parameters. Additionally, the same methodology is applied to three biocompatible hip implant materials as Ti–6Al–4V, TA15 (Ti–6Al–2Zr–1Mo–1V), and CoCr28Mo6. Finally, the effect of the unit cell thickness and size on the implant's mass reduction considering the lattice's safety factor is investigated for the mentioned materials. The selection of a Weaire–Phelan lattice with the optimized safety factor and mass reduction is represented considering all the results. The optimized parameters for Titanium-based alloys are approximately 3.5 mm unit cell size with 0.6 mm beam thickness. However, the CoCr Mo-based alloy requires a thicker beam size (about 0.8 mm) due to lower safety factors.

Морфоскопическая и морфометрическая характеристики межпозвоночного диска LV-SI у лиц молодого и среднего возраста

Objective: to study the morphoscopic and morphometric characteristics of the LV-SI intervertebral disc according to magnetic resonance imaging. Materials and methods. The analysis of magnetic resonance imaging of 90 patients (66 men, 24 women) who did not have diseases of the lumbar spine was performed. Various morphometric parameters of the intervertebral disc (IVD) and nucleus pulposus (NP) at the LV-SI level were measured using software for processing images created on an MRI machine. The obtained data were compared between men and women, asthenics, normosthenics, hypersthenics and young (from 18 to 44 years old) and middle-aged (from 45 to 60 years old) people. In addition, morphoscopic characteristics were studied: the shape of the IVD and NP in the axial plane. Results. It was found that in normal IVD LV-SI is most often represented by elliptical (54,5%) less often kidney-shaped (45,5%) forms. Normally, the NP has an oval (57,8%) and kidney-shaped (42,2%) shape. It was shown that in men, the dorsal height of the IVD, its width, anteroposterior size, square as well as the longitudinal-transverse index of the NP were significantly higher. It has been proven that there are no significant differences in the shape of the IVD between asthenics, normo- and hypersthenics, while the height of the IVD in the center, its ventral, dorsal heights and most lateral IVD height are significantly greater in hypersthenics. It has been proved that the kidney-shaped form of NP was significantly more common in asthenics, and the oval form - in hypersthenics, while the morphometric parameters of NP did not significantly differ between extreme body types. A tendency to a decrease in IVD height in middle-aged people compared to young people was shown. Conclusion. The results obtained are necessary when planning the operation, as well as for the manufacture of rigid implants and artificial discs for arthroplasty and interbody fusion.

Expert consensus on resection of chest wall tumors and chest wall reconstruction

Chest wall tumors are a relatively uncommon disease in clinical practice. Most of the published studies about chest wall tumors are usually single-center retrospective studies, involving few patients. Therefore, evidences regarding clinical conclusions about chest wall tumors are lacking, and some controversial issues have still to be agreed upon. In January 2019, 73 experts in thoracic surgery, plastic surgery, science, and engineering jointly released the Chinese Expert Consensus on Chest Wall Tumor Resection and Chest Wall Reconstruction (2018 edition). After that, numerous experts put forward new perspectives on some academic issues in this version of the consensus, pointing out the necessity to further discuss the points of contention. Thus, we conducted a survey through the administration of a questionnaire among 85 experts in the world. Consensus has been reached on some major points as follows. (I) Wide excision should be performed for desmoid tumor (DT) of chest wall. After excluding the distant metastasis by multi-disciplinary team, solitary sternal plasmacytoma can be treated with extensive resection and adjuvant radiotherapy. (II) Wide excision with above 2 cm margin distance should be attempted to obtain R0 resection margin for chest wall tumor unless the tumor involves vital organs or structures, including the great vessels, heart, trachea, joints, and spine. (III) For patients with chest wall tumors undergoing unplanned excision (UE) for the first time, it is necessary to carry out wide excision as soon as possible within 1–3 months following the previous surgery. (IV) Current Tumor Node Metastasis staging criteria (American Joint Committee on Cancer) of bone tumor and soft tissue sarcoma are not suitable for chest wall sarcomas. (V) It is necessary to use rigid implants for chest wall reconstruction once the maximum diameter of the chest wall defect exceeds 5 cm in adults and adolescents. (VI) For non-small cell lung cancer (NSCLC) invading the chest wall, wide excision with neoadjuvant and/or adjuvant therapy are recommended for patients with stage T3-4N0-1M0. As clear guidelines are lacking, these consensus statements on controversial issues on chest wall tumors and resection could possibly serve as further guidance in clinical practice during the upcoming years.

Anti-adhesive membranes based on crosslinked carboxymethyl cellulose

In recent times, new anti-adhesion devices including devices based on carboxymethyl cellulose (CMC), which have “barrier” effect are being developed and actively introduced into surgical practice. The “barrier” should be completely resorbed after the time required to healing the morphofunctional integrity of the injured peritoneum, be economically available and easy to use (including laparoscopic technologies). But the time when the CMC is in the body is insufficient to prevent the formation of adhesions, particularly in the presence of non-absorbable rigid implants. The reactive functional groups in CMC allow to transform the CMC-macromolecule into a spatial structure. For this are required the using of bifunctional (bicarboxylic or aminocarboxylic) acids and the transform of a part of the carboxyl groups from the Na-form to the hardly soluble H-form, i.e., it is necessary to crosslink CMC-macromolecules. Adipic acid and glutaric acid, aminoacetic acid and amino capronic acid used are linking agents. The influence of modification parameters on the degree of polymers swelling in water is studied. As a result, to obtain membranes designed for the treatment of adhesive disease, it is recommended to use additives in CMC of bifunctional compounds.

Biomechanical characterization of custom-made dynamic implants fabricated by Electron Beam Melting for anterior chest wall reconstruction

Large thoracic defects need to be reconstructed to restore inner organs protection and normal ventilation. Early rigid implants have provided the stabilization of the ribcage; however, those have been associated with breathing restrictions. The evolution of additive manufacturing has enabled the production of 3D custom-made thoracic implants. This has led to case reports on reconstructions with these prostheses, particularly for large anterior resections. A novel design of thoracic implant with dynamic capacity has already been reported, with promising short-term outcomes. However, specific biomechanical studies are needed to clarify its mechanical behaviour. A study of the evolution of the design of dynamic thoracic implants was carried out and such implants were biomechanically tested. Furthermore, finite element analyses were carried out to obtain a simple and reliable model to predict the implant behaviour, considering a rib and its costal cartilage. In the models, the stiffness and stress distribution along the implant and the bone showed that the reconstructions exhibited adequate mechanical behaviour. One of the designs provided a flexibility that closely matched the native model and the maximum stress values did not exceed the 30% of the yield strength of Ti-6Al-4V. The implants strength was demonstrated to be sufficient under tested conditions.

HALLUX PROXIMAL PHALANX FRACTURE IN ADULTS: AN OVERLOOKED DIAGNOSIS.

ABSTRACTObjectives: To describe the surgical treatment of fractures that involves the hallux interphalangeal joint, current indications and management options. Methods: we performed a literature review of relevant clinical studies in multiple databases, including PubMed, MedLine and Scopus, from January 1989 to October 2020. Results: There is consensus for surgical treatment of intra-articular fractures with a deviation greater than 2 mm, metadiaphyseal fractures with malrotation and/or malangulation, open fractures and unstable fractures. Conclusion: The use of more rigid implants allow alignment maintenance during healing process and lower risk of reduction loss. Valgus deformity and interphalangeal joint osteoarthritis are possible complications that must be avoided. Level of Evidence III, Systematic review of Level III studies.

Utilizing 2.0 mm Plates as a Supplemental Fixation Aid: A Technique For Complex Fractures

Direct reduction and rigid fixation of periarticular fractures such as those about the distal humerus present unique challenges to the orthopedic surgeon. Obtaining reduction of fracture fragments with conventional methods such as reduction forceps and Kirschner wires may obscure visualization, impede further reduction, and compromise placement of rigid implants. The use of the 2.0 mm mini-fragment nonlocking plate, a commonly available implant produced by several manufacturers, is presented as a method to address these challenges. Early clinical results from our series demonstrate the clinical utility of this technique.

Allogeneic and Alloplastic Augmentation Grafts in Nipple-Areola Complex Reconstruction: A Systematic Review and Pooled Outcomes Analysis of Complications and Aesthetic Outcomes.

With advancements in materials engineering, many plastic surgeons have looked to allogeneic tissue and alloplastic materials as a possible source of structure for long-lasting nipple-areola complex reconstruction. Furthermore, in light of the recent mandate from the Food and Drug Administration restricting the marketing and direct indication of acellular dermal matrices (ADMs) in breast reconstruction, we sought to highlight the overall safety and efficacy demonstrated in the existing literature surrounding all alloplastic materials in nipple-areola complex reconstruction. In this study, the authors conduct a systematic review and pooled outcomes analysis on allogenic and alloplastic implant materials utilized to achieve long-lasting nipple projection stratified by specific material used and respective outcomes. A comprehensive systematic review on allogenic and synthetic materials data utilized in nipple reconstruction was conducted utilizing Medline/PubMed database. Articles were stratified by (1) alloplastic material, as well as (2) objective and patient-reported outcomes. A total of 592 nipple-areola complexes on 482 patients were featured in 15 case series. In all studies, alloplastic or allograft material was utilized to achieve and maintain nipple projection. Subjective measurements revealed a patient satisfaction rate of 93.3% or higher with the majority of patients being very satisfied with their reconstruction. The alloplastic and allograft implants analyzed had an overall complication rate of 5.3% across all materials used. The most common complication reported was flap or graft necrosis with a pooled rate of 2.5%. Overall, the Ceratite implant presented with the highest complication rate (18%) including flap/graft necrosis (13%) and extrusion of the artificial bone (5%). Other rigid implants such as the biodesign nipple reconstruction cylinder reported complications of extrusion (3.6%), projection loss requiring revision (2.5%), wound dehiscence/drainage (1.5%), flap or graft necrosis (1.0%) and excessive bleeding (0.5%). ADM implants had reported complications of both insufficient projection (0.8%) and excessive projection (1.6%), which required surgical revision. Injectable materials had minimal reported complications of pain during injection (0.8%) with Radiesse and a false-positive PET scan result (0.8%) with DermaLive. Allogeneic and alloplastic grafts are a reliable means of achieving satisfactory nipple projection, with a relatively low overall complication profile. The use of Ceratite (artificial bone) led to the highest complication rates. Further clinical studies are necessary to better understand the feasibility and longer-term outcomes of the use of allogeneic and synthetic augmentation grafts to improve nipple projection. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Real consequences of improved histocompatibility: A microscopic study of flexible organics vs standard rigid implants in mice and the effect on seizure onset

Real consequences of improved histocompatibility: A microscopic study of flexible organics vs standard rigid implants in mice and the effect on seizure onset

CMOS-Compatible, Flexible, Intracortical Neural Probes.

Our goal is the development of a novel neural probe that combines flexibility with the functionalities of active CMOS-based probes. We interface CMOS-based probe tips of only a few millimeters in length with flexible polyimide cables, which enable the complete implantation of the tips into brain tissue. The multilayer platinum metallization of the cables is patterned using a novel combination of ion beam and plasma etching. Implantation of the flexible probes is verified in brain models using stiff insertion shuttles. We assembled neural probes from passive and active tips as short as 1.5 mm and less than 180μm in width. Active probes feature electrode arrays with 72 recording sites and multiplexing to 16 parallel output lines. We reliably patterned cables with signal lines of 2μm in width and 3μm in spacing. Ion beam etching deteriorated the composition of the polyimide substrate and its resistance to around 1kΩ. An additional plasma treatment re-established high insulation resistances and recovered the chemical composition. Probes were successfully implanted to a depth of 7mm using insertion shuttles and withstood forces of 63mN. This study presents the methods required for the fabrication and application of a new generation of neural probes. The synergetic approach surpasses the limitation of each individual probe technology and should be considered in future developments.

Microfluidic‐Release Insertion Shuttle Designed for Implanting Flexible Biomedical Electronic Devices into Live Bodies

AbstractImplantable biomedical devices in flexible forms are attractive as they are more mechanically compatible with soft live tissues than rigid implants. The flexible implants can bend comfortably instead of delivering stress or strain to the surrounding live tissues when they are exposed to external stresses. However, because of the nature of the mechanical properties, the flexible biomedical implants have one important drawback, difficulty in handling the floppy implants without bending or wrinkling when inserting through small incision of live tissues. Here, the microfluidic‐release insertion shuttle is presented, which delivers flexible implants through the live tissues with added stiffness and releases the implants by dissolving a temporary adhesive layer with controlled infusing releasing solution through the structures such as post array and microfluidic channel. Experimental studies with variations in design parameters such as radii and pitches of the post array provide design guidance of the insertion shuttle. The results include in vivo experiments with functional flexible electronic implants into a live pig animal model to demonstrate feasibility of the concept.

Upper-eyelid weight implants for patients with lagophthalmos—comparison of rigid and flexible implants

IntroductionFor treatment of lagophthalmos, metallic weight implants can be inserted in the upper eyelid to aid eyelid closure. Rigid and flexible implants are available. The objective of this study was to investigate the effect of implant type and patient variables on the survival of lid load implants. Materials and methodsForty-four patients with lagophthalmos were recruited to undergo upper-eyelid weight implantation. The predictor variable was type of implant inserted (rigid or flexible). The outcome variable was survival of the inserted implant (survival or extrusion). Other study variables were demographic data (age, gender), implant features (material, weight), and other conditions, such as history of radiation. An NMLE test was used to compare implant survival, depending on implant type (flexible versus rigid). Other variables were analysed by use of a χ2 test. ResultsForty-four participants were recruited, 29 female (65.9%) and 15 male (34.1%). Forty-six implants (23 rigid implants, 50.0%; 23 flexible implants, 50.0%) were inserted (bilateral implantation in two patients). The average weight of implants used was 1.76 g (range 1.4–2.2 g). One to two years after surgery, average vertical aperture (eyelid gap) for the closed eye was 0.65 mm (range 0–4 mm). Incidence of extrusion was 15.2% (one in the rigid implant group, 2.2%; six in the flexible implant group, 13.0%). Incidence of extrusion was significantly higher for flexible implants than for rigid implants (p = 0.0273). ConclusionsThe study results suggest that flexible implants are more likely to perforate the skin. The assumed advantages of the expensive chain lid weight must, therefore, be re-evaluated.

Settable polymer/ceramic composite bone grafts stabilize weight-bearing tibial plateau slot defects and integrate with host bone in an ovine model

Bone fractures at weight-bearing sites are challenging to treat due to the difficulty in maintaining articular congruency. An ideal biomaterial for fracture repair near articulating joints sets rapidly after implantation, stabilizes the fracture with minimal rigid implants, stimulates new bone formation, and remodels at a rate that maintains osseous integrity. Consequently, the design of biomaterials that mechanically stabilize fractures while remodeling to form new bone is an unmet challenge in bone tissue engineering. In this study, we investigated remodeling of resorbable bone cements in a stringent model of mechanically loaded tibial plateau defects in sheep. Nanocrystalline hydroxyapatite-poly(ester urethane) (nHA-PEUR) hybrid polymers were augmented with either ceramic granules (85% β-tricalcium phosphate/15% hydroxyapatite, CG) or a blend of CG and bioactive glass (BG) particles to form a settable bone cement. The initial compressive strength and fatigue properties of the cements were comparable to those of non-resorbable poly(methyl methacrylate) bone cement. In animals that tolerated the initial few weeks of early weight-bearing, CG/nHA-PEUR cements mechanically stabilized the tibial plateau defects and remodeled to form new bone at 16 weeks. In contrast, cements incorporating BG particles resorbed with fibrous tissue filling the defect. Furthermore, CG/nHA-PEUR cements remodeled significantly faster at the full weight-bearing tibial plateau site compared to the mechanically protected femoral condyle site in the same animal. These findings are the first to report a settable bone cement that remodels to form new bone while providing mechanical stability in a stringent large animal model of weight-bearing bone defects near an articulating joint.