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Open reduction internal fixation (ORIF) metal plates provide exceptional support for unstable bone fractures; however, they often result in debilitating soft-tissue adhesions and their rigid shape cannot be easily customized by surgeons. In this work, a surgically feasible ORIF methodology, called AdhFix, is developed by combining screws with polymer/hydroxyapatite composites, which are applied and shaped in situ before being rapidly cured on demand via high-energy visible-light-induced thiol–ene coupling chemistry. The method is developed on porcine metacarpals with transverse and multifragmented fractures, resulting in strong and stable fixations with a bending rigidity of 0.28 (0.03) N m2 and a maximum load before break of 220 (15) N. Evaluations on human cadaver hands with proximal phalanx fractures show that AdhFix withstands the forces from finger flexing exercises, while short- and long-term in vivo rat femur fracture models show that AdhFix successfully supports bone healing without degradation, adverse effects, or soft-tissue adhesions. This procedure represents a radical new approach to fracture fixation, which grants surgeons unparalleled customizability and does not result in soft-tissue adhesions. QC 20210623

Bone damage patients may suffer from metal toxicity resulting from an adverse reaction. To avoid the need for a second operation, we set out to identify a material that can be used as a substitute for metal in small fragment plates, which is compatible with the human body. Thus, in this study, we set out to study the development of a material that can be applied to the small fragment plate, based on a hydroxyapatite (HA)-polylactic acid (PLA) composite. This study examined three main factors, namely, the ratio of the PLA to the HA, injection temperature (T) and injection pressure (P). Based on the ASTM standard, the best results (Code 4 and Code 1) obtained from the mechanical property tests (tension and flexural) were 44.02 MPa and 63.97 MPa, respectively. When compared to HA-HDPE, our material offers both strength and biodegradable/biocompatible advantages. By inspection with scanning electron microscope (SEM) and energy-dispersive spectrometry (EDS), we could identify the components of the HA and distribution pattern. In terms of biocompatibility, Code 1 is promising. To maximize the composite desirability, optimal condition was mathematically calculated. In addition, finite element analysis confirmed that the proposed bone fixation plate would not be damaged when the wrist is impacted.

BackgroundCerclage wire is the current standard for circumferential bone fixation. Advances in technology have improved modern sutures, allowing for expanded utility and broader application. The present study compared the strength and durability of cerclage fixation between modern suture materials and monofilament wire.MethodsThe Surgeon’s Knot, the Nice Knot and the Modified Nice Knot, were each tied using three separate suture materials: no. 2 FiberWire (Arthrex, Naples, FL, USA), no. 2 Ultrabraid (Smith & Nephew, Andover, MA, USA) and no. 5 Ethibond (Johnson & Johnson, Somerville, NJ, USA). These sutures were compared with monofilament wire. Sutures were secured around a fixed diameter using three additional half hitches, whereas a 1.2-mm (18 gauge) stainless steel monofilament wire was used for comparison. One fellow and one orthopaedic surgery resident each tied five trials with every knot/material combination. Samples were subjected to cyclic loading and quasi-static load testing. Respectively, cyclic displacement over time and load to failure were analyzed. Clinical failure (3 mm of cyclic displacement) and absolute failure (opening of the knot or material failure) were the outcomes of interest.ResultsDuring cyclic loading, Ethibond displaced significantly less over time compared to monofilament wire ( p ConclusionsHigh-performance sutures achieve superior results in biomechanical testing under cyclic and quasi-static load compared to monofilament wire, suggesting that they provide an alternative to wire for cerclage fixation with select clinical application. Biomechanical security of suture cerclage is dependent on suture material, although it is not altered significantly by choice of knot. An ex-vivo study with clinical application would further reinforce whether suture cerclage offers a valid alternative to wire cerclage.

In this study, we investigated the in vitro cytotoxicity and in vivo biosafety of reinforced polylactide (PLA) composites with hyaluronic acid-chitosan (HACS) complex and β-tricalcium phosphate (β-TCP) powder. The cytotoxicity of HACS/PLA (with β-TCP) composites was almost the same as that of neat PLA indicating that HACS/PLA (with β-TCP) composites did not have toxic effects. In in vivo biosafety tests using X-ray and micro-CT imaging, HACS/PLA (with β-TCP) composites did not show any fracture during 20 weeks of implantation in the tibia and femur of rabbits. The HACS/PLA (with β-TCP) composites did not induce severe inflammatory responses such as recruitment of macrophages around the implantation site, as assessed by H&E and immune staining of biopsy samples, for 6 weeks after insertion into SD rats. Addition of β-TCP powder to HACS/PLA composite enhanced bone induction and regeneration. The HACS/PLA composites prepared in the present study have potential maxillofacial and orthopedic applications.

Background Adequate fixation of replanted digits is essential not only for short-term healing but for long-term function. Various bony fixation methods using Kirschner (K-) and intraosseous wire are available in replantation. We examined clinical and radiographic outcomes of fixation methods on bone union after digital replantation. Methods A single institutional retrospective review identified 992 patients who had undergone 1,247 successful replantations between July 2009 and September 2015. Exclusion criteria included amputations of the distal phalanx, comminuted fractures, and intra-articular fractures. Patients were classified according to 5 categories of fixation methods: single K-wire, double longitudinal K-wires, cross K-wires, wire with, and wire without K-wire support. Bone union was evaluated by 5-month postoperative X-ray and fixation outcomes were compared across the 5 groups. Results The exclusion criteria were applied, and 88 patients with 103 replanted digits remained for analysis. Single K-wire fixation was used in 40 digits, double longitudinal K-wires in 30, and cross fixation in 14. Wire with and without K-wire support was required in 15 and 4 digits. Nonunion was observed in 32 digits (31.1%), of which 13 required additional operations such as bone graft or corrective osteotomy. The highest percent of nonunion was observed after cross fixation (35.7%) and the lowest after wire alone (25.0%). Conclusions In this study, contrary to general knowledge, we found that single K-wire fixation was not associated with poorer outcomes. Successful bone union outcomes may be achieved by careful selection of bone fixation methods. This study provides useful information for planning bone fixation in digital replantation.

Iliac crest bone grafting is very common associated procedure in various bone fixation surgery. We report here successful use of Transversalis fascia plane (TFP) block for iliac crest bone harvesting in a Polytrauma patient with difficult airway.

Polylactic acid (PLA)-based polymers are ubiquitous in the biomedical field thanks to their combination of attractive peculiarities: biocompatibility (degradation products do not elicit critical responses and are easily metabolized by the body), hydrolytic degradation in situ, tailorable properties, and well-established processing technologies. This led to the development of several applications, such as bone fixation screws, bioresorbable suture threads, and stent coating, just to name a few. Nanomedicine could not be unconcerned by PLA-based materials as well, where their use for the synthesis of nanocarriers for the targeted delivery of hydrophobic drugs emerged as a new promising application. The purpose of the here presented review is two-fold: on one side, it aims at providing a broad overview of PLA-based materials and their properties, which allow them gaining a leading role in the biomedical field; on the other side, it offers a specific focus on their recent use in nanomedicine, highlighting opportunities and perspectives.

This systematic review investigates factors associated with outcomes after meniscal allograft transplantation (MAT). The PubMed, Scopus, and Cochrane Central Register databases were used to search relevant articles in April 2018. Studies that evaluated at least one association between a factor and outcomes were extracted. Of 3,381 titles, 52 studies were finally analyzed. Data about predictors, patient-reported outcome scores (PROMs), and failure rates were extracted for quantitative and qualitative analysis. A total of 3,382 patients and 3,460 transplants were identified. Thirty different predictors were reported in the current MAT literature, 18 of which by at least two studies. Subgroup analysis showed that lateral MAT had higher postoperative values than medial MAT in Lysholm's (p = 0.0102) and International Knee Documentation Committee (IKDC; p = 0.0056) scores. Soft tissue fixation showed higher postoperative IKDC scores than bone fixation (p = 0.0008). Fresh frozen allografts had higher Lysholm's scores (p

Trabecular resorption from interdigitated regions between cement and bone has been found in postmortem-retrieved knee replacements, but the viability of interdigitated bone, and the mechanism responsible for this bone loss is not known. In this work, a Sprague-Dawley (age 12 weeks) rat knee replacement model with an interdigitated cement-bone interface was developed. Morphological and cellular changes in the interdigitated region of the knee replacement over time (0, 2, 6, or 12 weeks) were determined for ovariectomy (OVX) and Sham OVX treatment groups. Interdigitated bone volume fraction (BV/TV) increased with time for Sham OVX (0.022 BV/TV/wk) and OVX (0.015 BV/TV/wk) group, but the rate of increase was greater for the Sham OVX group (p = 0.0064). Tissue mineral density followed a similar increase with time in the interdigitated regions. Trabecular resorption, when it did occur, started at the cement border with medullary-adjacent bone in the presence of osteoclasts. There was substantial loss of viable bone (~80% empty osteocyte lacunae) in the interdigitated regions. Pre-surgical fluorochrome labels remained in the interdigitated regions, and did not diminish with time, indicating that the bone was not remodeling. There was also some evidence of continued surface mineralization in the interdigitated region after cementing of the knee, but this diminished over time. Statement of clinical significance: Interdigitated bone with cement provides mechanical stability for success of knee replacements. Improved understanding of the fate of the interdigitated bone over time could lead to a better understanding of the loosening process and interventions to prevent loss of fixation. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2163-2171, 2019.

Hinged implants are the most constrained knee replacement prostheses. They are very useful in complex cases of total knee arthroplasty (TKA) revision. Hinged implants have evolved with rotating bearings and modularity that allows local joint reconstruction or segmental bone replacement. They are required when significant instability persists in cases with inadequate collateral ligaments and significant flexion laxity. They are now used when a large bone defect is reconstructed, or when bone fixation of the implant is questionable especially in the metaphyseal zone. The use of hinged implants in TKA revision is associated with high complication rates. Published outcomes differ based on the patients’ aetiology. The outcomes of rotating-hinged implants used in septic revisions or salvage situations are poorer than other types of revision and have a higher complication rate. The poor general health of these patients is often a limitation. Despite these relatively poor results, hinged implants continue to have a place in revision surgery to solve major instability or to obtain stable bone fixation of an implant when the metaphysis is filled with bone grafts or porous devices. Cite this article: EFORT Open Rev 2019;4 DOI: 10.1302/2058-5241.4.180070

Bone resorption around stress-shielded area in bone fixation treatments is an important consideration within clinical sectors.

Currently, the most of implant products that sold in Indonesia are imported products. The Ministry of Health and the Ministry of Research, Technology and Higher Education stimulate domestic implant production as an alternative for imported products that have been dominating domestic market. This study aims to observe domestic titanium screw performance especially from torque and pullout performance based on ASTM F-532 about test method for a metallic bone screw. The implant specification that observed is screw M1.5 for maxillofacial region. Those performances are tested using experimental approach, Finite Element Analysis (FEA), and mathematical approach for pullout and only experimental approach for torque test. The results of this study show that the value of pullout from the developed domestic titanium screw UI and commercial screw are 10.02 N and 11.88 N, respectively. This result for domestic screw UI is not slightly different from the result which using FEA approach with error 10.30 % for pullout. In the other hands, analytical approach using Chapman modified method gives 1% error for pullout. The result of this study shows that the value of pullout performance of domestic titanium screw is equal with imported commercial product. For torque performance, domestic screw UI has value 0.029 Nm which is as good as commercial screw with value 0.028 Nm. But, domestic screw needs more force to drive the screw into the test block because it has duller tip than commercial screw.

The development of biodegradable devices for fracture fixation and guided bone regeneration has been intense for three decades. An optimal device should not cause any local or systemic disorders and should degrade slowly, transferring the stress to the healing bone. Hence, it need not be removed after the fracture or defect has healed.

Finger replantation in ring avulsion injuries may be particularly challenging. A stable bone fixation is required previously to neurovascular reparation. Several bone fixation methods have been described in digital replantation, such as single or double K-wire fixation, or intraosseus wire. This case report illustrates the utilization of a partially threaded cannulated axial screw, which provides reliable bony stability, and allows a one-stage surgical procedure in digital replantation. Those factors allow for early motion of the digit and allow prompt recovery of finger functionality.

Conventional methods of bone repair and regeneration such as autografts, allografts, and xenografts suffer from various disadvantages that has led to the evolution of resorbable polymers in bone repair and regeneration. The resorbable polymers are resorbed by the body, thus avoiding the additional surgery for implant removal. In this chapter, the advantages of resorbable polymers over conventional materials such as metals and ceramics are described. Resorbable polymers used in combination with metals, ceramics, and other polymers significantly enhance the mechanical, chemical, physical, and structural properties of the implant, and therefore resorbable composites serve as better implants. The potential of resorbable polymers and composites in bone fixation and bone tissue engineering is described, indicating the applicability of these materials in bone repair and regeneration.

[EN] Finite element method has been employed to establish the feasibility of a fixation plate made of PLA by additive manufacturing for femoral shaft fractures. For this purpose, Von Mises stress and the pressure contact between bones had been analysed. The proposed design has been compared with an actual titanium fixation plate as a point of reference., J. Ivorra-Martinez is funded with a Formación de Profesorado Universitario (FPU) grant from the Spanish Government (Ministerio de Ciencia, Innovación y Universidades), with reference FPU19/01759.

In reconstructive hand surgery, flaps and therefore microsurgical techniques are inevitable to provide the best functional and aesthetic results. There are various complications of defect repair with microsurgical methods. We aimed to classify subacute and late unexpected complications that develop after defect repair by microsurgical methods and to present the management. Patients who underwent microvascular flap surgery for upper extremity tissue defects between 2014-2018 were included in the study. Complications other than total flap loss were retrospectively investigated and recorded. 8 patients (6 Male, 2 Female) were included to the study. 5 left and 3 right hand defects were detected. 3 fingers, 3 hand dorsum, 1 wrist and 1 forearm defects were detected. 2 marginal necrosis, 2 partial flap loss, 1 venous insufficiency, 1 nonunion, 1 skin contracture and 1 burn were the determined complications. Most defects present with different traumas in hand. The trauma zone is almost always close to the area of microvascular repair, moreover the recipient artery may not always be intact. How the bone fixation is performed is very important, covering the bone should be provided with well-blooded tissues. While providing all these, this coverage should not be bulk and should not restrict the range of motion in the hand. Having grasping function necessitates a repair that puts the function in the foreground compared to other areas in the body. Subclinical infections of hand in patients presenting with post-traumatic defects may cause nutritional problems, which may impair wound healing. Such a problem can also be confused with the arterial deprivation of the flap. The absolute sense requirement distinguishes the hand area from the reconstruction of many areas. All these are challenging difficulties in choosing flap for defects in the hand. [Hand Microsurg 2021; 10(2.000): 116-126]

Background Allografts and recycled bone autograft are commonly used for biological reconstruction. The dual locking plates fixation method has been advocated for increasing allograft stability and preventing fixation failure; however, the biomechanical properties of the various configurations of dual locking plates have not been extensively studied. Methods In a finite element (FE) analysis, we developed 6 patterns of different dual locking plate configurations for fixation of the mid shaft of the femur. The maximum strains were recorded for each of the 6 models then axial, bending and torsion stiffness were calculated. The FE analysis was validated the results with mechanical testing (axial compression, bending, and torsional stiffness) on a cadaveric femur. Findings The highest axial compression (715.41 N/mm) and lateral bending (2981.24 N/mm) was found in Model 4 (with two 10-hole locking plates placed at the medial and lateral side), while the highest torsional stiffness (193.59 N·mm /mm) was found in Model 3 (with 8- and 10-hole locking plates placed at the posterior and lateral side). Excellent agreement was found between the finite element analysis and biomechanical testing (r2 = 0.98). Interpretation The dual locking plate configuration with medial and lateral, 10-hole locking plates provided the most rigid and strongest fixation of the femur; both in terms of axial compression and lateral bending stiffness.

Using a ceramic-ceramic bearings, cementless total hip arthroplasty (THA) has provided good clinical results. To ensure longevity a good quality fixation of the implants is mandatory. Different surface treatments had been used, with inconsistent results. We hypothesized that a “bilayer coating” applied to both THA components using validated technology will provide a long-lasting and reliable bone fixation. We studied the survival and bone integration of a continuous, single-surgeon, retrospective series of 126 THA cases (116 patients) with an average follow-up of 12.2 years (minimum 10 years). The THA consisted of cementless implants with a bilayer coating of titanium and hydroxyapatite and used a ceramic–ceramic bearing. With surgical revision for any cause (except infection) as the end point, THA survival was 95.1 % at 13 years. Stem (98.8 %) and cup (98.6 %) survival was similar at 13 years. Bone integration was confirmed in 100 % of implants (Engh-Massin score of 17.42 and ARA score of 5.94). There were no instances of loosening. Revisions were performed because of instability (1.6 %), prosthetic impingement or material-related issues. A bilayer titanium and hydroxyapatite coating provides strong, fast, reliable osseo integration, without deterioration at the interface or release of damaging particles. The good clinical outcomes expected of ceramic bearings were achieved, as were equally reliable stem and cup fixation.

Das Operationsziel ist eine stabile Refixierung des triangularen fibrokartilaginaren Komplexes (TFCC) in der Fovea ulnaris. Hierdurch soll eine Stabilitat des distalen radioulnaren Gelenks (DRUG) nach gewisser Einheilungsphase wiederhergestellt und eine Reduktion der Schmerzen erreicht werden. Verletzungen der proximalen Komponente, also der fovealen Ansatze des TFCC, die zu einer Instabilitat des DRUG fuhren konnen oder bereits gefuhrt haben. Ebenso komplette Abrisse des TFCC von der Ulna, sei es ohne Fraktur des Processus styloideus ulnae oder mit Fraktur („floating styloid“). Zu umfangreiche akute oder chronische Schadigungen des TFCC ohne Aussicht auf eine adaquate Heilung sowie eine klinisch relevante Arthrose des DRUG. Vorsicht auch bei stark osteoporotischem Knochen. Nach diagnostischer Arthroskopie und Durchfuhrung der Stabilitatskontrolle des TFCC mit dem Tasthaken wird in Supinationsstellung des Handgelenks die Reposition des DRUG durchgefuhrt. Es erfolgt die Ankerfixierung uber den direkten fovealen (DF-)Zugang. Einbringen der Nahte durch den DF-Zugang unter arthroskopischer Kontrolle vom 3/4-Zugang aus und Herausziehen sowie Verknoten der Faden uber das 6U-Portal. Einschranken der Umwendbewegung des DRUG durch eine Munster-Gips- oder spezielle Oberarmschiene uber 6 Wochen, danach eigenstandige Bewegungsubungen. Nach 8 Wochen Kraftaufbau und Physiotherapie empfohlen. Klinische Studien an Patienten mit TFCC-Lasion und klinischer Instabilitat des DRUG zeigten signifikante Verbesserungen des Schmerzempfindens, der Beweglichkeit und des DASH-Scores nach Ankerrefixation. Alle Patienten arbeiteten nach der Operation wieder. Demnach kann durch diese Technik eine Stabilisierung des DRUG bei nur geringer Komplikationsrate erreicht werden.

Introduction Distal finger replantations are technically difficult operations due to small vessel sizes and narrow field of vision. The results of 25 distal finger replantations performed by dorsal approach are presented. The technical benefits and details of this technique is discussed with a literature review. Patients and methods Twenty-five distal finger replantations were performed by dorsal approach. In dorsal approach volar skin was repaired first and arterial and venous repairs were performed from dorsal side before bone fixation and nailbed repair. Twenty-one cases were Tamai zone I amputations 4 cases were Tamai zone II amputations. 3 amputations were in children and the other patients were adults. Nine amputations were transverse type and the others were oblique amputations. Results Twenty-three fingers survived and 2 fingers were lost despite revision surgeries (92% success rate). Dorsal approach provided about 2 times wider exposures compared to the volar approach. Fourteen patients had external bleeding to prevent congestion. Mean duration of external bleeding was 6.8 days (range, 6 - 8 days). Mean hospitalization period was 7.7 days (range, 6 - 10 days). The mean follow up period was 13 months (range, 6 - 28 months). Six patients had nail deformity. Four patients had pulp atrophy. Three patients had restriction of range of motion in distal interphalangeal joint. Conclusion Dorsal approach provides a better exposure of vessel repair sites without tension and helps in technical difficulties of distal finger replantation. All types of distal finger amputations are amenable to dorsal approach for vascular repairs and oblique amputations are ideal ones. © 2016 Wiley Periodicals, Inc. Microsurgery, 2016. © 2015 Wiley Periodicals, Inc. Microsurgery 36:628-636, 2016.

Open fractures have been considered one of the true orthopaedic emergencies by some, however, optimal treatment has not been definitively described. Significant debate has focused on the most appropriate method by which to manage open fractures, but general principles of treatment are well established. Principles include fracture classification, antibiosis, irrigation, debridement, wound management and fracture stabilisation. In this second in a two-part series on open fracture management, debridement, wound management and fracture stabilisation will be explored; the initial management of the patient was discussed in the first article in the series. Debridement should be performed on an urgent but not emergent basis; adequacy of debridement and timeliness of soft tissue coverage are probably more important than time from injury to debridement. Once the wound has been appropriately irrigated and thoroughly debrided, early aggressive treatment, with rigid bone fixation and soft tissue reconstruction, is widely accepted as the treatment of choice. Generally, type 1 and 2 open fractures can be stabilised using the same method of fixation as would be used for a closed fracture of similar configuration, while the extensive soft tissue damage associated with type 3 fractures may preclude internal fixation.

Partial wrist fusion is a useful technique for the treatment of such specific carpal disorders as arthritis, Kienböck’s disease, midcarpal instability, scaphoid nonunion, etc. Many techniques have been described by removing arthritic joint surfaces and transfering load, using, for bone fixation, K-wires, screws, staples, and more recently dedicated plates. The goal of this procedure is to maximise wrist motion and strength while minimizing or eliminating pain. The purpose of this article is to discuss the most commonly used combination of intercarpal arthrodeses, to clarify the indications for each fusion, to describe the appropriate surgical technique for each fusion, and to provide an overview of results and current concepts.Cite this article: Houvet, P. Intercarpal fusions: indications, treatment options and techniques. EFORT Open Rev 2016;1:45-51. DOI: 10.1302/2058-5241.1.000019.

Category: Basic Sciences/Biologics; Other Introduction/Purpose: The integration of an implant into surrounding tissue as remodeling occurs is a characteristic associated with bone grafts or bone fillers, some of which are osteoconductive or osteostimulative. Many bioabsorbable polymer implants lack quiescent degradation and are associated with adverse inflammation. Recently, new bio-integrative bone fixation implants comprised of continuous mineral fibers and polymer were introduced. The implant’s high mineral content is intended to encourage an increased bio-integrative response, while the continuous fiber structure provides mechanical bone fixation strength. The study objectives were to evaluate the implant’s long-term bio-integration and ability to maintain fixation in a load bearing in- vivo model. Methods: Twenty-four rabbits were studied over 104-week period to evaluate the bio-integration of fiber-reinforced bone fixation pins. The continuous reinforcing mineral fibers made up approximately 50% of the implant, comprised of elements found in native bone, including calcium, silica, and magnesium. The other 50% was comprised of poly (L-lactide-co-D, L lactide) (PLDLA) at a 70:30, L:DL ratio. Pins were implanted bilaterally, with three fiber-reinforced pins (test) implanted into the mid-shaft of one femur and three PLDLA polymer pins (control) into the mid-shaft of the other femur. Implantation sites were scored histologically at multiple timepoints to assess bio-integration by means of implant degradation profile, surrounding bone quality and tissue ingrowth. A separate group of twelve rabbits was studied clinically, radiographically and histologically over 12 weeks to evaluate the fiber-reinforced implant performance, compared to a stainless-steel implanted group, in a lateral femur condyle osteotomy model under full load bearing conditions. Results: At 104 weeks, implant material fully eliminated in 11 out of 12 fiber-reinforced implants and in 6 out of 12 PLDLA implants. The fiber-reinforced group showed increased propensity for bio-integration throughout the course of the study, demonstrating a gradual degradation profile and much higher score of tissue ingrowth. Amount of polymer decreased from a score of 4.0 at 4 weeks to score 1.7 at week 26, score 1.0 at week 78 and 0.1 at 104 weeks. The polymer control underwent abrupt late stage degradation, with amount of polymer dropping from a score of 4.0 to 0.7 from 78 to 104 weeks. In the load bearing osteotomy model, the fiber-reinforced implants performed comparable to stainless-steel, demonstrating tighter bone-to- implant interface with no intervening fibrotic tissue. Conclusion: This study represents the first long term in-vivo evaluation of mineral fiber-reinforced implants demonstrating both bio-integration and orthopedic fixation. Quiescent bio-integration is a significant challenge for degradable orthopedic fixation implants. The implants must be mechanically strong for stable fixation while able to gradually integrate with surrounding bone without adverse effects. Continuous fiber reinforced implants proved the unique potential to meet this challenge with a fiber structure that provides fixation strength and is comprised entirely of minerals found in native bone. An increased level of mesenchymal tissue ingrowth, combined with the absence of local or systemic adverse response, demonstrates excellent bio- integration.

Several surgical procedures have been described to correct the deformities associated with craniosynostosis. To simplify the prediction of results, virtual planning techniques and image-guided surgery have been used. Digital planning can be transferred to the operating room using osteotomy and cutting guides or surgical navigation. We describe a novel bone fixation method that allows for anchoring of a cranial dynamic reference frame (DRF) in a steady manner. DRF can be used for registration and as a reference for surgical navigation in an infant's skull. We describe this novel technique to overcome the problems of DRF fixation on an infant's thin and weak calvarium. We fixed the DRF to the cranium using this new system. A 6-hole X-shaped miniplate was placed using 5 screws, leaving 1 of the central holes free. The self-drilling screw that anchors the DRF in position was placed in the free central hole, avoiding calvarial bone breakage and allowing for surgical navigation. To the best of our knowledge, the present study is the first report of this DRF anchorage modification for surgical navigation during surgery of craniosynostosis in an infant.

Case This was a postmortem retrieval study to assess bone fixation in a hydroxyapatite-coated ACTIS stem and a beaded Pinnacle Sector cup retrieved from an 89-year-old man 15-months postoperatively. Previous radiographic examinations showed good implant fixation without any radiolucency. The sectioned cup and stem showed good fixation on visual, microradiographic, and histological examinations. Slight changes in bone density and mineral content were observed. Conclusions Clinical fixation was achieved in both components with variable degrees of bone ingrowth and ongrowth at 15 months postoperatively in this postmortem retrieval case.

Background: Due to bone cutting loss from self-tapping screws (STS), progressive destruction of bone can occur with each reinsertion during surgery. When considering the use of jigs that utilize multiple insertions such as those seen in ulnar and radial shortening osteotomy systems, or scenarios where a screw needs to be removed and reinserted due to some technical issue, this can be concerning, as multiple studies examining the effects of multiple reinsertions and the relationship between insertional torque and pullout strength have had mixed results. Methods: Insertional torque and pullout strength were experimentally measured following multiple reinsertions of STS for up to 5 total insertions for various densities and locations along radial sawbone shafts. Results: Torque and pullout strength were significantly greater in middle segments of the radial shaft. Our trials corroborate previous literature regarding a significant reduction in fixation between 1 and 2 insertions; beyond this, there was no significant difference between pullout strength across all segment locations as well as bone densities for 3 to 5 insertions. There was a moderate to high correlation of insertional torque to pullout strength noted across all bone densities and segments (Pearson r = 0.663, P < .001). Conclusion: While reinsertion of STS between 1 and 2 insertions has been shown to significantly differ in pullout strength, beyond this, there does not appear to be a significant difference in up to 5 insertions at any specific region of radial bone across a range of sawbone densities. Further insertions may be considered with caution.

Introduction: There are many screw and thread designs commercially available to surgeons for bone fixation. There is a paucity of literature on comparative mechanical properties of various screw and thread designs including variable pitch screws, and tapered screws. This purpose of this study was to test whether varying a screws thread pitch and/or tapering a screws core diameter alters the mechanical performance of screws. Methods: A mechanical pullout test was performed on 4 different screw designs, including a variable pitch screw, a constant pitch screw, and variations of these in a straight and tapered screw design. Three-dimensional printing technology was used to manufacture the metal screws in order to control for as many variables as possible. Results: The pullout strength of the constant pitch screws (304.9 ± 25.3 N, P < .001) was significantly greater than the variable pitch screws (259.7 ± 23.4 N). The pullout strength was also significantly greater for screws with a tapered diameter (305.4 ± 24.1 N) than a constant diameter (259.1 ± 23.5N, P < .001). Tapered diameter variable pitch screws had the largest stiffness overall, which was statistically significant against all other groups ( P ⩽ .001). Conclusion: The pullout strength is significantly greater for screws with a tapered diameter than a constant diameter and greater for screws with a constant pitch than for a variable pitch. Results of stiffness testing is mixed depending on the screw taper. The clinical significance of this study is that it provides data on the effects that thread design and tapering have on the pullout strength of screws. Levels of Evidence: Level V: Mechanical study

A new miniplate applied differently from conventional application method for bone fixation has been developed. The novel approach is the insertion of the screw into the bone before miniplate installation. This study aimed to assess the stress distribution of a newly designed Yang’s Keyhole (YK)- plate for segmental-bone fixation during sagittal split ramus osteotomy (SSO). Moreover, the effectiveness of the YK-plate system based on the clinical results was determined. The YK-plate system has a widened hole in the anterior region to permit a screw-head to be screwed through the system. The stress distribution using the finite-element analysis method was compared between in the case of the YK-plate system and the case of existing mini-plate fixation technique. Moreover, the clinical results of patients were evaluated during the follow-up examination periods. No critical complications in any of the six patients were reported during the four-month follow-up period. The result of the stress distribution using finite-element analysis showed a similar trend in all four fixation methods. The YK-plate system can be applied to fixation during SSO and allow for mechanically stable and convenient application.

Headless compression screws (HCSs) are commonly used to fixate small bones and articular fractures. Understanding the biomechanical efficacy of different HCS designs can help surgeons make proper interfragmentary compression when a specific implant is chosen. HCSs with three different central shaft designs (unthreaded, fully threaded, and partially threaded) were studied: the Herbert-Whipple, Mini-Acutrak 2, and headless reduction (HLR). Polyurethane foam blocks were machined with a simulated fracture gap of 0.5 mm and set onto a custom-made jig to simultaneously measure compression force and driving torque during screw insertion. The maximal achievable compression forces and driving torques recorded were 47.4 ± 0.9 N and 145.11 ± 1.65 N mm for the HLR, 50.98 ± 1.29 N and 152.62 ± 2.83 N mm for the Mini-Acutrak 2, and 19.33 ± 1.0 N and 33.4 ± 2.2 N mm for the Herbert-Whipple. Overall, the compression force of the Mini-Acutrak 2 and HLR increased with the torque. Unlike the other screws, the Herbert-Whipple's driving torque increased while the compression force decreased after peak compression force was achieved. The partially threaded shaft design (HLR) demonstrated equivalent biomechanical advantage with the Mini-Acutrak 2 in interfragmentary compression. The HCSs with cone-shaped proximal ends (HLR and Mini-Acutrak 2) maintained their compression force during over-fastening, whereas the unthreaded central shaft of the Herbert-Whipple screw caused it to lose compression force.

Purpose To evaluate if redirecting a Kirschner wire (K-wire) through the same proximal hole will weaken the pull-out force and to test if multiple redirections will result in a continued stepwise decrease in pull-out force. Methods An Instron was used to test the pull-out force of K-wires using the peak initial failure load as a measure of failure of K-wire fixation. K-wires 0.062 inches in diameter were inserted with an angled drill guide into a bicortical bone substrate. Trials were divided into 7 groups with the first group having the K-wires placed through both cortices and then tested without redirection. In groups 2–6, the K-wire was placed bicortically and then withdrawn and redirected through the same proximal hole with 1, 2, 3, 4, and 5 redirections. A control group in which the K-wire was only unicortical was also tested. Results Compared with the control group of no redirects, any number of redirections weakened the pull-out force. There was no difference between redirected groups and the unicortical group. When comparing between redirections, there were no significant differences in pull-out force. Regression analysis showed that, after the first redirection, there was no stepwise change in pull-out force with additional redirection. Conclusions There was a significant decrease in pull-out force with any redirections, but there was no stepwise decrease in failure force after multiple redirections. The failure force of any redirection was similar to a unicortically placed wire. Clinical relevance Any K-wire redirection attempts in hand bone fixation can result in a considerably weakened construct.

In vitro experimental tests are of great importance in human joint biomechanics. These tests allow the study of the kinetostatic and dynamic behaviour of human joints: a limb specimen is connected to a rig, controlled loads are applied, and the joint displacements are measured. Fixation of the bone to the rig is a typical problem that raises in these applications. A new fixation device is presented in this paper that features several interesting and innovative characteristics: it consists of a passive parallel mechanism that allows adjustment of the pose of the bone with respect to the rig with six degrees of freedom; if needed, the bone can be removed from the rig and repositioned exactly at the same pose during the experimental tests; all six degrees of freedom of the fixation device can be locked by acting only on two screws, thus simplifying the fixation operation; the parallel structure of the mechanism guarantees a high fixation stiffness. The complete design is presented and discussed, together with the results from the workspace and stiffness analyses of the mechanism, that are particularly important for the considered applications.