Organic polymer coating induced multiple heteroatom-doped carbon framework confined Co1-xS@NPSC core-shell hexapod for advanced sodium/potassium ion batteries

Synthesis of advanced structure and multiple heteroatom-doped carbon based heterostructure materials are the key to the preparation of high-performance energy storage electrode materials. Herein, the hexapod-shaped Co1-xS@NPSC has been triumphantly prepared using hexapod ZIF-67 as the sacrificial template to prepare Co1-xS inner core and N, P, and S tri-doped carbon (NPSC) as the shell through the carbonization of the organic polymer precursor. When applied as anode for Na+ batteries (SIBs) and K+ batteries (PIBs), Co1-xS@NPSC presents the high reversible specific capability of 747.4 mAh/g at 1.0 A/g after 235 cycles and 387.8 mAh/g at 5.0 A/g after 760 cycles for SIBs, as well as 326.7 mAh/g at 1.0 A/g after 180 cycles for PIBs. The excellent storage capacity and rate capability of Co1-xS@NPSC is ascribed to hexapod structure of ZIF-67 unlike the common dodecahedron, which is constructed with interior porous and exterior framework repository, donating supplemental active sites, and doping of multiple heteroatoms forming organic polymer coating inhibiting the volume expansion and restrains the agglomeration of Co1-xS nanoparticles. This approach has paved a bright avenue to exploit promising anode materials with novel structure and hetero-atom doping for high-performance energy storage devices.

Step-by-Step Nanoscale Top-Down Blocking and Etching Lead to Nanohexapods with Cartesian Geometry

In this research, we designed a stepwise synthetic method for Au@Pt hexapods where six elongated Au pods are arranged in a pairwise perpendicular fashion, sharing a common point (the central origin in a Cartesian-coordinate-like hexapod shape), featured with tip-selectively decorated Pt square nanoplates. Au@Pt hexapods were successfully synthesized by applying three distinctive chemical reactions in a stepwise manner. The Pt adatoms formed discontinuous thin nanoplates that selectively covered six concave facets of a Au truncated octahedron and served as etching masks in the succeeding etching process, which prevented underlying Au atoms from being oxidized. The subsequent isotropic etching proceeded radially, starting from the bare Au surface, carving the central nanocrystal in a concave manner. By controlling the etching conditions, Au@Pt hexapods were successfully fabricated, wherein the core Au domain is connected to six protruding arms, which hold Pt nanoplates at the ends. Due to their morphology, Au@Pt hexapods feature distinctive optical properties in the near-infrared region, as a proof of concept, allowing for surface-enhanced Raman spectroscopy (SERS)-based monitoring of in situ CO electrooxidation. We further extended our synthetic library by tailoring the size of the Pt nanoplates and neck widths of Au branches, demonstrating the validity of selective blocking and etching-based colloidal synthesis.

Circular external fixation for revision of failed tibia internal fixation

BACKGROUND

The management of failed tibial fracture fixation remains a challenge for orthopaedic surgeons. This study investigate the utility and outcomes of circular external fixation in the management of failed internal fixation of tibial fractures.

METHODS

Retrospective review of a prospectively collected database of a complex limb reconstruction unit at a major trauma centre was done during December 2022. Patients with failed internal fixation of tibial fracture who underwent revision surgery with circular external fixation frame were included.

RESULTS

20 patients with a mean age of 47.8 ± 16.5 years (range: 15-69) were included. Fourteen (70.0%) patients had failed plate and screws fixations, and the remaining six (30.0%) failed intramedullary nail fixation. The most common indication for revision surgery was development of early postoperative surgical site infection (5 patients; 25.0%). The mean duration of frame treatment was 199.5 ± 80.1 days (range = 49-364), while the mean follow-up duration following frame removal was 3.2 ± 1.8 years (range = 2-8). The overall union rate in this series was 100%; and all infected cases had complete resolution from infection. The total number of complications was 11, however, only two complications required surgical intervention. The most common complications reported were pin site infection (6; 30.0%) and limb length discrepancy of 2 cm (2; 10.0%).

CONCLUSIONS

Circular external fixation is a reliable surgical option in the treatment of failed internal fixation of tibia fractures. This technique can provide limb salvage in complex infected and noninfected cases with a high union rate and minimal major complications.

Comparison of complications and reoperations in AO/OTA 43.C3 pilon fractures treated with conventional ORIF versus minimally invasive hexapod ring fixation

INTRODUCTION

Controversy exists regarding the optimal management of AO/OTA 43. C3 pilon fractures. Open reduction and internal fixation (ORIF) is the gold standard treatment, but serious soft tissue and infectious complications have been previously reported. Minimally invasive strategies using hexapod ring fixation (HRF) with supplemental limited internal fixation have been used to reduce the incidence of complications. Previous studies have included heterogeneous types of pilon fractures, with non-comminuted injuries being more likely to be treated with ORIF and complex fractures receiving HRF treatment. To our knowledge, no studies have compared the complications and reoperation rates between ORIF and HRF exclusively for C3 fractures.

METHODS

Retrospective study comparing 53 patients treated for AO/OTA 43.C3 pilon fracture with ORIF or HRF in a trauma level I center with at least a two-year follow-up. Patients treated between January 2015 and January 2019 received ORIF and those treated between January 2019 and January 2021 received HRF. Complications were divided into two groups: minor (superficial infection and malalignment) and major (non-union, deep infection, and amputation). Reoperations, prevalence of ankle osteoarthritis, and requirement for ankle arthrodesis/total ankle replacement were registered.

RESULTS

We included 30 and 23 patients in the ORIF and HRF groups, respectively. The overall complication rate was similar in both groups, with 50% and 56,5% of the patients having complications in the ORIF and HRF groups, respectively (p:0,63). Minor complications were significantly more prevalent in the HRF group (p<0,001) whilst the ORIF group had a significantly higher rate of major complications (p<0,01). Superficial infections were highly prevalent in the HRF group (47,8%), as they were related to half-pin or K-wire infections. Deep infection was present only in the ORIF group, with 20% of the patients developing this major complication (p:0,03). Non-union rate, reoperations, ankle osteoarthritis, and the need for arthrodesis or ankle replacement showed no significant differences.

CONCLUSION

In AO/OTA 43.C3 fractures, HRF is safe and effective, achieving high union rates with a significantly lower rate of major complications compared to ORIF. According to our results, ORIF should be used cautiously for these types of fractures, considering the increased risk of deep infection.

A comparative evaluation of the time to frame removal for tibia fractures treated with hexapod and Ilizarov circular frames

INTRODUCTION

Traditional Ilizarov and hexapod frames have different biomechanical properties and there is limited literature regarding their effect on time to fracture union or time to frame removal.

METHODS

Tibial fractures managed with a circular frame at a tertiary limb reconstruction referral centre between 2011 and 2018 were retrospectively identified from a prospectively maintained database. They were classified into three treatment groups; Ilizarov style, Taylor Spatial Frame (TSF) and TrueLok Hex (TL-Hex). Data were extracted from electronic patient records and digital radiographs. The primary outcome was time to frame removal, which was seen as an indicator of clinical and radiological fracture union. Odds ratios were calculated with the clinical significance set at 30 days.

RESULTS

274 patients (median age 49 years, 36% female) were included in the analysis. 8.4% Ilizarov, 10.5% TSF and 13.5% TL-Hex frames required further surgery to aid fracture healing (p = 0.38). 30% of patients had open fractures. Median time to removal for Ilizarov, TSF & TL Hex frames was 167, 198 and 185 days respectively. There was a significant difference between Ilizarov and hexapod frames. Both TSF (OR 2.2, p<0.003) and TL-Hex (OR 1.8, p<0.04) had a significantly increased time to removal of 30 days or more compared with Ilizarov frames.The time to frame removal in metaphyseal fractures was significantly shorter for Ilizarov frame fixation than hexapod frames (p = 0.04). Open fractures were significantly more likely to require at least 30 days extra time to removal than closed fractures (OR 3.3, p<0.001). There was no significant difference in the time to frame removal between fracture location, age or sex.

CONCLUSION

Ilizarov frames have demonstrated a reduced time to frame removal in the management of tibial fractures than hexapod frames. Differences in the time to frame removal, an indicator of time to fracture union, may be due to the different mechanical properties of the frame, or early disruption of the fracture haematoma through secondary frame manipulation and fracture reduction, increased proportion of metaphyseal fractures treated with Ilizarov, or patient selection. The healing time was comparable across the tibia. Pooled meta-analyses may be able to further quantify these associations.

Outcomes of two circular external fixation systems in the definitive treatment of acute tibial fracture related infections

INTRODUCTION

Acute tibial fracture-related infection (FRI) is one of the most feared and challenging complications after a tibial fracture. The most appropriate treatment in this scenario is far from a resolved topic. Circular external fixators (CEFs) offer multiplanar control and minimize soft tissue injury using temporary implants far from the infected area. This study aimed to investigate the outcomes of two different types of CEFs (Ilizarov and hexapod) in the treatment of a series of acute tibial FRIs.

MATERIAL AND METHODS

A retrospective study at two specialized limb reconstruction centres identified all patients with an acute tibial FRI (≤4 weeks after index procedure) definitively treated with a CEF from January 2015 to December 2020.

PRIMARY OUTCOMES

fracture healing and infection eradication rate with a minimum FU of 12 months after frame removal.

SECONDARY OUTCOMES

to investigate the differences between the two types of circular frames regarding final post-treatment deformity magnitude.

RESULTS

We included 31 patients with acute tibial FRIs: 18 treated with hexapod-type and 13 with Ilizarov-type CEFs. Average age was 45.5±16.56 years. Fracture healing and infection eradication were achieved in all patients (31/31) after a mean follow-up of 24.7 months (range 12.1-55.3). Patients treated with an Ilizarov-type fixator presented shorter time to fracture union (5.5±2.2 months vs. 9.2±6.0 months; p-value 0.021) and shorter duration of external fixation (p-value 0.001). Regarding residual post-treatment deformity, the hexapod system presented significantly less residual coronal translation deformity (p-value 0.034) and better callus quality. Fixator-related complications were similar when comparing the two groups. No significant differences were seen in pain (p-value 0.25), RTW rate (35% vs. 45%; p-value 0.7) or functionality (p-value 0.4).

CONCLUSIONS

Definitive circular external fixation is an excellent treatment for acute tibial FRI. Both Ilizarov and hexapod systems offer a very high rate of fracture healing and infection eradication. Although both presented very low radiological post-operative residual deformity, the hexapod system showed less residual coronal translation deformity and better callus quality.

A novel 3D video oculography system for measuring cross-axis vestibulo-ocular reflex

We present a video oculography (VOG) system with 6-degree-of-freedom (6-DOF) mobility for real-time measurements of the binocular 3D eye position of a small animal. A hybrid hexapod that allowed for multi-axis complex motions with the resolution of the microscopic level was used to control the motion of the animal. The instantaneous eyeball movement of the animal was determined based on two approaches: (1) tracking of marker arrays affixed to the cornea; and (2) tracking the pupil outline. The tracking of the eyeball movement and the motion control of the hexapod were implemented with the LabVIEW virtual instruments. Compared with our previous measurements using a servo-motor-based single-axis VOG system, positional error reduced from more than 4% to less than 0.7%. Validation showed that the tracking errors in three rotational axes are less than 2% for the magnitude and less than 5° for the direction angle. The present VOG system is an effective tool for cross-axis 3D vestibulo-ocular reflex study on small animals.

A Robot Mimicking Heart Motions: An Ex-Vivo Test Approach for Cardiac Devices

Purpose

The pre-clinical testing of cardiovascular implants gains increasing attention due to the complexity of novel implants and new medical device regulations. It often relies on large animal experiments that are afflicted with ethical and methodical challenges. Thus, a method for simulating physiological heart motions is desired but lacking so far.

Methods

We developed a robotic platform that allows simulating the trajectory of any point of the heart (one at a time) in six degrees of freedom. It uses heart motion trajectories acquired from cardiac magnetic resonance imaging or accelero-meter data. The rotations of the six motors are calculated based on the input trajectory. A closed-loop controller drives the platform and a graphical user interface monitors the functioning and accuracy of the robot using encoder data.

Results

The robotic platform can mimic physiological heart motions from large animals and humans. It offers a spherical work envelope with a radius of 29 mm, maximum acceleration of 20 m/s² and maximum deflection of ±19° along all axes. The absolute mean positioning error in x-, y- and z-direction is 0.21 ±0.06, 0.31 ±0.11 and 0.17 ±0.12 mm, respectively. The absolute mean orientation error around x-, y- and z-axis (roll, pitch and yaw) is 0.24 ±0.18°, 0.23 ±0.13° and 0.18 ±0.18°, respectively.

Conclusion

The novel robotic approach allows reproducing heart motions with high accuracy and repeatability. This may benefit the device development process and allows re-using previously acquired heart motion data repeatedly, thus avoiding animal trials.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13239-021-00566-3.

Computer-Assisted Gradual Correction of Charcot Foot Deformities: An In-Depth Evaluation of Stage One of a Planned Two-Stage Approach to Charcot Reconstruction

The surgical treatment of Charcot foot is a widely debated topic, with issues ranging from when to operate to how to properly correct a deformity. Historically, correction of a severe deformity was attempted in 1 acute surgical procedure that frequently required open reduction and internal fixation through large incisions. This 1-time procedure would often result in complications including under- or overcorrection of the deformity, neurovascular injury, or incision dehiscence leading to possible soft-tissue infection or osteomyelitis. This retrospective case series aims to evaluate stage 1 of a planned 2-stage approach to Charcot deformity correction, consisting of gradual modification with the use of computer-assisted external fixation. The purpose of using gradual correction was to safely and accurately correct the Meary and calcaneal inclination angles, which were measured using preoperative and postoperative digital radiographs. The procedure was performed on 18 Charcot foot deformities in 18 patients. Each of the feet had a notably significant rocker bottom deformity and most contained an ulceration. Complete ulcer healing was noted in 100% (13/13) of feet with an ulcer, and a statistically significant corrected Meary's (p < .05) and calcaneal inclination angle (p < .05) to within a normal range was achieved in all deformity corrections with few postoperative problems and complications noted. Average patient follow-up was 39.6 months with a minimum of at least 12 months necessary for inclusion in the study. Therefore, gradual Charcot deformity correction through the use of computer-assisted hexapod external fixation, demonstrates safe, accurate, and reproducible characteristics that adequately prepares the lower extremity for stage 2, the implantation of rigid internal fixation.

Accuracy of radiographic measurement techniques for the Taylor spatial frame mounting parameters

Aim

The correction accuracy of the Taylor Spatial Frame (TSF) fixator depends considerably on the precise determination of the mounting parameters (MP). Incorrect parameters result in secondary deformities that require subsequent corrections. Different techniques have been described to improve the precision of MP measurement, although exact calculation is reportedly impossible radiologically. The aim of this study was to investigate the accuracy of intraoperative and postoperative radiographic measurement methods compared to direct MP measurement from TSF bone mounting.

Methods

A tibial Sawbone® model was established with different origins and reference ring positions. First, reference MPs for each origin were measured directly on the frame and bone using a calibrated, digital vernier calliper. In total 150 MPs measured with three different radiographic measurement techniques were compared to the reference MPs: digital radiographic measurements were performed using soft-copy PACS images without (method A) and with (method B) calibration and calibrated image intensifier images (method C).

Results

MPs measured from a non-calibrated X-ray image (method A) showed the highest variance compared to the reference MPs. A greater distance between the origin and the reference ring corresponded to less accurate MP measurements with method A. However, the MPs measured from calibrated X-ray images (method B) and calibrated image intensifier images (method C) were intercomparable (p = 0.226) and showed only minor differences compared to the reference values but significant differences to method A (p < 0,001).

Conclusion

The results demonstrate that MPs can be accurately measured with radiographic techniques when using calibration markers and a software calibration tool, thus minimizing the source of error and improving the quality of correction.

Management of Osseous Defects of the Tibia Utilizing Orthofix Hexapod Circular External Fixator: A Technique Guide-An Orthoplastic Approach for Combined Soft Tissue and Osseous Defects

Malunions, nonunions, avascular necrosis, neoplasms, and osteomyelitis of the tibia can be difficult limb salvage cases to manage, especially when large bone defects are present. This article aims to demonstrate the orthoplastic limb salvage options that the authors use with bone transport using the Orthofix TrueLok-Hexapod system (Orthofix Medical Inc, Lewisville, TX, USA).

Improving the accuracy of patient positioning for long-leg radiographs using a Taylor Spatial Frame mounted rotation rod

INTRODUCTION

Long-leg radiographs are used to plan and supervise the correction of bone deformity in patients treated with the Taylor Spatial Frame (TSF). Often radiographs are performed with malpositioning of the limb leading to wrong alignment measurements. The aim of this retrospective study was to show the usefulness of a simple device which might enhance the reproducibility of limb rotation on long-leg radiographs.

MATERIALS AND METHODS

We included 20 consecutive patients with TSF treatment and at least three long-leg radiographs (4.9 ± 1.3). Eight out of 20 patients received radiographs with the help of a rotation rod (device with two clamps and a carbon tube). It is placed at the most frontal tab of the reference ring while conducting the radiograph. By this means, limb rotation can be controlled. To show the usefulness of this device, two observers measured the relation of the distances between the middle of the reference ring to the medial and lateral fourth hole on the reference ring (TSF-RR). The standard deviation and range of the TSF-RR of all radiographs for each patient was calculated and compared between patients without and with the rotation rod.

RESULTS

The standard deviations of TSF-RR in patients without the rotation rod was significantly higher compared to patients with rotation rod (observer 1: p = 0.0228, observer 2: p = 0.0038). Also, the range of the TSF-RR within one patient is significant higher (observer 1: p = 0.0279, observer 2: p = 0.0038) in patients without the rotation rod compared to patients with the rotation rod.

CONCLUSIONS

The variability of rotation on radiographs was lower with the rotation rod. Therefore, more reproducible and better comparable radiographs can be conducted. Radiologic exposure might be reduced as repetition of wrongly positioned limbs on radiographs are less frequent.

Complications associated with hexapod circular fixation for acute fractures of the tibia diaphysis: A retrospective descriptive study at a high volume trauma centre

The use of hexapod circular external fixation in acute tibia fracture care is increasing as more general orthopaedic surgeons are gaining expertise with the use of this treatment modality. Limited data is currently available on the complications that may be encountered with this treatment strategy.

AIM

To review the complications and outcomes of acute diaphyseal tibia fractures definitively treated with hexapod circular external fixation at a high volume orthopaedic trauma centre.

METHODS

Retrospective review of clinical and radiological data of adult patients with acute diaphyseal tibia fractures treated with hexapod external fixation between 2012 and 2015 at a single centre.

RESULTS

A total of 102 diaphyseal fractures were definitively treated with hexapod circular external fixation. Union was achieved in 101 cases with an average time to union of 25.6 weeks. Complications included pin site infection (56%); wound complications (19.67%); osteitis (11.76%); malunion (15.69%) and knee and ankle joint contractures (31.32%).

CONCLUSION

Hexapod circular external fixation as definitive treatment of for diaphyseal tibia fractures demonstrates an excellent union rate with acceptable time to union. Complications rates are comparable to that of all fine wire circular fixators. Malalignment in is however a concern, considering that this device enables the surgeon to achieve accurate alignment through gradual deformity correction aided by computer software.

Investigating the vestibular system using modern imaging techniques-A review on the available stimulation and imaging methods

The vestibular organs, located in the inner ear, sense linear and rotational acceleration of the head and its position relative to the gravitational field of the earth. These signals are essential for many fundamental skills such as the coordination of eye and head movements in the three-dimensional space or the bipedal locomotion of humans. Furthermore, the vestibular signals have been shown to contribute to higher cognitive functions such as navigation. As the main aim of the vestibular system is the sensation of motion it is a challenging system to be studied in combination with modern imaging methods. Over the last years various different methods were used for stimulating the vestibular system. These methods range from artificial approaches like galvanic or caloric vestibular stimulation to passive full body accelerations using hexapod motion platforms, or rotatory chairs. In the first section of this review we provide an overview over all methods used in vestibular stimulation in combination with imaging methods (fMRI, PET, E/MEG, fNIRS). The advantages and disadvantages of every method are discussed, and we summarize typical settings and parameters used in previous studies. In the second section the role of the four imaging techniques are discussed in the context of vestibular research and their potential strengths and interactions with the presented stimulation methods are outlined.

External fixation of the lower extremities: Biomechanical perspective and recent innovations

The concept of supporting fractured long bones externally with mechanical fixation has been evidentially applied for over 2000 years, and since been expanded on in the mid-19th century by percutaneous bone fixation. Surgical techniques, external fixator systems, and materials have made continued progress since. The benefits of traditional external fixation have been enhanced in recent years with the introduction of hexapod-style fixators, innovative configurations, and pin modifications, among other things. It is generally agreed upon that biomechanical testing of advancements in external fixation must be inclusive of transverse or torsional loading to simulate construct behaviour in realistic scenarios. Biomechanical studies indicate that hexapod-style fixators show comparable axial stiffness to Ilizarov-style systems and improved performance under torsional and transverse forces. The addition of configuration elements to fixators, inclusion of certain carbon fibre chemical compositions, and techniques intended to augment ring thickness have also been investigated, in hopes of increasing construct stiffness under loading. Novel external fixators attempt to broaden their applications by rethinking bone mounting mechanisms and either expanding on or simplifying the implementation of 3D bone segment transport for corrective osteotomy. Older and seemingly unconventional fixation techniques are being rediscovered and evolved further in order to increase patient comfort by improving everyday usability. The development of new pin coatings can potentially enhance the pin-bone interface while lowering infection rates typically expected at thicker soft tissue envelopes. Although complication, malunion, and nonunion rates have decreased over the past 50 years, the clinical results of external fixation today can still be optimized. Unsatisfactory healing in the lower extremities has especially been reported at locations such as the distal tibia; however, advancements such as osteoinductive growth hormone treatment may provide improved results. With the current progression of technology and digitization, it is only a matter of time before 'smart', partly-autonomous external fixation systems enter the market. This review article will provide a versatile overview of biomechanically proven fixator configurations and some carefully selected innovative systems and techniques that have emerged or been established in the past two decades.

Design of a six-DOF motion tracking system based on a Stewart platform and ball-and-socket joints

This paper presents a six degree-of-freedom (DOF) real-time motion tracking system of measuring the position and the orientation for industrial robots in three-dimensional (3D) space. The proposed system is based on a typical Stewart platform design and utilizes six low-cost displacement sensors to monitor the motion of the Stewart platform. The advantage of the proposed system is its simple calibration and easy accessibility; the magnetic ball-and-socket joints used for rotational joints. With special measurement tools, the center of rotation of all twelve joints can be measured in 3D space at a glance. Following more than fifty measurements, the average root mean square (RMS) position accuracy error of the proposed device is less than 0.186 mm and the average of angular accuracy error is less than 0.160 °, making it suitable for monitoring the performance of industrial robot. A commercial robot is also tested by the proposed system to verify its usefulness.

The Gradual and Acute Correction of Equinus Using External Fixation

Equinus is one of the most common deformities noted in foot and ankle biomechanics that, at times, if not identified and managed properly may lead to significant lower extremity pathology. With that being said, this deformity is also one that may be both underdiagnosed and undertreated. Treatment for equinus can range from conservative therapy to more aggressive surgical therapy. The purpose of this article is to review the clinical workup to properly identify the deformity and to explore the various treatment options for its timely management, which include gradual or acute correction of equinus using external fixation.

Lengthen, Alignment, and Beam Technique for Midfoot Charcot Neuroarthropathy

Charcot neuroarthropathy is a disabling pathology in the foot and ankle. Midfoot Charcot is most common and results in progressive deformity. We describe a 2-step approach to surgical reconstruction, referred to as the lengthen, alignment, and beam technique. There is an initial surgery involving acute equinus correction through Achilles tendon lengthening and gradual correction with hexapod external fixation to align the deformity, followed by minimally invasive medial and lateral column beaming. This surgical protocol allows for adequate reduction of deformity. The second stage allows for rigid intramedullary fixation extending beyond the pathologic joints via a minimally invasive technique.

Preliminary results using patient-specific 3d printed models to improve preoperative planning for correction of post-traumatic tibial deformities with circular frames

BACKGROUND

Preoperative planning for circular external fixators is considered vital towards achieving the best results for complex post-traumatic tibial deformities, and patient-specific 3D printed (3DP) models were used here as a planning aid. The main goal was to investigate the fidelity of the preoperative planning process, by assessing the potential to reduce operative time and determining the need to adjust pre-constructed frames intra-operatively.

PATIENTS AND METHODS

Nine patients (10 limbs) underwent treatment for post-traumatic tibial complications using circular external fixation. These were compared to 10 similar cases where a 3DPM was not used as a pre-operative planning aide (Control group). Patient-specific models of affected bones were printed, and preoperative planning was performed using conventional techniques and Hexapod-assisted software. Detailed planning in a virtual procedure determined osteotomy levels and identified sites for wires and half-pins. The prototype of the external fixator was locked in this optimized configuration, removed from the model, and sterilized prior to the actual procedure.

RESULTS

Nine patients with 10 limbs were treated for complications following tibial fractures. Seven were infected non-unions, and three cases were malunions. For all cases a CT based 3DP model of the full tibia was used in the preoperative planning stage. Image analysis required a mean of 1.7 h, with an average of 14.9 h to 3D print each model. In the control group (without a 3D model), the mean surgical time was 329 min (180-680). The mean surgical time in the 3DPM group was only 172.4 min (72-240), (p = 0.024), reducing the surgery time by 48%. For the 3DPM group it was not necessary to modify the preassembled frame in any case, while in the Control group, the pre-constructed frame required intra-operative modifications in 8 of the 10 cases (p = 0.0007).

CONCLUSION

Using patient-specific 3D models has allowed us to carry out meticulous preoperative planning sessions, eliminating the need to modify or alter the frame assembly in the operating room, saving substantial surgical time and enabling a more precise design of the apparatus. This was especially useful in multiplanar deformities and for the spatial configuration of the foot support, talus ring, and ankle ring.

Functional outcomes of the failed plate fixation in distal tibial fractures salvaged by hexapod external fixator

PURPOSE

The purpose of this study was to evaluate the clinical and functional outcomes of failed plate fixation in distal tibia fractures salvaged with hexapod circular fixators.

MATERIALS AND METHODS

The database of a specialized limb reconstruction center was searched for all patients with failed plate fixation undergoing limb reconstruction with a circular external fixator between 2008 and 2017. Patients between the ages of 18-65 years, with a symptomatic distal tibia malunion or non-union following plate and screw fixation were included. The SF-12 and Foot Function Index (FFI) scoring systems were used to measure clinical and functional outcomes.

RESULTS

Ten patients with a mean age of 38 ± 13 years met the inclusion criteria. Seven patients had an infected non-union, two hypertrophic non-unions, and one a malunion. The mean follow-up was 41.7 ± 28.3 months. The mean duration of external fixation was 232.9 ± 146.6 days. The SF-12 demonstrated a mean score of 49.4 ± 7.7 for the physical component and a mean score of 55.3 ± 8.1 for the mental component. Five patients (50%) scored above 45 points for the SF12 physical component, and nine patients (90%) scored above 45 points for the mental component, indicating good outcome can be achieved. The mean FFI score was 24.9 ± 19.9, and six patients had a score below 14 points (good outcome). Radiological union was observed in all 10 patients at a mean of 29 ± 14 months.

CONCLUSIONS

The results of this study suggest that hexapod circular external fixation is an attractive surgical alternative for the treatment of failed plate fixation of distal tibial fractures, and can reliably achieve bony union and result in very satisfactory clinical outcomes.

LEVEL OF EVIDENCE

Level IV case series.

The silhouette technique: improving post-operative radiographs for planning of correction with a hexapod external fixator

Correction of deformity of a bone through use of a hexapod external fixator requires clear definition of the relationship between the bone and the frame. Achieving adequate orthogonal calibrated radiographs for this aim, with minimum X-ray exposure, can prove a challenge in the radiography suite. We describe a simple technique for obtaining adequate imaging, without the use of additional equipment. Introduction of the technique to our department has demonstrated an improvement in the adequacy of planning radiographs and a reduction in the requirement for repeat imaging.

Femoral locking plate failure salvaged with hexapod circular external fixation: a report of two cases

Femoral non-unions are difficult to treat even for the experienced orthopaedic trauma surgeon. If the non-union follows failure of modern stable internal fixation, the complexity of the management is further increased. We report two cases of stiff hypertrophic femoral non-unions after failed locking plate fixation that were successfully treated with a new hexapod circular external fixator. In addition to providing the necessary stability for functional rehabilitation and union, the hexapod circular fixator software allows gradual correction of deformities in order to restore the normal mechanical alignment of the limb.