A Neoponera villosa (Fabricius, 1804) Worker Pupa with too Many Legs (Hymenoptera: Formicidae).

Several somatic and sexual anomalies such as gynandromorphism and other morphological malformations have been described in ants, but cases of supernumerary legs in natural populations are rare, with only six cases reported to date. Moreover, few cases of abnormalities have been reported for the Ponerinae subfamily, with only three cases of genetic chimeras and five teratological cases worldwide. We report here a new case of teratology in this subfamily, with a seven-legged worker pupa found in a Neoponera villosa colony nesting in an epiphytic tank bromeliad. This is the second case for Mexico of a morphological anomaly in a ponerine ant, but the first report of a teratological case in the subfamily for this country.

A continuous-wave and pulsed X-band electron spin resonance spectrometer operating in ultra-high vacuum for the study of low dimensional spin ensembles.

We report the development of a continuous-wave and pulsed X-band electron spin resonance (ESR) spectrometer for the study of spins on ordered surfaces down to cryogenic temperatures. The spectrometer operates in ultra-high vacuum and utilizes a half-wavelength microstrip line resonator realized using epitaxially grown copper films on single crystal Al2O3 substrates. The one-dimensional microstrip line resonator exhibits a quality factor of more than 200 at room temperature, close to the upper limit determined by radiation losses. The surface characterizations of the copper strip of the resonator by atomic force microscopy, low-energy electron diffraction, and scanning tunneling microscopy show that the surface is atomically clean, flat, and single crystalline. Measuring the ESR spectrum at 15 K from a few nm thick molecular film of YPc2, we find a continuous-wave ESR sensitivity of 2.6 × 1011 spins/G · Hz1/2, indicating that a signal-to-noise ratio of 3.9 G · Hz1/2 is expected from a monolayer of YPc2 molecules. Advanced pulsed ESR experimental capabilities, including dynamical decoupling and electron-nuclear double resonance, are demonstrated using free radicals diluted in a glassy matrix.

Proteomic and phosphoproteomic characterization of cardiovascular tissues after long term exposure to simulated space radiation.

Introduction: It may take decades to develop cardiovascular dysfunction following exposure to high doses of ionizing radiation from medical therapy or from nuclear accidents. Since astronauts may be exposed continually to a complex space radiation environment unlike that experienced on Earth, it is unresolved whether there is a risk to cardiovascular health during long-term space exploration missions. Previously, we have described that mice exposed to a single dose of simplified Galactic Cosmic Ray (GCR5-ion) develop cardiovascular dysfunction by 12 months post-radiation. Methods: To investigate the biological basis of this dysfunction, here we performed a quantitative mass spectrometry-based proteomics analysis of heart tissue (proteome and phosphoproteome) and plasma (proteome only) from these mice at 8 months post-radiation. Results: Differentially expressed proteins (DEPs) for irradiated versus sham irradiated samples (fold-change ≥1.2 and an adjusted p-value of ≤0.05) were identified for each proteomics data set. For the heart proteome, there were 87 significant DEPs (11 upregulated and 76 downregulated); for the heart phosphoproteome, there were 60 significant differentially phosphorylated peptides (17 upregulated and 43 downregulated); and for the plasma proteome, there was only one upregulated protein. A Gene Set Enrichment Analysis (GSEA) technique that assesses canonical pathways from BIOCARTA, KEGG, PID, REACTOME, and WikiPathways revealed significant perturbation in pathways in each data set. For the heart proteome, 166 pathways were significantly altered (36 upregulated and 130 downregulated); for the plasma proteome, there were 73 pathways significantly altered (25 upregulated and 48 downregulated); and for the phosphoproteome, there were 223 pathways significantly affected at 0.1 adjusted p-value cutoff. Pathways related to inflammation were the most highly perturbed in the heart and plasma. In line with sustained inflammation, neutrophil extracellular traps (NETs) were demonstrated to be increased in GCR5-ion irradiated hearts at 12-month post irradiation. NETs play a fundamental role in combating bacterial pathogens, modulating inflammatory responses, inflicting damage on healthy tissues, and escalating vascular thrombosis. Discussion: These findings suggest that a single exposure to GCR5-ion results in long-lasting changes in the proteome and that these proteomic changes can potentiate acute and chronic health issues for astronauts, such as what we have previously described with late cardiac dysfunction in these mice.

Midterm outcomes of total hip arthroplasty after internal hemipelvectomy and iliofemoral arthrodesis.

BACKGROUND AND OBJECTIVES: Recent studies have reported acceptable outcomes after arthrodesis takedown and conversion to total hip arthroplasty (THA); however, there are no reports on outcomes after oncologic resection, which are inherently complex and may portend poorer outcomes. The purpose of this study was to examine the surgical and functional outcomes of patients who underwent prior hemipelvectomy for tumor resection and were later converted to THA. METHODS: All patients who had prior iliofemoral arthrodesis after oncologic resection that were later converted to THA at a single institution were examined. Charts were reviewed for demographic information, operative information, functional outcomes, and complications/reoperations. RESULTS: All three patients in this study were males who underwent internal hemipelvectomies for chondrosarcoma. Patients were converted to THA at a mean of 26 years after arthrodesis. Mean follow-up after conversion to THA was 7.4 years. During this follow-up period, two of the three patients required revision surgery. At last follow-up, the mean Harris Hip Score was 81 and the mean Mayo Hip Score was 67, and all patients were ambulatory without significant pain. CONCLUSIONS: Overall, patients who undergo iliofemoral arthrodesis after oncologic hemipelvectomy and are later converted to THA can expect to have a reasonable outcome, despite a high rate of complications and revision surgery.

Cohabitation with aggressive hosts: description of a new microhisterid species in nests of a ponerine ant with ecological notes.

A new clown beetle species, Bacanius neoponerae, is described from Mexican nests of the arboreal ponerine ant Neoponera villosa found in the tank bromeliad Aechmea bracteata. Adult beetles were found in brood chambers or inner refuse piles, but also outside the ant nests, in decaying organic matter between the bromeliad leaves. No direct interactions between ants and microhisterid beetles could be observed. Several lines of evidence suggest a close relationship either with the ants, specific microhabitats within the ant nests or the bromeliads. Sample site elevation, colony size, monthly rainfall and collecting site were the main variables predicting the association. Almost half of the N. villosa colonies were associated with the microhisterids, and larger colonies favored their presence, especially during the driest months of the year. Two specimens were found in a nest of another ant species, Camponotus atriceps, also inhabiting A. bracteata. The new species is the seventh of the genus Bacanius reported from Mexico. This is the second time a species of this genus is associated with ants, and the fourth record of a histerid beetle cohabiting with ponerine ants. The small size of these beetles and their very protective body structure may facilitate their cohabitation with such aggressive hosts.

Video analysis of ex vivo beating hearts during preservation on the TransMedics® organ care system.

Background: Reliable biomarkers for assessing the viability of the donor hearts undergoing ex vivo perfusion remain elusive. A unique feature of normothermic ex vivo perfusion on the TransMedics® Organ Care System (OCS™) is that the donor heart is maintained in a beating state throughout the preservation period. We applied a video algorithm for an in vivo assessment of cardiac kinematics, video kinematic evaluation (Vi.Ki.E.), to the donor hearts undergoing ex vivo perfusion on the OCS™ to assess the feasibility of applying this algorithm in this setting. Methods: Healthy donor porcine hearts (n = 6) were procured from Yucatan pigs and underwent 2 h of normothermic ex vivo perfusion on the OCS™ device. During the preservation period, serial high-resolution videos were captured at 30 frames per second. Using Vi.Ki.E., we assessed the force, energy, contractility, and trajectory parameters of each heart. Results: There were no significant changes in any of the measured parameters of the heart on the OCS™ device over time as judged by linear regression analysis. Importantly, there were no significant changes in contractility during the duration of the preservation period (time 0-30 min, 918 ± 430 px/s; time 31-60 min, 1,386 ± 603 px/s; time 61-90 min, 1,299 ± 617 px/s; time 91-120 min, 1,535 ± 728 px/s). Similarly, there were no significant changes in the force, energy, or trajectory parameters. Post-transplantation echocardiograms demonstrated robust contractility of each allograft. Conclusion: Vi.Ki.E. assessment of the donor hearts undergoing ex vivo perfusion is feasible on the TransMedics OCS™, and we observed that the donor hearts maintain steady kinematic measurements throughout the duration.

Ex Vivo Gene Delivery to Porcine Cardiac Allografts Using a Myocardial-Enhanced Adeno-Associated Viral Vector.

Transplantation, the gold standard intervention for organ failure, is a clinical field that is ripe for applications of gene therapy. One of the major challenges in applying gene therapy to this field is the need for a method that achieves consistent and robust gene delivery to allografts. Normothermic ex vivo perfusion is a growing organ preservation method and a device for cardiac preservation was recently approved by the Food and Drug Administration (FDA) (Organ Care System, OCS™; TransMedics, Inc., Andover, MA); this device maintains donor hearts in a near physiologic state while they are transported from the donor to the recipient. This study describes the administration of recombinant adeno-associated viral vectors (rAAVs) during ex vivo normothermic perfusion for the delivery of transgenes to porcine cardiac allografts. We utilized a myocardial-enhanced AAV3b variant, SASTG, assessing its transduction efficiency in the OCS perfusate relative to other AAV serotypes. We describe the use of normothermic ex vivo perfusion to deliver SASTG carrying the Firefly Luciferase transgene to porcine donor hearts in four heterotopic transplant procedures. Durable and dose-dependent transgene expression was achieved in the allografts in 30 days, with no evidence of off-target transgene expression. This study demonstrates the feasibility and efficiency of delivering genes to a large animal allograft utilizing AAV vectors during ex vivo perfusion. These findings support the idea of gene therapy interventions to enhance transplantation outcomes.

First Record of the Elusive Ant Parasitoid Horismenus floridensis (Hymenoptera: Eulophidae) in Mexico and New Association with an Ant Host.

Most eulophid wasps are primary parasitoids, mainly of endophytic insect larvae (Diptera, Coleoptera, Lepidoptera, Hymenoptera, Hemiptera, and Thysanoptera), but can also attack spider eggs, gall-forming mites, or nematodes. A few species are known to parasitize ants. Here we report on the occurrence of Horismenus floridensis (Schauff and Boucek) attacking Camponotus atriceps (Smith) in southern Mexico (Campeche), expanding the distribution for this eulophid species and the range of its potential hosts. We also provide an updated list of the Horismenus Walker species found in Mexico, which currently includes 21 identified species. This is the second host ant ever recorded for H. floridensis and the first reliable record of C. atriceps as a host for this eulophid wasp. The first host ant reported from Florida 35 years ago was the closely related valid species, C. floridanus (Buckley), erroneously synonymized at that time with C. atriceps (formerly, C. abdominalis (Fabricius)).

Pollination service provided by honey bees to buzz-pollinated crops in the Neotropics.

Generalist honey bees grant significant pollination services worldwide. Although honey bees can provide compensatory pollination services, their service to buzz-pollinated crops, compared to specialized pollinators, is not clear. In this study, we assessed the contribution of Africanized honey bees (AHB) and native sonicating bees (NBZ) to the pollination of eggplant (Solanum melongena) and annatto (Bixa orellana) in Yucatan, Mexico, one of the largest producers of these crops in the Americas and a region with one of the largest densities of honey bees in the world. We first compared the relative frequency and abundance of both bee types on flowers of both crops. Secondly, we controlled access to flowers to compare the number and weight of fruit and number of seed produced after single visits of AHB and native bees. For a better assessment of pollination services, we evaluated the productivity of individual flowers multiply visited by AHB. The results were compared against treatments using pollinator-excluded flowers and flowers that were supplied with additional pollen, which allowed an overall measure of pollination service provision (PSP). Our results showed that AHB were the predominant flower visitors in both crops and that were poorly efficient on individual visits. Notably, fruit quantity and seed number increased concomitantly with the number of AHB visits per flower on eggplant, but not on annatto. Estimation of PSP revealed no pollination deficit on eggplant but that a deficit existed on the pollination services to annatto. We found that AHB numerical predominance compensates their poor individual performance and can complement the services of native bees on eggplant, but not on annatto. We discuss possible explanations and implications of these results for buzz-pollinated crops in the neotropics an area with little assessment of pollination services and a high density of honey bees.

Transvenous Endomyocardial Biopsy Technique for Intra-abdominal Heterotopic Cardiac Grafts.

The porcine intra-abdominal heterotopic heart transplantation model allows for the assessment of immunologic effects on cardiac transplantation without relying on the allograft to maintain hemodynamic support for the animal. Historically, allograft function and histology is monitored by physical exam, echocardiogram evaluation, percutaneous core biopsy, and open biopsy. We performed transvenous endomyocardial biopsies in three pigs that had undergone heterotopic heart implantation. We describe the procedure to be feasible and reproducible, and that histologic results from these biopsies correlated with those from corresponding tissue collected by surgical dissection at the time of allograft explantation. The ability to perform endomyocardial biopsies in the heterotopic heart transplantation model allows for serial non-invasive monitoring of allograft histology.

Development of a scanning tunneling microscope for variable temperature electron spin resonance.

Recent advances in improving the spectroscopic energy resolution in scanning tunneling microscopy (STM) have been achieved by integrating electron spin resonance (ESR) with STM. Here, we demonstrate the design and performance of a homebuilt STM capable of ESR at temperatures ranging from 1 to 10 K. The STM is incorporated with a homebuilt Joule-Thomson refrigerator and a two-axis vector magnet. Our STM design allows for the deposition of atoms and molecules directly into the cold STM, eliminating the need to extract the sample for deposition. In addition, we adopt two methods to apply radio-frequency (RF) voltages to the tunnel junction: the early design of wiring to the STM tip directly and a more recent idea to use an RF antenna. Direct comparisons of ESR results measured using the two methods and simulations of electric field distribution around the tunnel junction show that, despite their different designs and capacitive coupling to the tunnel junction, there is no discernible difference in the driving and detection of ESR. Furthermore, at a magnetic field of ∼1.6 T, we observe ESR signals (near 40 GHz) sustained up to 10 K, which is the highest temperature for ESR-STM measurement reported to date, to the best of our knowledge. Although the ESR intensity exponentially decreases with increasing temperature, our ESR-STM system with low noise at the tunnel junction allows us to measure weak ESR signals with intensities of a few fA. Our new design of an ESR-STM system, which is operational in a large frequency and temperature range, can broaden the use of ESR spectroscopy in STM and enable the simple modification of existing STM systems, which will hopefully accelerate a generalized use of ESR-STM.

Effects of terrestrial dissolved organic matter on a bloom of the toxic cyanobacteria, Raphidiopsis raciborskii.

The concentration of coloured terrestrial dissolved organic matter (tDOM) from vegetation appears to be increasing in lakes in some regions of the world, leading to the term brownification. The light attenuating effect of coloured tDOM on phytoplankton growth has been a major focus of attention, but the phytotoxic effects of tDOM, particularly on cyanobacterial blooms, are less well understood. This mesocosm study tested whether coloured tDOM, leached from the leaves of a Eucalyptus tree species, inhibited a naturally occurring bloom of the toxic cyanobacterium, Raphidiopsis raciborskii, in a reservoir over a 10 day period. The study found that tDOM leachate, measured as dissolved organic carbon (DOC), inhibited photosynthesis and growth of both R. raciborskii, as well as species present at lower densities, i.e. other cyanobacteria and diatoms. However, the effect was greater at higher tDOM input loads. The photosynthetic yield (Fv/Fm) of cyanobacteria decreased rapidly in treatments with 5.9 and 25 mg L-1 DOC addition, compared to the control (reservoir water with background DOC concentration of 6.85 ± 1.09 mg L-1). tDOM had no measurable effect in the 2 and 3.3 mg L-1 DOC addition treatments. By day 5, cell densities of cyanobacteria, including R. raciborskii, and diatoms, in treatments with 5.9 and 25 mg L-1 DOC addition were significantly lower than the control with no tDOM addition, and this effect continued throughout the experiment. This is despite the leachate addition increasing phosphate concentrations which counteracted the low background concentrations of phosphate. Light attenuation and dissolved oxygen (DO) levels were also affected by the tDOM addition, but were only significantly lower in the 25 mg L-1 DOC treatment compared with the control. DOC, dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) concentrations all decreased in the tDOM addition treatments over the first 3 days, as the microbial cell densities increased. The components of the tDOM that decreased over time were determined by 1H NMR spectroscopy in the 25 mg L-1 DOC treatment. After 5 d, the relative concentrations of fatty acids, sugars and gallic acid decreased by around 60%, while concentrations of flavonoids and myo-inositol decreased by 45 and 35% respectively. This study suggests that phytotoxic compounds in tDOM can suppress cyanobacterial blooms, despite the increased nutrient inputs. This has implications for predicting the future likelihood of cyanobacterial blooms in lakes and reservoirs with climate-change driven changes in flow events, and other changes in the amount and types of vegetation cover. Revegetation of riparian zones, resulting in increased tDOM into waterways, may also be beneficial in reducing cyanobacterial blooms.

Late onset cardiovascular dysfunction in adult mice resulting from galactic cosmic ray exposure.

The complex and inaccessible space radiation environment poses an unresolved risk to astronaut cardiovascular health during long-term space exploration missions. To model this risk, healthy male c57BL/6 mice aged six months (corresponding to an astronaut of 34 years) were exposed to simplified galactic cosmic ray (GCR5-ion; 5-ion sim) irradiation at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratories (BNL). Multi-modal cardiovascular functional assessments performed longitudinally and terminally revealed significant impairment in cardiac function in mice exposed to GCR5-ion compared to unirradiated controls, gamma irradiation, or single mono-energetic ions (56Fe or 16O). GCR5-ion-treated mice exhibited increased arterial elastance likely mediated by disruption of elastin fibers. This study suggests that a single exposure to GCR5-ion is associated with deterioration in cardiac structure and function that becomes apparent long after exposure, likely associated with increased morbidity and mortality. These findings represent important health considerations when preparing for successful space exploration.

A Porcine Heterotopic Heart Transplantation Protocol for Delivery of Therapeutics to a Cardiac Allograft.

Cardiac transplantation is the gold standard treatment for end-stage heart failure. However, it remains limited by the number of available donor hearts and complications such as primary graft dysfunction and graft rejection. The recent clinical use of an ex vivo perfusion device in cardiac transplantation introduces a unique opportunity for treating cardiac allografts with therapeutic interventions to improve function and avoid deleterious recipient responses. Establishing a translational, large-animal model for therapeutic delivery to the entire allograft is essential for testing novel therapeutic approaches in cardiac transplantation. The porcine, heterotopic heart transplantation model in the intraabdominal position serves as an excellent model for assessing the effects of novel interventions and the immunopathology of graft rejection. This model additionally offers long-term survival for the pig, given that the graft is not required to maintain the recipient's circulation. The aim of this protocol is to provide a reproducible and robust approach for achieving ex vivo delivery of a therapeutic to the entire cardiac allograft prior to transplantation and provide technical details to perform a survival heterotopic transplant of the ex vivo perfused heart.

Primary and revision total hip arthroplasty with uncemented acetabular components in patients with Paget's disease.

INTRODUCTION: Paget's disease affects 3-4% of the population; however, literature describing outcomes of total hip arthroplasty (THA) in this population are limited. Given the known concerns with bleeding, heterotopic ossification (HO), and component loosening, we describe our results with primary and revision THAs in Paget's disease with emphasis on implant survivorship, radiographic results, and clinical outcomes. METHODS: We identified 25 THAs performed with contemporary uncemented acetabular components in patients with Paget's disease from 1999 to 2014. Mean age and follow-up were 78 and 7 years. RESULTS: In primary THAs, survivorship free from aseptic acetabular and femoral loosening was 100% and 94% at 8 years. 7 patients (41%) received blood transfusions. HO was seen in 9 (53%). Mean Harris Hip Score (HHS) improved from 49 to 76. In revision THAs, survivorship free from acetabular and/or femoral aseptic loosening was 100% at 5 years. 3 patients (38%) received a transfusion. HO was seen in 5 (63%). Mean HHS improved from 52 to 77. There were no radiographic signs of aseptic loosening among unrevised cases in either group. DISCUSSION: Our investigation demonstrates that concerns with acetabular fixation in Paget's disease have been mitigated with contemporary uncemented acetabular components. Complications previously noted, namely intraoperative bleeding and HO, continue to be of concern.

A new ant-butterfly symbiosis in the forest canopy fills an evolutionary gap.

Myrmecophilous butterflies can establish complex symbiotic relationships with ants. A caterpillar wandering among the brood of the aggressive ponerine ant Neoponera villosa was found inside the core of a nest built in the myrmecophytic bromeliad Aechmea bracteata. This is the first caterpillar found living inside a ponerine ant nest. Its DNA barcode was sequenced, and an integrative approach was used to identify it as Pseudonymphidia agave, a poorly known member of the subtribe Pachythonina in the riodinid tribe Nymphidiini. The cuticle of the tank-like caterpillar lacks projections or tubercles and is covered dorsally by specialized flat setae that form an armor of small plates. Ant-organs potentially related to caterpillar-ant signaling, such as perforated cupola organs and tentacle nectary organs, are present. These morphological traits, together with evidence of social integration (direct contact with host brood, protective morphology, slow movement, no host aggressiveness), suggest that P. agave is a symbiotic, social parasite of N. villosa, preying on its host brood. However, several knowledge gaps remain, including oviposition site, dependence on bromeliad association, steps to colony integration, and larval diet through development. Carnivory has been reported in all known members of the subtribe Pachythonina (caterpillars prey on honeydew-producing hemipterans) suggesting a shift to myrmecophagy inside the ant nests as a possible evolutionary transition.

A conceptual model of nitrogen dynamics for the Great Barrier Reef catchments.

Nitrogen (N) from anthropogenic sources has been identified as a major pollutant of the Great Barrier Reef (GBR), Australia. We developed a conceptual framework to synthesise and visualise the fate and transport of N from the catchments to the sea from a literature review. The framework was created to fit managers and policymakers' requirements to reduce N in the GBR catchments. We used this framework to determine the N stocks and transformations (input, sources, and outputs) for ecosystems commonly found in the GBR: rainforests, palustrine wetlands, lakes, rivers (in-stream), mangroves and seagrasses. We included transformations of N such as nitrogen fixation, nitrification, denitrification, mineralisation, anammox, sedimentation, plant uptake, and food web transfers. This model can be applied to other ecosystems to understand the transport and fate of N within and between catchments. Importantly, this approach can guide management actions that attenuate N at different scales and locations within the GBR ecosystems. Finally, when combined with local hydrological modelling, this framework can be used to predict outcomes of management activities.

Comparison of free vascularized fibular flaps and allograft fibular strut grafts to supplement spinopelvic reconstruction for sacral malignancies.

AIMS: Orthopaedic and reconstructive surgeons are faced with large defects after the resection of malignant tumours of the sacrum. Spinopelvic reconstruction is advocated for resections above the level of the S1 neural foramina or involving the sacroiliac joint. Fixation may be augmented with either free vascularized fibular flaps (FVFs) or allograft fibular struts (AFSs) in a cathedral style. However, there are no studies comparing these reconstructive techniques. METHODS: We reviewed 44 patients (23 female, 21 male) with a mean age of 40 years (SD 17), who underwent en bloc sacrectomy for a malignant tumour of the sacrum with a reconstruction using a total (n = 20), subtotal (n = 2), or hemicathedral (n = 25) technique. The reconstructions were supplemented with a FVF in 25 patients (57%) and an AFS in 19 patients (43%). The mean length of the strut graft was 13 cm (SD 4). The mean follow-up was seven years (SD 5). RESULTS: There was no difference in the mean age, sex, length of graft, size of the tumour, or the proportion of patients with a history of treatment with radiotherapy in the two groups. Reconstruction using an AFS was associated with nonunion (odds ratio 7.464 (95% confidence interval (CI) 1.77 to 31.36); p = 0.007) and a significantly longer mean time to union (12 months (SD 3) vs eight (SD 3); p = 0.001) compared with a reconstruction using a FVF. Revision for a pseudoarthrosis was more likely to occur in the AFS group compared with the FVF group (hazard ratio 3.84 (95% CI 0.74 to 19.80); p = 0.109); however, this was not significant. Following the procedure, 32 patients (78%) were mobile with a mean Musculoskeletal Tumor Society Score 93 of 52% (SD 24%). There was a significantly higher mean score in patients reconstructed with a FVF compared with an AFS (62% vs 42%; p = 0.003). CONCLUSION: Supplementation of spinopelvic reconstruction with a FVF was associated with a shorter time to union and a trend towards a reduced risk of hardware failure secondary to nonunion compared with reconstruction using an AFS. Spinopelvic fixation supplemented with a FVF is our preferred technique for reconstruction following resection of a sacral tumour. Cite this article: Bone Joint J 2021;103-B(8):1414-1420.

Outcome of Sacropelvic Resection and Reconstruction Based on a Novel Classification System.

BACKGROUND: Sacral tumor resections require a multidisciplinary approach to achieve a cure and a functional outcome. Currently, there is no accepted classification system that provides a means to communicate among the multidisciplinary teams in terms of approach, osseous resection, reconstruction, and acceptable functional outcome. The purpose of this study was to report the outcome of sacral tumor resection based on our classification system. METHODS: In this study, 196 patients (71 female and 125 male) undergoing an oncologic en bloc sacrectomy were reviewed. The mean age (and standard deviation) was 49 ± 16 years, and the mean body mass index was 27.2 ± 6.4 kg/m. The resections included 130 sarcomas (66%). The mean follow-up was 7 ± 5 years. RESULTS: Resections included total sacrectomy (Type 1A: 20 patients [10%]) requiring reconstruction, subtotal sacrectomy (Type 1B: 5 patients [3%]) requiring reconstruction, subtotal sacrectomy (Type 1C: 104 patients [53%]) not requiring reconstruction, hemisacrectomy (Type 2: 29 patients [15%]), external hemipelvectomy and hemisacrectomy (Type 3: 32 patients [16%]), total sacrectomy and external hemipelvectomy (Type 4: 5 patients [3%]), and hemicorporectomy (Type 5: 1 patient [1%]). The disease-specific survival was 66% at 5 years and 52% at 10 years. Based on the classification, the 5-year disease-specific survival was 34% for Type 1A, 100% for Type 1B, 71% for Type 1C, 65% for Type 2, 57% for Type 3, 100% for Type 4, and 100% for Type 5 (p < 0.001). Tumor recurrence occurred in 67 patients, including isolated local recurrence (14 patients), isolated metastatic disease (31 patients), and combined local and metastatic disease (22 patients). At 5 years, the local recurrence-free survival was 77% and the metastasis-free survival was 68%. Complications occurred in 153 patients (78%), most commonly wound complications (95 patients [48%]). Following the procedure, 154 patients (79%) were ambulatory, and the mean Musculoskeletal Tumor Society (MSTS93) score was 60% ± 23%. CONCLUSIONS: Although resections of sacral malignancies are associated with complications, they can be curative in a majority of patients, with a majority of patients ambulatory with an acceptable functional outcome considering the extent of the resection. At our institution, this classification allows for communication between surgical teams and implies a surgical approach, staging, reconstruction, and potential functional outcomes. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.