Embolism After Injection of a Calcium Sulfate Bone Graft Substitute: A Case Report.

CASE: A 66-year-old man presented with new left hip pain after total hip arthroplasty 21 years earlier. Computed tomography imaging revealed massive osteolysis involving the ileum behind the well-fixed acetabular component. The patient was indicated for head and liner exchange with grafting of the osteolytic lesion. Surgery was complicated by cardiopulmonary arrest after injection of a bone graft substitute into the lesion. Despite resuscitation attempts, the patient died. CONCLUSION: Embolism is a rare complication of bone graft substitute injection for pelvic osteolysis. This material can extravasate from bone and deposit in the pulmonary and cerebral microcirculation.

How Has COVID-19 Affected Our Orthopedic Implant Industry Partners? Implications for the Surgeon-Industry Relationship in 2020 and Beyond.

BACKGROUND: The COVID-19 pandemic has had far-reaching societal and financial consequences. The purpose of this study was to evaluate how COVID-19 has affected AAHKS industry partners and the surgeon-industry relationship, emphasizing education, resource allocation, and strategic direction for the second half of 2020. METHODS: AAHKS industry partners were contacted to participate in a blinded survey and optional interview with the AAHKS Industry Relations Committee. Based on the results, a group of AAHKS member surgeons with disparate practice types were asked to postulate on how the COVID-19 pandemic has and will affect their practice and relationship with Industry. RESULTS: AAHKS industry partner responses indicated decreased resource allocation for regional, "other national," and AAHKS annual meetings (67%, 55%, and 30%, respectively). Web-based educational content was expected to increase in 2020 and will likely remain a point of emphasis in 2021 (100% and 70% of responders). For Q3/Q4 2020, a significant emphasis was placed on site of service/outpatient TJA and COVID-19-related safety measures (70% and 90% of responders), as well as increased availability of instrumentation and implants (40% and 60%, respectively). CONCLUSION: The COVID-19 pandemic has altered the orthopedic landscape for the foreseeable future. Survey responses by AAHKS industry partners demonstrate a continued commitment to surgeon education with an increasing shift to a web-based platform. Increased resource allocation for outpatient TJA and COVID-19-related safety measures were significant. Articulating optimal mechanisms to aid industry in supporting surgeons with different practice models to meet demand during the second half of fiscal year 2020 will be critical.

Ocean acidification and the Permo-Triassic mass extinction.

Ocean acidification triggered by Siberian Trap volcanism was a possible kill mechanism for the Permo-Triassic Boundary mass extinction, but direct evidence for an acidification event is lacking. We present a high-resolution seawater pH record across this interval, using boron isotope data combined with a quantitative modeling approach. In the latest Permian, increased ocean alkalinity primed the Earth system with a low level of atmospheric CO2 and a high ocean buffering capacity. The first phase of extinction was coincident with a slow injection of carbon into the atmosphere, and ocean pH remained stable. During the second extinction pulse, however, a rapid and large injection of carbon caused an abrupt acidification event that drove the preferential loss of heavily calcified marine biota.

Cadaveric simulation of a pes cavus foot.

BACKGROUND: The pes cavus deformity has been well described in the literature; relative bony positions have been determined and specific muscle imbalances have been summarized. However, we are unaware of a cadaveric model that has been used to generate this foot pathology. The purpose of this study was to create such a model for future work on surgical and conservative treatment simulation. MATERIALS AND METHODS: We used a custom designed, pneumatically actuated loading frame to apply forces to otherwise normal cadaveric feet while measuring bony motion as well as force beneath the foot. The dorsal tarsometatarsal and the dorsal intercuneiform ligaments were attenuated and three muscle imbalances, each similar to imbalances believed to cause the pes cavus deformity, were applied while bony motion and plantar forces were measured. RESULTS: Only one of the muscle imbalances (overpull of the Achilles tendon, tibialis anterior, tibialis posterior, flexor hallucis longus and flexor digitorum longus) was successful at consistently generating the changes seen in pes cavus feet. This imbalance led to statistically significant changes including hindfoot inversion, talar dorsiflexion, medial midfoot plantar flexion and inversion, forefoot plantar flexion and adduction and an increase in force on the lateral mid- and forefoot. CONCLUSION: We have created a cadaveric model that approximates the general changes of the pes cavus deformity compared to normal feet. These changes mirror the general patterns of deformity produced by several disease mechanisms. CLINICAL RELEVANCE: Future work will entail increasing the severity of the model and exploring various pes cavus treatment strategies.

Disruption of the adenosine deaminase (ADA) gene using a dicistronic promoterless construct: production of an ADA-deficient homozygote ES cell line.

In man, deficiency of ADA activity is associated with an autosomal recessive form of severe combined immunodeficiency (SCID), a disease with profound defects both cellular and humoral immunity. Current treatments of ADA deficient patients include bone marrow transplantation, enzyme replacement and somatic gene therapy. The mechanism of the selective immune cell pathogenesis in ADA-SCIDS is, however, still poorly understood. Thus, the generation of an ADA deficient mouse model will be of considerable benefit to understand better the pathophysiology of the disorder and to improve the gene therapy treatments. We have disrupted the adenosine deaminase (ADA) gene in embryonic stem cells using a new efficient promoter trap gene-targeting approach. To this end, a dicistronic targeting construct containing a promoterless IRES beta geo cassette was used. This cassette allows, via the internal ribosomal entry site (IRES), the direct cap-independent translation of the beta geo reporter gene which encodes a protein with both beta-galactosidase and neomycin activities. After indentification of targeted clones by Southern blot, successful inactivation of the ADA gene was first confirmed by producing, from our heterozygote clones, an homozygote cell line. This line shows no ADA activity as judged by zymogram analysis. Second, we have been able to detect in the targeted clones, a specific beta galactosidase activity using a sensitive fluorogenic assay. The targeted ES cell clones are currently being injected into blastocysts to create an ADA deficient mouse model.