[West J Emerg Med. 2014;15(1):7–8.]

BACKGROUND: Aseptic complications such as stress shielding leading to bone loss are major problems associated with revision of cemented and uncemented long-stem tumor endoprostheses. Endoprosthetic reconstruction using compressive osseointegration fixation is a relatively new limb salvage technology designed to enhance osseointegration, prevent stress shielding, and provide fixation for short end-segments. QUESTIONS/PURPOSES: (1) What is the survivorship of this technique at minimum 5-year followup? (2) Were patient factors (age, sex, body mass index), oncological factors, or anatomic locations associated with implant failure? (3) Were there any prosthesis-related variables associated with failure? METHODS: A single-center, retrospective review of patients with a minimum 5-year followup (mean, 8 years; range, 5-12 years) treated with an osseointegration compressive device for endoprosthetic fixation of proximal and distal femoral limb salvage reconstructions was performed. We have previously published the implant survivorship of this patient cohort with a minimum 2-year followup and are now reporting on the 5-year survivorship data. From 2002 to 2008, we performed 22 such procedures in 22 patients. Four patients died of their disease within 5 years of surgery and all surviving patients (n = 18) had complete followup data at a minimum of 5 years. General indications for this device during that time were pediatric and adult patients requiring primary endoprosthetic reconstructions of the proximal or distal femur for benign and malignant bone lesions. The primary outcome was reoperations for mechanical (aseptic) failures. Secondary outcomes included implant removal for nonmechanical failures and any patient-, oncological-, or implant-related variables associated with implant removal. RESULTS: At a minimum of 5 years followup, overall mechanical (aseptic) implant survivorship was 16 of 18. Survivorship for all modes of failure (oncological failure, infection, arthrofibrosis, and mechanical failure) was 12 of 18. All mechanical failures occurred early, within the first 30 months. We identified no patient-, oncological-, or implant-related features predictive of failure. CONCLUSIONS: Our intermediate-term experience with compressive osseointegration fixation for endoprosthetic limb reconstructions demonstrates with longer clinical followup, no additional mechanical failures were observed as compared with our early analysis. Our experience with this fixation at a minimum of 5-years followup adds to a very limited but increasing body of literature demonstrating that after a transient period of increased risk for implant failures, survivorship stabilizes. Assessment of this fixation strategy beyond 10 years of clinical followup is needed. LEVEL OF EVIDENCE: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Rotationplasty is an alternative reconstructive strategy after sarcoma resection that often gets overlooked due to concerns about cosmesis. Rotating a distal segment 180 degrees and fixing it to a proximal segment leaves a highly-functional, durable reconstruction that functionally compares favorably to other limb-salvage techniques. Cosmetic outcomes have no discernible impact of the emotional and social functioning of cancer survivors following rotationplasty. This chapter discusses techniques of rotationplasty, as well as its oncologic, functional and emotional outcomes.

Dizocilpine maleate (MK-801) is one of several NMDA receptor antagonists that is widely used to pharmacologically model the symptoms of psychosis and schizophrenia in animals. MK-801 elicits behaviors in adult zebrafish (Danio rerio) that are phenotypically consistent with behaviors observed in humans and rodents exposed to the drug. However, the molecular and cellular processes that mediate the psychotomimetic, cognitive and locomotive behaviors of MK-801 are unclear. We exposed zebrafish larvae to MK-801 to assess their merit as a model organism to elucidate the behavioral effects of NMDA receptor blockade. Zebrafish larvae were acutely immersed in MK-801 to assess the effect on spontaneous swimming. MK-801 caused a time- and dose-dependent increase in larval swim speed, and the peak response (a five-fold increase in swim speed) was evoked by a three h exposure to a 20 uM dose. Zebrafish larvae did not exhibit sensitivity to the locomotor effectsof MK-801 until 5 dpf, suggesting a critical role for developmental in sensitivity to the drug. Exposure to the low potency NMDA antagonist, memantine, did not alter the swim speed of zebrafish larvae. Co-immersion in D 1 or D2 dopamine receptor antagonists did not disrupt the time course or magnitude of the increase in swim speed, suggesting dopaminergic signaling is not required for the locomotor actions of MK-801. Our findings of the behavioral actions of MK-801 in zebrafish larvae are consistent with previous observations in mammals and imply that the physiological, cellular and molecular processes disrupted by MK-801 are conserved in zebrafish larvae. These data suggest that the zebrafish larvae is a valid and useful model to elucidate neurobehavioral aspects of NMDA receptor antagonism and may provide insight to the neurobiology of psychosis and schizophrenia.

The use of noninvasive transcranial electrical stimulation (tES) has rapidly increased over the past two decades. Yet, tES continues to be largely implemented in laboratory and rehabilitation settings, thereby limiting accessibility to the broader population. We have previously demonstrated that transcranial alternating current stimulation (tACS) in the theta (4-7 Hz) band improves cognitive control, such as multitasking, in younger adults following a single tACS session, as well as in older adults following three tACS sessions. Here, the goal was to extend our in-lab results by (1) assessing the feasibility for at-home tACS and (2) evaluating whether five tACS sessions may yield continuing improvements in multitasking ability in young adults. Participants (aged 18 - 34 years) received bilateral prefrontal tACS while engaged in an adaptive multitasking training over five consecutive days in their home settings. Participants were randomly assigned to receive either 20-minutes of theta or delta tACS during daily multitasking training. Prior to and on the day immediately following five days of tACS, we assessed performance on single task, multitask, and sustained attention ability with analyses of variance statistics. 92.1% of participants were able to self-administer tACS at home without researcher assistance. However, we observed that both theta and delta tACS groups exhibited improvements in both single and multitask performance. Compared to previously collected data, five days of theta tACS was comparable to one day of theta tACS. However, theta tACS has continued benefits in older, but not younger adults as evidenced by previous research. Both groups similarly improved in sustained attention. These results demonstrate that laboratory paradigms utilizing neurostimulation can be effectively deployed in a home environment without direct support from research personnel. Moreover, these results suggest that while theta tACS may facilitate multitasking improvements over one session, multiple sessions of theta tACS results in diminishing returns in young adults. Additional research will be required to confirm if delta activity plays an important role in multitasking ability.

Soft tissue sarcomas are a rare group of mesenchymal malignancies which can range from low to high grade. These tumors have different clinical, radiographic, and histopathological characteristics. Beta human chorionic gonadotropin is a naturally secreted hormone by placental syncytiotrophoblast cells during pregnancy. On very rare occasions, sarcomas can develop the ability to ectopically produce human chorionic gonadotropin. Very few cases exist in the literature of soft tissue sarcomas expressing this hormone. We report the case of a 55-year-old female who presented with a posterior thigh soft tissue sarcoma who on the day of surgical resection was found to have an unusually elevated serum human chorionic gonadotropin. Positive immunohistochemical staining of the resected mass confirmed the sarcoma as the source of the beta human chorionic gonadotropin.