Atraumatic Fracture of the Femoral Component of a Cemented Total Knee Arthroplasty: A Case Report.

CASE: An 81-year-old man presented with severe atraumatic knee pain. Sixteen years before, he had undergone a primary cemented total knee arthroplasty (TKA). A radiological study showed osteolysis and loosening of the femoral component. Intraoperatively, a medial femoral condyle fracture was found. A rotating-hinge revision TKA with cemented stems was implanted. CONCLUSION: Femoral component fracture is extremely rare. Surgeons should remain vigilant with younger and heavier patients with severe unexplained pain. Early revision TKA using cemented, stemmed, and more constrained implants is usually necessary. Full and stable metal-to-bone contact through perfect cuts and a careful cementing technique avoiding debonded areas are recommended to prevent this complication.

High reoperation and mortality rate after distal femoral replacement for periprosthetic knee fracture in the elderly.

PURPOSE: To analyze the outcomes of elderly patients with periprosthetic fractures around the knee operated on with a distal femur replacement (DFR). METHODS: We performed a retrospective case series study of eleven elderly patients who underwent DFR due to a periprosthetic fracture. Mean follow-up was 30.1 months (SD 28.1). Demographic, clinical and radiological data were reviewed. A descriptive analysis and a study of survival were conducted. Then, a comparative analysis between the patients who needed reoperation and did not need reoperation, and the patients who died and the patients who were alive during the follow-up was performed. RESULTS: Mean age was 77.1 years (SD 13.9). Reoperation rate was 36%, being infection the most common complication (27%). The risk of reoperation increased with a longer time between fracture and surgery. The 36.4% of patients died during the follow-up. Older age, need of blood transfusion and need of early reoperation were related to a higher risk of mortality. CONCLUSION: DFR could be a valuable option for knee periprosthetic fractures in elderly patients. However, surgeons should be aware of the high reoperation and mortality rate.

Preoperative mechanical axis has no influence on reoperation rate in primary rotating-hinge knee arthroplasty.

Background: The purpose of the study is to evaluate reoperation rate and its relationship to preoperative mechanical axis of rotating-hinge TKA used as the primary implant in complex knees. Methods: Patients subjected to primary TKA with a rotating-hinge knee prosthesis due to primary osteoarthritis between 2010 and 2019 were retrospectively reviewed. Preoperative mechanical axis was measured using the last preoperative telemetry x-ray image. Preoperative axis was classified according to the type of deformity (varus or valgus) and its magnitude (0-15°, 16-25° or >25°). Reoperation rate (with or without implant removal) was the primary outcome of the current study. We studied if the preoperative mechanical axis (either varus-valgus, or magnitude of malalignment) was related to implant survival rate. Results: Forty-two patients were included in the study. Mean follow-up was 51.42 ± 31.88 months. The 83.3% of patients presented a valgus axis while the 16.7% presented a varus axis. Need of reoperation occurred in eight patients (19.0%). However, no patients (0%) required implant removal with revision TKA. No association was seen between the preoperative mechanical axis and risk of reoperation (p = 0.16). Conclusion: In selected situations that do not permit less constrained implants, primary rotating-hinge arthroplasty could be a good alternative. Risk of reoperation does not seem to depend upon the preoperative mechanical axis when using a rotating-hinge knee prosthesis for primary arthroplasty in non-tumoral complex knees.

Analysis of the Ordinary and Extraordinary Ionospheric Modes for NVIS Digital Communications Channels.

Sensor networks have become more popular in recent years, now featuring plenty of options and capabilities. Notwithstanding this, remote locations present many difficulties for their study and monitoring. High-frequency (HF) communications are presented as an alternative to satellite communications, being a low-cost and easy-to-deploy solution. Near vertical incidence skywave (NVIS) technology provides a coverage of approximately 250 km (depending on the frequency being used and the ionospheric conditions) without a line of sight using the ionosphere as a communication channel. This paper centers on the study of the ionosphere and its characteristic waves as two independent channels in order to improve any NVIS link, increasing its robustness or decreasing the size of the node antennas through the appliance of specific techniques. We studied the channel sounding of both the ordinary and extraordinary waves and their respective channels, analyzing parameters such as the delay spread and the channel's availability for each wave. The frequency instability of the hardware used was also measured. Furthermore, the correlation coefficient of the impulse response between both signals was studied. Finally, we applied polarization diversity and two different combining techniques. These measurements were performed on a single frequency link, tuned to 5.4 MHz. An improvement on the mean bit energy-to-noise power spectral density (Eb/N0) was received and the bit error rate (BER) was achieved. The results obtained showed that the extraordinary mode had a higher availability throughout the day (15% more availability), but a delayed spread (approximately 0.3 ms mean value), similar to those of the ordinary wave. Furthermore, an improvement of up to 4 dB was achieved with the usage of polarization diversity, thus reducing transmission errors.

NVIS Multicarrier Modulations for Remote-Sensor Applications.

The number of Internet of Things (IoT) devices has experienced a large growth during the last decade, as well as the data volume gathered from remote sensors. Satellites are still a suitable communication method and may be preferable for a remote ubiquitous sensor network (USN), which sometimes are located in places without much communications infrastructure where coverage is the principal drawback. Alternatively, the proposed solution for this article aims at a near-vertical incidence skywave (NVIS) channel for high frequencies (HF) with a low-cost platform, allowing a low-power transmissions coverage area up to 250 km for USN. The HF standards are focused on generic communication channels not being robust for NVIS communications. In this article we study and test an alternative based on orthogonal frequency-division multiplexing (OFDM) modulations to make them more robust and less dependent on the channel NVIS communications. For that purpose, we test the HF standard modulations and a designed OFDM modulation to prove the robustness of each. This study has been tested between Barcelona and Tarragona, using different transmission power levels and modulation orders.

Rethinking Trauma Hospital Services in one of Spain's Largest University Hospitals during the COVID-19 pandemic. How can we organize and help? Our experience.

INTRODUCTION: The severe disruptions caused by the SARS-CoV-2 coronavirus have necessitated a redistribution of resources to meet hospitals' current service needs during this pandemic. The aim is to share our experiences and outcomes during the first month of the Covid-19 pandemic, based on the strategies recommended and strategies we have implemented. METHODS: Our experience comes from our work at a referral hospital within the Spanish National Health System. Changes to clinical practice have largely been guided by the current evidence and four main principles: (1) patient and health-care worker protection, (2) uninterrupted necessary care, (3) conservation of health-care resources, (4) uninterrupted formation for residents. Based on these principles, changes in the service organization, elective clinical visits, emergency visits, surgical procedures, and inpatient and outpatient care were made. RESULTS: Using the guidance of experts, we were able to help the hospital address the demands of the Covid-19 outbreak. We reduced to a third of our orthopaedics and trauma hospital beds, provided coverage for general emergency services, and five ICUs, all continuing to provide care for our patients, in the form of 102 trauma surgeries, 6413 phone interviews and 520 emergency clinic visits. Also in the third week, we were able to restart morning meetings via telematics, and teaching sessions for our residents. On the other hand, eight of the healthcare personnel on our service (10.8%) became infected with Covid-19. CONCLUSIONS: As priorities and resources increasingly shift towards the COVID-19 pandemic, it is possible to maintain the high standard and quality of care necessary for trauma and orthopaedics patients while the pandemic persists. We must be prepared to organize our healthcare workers in such a way that the needs of both inpatients and outpatients are met. It is still possible to operate on those patients who need it. Unfortunately, some healthcare workers will become infected. It is essential that we protect those most susceptible to severer consequences of Covid-19. Also crucial are optimized protective measures.

Nosocomial infection with SARS-CoV-2 and main outcomes after surgery within an orthopaedic surgery department in a tertiary trauma centre in Spain.

AIMS: The purpose of the present study is to analyse clinical data of a series of cases who developed nosocomial infection with SARS-CoV-2 in an orthopaedic and traumatology department. PATIENTS AND METHODS: In this non-interventional retrospective study, carried out at a tertiary hospital within the Spanish National Health System, all adult patients who were admitted in the Orthopaedic Surgery and Traumatology Department between March 9th and May 4th, 2020, were included. Clinical, biological and radiological data, as well as mortality rates, were collected from hospital medical records. RESULTS: A total of 293 periods of hospitalization were analysed in 288 patients. Mean age was 66.1 years old and 57.3% were females. Nineteen patients (6.48%) met the inclusion criteria to be categorized as a nosocomial infection with SARS-CoV-2. In a comparison between patients with and without nosocomial infection, age, mortality and hospital length of stay were statistically significant (p < 0.05). The median time from admission to diagnosis of SARS-CoV-2 infection in our cohort was 16 days (6-86 days). No statistically significant differences were found in sex, living situation, reason of admission or period of admission (even if we observed that most of the nosocomial infections (78.9%) occurred in March). CONCLUSION: We have found a 6.48% of nosocomial infection with SARS-CoV-2, but with an important reduction of it after undergoing preventing protocols that included screening RT-PCR test for COVID-19. Age and hospital length stay were statistically significant risk factors for nosocomial infection with SARS-CoV-2. For the progressive restoration of the surgical activity, we recommend to correctly select the patients in elective surgery and to encourage fast-track programs and early discharge of patients with fractures.