Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Late posterior hip instability after lumbar spinopelvic fusion

The kinematic relationship between the hip and the axial skeleton is dynamic and can be variable based on individual anatomy. It has been shown [1] that pelvic incidence (sacral slope + pelvic tilt) can be used as a proxy to determine the ability of the pelvis to accommodate changes in sagittal balance. Individuals have varied pelvic incidence and thus may adapt differently degenerative and/or iatrrogenic to changes that occur in the axial spine. This is a case report in which surgical changes to the lumbopelvic spine resulted in chronic posterior periprosthetic hip instability. The focus of this discussion reflects the intimate relationship between the hip and spine and highlights the role between sagittal balance and acetabular version, specifically as it pertains to total hip arthroplasty

Early femoral condyle insufficiency fractures after total knee arthroplasty: treatment with delayed surgery and femoral component revision

Background: Periprosthetic fracture following total knee arthroplasty (TKA) is usually associated with a traumatic event and typically treated with fracture fixation techniques. However, we report on a series of patients with early atraumatic condyle fractures that occurred as a result of insufficiency of the unloaded preoperative femoral condyle treated with delayed reconstruction. Methods: We retrospectively reviewed a series of 7 patients who sustained femoral condyle fractures following TKA and evaluated risk factors for insufficiency. Results: There were 6 females and 1 male with an average age of 65.5 (range, 63-75) years and an average body mass index of 29.4 (range, 27-32). Fracture occurred on average 24.9 days from the index surgery and secondary to a low energy mechanism. Five patients had valgus alignment (mean, 15.2°) preoperatively and sustained fracture of the unloaded medial femoral condyle. Two patients had varus alignment (mean, 7.0°) preoperatively and both fractured the unloaded lateral condyle. One patient underwent early intervention requiring distal femoral replacement secondary to femoral bone loss. The remaining 6 patients underwent delayed surgery for an average of 6 weeks to allow for fracture healing followed by femoral component revision. At last follow-up (average, 48.5 months), 1 patient required a tibial component revision; however, no revision of the femoral component was required. Conclusions: Early femoral condyle insufficiency fractures following TKA may be a risk in females with poor bone quality and preoperative valgus alignment. Delayed surgery and femoral component revision is a treatment strategy that prevented the need for other tertiary reconstruction

Highlights of the 2022 American Joint Replacement Registry Annual Report

The 2022 American Joint Replacement Registry Annual Report includes data from over 2.8 million hip and knee procedures from over 1,250 institutions that encompass all 50 states and the District of Columbia. This represents a cumulative registered procedural volume growth of 14% compared to the previous year, making the American Joint Replacement Registry the largest arthroplasty registry by volume in the world

Are reinfusion drains safe to use with periarticular liposomal bupivacaine? An analysis of systemic bupivacaine toxicity

Background: Intraoperative periarticular injection (PAI) with local anesthetic is an important component of multimodal pain control in total joint arthroplasty (TJA). A potential risk of this practice is serum anesthetic toxicity resulting from the autotransfusion of blood collected from a reinfusion drain. The purpose of this study is to evaluate the levels of bupivacaine in blood collected in an autotransfusion system after use of a PAI in TJA. Methods: In this prospective study, each TJA patient had an identical PAI consisting of 20 cc of liposomal bupivacaine, 30 cc of 0.25% bupivacaine with epinephrine, and 10 cc of normal saline. An autologous reinfusion drain was utilized in all patients. At 2 and 5 hours postoperatively, blood was collected from the autotransfusion canister and sent to the laboratory to quantify bupivacaine levels. The sums of these levels were compared to the lowest reported serum bupivacaine dose associated with toxicity (1.1 mg/kg). Results: Eleven unilateral TJA patients were enrolled (6 total knee arthroplasties, 5 total hip arthroplasties). The average 2-hour serum bupivacaine level was 2.9 μg (range 0.8-5.6) while the average 5-hour serum bupivacaine level was 4.5 μg (range 0.4-10.0). The average sum of the 2-hour and 5-hour serum bupivacaine level was 5.6 μg (range 0.8-13.6). Each of the 11 patient samples were well below their minimum serum bupivacaine dose toxicity. Conclusions: Use of a reinfusion drain after PAI with liposomal bupivacaine in TJA appears safe, as bupivacaine levels in the autotransfused blood remains well below the reported minimum serum toxic dose. Level of Evidence: IV

Infection burden in total hip and knee arthroplasties: an international registry-based perspective

Background: Infection remains a leading cause of failure of hip and knee replacements. Infection burden is the ratio of implants revised for infection to the total number of arthroplasties in a specific period, measuring the steady state of infection in a registry. We hypothesized infection burden would be similar among arthroplasty registries. Methods: We evaluated publicly reported data from 6 arthroplasty registries (Australian Orthopaedic Association National Joint Replacement Registry [AOANJRR], New Zealand Joint Registry, Swedish Hip Arthroplasty Register, Swedish Knee Arthroplasty Register, National Joint Registry of England, Wales, Northern Ireland, and the Isle of Man, and the American Joint Replacement Registry) for revisions performed with an infection diagnosis over the last 6 years. Results: The 2015 hip infection burden varied between registries from 0.76% (AOANJRR) to 1.24% (Swedish Hip Arthroplasty Register), and the unweighted overall average for hip infection burden was 0.97%. In 2012, 2013, and 2014, average hip infection burden held steady at 0.87%, 0.93%, and 0.94%, respectively, higher than the preceding 2 years. The 2015 knee infection burden varied from 0.88% (AOANJRR) to 1.28% (Swedish Knee Arthroplasty Register), and the unweighted average was 1.03%. In 2012, 2013, and 2014, knee infection burden was 1.04%, 1.11%, and 1.02%, respectively. These numbers were also higher than the preceding 2 years. Conclusions: Infection burden may be one measure of the overall success in registry populations as well as monitoring the steady state of infection worldwide. Despite global efforts to reduce postoperative infection, infection burden has actually increased in the selected registries over time