Publications by authors named "John J Carney"

8 Publications

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Treatment of tibial plateau fractures with a novel fenestrated screw system for delivery of bone graft substitute.

Eur J Orthop Surg Traumatol 2021 Jan 24. Epub 2021 Jan 24.

Department of Orthopaedic Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA.

Purpose: The purpose of this study was to describe the incidence of subsidence in patients with AO/OTA 41 (tibial plateau) fractures which were repaired with a novel fenestrated screw system to used to deliver CaPO4 bone substitute material to fill the subchondral void and support the articular reduction.

Methods: Patients with unicondylar and bicondylar tibial plateau fractures were treated according to the usual technique of two surgeons. After fixation, the Zimmer Biomet N-Force Fixation System®, a fenestrated screw that allows for the injection of bone substitute was placed and used for injection of the proprietary calcium phosphate bone graft substitute into the subchondral void. For all included patients, demographic information, operative data, radiographs, and clinic notes were reviewed. Patients were considered to have articular subsidence if one or more of two observations were made when comparing post-operative to their most recent clinic radiographs: > 2 mm change in the distance between the screw and the lowest point of the tibial plateau, > 2 mm change in the distance between the screw and the most superior aspect of the plate. Data were analyzed to determine if there were any identifiable risk factors for complication, reoperation, or subsidence using logistic regression. Statistical significance was set at p < 0.05.

Results: 34 patients were included with an average follow-up of 32.03 ± 22.52 weeks. There were no overall differences between height relative to the medial plateau or the plate. Two patients (5.9%) had articular subsidence. Six patients (15.2%) underwent reoperation, two (6%) for manipulations under anaesthesia due to arthrofibrosis, and four (12%) due to infections. There were 6 (19%) total infections as 2 were superficial and required solely antibiotics. One patient had early failure.

Conclusion: Use of a novel fenestrated screw system for the delivery of CaPO4 BSM results in articular subsidence and complication rates similar to previously published values and appears to be a viable option for addressing subchondral defects in tibial plateau fractures.

Level Of Evidence: IV.
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http://dx.doi.org/10.1007/s00590-021-02871-yDOI Listing
January 2021

Ballistic trauma patients have decreased early narcotic demand relative to blunt trauma patients: Blunt ballistic injury opioid use.

Injury 2021 May 15;52(5):1234-1238. Epub 2020 Sep 15.

Department of Orthopaedic Surgery, Cedars-Sinai Medical Center, Los Angeles, CA, United States. Electronic address:

Objectives: Blunt and ballistic injuries are two common injury mechanisms encountered by orthopaedic traumatologists. However the intrinsic nature of these injures may necessitate differences in operative and post-operative care. Given the evolving opioid crisis in the medical community, considerable attention has been given to appropriate management of pain; particularly in orthopaedic patients. We sought to evaluate relative postoperative narcotic use in blunt injuries and ballistic injuries.

Design: Retrospective Cohort Study.

Setting: Academic Level-1 Trauma Center.

Patients: 96 Patients with blunt or ballistic fractures.

Intervention: Inpatient narcotic pain management after orthopaedic fracture management.

Main Outcome Measurements: Morphine equivalent units (MEU).

Results: Patients with blunt injuries had a higher MEU compared to ballistic injuries in the first 24 hours postoperatively (35.0 vs 29.5 MEU, p=0.02). There were no differences in opiate consumption 24-48 hours (34.8 vs 28.0 MEU), 48 hours - 7 days post op (28.4 vs 30.4 MEU) or the 24 hours before discharge (30.0 vs 28.6 MEU). On multivariate analysis, during the 24-48 hours and 24 hours before discharge timepoints total EBL was associated with increased opioid usage. During days 3-7 (p<0.001) and in the final 24 hours prior to discharge (p=0.012), the number of orthopaedic procedures was a predictor of opioid consumption.

Conclusion: Blunt injuries required an increased postoperative narcotic consumption during the first 24 hours of inpatient stay following orthopedic fracture fixation. However, there was no difference at other time points. Immediate post-operative pain regimens may be decreased for patients with ballistic injuries.

Level Of Evidence: III.
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http://dx.doi.org/10.1016/j.injury.2020.09.005DOI Listing
May 2021

A Survey to Assess Agreement Between Pelvic Surgeons on the Outcome of Examination Under Anesthesia for Lateral Compression Pelvic Fractures.

J Orthop Trauma 2020 09;34(9):e304-e308

Department of Orthopaedics, University of Southern California, Los Angeles, CA.

Objectives: To assess agreement among pelvic surgeons regarding the interpretation of examination under anesthesia (EUA), the methodology by which EUA should be performed, and the definition of a positive examination.

Design: Survey.

Patients/participants: Ten patients who presented to our Level 1 trauma center with a pelvic ring injury were selected as clinical vignettes. Vignettes were distributed to 15 experienced pelvic surgeons.

Intervention: Examination under anesthesia.

Main Outcome Measurements: Agreement regarding pelvic fracture stability (defined as >80% similar responses), need for surgical fixation, definition of an unstable EUA, and method of performing EUA.

Results: There was agreement that a pelvic fracture was stable or unstable in 8 (80%) of 10 cases. There was agreement that fixation was required or not required in 6 (60.0%) of 10 cases. Seven (46.7%) surgeons endorsed performing a full 15-part EUA, whereas the other 8 (53.3%) used an abbreviated or alternative method. Eight (53.3%) surgeons provided a definition of what constitutes a positive EUA, whereas the remaining 7 did not endorse adhering to a strict definition.

Conclusions: Pelvic surgeons generally agree on what constitutes a positive or negative EUA but not necessarily the implications of a positive or negative examination. There is no clear consensus among surgeons regarding the method of performing EUA nor regarding the definition of a positive EUA.

Level Of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.
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http://dx.doi.org/10.1097/BOT.0000000000001759DOI Listing
September 2020

Effect of bariatric surgery on outcomes in the operative treatment of hip fractures.

Injury 2020 Mar 21;51(3):688-693. Epub 2020 Jan 21.

Department of Orthopaedic Surgery, Keck School of Medicine of the University of Southern California, 1200N. State St. GNH 3900, Los Angeles, CA 90033, United States.

Introduction: Few studies have evaluated the effect of prior bariatric surgery on outcomes following the operative treatment of hip fractures. The purpose of this study is to evaluate these metrics in a population of bariatric surgery patients compared to a control group who were operatively treated for hip fractures.

Materials And Methods: The California Office of Statewide Health Planning & Development (OSHPD) discharge database was accessed to identify patients who sustained a hip fracture between 2000-2014. CPT codes were utilized to identify patients who had a prior history of bariatric surgery within this time period. A control cohort of patients who had undergone previous appendectomy were queried similarly. The study evaluated complication rates and inpatient mortality at 30- and 90-days postoperatively as well as 30- and 90-day readmission rates.

Results: There were 1,327 bariatric and 2,127 control patients identified. Survival rates were significantly lower in bariatric patients compared to controls (87.2% vs. 91.8%, p = 0.048) at 5 years. After controlling for confounders, bariatric patients had higher 30- (OR 1.46, p = 0.005) and 90-day (OR 1.38, p = 0.011) readmission rates. There were no differences in all-cause complication and inpatient mortality rates between groups at 30 or 90 days.

Discussion: Bariatric surgery patients are at increased risk of readmission after hip fracture surgery. Further research is warranted to delineate potential risk factors and mitigate readmission in these patients.

Level Of Evidence: III.
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http://dx.doi.org/10.1016/j.injury.2020.01.022DOI Listing
March 2020

Characteristics of Marijuana Use Among Orthopedic Patients.

Orthopedics 2020 Mar 16;43(2):108-112. Epub 2019 Dec 16.

Marijuana use among orthopedic patients has not been extensively studied. The purpose of this study was to investigate the prevalence of marijuana use among orthopedic surgery patients. Additionally, the authors sought to better characterize how and why their patients use marijuana. Patients presenting at 3 institutions in 2 states for orthopedic surgery were asked to complete a voluntary survey. In addition to basic demographic information, the survey contained questions regarding the frequency of, methods of, and reasons for marijuana use. Patients who had used marijuana in the past year were categorized as marijuana users. A total of 275 patients completed surveys, of whom 94 (34%) endorsed marijuana use in the past year. A majority of marijuana users (55%) endorsed using marijuana either daily or weekly. Smoking was the most common means of marijuana use (90%), followed by edible products (35%) and vaporizing (24%). Pain management (54%) and recreation (52%) were the most commonly cited reasons for using marijuana. Eighty-six percent of marijuana users indicated that they would stop using marijuana if told by their physician that marijuana use would adversely affect their surgery. Marijuana use is common among orthopedic patients. Many patients believe marijuana is beneficial for managing pain and other medical conditions, although most would be willing to stop using marijuana if told it would negatively impact their surgery. Further study into the effects of marijuana use on musculoskeletal health is warranted because marijuana use may be a risk factor easily modified to improve surgical outcomes. [Orthopedics. 2020; 43(2): 108-112.].
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http://dx.doi.org/10.3928/01477447-20191212-07DOI Listing
March 2020

Exploratory Study of Heart Rate Variability and Sleep among Emergency Medical Services Shift Workers.

Prehosp Emerg Care 2017 Jan-Feb;21(1):18-23. Epub 2016 Aug 3.

Objectives: To characterize the continuity and duration of sleep, and to measure nocturnal cardiac autonomic balance via heart rate variability (HRV) in a group of emergency medical technicians (EMTs) on and off duty.

Methods: Fourteen EMTs completed an online, daily sleep log that recorded total sleep duration, bedtime, rise time, and the number of alarms that caused awakening. HRV was captured using a physiological status monitor (PSM) affixed to a chest strap during sleep.

Results: For the 7-day trial, each of the 14 EMTs logged three work days (WDs) and four non-work days (NWDs). They reported sleeping significantly fewer hours per night on WDs (6.4 ± 2.1) than on NWDs (7.9 ± 0.5; P < 0.05), and experienced more sleep disruptions on WDs (4.4 ± 2.8) than on NWDs (1.3 ± 2.2; P < 0.001) as measured by the number of alarms. Global and vagal indices of HRV during sleep were significantly reduced during WDs (Standard Deviation of Normal R-R Intervals (SDNN) = 43.4 ± 2.0 ms and High Frequency (HF) = 24.3 ± 1.2 ms) when compared to NWDs (SDNN = 61.1 ± 1.0 ms and HF = 42.7 ± 1.5 ms; P < 0.001).

Conclusion: EMTs who worked 24-hour shifts had shorter, more fragmented sleep associated with greater cumulative exposure to increased sympathetic and decreased parasympathetic activity as measured via sleep HRV. These changes in cardiac autonomic tone constitute one plausible pathway through which sleep deprivation may increase risk for cardiovascular disease.
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http://dx.doi.org/10.1080/10903127.2016.1194928DOI Listing
June 2017

Scalable modulator for frequency shift keying in free space optical communications.

Opt Express 2013 Feb;21(3):3342-53

MIT Lincoln Laboratory, 244 Wood St., Lexington, Massachusetts 02420, USA.

Frequency shift keyed (FSK) modulation formats are well-suited to deep space links and other high loss links. FSK's advantage comes from its use of bandwidth expansion. I.e., FSK counteracts power losses in the link by using an optical bandwidth that is greater than the data rate, just as pulse position modulation (PPM) does. Unlike PPM, increasing FSK's bandwidth expansion does not require increased bandwidth in electronic components. We present an FSK modulator whose component count rises logarithmically with the bandwidth expansion. We tested it with four-fold bandwidth expansion at 5 and 20 Gbit/s. When paired with a pre-amplified receiver, the required received power was about 4 and 5 dB from the theoretical best for such receivers. We also tested the FSK transmitter with a photon counting receiver.
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http://dx.doi.org/10.1364/OE.21.003342DOI Listing
February 2013

781 Mbit/s photon-counting optical communications using a superconducting nanowire detector.

Opt Lett 2006 Feb;31(4):444-6

MIT Lincoln Laboratory, Lexington, Massachusetts 02420, USA.

We demonstrate 1550 nm photon-counting optical communications with a NbN-nanowire superconducting single-photon detector. Source data are encoded with a rate-1/2 forward-error correcting code and transmitted by use of 32-ary pulse-position modulation at 5 and 10 GHz slot rates. Error-free performance is obtained with -0.5 detected photon per source bit at a source data rate of 781 Mbits/s. To the best of our knowledge, this is the highest reported data rate for a photon-counting receiver.
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http://dx.doi.org/10.1364/ol.31.000444DOI Listing
February 2006