Long-Term Implant Survivorship and Modes of Failure in Simultaneous Concurrent Bilateral Total Knee Arthroplasty.

BACKGROUND: There is limited evidence describing long-term implant survivorship and modes of failure in simultaneous concurrent bilateral total knee arthroplasty (TKA). METHODS: We performed a retrospective review of 266 consecutive patients (532 knees) who underwent simultaneous concurrent bilateral TKA. We reviewed medical records for preoperative characteristics, perioperative complications, and revision surgeries. The primary outcome was TKA survivorship. Secondary outcomes included indication and type of revision surgery. We used the Kaplan-Meier method to estimate survivorship and characterize risk of revision up to 20 years post-TKA. RESULTS: Our cohort had median follow-up of 9.8 years (interquartile range, 3.9-15.9). Forty-four patients (17%) underwent revision. Revision was more common among younger and male patients. The cumulative incidence of first-time revision per knee (n = 532) was 1.27 per 100 component-years. Implant survival was 99% (confidence interval, 97%-99%) at 5 years, 92% (89%-95%) at 10 years, 83% (77%-87%) at 15 years, and 62% (50%-73%) at 20 years. Five and 10-year survivorship compared favorably to estimates of TKA survivorship in the literature. The cumulative incidence of revision surgery per patient was 1.91 per 100 component-years. Implant survival at 5-, 10-, 15-, and 20-year time points was 96% (CI, 92%-98%), 84% (77%-89%), 71% (62%-79%), and 59% (46%-70%), respectively. Aseptic loosening (40%), polyethylene wear (34%), and infection (11%) were the most common indications for revision. CONCLUSION: Simultaneous concurrent bilateral TKA is associated with a higher risk of reoperation for the patient when both knees are evaluated but similar implant survivorship to the literature when each knee was evaluated in isolation.

Effectiveness of local anesthetic injection in geriatric patients following operative management of proximal and diaphyseal femur fracture.

INTRODUCTION: Geriatric fracture patients are at risk for poorly controlled pain and side effects of opioid medications. The arthroplasty literature has demonstrated that infiltration of long-acting local anesthetic or anesthetic cocktails improves pain control and reduces post-operative opioid use resulting in better postoperative mobility without the deleterious effects of narcotics. Despite having a higher risk for adverse events, there is limited data among geriatric trauma patients. The aim this study was to evaluate whether local anesthetic infiltration (LAI) into the soft tissues surrounding the surgical field reduces narcotic use or pain scores in patients undergoing surgical management of proximal and diaphyseal femur fractures. MATERIALS AND METHODS: A retrospective review was performed of patients age >65 undergoing operative intervention for proximal and diaphyseal femur fracture. The electronic record was utilized to determine if local anesthetic was injected into the surgical wound, the amount of narcotics administered over 48 h in four-hour intervals, and to obtain visual analog scale (VAS) pain scores associated with patients post-operative course in four-hour intervals. The amount of narcotics was converted to morphine milligram equivalents (MME). RESULTS: Among 477 patients with femur fracture, 358 did not receive LAI and 119 patients received LAI. Baseline demographics, fracture types, and surgical procedure were equivalent between the groups. In the first 28 h following surgery, compared with those who did not receive LAI, those who did required significantly less opioid (57.8 MME versus 94.3 MME, p = 0.034) and despite decreased narcotics, had equal pain scores (mean difference 0.37, p = 0.22). There was no difference in rates of post-operative complications. CONCLUSION: LAI is associated with a reduction in opioid consumption in geriatric fracture patients with equivalent pain scores. Optimizing pain control is a critical issue in caring for geriatric fracture patients since both under-treated pain and opioid medications are implicated in postoperative delirium, complications, and ability to mobilize early. More research is needed to identify effective ways to optimize pain management in this at-risk patient population.

Is magnetic resonance imaging in addition to a computed tomographic scan necessary to identify clinically significant cervical spine injuries in obtunded blunt trauma patients?

BACKGROUND: Guidelines are in place directing the clearance of the cervical spine in patients who are awake, alert, and oriented, but a gold standard has not been recognized for patients who are obtunded. Our study is designed to determine if magnetic resonance imaging (MRI) detects clinically significant injuries not seen on computed tomographic (CT) scans. METHODS: The trauma registry was used to identify and retrospectively review medical records of blunt trauma patients from January 1, 2005, to March 30, 2012. Only obtunded patients with a CT scan and MRI of the cervical spine were included. RESULTS: The study cohort consisted of 277 patients. In 13 (5%) patients, MRI detected clinically significant cervical spine injuries that were missed by CT scans, and in 7 (3%) these injuries required intervention. The number needed to screen with MRI to prevent 1 missed injury was 21. CONCLUSIONS: The findings suggest that the routine use of MRI in clearing the cervical spine in the obtunded blunt trauma patient.

Observation of the radiative decay mode of the free neutron.

The theory of quantum electrodynamics (QED) predicts that beta decay of the neutron into a proton, electron and antineutrino should be accompanied by a continuous spectrum of soft photons. While this inner bremsstrahlung branch has been previously measured in nuclear beta and electron capture decay, it has never been observed in free neutron decay. Recently, the photon energy spectrum and branching ratio for neutron radiative decay have been calculated using two approaches: a standard QED framework and heavy baryon chiral perturbation theory (an effective theory of hadrons based on the symmetries of quantum chromodynamics). The QED calculation treats the nucleons as point-like, whereas the latter approach includes the effect of nucleon structure in a systematic way. Here we observe the radiative decay mode of free neutrons, measuring photons in coincidence with both the emitted electron and proton. We determined a branching ratio of (3.13 +/- 0.34) x 10(-3) (68 per cent level of confidence) in the energy region between 15 and 340 keV, where the uncertainty is dominated by systematic effects. The value is consistent with the predictions of both theoretical approaches; the characteristic energy spectrum of the radiated photons, which differs from the uncorrelated background spectrum, is also consistent with the calculated spectrum. This result may provide opportunities for more detailed investigations of the weak interaction processes involved in neutron beta decay.