A Short-Term Multicenter Analysis of Radiolucent Lines in a Single Uncemented Rotating Platform Implant for Total Knee Arthroplasty.

Background: Uncemented total knee arthroplasty is increasing as a potential solution for aseptic loosening via biologic fixation and to increase operative efficiency. However, postoperative radiolucent lines (RLLs) remain a concern for some clinicians. We report on a multicenter analysis of these RLLs over a 2-year period to identify their incidence, progression, and clinical significance. Material and methods: Institutional review board approval was obtained for this retrospective, multicenter case series. A total of 312 patients treated with a single cruciate-retaining, fully porous coated femoral and tibial component design were included in the study. All patients were evaluated clinically and radiographically in the early postoperative period and at final follow-up (average 2.0 years). Average age of the study group was 58.2 years, and average body mass index was 30.7. Of the total, 66% were male, and 34% were female. Two independent surgeons evaluated the radiographs at the initial postoperative visit and at the most recent follow-up for RLLs. Knee Society Scores and range of motion (ROM) were collected at each visit. Results: We identified RLLs in 25% of patients. All RLLs were less than 1 mm in size and located at the periphery of the tibial implant. None of the RLLs were progressive. At the final follow-up, compared with early postoperative imaging, no new RLLs were identified. Average ROM in flexion was 124 degrees, and the average Knee Society Scores at the most recent clinical follow-up was 96. Conclusion: RLLs are commonly seen following cementless TKA, most commonly underneath the tibial tray. Based on this data set, there does not appear to be progression of these RLLs with time, and they do not appear to have an effect on ROM or clinical outcome at 2 years.

Buried remnants of the Laurentide Ice Sheet and connections to its surface elevation.

The Laurentide Ice Sheet (LIS) occupied a large part of North-America during the late Pleistocene. Determining the proper surface geometry and elevation of the LIS is of central importance to estimate global changes in sea-level and atmospheric circulation patterns during the late Pleistocene and Holocene. Despite largely disappearing from the landscape during the late Holocene, LIS remnants are found in the Penny and Barnes ice caps on Baffin Island (Canada) and ongoing permafrost degradation has been exposing relics of the LIS buried along its northern margin since the late Pleistocene. Here, we use the δ18O records of six LIS remnants and the late Pleistocene δ18O-elevation relation to establish ice elevation in their source area during the last glacial maximum (LGM). Contrary to some modeled reconstructions, our findings indicate an asymmetric LIS topography with higher ice on Keewatin Dome (~3200 m) and thinner ice in the prairies along the Plains divide (1700-2100 m) during LGM. The resiliency of icy permafrost to past warm intervals preserved relics of the LIS; these ice-marginal landscapes, now poised for thaw, should uncover more valuable clues about the conditions of the last major ice sheet on Earth.

High Arctic Holocene temperature record from the Agassiz ice cap and Greenland ice sheet evolution.

We present a revised and extended high Arctic air temperature reconstruction from a single proxy that spans the past ∼12,000 y (up to 2009 CE). Our reconstruction from the Agassiz ice cap (Ellesmere Island, Canada) indicates an earlier and warmer Holocene thermal maximum with early Holocene temperatures that are 4-5 °C warmer compared with a previous reconstruction, and regularly exceed contemporary values for a period of ∼3,000 y. Our results show that air temperatures in this region are now at their warmest in the past 6,800-7,800 y, and that the recent rate of temperature change is unprecedented over the entire Holocene. The warmer early Holocene inferred from the Agassiz ice core leads to an estimated ∼1 km of ice thinning in northwest Greenland during the early Holocene using the Camp Century ice core. Ice modeling results show that this large thinning is consistent with our air temperature reconstruction. The modeling results also demonstrate the broader significance of the enhanced warming, with a retreat of the northern ice margin behind its present position in the mid Holocene and a ∼25% increase in total Greenland ice sheet mass loss (∼1.4 m sea-level equivalent) during the last deglaciation, both of which have implications for interpreting geodetic measurements of land uplift and gravity changes in northern Greenland.

Ice Core Perspective on Mercury Pollution during the Past 600 Years.

Past emissions of the toxic metal mercury (Hg) persist in the global environment, yet these emissions remain poorly constrained by existing data. Ice cores are high-resolution archives of atmospheric deposition that may provide crucial insight into past atmospheric Hg levels during recent and historical time. Here we present a record of total Hg (HgT) in an ice core from the pristine summit plateau (5340 m asl) of Mount Logan, Yukon, Canada, representing atmospheric deposition from AD 1410 to 1998. The Colonial Period (∼1603-1850) and North American "Gold Rush" (1850-1900) represent minor fractions (8% and 14%, respectively) of total anthropogenic Hg deposition in the record, with the majority (78%) occurring during the 20th Century. A period of maximum HgT fluxes from 1940 to 1975 coincides with estimates of enhanced anthropogenic Hg emissions from commercial sources, as well as with industrial emissions of other toxic metals. Rapid declines in HgT fluxes following peaks during the Gold Rush and the mid-20th Century indicate that atmospheric Hg deposition responds quickly to reductions in emissions. Increasing HgT fluxes from 1993 until the youngest samples in 1998 may reflect the resurgence of Hg emissions from unregulated coal burning and small-scale gold mining.

Differential neuroprotective and anti-inflammatory effects of L-type voltage dependent calcium channel and ryanodine receptor antagonists in the substantia nigra and locus coeruleus.

Neuroinflammation and degeneration of catecholaminergic brainstem nuclei occur early in neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Neuroinflammation increases levels of pro-inflammatory cytokines and reactive oxygen species which can alter neuronal calcium (Ca(+2)) homoeostasis via L-type voltage dependent calcium channels (L-VDCCs) and ryanodine receptors (RyRs). Alterations in Ca(+2) channel activity in the SN and LC can lead to disruption of normal pacemaking activity in these areas, contributing to behavioral deficits. Here, we utilized an in vivo model of chronic neuroinflammation: rats were infused intraventricularly with a continuous small dose (0.25 µg/h) of lipopolysaccharide (LPS) or artificial cerebrospinal fluid (aCSF) for 28 days. Rats were treated with either the L-VDCC antagonist nimodipine or the RyR antagonist dantrolene. LPS-infused rats had significant motor deficits in the accelerating rotarod task as well as abnormal behavioral agitation in the forced swim task and open field. Corresponding with these behavioral deficits, LPS-infused rats also had significant increases in microglia activation and loss of tyrosine hydroxylase (TH) immunoreactivity in the substantia nigra pars compacta (SNpc) and locus coeruleus (LC). Treatment with nimodipine or dantrolene normalized LPS-induced abnormalities in the rotarod and forced swim, restored the number of TH-immunoreactive cells in the LC, and significantly reduced microglia activation in the SNpc. Only nimodipine significantly reduced microglia activation in the LC, and neither drug increased TH immunoreactivity in the SNpc. These findings demonstrate that the Ca(+2) dysregulation in the LC and SN brainstem nuclei is differentially altered by chronic neuroinflammation. Overall, targeting Ca + 2 dysregulation may be an important target for ameliorating neurodegeneration in the SNpc and LC.

Total hip and knee replacement in a patient with arthrogryposis multiplex congenita.

Arthrogryposis multiplex congenita (AMC) is a complex disorder that leads to joint stiffness and deformities in 2 or more joints in afflicted children. Late manifestations of this disorder can include secondary degeneration of the abnormal joints with arthritic symptoms of pain and loss of function. There are few reports in the orthopedic literature on the use of total joint arthroplasty to improve the pain and function in patients with arthrogryposis. This case report presents one patient who underwent bilateral total hip and total knee arthroplasties for deteriorating function and pain in her hips and knees secondary to the congenital deformities created by arthrogryposis multiplex congenita. We discuss the intraoperative difficulties and techniques used to reconstruct her hips and knees, as well as the potential indications for joint arthroplasty in this challenging group of patients.

Five- to ten-year outcomes for modular metal-on-metal total hip arthroplasty.

In recent years, metal-on-metal (MOM) arthroplasty has come under fire with reported adverse outcomes of metal hypersensitivity, adverse local tissue reaction (ALTR), and the carcinogenicity concern from systemic metal ions. We present a retrospective analysis of 354 primary total hip arthroplasties from 2 independent centers. Revision data, predicted survival and Harris Hip Scores (HHS) are reported. Nine hips (2.5%) underwent component revision, and 9 year predicted survival was 95.8%. One revision had elevated metal ions but no histological evidence of ALTR. Average HHS at a minimum 5 year follow up (range 5-10 years) improved significantly from 52 pre-operatively to 93 post-operatively. While a 2.5% revision rate and improved clinical outcomes are reported in this study, longer term follow-up is warranted to monitor for late complications.

Efficacy of post exposure administration of doxycycline in a murine model of inhalational melioidosis.

Burkholderia pseudomallei is the causative agent of melioidosis. Treatment of melioidosis is suboptimal and developing improved melioidosis therapies requires animal models. In this report, we exposed male BALB/c mice to various amounts of aerosolized B. pseudomallei 1026b to determine lethality. After establishing a median lethal dose (LD(50)) of 2,772 colony forming units (cfu)/animal, we tested the ability of doxycycline administered 6 hours after exposure to a uniformly lethal dose of ~20 LD(50) to prevent death and eliminate bacteria from the lung and spleens. Tissue bacterial burdens were examined by PCR analysis. We found that 100% of mice treated with doxycycline survived and B. pseudomallei DNA was not amplified from the lungs or spleens of most surviving mice. We conclude the BALB/c mouse is a useful model of melioidosis. Furthermore, the data generated in this mouse model indicate that doxycycline is likely to be effective in post-exposure prophylaxis of melioidosis.

Inhalational monkeypox virus infection in cynomolgus macaques.

An inhalation exposure system was characterized to deliver aerosolized monkeypox virus (MPXV), and a non-human primate (NHP) inhalation monkeypox model was developed in cynomolgus macaques. A head-only aerosol exposure system was characterized, and two sampling methods were evaluated: liquid impingement via an impinger and impaction via a gelatin filter. The aerosol concentrations obtained with the gelatin filter and impinger were virtually identical, indicating that either method is acceptable for sampling aerosols containing MPXV. The mass median aerodynamic diameter (MMAD) for individual aerosol tests in the aerosol system characterization and the NHP study ranged from 1.08 to 1.15 µm, indicating that the aerosol particles were of a sufficient size to reach the alveoli. Six cynomolgus macaques (four male and two female) were used on study. The animals were aerosol exposed with MPXV and received doses between 2.51 × 10(4) to 9.28 × 10(5) plaque forming units (PFUs) inhaled. Four of the six animals died or were euthanized due to their moribund conditions. Both animals that received the lowest exposure doses survived to the end of the observation period. The inhalation LD(50) was determined to be approximately 7.8 × 10(4) pfu inhaled. These data demonstrate that an inhalation MPXV infection model has been developed in the cynomolgus macaque with disease course and lethal dose similar to previously published data.

The pathophysiology of inhalational brucellosis in BALB/c mice.

To characterize the clinical presentation and pathophysiology of inhalational brucellosis, Balb/c mice were challenged with Brucella melitensis 16M in a nose-only aerosol exposure chamber. A low dose of 1000 cfu/animal of B. melitensis resulted in 45% of mice with tissue burdens eight weeks post-challenge. The natural history of brucellosis in mice challenged by higher aerosol doses was examined by serial euthanizing mice over an eight week period. Higher challenge doses of 1.00E+05 and 5.00E+05 cfu resulted in positive blood cultures 14 days post-challenge and bacterial burdens were observed in the lung, liver and/or spleens 14 days post-challenge. In addition, the progression of brucellosis was similar between mice challenged by the intranasal and aerosol routes. The results from this study support the use of the Balb/c aerosol nose-only brucellosis mouse model for the evaluation of therapeutics against inhalational brucellosis.

Pathophysiology of the rhesus macaque model for inhalational brucellosis.

The objective of this study was to characterize the rhesus macaque (RM) as a model for inhalational brucellosis in support of the U.S. Food and Drug Administration's (FDA) Animal Rule. The pathophysiology of chronic Brucella melitensis aerosol infection was monitored in two phases that each occurred over an 8-week time period; dose escalation (8 RMs; targeted doses of 5.0E+03, 5.0E+04, or 5.0E+05 CFU/animal or the unchallenged control) and natural history (12 RMs; targeted dose of 2.50E+05 CFU/animal or the unchallenged control). RMs given an aerosol challenge with B. melitensis developed undulating fevers (6/6 phase I; 8/9 phase II), positive enriched blood cultures (5/10; phase II), and bacterial burdens in tissues starting 14 to 21 days postchallenge (6/6 phase I; 10/10 phase II). In addition, 80% (8/10; phase II) of infected RMs seroconverted 14 to 21 days postchallenge. RMs developed elevations in certain liver enzymes and had an increased inflammatory response by 3 weeks postchallenge as shown by increases in C-reactive protein (6/8) and neopterin (4/8), which correlated with the onset of a fever. As early as 14 days postchallenge, positive liver biopsy specimens were detected (2/8), and ultrasound imaging showed the development of splenomegaly. Finally, histopathologic examination found lesions attributed to Brucella infection in the liver, kidney, lung, and/or spleen of all animals. The disease progression observed with the RMs in this study is analogous to human brucellosis pathophysiology. Thus, the results from this study support the use of the RM as an animal model for inhalational brucellosis to evaluate the efficacy of novel vaccines and therapeutics against B. melitensis.

Reconstructed changes in Arctic sea ice over the past 1,450 years.

Arctic sea ice extent is now more than two million square kilometres less than it was in the late twentieth century, with important consequences for the climate, the ocean and traditional lifestyles in the Arctic. Although observations show a more or less continuous decline for the past four or five decades, there are few long-term records with which to assess natural sea ice variability. Until now, the question of whether or not current trends are potentially anomalous has therefore remained unanswerable. Here we use a network of high-resolution terrestrial proxies from the circum-Arctic region to reconstruct past extents of summer sea ice, and show that-although extensive uncertainties remain, especially before the sixteenth century-both the duration and magnitude of the current decline in sea ice seem to be unprecedented for the past 1,450 years. Enhanced advection of warm Atlantic water to the Arctic seems to be the main factor driving the decline of sea ice extent on multidecadal timescales, and may result from nonlinear feedbacks between sea ice and the Atlantic meridional overturning circulation. These results reinforce the assertion that sea ice is an active component of Arctic climate variability and that the recent decrease in summer Arctic sea ice is consistent with anthropogenically forced warming.

Comparison of radiographic alignment of imageless computer-assisted surgery vs conventional instrumentation in primary total knee arthroplasty.

A total of 208 patients were enrolled in a multicenter, prospective randomized, institutional review board-approved study that compared preoperative surgical plan to postoperative 2-dimensional radiographic alignment measured by a blinded reviewer for primary total knee arthroplasty (TKA) implanted using computer-assisted surgery (CAS) compared with conventional TKA instrumentation. The results demonstrated a statistically significant improvement in the coronal tibial component alignment (P < .03) and failed to demonstrate a statistically significant improvement in the mechanical axis, femoral coronal/sagittal, and tibial sagittal alignment. Knee Society Score knee and function scores and 6-minute walk test were equivalent between the 2 treatment groups at all postoperative intervals. There was a statistically significant increase in the skin-skin time (P < .0001) and the time until first bone cut (P < .0001) for the CAS knees compared with those implanted with conventional instrumentation. The use of CAS in this randomized clinical trial conducted at high-volume centers did not offer a clinically meaningful improvement in postoperative alignment, clinical, functional, or safety outcomes compared with conventional TKA.

Rotating platform spinouts with cruciate-retaining mobile-bearing knees.

Spinout or dislocation is a complication of mobile-bearing total knee arthroplasty. We have observed this complication in 7 of 1255 cruciate-retaining mobile-bearing total knees (0.56%). Patient factors associated with a spinout included female sex, obesity, and preoperative valgus deformity. Operative treatment was generally successful, but significant complications occurred in 3 of the 7 patients.

A randomized, prospective study of total hip wound closure with resorbable subcuticular staples.

Resorbable subcuticular staples are a new way to close surgical wounds and have not been reported in the orthopedic literature. This randomized, controlled study compared a resorbable subcuticular staple system with stainless steel wound stapling in patients undergoing unilateral primary total hip arthroplasty (THA). Institutional Review Board approval and patient consent was obtained for all patients. Sixty patients (30 each group) were randomized to receive either resorbable subcuticular staples or stainless steel staples after primary THA. Incision length, number of staples used, and any staple insertion problems were recorded. Subjective reports of pain levels or incision complaints were solicited, and wound photographs were obtained on days 1 and 14 and 6 weeks postoperatively. The presence of wound drainage, erythema, wound separation, or echymosis was recorded at each visit, as well as all postoperative complications. The average incision length in the resorbable group was 13.2 cm and required 16 staples for closure, compared to 15 cm and 20 staples for the metal staple group. No infections occurred in either group, although the incidence of erythema and wound drainage at 2 weeks was higher for patients in the stainless steel group. One patient with metal staples had a postoperative hematoma requiring secondary irrigation and debridement. Patient satisfaction was higher with the resorbable staples. A resorbable subcuticular staple system can provide comparable wound closure to stainless steel staples following THA and may do so with less local discomfort, wound drainage, or erythematous reaction.

Unicompartmental and total knee arthroplasty in the over 70 population.

This retrospective study compares the short-term outcomes of small-incision unicompartmental knee arthroplasty (41 patients) with standard total knee arthroplasty (TKA) (50 patients) in 91 consecutive patients older than 70 years. Knee Society Scores and range of motion (ROM) were assessed preoperatively, at 6 weeks and 6 months, and through a minimum of 2 years. Postoperative comparisons included blood loss, transfusions, narcotic consumption, length of hospital stay, and complications. While Knee Scores and ROM were similar preoperatively, both were better in the unicompartmental group at each postoperative time interval. Patients with unicompartmental replacements had a much quicker return of function and discontinuation of pain medication. Blood loss was significantly more for the TKA group, as was the need for blood transfusion. None of the unicompartmental patients required transfusion. Narcotic use and length of hospital stay were also significantly less for the unicompartmental group. The overall rate of postoperative medical and surgical complications was similar for the 2 groups, with 1 major complication in each. Overall, the physiologic impact of unicompartmental knee arthroplasty was much less than TKA in this older patient population and resulted in a faster recovery.

Unicompartmental knee arthroplasty compares favorably to total knee arthroplasty in the same patient.

There are several surgical management options for medial knee arthritis, and it is often difficult to decide whether a unicompartmental knee arthroplasty (UKA) or total knee arthroplasty (TKA) is appropriate. Few studies have compared UKAs and TKAs in the same patient. We identified 23 patients with osteoarthritis who had a TKA on one side and a UKA on the other. The preoperative values of the 2 knees were not statistically different. Strict criteria were used to determine whether a UKA could be performed (functional anterior cruciate ligament, minimal deformity, and minimum changes in other compartments). Preoperative radiographs were reviewed to confirm that the knee undergoing TKA had medial compartment disease only. Knee Society scores, radiographic analysis, and patient preferences were recorded for all patients. Average follow-up was 46 months (range, 7.2-148 months) and 42 months (range, 11.5-59.8 months) for TKA and UKA, respectively. We found little or no difference in outcomes between the 2 procedures, except for an improved range of motion with the UKA compared with the TKA (123 degrees +/-9 degrees vs 119.8 degrees +/-7 degrees, respectively). Knee Society scores improved from 45.9 to 89.7 in UKA and from 42.4 to 90.3 in TKA. Of the 23 patients, 11 expressed no preference between either knee and 12 preferred the unicompartmental knee; no patient preferred the total knee. With appropriate patient selection, UKAs are a successful option for patients with osteoarthritis.