Grass veins are leaky pipes: vessel widening in grass leaves explain variation in stomatal conductance and vessel diameter among species.

The widening of xylem vessels from tip to base of trees is an adaptation to minimize the hydraulic resistance of a long pathway. Given that parallel veins of monocot leaves do not branch hierarchically, vessels should also widen basipetally but, in addition to minimizing resistance, should also account for water volume lost to transpiration since they supply water to the lamina along their lengths, that is 'leakiness'. We measured photosynthesis, stomatal conductance, and vessel diameter at five locations along each leaf of five perennial grass species. We found that the rate of conduit widening in grass leaves was larger than the widening exponent required to minimize pathlength resistance (0.35 vs c. 0.22). Furthermore, variation in the widening exponent among species was positively correlated with maximal stomatal conductance (r2 = 0.20) and net CO2 assimilation (r2 = 0.45). These results suggest that faster rates of conduit widening (> 0.22) were associated with higher rates of water loss. Taken together, our results show that the widening exponent is linked to plant function in grass leaves and that natural selection has favored parallel vein networks that are constructed to meet transpiration requirements while minimizing hydraulic resistance within grass blades.

To wean or not to wean: proton pump inhibitor management after anti-reflux surgery amongst foregut experts.

BACKGROUND: Most patients undergoing anti-reflux surgery (ARS) have a history of preoperative proton pump inhibitor (PPI) use. It is well-established that ARS is effective in restoring the anti-reflux barrier, eliminating the ongoing need for costly PPIs. Current literature lacks objective evidence supporting an optimal postoperative PPI cessation or weaning strategy, leading to wide practice variations. We sought to objectively gauge current practice and opinion surrounding the postoperative management of PPIs among expert foregut surgeons and gastroenterologists in the United States. METHODS: We created a survey of postoperative PPI management protocols, with an emphasis on discontinuation and timing of PPI cessation, and aimed to determine what factors played a role in the decision-making. An electronic survey tool (Qualtrics XM, Qualtrics, Provo, UT) was used to distribute the survey and to record the responses anonymously for a period of three months. RESULTS: The survey was viewed 2658 times by 373 institutions and shared with 644 members. In total, 121 respondents participated in the survey and 111 were surgeons (92%). Fifty respondents (42%) always discontinue PPIs immediately after ARS. Of the remaining 70 respondents (58%), 46% always wean or taper PPIs postoperatively and 47% wean or taper them selectively. The majority (92%) of practitioners taper within a 3-month period postoperatively. Five respondents never discontinue PPIs after ARS. Overall, only 23 respondents (19%) stated their protocol is based on medical literature or evidence-based medicine. Instead, decision-making is primarily based on anecdotal evidence/personal preference (42%, n = 50) or prior training/mentors (39%, n = 47). CONCLUSIONS: There are two major protocols used for PPI discontinuation after ARS: Nearly half of providers abruptly stop PPIs, while just over half gradually tapers them, most often in the early postoperative period. These decisions are primarily driven by institutional practices and personal preferences, underscoring the need for evidence-based recommendations.

Trajectories of prescription opioid tapering in patients with chronic non-cancer pain: a retrospective cohort study, 2015-2020.

OBJECTIVE: To identify common opioid tapering trajectories among patients commencing opioid taper from long-term opioid therapy for chronic non-cancer pain and to examine patient-level characteristics associated with these different trajectories. DESIGN: A retrospective cohort study. SETTING: Australian primary care. SUBJECTS: Patients prescribed opioid analgesics between 2015 and 2020. METHODS: Group-based trajectory modeling and multinomial logistic regression analysis were conducted to determine tapering trajectories and to examine demographic and clinical factors associated with the different trajectories. RESULTS: A total of 3369 patients commenced a taper from long-term opioid therapy. Six distinct opioid tapering trajectories were identified: low dose / completed taper (12.9%), medium dose / faster taper (12.2%), medium dose / gradual taper (6.5%), low dose / noncompleted taper (21.3%), medium dose / noncompleted taper (30.4%), and high dose / noncompleted taper (16.7%). A completed tapering trajectory from a high opioid dose was not identified. Among patients prescribed medium opioid doses, those who completed their taper were more likely to have higher geographically derived socioeconomic status (relative risk ratio [RRR], 1.067; 95% confidence interval [CI], 1.001-1.137) and less likely to have sleep disorders (RRR, 0.661; 95% CI, 0.463-0.945) than were those who didn't complete their taper. Patients who didn't complete their taper were more likely to be prescribed strong opioids (eg, morphine, oxycodone), regardless of whether they were tapered from low (RRR, 1.444; 95% CI, 1.138-1.831) or high (RRR, 1.344; 95% CI, 1.027-1.760) doses. CONCLUSIONS: Those prescribed strong opioids and high doses appear to be less likely to complete tapering. Further studies are needed to evaluate the clinical outcomes associated with the identified trajectories.

Auricular Acupressure Adjunct Treatment for Opioid Tapering: A Randomized Pilot Feasibility Study.

PURPOSE: Opioid medications are necessary in the treatment of critically ill infants; however. prolonged use may lead to withdrawal syndrome. The purpose of this study was to assess feasibility of delivering an acupressure protocol for the treatment of iatrogenic withdrawal in a pediatric cardiac intensive care unit as well as impact and acceptance of acupressure as an adjunct treatment. DESIGN: Randomized pilot feasibility trial. METHODS: Acupressure stickers were applied and rotated to one ear every 1-3 days until withdrawal symptoms improved. RESULTS: There were no serious adverse events, with only one reported incident of skin irritation. Recruiting benchmarks were exceeded. Weaning phases were significantly shorter in the acupressure group (medians 6.0 vs 22.0 respectively, p = .025, d = 0.90) and the control group used skin-to-skin contact as a comfort measure significantly more than the acupressure group (42.9% vs 6.3%, p = .18). Acupressure was accepted by parents, with an overall 96.2% rating their experience as positive, as measured by the Parent Client Satisfaction Questionnaire. The majority of health care providers (n = 19) were supportive, with 71.9% agreeing or completely agreeing acupressure is an acceptable adjunct for the treatment of withdrawal symptoms; 26.8% were neutral, as measured by the Acceptability of Intervention Measure, Intervention Appropriateness Measure, and Feasibility of Intervention Measure. CONCLUSIONS: Acupressure was found to be safe, feasible, and accepted by health care providers in a pediatric cardiac intensive care setting. CLINICAL IMPLICATIONS: These findings support future research with larger sample sizes to improve clinical treatment of infants physically dependent on sedative medications.

Methylprednisolone taper is an effective addition to multimodal pain regimens after total shoulder arthroplasty: results of a randomized controlled trial: 2022 Neer Award winner.

BACKGROUND: Perioperative corticosteroids have shown potential as nonopioid analgesic adjuncts for various orthopedic pathologies, but there is a lack of research on their use in the postoperative setting after total shoulder arthroplasty (TSA). The purpose of this study was to assess the effect of a methylprednisolone taper on a multimodal pain regimen after TSA. METHODS: This study was a randomized controlled trial (clinicaltrials.gov NCT03661645) of opioid-naive patients undergoing TSA. Patients were randomly assigned to receive intraoperative dexamethasone only (control group) or intraoperative dexamethasone followed by a 6-day oral methylprednisolone (Medrol) taper course (treatment group). All patients received the same standardized perioperative pain management protocol. Standardized pain journal entries were used to record visual analog pain scores (VAS-pain), VAS-nausea scores, and quantity of opioid tablet consumption during the first 7 postoperative days (POD). Patients were followed for at least one year postoperatively for clinical evaluation, collection of patient-reported outcomes, and observation of complications. RESULTS: A total of 67 patients were enrolled in the study; 32 in the control group and 35 in the treatment group. The groups had similar demographics and comorbidities. The treatment group demonstrated a reduction in mean VAS pain scores over the first 7 POD. Between POD 1 and POD 7, patients in the control group consumed an average of 17.6 oxycodone tablets while those in the treatment group consumed an average of 5.5 tablets. This equated to oral morphine equivalents of 132.1 and 41.1 for the control and treatment groups, respectively. There were fewer opioid-related side effects during the first postoperative week in the treatment group. The treatment group reported improved VAS pain scores at 2-week, 6-week, and 12-week postoperatively. There were no differences in Europe Quality of Life, shoulder subjective value (SSV), at any time point between groups, although American Shoulder and Elbow Surgeons questionnaire scores showed a slight improvement at 6-weeks in the treatment group. At mean follow-up, (control group: 23.4 months; treatment group:19.4 months), there was 1 infection in the control group and 1 postoperative cubital tunnel syndrome in the treatment group. No other complications were reported. CONCLUSIONS: A methylprednisolone taper course shows promise in reducing acute pain and opioid consumption as part of a multimodal regimen following TSA. As a result of this study, we have included this 6-day methylprednisolone taper course in our multimodal regimen for all primary shoulder arthroplasties. We hope this trial serves as a foundation for future studies on the use of low-dose oral corticosteroids and other nonnarcotic modalities to control pain after shoulder surgeries.

Systematic Review and Meta-Analysis of Studies Comparing the Rate of Post-operative Periprosthetic Fracture Following Hip Arthroplasty With a Polished Taper Slip versus Composite Beam Stem.

BACKGROUND: We compared the incidence of postoperative periprosthetic femoral fractures (POPFF) following hip arthroplasty with either a cemented polished taper slip (PTS) stem or a cemented composite beam (CB) stem in comparative studies. METHODS: A systematic review of comparative studies, written in English and published in peer-reviewed journals since the year 2000, was conducted. Study quality was assessed using the Newcastle-Ottawa scale.The overall study qualities were good. There were 913,021 patients from 18 cohorts included in the meta-analysis. There were 294,540 patients who received a CB stem and 618,481 received a PTS stem. Cohorts were classified as high- or low-risk for POPFF based on patient risk factors. A metanalysis was performed using a random effects model, and the relative incidence with 95% confidence intervals (CIs) was reported. RESULTS: The patients at low risk of POPFF had an incidence rate ratio of 3.14 (CI: 2.48, 3.98) for the PTS group versus the CB group. Whereas, the patients at high risk of POPFF had an incidence rate ratio of 9.87 (CI: 3.63, 26.80) for the PTS group versus the CB group. CONCLUSIONS: The risk of POPFF is lower when hip arthroplasty was performed using a CB stem versus a PTS stem. This protective effect was greatest in patients who had a higher risk of POPFF. Surgeons should consider the effect of cemented stem choice on the risk of subsequent periprosthetic femur fracture, particularly in frail or elderly patients who are at a higher risk of postoperative periprosthetic femoral fracture.

New Ceramic Heads With Titanium Sleeves on Retained Femoral Components: Results of Over 500 Revision Total Hip Arthroplasties.

BACKGROUND: Ceramic heads are frequently combined with titanium sleeves in revision total hip arthroplasties (THAs), ostensibly to protect the ceramic head from existing damage to the retained trunnion. Although widely adopted, data on the performance and safety of this construct are minimal. The purpose of this study was to describe implant survivorships, radiographic results, and clinical outcomes of patients who underwent revision THA with a ceramic head and titanium sleeve on a retained femoral component. METHODS: We identified 516 revision THAs with femoral component retention (328 acetabular-only revisions and 188 bearing surface exchanges) treated with a new ceramic head and titanium sleeve between 2000 and 2020. Mean age at revision was 64 years, 56% were women, and mean body mass index was 30. The indications for revision THA were adverse local tissue reaction (25%), acetabular loosening (24%), dislocation (17%), infection (5%), and other (29%). Kaplan-Meier survivorships were analyzed, radiographs reviewed, and Harris Hip Scores evaluated. Mean follow-up was 4 years (range, 2 to 10). RESULTS: There were no reoperations or failures for ceramic head fracture, taper corrosion, or head/sleeve disengagement. The 10-year survivorship free of any re-revision was 85%. Indications for the 57 re-revisions included dislocation (33), infection (13), acetabular component loosening (7), periprosthetic fracture (2), psoas impingement (1), and sciatic nerve irritation (1). The 10-year survivorship free of any reoperation was 82%. There were an additional 14 reoperations. Radiographically, 1.9% had progressive femoral radiolucent lines, and 4.7% had progressive acetabular radiolucent lines. Mean Harris Hip Score was 81 at 2 years. CONCLUSIONS: New ceramic heads with titanium sleeves in revision THAs with retained femoral components were durable and reliable with no cases of ceramic head fracture or taper complications at mean 4-year follow-up, including those revised for adverse local tissue reaction. LEVEL OF EVIDENCE: IV.

Experimental periprosthetic fractures with collarless polished tapered cemented stems.

PURPOSE: After cemented total hip arthroplasty, the risk of periprosthetic fracture (PPF) of taper-slip stems is higher than that of composite-beam stems. We aimed to assess the conditions resulting in PPFs of taper-slip stems using a falling weight. METHODS: Taper-slip stems were fixed to five types of simulated bone models using bone cement, and the fractures were evaluated by dropping stainless-steel weights from a predetermined height onto the heads. The periprosthetic fracture height in 50% of the bone models (PPFH50) was calculated using the staircase method. RESULTS: For the fixation with 0° of flexion, the values for PPFH50 were 61 ± 11, 60 ± 13, above 110, 108 ± 49, and 78 ± 12 cm for the cobalt-chromium-molybdenum alloy, stainless steel alloy (SUS), titanium alloy (Ti), smooth surface, and thick cement mantle models, respectively; for the fixation with 10° of flexion (considering flexure), the PPFH50 values were 77 ± 5, 85 ± 9, 90 ± 2, 89 ± 5, and 81 ± 11 cm, respectively. The fracture rates of the polished-surface stems were 78.6 and 35.7% at the proximal and distal sites, respectively (p < 0.05); the fracture rates of the smooth-surface stems were 14.2 and 100%, respectively (p < 0.05). CONCLUSION: The impact tests demonstrated that the conditions that were less likely to cause PPFs were use of Ti, a smooth surface, a thick cement mantle, and probably, use of SUS.

Long stem revision versus short stem revision with plate osteosynthesis for Vancouver type B2 periprosthetic femoral fracture: a comparative study of eighty five cases.

PURPOSE: Periprosthetic femoral fractures (PPFs) around the hip are challenging complications in orthopaedic surgery, particularly Vancouver type B2 (VTB2) fractures. The surgical management of these fractures is crucial and depends on various factors. Cementless short taper stem with plate osteosynthesis is an alternative surgical technique. This study aims to compare the outcomes of this surgical technique with revision arthroplasty (RA) with long stem in the treatment of VTB2 PPFs. METHODS: This retrospective study was conducted in a single medical institute from February 2010 to May 2019. Patients who had received either total hip arthroplasty or bipolar hemiarthroplasty and subsequently developed a VTB2 PPF were included; patients who sustained intra-operative fractures or received a cemented stem previously were excluded from the analysis. The patients were divided into two groups: group I received RA with cementless long stem, while group II underwent RA with cementless short taper stem with plate osteosynthesis. Demographic data, radiographic and functional outcomes, and complications were analyzed between the two groups. RESULTS: A total of 85 patients diagnosed with VTB2 PPFs were included in the study. There were no significant differences between the two groups in terms of demographic data, including age, gender, mean follow-up times, estimated blood loss, and operative times. The radiographic results showed that there was no significant difference in the incidence of subsidence and implant stability between the two groups. However, group II tended to have less subsidence and periprosthetic osteolysis. Patients in group II had significantly better functional scores (mean Harris hip score: post-operative: 60.2 in group I and 66.7 in group ii; last follow-up: 77.4 in group 1 and 83.2 in group II (both p < 0.05)). There were no significant differences in the overall complication rate, including infection, dislocation, re-fracture, and revision surgery, between the two groups. CONCLUSIONS: Both surgical techniques, cementless long stem and cementless short taper stem with plate osteosynthesis, are effective in the treatment of Vancouver B2 PPFs, with no significant differences in outcomes or complications. However, patients in cementless short taper stem with plate osteosynthesis had better functional scores at both post-operative and the last follow-up.

The influence of surgical technique guidance and surgeon's experience on the femoral head assembly in total hip arthroplasty.

INTRODUCTION: The importance of the assembly procedure on the taper connection strength is evident. However, existent surgical technique guides frequently lack comprehensive and precise instructions in this regard. The aim of our experimental study was to evaluate the influence of the surgical technique guide on the femoral head assembly procedure in surgeons with differing levels of experience in total hip arthroplasty. MATERIALS AND METHODS: Twenty-eight participants, divided into four groups based on their lifetime experience in total hip arthroplasty, conducted a femoral head assembly procedure in a simulated intraoperative environment before and after reviewing the surgical technique guide. Demographic information and the number of hammer blows were documented. Hammer velocity and impaction angle were recorded using an optical motion capturing system, while the impaction force was measured using a dynamic force sensor within the impactor. RESULTS: We observed a high variation in the number of hammer blows, maximum force, and impaction angle. Overall, the number of hammer blows decreased significantly from 3 to 2.2 after reviewing the surgical technique guide. The only significant intragroup difference in the number of hammer blows was observed in the group with no prior experience in total hip arthroplasty. No correlation was found between individual factors (age, weight, height) or experience and the measured parameters (velocity, maximum force and angle). CONCLUSIONS: The present study demonstrated a high variation in the parameters of the femoral head assembly procedure. Consideration of the surgical technique guide was found to be a limited factor among participants with varying levels of experience in total hip arthroplasty. These findings underline the importance of sufficient preoperative training, to standardize the assembly procedure, including impaction force, angle, and use of instruments.

Femoral revision in total hip arthroplasty using a cementless modular stem: clinical and radiological results with a 8-year follow-up.

INTRODUCTION: Modular femoral components allow for patient-specific restoration of hip joint geometry and the reconstruction of extensive bone defects in revision total hip arthroplasty (THA); however, potential problems of modular implants such as taper corrosion and the risk of implant fracture continue to be of concern. The aim of the present study was to evaluate the clinical and radiological results of a cementless modular revision stem following revision surgery due to aseptic loosening and periprosthetic fracture and to assess patient-reported outcome measures (PROMs) in these patients at mid-term follow-up. MATERIALS AND METHODS: In this study, a consecutive cohort of 75 patients who underwent primary revision THA at our institution using a modular cementless stem design (MRP-TITAN stem) was retrospectively evaluated at a mean follow-up of 7.7 years. Kaplan-Meier survivorship analyses were performed with revision of the femoral component for any reason as the end point. The Harris-Hip Score, the UCLA Activity Score, the Forgotten Joint Score and the SF-12 Score were used for clinical assessment. We used the Wilcoxon signed rank test to compare pre- and postoperative clinical scores. RESULTS: Overall stem survival with the endpoint stem re-revision for any reason was 85.4% at a mean follow-up of 7.7 years (range 2.4-14 years). Stem survival was 89.5% in the aseptic loosening group and 78.3% in the periprosthetic fracture group with no statistically significant difference between both groups (p = 0.107). One patient had to be revised due to taper fracture. PROMs improved significantly up to the latest follow-up, and radiographic evaluation showed full osseointegration of all stems in this cohort. CONCLUSIONS: Revision THA using a modular cementless titanium revision stem demonstrated adequate clinical and radiological results at mid- to long-term follow-up in this cohort. Cementless revision stems are a useful treatment option to restore the anatomy, especially in deformed hips and in complex revision hip arthroplasty. However, there are some significant disadvantages related to an increased risk of mechanical failure such as corrosion/fretting damage and implant fracture. Future high-quality prospective studies with longer follow-up are necessary to confirm the supposed advantages.

A real-world 2-year prospective study of medication tapering in patients with well-controlled rheumatoid arthritis within the rheumatoid arthritis medication tapering (RHEUMTAP) cohort.

OBJECTIVES: This study had two aims: (i) to investigate outcomes of medication tapering in stable RA patients on biologic or targeted synthetic disease-modifying anti-rheumatic drugs (bDMARDs/tsDMARDs) and conventional synthetic DMARDs (csDMARDs) in a real-world prospective cohort; and (ii) to evaluate possible predictors of flare with medication taper. METHODS: A prospective cohort of patients with RA in sustained remission or low disease activity while on stable bDMARD/tsDMARDs +/- csDMARDs for at least 6 months underwent medication tapering/stopping and was tracked for 2 years. Patients were evaluated for flares in four groups: no taper, only bDMARD/tsDMARD taper, only csDMARD taper and both csDMARD and bDMARD/tsDMARD taper. RESULTS: The RHEUMTAP cohort included 131 patients that met eligibility criteria, of which 52 patients underwent a medication taper. Flare was experienced by 15 patients in the taper and two in the no-taper groups. Patients undergoing any taper/stop overall were 10 times more likely to experience a flare compared with those not tapered (HR 10.43, 95% CI 2.98-36.53, P = 0.0002). The group tapering bDMARD/tsDMARD had 31 times higher risk of flare (HR 31.43, 95% CI 6.35-155.55, P <0.0001) than the no-taper group. Patients tapering both csDMARDs and bDMARD/tsDMARDs had 18 times higher risk of flare than the no-taper group (HR 18.45, 95% CI 2.55-133.37, P = 0.0039). The only csDMARD taper group had a 91% lower risk of flare than the bDMARD/tsDMARD taper group (HR 0.09, 95% CI 0.01-0.69, P = 0.0213). CONCLUSION: In our real-world prospective RHEUMTAP cohort study on the outcomes of different medication tapering groups in well-controlled RA, patients who tapered or stopped bDMARDs/tsDMARDs with or without background therapy were more likely to experience a flare than patients that did not taper any medications and those that tapered only csDMARDs.

Deprescribing interventions for gabapentinoids in adults: A scoping review.

The emerging issue of rising gabapentinoid misuse is being recognized alongside the lack of current evidence supporting the safe and effective deprescribing of gabapentinoids. This scoping review aimed to assess the extent and nature of gabapentinoid deprescribing interventions in adults, either in reducing dosages, or prescribing of, gabapentinoids. Electronic databases were searched on 23 February 2022 without restrictions. Eligible studies included randomized, non-randomized and observational studies that assessed an intervention aimed at reducing/ceasing the prescription/use of a gabapentinoid in adults for any indication in a clinical setting. The research outcomes investigated the type of intervention, prescribing rates, cessations, patient outcomes and adverse events. Extracted outcome data were categorized as either short (≤3 months), intermediate (>3 but <12 months) or long (≥12 months) term. A narrative synthesis was conducted. The four included studies were conducted in primary and acute care settings. Interventions were of dose-reducing protocols, education and/or pharmacological-based approaches. In the randomized trials, gabapentinoid use could be ceased in at least one third of participants. In the two observational trials, gabapentinoid prescribing rates decreased by 9%. Serious adverse events and adverse events specifically related to gabapentinoids were reported in one trial. No study included patient-focused psychological interventions in the deprescribing process, nor provided any long-term follow-up. This review highlights the lack of existing evidence in this area. Due to limited available data, our review was unable to make any firm judgements on the most effective gabapentinoid deprescribing interventions in adults, highlighting the need for more research in this area.

Are opioids effective analgesics and is physiological opioid dependence benign? Revising current assumptions to effectively manage long-term opioid therapy and its deprescribing.

A re-examination of clinical principles of long-term opioid therapy (LTOT) for chronic pain is long overdue amid the ongoing opioid crisis. Most patients on LTOT report ineffectiveness (poor pain control, function and health) but still find deprescribing challenging. Although prescribed as analgesics, opioids more likely provide pain relief primarily through reward system actions (enhanced relief and motivation) and placebo effect and less through antinociceptive effects. The unavoidable physiologic LTOT dependence can automatically lead to a paradoxical worsening of pain, disability and medical instability (maladaptive opioid dependence) without addiction due to allostatic opponent neuroadaptations involving reward/antireward and nociceptive/antinociceptive systems. This opioid-induced chronic pain syndrome (OICP) can persist/progress whether LTOT dose is maintained at the same level, increased, decreased or discontinued. Current conceptualization of LTOT as a straightforward long-term analgesic therapy appears incongruous in view of the complex mechanisms of opioid action, LTOT dependence and OICP. LTOT can be more appropriately conceptualized as therapeutic induction and maintenance of an adaptive LTOT dependence for functional improvement irrespective of analgesic benefits. Adaptive LTOT dependence should be ideally used for a limited time to achieve maximum functional recovery and deprescribed while maintaining functional gains. Patients on LTOT should be regularly re-evaluated to identify if maladaptive LTOT dependence with OICP has diminished any functional gains or leads to ineffectiveness. Ineffective LTOT (with maladaptive LTOT dependence) should be modified to make it safer and more effective. An adequately functional life without opioids is the ideal healthy long-term goal for both LTOT initiation and LTOT modification.

Abrupt Discontinuation Versus Taper of Hydrocortisone in Patients With Septic Shock.

BACKGROUND: Although not mentioned in the most recent guidelines, the 2016 Surviving Sepsis Campaign guidelines recommend to taper corticosteroids once vasopressors are no longer needed; however, at the time of publication, there were no studies comparing taper versus abrupt discontinuation of corticosteroids. OBJECTIVES: The purpose of this study was to further evaluate the impact of abrupt versus taper discontinuation of corticosteroids in septic shock. METHODS: This was a retrospective cohort study that included patients who received an initial dose of 200 to 300 mg of hydrocortisone for septic shock. Participants were then divided into "abrupt" and "taper" groups. The primary outcome assessed was hemodynamic instability during taper or within 72 hours of the last corticosteroid dose. Secondary outcomes included intensive care unit (ICU) and hospital length of stay, incidence of hyperglycemia or hypernatremia, and in-hospital mortality. RESULTS: The primary outcome of reinitiation of vasopressor therapy occurred in a larger proportion of patients in the taper group compared with the abrupt group (21.9% vs 10.7%). The ICU length of stay (7.6 days abrupt vs 9 days taper) and hospital length of stay (14.9 vs 15.3 days) were similar between groups. There was a statistically significant increase in patients who experienced hyperglycemia within 24 hours of the last corticosteroid dose in the abrupt group. All other secondary outcomes were similar between groups. CONCLUSIONS: The abrupt discontinuation of hydrocortisone in the treatment of septic shock was associated with a nonstatistically significant 50% absolute reduction in the need for vasopressor reinitiation.

Lowered muscle glycogen reduces body mass with no effect on short-term exercise performance in men.

Performance in short-duration sports is highly dependent on muscle glycogen, but the total degradation is only moderate and considering the water-binding property of glycogen, unnecessary storing of glycogen may cause an unfavorable increase in body mass. To investigate this, we determined the effect of manipulating dietary carbohydrates (CHO) on muscle glycogen content, body mass, and short-term exercise performance. In a randomized and counterbalanced cross-over design, twenty-two men completed two maximal cycle tests of either 1-min (n = 10) or 15-min (n = 12) duration with different pre-exercise muscle glycogen levels. Glycogen manipulation was initiated three days prior to the tests by exercise-induced glycogen depletion followed by ingestion of a moderate (M-CHO) or high (H-CHO) CHO-diet. Subjects were weighed before each test, and muscle glycogen content was determined in biopsies from m. vastus lateralis before and after each test. Pre-exercise muscle glycogen content was lower following M-CHO than H-CHO (367 mmol · kg-1 DW vs. 525 mmol · kg-1 DW, p < 0.00001), accompanied by a 0.7 kg lower body mass (p < 0.00001). No differences were observed in performance between diets in neither the 1-min (p = 0.33) nor the 15-min (p = 0.99) test. In conclusion, pre-exercise muscle glycogen content and body mass were lower after ingesting moderate compared with high amounts of CHO, while short-term exercise performance was unaffected. This demonstrates that adjusting pre-exercise glycogen levels to the requirements of competition may provide an attractive weight management strategy in weight-bearing sports, particularly in athletes with high resting glycogen levels.

Evaluation of the reproducibility of preoperative three-dimensional computed tomography planning for posterolateral approach total hip arthroplasty.

The anteversion of the stem is occasionally intentionally changed by the surgeon for patients with smaller femoral neck anteversion during total hip arthroplasty (THA). However, the reproducibility of preoperative planning with increasing anteversion has been rarely assessed. The present study investigated it using two types of stems. This retrospective study included patients who underwent primary posterolateral THA using taper-wedge (TS group; 73 hips) and anatomical (AS group; 70 hips) stems. Characteristics of sex and age were matched in the two groups by propensity score matching. In both groups, the relationship between the preoperative three-dimensional planning and postoperative stem position, and the relationship between postoperative stem position and femoral neck anteversion (FNA) were evaluated. In the TS group, there were no significant differences in average stem anteversion (SA) between preoperative planning and postoperative placement (36.1° ± 7.0° and 36.6° ± 11.1°, respectively: p = 0.651). The absolute error of SA was 8.1° ± 6.4°. In the AS group, the postoperative SA was significantly smaller than the preoperative planning SA (22.7° ± 11.6° and 30.0° ± 9.3°, respectively: p < 0.001). The absolute error of SA was 9.0° ± 5.8°. The postoperative SA was significantly larger than the FNA in the TS group (36.6° ± 11.1° and 26.3° ± 10.9°, respectively: p < 0.001). However, no significant differences between the two were observed in the AS group (23.7° ± 10.1° and 22.7° ± 11.6°, respectively: p = 0.253). The preoperative planning of intentional increasing anteversion did not show high reproducibility with taper-wedge and anatomical stems. The anatomical stem was placed according to the femoral medullary canal regardless of preoperative planning with increased SA.

Larger-diameter trunnions and bolt-reinforced taper junctions are associated with less tribocorrosion in reverse total shoulder arthroplasty.

BACKGROUND: Morse taper junction tribocorrosion is recognized as an important failure mode in total hip arthroplasty. Although taper junctions are used in almost all shoulder arthroplasty systems currently available in the United States, with large variation in design, limited literature has described comparable analyses of taper damage in these implants. In this study, taper junction damage in retrieved reverse total shoulder arthroplasty (RTSA) implants was assessed and analyzed. METHODS: Fifty-seven retrieved RTSAs with paired baseplate and glenosphere components with Morse taper junctions were identified via database query; 19 of these also included paired humeral stems and trays or spacers with taper junctions. Components were graded for standard damage modes and for fretting and corrosion with a modified Goldberg-Cusick classification system. Medical records and preoperative radiographs were reviewed. Comparative analyses were performed assessing the impact of various implant, radiographic, and patient factors on taper damage. RESULTS: Standard damage modes were commonly found at the evaluated trunnion junctions, with scratching and edge deformation damage on 76% and 46% of all components, respectively. Fretting and corrosion damage was also common, observed on 86% and 72% of baseplates, respectively, and 23% and 40% of glenospheres, respectively. Baseplates showed greater moderate to severe (grade ≥ 3) fretting (43%) and corrosion (27%) damage than matched glenospheres (fretting, 9%; corrosion, 13%). Humeral stems showed moderate to severe fretting and corrosion on 28% and 30% of implants, respectively; matched humeral trays or spacers showed both less fretting (14%) and less corrosion (17%). On subgroup analysis, large-tapered implants had significantly lower summed fretting and corrosion grades than small-tapered implants (P < .001 for both) on glenospheres; paired baseplate corrosion grades were also significantly lower (P = .031) on large-tapered implants. Factorial analysis showed that bolt reinforcement of the taper junction was also associated with less fretting and corrosion damage on both baseplates and glenospheres. Summed fretting and corrosion grades on glenospheres with trunnions (male) were significantly greater than on glenospheres with bores (female) (P < .001 for both). CONCLUSIONS: Damage to the taper junction is commonly found in retrieved RTSAs and can occur after only months of being implanted. In this study, tribocorrosion predominantly occurred on the taper surface of the baseplate (vs. glenosphere) and on the humeral stem (vs. tray or spacer), which may relate to the flexural rigidity difference between the titanium and cobalt-chrome components. Bolt reinforcement and the use of large-diameter trunnions led to less tribocorrosion of the taper junction. The findings of this study provide evidence for the improved design of RTSA prostheses to decrease tribocorrosion.

Minimum 25-Year Results of a Tapered Titanium Porous Plasma Spray Coated Femoral Component.

BACKGROUND: Previous studies have reported excellent results with tapered, titanium, porous plasma-sprayed components in patients undergoing uncemented primary total hip arthroplasty (THA). The purpose of this study was to examine survival and clinical results at a minimum 25-year follow-up. METHODS: We reviewed all patients who underwent primary THA at our center through 1995 with a specific femoral component that was essentially unchanged since its 1984 introduction, except porous coating was continued circumferentially in 1987, a hydroxyapatite-coated option was offered in 1988, and an offset option was added in 1999. There were 332 patients (396 THA) who had a minimum 25-year follow-up (range, 25 to 37). Mean age at surgery was 48 years (range, 21 to 70 years). Mean follow-up in nonfailed patients was 29 years (range, 25 to 37 years). RESULTS: There were 31 femoral revisions (7.8%): 9 infections, 3 failures of ingrowth, 5 aseptic loosening, 8 osteolysis well-fixed, 2 periprosthetic fractures, 2 polyethylene wear with trochanteric avulsion, 1 component breakage, and 1 malalignment well-fixed. Kaplan-Meier survival with the endpoint of all-cause stem revision was 94.8% (95% confidence interval: ±0.9%) at 37 years, and with the endpoint of aseptic loosening/failure of ingrowth was 98.7% (95% confidence interval: ±0.5) at 37 years. Harris hip scores improved significantly from 43 preoperatively to 76 most recently. CONCLUSION: This tapered, titanium, porous plasma spray-coated femoral component continues to demonstrate high long-term survival with a low rate of femoral component revision for any reason or aseptic loosening/failure of ingrowth.

Are Corrosion and Material Loss a Threat for Titanium-Titanium Tapers in Total Hip Arthroplasty Modular Acetabular Components?

BACKGROUND: Extensive research has reported on fretting corrosion and material loss for a variety of metal taper interfaces in orthopedic devices. For modular acetabular shell-liner constructs, the interfaces studied thus far have consisted of mixed-metal pairings, and the risk of fretting corrosion and material loss for the all-titanium (Ti) shell-liner taper junction in one ceramic-on-ceramic (COC) design remains poorly understood. We asked: do Ti shell-liner taper interfaces in COC total hip arthroplasty devices show in vivo evidence of (1) fretting and/or corrosion, and (2) quantifiable potential material loss? METHODS: We examined 22 shell-liner pairs and 22 single liners from retrieved COC components. The taper interface surfaces were assessed for fretting corrosion using a semiquantitative scoring method and imaged with scanning electron microscopy. A subcohort of components was measured with a coordinate measuring machine, and volumetric material loss and maximum wear depth were calculated. RESULTS: Fretting corrosion at the taper interfaces was minimal to mild for 95% of liners and 100% of shells. Imaging revealed fretting marks within a band of corrosion on some implants and evidence of corrosion not in the proximity of mechanical damage. Estimated material loss ranged from 0.2 to 1.3 mm3 for liners, and 0.5 to 1.1 mm3 for shells. Maximum wear depth for all components was 0.03 mm or less. CONCLUSIONS: Our results indicate that, compared to other taper junctions in total joint arthroplasty, the risk of corrosion and material loss may be minimal for Ti shell-liner interfaces.