From emotional arousal to executive action. Role of the prefrontal cortex.

Emotional arousal is caused by the activity of two parallel ascending systems targeting mostly the subcortical limbic regions and the prefrontal cortex. The aversive, negative arousal system is initiated by the activity of the mesolimbic cholinergic system and the hedonic, appetitive, arousal is initiated by the activity of the mesolimbic dopaminergic system. Both ascending projections have a diffused nature and arise from the rostral, tegmental part of the brain reticular activating system. The mesolimbic cholinergic system originates in the laterodorsal tegmental nucleus and the mesolimbic dopaminergic system in the ventral tegmental area. Cholinergic and dopaminergic arousal systems have converging input to the medial prefrontal cortex. The arousal system can modulate cortical EEG with alpha rhythms, which enhance synaptic strength as shown by an increase in long-term potentiation (LTP), whereas delta frequencies are associated with decreased arousal and a decrease in synaptic strength as shown by an increase in long-term depotentiation (LTD). It is postulated that the medial prefrontal cortex is an adaptable node with decision making capability and may control the switch between positive and negative affect and is responsible for modifying or changing emotional state and its expression.

Surgical Approach Does Not Influence Instability Risk in Revision Total Hip Arthroplasty.

BACKGROUND: Although the direct anterior (DA) approach has increased in popularity for primary total hip arthroplasty (THA), there is limited evidence regarding its use for revision THA. It is unknown whether the dislocation benefit seen in the primary setting translates to revision cases. METHODS: This retrospective review compared the dislocation rates of revision THA performed through DA versus postero-lateral (PL) approaches at a single institution (2011 to 2021). Exclusion criteria included revision for instability, ≥ 2 prior revisions, approaches other than DA or PL, and placement of dual-mobility or constrained liners. There were 182 hips in 173 patients that met the inclusion criteria. The average follow-up was 6.5 years (range, 2 to 8 years). RESULTS: There was a trend toward more both-component revisions being performed through the PL approach. There were no differences in dislocation rates between the DA revision and PL revision cohorts, which were 8.1% (5 of 72) and 7.5% (9 of 120), respectively (P = .999). Dislocation trended lower when the revision approach was discordant from the primary approach compared to cases where primary and revision had a concordant approach (4.9 versus 8.5%), but this was not statistically significant (P = .740). No significant differences were found in return to operating room, 90-day emergency department visits, or 90-day readmissions. However, the length of stay was significantly shorter in patients who had DA revisions after a primary PL procedure (P = .021). CONCLUSIONS: Dislocation rates following revision THA did not differ between the DA and PL approaches irrespective of the primary approach. Surgeons should choose their revision approach based on their experience and the specific needs of the patient.

Intraoperative Surgeon-Administered Adductor Canal Block Is a Safe Alternative to Preoperative Anesthesiologist-Administered Adductor Canal Block in Primary Total Knee Arthroplasty.

BACKGROUND: The shift toward outpatient total knee arthroplasties (TKAs) has led to a demand for effective perioperative pain control methods. A surgeon-performed "low" adductor canal block ("low-ACB") technique, involving an intraoperative ACB, is gaining popularity due to its efficiency and early pain control potential. This study examined the transition from traditional preoperative anesthesiologist-performed ultrasound-guided adductor canal blocks ("high-ACB") to low-ACB, evaluating pain control, morphine consumption, first physical therapy visit gait distance, hospital length-of-stay, and complications. METHODS: There were 2,620 patients at a single institution who underwent a primary total knee arthroplasty between January 1, 2019, and December 31, 2022, and received either a low-ACB or high-ACB. Cohorts included 1,248 patients and 1,372 patients in the low-ACB and high-ACB groups, respectively. Demographics and operative times were similar. Patient characteristics and outcomes such as morphine milligram equivalents (MMEs), Visual Analog Scale pain scores, gait distance (feet), length of stay (days), and postoperative complications (30-day readmission and 30-day emergency department visit) were collected. RESULTS: The low-ACB cohort had higher pain scores over the first 24 hours (5.05 versus 4.86, P < .001) and higher MME at 6 hours (11.49 versus 8.99, P < .001), although this was not clinically significant. There was no difference in pain scores or MME at 12 or 24 hours (20.81 versus 22.07 and 44.67 versus 48.78, respectively). The low-ACB cohort showed longer gait distance at the first physical therapy visit (188.5 versus 165.1 feet, P < .001) and a shorter length of stay (0.88 versus 1.46 days, P < .01), but these were not clinically significant. There were no differences in 30-day complications. CONCLUSIONS: The low-ACB offers effective pain relief and comparable early recovery without increasing operative time or the complication rate. Low-ACB is an effective, safe, and economical alternative to high-ACB. LEVEL OF EVIDENCE: Therapeutic study, Level III (retrospective cohort study).

A prefrontal cortex alpha/delta switch controls the transition from positive to negative affective states.

Positive and negative emotional states in rats can be studied by investigating ultrasonic vocalizations (USVs). Positive affect in rats is indexed by 50 kHz hedonic USVs, and negative affect is indexed by 22 kHz aversive calls. We examined the relationship of emotional states in rats using medial prefrontal cortex (MPFC) quantitative electroencephalograms (qEEG) and found that hedonic USVs were associated with active wake qEEG (high alpha/low delta power), and aversive USVs occurred with groggy wake qEEG (low alpha/high delta). Further, alpha frequency electrical stimulation of the MPFC induces hedonic calls and reward-seeking behavior, whereas delta frequency stimulation produces aversive calls and avoidance behavior. The brain region responsible for generating motor output for USVs, the periaqueductal gray (PAG), shows a motor-evoked potential that is temporally locked to the alpha (hedonic) and delta (aversive) motor-evoked potential. Closed-loop alpha frequency electrical stimulation could prevent delta qEEG and aversive USVs. At the neuronal circuit level, the alpha rhythm was associated with synaptic long-term potentiation (LTP) in the cortex, whereas the delta rhythm was associated with synaptic depotentiation (LTD) in the cortex. At the pharmacological level, NMDAR and growth factor modulation regulated these forms of neuroplasticity. At the single neuron level, excitatory neurons show increased activity in response to alpha frequencies and decreased activity during delta frequencies. In humans, the feeling of joy increased alpha and decreased delta power in frontal scalp qEEG, and the opposite response was seen for sadness. Thus, the synchronization of alpha/delta oscillations through the neuronal circuit responsible for emotional expression coordinates emotional behavior, and the switch between active wake/positive affect and groggy wake/negative affect is under the control of an LTP- LTD synaptic plasticity mechanism.

Cemented Femoral Stem Fixation: Back to the Future.

BACKGROUND: Periprosthetic fractures following elective and nonelective hip arthroplasty remain one of the most common modes of early failure. METHODS: This symposium will explore the current role of cemented fixation and periprosthetic fracture, focusing on history and rationale for cemented stem fixation, registry data, and other potential advantages of cemented stem fixation. A meticulous and methodical surgical technique of cemented stem fixation is paramount to the success and will be thoroughly discussed. RESULTS: The role of stem fixation, and its effect on periprosthetic fracture is well-documented in the literature. Yet despite this, the utilization of cemented stem fixation remains low in the United States. This paradox is multifactorial. CONCLUSION: In addition to a notable reduction in the risk of periprosthetic femur fractures, cemented stem fixation has numerous other advantages and is reproducible with a methodical surgical technique.

A Reduction in Body Mass Index From ≥ 40 to < 40 Lowers Emergency Department Visits, but May Increase All-Cause Readmissions After Primary Total Hip Arthroplasty: Conflicting 90-Day Outcomes at a Single Institution.

BACKGROUND: The American Association of Hip and Knee Surgeons tasked a 2013 workgroup to provide obesity-related recommendations in total joint arthroplasty. Morbidly obese patients (body mass index (BMI) ≥ 40) seeking hip arthroplasty were determined to be at increased perioperative risk, and surgeons were recommended to encourage these patients to reduce their BMI <40 presurgery. We report the effect of instituting a 2014 BMI <40 threshold on our primary total hip arthroplasties (THAs). METHODS: We queried our institutional database to select all primary THAs from January 2010 to May 2020. There were 1,383 THAs that were pre-2014 and 3,273 THAs that were post-2014. The 90-day emergency department (ED) visits, readmissions, and returns to operating room (OR) were identified. Patients were propensity score weight-matched according to comorbidities, age, initial surgical consultation (consult) BMI, and sex. We conducted 3 comparisons: A) pre-2014 patients who had a consult and surgical BMI ≥40 against post-2014 patients who had a consult BMI ≥40 and surgical BMI <40; B) pre-2014 patients against post-2014 patients who had a consult and surgical BMI <40; and C) post-2014 patients who had a consult BMI ≥40 and surgical BMI <40 against post-2014 patients who had a consult BMI ≥40 and surgical BMI ≥40. RESULTS: Post-2014 patients who had a consult BMI ≥ 40 and surgical BMI <40 had less ED visits (7.6 versus 14.1%, P = .0007), but similar readmissions (11.9 versus 6.3%, P = .22) and returns to OR (5.4 versus 1.6%, P = .09) compared to pre-2014 patients who had a consult BMI and surgical BMI ≥ 40. Post-2014 BMI <40 had less readmissions (5.9 versus 9.3%, P < .0001), and similar all-cause returns to OR and ED visits than patients pre-2014. Post-2014 patients who had a consult and surgical BMI ≥ 40 had lower readmissions (12.5 versus 12.8%, P = .05), and similar ED visits and returns to OR than consult BMI ≥ 40 and surgical BMI <40. CONCLUSION: Patient optimization prior to total joint arthroplasty is critical. However, the BMI optimization that mitigates risk in primary total knee arthroplasty may not apply to primary THA. We observed a paradoxical increased readmission rate for patients who reduced their BMI before THA. LEVEL OF EVIDENCE: III.

An Increase in Same-day Discharge After Total Joint Arthroplasty During the COVID-19 Pandemic Does Not Influence Patient Outcomes: A Retrospective Cohort Analysis.

Background: The coronavirus disease 2019 (COVID-19) pandemic caused major transitions in total joint arthroplasty (TJA), notably with the increased utilization of same-day discharge (SDD) pathways. This study assessed the effect of accelerated discharge pathways following the resumption of elective cases during the COVID-19 pandemic on SDD rates, adverse events, and characteristics associated with successful SDD following total hip and total knee arthroplasty. Methods: This retrospective study split patients into cohorts: TJA prior to COVID-19 (pre-COVID, July 2019-December 2019) and TJA following the resumption of elective surgeries (post-COVID, July 2020-December 2020). Patient characteristics such as age, sex, body mass index, American Society of Anesthesiologists score, and pertinent comorbidities were analyzed, and length of stay, 30-day emergency department (ED) visit rates, readmissions, and reoperations were compared. Results: A total of 1333 patients met inclusion criteria that were divided into pre-COVID (692) and post-COVID (641) cohorts. The pre-COVID group had a median age of 69 years (interquartile range 63-76), and the post-COVID group had a median age of 68 years (interquartile range 61-75) (P = .024). SDD increased from 0.1% to 28.9% (P < .001), and length of stay decreased from 1.3 days to 0.89 days (P < .001). There was no change in 30-day ED visits, readmissions, or reoperations (P = .817, P = .470, and P = .643, respectively). There was no difference in ED visits, readmissions, or reoperations in SDD patients. The odds of SDD were associated with age (P < .001, odds ratio [OR] = 0.94), body mass index (P = .006, OR = 0.95), male sex (P < .001, OR = 1.83), and history of tobacco use (P < .001, OR = 1.87). Conclusions: At our institution, the COVID-19 pandemic accelerated the utilization of SDD pathways without increasing ED visits, readmissions, or reoperations.

Institutional Adherence to the American Association of Hip and Knee Surgeons Body Mass Index Guidelines Lowers Perioperative Emergency Department Visits in Primary Total Knee Arthroplasty.

BACKGROUND: In 2013, the American Association of Hip and Knee Surgeons tasked a workgroup to provide obesity-related recommendations in total joint arthroplasty and determined that patients who had body mass index (BMI) ≥ 40 seeking hip/knee arthroplasty were at increased perioperative risk and recommended preoperative weight reduction. Few studies have shown the actual results of instituting this; therefore, we reported the effect of instituting a BMI < 40 threshold in 2014 on our elective, primary total knee arthroplasties (TKAs). METHODS: We queried an institutional database to select all TKAs conducted from January 2010 to May 2020. There were 2,514 TKA pre-2014 and 5,545 TKA post-2014 that were identified. The 90-day emergency department (ED) visits, readmissions, and returns-to-operating room (OR) outcomes were identified. Patients were propensity score weight-matched as per comorbidities, age, initial surgical consultation (consult) BMI, and sex. We conducted 3 outcome comparisons: (1) pre-2014 patients who had a consult and surgical BMI ≥ 40 against post-2014 patients who had a consult BMI ≥ 40 and surgical BMI < 40; (2) pre-2014 patients against post-2014 patients who had a consult and surgical BMI < 40; (3) post-2014 patients who had a consult BMI ≥ 40 and surgical BMI < 40 against post-2014 patients who had a consult BMI ≥ 40 and surgical BMI ≥ 40. RESULTS: Pre-2014 patients who had a consult and surgical BMI ≥ 40 had more ED visits (12.5% versus 6%, P = .002) but similar readmissions and returns-to-OR than post-2014 patients who had a consult BMI ≥ 40 and surgical BMI < 40. Pre-2014 patients who had a consult and surgical BMI < 40 had more readmissions (8.8% versus 6%, P < .0001) but similar ED visits and returns-to-OR when compared to their post-2014 counterparts. Post-2014 patients who had a consult BMI ≥ 40 and surgical BMI < 40 had fewer ED visits (5.8% versus 10.6%) but similar readmissions and returns-to-OR than patients who had a consult BMI ≥ 40 and surgical BMI ≥ 40. DISCUSSION: Patient optimization prior to total joint arthroplasty is essential. Enacting BMI reduction pathways prior to total knee arthroplasty seems to afford morbidly obese patients major risk mitigation. We must continue to ethically balance the pathology, expected improvement after surgery, and the overall risks of complications for each patient. LEVEL OF EVIDENCE: III.

The Role of Dual-Mobility Components in Total Hip Arthroplasty.

➤: Dual mobility (DM) refers to a now widely available option for total hip articulation. DM implants feature a small inner head, a hard bearing, that connects via a taper fit onto the femoral trunnion. This head freely rotates but is encased inside a larger, outer polyethylene head that articulates with a smooth acetabular component. ➤: DM acetabular components are available in the form of a monoblock shell or as a liner that is impacted into a modular shell, providing a metal articulation for the polyethylene outer head. ➤: DM is designed to increase hip stability by providing the arthroplasty construct with a higher jump distance, head-to-neck ratio, and range of motion prior to impingement. ➤: The use of DM in total hip arthroplasty continues to increase in the United States for both primary and revision arthroplasty. Surgeons should be aware of the potential benefits and pitfalls. ➤: Long-term data are lacking, especially for modular DM implants. Points of concern include a potential for accelerated polyethylene wear, intraprosthetic dislocation, and modular backside fretting corrosion.

An IGFBP2-derived peptide promotes neuroplasticity and rescues deficits in a mouse model of Phelan-McDermid syndrome.

We developed an IGFBP2-mimetic peptide fragment, JB2, and showed that it promotes basal synaptic structural and functional plasticity in cultured neurons and mice. We demonstrate that JB2 directly binds to dendrites and synapses, and its biological activity involves NMDA receptor activation, gene transcription and translation, and IGF2 receptors. It is not IGF1 receptor-dependent. In neurons, JB2 induced extensive remodeling of the membrane phosphoproteome. Synapse and cytoskeletal regulation, autism spectrum disorder (ASD) risk factors, and a Shank3-associated protein network were significantly enriched among phosphorylated and dephosphorylated proteins. Haploinsufficiency of the SHANK3 gene on chromosome 22q13.3 often causes Phelan-McDermid Syndrome (PMS), a genetically defined form of autism with profound deficits in motor behavior, sensory processing, language, and cognitive function. We identified multiple disease-relevant phenotypes in a Shank3 heterozygous mouse and showed that JB2 rescued deficits in synaptic function and plasticity, learning and memory, ultrasonic vocalizations, and motor function; it also normalized neuronal excitability and seizure susceptibility. Notably, JB2 rescued deficits in the auditory evoked response latency, alpha peak frequency, and steady-state electroencephalography response, measures with direct translational value to human subjects. These data demonstrate that JB2 is a potent modulator of neuroplasticity with therapeutic potential for the treatment of PMS and ASD.

Effect of Tibial Slope on Coronal Alignment in Total Knee Arthroplasty.

Malalignment of total knee arthroplasty (TKA) components affects function and survivorship. Common practice is to set coronal alignment prior to adjusting slope. With improper jig placement, adjustment of the slope may alter coronal alignment. The purpose of this study was to quantify the change in coronal alignment with increasing posterior tibial slope while comparing two methods of jig fixation. A prospective consecutive series of 100 patients underwent TKA using computer navigation. Fifty patients had the extramedullary cutting jig secured proximally with one pin and 50 patients had the jig secured proximally with two pins. Coronal alignment (CA) was recorded with each increasing degree of posterior slope (PS) from 0 to 7 degrees. Mean CA and change in CA were compared between cohorts. Utilizing one pin, osteotomies drifted into varus with an average change in CA of 0.34 degrees per degree PS. At 4 degrees PS, patients started to have >3 degrees of varus with 12.0% having >3 degrees of varus at 7 degrees PS. Utilizing two pins, osteotomies drifted into valgus with an average change of 0.04 degrees in CA per degree PS. No patients in the two-pin cohort fell outside 3 degrees varus/valgus CA. CA was significantly different at all degrees of PS between the cohorts. Changes in PS influenced CA making verification of tibial cut intraoperative critical. Use of >1 pin and computer navigation were beneficial to prevent coronal plane malalignment. This relationship may explain why computer navigation has been shown to improve alignment as well as survivorship and outcomes in some patients, especially those <65 years.

Adult Reconstruction Fellowship: What is Important to the Applicants?

Background: Orthopaedic surgery trainees who aim to specialize in total joint arthroplasty commonly complete an additional year of fellowship training. Limited information regarding individual programs is readily available to potential applicants. The purpose of this study is to determine what information applicants value when considering an adult reconstruction fellowship program. Methods: An anonymous survey was distributed to all 470 junior members of AAHKS. The 12-question survey gathered demographic information as well as average weighted scores (1-10) of various components regarding fellowship education, recruitment, and experiences. Subgroup analysis was performed on survey responses based on the following 3 different categories: Gender, year of training, and geographical location. Results: A total of 135 respondents completed the survey (135 of 470, 28.7% response rate). Sixty-two (45.9%) participants held the position of postgraduate year 5, 43 (31.9%) participants held the position of postgraduate year 4. Exposure to operative techniques in revision surgery (9.62), exposure to operative techniques in primary surgery (9.51), and ability to obtain desired job opportunity after fellowship (8.89) were the 3 most considered components. Higher level trainees valued information regarding average number of hours worked relative to junior trainees (P = .046). Geographic differences were noted in the following 3 variables: the number of cases performed (P = .010), whether fellows had a dedicated clinic and/or operating room (P = .002), and the average number of hours worked (P = .020). Conclusions: Amongst the 3 domains studied, applicants most valued educational components, such as exposure to various techniques surrounding total joint arthroplasty. There is a need for a centralized, comprehensive database that contains information applicants value most and this database should be customizable toward training level and location.

Zelquistinel Is an Orally Bioavailable Novel NMDA Receptor Allosteric Modulator That Exhibits Rapid and Sustained Antidepressant-Like Effects.

BACKGROUND: The role of glutamatergic receptors in major depressive disorder continues to be of great interest for therapeutic development. Recent studies suggest that both negative and positive modulation of N-methyl-D-aspartate receptors (NMDAR) can produce rapid antidepressant effects. Here we report that zelquistinel, a novel NMDAR allosteric modulator, exhibits high oral bioavailability and dose-proportional exposures in plasma and the central nervous system and produces rapid and sustained antidepressant-like effects in rodents by enhancing activity-dependent, long-term synaptic plasticity. METHODS: NMDAR-mediated functional activity was measured in cultured rat brain cortical neurons (calcium imaging), hNR2A or B subtype-expressing HEK cells, and synaptic plasticity in rat hippocampal and medial prefrontal cortex slices in vitro. Pharmacokinetics were evaluated in rats following oral administration. Antidepressant-like effects were assessed in the rat forced swim test and the chronic social deficit mouse model. Target engagement and the safety/tolerability profile was assessed using phencyclidine-induced hyperlocomotion and rotarod rodent models. RESULTS: Following a single oral dose, zelquistinel (0.1-100 µg/kg) produced rapid and sustained antidepressant-like effects in the rodent depression models. Brain/ cerebrospinal fluid concentrations associated with zelquistinel antidepressant-like activity also increased NMDAR function and rapidly and persistently enhanced activity-dependent synaptic plasticity (long-term potentiation), suggesting that zelquistinel produces antidepressant-like effects by enhancing NMDAR function and synaptic plasticity. Furthermore, Zelquistinel inhibited phencyclidine (an NMDAR antagonist)-induced hyperlocomotion and did not impact rotarod performance. CONCLUSIONS: Zelquistinel produces rapid and sustained antidepressant effects by positively modulating the NMDARs, thereby enhancing long-term potentiation of synaptic transmission.

Clinical Outcomes and Survivorship of Hybrid Total Hip Arthroplasty Performed Through the Anterior Approach.

INTRODUCTION: There is growing evidence that cemented femoral stems have lower complication rates in the elderly due to lower rates of periprosthetic fracture. The main objective of this study was to analyze the survival rate of a hybrid total hip arthroplasty (THA) construct utilizing a taper-slip femoral stem implanted through the anterior approach (AA). Secondary outcome measures were the complication rate, the rate of aseptic loosening, coronal plane alignment of the stem, and the grade of the cement mantle. METHODS: Patients who underwent AA hybrid THA from 2013 to 2020 were included. Indications for a cemented stem were age over 70 or patients with poor bone quality. Descriptive statistics were calculated for patient characteristics. Serial radiographs were reviewed for component alignment and for evidence of implant loosening. The survival of the femoral stem was recorded, with failure defined as femoral stem revision for any reason or radiographic evidence of implant loosening. RESULTS: A total of 473 hybrid THA in 426 patients were identified, with a mean age of 76 years. Mean follow-up was 38 months. Femoral stem survival was 99.2%. There were no cases of aseptic loosening of the femoral component. Mean coronal stem alignment was 0.2 degrees varus, and all were within 5 degrees of neutral. Cement mantle grade was either A or B in 94% of cases. CONCLUSION: AA hybrid THA is an excellent option in elderly patients, or patients with poor bone quality, with a femoral stem survival rate of 99.2% and a 0% rate of aseptic loosening.

Acetabular defect management and revision arthroplasty via the direct anterior approach.

OBJECTIVE: Acetabular revision arthroplasty and osseous defect management through the direct anterior approach (DAA) with or without proximal extension. INDICATIONS: Aseptic or septic component loosening, periacetabular osseous defects, pelvic discontinuity, intrapelvic cup protrusion, anterior pseudotumors, iliopsoas tendonitis, polyethylene wear or iliopsoas abscess. CONTRAINDICATIONS: Clinically relevant gluteal tendon lesions, active infection, morbid obesity, large abdominal pannus, ASA (American Society of Anesthesiologists) score > III, inguinal skin infection. SURGICAL TECHNIQUE: Electrocautery dissection is recommended to dissect the Hueter interval and to debulk pericapsular scar tissue. At all times during capsular debulking, it should be made sure not to damage the iliopsoas tendon or the neurovascular bundle. A stepwise releasing sequence can facilitate dislocation of the prosthesis. Most cases can be revised via the standard DAA but certain circumstances require an intra- or extrapelvic extension. Access to the anterior gluteal surface of the ilium can be provided using a "tensor snip". More posterior access is provided by the extensile extrapelvic approach described by Smith-Petersen. The intrapelvic Levine extension offers access to the entire visceral surface of the ilium and large parts of the anterior column. POSTOPERATIVE MANAGEMENT: Patient revised via the intra- or extrapelvic extension and patients suffering from extensive soft tissue or osseous defects should undergo postoperative weight-bearing restrictions with 20 kg for 6 weeks. RESULTS: Based on our studies, there is no limitation on the type of acetabular implant that can be used in DAA revision arthroplasty. Moreover, virtually all types of periacetabular osseous defects can be managed through the approach and its extensions. Acetabular revision arthroplasty via the DAA and its extensions is safe and can result in good midterm results.

The Off-Table Technique Increases Operating Room Efficiency in Direct Anterior Hip Replacement.

Background: When performing a total hip arthroplasty via the direct anterior approach (DAA), many orthopedic surgeons utilize an orthopedic traction table. This technique requires an expensive table, time for positioning, staff to operate the table, and time-consuming transitions when preparing the femur. Some surgeons advocate for an "off-table" technique to avoid these difficulties. In this paper, we compare operating room efficiency between on-table and off-table techniques. Material and methods: We retrospectively reviewed patients undergoing total hip arthroplasty by a single surgeon across the transition from on-table to off-table DAA technique. Three cohorts were defined; the last 40 on-table hips, the first 40 off-table hips, followed by the second 40 hips. Timestamps from the operative record were recorded to calculate setup, surgical, takedown, and total room time. Implant fixation, patient demographic data, comorbidities, and complications were recorded. Results: From cohort 1 to 2, there was a 7-minute (14.44%, P = .0002) improvement in setup time but no change in total room time. From cohort 2 to 3, there was an additional 7-minute (15.47%, P < .0001) improvement in setup time, 32-minute (25.88%, P < .0001) improvement in surgical time, and 40-minute (21.96%, P < .0001) improvement in total room time yielding cumulative changes from cohort 1 to 3 of 15 minutes (27.68%, P < .0001), 28 minutes (23.11%, P < .0001), and 43 minutes (23.37%, P < .0001), respectively. There was no correlation between height, weight, or body mass index and time at any interval. Conclusion: Conversion to an off-table DAA technique offers an improvement in operating room efficiency. This is seen in setup, operative, and total room time. Implementation could allow for an additional case each day.

Extracellular application of the N-methyl-D-aspartate receptor allosteric modulator rapastinel acts remotely to regulate Ca2+ inactivation at an intracellular locus.

BACKGROUND: A novel N-methyl-D-aspartate receptor (NMDAR) allosteric modulator, rapastinel (RAP, formerly GLYX-13), elicits long-lasting antidepressant-like effects by enhancing long-term potentiation (LTP) of synaptic transmission. RAP elicits these effects by binding to a unique site in the extracellular region of the NMDAR complex, transiently enhancing NMDAR-gated current in pyramidal neurons of both hippocampus and medial prefrontal cortex. METHODS: We compared efficacy of RAP in modulating Schaffer collateral-evoked NMDAR-currents as a function of kinetics of the Ca2+ chelator in the intracellular solution, using whole-cell patch-clamp recordings. The intracellular solution contained either the slow Ca2+ chelator EGTA [3,12-bis(carboxymethyl)-6,9-dioxa-3,12-diazatetradecane-1,14-dioic acid, 0.5 mmol/l] or the 40-500-fold kinetically faster, more selective Ca2+ chelator BAPTA {2,2',2″,2‴-[ethane-1,2-diylbis(oxy-2,1-phenylenenitrilo)] tetraacetic acid, 5 mmol/l}. NMDAR-gated currents were pharmacologically isolated by bath application of the 2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl)propanoic acid receptor antagonist 6-nitro-2,3-dioxo-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7-sulfonamide (10 µmol/l) plus the GABA receptor blocker bicuculline (20 µmol/l). RESULTS: When the slow Ca2+ chelator EGTA was in the intracellular solution, RAP elicited significant enhancement of NMDAR-gated current at a 1 µmol/l concentration, and significantly reduced current at 10 µmol/l. In contrast, when recording with the 40-500-fold kinetically faster, more selective Ca2+ chelator BAPTA, NMDAR current increased in magnitude by 84% as BAPTA washed into the cell, and the enhancement of NMDAR current by 1 µmol/l RAP was completely blocked. Interestingly, the reduction in NMDAR current from 10 µmol/l RAP was not affected by the presence of BAPTA in the recording pipette, indicating that this effect is mediated by a different mechanism. CONCLUSION: Extracellular binding of RAP to the NMDAR produces a novel, long-range reduction in affinity of the Ca2+ inactivation site on the NMDAR C-terminus accessible to the intracellular space. This action underlies enhancement in NMDAR-gated conductance elicited by RAP.

Proximal femoral replacement using the direct anterior approach to the hip.

OBJECTIVE: Proximal femoral replacement (PFR) is a salvage procedure originally developed for reconstruction after resection of sarcomas and metastatic cancer. These techniques can also be adapted for the treatment of non-oncologic reconstruction for cases involving massive proximal bone loss. The direct anterior approach (DAA) is readily utilized for revision total hip arthroplasty (THA), but there have been few reports of its use for proximal femoral replacement. INDICATIONS: Aseptic, septic femoral implant loosening, periprosthetic femoral fracture, oncologic lesions of the proximal femur. The most common indication for non-oncologic proximal femoral placement is a severe femoral defect Paprosky IIIB or IV. CONTRAINDICATIONS: Infection. SURGICAL TECHNIQUE: In contrast to conventional DAA approaches and extensions, we recommend starting the approach 3 cm lateral to the anterior superior iliac spine and performing a straight incision directed towards the fibular head. After identification and incision of the tensor fasciae lata proximally and the lateral mobilization of the iliotibial tract distally, the vastus lateralis muscle can be retracted medially as far as needed. Special care should be taken to avoid injuries to the branches of the femoral nerve innervating the vastus lateralis muscle. If required, the distal extension of the DAA can continue all the way to the knee to allow implantation of a total femoral replacement. The level of the femoral resection is detected with an x­ray. In accordance with preoperative planning, the proximal femur is resected. Ream and broach the distal femoral fragment to the femoral canal. With trial implants in place, leg length, anteversion of the implant and hip stability are evaluated. It is crucial to provide robust reattachment of the abductor muscles to the PFR prosthesis. Mesh reinforcement can be used to reinforce the muscular attachment if necessary. POSTOPERATIVE MANAGEMENT: We typically use no hip precautions other than to limit combined external rotation and extension for 6 weeks. In most cases, full weight bearing is possible after surgery. RESULTS: A PFR was performed in 16 patients (mean age: 55.1 years; range 17-84 years) using an extension of the DAA. The indication was primary bone sarcoma in 7 patients, metastatic lesion in 6 patients and massive periprosthetic femoral bone loss in 3 patients. Complications related to the surgery occurred in 2 patients (both were dislocation). Overall, 1 patient required reoperation and 1 patient died because of his disease. Mean follow-up was 34.5 months.

Femoral revision with the direct anterior approach.

OBJECTIVE: The advantages of the direct anterior approach (DAA) in primary total hip arthroplasty as a minimally invasive, muscle-sparing, internervous approach are reported by many authors. Therefore, the DAA has become increasingly popular for primary total hip arthroplasty (THA) in recent years, and the number of surgeons using the DAA is steadily increasing. Thus, the question arises whether femoral revisions are possible through the same interval. INDICATIONS: Aseptic, septic femoral implant loosening, malalignment, periprosthetic joint infection or periprosthetic femoral fracture. CONTRAINDICATIONS: A draining sinus from another approach. SURGICAL TECHNIQUE: The incision for the primary DAA can be extended distally and proximally. If necessary, two releases can be performed to allow better exposure of the proximal femur. The DAA interval can be extended to the level of the anterior superior iliac spine (ASIS) in order to perform a tensor release. If needed, a release of the external rotators can be performed in addition. If a component cannot be explanted endofemorally, and a Wagner transfemoral osteotomy or an extended trochanteric osteotomy has to be performed, the skin incision needs to be extended distally to maintain access to the femoral diaphysis. POSTOPERATIVE MANAGEMENT: Depending on the indication for the femoral revision, ranging from partial weight bearing in cases of periprosthetic fractures to full weight bearing in cases of aseptic loosening. RESULTS: In all, 50 femoral revisions with a mean age of 65.7 years and a mean follow-up of 2.1 years were investigated. The femoral revision was endofemoral in 41 cases, while a transfemoral approach with a lazy­S extension was performed in 9 patients. The overall complication rate was 12% (6 complications); 3 patients or 6% of the included patients required reoperations. None of the implanted stems showed a varus or valgus position. There were no cases of mechanical loosening, stem fracture or subsidence. Median WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) score before surgery improved significantly from preoperative (52.5) to postoperative (27.2).

Revisiting Cemented Femoral Fixation in Hip Arthroplasty.

➤: The primary means of femoral fixation in North America is cementless, and its use is increasing worldwide, despite registry data and recent studies showing a higher risk of periprosthetic fracture and early revision in elderly patients managed with such fixation than in those who have cemented femoral fixation. ➤: Cemented femoral stems have excellent long-term outcomes and a continued role, particularly in elderly patients. ➤: Contrary to historical concerns, recent studies have not shown an increased risk of death with cemented femoral fixation. ➤: The choice of femoral fixation method should be determined by the patient's age, comorbidities, and bone quality. ➤: We recommend considering cemented femoral fixation in patients who are >70 years old (particularly women), in those with Dorr type-C bone or a history of osteoporosis or fragility fractures, or when intraoperative broach stability cannot be obtained.