Total Joint Arthroplasty Is a Viable Treatment Option for Patients With Osteonecrosis and Osteoarthritis After Bone Marrow Transplantation.

Background: Long-term survival in patients who receive bone marrow transplantation (BMT) is increasing. However, osteonecrosis and secondary osteoarthritis (OA) of the hip and knee are common complications in this population due to post-transplant steroid treatment to prevent graft vs host disease. The purpose of this study was to evaluate the outcomes of total joint arthroplasty (TJA) in patients with prior BMT and compare them to those of patients undergoing TJA for primary OA. Methods: Patients with a history of BMT undergoing primary TJA from 2013 to 2021 were retrospectively reviewed. Patients were matched 1:1 by surgical site, sex, age, body mass index, American Society of Anesthesiologists score, and Elixhauser Comorbidity Index to patients undergoing TJA for primary OA. Demographics, intraoperative blood loss, perioperative transfusion requirements, hospital length of stay, 90-day emergency department visits and readmissions, all-cause revisions, and 2-year mortality were compared between cohorts. Results: There were 17 patients undergoing total knee arthroplasty (TKA) after BMT (TKA-BMT) and 43 patients undergoing total hip arthroplasty (THA) after BMT (THA-BMT). More TKA-BMT and THA-BMT patients were immunosuppressed preoperatively compared to 17 matched TKA-OA and 43 THA-OA patients (P = .018 and P < .001). There were no other significant perioperative differences between BMT and OA groups. Two-year patient and implant survivorship for TKA-BMT and THA-BMT patients were high and not statistically different from TKA-OA and THA-OA cohorts. Conclusions: TJA after BMT provides satisfactory perioperative and short-term outcomes and is a viable treatment option for patients with osteonecrosis and secondary OA after BMT treatment.

Inertial Sensor Gait Analysis of Trendelenburg Gait in Patients Who Have Hip Osteoarthritis.

BACKGROUND: Gait abnormalities such as Trendelenburg gait (TG) in patients who have hip osteoarthritis (OA) have traditionally been evaluated using clinicians' visual assessment. Recent advances in portable inertial gait sensors offer more sensitive, quantitative methods for gait assessment in clinical settings. This study sought to compare sensor-derived metrics in a cohort of hip OA patients when stratified by clinical TG severity. METHODS: There were 42 patients who had hip OA and were grouped by TG severity (mild, moderate, and severe) through visual assessment by a single arthroplasty surgeon who had > 30 years of experience. After informed consent, wireless inertial sensors placed at the midpoint of the intercristal line collected gait parameters including pelvic shift, support time, toe-off symmetry, impact, and cadence. Clinical data on hip strength, range of motion, and Kellgren-Lawrence grade were collected. RESULTS: Worsening TG severity had a higher mean Kellgren-Lawrence grade (2.5 versus 3.2 versus 3.4; P = .014) and reduced passive hip abduction (P = .004). Severe TG group demonstrated predominantly contralateral pelvic shift (n = 9 of 10, 90.0%), while ipsilateral shift was more frequently detected in moderate (n = 10 of 18, 55.6%) and mild groups (n = 9 of 14, 64.3%; P = .021). Contralateral single support time bias was greatest in severe TG (35.7% versus 50.0 versus 90.0%; P = .027). Asymmetric toe-off, impact, and support times were observed in all groups. CONCLUSIONS: Traditional understanding of TG is that truncal shift occurs to the ipsilateral side. Using sensor-based measurements, the present study demonstrates a shift of the weight-bearing axis toward the contralateral side with increasing TG severity, which has not been previously described. Inertial sensors are feasible, quantitative gait measuring tools, and may reveal subtle patterns not readily discernible by traditional methods.

Gender Trends in Authorship in 6 Major Orthopaedic Journals.

BACKGROUND: Historically, orthopaedic surgery has had low female representation, with <6% of practicing surgeons identifying as female. Although prior literature has illustrated gender disparities in first and last authorship as well as changes in gender representation over time, less attention has been paid to middle authorship. We hypothesized that trends in female authorship would reflect increasing female participation in orthopaedic surgery and orthopaedic subspecialties coinciding with an overall increase in female authorship. METHODS: Bibliometric information from articles published between 2011 and 2021 in 6 orthopaedic journals was extracted with use of the Web of Science. Collected data included author order, author names, affiliation, and corresponding author address. A gender was assigned with the use of Genderize.io, which is validated software, on the basis of author first name. Statistical analysis was performed with use of an analysis of variance for each journal, and linear regression was performed to determine trends, controlling for year. RESULTS: Among all included orthopaedic journals, female middle authorship increased by 5 percentage points, female first authorship increased by 4 percentage points, and female last authorship increased by 1 percentage point. Over the study period, the highest rate of female middle authorship (28%) was seen in the Journal of Pediatric Orthopaedics, whereas the lowest rate (16%) was seen in The Journal of Arthroplasty . We found that the 5 highest-producing female last authors were, on average, cited significantly less per publication than their male counterparts in all but 2 journals. CONCLUSIONS: Gender gaps exist within orthopaedic surgery as well as within its body of literature. Although this study highlights areas of growth, it also promotes further inquiry into research productivity and the availability of opportunity within orthopaedic surgery as a whole. The increase in female middle authorship overall and in each journal demonstrates momentum for future growth for women in the field of orthopaedic surgery.

Body Mass Index and American Society of Anesthesiologists Score Predict Perioperative Delays in Different Phases for Total Hip Arthroplasty.

Perioperative efficiency has become increasingly important with cost constraints and expanding indications for total hip arthroplasty (THA). We chose to analyze body mass index (BMI) and American Society of Anesthesiologists (ASA) score, in predicting perioperative efficiency. We retrospectively reviewed the institutional database for primary THAs from July 2015 to January 2018. Patient demographics and perioperative times lines were collected. A multivariable model was utilized to evaluate BMI (< 30, ≥ 30) and ASA (< 3, ≥ 3) for all outcomes. A total of 2,934 patients were included with mean age 62.0 (12.2) years, and 1,599 (54.5%) were female. A BMI ≥ 30 was associated with prolonged operative time (p < 0.001) while an ASA ≥ 3 was predictive of post-anesthesia care unit time (p < 0.001), physical therapy hours (p < 0.001), and length of stay (p < 0.001). Both BMI (p = 0.004) and ASA (p < 0.001) were associated with skilled nursing/rehabilitation dispositions. While BMI predicts prolonged operative time, ASA predicts perioperative delays for anesthesia, nursing, and physical therapy. (Journal of Surgical Orthopaedic Advances 32(3):169-172, 2023).

Jones Fracture in the National Football League.

Background: Jones fracture, or proximal fifth metatarsal fracture, is a common injury in National Football League (NFL)-caliber athletes. Combine draft performance can greatly impact the long-term success of these athletes, and substantial emphasis has been placed on early return to play (RTP) and the minimization of post-operative complications after Jones fracture in these athletes. To date, no study has specifically described the treatment and outcomes of this injury specifically in NFL-caliber players, considering factors relevant to this unique population. Thus, the purpose of this review is to delve into Jones fracture in NFL-caliber athletes, evaluating the diagnostic, treatment, and RTP considerations. Methods: We searched Medline (PubMed), Embase (Elsevier), Scopus (Elsevier), and SPORTDiscus (EBSCOhost) for the concept of Jones fractures in the NFL. Using the PRISMA guidelines, a team of three reviewers conducted abstract screenings, full-text screenings, and the extraction of studies describing Jones fractures specifically in the NFL. Results: Of the 1911 studies identified, 6 primary retrospective studies met the inclusion and exclusion criteria. The heterogeneity of the outcome reporting precluded a meta-analysis; thus, a qualitative review of manuscripts describing Jones fracture was carried out. Classification, diagnosis, and treatment considerations, RTP statistics and outcomes, and complications were discussed. Amongst the primary studies, there were 285 Jones fractures, all athletes were able to RTP, and the average time to RTP ranged from 6 weeks to 27 weeks. For complications, with operative treatment, the refracture rate ranged from 4 to 12%, and incomplete healing ranged from 7 to 50%. RTP was 15 weeks for refractures. There were no patient-reported outcomes. Conclusions: The vast majority of Zone 2/3 Jones fractures are treated with IM screw fixation with or without adjunctive orthobiologics, such as bone marrow aspirate concentrate, in NFL-caliber athletes. The six major series investigating outcomes after the operative treatment of Jones fractures in NFL players reveal very positive findings overall with regard to RTP, reoperation, and career continuation.

Primary Total Knee Arthroplasty in Patients Aged 45 Years or Younger: 162 Total Knee Arthroplasties With a Mean Follow-up Duration of 7 Years.

Background: There are few large studies evaluating total knee arthroplasty (TKA) in young patients. Therefore, we sought to evaluate patients aged 45 years or younger undergoing a primary TKA. Methods: This was a retrospective, single-institution study, from 2003 to 2018, evaluating primary TKA in patients aged 45 years or younger. We identified 162 TKAs with a minimum follow-up duration of 2 years. Common surgical indications were degenerative joint disease (50%), post-traumatic arthritis (21%), and inflammatory arthritis (20%). Forty-nine knees had a prior significant knee surgery. We evaluated survivorship free of revision for any reason and aseptic revision. In addition, we characterized complication rates and risk factors for failure. Results: The mean age was 39 years, 70% were female, and the mean clinical follow-up duration was 7 years. At 8 years, survivorship free of revision for any reason was 82%, and survivorship free of aseptic revision was 87%. Fifty-five knees experienced at least 1 complication, with an overall complication rate of 34%. There were 6 (4%) periprosthetic joint infections (PJIs), and 24 (15%) knees of patients underwent manipulation under anesthesia with or without arthroscopic lysis of adhesions. There were no specific risk factors for revisions identified. Age less than 40 years was associated with PJI (P = .031), and marital status at the time of TKA was associated with arthrofibrosis requiring an intervention (P = .045). Conclusions: TKAs in patients aged 45 years or younger are associated with acceptable survivorship at a mean follow-up duration of 7 years. Patients should be counseled about the elevated risk of complications, specifically PJI and arthrofibrosis.

Tibiopedal Motion Following Tendo-Achilles Lengthening or Gastrocnemius Recession in Total Ankle Replacement: A Comparative Cohort Study.

BACKGROUND: End-stage ankle arthritis is a debilitating condition often necessitating total ankle replacement (TAR). Tendo-Achilles lengthening (TAL) and gastrocnemius recession (GR) are commonly performed with TAR to improve ankle dorsiflexion (DF). No studies to date have radiographically analyzed tibiopedal motion to guide surgical management. The purpose of this study is to determine the effect of a TAL or GR during TAR on radiographic tibiopedal range of motion (ROM). METHODS: A retrospective review of a prospectively maintained database was conducted followed by a propensity score-matched analysis of 110 patients who underwent TAL (n = 26), GR (n = 29), or no lengthening procedure (n = 55) with TAR. Minimum of 1-year ROM radiographic follow-up was required. Exclusion criteria included (1) calcaneal osteotomies, (2) simultaneous or previous hindfoot or midfoot arthrodesis, (3) prior ankle arthrodesis, or (4) revision TAR. Demographic data were extracted from the TAR database. Radiographic assessment included tibiopedal dorsiflexion (DF) and plantarflexion (PF). RESULTS: DF improved by 2.8 degrees (P = .0286) and by 6.0 degrees (P < .0001) in the TAL and GR cohorts, respectively, with no difference in the control group (+0.7 degrees, P = .3764). PF was decreased by 4.5 degrees (P = .0152) and by 7.2 degrees (P = .0002) in the TAL and GR cohorts, respectively, with no difference in the control group (-0.2 degrees, P = .8546). Minimal differences were observed for total arc of motion for all 3 groups (control 0.5 degrees, GR -1.2 degrees, TAL -1.7 degrees), all of which were nonsignificant (all P > .05). There was no between-group difference in the change in overall arc of motion between the groups (P = .3599). GR resulted in a greater increase in DF (6.0 vs 2.8 degrees; P = .1074), with a reciprocal greater decrease in PF (7.2 vs 4.5 degrees; P = .2416) compared with the TAL cohort. CONCLUSION: Both TAL and GR increased postoperative DF; however, this was accompanied by a reciprocal loss in PF. Minimal differences were observed for total arc of motion. Patients should be counseled that concomitant procedures performed to increase DF will do so at the expense of PF. LEVEL OF EVIDENCE: Level III, retrospective review of prospectively collected data.

Total joint arthroplasty following solid organ transplants: complications and mid-term outcomes.

PURPOSE: Survival after solid organ transplant (SOT) is improving, and demand for total joint arthroplasty (TJA) among SOT recipients is rising. Outcomes including revision, periprosthetic joint infection, and survivorship based on SOT type are variable. We sought to compare peri-operative complications, implant survivorship, and mortality for patients undergoing TJA following SOT. METHODS: A retrospective review of the institutional database for primary TJA among SOT recipients from 2000 to 2020 was performed. Revisions, conversion TJA, and patients with multiple organ transplants were excluded. Patients were stratified by transplant organ. Transfusions, 90-day readmissions and emergency department (ED) visits, revisions, and mortality were compared using descriptive statistics and Cox proportional hazard ratios. RESULTS: A total of 119 total hip arthroplasties (THA) and 63 total knee arthroplasties (TKA) in SOT recipients were studied. Most common SOT was renal (39%), then lung (27%), liver (24%), and heart (10%). TKA postoperative transfusion rates varied by organ (p = 0.037; [heart 0%, liver 9.5%, renal 24.0%, lung 50.0%]). Implant survivorship was 95.6% at one year (95% CI 90.3-98.1) and 92.1% at four years (83.9-96.3). Mortality was 2.9% at one year (95% CI 1.1-7.4) and 23.2% at four years (95% CI 16.1-32.3). After adjusting for procedure, duration from transplant to TJA, age, and Elixhauser Index, lung recipients had higher mortality versus heart (RR 4.39 [95% CI 1.64-15.38]; p = 0.002), kidney (7.98 [3.04-24.61]; p < 0.001), and liver (7.98 [3.04-24.61; p < 0.001) patients. CONCLUSION: TJA after SOT yields acceptable peri-operative outcomes and implant survivorship, but mortality risk is substantial, especially among lung transplant recipients.

Current Trends in Revision Hip Arthroplasty: Indications and Types of Components Revised.

BACKGROUND: The materials and techniques for both primary and revision total hip arthroplasty (THA) have changed over time. This study evaluated if the indications for revision THA, rates of components utilized (femoral or acetabulum, both, or head/liner exchange), length of stay (LOS), and payments to surgeons and facilities have also changed. METHODS: A retrospective study, utilizing the PearlDiver database, of 38,377 revision THA patients from January 2010 through December 2018 was performed. Data included the indication for revision, components revised (femoral or acetabulum, both, or head/liner exchange), LOS, and payments. Indications and components were analyzed by logistic regression (Dunnett's post hoc test). Revision totals were analyzed with a linear regression model. Analysis of variance assessed changes in LOS and payments. RESULTS: Patients' median age was 67 years (Q1-Q3: 59-74), and 58.7% were female. Revisions for dislocation decreased between 2010 and 2018 (odds ratio [OR] 0.82, 95% confidence interval [CI] 0.68-0.98). Revisions for component loosening increased (OR 1.54, 95% CI 1.25-1.91). Dislocation remained the most common indication (19.3%), followed by PJI (17.3%) and loosening (17.1%). Both-component (OR:1.45; 95% CI:1.25-1.67) and femoral component only revisions increased; acetabular component only and head/liner exchanges decreased. Acetabular (OR 0.57, 95% CI 0.47-0.70) and head/liner exchange (OR 0.29, 95% CI 0.20-0.43) revisions decreased, while both component exchange (OR 1.45, 95% CI 1.25-1.67) and femoral revisions (OR 1.17, 95% CI 0.99-1.37) increased. Average LOS (-0.68 days; P < .001) and surgeon payments decreased (-$261.8; P < .001) while facility payments increased ($4,211; P < .001). CONCLUSION: Indications for revision THA in this database study changed over time, with revision for dislocation decreasing and revision for loosening increasing over time. Both component and femoral revisions increased, and acetabular component and head/liner exchanges decreased. It is possible that these associations could be attributed to a number of details, the method of femoral fixation, surgical approach, and cementing, all of which require additional study.

Short-Stay Arthroplasty is Not Associated With Increased Risk of 90-Day Hospital Returns.

BACKGROUND: With the removal of total hip arthroplasty (THA) and total knee arthroplasty (TKA) from the inpatient-only list, medical centers are faced with challenging transitions to outpatient surgery. We investigated if short-stay arthroplasty, defined as length of stay (LOS) <24 hours, would influence 90-day readmissions and emergency department (ED) visits at a tertiary referral center. METHODS: The institutional database was retrospectively queried for primary TKAs and THAs from July 2015 to January 2018, resulting in 2,217 patients (1,361 TKA and 856 THA). Patient demographics, including age, gender, body mass index, and American Society of Anesthesiologists score were collected. LOS, disposition, cost of care, 90-day ED visits, and readmissions were identified through the institutional database using electronic medical record data. Univariable and multivariable models were used to evaluate rates of 90-day readmissions and ED visits based on LOS <24 hours vs ≥24 hours. RESULTS: LOS <24 h was associated with significant decreases in 90-day ED visits (P = .003) and readmissions (P = .002). After controlling for potential confounding variables with a multivariable model, a significant decrease in ED visits (P = .034) remained in the THA cohort alone. Within TKA and THA cohorts, LOS <24 h was associated with lower costs (P < .001). Eighteen percent of patients with ≥24 h LOS were discharged to skilled nursing or rehabilitation facilities. CONCLUSION: In this cohort, LOS <24 hours was associated with decreased 90-day readmissions, ED visits, and costs. With the goal of minimizing costs and maintaining patient safety while efficiently using resources, outpatient and short-stay arthroplasty are valuable, feasible options in tertiary academic centers.

Is there a problem with modular dual mobility acetabular components in revision total hip arthroplasty at mid-term follow-up?

AIMS: Modular dual mobility (MDM) acetabular components are often used with the aim of reducing the risk of dislocation in revision total hip arthroplasty (THA). There is, however, little information in the literature about its use in this context. The aim of this study, therefore, was to evaluate the outcomes in a cohort of patients in whom MDM components were used at revision THA, with a mean follow-up of more than five years. METHODS: Using the database of a single academic centre, 126 revision THAs in 117 patients using a single design of an MDM acetabular component were retrospectively reviewed. A total of 94 revision THAs in 88 patients with a mean follow-up of 5.5 years were included in the study. Survivorship was analyzed with the endpoints of dislocation, reoperation for dislocation, acetabular revision for aseptic loosening, and acetabular revision for any reason. The secondary endpoints were surgical complications and the radiological outcome. RESULTS: The overall rate of dislocation was 11%, with a six-year survival of 91%. Reoperation for dislocation was performed in seven patients (7%), with a six-year survival of 94%. The dislocations were early (at a mean of 33 days) in six patients, and late (at a mean of 4.3 years) in four patients. There were three intraprosthetic dissociations. An outer head diameter of ≥ 48 mm was associated with a lower risk of dislocation (p = 0.013). Lumbrosacral fusion was associated with increased dislocation (p = 0.004). Four revision THAs (4%) were further revised for aseptic acetabular loosening, and severe bone loss (Paprosky III) at the time of the initial revision was significantly associated with further revision for aseptic acetabular loosening (p = 0.008). Fourteen acetabular components (15%) were re-revised for infection, and a pre-revision diagnosis of reimplantation after periprosthetic joint infection (PJI) was associated with subsequent PJI (p < 0.001). Two THAs had visible metallic changes on the backside of the cobalt chromium liner. CONCLUSION: When using this MDM component in revision THA, at a mean follow-up of 5.5 years, there was a higher rate of dislocation (11%) than previously reported. The size of the outer bearing was related to the risk of dislocation. There was a low rate of aseptic acetabular loosening. Longer follow-up of this MDM component and evaluation of other designs are warranted. Cite this article: Bone Joint J 2021;103-B(7 Supple B):66-72.

Minimization of Gibbs Energy in High-Pressure Multiphase, Multicomponent Mixtures through Particle Swarm Optimization.

We present a global optimization method to construct phase boundaries in multicomponent mixtures by minimizing the Gibbs energy. The minimization method is, in essence, an extension of the Maxwell construction procedure that is used in single-component systems. For a given temperature, pressure, and overall mixture composition, it reveals the mole fractions of the thermodynamically stable phases and the composition of these phases. Our approach is based on particle swarm optimization (PSO), which is a gradient-free, stochastic method. It is not reliant on good initial guesses for the phase fractions and compositions, which is an important requirement for the high-pressure applications considered in this study because data on phase boundaries at high pressures tend to be extremely limited. One practical use of this method is to create equation-of-state tables needed by continuum-scale, multiphysics codes that are ubiquitous in high-pressure science. Currently, there does not exist a method to generate such tables that rigorously account for changes in phase boundaries due to mixing. We have done extensive testing to demonstrate that PSO can reliably determine the Gibbs energy minimum and can capture nontrivial features like eutectic and peritectic temperatures to produce coherent phase diagrams. As part of our testing, we have developed a PSO-based Helmholtz-energy minimization procedure that we have used to cross-check the results of the Gibbs energy minimization. We conclude with a critique of our approach and provide suggestions for future work, including a PSO-based entropy-maximization method that would enable the aforementioned continuum codes to perform on-the-fly, phase-equilibria calculations of multicomponent mixtures.

Mid-term results of tibial cones : reasonable survivorship but increased failure in those with significant bone loss and prior infection.

AIMS: Tibial cones are often utilized in revision total knee arthroplasty (TKA) with metaphyseal defects. Because there are few studies evaluating mid-term outcomes with a sufficient cohort, the purpose of this study was to evaluate tibial cone survival and complications in revision TKAs with tibial cones at minimum follow-up of five years. METHODS: A retrospective review was completed from September 2006 to March 2015, evaluating 67 revision TKAs (64 patients) that received one specific porous tibial cone during revision TKA. The final cohort was composed of 62 knees (59 patients) with five years of clinical follow-up or reoperation. The mean clinical follow-up of the TKAs with minimum five-year clinical follow-up was 7.6 years (5.0 to 13.3). Survivorship analysis was performed with the endpoints of tibial cone revision for aseptic loosening, tibial cone revision for any reason, and reoperation. We also evaluated periprosthetic joint infection (PJI), risk factors for failure, and performed a radiological review. RESULTS: The rate of cone revision for aseptic loosening was 6.5%, with an eight-year survival of 95%. Significant bone loss (Anderson Orthopaedic Research Institute grade 3) was associated with cone revision for aseptic loosening (p = 0.002). The rate of cone revision for any reason was 17.7%, with an eight-year survival of 84%. Sixteen percent of knees developed PJI following revision. A pre-revision diagnosis of reimplantation as part of a two-stage exchange protocol for infection was associated with both PJI (p < 0.001) and tibial cone revision (p = 0.001). CONCLUSION: Mid-term results of tibial cones showed a survivorship free of cone revision for aseptic loosening of 95%. Patients with significant bone loss were more likely to have re-revision for tibial cone failure. Infection was common, and patients receiving cones at reimplantation were more likely to develop PJI and undergo cone revision. Cite this article: Bone Joint J 2021;103-B(6 Supple A):158-164.

Varus-Valgus Constrained Implants in Revision Total Knee Arthroplasty: Mean Clinical Follow-Up of Six Years.

BACKGROUND: There is scant literature evaluating varus-valgus constrained (VVC) prostheses in contemporary revision total knee arthroplasty (TKA). Therefore, we aimed to evaluate the durability of VVC revision TKA with selective use of cones. METHODS: A retrospective review of 194 revision TKAs with VVC was performed from August 2005 through February 2018 at a single institution. The final cohort consisted of 168 TKAs with a mean follow-up of 6 years. Stems were used in all but 1 TKA, tibial cones in 48%, and femoral cones in 19%. Anderson Orthopaedic Research Institute classification in femurs was 1 in 57, 2A in 33, 2B in 62, 3 in 16, and in tibias, 1 in 42, 2A in 29, 2B in 81, and 3 in 16. RESULTS: Survival analysis showed that 93% were free of revision for aseptic component loosening, 76% were free of revision for any reason, and 74% were free of reoperation at 6 years. Anderson Orthopaedic Research Institute 3 femur or tibia, age <65 years, and progressive radiographic changes were associated with an increased risk of revision for aseptic loosening (P < .05). Progressive radiographic changes were seen in 19% of femoral and 16% of tibial constructs. The most common reason for re-revision was periprosthetic joint infection (65%). CONCLUSION: VVC revision TKA with selective use of cones provided a reasonable outcome as 93% were free of revision for aseptic loosening at 6 years. However, given the rate of patients with progressive radiographic changes and survivorship free of reoperation of 74% at 6 years, long-term follow-up will help assess the durability of these constructs.

Development of a Multiphase Beryllium Equation of State and Physics-based Variations.

We construct a family of beryllium (Be) multiphase equation of state (EOS) models that consists of a baseline ("optimal") EOS and variations on the baseline to account for physics-based uncertainties. The Be baseline EOS is constructed to reproduce a set of self-consistent data and theory including known phase boundaries, the principal Hugoniot, isobars, and isotherms from diamond-anvil cell experiments. Three phases are considered, including the known hexagonal closed-packed (hcp) phase, the liquid, and the theoretically predicted high-pressure body-centered cubic (bcc) phase. Since both the high-temperature liquid and high-pressure bcc phases lack any experimental data, we carry out ab initio density functional theory (DFT) calculations to obtain new information about the EOS properties for these two regions. At extremely high temperature conditions (>87 eV), DFT-based quantum molecular dynamics simulations are performed for multiple liquid densities using the state-of-the-art Spectral Quadrature methodology in order to validate our selected models for the ion- and electron-thermal free energies of the liquid. We have also performed DFT simulations of hcp and bcc with different exchange-correlation functionals to examine their impact on bcc compressibility, which bound the hcp-bcc transition pressure to within 4 ± 0.5 Mbar. Our baseline EOS predicts the first density maximum along the Hugoniot to be 4.4-fold in compression, while the hcp-bcc-liquid triple-point pressure is predicted to be at 2.25 Mbar. In addition to the baseline EOS, we have generated eight variations to accommodate multiple sources of potential uncertainties such as (1) the choice of free-energy models, (2) differences in theoretical treatments, (3) experimental uncertainties, and (4) lack of information. These variations are designed to provide a reasonable representation of nonstatistical uncertainties for the Be EOS and may be used to assess its sensitivity to different inertial-confinement fusion capsule designs.

Are Patients Taking Benzodiazepines at Increased Risk for Complications Following Primary Total Knee Arthroplasty?

BACKGROUND: Benzodiazepines are commonly taken by patients who are undergoing total knee arthroplasty (TKA), but there is a paucity of studies evaluating any associations. Therefore, we hoped to study if patients taking preoperative benzodiazepines would have increased complications following TKA. METHODS: Using a nationwide database, from 2010 to 2019, we evaluated patients undergoing primary TKA who either did or did not have a preoperative record of benzodiazepine prescription. We performed a multivariable logistic regression analysis, adjusting for multiple variables (age, gender, obesity, and Charlson comorbidity index), to determine the association of preoperative benzodiazepine use and adverse events in a matched cohort. Furthermore, we stratified patients by one vs multiple preoperative benzodiazepine prescription(s). We evaluated 90-day and 2-year rates of revision, resection, femur fracture fixation, manipulation under anesthesia (MUA), and delirium. RESULTS: Patients filling more than one preoperative benzodiazepine prescription had increased adjusted odds of 90-day (odds ratio [OR] = 1.198, confidence interval [CI] = 1.086-1.320) and 2-year (OR = 1.188, CI = 1.125-1.254) revision; 90-day resection (OR = 1.430, CI = 1.125-1.817); 90-day (OR = 1.639, CI = 1.255-2.141) and 2-year (OR = 1.646, CI = 1.412-1.919) femur fracture fixation; and 2-year delirium (OR = 2.288, CI = 1.564-3.382). Preoperative benzodiazepine users had decreased adjusted odds of 90-day (OR = 0.670, CI = 0.639-0.702) and 2-year (OR = 0.702, CI = 0.671-0.734) MUA. CONCLUSION: After controlling for multiple variables, benzodiazepine use was associated with increased rates of revision, resection, femur fracture fixation, and delirium. Furthermore, benzodiazepine use was also associated with a decreased rate of MUA. Orthopaedic professionals can counsel patients taking this group of medications about the associated adverse events. Future studies should assess the use of other muscle relaxants in the prevention of knee stiffness and MUA.

Body Mass Index, American Society of Anesthesiologists Score, and Elixhauser Comorbidity Index Predict Cost and Delay of Care During Total Knee Arthroplasty.

BACKGROUND: Body mass index (BMI), American Society of Anesthesiologists (ASA) score, and Elixhauser Comorbidity Index are measures that are utilized to predict perioperative outcomes, though little is known about their comparative predictive effects. We analyzed the effects of these indices on costs, operating room (OR) time, and length of stay (LOS) with the hypothesis that they would have a differential influence on each outcome variable. METHODS: A retrospective review of the institutional database was completed on primary TKA patients from 2015 to 2018. Univariable and multivariable models were constructed to evaluate the strength of BMI, ASA, and Elixhauser comorbidities for predicting changes to total hospital and surgical costs, OR time, and LOS. RESULTS: In total, 1313 patients were included. ASA score was independently predictive of all outcome variables (OR time, LOS, total hospital and surgical costs). BMI, however, was associated with intraoperative resource utilization through time and cost, but only remained predictive of OR time in an adjusted model. Total Elixhauser comorbidities were independently predictive of LOS and total hospital cost incurred outside of the operative theater, though they were not predictive of intraoperative resource consumption. CONCLUSION: Although ASA, BMI, and Elixhauser comorbidities have the potential to impact outcomes and cost, there are important differences in their predictive nature. Although BMI is independently predictive of intraoperative resource utilization, other measures like Elixhauser and ASA score were more indicative of cost outside of the OR and LOS. These data highlight the differing impact of BMI, ASA, and patient comorbidities in impacting cost and time consumption throughout perioperative care.

A Case Complexity Modifier Is Warranted for Primary Total Knee Arthroplasty.

BACKGROUND: The Center for Medicare and Medicaid Services is faced with a challenge of decreasing the cost of care for total knee arthroplasty (TKA) but must make efforts to prevent patient selection bias in the process. Currently, no appropriate modifier codes exist for primary TKA based on case complexity. We sought to determine differences in perioperative parameters for patients with complex primary TKA with the hypothesis that they would require increased cost of care, prolonged care times, and have worse postoperative outcome metrics. METHODS: We performed a single-center retrospective review from 2015 to 2018 of all primary TKAs. Patient demographics, medial proximal tibial angle (mPTA), lateral distal femoral angle (lDFA), flexion contracture, cost of care, and early postoperative outcomes were collected. Complex patients were defined as those requiring stems or augments, and multivariable logistic regression analysis and propensity score matching were performed to evaluate perioperative outcomes. RESULTS: About 1043 primary TKAs were studied, and 84 patients (8.3%) were deemed complex. For this cohort, surgery duration was greater (P < .001), cost of care higher (P < .001), and patients had a greater likelihood for 90-day hospital return. Deviation of mPTA and lDFA was significantly greater preoperatively before and after propensity score matching. Cut point analysis demonstrated that preoperative mPTA <83o or >91o, lDFA <84o or >90o, flexion contracture >10o, and body mass index >35.7 were associated with complex procedures. CONCLUSION: Complex primary TKA may be identifiable preoperatively and those cases associated with prolonged operative time, excess hospital cost of care, and increased 90-day hospital returns. This should be considered in future reimbursement models to prevent patient selection bias, and a complexity modifier is warranted.

A Specific Capsular Repair Technique Lowered Early Dislocations in Primary Total Hip Arthroplasty Through a Posterior Approach.

BACKGROUND: Dislocation is a challenging problem after total hip arthroplasty (THA). We sought to evaluate the incidence of early dislocation with 2 different posterior repair techniques after THA using a posterior approach. METHODS: From September of 2008 to August of 2019, we evaluated 841 THAs performed by a single surgeon using a posterior approach. Before November of 2015, the capsule was repaired to the greater trochanter (group 1, 605 patients). Starting November 2015, the posterior capsule was repaired in a side-to-side fashion (direct soft-tissue repair) (group 2, 236 patients). There was a mean follow-up of 31.1 months (range, 2.5-122.5 months). A multivariable logistic regression model was constructed to assess the impact of baseline patient and operative factors on the dislocation rate. RESULTS: There were 22 dislocations, all of which occurred in group 1. There were no dislocations in group 2. After adjusting for patient and operative factors, the direct soft-tissue repair had a large impact on the overall multivariable model as indicated by its effect likelihood ratio of 10.33 (P = .001); however, the odds ratio was not calculable for this factor, given that there were no dislocations in hips with direct soft-tissue repair. Increasing age was associated with an increased odds of dislocation (odds ratio, 1.04, P = .017), with an effect likelihood ratio of 6.25 (P = .012). CONCLUSIONS: Switching from a capsular repair to the greater trochanter to a side-to-side capsular repair was associated with a decreased rate of dislocation in primary THA through a posterior approach.

Staying ahead of the curve: the use of spinopelvic parameters to predict curve progression and bracing success in adolescent idiopathic scoliosis.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: To investigate radiographic sagittal and spinopelvic parameters of patients with adolescent idiopathic scoliosis (AIS) treated with bracing and assess differences among those treated successfully and unsuccessfully. AIS is a three-dimensional deformity of the spine, sharing an intricate relationship with pelvic morphology. However, the most relevant predictors of curve progression have historically been coronal parameters and skeletal maturity. Sagittal and spinopelvic parameters have not been thoroughly investigated as predictors of curve progression and brace treatment success. METHODS: Retrospective review of AIS patients who underwent brace treatment. Coronal Cobb angles (CC), pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), thoracic kyphosis (TK), lumbar lordosis (LL), and thoracic spinopelvic angles (T1SP, T9SP) were measured prior to initiation of bracing. The sagittal and spinopelvic parameters of patients requiring surgical treatment due to curve progression were compared to those treated successfully with bracing. RESULTS: No significant differences were found for age, race, gender, Risser category (0/1 vs 2/3), initial CC, TK, LL, T1SP, or T9SP between cohorts. The cohort requiring surgery had significantly lower PI (p < 0.001, 42.0 v. 54.6), SS (p < 0.001, 37.0 v. 44.5), and PT (p = 0.003, 5.0 v. 10.2) compared to those successfully treated with bracing. Multivariable models controlling for Risser stage and Initial CC revealed the odds for successful brace treatment increases with an increase in PI (OR = 1.47, CI 1.18-1.83, p < 0.001), SS (OR = 1.26, CI 1.07-1.48, p = 0.006), and PT (OR = 1.43, CI 1.09-1.86, p = 0.006) (Table 3). The odds of successful brace treatment is given per one-unit increase for each radiographic measure after adjusting for Initial CC and Risser sign which were forced into each multivariable model. CONCLUSIONS: Spinopelvic parameters may indicate potential spine adaptability and skeletal maturity. For these reasons, we proposed that spinopelvic parameters may be a potential predictor of curve progression and brace treatment success. Our results demonstrated a higher risk of curve progression with lower PI, PT, or SS which support this hypothesis, however, given the small sample size and high variability, the magnitude of this effect should be viewed with caution and should serve as an impetus to further, larger scale studies to investigate the value spinopelvic parameters in curve progression and bracing efficacy. LEVEL OF EVIDENCE: IV.