High-density lipoprotein mediates anti-inflammatory reprogramming of macrophages via the transcriptional regulator ATF3.

High-density lipoprotein (HDL) mediates reverse cholesterol transport and is known to be protective against atherosclerosis. In addition, HDL has potent anti-inflammatory properties that may be critical for protection against other inflammatory diseases. The molecular mechanisms of how HDL can modulate inflammation, particularly in immune cells such as macrophages, remain poorly understood. Here we identify the transcriptional regulator ATF3, as an HDL-inducible target gene in macrophages that downregulates the expression of Toll-like receptor (TLR)-induced proinflammatory cytokines. The protective effects of HDL against TLR-induced inflammation were fully dependent on ATF3 in vitro and in vivo. Our findings may explain the broad anti-inflammatory and metabolic actions of HDL and provide the basis for predicting the success of new HDL-based therapies.

Extended Prophylactic Antibiotics for Primary and Aseptic Revision Total Joint Arthroplasty: A Meta-Analysis.

BACKGROUND: There is growing interest in extended antibiotic prophylaxis (EAP) following total joint arthroplasty (TJA); however, the benefit of EAP remains controversial. For this investigation, both oral and intravenous antibiotic protocols were included in the EAP group. METHODS: The Cochrane Database of Systematic Reviews, Cochrane Register of Controlled Trials, PubMed, MEDLINE, Web of Science, Ovid Embase, Elton B. Stephens CO, and Cumulative Index to Nursing and Allied Health Literature were queried for literature comparing outcomes of primary and aseptic revision total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients who were treated with either ≤24 hours of postoperative antibiotic prophylaxis (standard of care [SoC]) or >24 hours of EAP. The primary outcome was periprosthetic joint infection (PJI). A pooled relative-risk random-effects Mantel-Haenszel model was implemented to compare cohorts. RESULTS: There were 18 studies with a total of 19,153 patients included. There was considerable variation in antibiotic prophylaxis protocols with first-generation cephalosporins being the most commonly implemented antibiotic for both groups. Patients treated with EAP were 35% less likely to develop PJI relative to the SoC (P = .0004). When examining primary TJA, patients treated with EAP were 39% and 40% less likely to develop a PJI for TJA (P = .0008) and THA (P = .02), respectively. There was no significant difference for primary TKA (P = .17). When examining aseptic revision TJA, EAP led to a 36% and 47% reduction in the probability of a PJI for aseptic revision TJA (P = .007) and aseptic revision TKA (P = .008), respectively; there was no observed benefit for aseptic revision THA (P = .36). CONCLUSIONS: This meta-analysis demonstrated that patients treated with EAP were less likely to develop a PJI relative to those treated with the SoC for all TJA, primary TJA, primary THA, aseptic revision TJA, and aseptic revision TKA. There was no significant difference observed between EAP and SoC for primary TKA or aseptic revision THA.

Chat Generative Pretrained Transformer (ChatGPT) and Bard: Artificial Intelligence Does not yet Provide Clinically Supported Answers for Hip and Knee Osteoarthritis.

BACKGROUND: Advancements in artificial intelligence (AI) have led to the creation of large language models (LLMs), such as Chat Generative Pretrained Transformer (ChatGPT) and Bard, that analyze online resources to synthesize responses to user queries. Despite their popularity, the accuracy of LLM responses to medical questions remains unknown. This study aimed to compare the responses of ChatGPT and Bard regarding treatments for hip and knee osteoarthritis with the American Academy of Orthopaedic Surgeons (AAOS) Evidence-Based Clinical Practice Guidelines (CPGs) recommendations. METHODS: Both ChatGPT (Open AI) and Bard (Google) were queried regarding 20 treatments (10 for hip and 10 for knee osteoarthritis) from the AAOS CPGs. Responses were classified by 2 reviewers as being in "Concordance," "Discordance," or "No Concordance" with AAOS CPGs. A Cohen's Kappa coefficient was used to assess inter-rater reliability, and Chi-squared analyses were used to compare responses between LLMs. RESULTS: Overall, ChatGPT and Bard provided responses that were concordant with the AAOS CPGs for 16 (80%) and 12 (60%) treatments, respectively. Notably, ChatGPT and Bard encouraged the use of non-recommended treatments in 30% and 60% of queries, respectively. There were no differences in performance when evaluating by joint or by recommended versus non-recommended treatments. Studies were referenced in 6 (30%) of the Bard responses and none (0%) of the ChatGPT responses. Of the 6 Bard responses, studies could only be identified for 1 (16.7%). Of the remaining, 2 (33.3%) responses cited studies in journals that did not exist, 2 (33.3%) cited studies that could not be found with the information given, and 1 (16.7%) provided links to unrelated studies. CONCLUSIONS: Both ChatGPT and Bard do not consistently provide responses that align with the AAOS CPGs. Consequently, physicians and patients should temper expectations on the guidance AI platforms can currently provide.

Fatal Cytomegalovirus Infection in an Adult with Inherited NOS2 Deficiency.

BACKGROUND: Cytomegalovirus (CMV) can cause severe disease in children and adults with a variety of inherited or acquired T-cell immunodeficiencies, who are prone to multiple infections. It can also rarely cause disease in otherwise healthy persons. The pathogenesis of idiopathic CMV disease is unknown. Inbred mice that lack the gene encoding nitric oxide synthase 2 (Nos2) are susceptible to the related murine CMV infection. METHODS: We studied a previously healthy 51-year-old man from Iran who after acute CMV infection had an onset of progressive CMV disease that led to his death 29 months later. We hypothesized that the patient may have had a novel type of inborn error of immunity. Thus, we performed whole-exome sequencing and tested candidate mutant alleles experimentally. RESULTS: We found a homozygous frameshift mutation in NOS2 encoding a truncated NOS2 protein that did not produce nitric oxide, which determined that the patient had autosomal recessive NOS2 deficiency. Moreover, all NOS2 variants that we found in homozygosity in public databases encoded functional proteins, as did all other variants with an allele frequency greater than 0.001. CONCLUSIONS: These findings suggest that inherited NOS2 deficiency was clinically silent in this patient until lethal infection with CMV. Moreover, NOS2 appeared to be redundant for control of other pathogens in this patient. (Funded by the National Center for Advancing Translational Sciences and others.).

Single position L5-S1 lateral ALIF with simultaneous robotic posterior fixation is safe and improves regional alignment and lordosis distribution index.

PURPOSE: Minimally invasive single position lateral ALIF at L5-S1 with simultaneous robot-assisted posterior fixation has technical and anatomic considerations that need further description. METHODS: This is a retrospective case series of single position lateral ALIF at L5-S1 with robotic assisted fixation. End points included radiographic parameters, lordosis distribution index (LDI), complications, pedicle screw accuracy, and inpatient metrics. RESULTS: There were 17 patients with mean age of 60.5 years. Eight patients underwent interbody fusion at L5-S1, five patients at L4-S1, two patients at L3-S1, and one patient at L2-S1 in single lateral position. Operative times for 1-level and 2-level cases were 193 min and 278 min, respectively. Mean EBL was 71 cc. Mean improvements in L5-S1 segmental lordosis were 11.7 ± 4.0°, L1-S1 lordosis of 4.8 ± 6.4°, sagittal vertical axis of - 0.1 ± 1.7 cm°, pelvic tilt of - 3.1 ± 5.9°, and pelvic incidence lumbar-lordosis mismatch of - 4.6 ± 6.4°. Six patients corrected into a normal LDI (50-80%) and no patients became imbalanced over a mean follow-up period of 14.4 months. Of 100 screws placed in lateral position with robotic assistance, there were three total breaches (two lateral grade 3, one medial grade 2) for a screw accuracy of 97.0%. There were no neurologic, vascular, bowel, or ureteral injuries, and no implant failure or reoperation. CONCLUSION: Single position lateral ALIF at L5-S1 with simultaneous robotic placement of pedicle screws by a second surgeon is a safe and effective technique that improves global alignment and lordosis distribution index.

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).

Homozygous NLRP1 gain-of-function mutation in siblings with a syndromic form of recurrent respiratory papillomatosis.

Juvenile-onset recurrent respiratory papillomatosis (JRRP) is a rare and debilitating childhood disease that presents with recurrent growth of papillomas in the upper airway. Two common human papillomaviruses (HPVs), HPV-6 and -11, are implicated in most cases, but it is still not understood why only a small proportion of children develop JRRP following exposure to these common viruses. We report 2 siblings with a syndromic form of JRRP associated with mild dermatologic abnormalities. Whole-exome sequencing of the patients revealed a private homozygous mutation in NLRP1, encoding Nucleotide-Binding Domain Leucine-Rich Repeat Family Pyrin Domain-Containing 1. We find the NLRP1 mutant allele to be gain of function (GOF) for inflammasome activation, as demonstrated by the induction of inflammasome complex oligomerization and IL-1ß secretion in an overexpression system. Moreover, patient-derived keratinocytes secrete elevated levels of IL-1ß at baseline. Finally, both patients displayed elevated levels of inflammasome-induced cytokines in the serum. Six NLRP1 GOF mutations have previously been described to underlie 3 allelic Mendelian diseases with differing phenotypes and modes of inheritance. Our results demonstrate that an autosomal recessive, syndromic form of JRRP can be associated with an NLRP1 GOF mutation.

Radiographic risk factors for intracranial hemorrhage in patients with left ventricular assist devices.

OBJECTIVE: Intracranial hemorrhage (ICH) in patients with left ventricular assist devices (LVAD) is a devastating complication. Demographic risk factors for ICH in LVAD patients are defined, however anatomic predispositions to ICH are unknown. We sought to interrogate intracranial radiographic risk factors for ICH in LVAD patients. METHODS: We reviewed 440 patients who received an LVAD from 2008-2021. We selected patients with CT scans of the head either before or after LVAD placement, but typically within 5 years. 288 patients (21 ICH, 267 Control) with imaging were included. A detailed chart review was performed on demographics, radiographic features, and management. RESULTS: The incidence of ICH in our total cohort was 8.6% (38/440). The presence of pump thrombosis (p=0.001), driveline infection (p=0.034), other hemorrhage (p=0.001), or previous placement of a cardio-defibrillator (p=.003) was associated with increased risk for ICH. An analysis of imaging revealed that the presence of a mass (p=0.006), vascular pathology (p=0.001), and microangiopathy (p=0.04) was significantly associated with ICH in LVAD patients. These radiographic features were validated with a multivariate logistic regression which confirmed presence of a mass (aOR 332.1, 95% CI: 14.7-7485.1, p<0.001), vascular pathology (aOR 69.7, 95% CI: 1.8-2658.8, p=0.022), and microangiopathy (aOR 6.5, 95% CI: 1.1-37.6, p=0.035) were independently associated with ICH. CONCLUSION: Radiographic evidence of microangiopathy, intracranial mass, and vascular pathology are independent risk factors for ICH which are readily identified by imaging. We advocate that CT imaging be used to further stratify patients at highest risk of ICH during treatment with an LVAD.

Is primary total hip arthroplasty in patients with Down's syndrome associated with increased complications at 2 years follow-up?

INTRODUCTION: Previous reports on primary total hip arthroplasty (THA) in patients with Down's syndrome (DS) are often small and/or lack a comparison cohort, and thus it is challenging to draw meaningful conclusions about this group. The purpose of this study was to report on the post-operative complications in patients with DS undergoing primary THA, compared to a non-DS cohort. METHODS: In this retrospective study, we evaluated patients from 2010 to 2018 using a national database. We assessed surgical complications: closed reduction for dislocation, revision, resection, periprosthetic fracture, and infection in patients with a diagnosis of DS undergoing primary THA and compared them to a THA group of patients without DS. Patients undergoing THA for hip fractures were excluded. Complications were evaluated at 90 days and 2 years. Multivariable logistic regression analysis was used to adjust for age, sex, body mass index, and Charlson comorbidity index. RESULTS: At 90 days patients with DS had an increased risk of revision (OR 3.1, CI 1.14-8.41), but no significant risk of resection (OR 5.24, CI 0.73-37.8), closed reduction (OR 2.03, CI 0.28-14.59), infection (OR 1.48, CI 0.6-3.62), or periprosthetic fracture (OR 1.97, CI 0.27-14.14). At 2 years patients with DS had an increased risk of periprosthetic fracture (OR 5.88, CI 1.84-18.78), but no significant increased risk of revision (OR 1.82, CI 0.66-5.01), resection (OR 2.37, CI 0.33-17.17), or infection (OR 0.65, CI 0.2-2.07). CONCLUSIONS: Primary THA in patients with DS is associated with increased 90-day revision, and periprosthetic fracture at 2 years.

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.

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.

Paget's Disease in Primary Total Hip Arthroplasty Is Associated With Greater In-Hospital Lengths of Stay, Costs, and Complications.

BACKGROUND: There are few well-powered studies investigating the association of Paget's disease of bone on patients undergoing primary total hip arthroplasty (THA). This study utilized a nationwide database to determine whether Paget's patients undergoing primary THA are associated with higher rates of (1) lengths of stay (LOS); (2) costs; and (3) complications (medical/surgical and implant-related). METHODS: Using International Classification of Diseases, Ninth Revision and Current Procedural Terminology codes, Paget's patients undergoing primary THA were identified and matched to non-Paget's patients in a 1:5 ratio by age, sex, and comorbidities utilizing the PearlDiver database. This resulted in 21,714 patients in Paget's (n = 3619) and non-Paget's (n = 18,095) cohorts. Outcomes assessed included LOS, episode-of-care costs, medical/surgical complications, and implant-related complications. A P value less than .003 was considered statistically significant. RESULTS: Compared to the matched cohort, Paget's patients undergoing primary THA had significantly longer LOS (P < .0001), higher 90-day total global episode-of-care costs (P < .0001), higher 90-day medical and surgical complications (P < .0001), and higher implant-related complications (P < .0001). CONCLUSION: We found that Paget's was associated with higher rates of LOS, costs, and complications. Although there was an association found, the risk appears reasonably low compared to the matched cohort. The study can be utilized by orthopedic professionals to counsel and educate these patients of potential complications which may occur following their procedure.

1.5-Stage Exchange Arthroplasty for Total Knee Arthroplasty Periprosthetic Joint Infections.

BACKGROUND: Periprosthetic joint infection (PJI) in total knee arthroplasty (TKA) is a challenging problem. The purpose of this study was to outline a novel technique to treat TKA PJI. We define 1.5-stage exchange arthroplasty as placing an articulating spacer with the intent to last for a prolonged time. METHODS: A retrospective review was performed from 2007 to 2019 to evaluate patients treated with 1.5-stage exchange arthroplasty for TKA PJI. Inclusion criteria included: articulating knee spacer(s) remaining in situ for 12 months and the patient deferring a second-stage reimplantation because the patient had acceptable function with the spacer (28 knees) or not being a surgical candidate (three knees). Thirty-one knees were included with a mean age of 63 years, mean BMI 34.4 kg/m2, 12 were female, with a mean clinical follow-up of 2.7 years. Cobalt-chrome femoral and polyethylene tibial components were used. We evaluated progression to second-stage reimplantation, reinfection, and radiographic outcomes. RESULTS: At a mean follow-up of 2.7 years, 25 initial spacers were in situ (81%). Five knees retained their spacer(s) for some time (mean 1.5 years) and then underwent a second-stage reimplantation; one of the five had progressive radiolucent lines but no evidence of component migration. Three knees (10%) had PJI reoccurrence. Four had progressive radiolucent lines, but there was no evidence of component migration in any knees. CONCLUSIONS: 1.5-stage exchange arthroplasty may be a reasonable method to treat TKA PJI. At a mean follow-up of 2.7 years, there was an acceptable rate of infection recurrence and implant durability.

Helmet Modification to PPE With 3D Printing During the COVID-19 Pandemic at Duke University Medical Center: A Novel Technique.

Care for patients during COVID-19 poses challenges that require the protection of staff with recommendations that health care workers wear at minimum, an N95 mask or equivalent while performing an aerosol-generating procedure with a face shield. The United States faces shortages of personal protective equipment (PPE), and surgeons who use loupes and headlights have difficulty using these in conjunction with face shields. Most arthroplasty surgeons use surgical helmet systems, but in the current pandemic, many hospitals have delayed elective arthroplasty surgeries and the helmet systems are going unused. As a result, the authors have begun retrofitting these arthroplasty helmets to serve as PPE. The purpose of this article is to outline the conception, design, donning technique, and safety testing of these arthroplasty helmets being repurposed as PPE.

Total Hip Arthroplasty in Patients With Dementia.

BACKGROUND: There are few studies evaluating total hip arthroplasty (THA) in patients with dementia. The purpose of this study is to evaluate the rate of revision, complication, emergency department (ED) visitation, and discharge disposition in patients with dementia undergoing THA. METHODS: In this retrospective study, we evaluated patients from 2007 to 2017 using a national database. We evaluated complications in patients with a diagnosis of dementia undergoing primary THA for osteoarthritis. RESULTS: In patients with dementia undergoing THA, the 90-day complications were increased risk of revision, delirium, ED visitation, and skilled nursing facility disposition (P < .05). In patients with dementia undergoing THA, the 2-year complications were increased risk of delirium, ED visitation, and skilled nursing facility disposition (P < .05). CONCLUSION: Patients with dementia undergoing THA are at an increased risk of complications and 90-day resource utilization.

Conversion of Hemiarthroplasty to THA Carries an Increased Risk of Reoperation Compared With Primary and Revision THA.

BACKGROUND: There is limited information on the complications and costs of conversion THA after hemiarthroplasty for femoral neck fractures. Previous studies have found that patients undergoing conversion THA experience higher risk complications, but it has been difficult to quantify the risk because of small sample sizes and a lack of comparison groups. Therefore, we compared the complications of patients undergoing conversion THA with strictly matched patients undergoing primary and revision THA. QUESTIONS/PURPOSES: (1) What are the risks of complications, dislocations, reoperations, revisions and periprosthetic fractures after conversion THA compared with primary and revision THA and how has this effect changed over time? (2) What are the length of hospital stay and hospital costs for conversion THA, primary THA, and revision THA? METHODS: Using a longitudinally maintained total joint registry, we identified 389 patients who were treated with conversion THA after hemiarthroplasty for femoral neck fractures between 1985 and 2014. The conversion THA cohort was 1:2 matched on age, sex, and year of surgery to 778 patients undergoing primary THA and 778 patients undergoing revision THA. The proportion of patients having at least 5-year followup was 73% in those who underwent conversion THA, 77% in those who underwent primary THA, and 76% in those who underwent revision THA. We observed a significant calendar year effect, and therefore, compared the three groups across two separate time periods: 1985 to 1999 and 2000 to 2014. We ascertained complications, dislocations, reoperations, revisions and periprosthetic fractures from the total joint registry. Cost analysis was performed using a bottom-up, microcosting methodology for procedures between 2003 and 2014. RESULTS: Patients who converted to THA between 1985 and 1999 had a higher risk of complications (hazard ratio [HR], 2.3; 95% confidence interval [CI], 1.7-3.1; p < 0.001), dislocations (HR, 2.3; 95% CI, 1.3-4.2; p = 0.007), reoperations (HR, 1.7; 95% CI, 1.2-2.5, p = 0.005), and periprosthetic fractures (HR, 3.8; 95% CI, 2.2-6.6; p < 0.001) compared with primary THA. However, conversion THAs during the 1985 to 1999 time period had a lower risk of reoperations (HR, 0.7; 95% CI, 0.5-1.0; p = 0.037), revisions (HR, 0.6; 95% CI, 0.5-0.9; p = 0.014), and periprosthetic fractures (HR, 0.6; 95% CI, 0.4-0.9; p = 0.007) compared with revision THA. The risk differences across the three groups were more pronounced after 2000, particularly when comparing conversion THA patients with revision THA. Conversion THA patients had a higher risk of reoperations (HR, 1.9; 95% CI, 1.0-3.4; p = 0.041) and periprosthetic fractures (HR, 1.7; 95% CI, 1.0-2.9; p = 0.036) compared with revision THA, but there were no differences in the complication risk (HR, 1.4; 95% CI, 0.9-2.1; p = 0.120), dislocations (HR, 1.5; 95% CI, 0.7-3.2; p = 0.274), and revisions (HR, 1.4; 95% CI, 0.7-3.0; p = 0.373). Length of stay for conversion THA was longer than primary THA (4.7 versus 4.0 days; p = 0.012), but there was no difference compared with revision THA (4.7 versus 4.5 days; p = 0.484). Similarly, total inpatient costs for conversion THA were higher than primary THA (USD 22,662 versus USD 18,694; p < 0.001), but there was no difference compared with revision THA (USD 22,662 versus USD 22,071; p = 0.564). CONCLUSIONS: Over the 30 years of the study, conversion THA has remained a higher risk procedure in terms of reoperation compared with primary THA, and over time, it also has become higher risk compared with revision THA. Surgeons should approach conversion THA as a challenging procedure, and patients undergoing this procedure should be counseled about the elevated risks. Furthermore, hospitals should seek appropriate reimbursement for these cases. LEVEL OF EVIDENCE: Level III, therapeutic study.

Infection After Unicompartmental Knee Arthroplasty: A High Risk of Subsequent Complications.

BACKGROUND: Unicompartmental knee arthroplasty restores function and improves pain in appropriately selected patients. Scant evidence exists regarding the treatment of periprosthetic joint infection (PJI) after unicompartmental knee arthroplasty (UKA). QUESTIONS/PURPOSES: (1) What was the overall survivorship free from reinfection? (2) What is the survivorship free of all-cause revision? (3) What are the Knee Society scores (KSS) and complications after surgical treatment of UKA PJI? METHODS: This retrospective study with data drawn from a longitudinally maintained institutional registry identified 15 UKA PJIs between 1992 and 2014. The median age at PJI diagnosis was 58 years (range, 41-82 years), nine of 15 were men, and the median body mass index was 29 kg/m (range, 23-36 kg/m). Ten patients (10 of 15) satisfied major Musculoskeletal Infection Society diagnostic criteria. There were five patients (five of 15) with early postoperative infections, five (five of 15) with acute hematogenous infections, and five (five of 15) with chronic PJIs. Two-stage exchange was performed in four patients with PJIs (four of 15), and débridement, antibiotics, and implant retention (DAIR) was performed in 11 patients (11 of 15) with PJIs. We performed Kaplan-Meier survivorship analysis for reinfection and revision procedures. Thirteen patients had a minimum of 2 years' followup and were included in the clinical analysis. Median followup was 4 years (range, 2-6 years). We calculated KSS. RESULTS: Infection-free survivorship was 71% at 5 years (95% confidence interval [CI], 46%-96%). Treatment success was higher for patients undergoing two-stage exchange (100% at 5 years; 95% CI, 100%-100%) versus DAIR (61% at 5 years; 95% CI, 31%-92%). Four of 11 patients undergoing DAIR had developed a reinfection at final followup. Survivorship free of any revision was 49% at 5 years (95% CI, 19%-79%). One patient from the two-stage exchange cohort underwent femoral component revision for aseptic loosening 5 years after PJI treatment, and two patients from the DAIR group were converted to TKA for disease progression at a mean of 4 years. In patients with a minimum of 2 years' followup, median KSS improved from 73 (range, 50-93) before index UKA to 94 (range, 55-100; p = 0.016). CONCLUSIONS: Treatment of UKA PJI with DAIR was associated with a lower infection-free survivorship at 5 years compared with two-stage exchange with conversion to TKA. Among those patients who were infection-free, a number needed reoperations for disease progression (in the DAIR group) or component loosening (in both groups). UKA PJI results in substantial morbidity, and patients with these infections should be followed closely for aseptic causes of failure in addition to infection recurrence. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Constrained Liner Revision Is Less Effective With Each Subsequent Constrained Liner Revision at Preventing Instability.

BACKGROUND: Constrained liners are used to treat recurring total hip arthroplasty dislocations in certain patients. Little is known about the fate of constrained liner revisions. The aim of this study is to evaluate the rate and survivorship free of revision for mechanical failure of constrained liners in patients who were revised to their first, second, and third constrained liners. METHODS: From 1989 to 2016, using our institution's total joint registry, we identified 554 revisions to a first constrained liner. Of the 554, 40 had mechanical failure of their index constrained liner and had revision to a second constrained liner. Of the 40, 13 had mechanical failure of their second constrained liner and had revision to a third constrained liner. Patients included in the failure analysis had minimum 2-year follow-up, with a mean follow-up of 5.5 years. RESULTS: In patients receiving their first, second, and third constrained liners, the survivorship free of revision for mechanical failure at 4 years was 90%, 52%, and 28%, respectively. Patients with a second and third constrained liner were more likely to have a revision for mechanical failure (second odds ratio 8, P < .0001; third odds ratio 10, P < .0001) compared to those receiving their first constrained liner. Using a different constrained liner did not decrease the risk of failure. CONCLUSION: After revision to a second or third constrained liner there is high rate of mechanical failure. When a total hip arthroplasty becomes unstable after constrained liner, surgeons should exercise caution before revising to another constrained liner.

High-energy Pediatric Scapula Fractures and Their Associated Injuries.

OBJECTIVES: The purpose of this study was to evaluate pediatric scapula fractures occurring in high-energy motorized vehicle accidents and their associated injury patterns in a pediatric patient population. METHODS: One thousand nine hundred sixty-eight pediatric patients who presented after either on-road or off-road motorized vehicle accidents between 1996 and 2015 were retrospectively reviewed. Thirty-eight patients were found to have scapula fractures and the remaining 1930 were identified as controls. RESULTS: A total of 39 scapula fractures occurred in 38 patients. The most common pattern was the AO/OTA 14-A3 (n=32), followed by 14-A2 (n=5), 14-B1 (n=1), and 14-C2 (n=1). Scapula fracture patients experienced higher rate of spine fractures (42% vs. 18%, P=0.001), skull fractures (26% vs. 12%, P=0.02), rib fractures (40% vs. 7.6%, P<0.0001), clavicle fractures (34% vs. 6%, P<0.0001), and upper extremity fractures (58% vs. 21%, P<0.0001) compared with controls. Scapula fracture patients had higher Injury Severity Scores (22.1 vs. 10.8, P<0.0001), thoracic injury (79% vs. 31%, P<0.0001), intracranial hemorrhage (32% vs. 15%, P=0.012), pneumothorax (55% vs. 8%, P<0.0001), and lung contusion (63% vs. 12%, P<0.0001). No difference in mortality was observed for scapula and control patients (5% vs. 2%, P=0.302). CONCLUSIONS: Pediatric scapula fractures were not associated with higher mortality rates in this series but were associated with significant morbidity as demonstrated by high rates of associated intracranial hemorrhage, skull fractures, thoracic injury, upper extremity fractures, and spine fractures compared with control patients. Surgeons who care for pediatric trauma patients should view scapula fractures as an indicator for more significant injuries. LEVEL OF EVIDENCE: Level III.

Conversion of Failed Hemiarthroplasty to Total Hip Arthroplasty Remains High Risk for Subsequent Complications.

BACKGROUND: Few studies have described the outcomes following conversion of failed hemiarthroplasties to total hip arthroplasty (THA) and the impact of mortality when estimating implant survivorship. The aims of this study were to evaluate the following: (1) the risks and predictors of complications, dislocations, reoperations, and revisions and (2) the extent of competing risk of death when evaluating outcomes in patients converted from hemiarthroplasty to THA. METHODS: The study comprised 389 patients treated with conversion THA following hemiarthroplasty for femoral neck fractures between 1985 and 2014. Revision rates were calculated using both the Kaplan-Meier method and cumulative incidence accounting for death as a competing risk. Risk factors were evaluated using Cox regression models. RESULTS: During an average 9.3 years of follow-up, there were 122 complications, 34 dislocations, 69 reoperations, and 51 revisions. Conversion for periprosthetic fractures was associated with a higher risk of reoperations (hazard ratio 4.30, 95% confidence interval 1.94-9.52). Increasing age was a risk factor for reoperations (hazard ratio 1.32, 95% confidence interval 1.10-1.59). No decrease in the rate of complications, dislocations, reoperations, or revisions was observed over the entire 30 years of the study either when evaluating year of surgery as a continuous variable or when comparing specific calendar year intervals (1985-1989, 1990-1999, 2000-2009, 2010-2014) (P > .05). Compared to the cumulative incidence accounting for the competing risk of death, the Kaplan-Meier method overestimated the risk of revision by 7% at 15 years and 10% at 20 years. CONCLUSION: Conversion from hemiarthroplasty to THA remains at high risk for subsequent complications. The cumulative incidence estimate provides a more accurate estimate of revision risk.