Left-digit bias in surgical decision-making for lumbar spinal stenosis.

BACKGROUND CONTEXT: Left-digit bias is a behavioral heuristic or cognitive "shortcut" in which the leftmost digit of a number, such as patient age, disproportionately influences surgical decisions. PURPOSE: To determine if left-digit bias in patient age influences the decision to perform arthrodesis with instrumentation vs decompression in lumbar spinal stenosis (LSS). DESIGN: Retrospective cohort. PATIENT SAMPLE: Patients with an ICD-10 diagnosis of lumbar stenosis or spondylolisthesis identified in the 2017-2021 National Surgical Quality Improvement Program (NSQIP) database. OUTCOME MEASURES: The primary outcome was the percent of patients who underwent arthrodesis with instrumentation (AwI). Matched age group comparisons without left-digit differences (ie, 76/77 vs 78/79, 80/81 vs 82/83, etc.) were performed to isolate the effect of the heuristic. Secondary outcomes including peri-operative events and complications were also compared within AwI and decompression cohorts. METHODS: Using CPT codes, procedures were classified as either AwI or decompression. Patients were grouped into 6 cohorts based on 2-year age windows (74/75, 76/77, 78/79, 80/81, 82/83, 84/85). The cohorts were propensity matched with neighboring age groups based on the presence of spondylolisthesis, demographics, and comorbidities. The primary comparison was between those aged 78/79 vs 80/81. RESULTS: After matching, the primary cohort consisted of two groups of 1,550 patients (aged 78/79 and 80/81). Patients aged 80/81 were less likely to undergo AwI than patients aged 78/79 (23.5% vs 27.2%, p=.021). AwI procedures occurred at similar rates between age groups with the same left digit. Within the decompression and AwI cohorts, there were no differences in secondary outcomes between patients aged 78/79 and 80/81. CONCLUSIONS: LSS patients aged 80/81 are less likely to undergo AwI than patients aged 78/79, regardless of comorbidities. This was not seen when comparing patients with similar left digits in age. Until objective measures of physiologic capacity are established, left-digit bias may influence clinical decisions.

Is There an Implicit Racial Bias in the Case Order of Elective Total Joint Arthroplasty?

INTRODUCTION: Identifying ways to improve equitable access to healthcare is of the utmost important. In this study, we analyzed whether patient race was negatively associated with surgical start times for total joint arthroplasties (TJA). METHODS: The surgical case order and start times of all primary TJAs performed at a large academic medical center between May 2014 and May 2018 were retrospectively reviewed. Patients were included if > 21, had a documented self-reported race, and were operated on by an arthroplasty fellowship-trained surgeon. Operations were categorized as first-start, early (7:00 AM-11:00 AM), mid-day (11:00 AM-3:00 PM), or late (after 3:00 PM). Multivariable logistic regression (MLR) was performed, and odds ratios (OR) were calculated. RESULTS: This study identified 1663 TJAs-871 total knee (TKA) and 792 total hip arthroplasties (THA) who met inclusion criteria. Overall, there was no association between race and surgical start time. Upon sub-analysis by surgical type, this held true for TKA patients, but self-identifying Hispanic and non-Hispanic Black patients undergoing THA were more likely to have later surgical start times (ORs: 2.08 and 1.88; p < 0.05). DISCUSSION: Although there was no association between race and overall TJA surgical start times, patients with marginalized racial and ethnic identities were more likely to undergo elective THA later in the surgical day. Surgeons should be aware of potential implicit bias when determining case order to potentially prevent adverse outcomes due to staff fatigue or lack of proper resources later in the day.

How Much Protection Does a Collar Provide? Assessing Risk of Early Periprosthetic Femur Fractures Following Total Hip Arthroplasty in Elderly Patients.

BACKGROUND: Periprosthetic fractures (PPFs) account for approximately 25% of early revisions following total hip arthroplasty (THA). Cemented femoral fixation is associated with a lower-risk of PPF, and collared-cementless stems may reduce the risk as well. The objective of this study was to compare early-PPF rates between cemented, collared-cementless, and non-collared cementless stems in elderly patients. METHODS: A consecutieve-series of 11,522 primary THAs performed between 2016 and 2021 at our institution in patients >65 years of age was identified. Stem types used were categorized as cemented, collared-cementless, or non-collared cementless. Patients undergoing THA who had cemented-stems were older, more commonly women, and more likely to have a posterior-approach. To reduce confounding of patient characteristics, we matched patients in the 3 stem-categories according to age, sex, and body mass index. This generated 3-groups (cemented, collared-cementless, and non-collared cementless) consisting of 936 patients per group. The mean age of these 2,808 patients was 73 years, the mean body mass index was 27, and 67% were women. Logistic regressions were used to evaluate risk-factors for early-PPF. In the entire cohort of primary THA in elderly patients, there were 85 early PPFs (0.7%) over the study period. RESULTS: Non-collared cementless stems were associated with an increased risk of early PPF (OR: 3.11; P = .03) compared to collared-cementless stems. There were no early PPFs in the matched cemented cohort, 6 early PPFs in the matched collared-cementless cohort, and 16 early-PPFs in the matched non-collared cementless cohort (0% versus 0.64% versus 1.71%, P < .001). CONCLUSIONS: In this large-series of patients >65 years of age undergoing primary THA, cemented stem fixation had the lowest incidence of early PPF, but collared-cementless stems had a nearly 3-fold decrease in risk for early PPF compared to non-collared cementless stems.

The Association of Lumbar Plexus Lengthening with Neurologic Deficit After Adult Spinal Deformity Surgery.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: This study aimed to evaluate the association between nerve lengthening after adult deformity correction and motor deficits dervied from the upper lumbar plexus or femoral nerve. SUMMARY OF BACKGROUND DATA: Adult spinal deformity (ASD) surgery is associated with high rates of neurological deficits. Certain postoperative deficits may be related to lengthening of the upper lumbar plexus (ULP) and/or femoral nerve (FN) after correction of lumbar deformity. METHODS: Patients with ASD who underwent posterior-only corrective surgery from the sacrum to L3 or above were included. The length of each lumbar nerve root (NR) was calculated geometrically using the distance from the foramen to the midpoint between the anterosuperior iliac crest and pubic symphysis on AP and lateral radiographs. The mean lengths of the L1-3 and L2-4 NRs were used to define the lengths of the ULP and FN, respectively. Pre- to postoperative changes in nerve length were calculated. Neurological examination was performed at discharge. Proximal weakness (PW) was defined as the presence of weakness compared to baseline in either hip flexors or knee extensors. Multiple linear regression analysis was used for estimating the postoperative lengthening according to the magnitude of preoperative curvature and postoperative correction angles. RESULTS: A total of 202 sides were analyzed in 101 patients, and PW was present on 15 (7.4%) sides in 10 patients. Excluding the 10 cases with three-column osteotomies, those with PW had a significantly higher rate of pure sagittal deformity (P<.001) and greater nerve lengthening than those without PW (ULP 24 vs 15 mm, P=0.02; FN 18 vs 11 mm, P=0.05). No patient had advanced imaging showing neural compression, and complete recovery of PW occurred in 8 patients at 1-year follow-up. CONCLUSIONS: After ASD surgery, lengthening of the ULP was associated with PW. In preoperative planning, surgeons must consider how the type of correction may influence the risk for nerve lengthening, which may contribute to postoperative neurologic deficit. LEVEL OF EVIDENCE: 3.

Genetic Risk Factors for End-Stage Hip Osteoarthritis Treated With Total Hip Arthroplasty: A Genome-wide Association Study.

BACKGROUND: Although a genetic component to hip osteoarthritis (OA) has been described, focused evaluation of the genetic components of end-stage disease is limited. We present a genomewide association study for patients undergoing total hip arthroplasty (THA) to characterize the genetic risk factors associated with end-stage hip osteoarthritis (ESHO), defined as utilization of the procedure. METHODS: Patients who underwent primary THA for hip OA were identified in a national patient data repository using administrative codes. Fifteen thousand three hundred and fifty-five patients with ESHO and 374,193 control patients were identified. Whole genome regression of genotypic data for patients who underwent primary THA for hip OA corrected for age, sex, and body mass index (BMI) was performed. Multivariate logistic regression models were used to evaluate the composite genetic risk from the identified genetic variants. RESULTS: There were 13 significant genes identified. Composite genetic factors resulted in an odds ratio 1.04 for ESHO (P < .001). The effect of genetics was lower than that of age (Odds Ratio (OR): 2.38; P < .001) and BMI (1.81; P < .001). CONCLUSION: Multiple genetic variants, including 5 novel loci, were associated with end-stage hip OA treated with primary THA. Age and BMI were associated with greater odds of developing end-stage disease when compared to genetic factors.

Unexpected positive intraoperative cultures (UPIC) at index osseointegration do not lead to increased postoperative infectious events.

Introduction: The most common complication following transcutaneous osseointegration for amputees is infection. Although an obvious source of contamination is the permanent stoma, operative site contamination at the time of implantation may be an additional source. This study investigates the impact of unexpected positive intraoperative cultures (UPIC) on postoperative infection. Methods: Charts were reviewed for 8 patients with UPIC and 22 patients with negative intraoperative cultures (NIC) who had at least 1 year of post-osseointegration follow-up. All patients had 24 h of routine postoperative antibiotic prophylaxis, with UPIC receiving additional antibiotics guided by culture results. The main outcome measure was postoperative infection intervention, which was graded as (0) none, (1) antibiotics unrelated to the initial surgery, (2) operative debridement with implant retention, or (3) implant removal. Results: The UPIC vs. NIC rate of infection management was as follows: Grade 0, 6/8 = 75 % vs. 14/22 = 64 %, p = 0.682; Grade 1, 2/8 = 25 % vs. 8/22 = 36.4 % (Fisher's p = 0.682); Grade 2, 1/8 = 12.5 % vs. 0/22 = 0 % (Fisher's p = 0.267); Grade 3, 0/8 = 0 % vs. 1/22 = 4.5 % (Fisher's p = 1.000). No differences were statistically significant. Conclusions: UPIC at index osseointegration, managed with directed postoperative antibiotics, does not appear to increase the risk of additional infection management. The therapeutic benefit of providing additional directed antibiotics versus no additional antibiotics following UPIC is unknown and did not appear to increase the risk of other adverse outcomes in our cohort.

Characterization of Genetic Risk of End-Stage Knee Osteoarthritis Treated with Total Knee Arthroplasty: A Genome-Wide Association Study.

BACKGROUND: End-stage knee osteoarthritis (OA) is a highly debilitating disease for which total knee arthroplasty (TKA) serves as an effective treatment option. Although a genetic component to OA in general has been described, evaluation of the genetic contribution to end-stage OA of the knee is limited. To this end, we present a genome-wide association study involving patients undergoing TKA for primary knee OA to characterize the genetic features of severe disease on a population level. METHODS: Individuals with the diagnosis of knee OA who underwent primary TKA were identified in the U.K. Biobank using administrative codes. The U.K. Biobank is a data repository containing prospectively collected clinical and genomic data for >500,000 patients. A genome-wide association analysis was performed using the REGENIE software package. Logistic regression was also used to compare the total genetic risk between subgroups stratified by age and body mass index (BMI). RESULTS: A total of 16,032 patients with end-stage knee OA who underwent primary TKA were identified. Seven genetic loci were found to be significantly associated with end-stage knee OA. The odds ratio (OR) for developing end-stage knee OA attributable to genetics was 1.12 (95% confidence interval [CI], 1.10 to 1.14), which was lower than the OR associated with BMI (OR = 1.81; 95% CI, 1.78 to 1.83) and age (OR = 2.38; 95% CI, 2.32 to 2.45). The magnitude of the OR for developing end-stage knee OA attributable to genetics was greater in patients <60 years old than in patients ≥60 years old (p = 0.002). CONCLUSIONS: This population-level genome-wide association study of end-stage knee OA treated with primary TKA was notable for identifying multiple significant genetic variants. These loci involve genes responsible for cartilage development, cartilage homeostasis, cell signaling, and metabolism. Age and BMI appear to have a greater impact on the risk of developing end-stage disease compared with genetic factors. The genetic contribution to the development of severe disease is greater in younger patients. LEVEL OF EVIDENCE: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Survivorship and Risk Factors for Re-Revision after Aseptic Revision Total Hip Arthroplasty in Patients Aged ≤55 Years.

BACKGROUND: There is a relative paucity of literature on the outcomes after revision total hip arthroplasty (rTHA) in young patients. This study reports the survivorship and risk factors for re-revision in patients aged ≤55 years. METHODS: We identified 354 patients undergoing aseptic nononcologic rTHA at mean follow-up of 5 years after revision, with mean age of 48 years, body mass index of 28 kg/m2, and 64% female. Thirty-five (10%) patients underwent at least 1 previous rTHA. The main indications for rTHA included wear/osteolysis (21%), adverse local tissue reaction (21%), recurrent instability (20%), acetabular loosening (16%), and femoral loosening (7%); and included acetabular component-only rTHA in 149 patients (42%), femoral component-only rTHA in 46 patients (13%), both component rTHA in 44 patients (12%), and head/liner exchanges in patients 115 (33%). The Kaplan-Meier method was used to measure survivorship free from re-revision THA, and multivariate regression was used to identify risk factors for re-revision THA. RESULTS: Sixty-two patients (18%) underwent re-revision THA at the mean time of 2.5 years, most commonly for instability (37%), aseptic loosening (27%), and prosthetic joint infection (15%). The rTHA survivorship from all-cause re-revision and reoperation was 83% and 79% at 5 years, respectively. Multivariate analysis demonstrated that patients undergoing femoral component only (hazard ratio 4.8, P = .014) and head/liner exchange rTHA (hazard ratio 2.5, P = .022) as risk factors for re-revision THA. CONCLUSION: About 1 in 5 patients aged ≤55 years undergoing rTHA required re-revision THA at 5 years, most commonly for instability. The highest risk group included patients undergoing head/liner exchanges and isolated femoral component revisions.

Classification(s) of Cervical Deformity.

Cervical spine deformities (CSD) are complex surgical issues with currently heterogenous management strategies. The classification of CSD is still an evolving field. Rudimentary classification schemas were initially proposed in the late 20th century but were largely informal and based on the underlying etiology (i.e. , postsurgical, traumatic, or inflammatory). The first formal classification schema was proposed by Ames et al. in 2015 who established a standard nomenclature for describing these deformities. This classification system established 5 deformity descriptors based on curve apex location (cervical, cervicothoracic, thoracic, craniovertebral junctional, and coronal deformities) and 5 deformity modifiers which helped surgeons utilize a standard language when discussing CSD patients. Koller et al. in 2019 subsequently established a classification system for patients with rigid cervical kyphosis based on regional and global sagittal alignment. Most recently, Kim et al. in 2020 proposed an updated classification system utilizing dynamic cervical spine imaging to guide surgical treatment of CSD patients. It identified 4 major groups of deformities - (1) those with "flat-neck" deformities caused by cervical lordosis T1 slope mismatch; (2) those with focal kyphotic deformities between 2 cervical vertebrae; (3) those with cervicothoracic deformities caused by large T1 slope; and (4) those with coronal deformities. Group 2 deformities most often required combined anterior-posterior approaches with short constructs, and group 3 deformities most often required posterior-only approaches with 3-column osteotomies.

The history of orthopaedic surgery in India: from antiquity to present.

Indian orthopedists have a legacy dating back more than 4000 years. Starting with the Harappan civilization, ancient orthopaedic surgeons reduced fractures and conducted therapeutic trepanations. Since then, Indian physicians have pioneered many of the orthopaedic techniques still used today - including the use of prosthetics, fracture tables, and rehabilitative physical therapy. Today, orthopaedic surgeons coexist with traditional Indian bonesetters. Although bonesetting practices can have complication rates as high as 40%, bonesetters still handle a majority of fractures in India and are often culturally preferred. Importantly though, bonesetters are often the only expedient option available in both rural and urban settings.

Intraoperative Scrub Nurse Handoffs Are Associated with Increased Operative Times for Lower Extremity Orthopaedic Sports Procedures.

PURPOSE: The purpose of this study was to evaluate the effect of intraoperative scrub nurse handoffs on surgical times for arthroscopically-assisted anterior cruciate ligament (ACL) reconstructions and hip arthroscopies. METHODS: A retrospective chart review was done at a major, urban academic medical center for all patients who underwent arthroscopically-assisted ACL reconstructions and hip arthroscopies for femoroacetabular impingement syndrome between May 2014 and May 2020. All ACL reconstructions were performed by 1 of 6 sports medicine fellowship-trained surgeons, and all hip arthroscopies were performed by a single surgeon. Operative times, number of scrub nurse handoffs, surgeon, patient demographics, and procedure-specific information were recorded. The association between patient characteristics and the number of handoffs, as well as the association between patient characteristics and operative times, stratified by scrub nurse handoffs, were calculated. A multivariable linear regression was performed to assess the association between intra-operative handoffs and operative times. RESULTS: Eight hundred twenty ACL reconstructions and 269 hip arthroscopies were identified. Multivariable linear regression demonstrated increasing intraoperative scrub nurse handoffs were associated with increased operative times for all patients. For ACL reconstructions, when including all possible covariates, 1 scrub nurse handoff increased operative times by 21.1 minutes (95% confidence interval [CI]: 15.36 to 26.89; P < .001), and 2+ handoffs increased operative times by 34.2 minutes (95% CI: 26.28 to 42.15; P < .001). For hip arthroscopies, 1 scrub nurse handoff increased operative times by 7.0 minutes (95% CI: 0.31 to 13.74; P = .04). CONCLUSION: Although a causal link cannot be made, intraoperative scrub nurse handoffs were associated with statistically significant increase in operative times for both ACL reconstructions and hip arthroscopies. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Intraoperative Scrub Nurse Handoffs Are Associated With Increased Operative Times for Total Joint Arthroplasty Patients.

BACKGROUND: Surgeons typically remain scrubbed in for the duration of a surgical case, while scrub nurses are shift-workers who handoff mid-operation. These handoffs can intuitively create inefficiencies, but currently, no orthopedic research has studied the impact of these handoffs. This study analyzed the effect of intraoperative scrub nurse handoffs on operative times for total joint arthroplasties (TJAs). METHODS: A retrospective chart review was performed for primary total hip (THA) and total knee arthroplasties (TKA) performed between May 2014 and May 2018. Operative times, number of scrub nurse handoffs, surgeon, and patient information were collected. A multivariable linear regression was performed to assess the association between patient and surgeon characteristics, intraoperative handoffs, and operative times. RESULTS: A total of 1109 TKA and 1032 THA patients were identified. Multivariable linear regression demonstrated that for TKAs, 1 handoff was associated with a 3.89-minute longer operative time (P value = .02), and 2+ handoffs were associated with a 15.99-minute longer case (P value < .001). For THA patients, 1 handoff was associated with a 6.20-minute longer operative time (P value < .001), and 2+ handoffs were associated with an 18.52-minute longer case (P value < .001). CONCLUSIONS: Although causation cannot be established, when controlling for multiple confounders, intraoperative scrub nurse handoffs were associated with statistically significant increases in operative times for TJAs. Optimizing scrub nurse staffing models to decrease intraoperative handoffs could thus have practical ramifications on TJA patients.

Effects of Skilled Nursing Facility Partnerships on Outcomes Following Total Joint Arthroplasty.

INTRODUCTION: Post-total joint arthroplasty (TJA) discharge to a skilled nursing facility (SNF) is associated with higher costs and more complications than home discharge; however, some patients still require postoperative SNF care. To improve outcomes for patients requiring postoperative SNF care, this article analyzed the effect of SNF-surgeon partnerships on TJA postoperative costs and patient outcomes. METHODS: This was a retrospective study of primary TJA patients who were part of Medicare's Comprehensive Care for Joint Replacement (CJR) pilot program at our urban, academic medical center. We identified all patients discharged to SNF and designated SNFs as "preferred" if they maintained a partnership with our surgical team. SNF costs, total 90-day postoperative costs, average length of stay in SNF, 90-day readmission rates, and readmission diagnoses were recorded. Data were compared using Student t-tests. Readmission rates and the presence of a readmission diagnosis were analyzed using z-scores. RESULTS: Our search identified 189 patients (22.9%) discharged to SNFs, with 128 (67.8%) discharged to preferred and 61 (32.2%) discharged to nonpreferred facilities. Over the 4-year CJR pilot program, SNF costs ($10,981.23 versus $7,343.34; P < 0.005) and overall postdischarge costs ($23,952.52 versus $18,339.26; P = 0.07) were higher for patients discharged to nonpreferred SNFs versus preferred SNFs. Patients discharged to nonpreferred SNFs also had increased length of stay (14.8 versus 10.1 days; P < 0.005) and increased readmission rates (19.7% versus 3.9%; P < 0.005). These differences became more pronounced across the study period. CONCLUSION: For patients undergoing primary TJA, hospital partnership with SNFs can improve CJR performance by cost reduction and overall outcomes for TJA patients.

Postoperative COVID-19 Pneumonia following Resection of a Large Thoracic Chondrosarcoma.

CASE: A 57-year-old man presenting with two months of insidious shoulder pain was found to have a large thoracic chondrosarcoma invading the spinal canal. The patient's orthopedic oncologist organized an interdisciplinary team including interventional radiology, thoracic surgery, neurosurgery, and plastic surgery. This allowed safe, en bloc tumor resection. The patient's postoperative course was complicated by COVID-19 pneumonia, which was rapidly identified and medically managed with full recovery. CONCLUSION: Postoperative COVID-19 pneumonia can present insidiously and mimic other postoperative complications. Early identification and testing can promote rapid isolation, proper personal protective equipment use, and guide outcome-improving treatments.

Timing and Tips for Total Hip Arthroplasty in a Critically Ill Patient With Coronavirus Disease 2019 and a Femoral Neck Fracture.

Expedited time to surgery after hip fracture is associated with decreased morbidity and mortality in appropriately optimized patients. However, the optimal timing of surgery in patients with the novel coronavirus disease 2019 (COVID-19) infection remains unknown. This case report describes a patient with COVID-19 pneumonia complicated by multiorgan system failure requiring intubation who sustained a femoral neck fracture that required total hip arthroplasty. This patient had a significant, deliberate delay in time to surgical intervention because of his critical state. When deciding the optimal timing for total hip arthroplasty in patients with COVID-19, we recommend using inflammatory markers, such as procalcitonin and interleukin-6, as indicators of disease resolution and caution operative intervention when patients are nearing the 7-10th day of COVID-19 symptoms. Furthermore, implant cementation and spinal anesthesia in critically ill COVID-positive patients should be approached cautiously in the setting of pulmonary disease and multiorgan system failure. Close follow-up with medical doctors is recommended to minimize long-term sequelae and delay to baseline mobility.

Opioid Prescription Consumption Patterns After Total Joint Arthroplasty in Chronic Opioid Users Versus Opioid Naive Patients.

Although chronic preoperative opioid use has been linked to inferior total joint arthroplasty outcomes, little research exists on postoperative prescribing patterns for opioid-naive orthopaedic patients versus chronic opioid users. Method: The New York State Prescription Monitoring Program database, which tracks controlled prescriptions dispensed in-state over the preceding 12 months, was retrospectively queried for 386 patients who underwent primary, elective total hip or knee arthroplasty at a high-volume, urban medical center from May through December 2017. Seventy-four patients were excluded because they did not return prescription monitoring program results, leaving 312 patients. Prescribers, medications, dates prescribed and filled, and quantity dispensed were recorded 3 months preoperatively through 12 months postoperatively. We defined chronic users as ≥2 opioid prescriptions filled in 3 preoperative months and opioid-naive as <2 filled. Opioid use was compared univariately using 2-tailed Student t-tests. Results: Chronic opioid users (n = 49; 15.7%) filled an average of 13,006.64 morphine equivalent doses per patient in the 12-month postoperative period, while opioid-naive users (n = 263; 84.3%) filled an average of 854.48 morphine equivalent doses per patient (P < 0.01). Opioid use in the chronic-user group was significantly higher in each 6-week postoperative interval (P < 0.01). These trends remained significant when stratified by procedure. For opioid-naive patients, 74% of opioid prescriptions were prescribed by our orthopaedic department. For chronic users, only 21% of opioid prescriptions originated from our department. Chronic users were found to cyclically fill opioid prescriptions every 3 to 4 weeks postoperatively as far out as 12 months and were significantly more likely to fill nonopioid controlled substance prescriptions both preoperatively and postoperatively (P < 0.01). Discussion: Chronic opioid users undergoing arthroplasty filled significantly more opioid prescriptions than opioid-naive patients. Chronic users obtained prescriptions from myriad sources, only a minority of which originated from our orthopaedic department. In the current opioid epidemic, vigilance regarding opioid prescribing is critical.

Deeper Central Reaming May Enhance Initial Acetabular Shell Fixation.

BACKGROUND: The initial stability of press-fit acetabular components is partially determined by the reaming technique. Nonhemispherical (NHS) acetabular shells, which have a larger radius at the rim than the dome, often require larger reaming preparations than the same-sized hemispherical (HS) shells. Furthermore, deeper central reaming may provide a more stable press fit. Using a reproducible, in vitro protocol, we compared initial shell stability under different reaming techniques with HS and NHS acetabular components. METHODS: Cavities for 54-mm NHS and 56-mm HS acetabular components were premachined in 20-pcf Sawbones blocks. Acetabular cavities included diameters of 54, 55, "54+," and "55+". "+" indicates a cavity with a 2-mm smaller diameter that is 2-mm deeper. A 4750N statically applied force seated shells to a height that was comparable with shell height after an orthopaedic surgeon's manual impaction. Force required to dislodge shells was assessed via a straight torque-out with a linear load. RESULTS: Increased preparation depth (+) was associated with deeper shell seating in all groups. Deeper central reaming increased required lever-out force for all groups. Overall, HS and NHS implants prepared with 55 + preparation had the highest lever-out forces, although this was not significantly higher than those with 54+. CONCLUSIONS: In 20-pcf Sawbones, representing dense bone, overreaming depth by 1-mm improved initial seating measurements. In both HS and NHS acetabular shells, seating depth and required lever-out force were higher in the "+" category. It is unclear, however, whether a decreased diameter ream increased seating stability (55+ vs 54+). Clinically, this deeper central reaming technique may help initial acetabular stability.

Single vector platform vaccine protects against lethal respiratory challenge with Tier 1 select agents of anthrax, plague, and tularemia.

Bacillus anthracis, Yersinia pestis, and Francisella tularensis are the causative agents of Tier 1 Select Agents anthrax, plague, and tularemia, respectively. Currently, there are no licensed vaccines against plague and tularemia and the licensed anthrax vaccine is suboptimal. Here we report F. tularensis LVS ΔcapB (Live Vaccine Strain with a deletion in capB)- and attenuated multi-deletional Listeria monocytogenes (Lm)-vectored vaccines against all three aforementioned pathogens. We show that LVS ΔcapB- and Lm-vectored vaccines express recombinant B. anthracis, Y. pestis, and F. tularensis immunoprotective antigens in broth and in macrophage-like cells and are non-toxic in mice. Homologous priming-boosting with the LVS ΔcapB-vectored vaccines induces potent antigen-specific humoral and T-cell-mediated immune responses and potent protective immunity against lethal respiratory challenge with all three pathogens. Protection against anthrax was far superior to that obtained with the licensed AVA vaccine and protection against tularemia was comparable to or greater than that obtained with the toxic and unlicensed LVS vaccine. Heterologous priming-boosting with LVS ΔcapB- and Lm-vectored B. anthracis and Y. pestis vaccines also induced potent protective immunity against lethal respiratory challenge with B. anthracis and Y. pestis. The single vaccine platform, especially the LVS ΔcapB-vectored vaccine platform, can be extended readily to other pathogens.