Effects of fluid composition in fluid injection experiments in porous media.

Experiments on fluid flow in porous media, using fluids loaded with solids of various grain sizes, have been conducted in a modified Hele-Shaw setup. This setup utilised weakly cemented porous media with specific hydraulic and mechanical properties. Fluid injection in coarse granular media with clean or low-concentration fine particles, results in infiltration only, with pressure close to the material tensile strength, while injection in finer granular material causes damage alongside infiltration, with the fluid pressure still close to the material tensile strength. When larger particle sizes or higher particle concentrations are used in the mixture, the fluid travels further within the porous medium, primarily influenced by the grain size of the granular medium. In the latter case, the Darcy flow equation with an effective permeability term can be employed to determine the pressure differential. For the largest particle sizes included in the fluid, the equation is still applicable, but the effective permeability requires adjustment for particle size within the fluid rather than the granular medium. This is crucial when the injection point is locally clogged. The experiments show that fracturing conditions are controlled by different mechanisms. Dimensional and statistical analysis was used to classify the injection pressures to regimes predicted by fracturing theory or by Darcy law with modified effective permeabilities. The findings show that both the material properties and fluid composition are important designing parameters.

Accuracy of intraoperative approximation of pelvic tilt using preoperative standing radiographs.

Background: Anterior approach surgeons who utilize intraoperative fluoroscopy often try to match a preoperative radiograph as a reference for intraoperative cup position. Every degree of inaccuracy in tilt leads to a roughly 0.7° change in anteversion. This study aimed to determine how closely pelvic tilt (PT) is approximated intraoperatively when compared to preoperative anteroposterior (AP) radiographs. Methods: This was a retrospective review of 193 primary THA's done by 2 surgeons at an academic tertiary referral center between September 2021-January 2023. There were 24 patients excluded for distorted anatomy, post-traumatic arthritis, insufficient x-rays, or a sacroiliac joint that could not be visualized on film. Data collected included age and BMI. PT was calculated using the formula, Tilt = -(ln((B/A) x (1/0.483)))/0.051. Value A is the distance from the base of the SI joint to the superior margin of the obturator foramen; value B is the height of the obturator foramen. Results: Mean preoperative PT was 0.2° versus intraoperative PT was 3.4° (p < 0.001). Mean absolute difference was 6.5°. 48% of patients (n = 81) had an absolute difference less than 5°, 31% (n = 52) between 5° and 10°, 14% (n = 24) between 10° and 15°, and 7% (n = 12) greater than 15°. There was no correlation between BMI or age and PT discrepancy. Conclusion: Of the patients, 21% had a discrepancy of 10° or greater between their preoperative radiographs and intraoperative fluoroscopic images. Surgeons should be aware of potential errors in cup positioning and be particularly diligent in high-risk cases.

Coronal and Sagittal Component Position in Contemporary Total Knee Arthroplasty: Targeting Native Alignment Optimizes Clinical Outcomes.

BACKGROUND: Advanced technologies, like robotics, provide enhanced precision for implanting total knee arthroplasty components; however, optimal component position and limb alignment remain unknown. This study sought to identify sagittal and coronal alignment targets that correlate with minimal clinically important differences (MCIDs) in patient-reported outcome measures (PROMs). METHODS: A total of 1,311 consecutive total knee arthroplasties were retrospectively reviewed. Posterior tibial slope (PTS), femoral flexion (FF), and tibio-femoral alignment (TFA) were measured radiographically. Patients were grouped based on whether they achieved multiple MCIDs for PROM scores. Classification and regression tree machine learning models were utilized to identify optimal alignment zones. The mean follow-up was 2.4 years (range, 1 to 11). RESULTS: The change in PTS and postoperative TFA were most predictive for achieving MCIDs in 90% of the models. Approximating native PTS within 4° correlated with MCID achievement and superior PROMs. Preoperative varus and neutral aligned knees were more likely to meet MCIDs and superior PROM scores when not overcorrected into valgus postoperatively (≥7°). Preoperative valgus-aligned knees correlated with MCID achievement when postoperative TFA was not overcorrected into substantial varus (<0°). Albeit less impactful, FF ≤ 7° correlated with MCID achievement and superior PROMs regardless of preoperative alignment. Sagittal and coronal alignment measurements had moderate to strong interactions in 13 of 20 models. CONCLUSION: Optimized PROM MCIDs correlated with approximating native PTS while maintaining similar preoperative TFA and incorporating moderate FF. Study findings demonstrate interactions between sagittal and coronal alignment which may optimize PROMs, highlighting the importance of three-dimensional implant alignment targets. LEVEL OF EVIDENCE: III.

Cost Analysis of Conversion Total Knee Arthroplasty: A Multi-Institutional Database Study.

BACKGROUND: Total knee arthroplasty (TKA) after prior knee surgery, also known as conversion TKA (convTKA), has been associated with higher complications, resource utilization, time, and effort. The increased surgical complexity of convTKA may not be reflected by the relative value units (RVUs) assigned under the current U.S. coding guidelines. The purpose of this study was to compare the RVUs of primary TKA and convTKA and to calculate the RVU per minute to account for work effort. METHODS: The American College of Surgeons National Surgical Quality Improvement Project (NSQIP) database was analyzed for the years 2005 to 2020. Current Procedural Terminology (CPT) code 27447 alone was used to identify patients who underwent primary TKA, and 27447 plus 20680 were used to identify convTKA. After 1:1 propensity score matching, 1,600 cases were assigned to each cohort. The 2023 Medicare Physician Fee Schedule RVU-to-dollar conversion factor from the U.S. Centers for Medicare & Medicaid Services (CMS) was used to calculate RVU dollar valuations per operative time. Complication rates were compared using a multivariate logistic regression model controlling for baseline characteristics. RESULTS: The mean operative time for TKA was 97.8 minutes, with a corresponding RVU per minute of 0.25, while the mean operative time for convTKA was 124.3 minutes, with an RVU per minute of 0.19 (p < 0.0001). Using the conversion factor of $33.06 per RVU, this equated to $8.11 per minute for TKA versus $6.39 per minute for convTKA. ConvTKA was associated with higher overall complication (10.9% versus 6.5%, p < 0.0001), blood transfusion (6.6% versus 3.7%, p < 0.01), reoperation (2.3% versus 0.94%, p < 0.0001), and readmission (3.7% versus 1.8%, p < 0.001) rates. CONCLUSIONS: The current billing guidelines lead to lower compensation for convTKA despite its increased complexity. The longer operative time, higher complication rate, and increased resource utilization may incentivize providers to avoid performing this operation. CPT code revaluation is warranted to reflect the time and effort associated with this procedure. LEVEL OF EVIDENCE: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Reliability of the Modified Radiographic Union Score for Tibia Fractures (mRUST) for Femoral Shaft Fractures.

OBJECTIVES: To evaluate the interobserver and intraobserver reliability of the modified Radiographic Union Score for Tibia Fractures (mRUST) and the effect of rater experience in evaluation of femoral fractures. DESIGN: Retrospective cohort study. SETTING: Single Level 1 trauma center. PATIENTS/PARTICIPANTS: Patients 18-55 years of age with a femur shaft fracture. INTERVENTION: Intramedullary nail fixation. MAIN OUTCOME MEASUREMENT: Interobserver and intraobserver reliability using the intraclass correlation coefficient. RESULTS: The overall interobserver reliability was 0.96. Among fellowship-trained evaluators, the interobserver reliability was 0.94, and it was 0.92 among trainees. The overall intraobserver reliability was 0.98. The intraobserver reliability was 0.97 among fellowship-trained evaluators and 0.96 for trainees. CONCLUSIONS: These results show high interobserver and intraobserver reliability of mRUST in the evaluation of radiographic healing for femur shaft fractures treated with intramedullary nail. This high reliability was further demonstrated throughout different postoperative healing time frames. In addition, mRUST appears to be reliable when used both by trainees and experienced surgeons for the evaluation of femur shaft fractures. LEVEL OF EVIDENCE: Diagnostic Level I. See Instructions for Authors for a complete description of levels of evidence.

Selective Patella Resurfacing in Contemporary Cruciate Retaining and Substituting Total Knee Arthroplasty: A Matched Cohort Analysis.

BACKGROUND: Leaving the patella unresurfaced in total knee arthroplasty (TKA) is increasing due to modern patella-friendly implants, awareness that complications are not uncommon with resurfacing, and knowledge that historical studies were scientifically confounded. This study examined the effect of selective patellar resurfacing on patient-reported outcome measures (PROMs) using modern implants and techniques in cohorts rigorously matched for demographics and osteoarthritis severity. METHODS: A total of 166 TKAs performed without patellar resurfacing were case-control matched to 166 TKAs with patella resurfacing. Case-control matching was based on demographics, American Society of Anesthesiology Physical Status, comorbidities, and osteoarthritis severity. No significant differences were observed between cohorts for demographics (P ≥ .347), comorbidities (P ≥ .443), or radiographic osteoarthritis severity (P ≥ .078). Radiographic alignment and prospectively collected PROMs were evaluated preoperatively and at latest clinical follow-up. RESULTS: Preoperatively, patellar tilt was less for the unresurfaced patella group (3 versus 4°, P = .003); however, postoperative patellar tilt was not different (3 versus 3°, P = .225). At a mean of 2.1 years follow-up (range, 1 to 7), University of California Los Angeles Activity Level was significantly higher for the unresurfaced patella group (6.3 versus 5.5, P = .002), but the mean group difference did not reach a minimal clinically important difference. There were no other significant differences in PROMs or reoperation rates between cohorts (P ≥ .135). CONCLUSION: In contemporary cruciate retaining and substituting TKA designs, not resurfacing the patella in select patients may achieve comparable PROMs and re-operation rates; and potentially greater activity level compared to patella resurfacing at early follow-up. LEVEL OF EVIDENCE: III.

Telehealth in Orthopedic Sports Medicine: A Survey Study on Patient Satisfaction and Experience.

Background: Telehealth has seen breakthroughs in many fields of medicine, but utilization remains limited in orthopedic sports medicine. The purpose of this investigation was to compare patient satisfaction, duration of care, and overall patient experiences with telehealth and in-person clinical visits for sports-related injuries. Methods: A cross-sectional survey study was conducted at an orthopedic sports medicine clinic during the peak of the COVID-19 pandemic between March and November 2020. Anonymous electronic surveys were used to record patient responses and statistical comparisons were drawn through two-sample t-tests. Results: A total of 175 patients (82 telehealth vs. 93 in-person) consented to participate in this investigation, and all were included in the final analysis. The overall composite satisfaction score, when compared between the two groups, did not differ (p = 0.63). Duration of care was significantly longer in the 93 patients who had in-person clinical visits as compared with the 82 patients who had telehealth visits (61/93: >31 min vs. 75/82: <30 min; p < 0.001). Finally, of the 82 patients who had telehealth, 3 respondents said they were "very unlikely" and "unlikely" to request another virtual clinical visit and/or recommend this mode of health care delivery to friends or family. Of the 93 patients had in-person clinical visits, only 15 respondents stated they were uninterested in telehealth under any circumstance. Conclusion: Most patients presenting to an orthopedic sports medicine clinic are open to telehealth, recognize its utility, and believe it to be just as comparable with in-person clinical visits. Level of Evidence: IV.

Health care disparities in surgical treatment of rotator cuff disease.

Background: Health care disparities have been well-documented in literature to affect care and recovery after surgery. Insurance type is regularly cited by orthopedic surgeons to play a role in the incongruences faced by patients in the perioperative period. Recent trends highlight an increased reluctance by some insurance companies to approve indicated surgery. Our primary objective was to assess insurance type and how it affects approval rates for rotator cuff débridement and rotator cuff repair. Methods: A retrospective review of 999 patients who underwent arthroscopic rotator cuff débridement or repair was conducted. Data abstraction included demographics, prior surgical or nonsurgical interventions, radiologic imaging, insurance type, and denial of insurance coverage. Patients were grouped by insurance type-Medicaid, Medicare, workers' compensation, and private insurance. Univariable and multivariable logistic regression models were developed to estimate odds ratios (ORs) for insurance type associated with the denial of insurance coverage. Results: Nine hundred ninety-seven patients were included in our final analysis. Those with private insurance were more likely to be non-Hispanic white (71%), whereas the proportion of Hispanics was highest among those with workers' compensation (27%) and Medicaid (20%). There were no significant differences by insurance type for prior nonsurgical interventions and radiologic imaging. For previous surgical interventions (13%), however, rates were higher for Medicaid (18%) and workers' compensation (17%) than those for Medicare (12%) and private insurance (9%) (P = .003). Compared with private insurance, the odds of insurance denial were significantly higher for those with Medicaid at 54% (OR: 7.91, 95% confidence interval: 5.27-11.88, P < .001) and workers' compensation at 19% (OR: 1.71, 95% confidence interval: 1.04-2.81, P = .04). Discussion: One in 2 patients with Medicaid coverage faces insurance denial compared with any other insurance type. Workers' compensation follows with the second highest rates. Almost half the Hispanic population are insured by either Medicaid or workers' compensation and may face barriers to care that can negatively impact outcomes and complication rates.

Surgically Treated Pectoralis Major Tears Impact the Play and Performance of National Football League Athletes.

Purpose: To evaluate the return-to-play rate and performance level changes in National Football League (NFL) athletes after a surgically treated pectoralis major muscle (PMM) tear. Methods: A descriptive epidemiologic study was conducted. All NFL players from 1933 to 2013 were reviewed for surgically treated PMM tears. Age at injury, height, weight, body mass index, date of injury, position played, draft selection, and total seasons played were recorded. Return to play was assessed for the entire cohort, as well as by position. Performance analysis before and after injury was also conducted for the entire cohort, as well as by position and draft selection. Data analysis was performed with the paired-samples t test, with P < .05 considered statistically significant. Results: Our review of 80 NFL seasons from 1933 to 2013 provided a total of 55 instances of PMM tears. All instances occurred between the time frame of 2004 and 2012. After exclusions, 24 instances unique to 24 NFL athletes were confirmed by 2 separate investigators and these athletes were included as our final study cohort. Of the 24 players identified to have a surgically repaired PMM tear, 20 (83%) returned to play. The mean return-to-play period was 302 ± 128 days. The mean difference in performance scores before versus after PMM injury was 171.33 and was statistically significant, with P = .0330. Conclusions: In this study, there was an 83% return-to-play rate after surgical repair of PMM tears. Although we found a statistically significant decrease in player performance after surgery, this difference was no longer seen after players were stratified by position type and draft selection. Level of Evidence: Level IV, therapeutic case series.

Is the timing of fixation associated with fracture-related infection among tibial plateau fracture patients with compartment syndrome? A multicenter retrospective cohort study of 729 patients.

BACKGROUND: Tibial plateau fractures with an ipsilateral compartment syndrome are a clinical challenge with limited guidance regarding the best time to perform open reduction and internal fixation (ORIF) relative to fasciotomy wound closure. This study aimed to determine if the risk of fracture-related infection (FRI) differs based on the timing of tibial plateau ORIF relative to closure of ipsilateral fasciotomy wounds. METHODS: A retrospective cohort study identified patients with tibial plateau fractures and an ipsilateral compartment syndrome treated with 4-compartment fasciotomy at 22 US trauma centers from 2009 to 2019. The primary outcome measure was FRI requiring operative debridement after ORIF. The ORIF timing relative to fasciotomy closure was categorized as ORIF before, at the same time as, or after fasciotomy closure. Bayesian hierarchical regression models with a neutral prior were used to determine the association between timing of ORIF and infection. The posterior probability of treatment benefit for ORIF was also determined for the three timings of ORIF relative to fasciotomy closure. RESULTS: Of the 729 patients who underwent ORIF of their tibial plateau fracture, 143 (19.6%) subsequently developed a FRI requiring operative treatment. Patients sustaining infections were: 21.0% of those with ORIF before (43 of 205), 15.9% at the same time as (37 of 232), and 21.6% after fasciotomy wound closure (63 of 292). ORIF at the same time as fasciotomy closure demonstrated a 91% probability of being superior to before closure (RR, 0.75; 95% CrI, 0.38 to 1.10). ORIF after fasciotomy closure had a lower likelihood (45%) of a superior outcome than before closure (RR, 1.02; 95% CrI; 0.64 to 1.39). CONCLUSION: Data from this multicenter cohort confirms previous reports of a high FRI risk in patients with a tibial plateau fracture and ipsilateral compartment syndrome. Our results suggest that ORIF at the time of fasciotomy closure has the highest probability of treatment benefit, but that infection was common with all three timings of ORIF in this difficult clinical situation.

The Long Head of the Biceps Myotendinous Junction Is Located 1.14 Centimeters Distal to the Proximal Border of the Pectoralis Major Tendon: An Anatomic Study.

Purpose: To describe the proportional anatomic relationship of the long head of the biceps tendon (LHBT) myotendinous junction (MTJ) to pectoralis major tendon (PMT) and to provide an up-to-date review of the current literature. Methods: Ten fresh frozen cadaveric specimens were used. A deltopectoral approach was used for exposure and anatomical location of the MTJ as well as the proximal and distal borders of the PMT were identified by 2 fellowship-trained shoulder and elbow surgeons. The longitudinal length of the PMT, the distance from the long head of the biceps (LHB) MTJ to the proximal border of the PMT (pMTJ), and the distance from the LHB MTJ to the distal border of the PMT (dMTJ) were recorded. The relationship between the pMTJ and the PMT length was then reported as a ratio. Results: The PMT was found to have a length of 5.16 ± 0.64 cm (4.1-6.1 cm). The pMTJ was 1.14 ± 0.52 cm (0.5-1.9 cm), and the dMTJ was 4.02 ± 0.91 cm (2.5-5.3 cm). The pMTJ/PMT ratio was 0.23 ± 0.11 (0.10-0.39). Conclusions: We found the average length of the PMT footprint to be 5.16 cm with the LHB MTJ beginning 1.14 cm distal to its proximal border. Clinical Relevance: It is important to understand the LHBT and its relationship to surgically relevant surrounding anatomy to allow for appropriate tensioning and improved patient outcomes in the treatment of LHBT shoulder pathology.

Risk factors for complications within 30 days of operatively fixed periprosthetic femur fractures.

Background: With a rising number of periprosthetic femur fractures (PPFFs) each year, the primary objective of our study was to quantify risk factors that predict complications following operative treatment of PPFFs. Methods: A retrospective cohort study of 231 patients with a periprosthetic femur fracture was conducted at an Academic, Level 1 Trauma Center. The main outcome measurement of interest was complications, as defined by the ACS-NSQIP, within 30 days of surgery. Results: 56 patients had 96 complications. Bivariate analyses revealed ASA score, preoperative ambulatory status, length of stay, discharge disposition, time from admission to surgery, length of surgery, perioperative change in hemoglobin, Charlson comorbidity index, cerebral vascular accident/transient ischemic attack, chronic obstructive pulmonary disease, diabetes mellitus, and receipt of a blood transfusion were associated with development of a complication (p < 0.1). Multivariate logistic regression showed length of stay (OR 1.11, 95% CI 1.03-1.19; p = 0.006), receipt of a blood transfusion (OR 2.48, 95% CI 1.14-5.42; p = 0.02), and diabetes mellitus (OR 2.17, 95% CI 1.03-4.56; p = 0.04) remained independently predictive of complication. Conclusions: Length of stay, receipt of a blood transfusion, and diabetes were associated with increased perioperative risk for developing a complication following operative treatment of periprosthetic femur fractures. Methods to decrease length of stay or transfusion rates may mitigate complication risk in these patients. Level of Evidence: Prognostic, Level III.

Delayed surgical repair of the deltoid following acromioplasty: a case report.

Currently, the literature contains few studies that describe any potential complications following arthroscopic acromioplasty. Because part of the anterior deltoid originates from the anterior acromion, there is a risk for violation and subsequent iatrogenic rupture or avulsion during this procedure. This type of injury can be a devastating problem for patients that may lead to poor function and debilitating pain. We present a patient with deltoid insufficiency following arthroscopic acromioplasty who elected to proceed with operative management with a planned arthroscopic evaluation of the shoulder followed by an open deltoid repair. At the final follow-up visit 2.5 years postoperatively, the patient reported improved pain from baseline and no residual disability and was able to perform most activities of daily living without difficulty. This case serves as an example of a surgical repair for a deltoid avulsion following arthroscopic acromioplasty. As there is still a lack of standard guidelines, our suture repair technique can be considered one method of treatment for this type of injury.

Utility of Plasma Protein Biomarkers and Mid-infrared Spectroscopy for Diagnosing Fracture-related Infections: A Pilot Study.

OBJECTIVES: To compare a large panel of plasma protein inflammatory biomarkers and mid-infrared (MIR) spectral patterns in patients with confirmed fracture-related infections (FRIs) with those in controls without infection. DESIGN: Prospective case-control study. SETTING: Academic, Level 1 trauma center. PATIENTS: Thirteen patients meeting confirmatory FRI criteria were matched to 13 controls based on age, time after surgery, and fracture region. INTERVENTION: Plasma levels of 49 proteins were measured using enzyme-linked immunosorbent assay techniques. Fourier transform infrared spectroscopy of dried films was used to obtain MIR spectra of plasma samples. MAIN OUTCOME MEASUREMENTS: The main outcome measurements included plasma protein levels and MIR spectra of samples. RESULTS: Multivariate analysis-based predictive model developed using enzyme-linked immunosorbent assay-based biomarkers had sensitivity, specificity, and accuracy of 69.2% ± 0.0%, 99.9% ± 1.0%, and 84.5% ± 0.6%, respectively, with platelet-derived growth factor-AB/BB, C-reactive protein, and MIG selected as the minimum number of variables explaining group differences ( P < 0.05). Sensitivity, specificity, and accuracy of the predictive model based on MIR spectra were 69.9% ± 6.2%, 71.9% ± 5.9%, and 70.9% ± 4.8%, respectively, with 6 wavenumbers as explanatory variables ( P < 0.05). CONCLUSIONS: This pilot study demonstrates the feasibility of using a select panel of plasma proteins and Fourier transform infrared spectroscopy to diagnose FRIs. Preliminary data suggest that the measurement of these select proteins and MIR spectra may be potential clinical tools to detect FRIs. Further investigation of these biomarkers in a larger cohort of patients is warranted. LEVEL OF EVIDENCE: Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Osteoarthritic Severity in Unresurfaced Patellae Does Not Adversely Affect Patient-reported Outcomes in Contemporary Primary TKA.

INTRODUCTION: The degree of osteoarthritis (OA) acceptable to leave in a native patella during unresurfaced total knee arthroplasty (TKA) remains unknown. This study's purpose was to examine the effect of patellofemoral OA severity on patient-reported outcome measures (PROMs) in primary TKAs performed without patellar resurfacing. METHODS: One hundred ninety-three primary TKAs performed without patellar resurfacing were retrospectively reviewed. Preoperative patellofemoral OA severity was graded on severity, marginal osteophytes, joint space narrowing, and chondral damage using accepted grading systems. Patellar tilt and tibiofemoral alignment were measured radiographically. PROMs were evaluated at a minimum of 1-year follow-up. RESULTS: In multivariate regression, preoperative lateral patella Kellgren-Lawrence grade ≥2 was associated with superior change in Knee Society Score pain with level walking, higher absolute change in Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (P ≤ 0.029), and knees ?always feeling normal" (odds ratio [OR] 3.12; P = 0.005). Osteoarthritis Research Society International atlas grades and Outerbridge classification scores did not significantly influence PROMs. DISCUSSION: Worse preoperative OA severity in the lateral patellar facet, graded with the Kellgren-Lawrence system, predicted superior knee-specific PROMs in patients with unresurfaced patellae after contemporary TKA. This observation supports the clinical finding that patients with more severe OA have optimized patient outcomes and highlights the minimal contribution of patella OA to knee function after primary TKA.

Assaults in schools: Findings using a national data base.

BACKGROUND: Assaults can occur at schools/educational facilities involving students, teachers and other school employees. It was the purpose of this study to correlate injury patterns with patient demographics in school assault victims. Understanding injury patterns with their associated demographics will not only be useful for health care providers but can also assist in proposing prevention strategies for both students and school employees. METHODS: Emergency department data from the National Electronic Injury Surveillance System All Injury Program data for the years 2005 through 2015 were used in this study. Statistical analyses were performed with SUDAAN software to account for the weighted, stratified nature of the data. RESULTS: There were an estimated 852,822 ED visits for school assaults. The median age was 13.8 years with 81.3% between 5 and 19 years old; 64.4% were male. After age 4, the number of females proportionately increased with increasing age. The most common diagnosis was a contusion/abrasion (38.6%). The injuries occurred in the head/neck (63.9%), upper extremity (19.0%), upper trunk (6.6%), lower trunk (5.5%), and lower extremity (4.9%). Firearm violence accounted for 0.1% of the assaults. Human bites occurred in 3.7%. Sexual assault was rare and proportionally the highest in those ≤4 years of age. Internal organ injuries were more common in females (13.1% vs 3.55) and for those admitted to the hospital (29.9% vs 19.9%). The incidence of ED visits for school assault decreased 50% from 2005 to 2015. CONCLUSIONS: This study analyzed ED visits due to assaults occurring in schools. Firearm violence accounted for only 0.1% of the injuries, in contrast to media coverage regarding school assaults. The most common injury location was the head/neck (63.9%) and the most common diagnosis was a contusion/abrasion. This data can also serve as a baseline for further studies and the impact of potential reduction strategies.

Transitioning from the Posterior Approach to the Direct Anterior Approach for Total Hip Arthroplasty.

Purpose: Total hip arthroplasty (THA) using the direct anterior approach (DAA) is known to have a learning curve. The purpose of this study was to review cases where surgery was performed by an arthroplasty surgeon transitioning from the posterior approach (PA) to the DAA. We hypothesized similar complication rates and improvements in surgical duration over time. Materials and Methods: A review of 2,452 consecutive primary THAs was conducted. Surgical duration, length of stay (LOS), surgical complications, decrease in postoperative day (POD) 1 hemoglobin, transfusion rates, POD 0 and POD 1 pain scores, incision length, leg length discrepancy (LLD), and radiographic cup position were recorded. Results: No differences in surgical duration were observed after the first 50 DAA cases. A shorter LOS was observed for the DAA, and statistical difference was appreciated after the first 100 DAA cases. There were no differences in periprosthetic fractures. A higher rate of infections and hip dislocations were observed with the PA. The PA showed an association with higher transfusion rates without significant difference in POD 1 decrease in hemoglobin over the first 100 DAA cases. Similar POD 0 and POD 1 pain scores with a smaller incision were observed for the first 100 DAA cases. The DAA cohort showed less variation in cup inclination, version, and LLD. Conclusion: DAA is safe and non-inferior in terms of reduced LOS, smaller incision, and less variation in cup position. Fifty DAA cases was noted to be the learning curve required before no differences in duration between approaches were observed.

Machine Learning Algorithms Identify Optimal Sagittal Component Position in Total Knee Arthroplasty.

BACKGROUND: Advanced technologies, like robotics, provide enhanced precision for implanting total knee arthroplasty (TKA) components; however, the optimal targets for implant position specifically in the sagittal plane do not exist. This study identified sagittal implant position which may predict improved outcomes using machine learning algorithms. METHODS: A retrospective review of 1091 consecutive TKAs was performed. All TKAs were posterior cruciate ligament retaining or sacrificing with an anterior-lip (49.4%) or conforming bearing (50.6%) and performed with modern perioperative protocols. Preoperative and postoperative tibial slope and postoperative femoral component flexion were measured with standardized radiographic protocols. Analysis groups were categorized by satisfaction scores and the Knee Society Score question 'does this knee feel normal to you?' Machine learning algorithms were used to identify optimal sagittal alignment zones that predict superior satisfaction and knees "always feeling normal" scores. RESULTS: Mean age and median body mass index were 66 years and 34 kg/m2, respectively, with 67% being female. The machine learning model predicted an increased likelihood of being "satisfied or very satisfied" and a knee "always feeling normal" with a change in tibial slope closer to native (-2 to +2°) and femoral component flexion 0 to +7°. Worse outcomes were predicted with any femoral component extension, femoral component flexion beyond +10°, and adding or removing >5° of native tibial slope. CONCLUSION: Superior patient-reported outcomes were predicted with approximating native tibial slope and incorporating some femoral component flexion. Deviation from native tibial slope and excessive femoral flexion or any femoral component extension were predictive of worse outcomes. LEVEL OF EVIDENCE: Therapeutic level III.

Efficacy of a single, image-guided corticosteroid injection for glenohumeral arthritis.

BACKGROUND: Limited data are available on the efficacy of cortisone injections for glenohumeral osteoarthritis (GHOA). The amount and longevity of pain relief provided by a single cortisone injection are unclear. Additionally, it remains uncertain how the severity of radiographic GHOA and patient-reported function and pain levels impact the efficacy of an injection. Therefore, we sought to describe the relief provided by a single, image-guided glenohumeral injection in patients with GHOA. We hypothesized that patients with more severe radiographic GHOA and poorer baseline shoulder function would require earlier secondary intervention. METHODS: Patients with symptomatic GHOA who elected to receive a corticosteroid injection for pain relief were prospectively enrolled. A phone interview was conducted to record the baseline Oxford Shoulder Score (OSS) and visual analog scale (VAS) score prior to the injection, as well as the OSS and VAS score at months 1, 2, 3, 4, 6, 9, and 12 after the injection. The endpoint of the study occurred when patients required a second injection, progressed to surgery, or reached month 12. Patients were grouped by their respective baseline OSS (mild vs. moderate or severe) and Samilson-Prieto radiographic classification (mild, moderate, or severe) for analysis. RESULTS: We analyzed 30 shoulders (29 patients). Of the patients, 52% were men. The average age was 66.1 years. No significant difference in overall survival (defined as no additional intervention) was seen between groups based on either the OSS or Samilson-Prieto grade. Additionally, the OSS and VAS score at each follow-up were compared with baseline values. For the entire cohort, a clinically significant difference was seen between baseline and months 1-4 for the OSS and between baseline and months 1-4, 6, 9, and 12 for the VAS score. DISCUSSION: This study aimed to determine the efficacy of corticosteroid injections for GHOA. There were no differences in the need for secondary intervention in this population based on the severity of either the OSS or the Samilson-Prieto radiographic classification. However, patients with more severe shoulder dysfunction based on the OSS did experience statistically significantly greater symptomatic relief than patients with milder dysfunction. Additionally, following a single injection, patients in this cohort experienced statistically and clinically relevant improvements in shoulder function and pain up to 4 months after injection.