Intra-articular steroid injection at the time of knee arthroscopy increases risk of post-operative infection.

PURPOSE: To evaluate the risk of post-operative infection after intra-articular steroid injection at the time of knee arthroscopy at a single institution high-volume sports medicine practice. METHODS: The electronic medical record at a single institution was queried for all patients who underwent knee arthroscopy from 2011 to 2019. Patients were included if they underwent more simple arthroscopic procedures: diagnostic arthroscopy, meniscectomy, loose body removal, synovectomy, or microfracture. Patients were excluded if they underwent more complex procedures, such as ligament reconstruction, meniscus repair, or any open procedures. These patients' medical records were then queried for current procedural terminology and international classification of disease codes indicating post-operative infection. Individual chart review was performed on this group of patients to determine if a true postoperative infection occurred within 6 months of the index arthroscopy. Patients were then categorized into "intra-operative steroid injection" versus "no steroid" based on each surgeon's preferred intra-operative analgesic injection cocktail. RESULTS: A total of 6889 patients were identified, including 2416 (35.1%) who were given intra-articular steroid at the time of knee arthroscopy. Post-operative infection occurred in 10 patients (0.15%) at a median of 18 days (range 9-42 days), 7 who received intra-operative steroid injection (0.29%) and 3 who did not (0.067%), p = 0.040. The relative risk of infection for those who received intra-operative steroid injection was 4.32 times higher than those who did not, with a number needed to harm of 448. There were no significant differences in age, body mass index, smoking status, or the prevalence of diabetes between those who got infected and those who did not. CONCLUSIONS: Knee infection following arthroscopic surgery is rare. Intra-operative steroid injection during arthroscopic knee surgery is associated with a 4.3-fold increased risk of subsequent knee infection. While the overall risk remains low, the use of intra-operative steroids is expected to result in one additional knee infection for every 448 arthroscopic procedures performed. LEVEL OF EVIDENCE: IV.

Ultrasound Cross-Sectional Area in Median Nerve Axonal Loss and Demyelination in Carpal Tunnel Syndrome.

Introduction: Ultrasound is an effective diagnostic tool for carpal tunnel syndrome (CTS). However, it is unclear how ultrasound correlates with axonal loss and/or demyelination on electrodiagnostic studies (EDS). The objective of this study is to determine whether ultrasound cross-sectional area (CSA) of the median nerve varies between patients with axonal loss or demyelination. Methods: A retrospective review was completed of patients who presented to an orthopaedic hand clinic with numbness/paresthesias over a 6-year period. Demographics, CTS symptoms scale 6 (CTS-6) scores, Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) scores, EDS results, and ultrasound results were collected. Median neuropathies were graded as normal, demyelination, or axonal loss using EDS reports. The data were analyzed with chi-square and t-tests. Results: In all, 383 hands were included (92 axonal loss, 182 demyelination only, and 108 neither). The average patient age was 52.2 and the average body mass index (BMI) was 31.7. The group consisted of 70.7% females, and 23.2% had diabetes. Patients with either axonal loss or demyelination had larger CSA and higher CTS-6 and BCTQ scores than patients with negative EDS. Patients with axonal loss also had larger CSA and higher CTS-6 and BCTQ scores than patients with demyelination only. The rates of positive ultrasound results between axonal loss and demyelination groups did not differ until the ultrasound cutoff was increased from 10 to 12 mm2. Conclusion: Rates of positive ultrasound results (CSA ≥ 10 mm2) do not differ between wrists with axonal loss or demyelination alone. Therefore, the character of carpal tunnel neuropathy does not affect ultrasound's diagnostic ability. Additionally, CSA increases as wrists develop axonal loss, and an increased ultrasound cutoff of 12 mm2 is correlated with this pathology.

Ultrasound Cross-Sectional Area of the Median Nerve Is Not a Predictor of Patient Reported Outcomes After Carpal Tunnel Release.

BACKGROUND: The purpose of this study was to evaluate the relationship between cross sectional area (CSA) of the median nerve on ultrasound (US) with pre- and postoperative Boston Carpal Tunnel Questionnaire (BCTQ) scores. We hypothesize that there is a positive correlation between CSA and the ΔBCTQ after carpal tunnel release (CTR). METHODS: This was a single center study. During a 6-year period (2014-2020), CSA of the median nerve on US and BCTQ scores were collected prospectively for patients presenting with the chief complaint of numbness and tingling in the upper extremity. Patients who underwent CTR and presented for their 6-week follow-up had repeat measurements of the CSA and BCTQ. These patients were included in this study. Patients were then divided into ultrasound positive (CSA ≥ 10) and ultrasound negative (CSA < 10) groups. These groups were compared on the basis of demographics, preoperative BCTQ scores, postoperative BCTQ scores, and 6-week ΔBCTQ score. RESULTS: US-positive and-negative groups did not differ significantly in their preoperative BCTQ, postoperative BCTQ, or ΔBCTQ scores. Both groups did, however, experience significant improvement when comparing preoperative to postoperative BCTQ scores within their respective US group. CONCLUSION: Regardless of the preoperative CSA of the median nerve, patients who underwent CTR experienced a significant improvement in their BCTQ results. US-positive patients experienced no greater improvement than US-negative patients. These results would suggest that US is not a good predictor of subjective surgical outcome measures such as the BCTQ.

Computed Tomography-Based Humeral Templating for Uncemented Elbow Arthroplasty.

BACKGROUND: Intramedullary (IM) screw insertion into the distal humerus provides fixation for a novel, uncemented elbow arthroplasty. A multitude of screw sizes is required to accommodate variable humeral morphology. The goal of this study was to use computed tomography (CT) for IM screw sizing and to validate this templating by inserting screws into three-dimensionally (3D) printed models. METHODS: Computed tomography humerus scans for 30 patients were reformatted in the plane of the distal IM canal. Screw size was templated by measuring the canal diameter at 3 locations corresponding to the lengths of the screws being tested. Interrater and intrarater reliabilities of the measurements were assessed. Three-dimensional models of 5 humeri were printed, and IM screws were placed to achieve a secure endosteal fit. RESULTS: We identified combinations of body components and IM screw length and diameter for all patients to seat this uncemented elbow arthroplasty. The measurements and screw width determinations were reliable. Canal diameter correlated with age but was unrelated to sex. Screws were inserted into five 3D-printed models which matched the templates and demonstrated mechanical and radiographic evidence of secure fit. CONCLUSIONS: This study characterizes distal humerus anatomy in the context of IM screw fixation. Humerus CT scans of 30 patients were able to be templated, and validation via implantation of IM screws into 3D models was successful. Computed tomography templating will allow surgeons to predict the optimal screw size prior to implantation. A broad range of screw lengths and diameters is critical for implantation of this novel elbow arthroplasty.

Mega Nerves: Factors Associated with Large Median Nerves on Ultrasound of the Carpal Tunnel.

Although increased cross-sectional area of the median nerve on ultrasound has been associated with carpal tunnel syndrome, there has been little research examining outlier cases with exceedingly large nerves. The purpose of this study was to identify factors associated with these "mega" nerves, and to determine whether these nerves carry with them increased severity of disease. Methods: Patients who presented to clinic with upper extremity paresthesias over a 4-year period were included in this study. Two groups were created: mega nerves (cross-sectional area >2 SD above average), and nonmega nerves. Statistical analysis was performed to compare demographics, symptom scores, and nerve conduction studies (NCS). Significant variables were then compared between patients with mega nerves and those with ultrasound positive nerves (≥10 mm2), which did not reach mega size (normal nerves were excluded). Results: The cohort included 425 median nerves with 25 mega nerves. The groups differed significantly in diabetes status, body mass index (BMI), Boston Carpal Tunnel Questionnaire (BCTQ) Symptom Severity Scale scores, and NCS results. When compared only with ultrasound positive but nonmega nerves, mega nerves were still associated with diabetes, higher BMI, and worse NCS results. Conclusions: Diabetes, BMI, NCS results, and BCTQ Symptom Severity Scale scores are associated with mega nerves. However, BCTQ scores do not differ between mega nerves and other ultrasound positive nerves. In patients with obesity or diabetes, outlier ultrasound measurements may not correlate with worsened clinical symptoms, even in the setting of more significantly altered NCS results.

Localization of the Median Nerve and Flexor Pollicis Longus at the Carpal Tunnel Inlet in Patients With and Without Carpal Tunnel Syndrome Using Ultrasound.

BACKGROUND: Current illustrations of the carpal tunnel vary greatly. The relative positions of the components such as the median nerve and flexor pollicis longus (FPL) tendon seem often arbitrarily chosen. The purpose of this study was to determine the locations of the median nerve and FPL in the carpal tunnel using ultrasound (US) and to determine whether the position of the median nerve changes in carpal tunnel syndrome (CTS). METHOD: Patients with and without CTS underwent US examination of the wrist. A 4 × 10 grid was fitted to each saved cross-sectional image. The center points of the median nerve and FPL were identified, and their horizontal and vertical coordinates were recorded. RESULTS: The median nerve was identified in 115 wrists (average x = 0.70, y = 0.82), and FPL was identified in 90 wrists (average x = 0.86, y = 0.59). A scatter plot was created by stacking all US images to demonstrate the average positions of the median nerve and FPL. There were 97 wrists without CTS (No CTS) and 17 wrists with CTS. There was a significant difference in the vertical position of the median nerve between No CTS and CTS wrists (P = .0006). CONCLUSIONS: The locations of the median nerve and FPL within the carpal tunnel were determined using US of 115 wrists, and a heat map was created to illustrate these locations. The median nerve was found to be more superficial in the setting of CTS.

Impact of oxidation catalysts on exhaust NO2/NOx ratio from lean-burn natural gas engines.

Oxides of nitrogen (NOx) emitted from internal combustion engines are composed primarily of nitric oxide (NO) and nitrogen dioxide (NO2). Exhaust from most combustion sources contains NOx composed primarily of NO. There are two important scenarios specific to lean-burn natural gas engines in which the NO2/NOx ratio can be significant: (1) when the engine is operated at ultralean conditions and (2) when an oxidation catalyst is used. Large NO2/NOx ratios may result in additional uncertainty in NOx emissions measurements because the most common technique (chemiluminescence) was developed for low NO2/NOx ratios. In this work, scenarios are explored in which the NO2/NOx ratio can be large. Additionally, three NOx measurement approaches are compared for exhaust with various NO2/NOx ratios. The three measurement approaches are chemiluminescence, chemical cell, and Fourier-transform infrared spectroscopy. A portable analyzer with chemical cell technology was found to be the most accurate for measuring exhaust NOx with large NO2/NOx ratios.

What are the Rates, Reasons, and Risk Factors of 90-day Hospital Readmission After Lumbar Discectomy?: An Institutional Experience.

STUDY DESIGN: This is a retrospective cohort study. OBJECTIVE: To report the rate, reasons, and risk factors for 90-day readmissions after lumbar discectomy at an academic medical center. SUMMARY OF BACKGROUND DATA: Several studies have reported complications and readmissions after spine surgery; however, only one previous study has focused specifically on lumbar discectomy. As the patient profile and morbidity of various spine procedures is different, focus on procedure-specific complications and readmissions will be beneficial. MATERIALS AND METHODS: Patients who underwent lumbar discectomy for unrelieved symptoms of prolapsed intervertebral disk and had at least 90 days of follow-up at an academic institution (2013-2014) were included. Retrospective review of electronic medical record was performed to record demographic and clinical profile of patients. Details of lumbar discectomy, index hospital stay, discharge disposition, hospital readmission within 90 days, reason for readmission and treatment given have been reported. Risk factors for hospital readmission were analyzed by multivariate logistic regression analysis. RESULTS: A total of 356 patients with a mean age of 45.0±13.8 years were included. The 90-day readmission rate was 5.3% (19/360) of which two-third patients were admitted within 30 days giving a 30-day readmission rate of 3.7% (13/356). The top 2 primary reasons for readmission included back and/or leg pain, numbness, or tingling (42.9%), and persistent cerebrospinal fluid leak or seroma (25.0%). On adjusted analysis, risk factors associated with higher risk of readmission included incidental durotomy [odds ratio (OR), 26.2; 95% confidence interval (CI), 5.3-129.9] and discharge to skilled nursing facility/inpatient rehabilitation (OR, 25.2; 95% CI, 2.7-235.2). Increasing age was a negative predictor of readmission (OR, 0.95; 95% CI, 0.91-0.99). CONCLUSIONS: Incidental durotomy, younger age, and discharge to nursing facility were associated with higher risk of 90-day hospital readmission after lumbar discectomy. As compared with extensive spine procedures, patient comorbidity burden may not be as significant in predicting readmission after this relatively less invasive procedure.