Comparison of Postoperative Outcomes of Patients Undergoing Total Hip and Total Knee Arthroplasty Following a Diagnosis of Dementia: A TriNetX Database Study

Background

As life expectancy improves for patients with dementia, the demand for mobility-improving surgeries such as total joint arthroplasty (TJA) will increase. There is little research on patients with dementia undergoing TJA, although dementia has been shown to be a risk factor for complications. The purpose of this study is to compare postoperative outcomes of patients with dementia undergoing TJA at 90 days, 2 years, and 5 years.

Methods

The TriNetX database was retrospectively queried for all patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA). Patients were divided into cohorts by preoperative diagnosis of dementia and propensity score matched. The following outcomes were evaluated between groups at 90 days, 2 years, and 5 years postoperatively: revision, resection arthroplasty, closed reduction (THA only), femur fracture plating, and prosthetic joint infection. Readmission and manipulation under anesthesia (TKA only) were evaluated at 90 days postoperatively. Univariate and multivariate analyses were performed.

Results

After matching, there were no differences in demographics or comorbidities between groups. TKA (odds ratio [OR] = 1.75, 95% confidence interval [CI] 1.42-2.15, P < .001) and THA (OR = 2.17, 95% CI 1.92-2.45, P < .001) patients with dementia were more likely to be readmitted than patients without dementia. At 2 years (OR = 2.07, 95% CI 1.14-3.77, P = .015) and 5 years (OR = 2.14, 95% CI 1.32-3.48, P = .002) postoperatively, THA patients with dementia were more likely to have proximal femur fracture plating than patients without dementia.

Conclusions

Patients undergoing THA with dementia had worse outcomes than patients undergoing THA without dementia and TKA with dementia. The overall rate of complications was low, and a diagnosis of dementia should not be an absolute contraindication to proceeding with TJA.

Managing an epidemic within a pandemic: orthopedic opioid prescribing trends during COVID-19

INTRODUCTION

In response to the opioid epidemic, a multitude of policy and clinical-guideline based interventions were launched to combat physician overprescribing. However, the sudden rise of the Covid-19 pandemic disrupted all aspects of healthcare delivery. The purpose of this study was to evaluate how opioid prescribing patterns changed during the Covid-19 pandemic within a large multispecialty orthopedic practice.

MATERIALS AND METHODS

A retrospective review of 1,048,559 patient encounters from January 1, 2015 to December 31, 2022 at a single orthopedic practice was performed. Primary outcomes were the percent of encounters with opioids prescribed and total morphine milligram equivalents (MMEs) per opioid prescription. Differences in outcomes were assessed by calendar year. Encounters were then divided into two groups: pre-Covid (1/1/2019-2/29/2020) and Covid (3/1/2020-12/31/2022). Univariate analyses were used to evaluate differences in diagnoses and outcomes between periods. Multivariate analysis was performed to assess changes in outcomes during Covid after controlling for differences in diagnoses. Statistical significance was assessed at p < 0.05.

RESULTS

The percentage of encounters with opioids prescribed decreased from a high of 4.0% in 2015 to a low of 1.6% in 2021 and 2022 (p < 0.001). MMEs per prescription decreased from 283.6 ± 213.2 in 2015 to a low of 138.6 ± 100.4 in 2019 (p < 0.001). After adjusting for diagnoses, no significant differences in either opioid prescribing rates (post-COVID OR = 0.997, p = 0.893) or MMEs (post-COVID β = 2.726, p = 0.206) were observed between the pre- and post-COVID periods.

CONCLUSION

During the Covid-19 pandemic opioid prescribing levels remained below historical averages. While continued efforts are needed to minimize opioid overprescribing, it appears that the significant progress made toward this goal was not lost during the pandemic era.

Social vulnerability adversely affects emergency-department utilization but not patient-reported outcomes after total joint arthroplasty

INTRODUCTION

Multiple studies demonstrate social deprivation is associated with inferior outcomes after total hip (THA) and total knee (TKA) arthroplasty; its effect on patient-reported outcomes is debated. The primary objective of this study evaluated the relationship between social vulnerability and the PROMIS-PF measure in patients undergoing THA and TKA. A secondary aim compared social vulnerability between patients who required increased resource utilization or experienced complications and those who didn't.

MATERIALS AND METHODS

A retrospective review of 537 patients from March 2020 to February 2022 was performed. The Centers for Disease Control Social Vulnerability Index (SVI) were used to quantify socioeconomic disadvantage. The cohort was split into THA and TKA populations; univariate and multivariate analyses were performed to evaluate primary and secondary outcomes. Statistical significance was assessed at p < 0.05.

RESULTS

48.6% of patients achieved PROMIS-PF MCID at 1-year postoperatively. Higher levels of overall social vulnerability (0.40 vs. 0.28, p = 0.03) were observed in TKA patients returning to the ED within 90-days of discharge. Increased overall SVI (OR = 9.18, p = 0.027) and household characteristics SVI (OR = 9.57, p = 0.015) were independent risk factors for 90-day ED returns after TKA. In THA patients, increased vulnerability in the household type and transportation dimension was observed in patients requiring 90-day ED returns (0.51 vs. 0.37, p = 0.04).

CONCLUSION

Despite an increased risk for 90-day ED returns, patients with increased social vulnerability still obtain good 1-year functional outcomes. Initiatives seeking to mitigate the effect of social deprivation on TJA outcomes should aim to provide safe alternatives to ED care during early recovery.

The association between losartan potassium prescription and postoperative outcomes following total knee arthroplasty: A TriNetX analysis

BACKGROUND

Total knee arthroplasty (TKA) is a common surgical procedure performed to alleviate pain and improve functional outcomes in patients with knee osteoarthritis and rheumatoid arthritis who have failed conservative treatments. Arthrofibrosis has been extensively studied due to its negative impact on TKA outcomes. Losartan, an angiotensin receptor blocker (ARB), has the potential to improve TKA outcomes by inhibiting TGF-β and decreasing fibrosis. This study aims to analyze a large-scale, real-world healthcare database to investigate the association between losartan potassium prescription and postoperative outcomes such as readmissions, ED visits, and the need for MUA or revision TKA.

HYPOTHESIS

Based on previous literature and the nature of ARBs, it is expected that the addition of losartan will aid in better outcomes for patients following a primary TKA.

PATIENTS AND METHODS

In this retrospective observational study, the TriNetX Research Network (TriNetX) database was queried as of June 21, 2023. All patients who underwent a primary total knee arthroplasty (TKA) prior to June 21, 2022 were included. Patients were then divided into two cohorts by whether they had an active losartan potassium prescription within the year prior to their surgery to within 90days postoperatively. Patients were then propensity-matched to eliminate differences in demographics and comorbidities.

RESULTS

Losartan TKA patients were 1.18 [OR: 0.85 (95% CI: 0.79-0.90), p<0.001] times less likely to be readmitted within 90days and were 1.15 (OR: 0.87 (95% CI: 0.79-0.96); p=0.009) times less likely to undergo a manipulation under anesthesia (MUA) within the 1-year postoperative period. There were no statistically significant differences in rates of emergency department (ED) visits at 90days postoperatively or revision TKAs at 1year postoperatively.

DISCUSSION

In conclusion, patients with an active losartan prescription prior to TKA had a significantly lower likelihood of readmission within 90days and a lower likelihood of undergoing MUA within the 1-year postoperative period compared to patients not taking losartan. This presents an opportunity for further clinical investigation to explore the value of losartan in TKA.

LEVEL OF EVIDENCE

III; an observational cohort study.

Natural Background and the Anthropogenic Enrichment of Mercury in the Southern Florida Environment: A Review with a Discussion on Public Health

Mercury (Hg) is a toxic metal that is easily released into the atmosphere as a gas or a particulate. Since Hg has serious health impacts based on human exposure, it is a major concern where it accumulates. Southern Florida is a region of high Hg deposition in the United States. It has entered the southern Florida environment for over 56 MY. For the past 3000 to 8000 years, Hg has accumulated in the Everglades peatlands, where approximately 42.3 metric tons of Hg was deposited. The pre-industrial source of mercury that was deposited into the Everglades was from the atmosphere, consisting of combined Saharan dust and marine evasion. Drainage and the development of the Everglades for agriculture, and other mixed land uses have caused a 65.7% reduction in the quantity of peat, therefore releasing approximately 28 metric tons of Hg into the southern Florida environment over a period of approximately 133 years. Both natural and man-made fires have facilitated the Hg release. The current range in mercury release into the southern Florida environment lies between 994.9 and 1249 kg/yr. The largest source of Hg currently entering the Florida environment is from combined atmospheric sources, including Saharan dust, aerosols, sea spray, and ocean flux/evasion at 257.1-514.2 kg/yr. The remobilization of Hg from the Everglades peatlands and fires is approximately 215 kg/yr. Other large contributors include waste to energy incinerators (204.1 kg/yr), medical waste and crematory incinerators (159.7+ kg/yr), and cement plant stack discharge (150.6 kg/yr). Minor emissions include fuel emissions from motorized vehicles, gas emissions from landfills, asphalt plants, and possible others. No data are available on controlled fires in the Everglades in sugar farming, which is lumped with the overall peatland loss of Hg to the environment. Hg has impacted wildlife in southern Florida with recorded excess concentrations in fish, birds, and apex predators. This bioaccumulation of Hg in animals led to the adoption of regulations (total maximum loads) to reduce the impacts on wildlife and warnings were given to consumers to avoid the consumption of fish that are considered to be contaminated. The deposition of atmospheric Hg in southern Florida has not been studied sufficiently to ascertain where it has had the greatest impacts. Hg has been found to accumulate on willow tree leaves in a natural environment in one recent study. No significant studies of the potential impacts on human health have been conducted in southern Florida, which should be started based on the high rates of Hg fallout in rainfall and known recycling for organic sediments containing high concentrations of Hg.

Outpatient physical therapy bundled payment models are feasible for total hip arthroplasty patients: an evaluation of utilization, cost and outcomes

BACKGROUND

Various episode-of-care bundled payment models for patients undergoing total joint arthroplasty have been implemented. However, participation in bundled payment programs has dropped given the challenges of meeting continually lower target prices. The purpose of our study is to investigate the cost of outpatient physical therapy (PT) and the potential for stand-alone outpatient PT bundled payments for patients undergoing total hip arthroplasty (THA).

METHODS

A retrospective review of 501 patients who underwent primary unilateral THA from November 2017 to February 2020 was performed. All patients included in this study received postoperative PT care at a single hospital-affiliated PT practice. Patients above the 75th percentile of therapy visits were then classified as high-PT utilizers and compared with the rest of the population using univariate statistics. Stepwise multivariate logistic regression was used to assess the predictors of high therapy utilization.

RESULTS

Patients averaged 65 ± 10 years of age and a BMI of 29 ± 5 kg/m². Overall, 80% of patients were white and 53% were female. The average patient had 11 ± 8 total therapy sessions in 42 days: one initial evaluation, one re-evaluation and 9 standard sessions. High-PT utilizers incurred estimated average costs of $1934 ± 431 per patient, compared to $783 ± 432 (P < 0.001) in the rest of the population. Further, no significant differences in 90-day outcomes including lower extremity functional scale scores, emergency department returns, readmissions, or returns to the operating room were observed between high utilizers and the rest of the population (all P > 0.08). In the multivariate analysis, women (OR = 1.68, P = 0.017) and those with sleep apnea (OR = 2.02, P = 0.012) were nearly twice as likely to be high utilizers, while white patients were 42% less likely to be high utilizers than patients of other races (OR = 0.58, P = 0.028).

CONCLUSIONS

Outpatient PT utilization is highly variable in patients undergoing THA. However, despite using more services and incurring increased cost, patients in the top quartile of utilization experienced similar outcomes to the rest of the population. If outpatient therapy bundles are to be developed, 16 visits appear to be a reasonable target for pricing, given this provides adequate coverage for 75% of THA patients.

The effects of hypoalbuminemia in obese patients undergoing total joint arthroplasty

INTRODUCTION

Total joint arthroplasty (TJA) is a highly effective surgery. However, poor nutritional status has been associated with worse outcomes. In orthopedics, nutrition status is commonly evaluated using serum albumin. When albumin levels fall below 3.0 g/dL, wound healing ability becomes impaired. Typically, malnutrition is associated with low BMI, but malnourished patients can also be obese. The goals of this study were to investigate the relationship between malnourishment represented through albumin levels of obese patients and likelihood of postoperative complications.

METHODS

A retrospective review of patients undergoing primary TJA from 2016 to 2020 in the American College of Surgeons National Surgical Quality Improvement Program national database was performed. Patients with an albumin of < 3.5 g/dL were considered to have hypoalbuminemia and those with ≥ 3.5 g/dL were considered normal albumin. Univariate analysis was used to determine demographic and comorbidity differences between those with and without hypoalbuminemia. Outcomes of interest included length of stay, resource utilization, discharge disposition, and unplanned readmissions. Multivariate logistic regression examined albumin as a predictor of increased resource utilization and complications after controlling for possible confounding variables.

RESULTS

Of the 79,784 patients, 4.96% of patients had low albumin. Those with hypoalbuminemia were nearly 1.5 years older than those with normal albumin, were more likely to be black, female, and had an overall increased comorbidity burden as shown by percent of patients with ASA > 3 (all p < 0.001). After risk adjustment, those with hypoalbuminemia and a BMI of 35 + had greater risk of complications and increased resource utilization.

CONCLUSION

Our results demonstrated the prevalence of malnutrition increases as a patient's BMI increases. Further, hypoalbuminemia was associated with increased resource utilization and increased complication rates in all obese patients. We suggest screening albumin levels in obese patients preoperatively to give surgeons the best opportunity to optimize patient nutrition before undergoing surgery.

Adductor Canal Blocks Are Not Associated With Improved Early Postoperative Outcomes in Patients Undergoing Total Knee Arthroplasty

Background: As length of stay after total knee arthroplasty (TKA) continues to shorten, interventions that may reduce early postoperative pain and complications must be studied. Peripheral nerve block is being explored as a potential means of improving pain management. The purpose of this study was to evaluate the impact of adductor canal block (ACB) on postoperative outcomes for patients undergoing TKA. Methods: We conducted a retrospective review of 565 patients who received unilateral TKA under spinal anesthesia with a periarticular anesthetic injection. Patients were divided by ACB status. Univariate comparisons and multivariate regression were used to compare outcomes for patients receiving ACBs vs those who did not. Results: Of the 565 patients, 167 received an ACB, and 398 did not. Patients who received an ACB were less likely to require nausea medication during the immediate postoperative period. Length of stay, narcotic consumption, rate of discharge to home, postanesthesia care unit recovery time, urinary retention, ability to complete physical therapy, and 30-day readmission rate did not differ significantly between groups. After risk adjustment, the only significant finding was decreased likelihood of nausea in patients receiving an ACB. Conclusion: ACBs appear to have little to no significant impact on early clinical outcomes in patients having TKA under spinal anesthesia with a periarticular anesthetic injection. Further study of larger patient cohorts is required to validate these findings.

Racial Disparities in Outcomes of Total Joint Arthroplasty at a Single Institution: Have We Made Progress?

Background

Health disparities disproportionately affect minority groups across the United States with respect to care access, quality, and outcomes. The aim of this study is to examine existing disparities between white and African American (AA) patients regarding postoperative outcomes following total joint arthroplasty and provide insight into disparity trends over a 9-year period.

Methods

A retrospective review of 16,779 total joint arthroplasty patients at a single institution between January 2013 and December 2021 was performed. Patients were grouped by race as AA or white. Outcomes of interest included length of stay (LOS), home discharge, 30-day emergency department return, and 30-day readmission. Univariate statistics and multivariate regressions were utilized to analyze results.

Results

Significant improvements in LOS and rates of home discharge occurred for both white and AA patients at our institution over a 9-year period, while rates of 30-day emergency department returns and readmissions demonstrated a downward but non-statistically significant trend. Despite these trends, AA patients continued to experience longer lengths of stay, less likelihood of 0- or 1-day LOS, and higher risk of nonhome discharge for most years examined. However, after controlling for demographic and comorbidity differences, the differences between groups narrowed over time resulting in no significant differences in the aforementioned 3 measures by 2021.

Conclusions

Although racial disparities in outcomes are still apparent, over time, the differences in resource utilization between AA and white patients have narrowed. Initiatives aimed at creating healthier communities with increased access to care and the ultimate goal of equitable care must continue to be pursued.

Postoperative outcomes of mepivacaine vs. bupivacaine in patients undergoing total joint arthroplasty with spinal anesthesia

Background

Spinal anesthesia (SA) has been previously associated with improved outcomes after total joint arthroplasty (TJA). The purpose of this study was to compare outcomes between various local anesthetics.

Methods

This was a retrospective study of 1,328 patients undergoing primary TJA with SA from September 2020–2021 at a single institution. Patients were grouped based on TKA or THA and further separated and analyzed in terms of anesthetic agents—mepivacaine (M), hyperbaric bupivacaine (HB), or isobaric bupivacaine (IB). Subgroup analysis of same-day-discharge (SDD) patients and low- (<11 mg) and high-dose bupivacaine was performed. Statistical significance was assessed at P<0.05.

Results

Mepivacaine use was associated with younger age, lower ASAs, and lower Charlson Comorbidity Index (CCI) scores in both THAs and TKAs. Postoperatively, significant differences were found between HB, IB, and M in LOS, the first PT ambulation distance and rates of SDD, and home discharge in both THAs and TKAs. No significant differences in outcomes were observed between high- and low-dose bupivacaine in THAs or TKAs. In SDD patients, a significant difference was found only in the first 6-clicks mobility scores. After controlling for age, BMI, sex, ASA, and procedure type, mepivacaine was found to be associated with shorter LOS, increased likelihood of SDD, home discharge, POD-0 ambulation, and, further, the first ambulation distance. No significant differences were observed in 6-clicks mobility scores, urinary retention, 30-day ED returns or 30-day readmissions.

Conclusions

Both bupivacaine and mepivacaine are safe and effective local anesthetics for patients undergoing TJA as evidenced by low, similar rates of urinary retention and 30-day ED returns and readmissions. Mepivacaine does appeared to facilitate early ambulation, shorter LOS and home discharge and should be considered as the local anesthetic of choice for patients undergoing rapid recovery TJA.

The role of the lower extremity functional scale in predicting surgical outcomes for total joint arthroplasty patients

Background

The purpose of this study was to evaluate the relationship between lower extremity functional scale (LEFS) scores with postoperative functional outcomes for total joint arthroplasty (TJA) patients and to investigate the utility of this tool to create an individualized plan of care perioperatively.

Methods

Patients undergoing primary TJA at a single institution from 2016 to 2019 was retrospectively reviewed by a univariate analysis in terms of patient characteristics and outcomes across LEFS quartiles. Multivariate regression models were constructed to evaluate the association between the LEFS quartile and outcomes after controlling for confounding factors.

Results

A total of 1389 patients were included. All patients had a documented LEFS pre- and postoperatively with the last value documented at least 60 days to a maximum of 1 year after surgery. The following cutoffs for LEFS quartiles were observed: quartile 1 preoperative LEFS ≤27, quartile 2 ranges from 28 to 35, quartile 3 ranges from 36 to 43, and quartile 4 ≥ 44. Patients with a higher comorbidity burden and ASA score were more likely to have a lower LEFS. Higher levels of preoperative function were significantly associated with shorter LOS and higher rates of same day discharge, independent ambulation, mobility and activity scores, and rates of discharge home.

Conclusion

These findings suggest that LEFS is a useful tool for aiding clinical resource allocation decisions, and incorporation of the measure into existing predictive models may improve their accuracy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42836-021-00106-3.

Postoperative outcomes of total knee arthroplasty across varying levels of multimodal pain management protocol adherence

We examined the effect of varying multimodal pain management (MMPM) combinations on oral morphine milligram equivalents (OMME) and length of stay (LOS) after total knee arthroplasty (TKA). Five groups were compared based on the combination of multimodal analgesics ranging from no MMPM to full MMPM with acetaminophen, gabapentinoids, and celecoxib. After risk adjustment, MMPM was associated with decreased odds of LOS ≥2 days and OMME ≥75th percentile. MMPM protocols are effective at reducing LOS and postoperative narcotic requirements post-TKA. Patients appear to derive similar benefit from receiving all three medications, as well as various combinations of these drugs.

Preoperative Education for Total Joint Arthroplasty: Does Reimbursement Reduction Threaten Improved Outcomes?

BACKGROUND

Nurse navigation programs have been previously shown to reduce cost and improve outcomes after total joint arthroplasty (TJA). Medicare has proposed a 13.7% reduction in professional fee reimbursement for TJA procedures that may adversely impact providers' and health systems' ability to fund ancillary support resources such as nurse navigators.

METHODS

A consecutive series of primary TJAs performed between April 2019 and February 2020 was retrospectively reviewed. Clinical and financial outcomes of patients attending a nurse navigator-led preoperative education class were compared with those who did not attend.

RESULTS

There were 2057 TJAs identified during the study period. Most patients attended the preoperative education class (82.7%) and were discharged home (92.8%). Controlling for significant differences between groups, class attendance was associated with reduced length of stay (LOS), increased chance of 0- or 1-day LOS, reduced chance of discharge to a skilled nursing facility, and reduced hospital charges. For this patient sample, a proposed 13.7% reduction in nurse navigator-led classes was modeled to increase overall cost to payers by >$400,000 annually. Complete elimination of this class was estimated to increase the total annual cost by >$5,700,000 and cost per TJA by >$2700.

CONCLUSION

The use of a nurse navigator-led preoperative education class was associated with shorter LOS, more frequent 0- and 1-day LOS, reduced discharge to skilled nursing facilities, and lower total hospital charges for those patients who attended. Potential reductions proposed by Medicare may interfere with the ability to support such services and negatively impact both clinical and financial outcomes.

General vs Neuraxial Anesthesia in Direct Anterior Approach Total Hip Arthroplasty: Effect on Length of Stay and Early Pain Control

BACKGROUND

Recent literature has suggested some benefits for neuraxial anesthesia (NA) as an alternative for general anesthesia (GA) for primary total hip arthroplasty patients. We examined the impact of NA vs GA on outcomes for patients undergoing direct anterior (DA) approach total hip arthroplasty (THA) in an institution with established rapid recovery protocols.

METHODS

A retrospective review was conducted for 500 consecutive THA patients from a single institution. Univariate analysis and multivariate linear regression were used to compare outcomes for THA patients receiving NA and GA.

RESULTS

There was a significant difference in length of stay with NA patients having a shorter length of stay (NA 32.7 hours vs GA 38.1 hours, P = .003). Patients receiving NA had significantly lower PACU morphine milligram equivalents (MME) (NA 10.2 MME vs GA 15.6 MME, P < .001) and reported a lower score on the PACU pain numeric rating scale (NA 2.1 vs GA 3.7, P < .001).

CONCLUSION

Neuraxial anesthesia is associated with decreased LOS, decreased PACU MME, and a lower PACU pain score for patients undergoing primary DA THA. These trends remained consistent when controlling for age, gender, BMI, and ASA.

Impact of Dexamethasone on Length of Stay and Early Pain Control in Direct Anterior Approach Total Hip Arthroplasty With Neuraxial Anesthesia

BACKGROUND

Dexamethasone has been shown to reduce postoperative pain and opioid consumption for total joint arthroplasty patients; however, its impact on patients who received neuraxial anesthesia (NA) is not well described. We examined the impact of perioperative dexamethasone on outcomes for patients undergoing direct anterior approach total hip arthroplasty (THA) under NA.

METHODS

A retrospective review was conducted for 376 THA patients from a single institution. Univariate analysis was used to compare postoperative outcomes for 164 THA patients receiving dexamethasone compared to 212 who did not receive dexamethasone.

RESULTS

No differences in age, gender, body mass index, or American Society of Anesthesiologists (ASA) Score were observed between the groups. Patients receiving perioperative dexamethasone reported statistically significantly lower postanesthesia care unit (PACU) pain numeric rating scale (Dexamethasone 1.6 vs No dexamethasone 2.3, P = .014) and received lower PACU morphine milligram equivalents (MME) (Dexamethasone 8.57 vs No dexamethasone 11.44, P < .001). Patients receiving dexamethasone had significantly shorter LOS (Dexamethasone 29.40 vs No dexamethasone 35.26 hrs., P < .001).

CONCLUSION

Perioperative dexamethasone is associated with decreased postoperative pain and narcotic consumption, and shorter length of stay for patients undergoing primary direct anterior approach THA with NA.

Risk factors for progression to total knee arthroplasty within two years of presentation for knee osteoarthritis

INTRODUCTION

Knee osteoarthritis (OA) is a leading cause of disability and functional limitations in aging adults. Total knee arthroplasty (TKA) is the gold standard treatment of this condition. The purpose of this study is to evaluate which patient characteristics are associated with proceeding to TKA.

METHODS

Retrospective review of patients with knee osteoarthritis at a single institution was conducted. Demographic, radiographic and clinical patient characteristics were analyzed. The primary outcome measure was whether patients underwent TKA over the study time-period. Univariate comparisons between patients not undergoing surgery and those undergoing TKA were performed. Multivariate logistic regression was performed to evaluate risk factors for undergoing TKA.

RESULTS

Two hundred seven patients were included in the study. One hundred eighty seven patients (90.3%) did not undergo surgery, while 20 (9.7%) underwent TKA. No statistically significant differences in demographics were observed between patients who underwent TKA and those who did not. On multivariate analysis, patients with Kellgren Lawrence grade 4 OA (OR: 20.793, p = 0.009) and varus alignment (OR: 13.044, p = 0.040) were at significantly increased risk of undergoing TKA. Using only these two variables, the area under the curve for predicting which patients would undergo TKA was 0.846, indicating excellent discrimination.

CONCLUSION

In patients diagnosed with knee OA, Kellgren Lawrence grade 4 classification and varus knee alignment are significant risk factors for undergoing TKA, and are associated with a decreased time from initial presentation to surgery. These findings may be used to counsel patients, aid triage decisions, and inform the development of future predictive models.

Preoperative Predictors of Same-Day Discharge After Total Knee Arthroplasty

Background

In January 2020, The Centers for Medicare and Medicaid Services approved total knee arthroplasty (TKA) to be performed in ambulatory surgery centers (ASCs). This study aims to develop a predictive model for targeting appropriate patients for ASC-based TKA.

Methods

A retrospective review of 2266 patients (205 same-day discharge [SDD; 9.0%] and 2061 one-day length of stay [91.0%]) undergoing TKA at a regional medical center between July 2016 and September 2020 was conducted. Multiple logistic regression was used to evaluate predictors of SDD, as these patients represent those most likely to safely undergo TKA in an ASC.

Results

Controlling for other demographics and comorbidities, patients with the following characteristics were at reduced odds of SDD: increased age (odds ratio [OR] = 0.935, P < .001), body mass index ≥35 (OR = 0.491, P = .002), female (OR = 0.535, P < .001), nonwhite race (OR = 0.456, P = .003), primary hypertension (OR = 0.710, P = .032), ≥3 comorbidities (OR = 0.507, P = .002), American Society of Anesthesiologists score ≥3 (OR = 0.378, P < .001). The model was deemed to be of adequate fit using the Hosmer and Lemeshow test (χ² = 12.437, P = .112), and the area under the curve was found to be 0.773 indicating acceptable discrimination.

Conclusion

For patients undergoing primary TKA, increased age, body mass index ≥35, female gender, nonwhite race, primary hypertension, ≥3 comorbidities, and American Society of Anesthesiologists score ≥3 decrease the likelihood of SDD. A predictive model based on readily available patient presentation and comorbidity characteristics may aid surgeons in identifying patients that are candidates for SDD or ASC-based TKA.

Risk factors for severe illness in hospitalized Covid-19 patients at a regional hospital

BACKGROUND

The Covid-19 pandemic threatens to overwhelm scarce clinical resources. Risk factors for severe illness must be identified to make efficient resource allocations.

OBJECTIVE

To evaluate risk factors for severe illness.

DESIGN

Retrospective, observational case series.

SETTING

Single-institution.

PARTICIPANTS

First 117 consecutive patients hospitalized for Covid-19 from March 1 to April 12, 2020.

EXPOSURE

None.

MAIN OUTCOMES AND MEASURES

Intensive care unit admission or death.

RESULTS

In-hospital mortality was 24.8% and average total length of stay was 11.82 days (95% CI: 10.01 to 13.63 days). 30.8% of patients required intensive care unit admission and 29.1% required mechanical ventilation. Multivariate regression identified the amount of supplemental oxygen required at admission (OR: 1.208, 95% CI: 1.011-1.443, p = .037), sputum production (OR: 6.734, 95% CI: 1.630-27.812, p = .008), insulin dependent diabetes mellitus (OR: 11.873, 95% CI: 2.218-63.555, p = .004) and chronic kidney disease (OR: 4.793, 95% CI: 1.528-15.037, p = .007) as significant risk factors for intensive care unit admission or death. Of the 48 patients who were admitted to the intensive care unit or died, this occurred within 3 days of arrival in 42%, within 6 days in 71%, and within 9 days in 88% of patients.

CONCLUSIONS

At our regional medical center, patients with Covid-19 had an average length of stay just under 12 days, required ICU care in 31% of cases, and had a 25% mortality rate. Patients with increased sputum production and higher supplemental oxygen requirements at admission, and insulin dependent diabetes or chronic kidney disease may be at increased risk for severe illness. A model for predicting intensive care unit admission or death with excellent discrimination was created that may aid in treatment decisions and resource allocation. Early identification of patients at increased risk for severe illness may lead to improved outcomes in patients hospitalized with Covid-19.

Outpatient, Home-Based Physical Therapy Promotes Decreased Length of Stay and Post-Acute Resource Utilization After Total Joint Arthroplasty

BACKGROUND

Patients and healthcare systems are increasingly focused on evaluating interventions that increase the value of care delivered. Our objective of this study is to evaluate early post-operative outcomes among those patients who underwent total joint arthroplasty with and without the participation in our piloted Outpatient Physical Therapy Home Visits (OPTHV) program.

METHODS

A retrospective analysis of patients undergoing total hip arthroplasty and total knee arthroplasty at a single institution from July 2016 to September 2017 was performed. Matched cohorts were compared according to OPTHV enrollment status.

RESULTS

In total, 1729 patients were included in this study. Two hundred ninety-three patients were enrolled in OPTHV, while 1436 patients received institutional standard care. Patients were matched by gender (56.7% vs 57.7% female, P = .751), age (67.75 vs 66.95 years, P = .167), body mass index (30.18 vs 30.12 kg/m², P = .859), and average American Society of Anesthesiologists score (2.31 vs 2.36, P = .131). OPTHV patients had a shorter length of stay (1.39 vs 1.64 days, P < .001) and were more likely to discharge to home (89.8% vs 74.7%, P < .001). Ninety-day re-admissions (2.7% vs 2.6%, P = .880) and emergency room visits (4.1% vs 4.3%, P = .864) were equivalent.

CONCLUSION

OPTHV is a novel program that facilitates discharge home and decreased length of stay after total joint arthroplasty without increasing re-admissions or emergency room visits. Utilization of OPTHV may contribute toward reducing the episode of care costs by reducing utilization of skilled nursing facility and home health services. Further prospective studies are needed to evaluate the effect of OPTHV on the total cost of care and functional outcomes.

The Effect of Psychiatric Diagnosis and Psychotropic Medication on Outcomes Following Total Hip and Total Knee Arthroplasty

BACKGROUND

Nearly 20% of the US adult population lives with mental illness, and less than 50% of these receive treatment. Preoperative mental health may affect postoperative outcomes in patients undergoing total joint arthroplasty (TJA), yet is rarely addressed; poor outcomes increase the cost of care and burden on the healthcare system. This study examines the influence of patients with psychiatric diagnosis (PD) and taking psychotropic medication (PM) on emergency room visits, readmissions, and discharge disposition following TJA.

METHODS

Single institution retrospective analysis of a consecutive series of 3020 primary TJA performed between January 2017 and June 2018. Chi-squared, t-tests, and analysis of variance were used to quantify differences between groups.

RESULTS

Nine hundred seventy-six (32.3%) patients had a PD, most had depression (10.1%), anxiety (8.6%), or both (8.4%); 808 (26.8%) patients were on PM. Patients with PD were more likely to experience emergency room visits (6.3% vs 10.0%, P = .034) and skilled nursing facility discharge (11.6% vs 17.9%, P = .005). Patients taking PM were more likely to experience skilled nursing facility discharge (12.4 vs 17.1, P = .047); those taking >2 PM had the highest rate (21.6%).

CONCLUSION

Patients with PD on or off PM may experience increased healthcare utilization in the postoperative period. Increased patient education and support may reduce these discrepancies. PD is not a deterrent for TJA, but targeted interventions should be developed to provide additional support where needed and avoid unnecessary utilization of resources.

Differences in Perioperative Outcomes and Complications Between African American and White Patients After Total Joint Arthroplasty

BACKGROUND

Racial disparities in healthcare utilization and outcomes have been reported and have wide-reaching implications for individual patient and healthcare system; as providers we bear an ethical burden to address this disparity and provide culturally competent care. This study will examine the influence of race on length of stay, discharge disposition, and complications requiring reoperation following total joint arthroplasty (TJA).

METHODS

Single institution retrospective analysis of a consecutive series of 7208 primary TJA procedures performed between July 2013 and June 2017 was conducted. Chi-squared and t-tests were used to quantify differences between the groups and multiple logistic regression was used to identify race as an independent risk factor.

RESULTS

In total, 6182 (84.3%) white and 1026 (14.0%) African American (AA) patients were included. AA patients were younger (63.62 vs 66.84 years, P < .001), more likely female (68.8% vs 57.0%, P < .001), had a longer length of stay (2.19 vs 2.00 days, P < .001), more likely to experience septic complications (1.3% vs 0.5%, P = .002) and manipulation under anesthesia (3.9% vs 1.8%, P < .001), and less likely to discharge home (67.1% vs 81.1%, P < .001). Multiple logistic regression showed that AA patients were more likely to discharge to a facility (adjusted odds ratio 2.63, 95% confidence interval 2.19-3.16, P < .001) and experience a manipulation under anesthesia (adjusted odds ratio 1.90, 95% confidence interval 1.26-2.85, P = .002).

CONCLUSION

AA patients undergoing TJA were younger with longer length of stay and a higher rate of nonhome discharge; AA race was identified as an independent risk factor. Further study is required to understand the differences identified in this study. Targeted interventions should be developed to attempt to eliminate the disparity.

Insulin-Dependent Diabetes Is an Independent Risk Factor for Complications and Readmissions After Total Joint Replacements

This study examined the risk for postoperative complications, reoperations, and readmissions for patients with insulin-dependent diabetes mellitus (IDDM), patients with non-insulin-dependent diabetes mellitus (NIDDM), and patients without diabetes undergoing total joint replacements (TJRs). The American College of Surgeons National Surgical Quality Improvement Program database was queried for all primary TJRs in 2015. The study identified 78,744 TJRs (84.1% nondiabetic patients, 12.0% NIDDM, and 3.9% IDDM). Multiple logistic regression models identified IDDM as an independent risk factor for increased blood loss, myocardial infarctions, pneumonia, renal insufficiency, urinary tract infections, and readmissions when compared with both NIDDM and nondiabetics. Risk for wound complications and reoperations were comparable between all three groups. IDDM increases the risk for medical complications and readmissions after TJRs. Physicians must counsel patients on the increased risks associated with IDDM before elective surgery and provide appropriate medical support for these patients. (Journal of Surgical Orthopaedic Advances 27(4):294-298, 2018).

Opioid Prescriptions After Total Joint Arthroplasty

Prescription opioids are commonly prescribed for pain relief after total joint arthroplasty (TJA), yet little is known about the quantity of opioids prescribed after surgery. This study retrospectively reviewed a consecutive series of 1000 TJAs from April 2014 through September 2015. Postoperative opioid prescriptions were quantified using standardized morphine milligram equivalents (MME). Eighty-four percent of total knee arthroplasty (TKA) and 77% of total hip arthroplasty (THA) patients were opioid naïve. The median opioid volume of the first prescription for those undergoing TKA was greater than for those undergoing THA (600 vs. 450 MME), as was the proportion of individuals requiring one or more refills (48% vs. 32%). The total volume of opioids after TKA was also higher than for total hip replacement (870 vs. 525 MME). Patients who were not opioid naïve were prescribed substantially more opioids than their counterparts after TKA (mean 1593 vs. 1064 MME, p < .001) and THA (mean 1031 vs. 663 MME, p < .001). Decreasing opioid use before surgery may decrease total volume of opioid prescriptions after TJA. (Journal of Surgical Orthopaedic Advances 27(3):231-236, 2018).

The Cost of Unnecessary Hospital Days for Medicare Joint Arthroplasty Patients Discharging to Skilled Nursing Facilities

BACKGROUND

The 72-hour Medicare mandate (3-night stay rule) requires a 3-day inpatient stay for patients discharging to skilled nursing facilities (SNFs). Studies show that 48%-64% of Medicare total joint arthroplasty (TJA) patients are safe for discharge to SNFs on postoperative day (POD) #2. The purpose of this study was to extrapolate the financial impact of the 3-night stay rule.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program database was queried for all primary TJAs performed in 2015. Discharge destination was recorded. Institutional cost accounting examined costs for patients discharging on POD #2 vs POD #3.

RESULTS

A total of 42,423 TJAs (14,395 total hip arthroplasties [THAs] and 28,028 total knee arthroplasties [TKAs]) were performed in patients over the age of 65 years. Of these patients, 5252 THAs (36.5%) and 12,022 TKAs (42.9%) were discharged from the hospital on POD #3, with 2404 THAs (16.7%) and 5083 TKAs (18.1%) being discharged to SNFs. Institutional cost accounting revealed hospital costs for THA were $2014 more, whereas hospital costs for TKA were $1814 more for a 3-day length of stay when compared with a 2-day length of stay (P < .001). The mean charge per day for an SNF was $486.

CONCLUSION

The National Surgical Quality Improvement Program database is a representative sample of all surgeries performed in the United States. Extrapolating our findings to all Medicare TJAs nationally gives an estimated $63 million in annual savings. Medicare mandated, but potentially medically unnecessary inpatient days at a higher level of care increase the total cost for TJAs. Policies regarding minimum stay requirements before discharge should be re-evaluated.

The Impact of Surgical Technique on Patient Reported Outcome Measures and Early Complications After Total Hip Arthroplasty

BACKGROUND

This study examines patient and surgeon reported outcome measures, complications during index admission, length of stay (LOS), and discharge disposition in a series of total hip replacements (THR) performed via the direct anterior (DA) or posterolateral (PL) approach.

METHODS

Five surgeons performed 2698 total hip replacements (1457 DA vs 1241 PL) between January 2010 and June 2015. Complications during index admission were recorded using billing and claims data. Harris Hip Scores (HHS) and Hip disability and Osteoarthritis Outcome Scores (HOOS) were collected in a subset of patients.

RESULTS

Patients in the DA group had shorter LOS (2.3 DA vs 2.7 PL days, P < .001) and a larger proportion of patient discharges to home (79.0% DA vs 68.7% PL, P < .001). Surgical (0.75% DA vs 0.73% PL, P = .961) and medical (8.4% DA vs 8.1% PL, P = .766) complications during index admission were equivalent between groups. HHS (n = 462) favored the DA group at an early follow-up (P < .001), but did not differ at 1 year (P = .478). Logistic regression revealed that patients in the DA group were more likely to report no pain, no limp, walk unlimited distances, and climb stairs without the use of the railing at 3- to 6-month follow-up (P < .001). HOOSs were equivalent at all follow-ups regardless of approach.

CONCLUSION

Patients in the DA group had shorter LOS and were more likely to be discharged home. The DA group had better HHS at 3- to 6-month follow-up than patients in the PL group, with no difference in medical or surgical complications during index admission.

Incidence, Risk Factors, and Costs for Hospital Returns After Total Joint Arthroplasties

BACKGROUND

Unplanned hospital returns after total joint arthroplasty (TJA) reduce any cost savings in a bundled reimbursement model. We examine the incidence, risk factors, and costs for unplanned emergency department (ED) visits and readmissions within 30 days of index TJA.

METHODS

We retrospectively reviewed a consecutive series of 655 TJAs (382 total knee arthroplasty and 273 total hip arthroplasty) performed between April 2014 and March 2015. Preoperative diagnosis was osteoarthritis of the hip or knee (97%) or avascular necrosis of the hip (3%). Hospital costs were recorded for each ED visit and readmission episode.

RESULTS

Of the 655 TJAs reviewed, 55 (8.4%) returned to the hospital. Of these hospital returns, 35 patients (5.3%) returned for a total of 36 unplanned ED visits whereas the remaining 20 patients (3.1%) presented 22 readmissions within 30 days of index TJA. The 2 most common reasons for unplanned ED visits were postoperative pain/swelling (36%) and medication-related side effects (22%). Avascular necrosis of the hip was a significant risk factor for an unplanned ED visit (7.27 odds ratio [OR], 95% confidence interval [CI] 1.67-31.61, P = .008). Multiple logistic regression analysis revealed the following risk factors for readmission: body mass index (1.10 OR, 95% CI 1.02-1.78, P = .013), comorbidity >2 (2.07 OR, 95% CI 1.06-6.95, P = .037), and prior total knee arthroplasty (2.61 OR, 95% CI 1.01-6.72, P = .047). Ambulating on the day of surgery trended toward a lower risk for readmission (0.13 OR, 95% CI 0.02-1.10, P = .061). The 2 most common reasons for readmission were ileus (23%) and cellulitis (18%). The total cost associated with unplanned ED visits were $15,427 whereas costs of readmissions totaled $142,654.

CONCLUSION

Unplanned ED visits and readmissions in the forthcoming bundled payments reimbursement model will reduce cost savings from rapid recovery protocols for TJA. Identifying and mitigating preventable causes of unplanned visits and readmissions will be critical to improving care and controlling costs.

Who Is Not a Candidate for a 1-Day Hospital-Based Total Knee Arthroplasty?

BACKGROUND

Short-stay total knee arthroplasty (TKA), defined as a 1-day length of stay (LOS), is feasible in many patients, yet variables identifying who are candidates for a short stay are not well described in literature. With an emphasis on cost-efficiency, we examined preoperative patient characteristics and perioperative hospital factors that correlated with a longer LOS.

METHODS

A retrospective review of 381 primary TKAs was performed. Clinical measures differentiating a 1-day LOS group from that of a ≥2-day LOS group were identified.

RESULTS

Multiple logistic regression demonstrated older age (odds ratio [OR], 1.92; 95% confidence interval [CI], 1.34-2.77; P < .001), female gender (OR, 4.22; 95% CI, 2.35-7.57; P < .001), American Society of Anesthesiologists score 3 or 4 (OR, 2.00; 95% CI, 1.01-3.95; P = .046), atrial fibrillation (OR, 8.87; 95% CI, 1.81-43.47; P = .007), and prior TKA on the contralateral side (OR, 3.57; 95% CI, 1.27-10.05; P = .016) as significant preoperative characteristics correlating with the ≥2-day LOS group. The most significant hospital perioperative factor associated with longer stays was patients not ambulating on the day of surgery (OR, 4.09; 95% CI, 1.77-9.48; P = .001). Walking 150 ft (93% sensitive, 35% specific) on the day of surgery was predictive of patients in the 1-day LOS group. Hospital costs were US$1873 (P < .001) lower for patients in the 1-day group.

CONCLUSION

Shorter stays decrease costs associated with TKA, and more refined predictive models are needed to optimize discharge protocols. Preoperative data help allocate limited healthcare resources toward patients more likely to leave in 1 day, while perioperative data facilitate learning to create a more efficient hospital process.

Do shorter lengths of stay increase readmissions after total joint replacements?

Background

Enhanced recovery after surgery protocols for total joint replacements (TJRs) emphasize early discharge, yet the impact on readmissions is not well documented. We evaluate the impact of a one-day length of stay (LOS) discharge protocol on readmissions.

Methods

We conducted a retrospective review of all primary TJRs (hip and knee) from April 2014 to March 2015. Patients who had adequate support to be discharged home were categorized into 2 groups, 1-day (n = 174) vs 2-day (n = 285) LOS groups. Patients discharged to rehabilitation were excluded (n = 196).

Results

Patients in the 1 day group were more likely to be younger (61.7 vs 64.8 years, P < .001), be male (56.3% vs 40.4%, P = .001), and have a lower body mass index (30.0 vs 31.4 kg/m², P = .012). One-day LOS patients had shorter surgical times (79.7 vs 85.6 minutes, P = .001) and more likely had spinal anesthesia (46.0% vs 31.2%, P = .001). The overall 30-day all-cause (2.3% vs 2.5%, P = .591) and 90-day wound-related (1.1% vs 1.1%, P = .617) readmission rates were equivalent between groups.

Conclusions

Early discharge does not increase readmissions and may help attenuate costs associated with TJRs. Further refinement of protocols may allow for more patients to be safely discharged on postoperative day 1.

Potential Operating Room Fire Hazard of Bone Cement

Approximately 600 cases of operating room (OR) fires are reported annually. Despite extensive fire safety education and training, complete elimination of OR fires still has not been achieved. Each fire requires an ignition source, a fuel source, and an oxidizer. In this case report, we describe the potential fire hazard of bone cement in the OR. A total knee arthroplasty was performed with a standard medial parapatellar arthrotomy. Tourniquet control was used. After bone cement was applied to the prepared tibial surface, the surgeon used an electrocautery device to resect residual lateral meniscus tissue-and started a fire in the operative field. The surgeon suffocated the fire with a dry towel and prevented injury to the patient. We performed a PubMed search with a cross-reference search for relevant papers and found no case reports outlining bone cement as a potential fire hazard in the OR. To our knowledge, this is the first case report identifying bone cement as a fire hazard. OR fires related to bone cement can be eliminated by correctly assessing the setting time of the cement and avoiding application sites during electrocautery.

Constrained condylar knee without stem extensions for difficult primary total knee arthroplasty

Two hundred forty-eight constrained condylar total knee arthroplasties consecutively implanted without the use of diaphyseal stem extensions were studied in 180 patients. Preoperative deformity was severe (82% Ahlbäck grade 4-5). One hundred ninety-two knees (148 patients) were reviewed at mean 47-month follow-up (range: 24-72 months). Knee Society score improved from 36 to 89 points, and function score improved from 42 to 76 points. Failure rate was 2.5% (2 infections, 1 aseptic loosening, 1 supracondylar femoral fracture, and 1 tibial post fracture). Five (2.5%) knees had patellofemoral complications. Nonprogressive radiolucent lines were present in 16% of cases. Use of a nonmodular constrained condylar knee for primary severely damaged knees demonstrated reliable short- to mid-term results with a low complication rate and questioned the routine use of intramedullary stem extensions in all such cases.

Knee arthrodesis

Arthrodesis is one of the last options available to obtain a stable, painless knee in a patient with a damaged knee joint that is not amenable to reconstructive measures. Common indications for knee arthrodesis include failed total knee arthroplasty, periarticular tumor, posttraumatic arthritis, and chronic sepsis. The primary contraindications to knee fusion are bilateral involvement or an ipsilateral hip arthrodesis. A variety of techniques has been described, including external fixation, internal fixation by compression plates, intramedullary fixation through the knee with a modular nail, and antegrade nailing through the piriformis fossa. Allograft or autograft may be necessary to restore lost bone stock or to augment fusion. For the carefully selected patient with realistic expectations, knee arthrodesis may relieve pain and obviate the need for additional surgery or extensive postoperative rehabilitation.

Primary constrained condylar knee arthroplasty without stem extensions for the valgus knee

Avoiding stem extensions in total knee arthroplasties may decrease operative time, prosthetic cost, and canal invasion at surgery. A constrained condylar knee implant without stem extensions also likely will be easier to revise and will eliminate the risk of end of stem pain. Our hypothesis was that a constrained condylar knee implant for primary severely deformed knees would show excellent midterm results with a low rate of aseptic loosening, even without diaphyseal-engaging stems. We retrospectively reviewed 70 consecutive primary constrained condylar knee implants without stem extensions from 1998 to 2001 in 61 patients with knees in 15 degrees valgus or greater. Forty-nine patients (55 knees) were followed up for 44.5 months (range, 2-6 years). Outcome was assessed using the Knee Society scoring system. Knee Society score and functional scores improved from 34 points and 40 points to 93 and 74 points, respectively. No radiographic loosening or wear was found. There were no peroneal nerve palsies, and no patients had flexion or medial instability. One patient was affected by chronic patellar dislocation. Constrained condylar knee implants in patients with severe valgus deformity resulted in pain relief and improved function, without substantial complications at midterm followup, without diaphyseal-engaging stem extensions.

LEVEL OF EVIDENCE

Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

A CCD-based system for the detection of DNA in electrophoresis gels by UV absorption

A method and apparatus for the detection and quantification of large fragments of unlabelled nucleic acids in agarose gels is presented. The technique is based on ultraviolet (UV) absorption by nucleotides. A deuterium source illuminates individual sample lanes of an electrophoresis gel via an array of optical fibres. As DNA bands pass through the illuminated region of the gel the amount of UV light transmitted is reduced because of absorption by the DNA. During electrophoresis the regions of DNA are detected on-line using a UV-sensitive charge coupled device (CCD). As the absorption coefficient is proportional to the mass of DNA the technique is inherently quantitative. The mass of DNA in a region of the gel is approximately proportional to the integrated signal in the corresponding section of the CCD image. This system currently has a detection limit of less than 1.25 ng compared with 2-10 ng for the most popular conventional technique, ethidium bromide (EtBr) staining. In addition the DNA sample remains in its native state. The removal of the carcinogenic dye from the detection procedure greatly reduces associated biological hazards.

Assessing the effectiveness of different urinary catheters in emptying the bladder: an application of transvaginal ultrasound

The effectiveness of different types of urinary catheters in completely draining the bladder has not been tested. Transvaginal ultrasound, which is able to measure bladder volumes in women from 2 to 175 ml, provides a means of measuring any fluid volume remaining in the bladder following catheter drainage. Using transvaginal ultrasound, the post-catheterisation bladder volumes were measured in 26 female patients; 14 underwent urethral catheterisation using either a 14F short plastic female catheter or a Foley catheter of the same size (balloon not inflated); 12 had an indwelling 12F suprapublic catheter following bladder neck surgery. The mean post-catheterisation bladder volumes after using the short plastic female and Foley catheters were less than 1 ml and 77 ml respectively. A short plastic catheter should be used in women to collect the residual urine volume by urethral catheterisation. A Foley catheter is relatively ineffective in this task. A 12F suprapubic catheter was found to drain the bladder relatively well. The mean post-catheterisation bladder volume was 35 ml. Prior to removing a suprapubic catheter post-operatively, it is recommended that the residual urine volume (measured using the suprapubic catheter) be checked by measuring the post-catheterisation bladder volume (using either a short plastic catheter or transvaginal ultrasound).