Characterizing Intraoperative Vasopressor Use in Total Knee Arthroplasty: A Retrospective Cohort Study.

Preoperative optimization and protocols for joint replacement care pathways have led to decreased length of stay (LOS)and narcotic use, and are increasingly important in delivering quality, cost savings, and shifting appropriate cases to an outpatient setting. The intraoperative use of vasopressors is independently associated with increased LOS and risk of adverse postoperative events including death, and in total hip arthroplasty, there is an increased risk for intensive care unit (ICU) admission. Our aim is to characterize the patient characteristics associated with vasopressor use specifically in total knee arthroplasty (TKA). We retrospectively reviewed the electronic medical records of a cohort of patients who underwent inpatient primary TKA at a single academic hospital from January 1, 2017 to December 31, 2018. Demographics, comorbidities, perioperative factors, and intraoperative medication administration were compared with multivariate regression to identify patients who may require intraoperative vasopressors. Out of these, 748 patients underwent TKA, 439 patients required intraoperative vasopressors, while 307 did not. Significant independent predictors of vasopressor use were older age (odds ratio [OR] = 1.06, 95% confidence interval [CI]: 1.03-1.08) and history of a prior cerebrovascular accident (CVA; OR = 11.80, CI: 1.48-93.81). While not significant, male sex (OR = 0.72, CI: 0.50-1.04) and regional anesthesia (OR = 0.64, CI: 0.40-1.05) were nearing significance as negative independent predictors of vasopressor use. In a secondary analysis, we did not observe an increase in complications attributable to vasopressor administration intraoperatively. In conclusion, nearly 59% of patients undergoing TKA received intraoperative vasopressor support. History of stroke and older age were significantly associated with increased intraoperative vasopressor use. As the first study to examine vasopressor usage in a TKA patient population, we believe that understanding the association between patient characteristics and intraoperative vasopressor support will help orthopaedic surgeons select the appropriate surgical setting during preoperative optimization.

Reduced Narcotic Utilization in Total Joint Arthroplasty Patients in an Urban Tertiary Care Center.

Background: Opioid use after total joint arthroplasty must be balanced against the risks of opioid dependence and diversion. This study sought to define the baseline patient characteristics and discharge opioid use after the initiation of a preoperative and postoperative institutional opioid prescription protocol in a population with a high prevalence of opioid dependence and substance use. Methods: Data on 1004 patients undergoing total joint arthroplasties from July 1, 2017, to June 30, 2019, were retrospectively reviewed. Demographics were collected, and data were grouped into high- and low-discharge opioid groups based on 1 standard deviation above or below the mean. Patient characteristics of the high and low groups were compared using one-way analysis of variance and Pearson chi-square test. Results: The prevalence of preoperative opioid dependence was 21.8%. The mean discharge opioid prescription was 264 morphine milligram equivalents (MMEs). The cutoffs of high- and low-use groups were above 424 MMEs and below 104.5 MMEs. The high-discharge opioid group was more likely to be male, younger, to have a history of preoperative opioid use, to undergo general anesthesia, and to be uninsured. The lower-discharge opioid group was more likely to be older, female, to have Medicare, and to stay approximately 1 day longer in the hospital. Body mass index, intraoperative opioid requirement, American Society of Anesthesiologists Classification score, race, total knee vs total hip arthroplasty, or surgical approach for total hip arthroplasty did not affect discharge opioid prescriptions. Conclusions: Reduction of opioid prescriptions at discharge in total joint arthroplasty patients may be possible with the use of preoperative and postoperative protocols, optimizing patient risk factors for opioid use and utilizing a patient-specific opioid taper regimen.

Catastrophic Failure of the Tibial Component After Total Knee Arthroplasty: Fracture and Dissociation Between the Baseplate and Stem.

Fracture of the tibial component can be a devastating complication after primary total knee arthroplasty. While fractures of the tibial baseplate have been reported, failure at the junction between the baseplate and stem has not been well-described. We present a 49-year-old male who developed progressively worsening left knee pain and an effusion 7-8 years after an index total knee arthroplasty. Radiographs revealed component subsidence and subtle asymmetry between the baseplate and stem. At the time of revision, the tibial component was found to be fractured at the junction of the baseplate and stem, with complete dissociation between the two pieces. Clinicians should maintain a high index of suspicion for catastrophic failure, as this rare phenomenon can be subtle on radiographs and requires close monitoring for signs of component subsidence.

Important Factors for Retrograde Nailing Through Total Knee Arthroplasty: A Cadaveric Study.

OBJECTIVES: Evaluate how total knee arthroplasty (TKA) implant design, femoral component size, and preoperative knee range of motion affect retrograde femoral nailing. METHODS: Cadaveric specimens were prepared for TKA with a single radius (SR) or medial pivot (MP) design and tested with cruciate retaining (CR), cruciate substituting (CS), and posterior stabilizing (PS) 9-mm liners. Knee extension identified the minimum flexion required to pass an opening reamer without impinging on TKA components. The angle between the reamer path and the femoral shaft was calculated from lateral fluoroscopic images. RESULTS: In SR TKA, the average flexion required was 70, 71, and 82 degrees for CR, CS, and PS, respectively. The required flexion in PS was significantly greater (P = 0.03). In MP TKA, the average flexion required was 74, 84, and 123 degrees for CR, CS, and PS, respectively. The required flexion was significantly greater in CS and PS designs (P < 0.0001). Femoral component size did not affect the minimum flexion required. The entry reamer resulted in 9.2 (SR) and 12.5 (MP) degrees of apex anterior deviation. CONCLUSIONS: When performing retrograde nailing through either of these TKA designs with a 12-mm opening reamer, at least 70 degrees of knee flexion is required to avoid damage to the polyethylene liner or femoral component. PS implants require significantly more flexion with both TKA designs. Femoral component size did not affect the flexion requirement. Approximately a 10-degree deviation exists between the reamer path and femoral shaft.

Common Practices in Intra-Articular Corticosteroid Injection for the Treatment of Knee Osteoarthritis: A Survey of the American Association of Hip and Knee Surgeons Membership.

BACKGROUND: Knee osteoarthritis nonoperative management options remain limited. Our aim is to define the current American Association of Hip and Knee Surgeons (AAHKS) members' practices and perceptions in terms of the frequency, formulation, use of concomitant aspiration, maximum lifetime number of injections, efficacy, interval between injection and surgery and complication rates. METHODS: A 22-question survey based on Likert scale response anchors was approved and distributed by the AAHKS Research Committee to its membership by email during the Spring 2019 meeting. Data were managed with REDCap software. RESULTS: Membership response totaled 537 of 2365 (22.7%) members. Highlights include every respondent using intra-articular corticosteroid injections (ICIs) in their practice, and most use a three-month minimum interval, although the preferred interval is longer. Near consensus was found waiting three months before surgery. There was a great variability in the number of injections allowed, and injections before surgery were very common. Nearly all responders use a local anesthetic mixture with the cortisone injection, but there was great variation in corticosteroid type: methylprednisolone (42%), triamcinolone (41%), betamethasone (13.3%), and dexamethasone (3.7%). CONCLUSION: The results of our survey indicate the majority of the AAHKS members who completed the survey use ICIs routinely for treatment of knee osteoarthritis. There was near consensus in ICIs, which is effective with decreasing efficacy over serial injections, and an absolute minimum interval between injections was believed by most to be three months with no clearly defined lifetime limit and strong consensus for a three-month preoperative interval. The formulation of steroid, local anesthetic, and skin preparation technique varied greatly.

The Use of Cement in Hip Arthroplasty: A Contemporary Perspective.

Notable advances in hip arthroplasty implants and techniques over the past 60 years have yielded excellent survivorship of fully cemented, hybrid, and reverse hybrid total hip replacements as demonstrated in joint registries worldwide. Major advances in noncemented implants have reduced the use of cement, particularly in North America. Noncemented implants predominate today based on procedural efficiency, concern related to thromboembolic risk, and a historic belief that cement was the primary cause of osteolysis and implant loosening. With the decline of cemented techniques, press-fit fixation has become common even in osteoporotic elderly patients. Unfortunately, there is a troubling rise in intraoperative, as well as early and late postoperative periprosthetic fractures associated with the use of noncemented implants. Despite the success of noncemented fixation, an understanding of modern cement techniques and cemented implant designs is useful to mitigate the risk of periprosthetic fractures. Cemented acetabular components can be considered in elderly patients with osteoporotic or pathologic bone. Cemented stems should be considered with abnormal proximal femoral morphology, conversion of failed hip fixation, inflammatory arthritis, patient age over 75 (especially women), osteoporotic bone (Dorr C), and in the treatment of femoral neck fractures.

Dephosphorylation of threonine-821 of the retinoblastoma tumor suppressor protein (Rb) is required for apoptosis induced by UV and Cdk inhibition.

The Retinoblastoma protein (Rb) is important in the control of cell proliferation and apoptosis. Its activity is controlled by reversible phosphorylation on several serine and threonine residues. When Rb is hypophosphorylated, it inhibits proliferation by preventing passage through the G 1- S phase transition. Hyperphosphorylated Rb promotes cell cycle progression. The role of Rb phosphorylation in the control of apoptosis is largely unknown, although several apoptotic stimuli result in dephosphorylation of Rb. It may be that dephosphorylation of specific amino acids signals apoptosis vs. cell cycle arrest. Using glutamic acid mutagenesis, we have generated 15 single phosphorylation site mutants of Rb to alter serine/threonine to glutamic acid to mimic the phosphorylated state. By calcium phosphate transfection, mutant plasmids were introduced into C33A Rb-null cells, and apoptosis was induced using UV. Apoptosis was measured by ELISA detection of degraded DNA and by immunoblotting to assess proteolytic cleavage of PARP. Our results show that only mutation of threonine-821 to glutamic acid (T821E) blocked apoptosis by 50%, whereas other sites tested had little effect. In Rb-null Saos-2 and SKUT-1 cells, the T821E mutation also blocked apoptosis induced by the cdk inhibitor, Roscovitine, by 50%. In addition, we show that endogenous Rb is dephosphorylated on threonine-821 when cells are undergoing apoptosis. Thus, our data indicates that dephosphorylation of threonine-821 of Rb is required for cells to undergo apoptosis.

Effect of anomalous pulse timing on call discrimination by females of the gray treefrog (Hyla versicolor): behavioral correlates of neurobiology.

Research has demonstrated that certain midbrain neurons of anurans 'count' interpulse intervals (IPIs). Some neurons fire after exposure to fewer intervals than do others. Counting can be reset to zero if an IPI falls outside the cell's tolerance range. We tested female gray treefrogs for behavioral correlates of these neural response patterns using phonotaxis tests in order to gain a better understanding of the mechanistic bases of female responses to calls. For example, previous work demonstrated females often prefer longer to shorter pulsed advertisement calls, even when the former occur at lower rates. Call attractiveness can also be reduced when pulse duration and timing have been manipulated experimentally or disrupted by acoustic interference. In this study, female responses were consistent with neural data, emphasizing the importance of IPIs. Females discriminated in favor of calls with normal interpulse timing relative to those in which a single IPI was too long or too short. Our data suggest that neural resetting of interval counting by inappropriate intervals may more strongly influence females than reduced firing in response to such intervals on an individual basis. Data also suggest a transition point between 125 ms and 175 ms at which an interval between pulse strings is treated as an interval between calls.