Repair of a rat calvaria defect with injectable strontium (Sr)-doped polyphosphate dicalcium phosphate dehydrate (P-DCPD) ceramic bone grafts.

The trace element strontium (Sr) enhances new bone formation. However, delivering Sr, like other materials, in a sustained manner from a ceramic bone graft substitute (BGS) is difficult. We developed a novel ceramic BGS, polyphosphate dicalcium phosphate dehydrate (P-DCPD), which delivers embedded drugs in a sustained pattern. This study assessed the in vitro and in vivo performance of Sr-doped P-DCPD. In vitro P-DCPD and 10%Sr-P-DCPD were nontoxic and eluents from 10%Sr-P-DCPD significantly enhanced osteoblastic MC3T3 cell differentiation. A sustained, zero-order Sr release was observed from 10%Sr-P-DCPD for up to 70 days. When using this BGS in a rat calvaria defect model, both P-DCPD and 10% Sr-P-DCPD were found to be biocompatible and biodegradable. Histologic data from decalcified and undecalcified tissue showed that 10%Sr-P-DCPD had more extensive new bone formation compared with P-DCPD 12-weeks after surgery and the 10%Sr-P-DCPD had more organized new bone and much less fibrous tissue at the defect margins. The new bone was formed on the surface of the degraded ceramic debris within the bone defect area. P-DCPD represented a promising drug-eluting BGS for repair of critical bone defects.

Effect of Commercially Available Wound Irrigation Solutions on Uninfected Host Tissue in a Murine Model.

Background: Commercially available irrigation solutions are used to reduce bacterial contamination and prevent surgical site infections. However, the effect of these solutions on the healing capacity of tissue has not been well-established. The purpose of this study was to investigate the effects of 5 commercially available irrigation solutions on host tissue in a murine model. Methods: There were 5 treatment groups: bacitracin, Clorpactin, Irrisept, Prontosan, Bactisure, and normal saline control. The irrigation solutions were applied to the wound for 30 seconds or 1 minute, as per the manufacturer's instructions, and then washed with normal saline. Mice were sacrificed at 3 days and 10 days. The tissue was examined histologically for inflammation, edema, granulation tissue formation, and re-epithelialization. Granulation tissue formation and re-epithelialization were surrogates for effective wound healing. Results: All of the irrigation solutions had negative effects on host tissue in the acute phase. The inflammation and edema were improved in the later phase (10 days). Recovery and healing of the open wounds were observed for all groups at 10 days. The antiseptic irrigation solutions had similar cytotoxic effects on host tissue at 3 days and did not have delayed or compromised wound healing at 10 days when compared to normal saline control. Conclusions: Single short-duration use of these commercially available antiseptic irrigation solutions appears to be safe in an uninfected wound. Data from this study will provide surgeons with useful information regarding the safety of using antiseptic wound irrigation solutions intraoperatively for prevention of surgical site infections.

Do 'Surgeon Champions' and High-Volume Surgeons Have Lower Rates of Periprosthetic Femur Fracture? Perspective From a State-Wide Quality Improvement Registry.

BACKGROUND: Recently, a state-wide registry identified fracture as a major cause of total hip arthroplasty revision. There were 52.8% of revisions occurring within 6 months (fracture leading cause). Registry sites have a 'surgeon champion' who acts as liaison and advocate. This study evaluated the effect of surgeon volume and role of 'surgeon champion' on fracture rates. METHODS: There were 95,948 cases from 2012 to 2019 queried with peri-implant femoral fractures identified (within 6 months). Funnel plots were generated to compare individual surgeon-specific fracture rates. Surgeons who had a fracture rate below the confidence interval were labeled 'green' (lower than mean), within were 'yellow' (no difference), and above were 'red' (significantly higher). RESULTS: For all surgeons, 19.6% were red, 72.1% yellow, and 8.3% green. There were 17.2% 'surgeon champions' and 6.2% 'nonchampions' that were green (P = .01), while 20.7 and 19.3% were red (P = .82). There was a significant association between volume and performance (P < .01). No surgeons in the lower two quartiles (<84; 84 to 180 cases), while 4 and 29% of higher-volume surgeons (181 to 404; >404 cases) were green. There was no statistical difference in red status by volume (P = .53). CONCLUSION: 'Surgeon champions' and high-volume surgeons were more likely to be high performers but not less likely to be low performers. Active involvement in quality improvement and/or high volume was associated with better outcomes but did not impart complication immunity. 'Green' surgeons should mentor colleagues to help reduce fractures by re-evaluating modifiable factors. Analyzing outcomes to promote quality and decrease complications is paramount.

Early Survivorship of Uncemented Total Knee Arthroplasty Varies by Age and Sex Based on Data From the Michigan Arthroplasty Registry Collaborative Quality Initiative.

BACKGROUND: Outcome data for newer uncemented total knee arthroplasty (TKA) designs has been mixed. Registry studies showed worse survivorship, but clinical trials have not demonstrated differences compared to cemented designs. There has been renewed interest in uncemented TKA with modern designs and improved technology. The utilizations of uncemented knees in Michigan, 2-year outcomes, and the effects of age and sex were evaluated. METHODS: A statewide database from 2017 through 2019 was analyzed for incidence, distribution, and early survivorship of cemented versus uncemented TKAs. There was 2-year minimum follow-up. Kaplan-Meier survival analysis was used to generate time to first revision cumulative percent revision curves. The impacts of age and sex were examined. RESULTS: Use of uncemented TKAs increased from 7.0 to 11.3%. Uncemented TKAs were more commonly men, younger, heavier, American Society of Anesthesiologists score > 2, and opioid users (P < .05). At 2 years, overall cumulative percent revision was higher in uncemented (2.44% [2.00, 2.99]) versus cemented (1.76% [1.64, 1.89]), particularly in women uncemented (2.41 [1.87, 3.12]) versus cemented (1.64 [1.50, 1.80]). Revision rates were greater with uncemented women >70 years (1.2% 1 year, 1.02% 2 years) versus < 70 years (0.56%, 0.53%), notably uncemented were inferior in both groups (P < .05). Men, regardless of age, had similar survivorships with both cemented and uncemented designs. CONCLUSION: The use of an uncemented TKA had an increased risk of early revision compared to cemented. This finding, however, was only apparent in women, especially those >70 years old. Surgeons should consider cement fixation in women >70 years.

A Reduction in Opioid Prescription Size After Total Joint Arthroplasty Can be Safely Performed Without an Increase in Complications.

BACKGROUND: Excessive opioid prescriptions after total joint arthroplasty (TJA) increase risks for adverse opioid-related events, chronic opioid use, and unlawful opioid diversion. Decreasing postoperative prescriptions may improve quality after TJA. Concerns exist that a decrease in opioids prescribed may increase complications, such as readmissions, emergency department (ED) visits, or worsened patient-reported outcomes (PROs). The purpose of this study was to explore whether a reduction in opioids prescribed after TJA resulted in increased complications. METHODS: Data originated from a statewide database prospectively abstracted, including oral morphine equivalents prescribed at discharge, readmissions, ED visits, and PROs. Data were collected from 84,998 TJA occurring 1 year before and after the creation of an opioid-prescribing protocol that had decreased prescriptions by approximately 50%. Trends were monitored using Shewhart control charts. Regression models were used to determine statistically significant changes over time. RESULTS: All groups showed a reduction in opioids prescribed by almost 50% without an increase in emergency room visits or readmissions and without a detrimental effect on PROs. Compared to baseline data before opioid reduction, opioid-naive total knee arthroplasty had significant improvements in all outcomes (P = .03, P = .02, P < .001, P < .001). Opioid-tolerant total knee arthroplasty and total hip arthroplasty had no worsened outcomes and significant improvement in (Knee Injury and Osteoarthritis Outcome score for Joint Replacement P = .03) and (Hip Disability and Osteoarthritis Outcome Score for Joint Replacement P = .03). Opioid-naive total hip arthroplasty had significant improvements in Hip Disability and Osteoarthritis Outcome Score Joint Replacement (P = .003) and Patient Reported Outcomes Measurement Information System (P = .001). CONCLUSIONS: Postoperative opioid prescription recommendations from a statewide registry decreased prescribing by approximately 50% without decreasing PROs or increasing ED visits or readmissions. A reduction in opioids prescribed after TJA can be accomplished safely and without increased complications.

Common Wound Irrigation Solutions Produce Different Responses in Infected vs Sterile Host Tissue: Murine Air Pouch Infection Model.

Background: Despite desirable microbicidal actions of irrigation solutions in surgical site infection treatment, several studies demonstrate potential cytotoxic effects. This study investigated tissue damage caused by irrigation solutions in the presence or absence of infection. Methods: Air pouches were created in 60 mice and evenly divided into 2 groups as infected with Staphylococcus aureus and control. Groups were then subdivided both by type of solution and by timing after irrigation. Solutions included control (0.9% saline), bacitracin (33 IU/ml), 0.2% sodium oxychlorosene, 0.05% chlorhexidine gluconate, and 0.013% benzalkonium chloride. Results: Inflammation decreased in infected pouches compared to the sterile ones for all solutions except bacitracin on day 0 and for all on day 7. On day 0, infected pouches had increased necrosis with bacitracin (P = .006), chlorhexidine gluconate (P = .18), and benzalkonium chloride (P = .07); on day 7, there was decreased necrosis in infected pouches for all solutions (P < .05) except for sodium oxychlorosene (P = .18). Edema decreased in infected pouches on day 0 for all solutions. On day 7, infected pouches had decreased edema with 0.9% saline, bacitracin, and benzalkonium chloride (P < .05) and increased edema with chlorhexidine gluconate (P < .05) and sodium oxychlorosene (P = .069). Bacitracin allowed for more bacteria growth than sodium oxychlorosene (P = .024), chlorhexidine gluconate (P = .025), and benzalkonium chloride (P = .025). Conclusions: The presence of bacteria led to less immediate tissue inflammation and edema, while tissue necrosis varied over time. The current study may guide surgeons on which solution to use and whether to irrigate a possibly sterile wound or joint.

Factors That Influence Time to Operating Room for Geriatric Hip Fractures: A Quality Improvement Initiative.

Background: For geriatric hip fractures, the current American College of Surgeons guideline recommends surgery within 48 hours. We sought to identify which factors delayed a patient's progression to definitive surgery at 2 associated level II trauma centers using chart abstraction. Methods: We reviewed all geriatric patients who underwent a surgical procedure for a hip fracture. Data regarding age, length of stay, procedure, and minutes from emergency department arrival to operating room (OR) were evaluated. Chart abstraction determined if cardiac or medical clearance and an echocardiogram were obtained. For patients that entered the OR over 24 hours, a reason was identified for the delay. Analysis of variance was used to compare continuous data, and chi-squared tests were used for categorical data. Results: Of 477 patients, 288 (60%) presented to the OR in under 24 hours, 114 (24%) between 24 and 36 hours, and 75 (16%) over 36 hours. There was a significant increase in length of stay for patients, over 36 hours. Patients presenting to the OR between 24 and 36 hours were often delayed due to facility reasons such as OR or surgeon availability while patients presenting over 36 hours were delayed due to medical comorbidities. Of all patients in the under-24-hours group, 34.7% had an echocardiogram compared with 56.1% and 69.3%, respectively. Similarly, 17.7% of patients received cardiac clearance in the under-24-hours group, compared with 31.8% and 48%, respectively. Conclusions: The timeliness of presentation of hip fractures to the OR is a multidisciplinary effort and requires cooperation between a variety of services to increase safety and efficiency as well as to control costs.

Attachment and Growth of Fibroblasts and Tenocytes Within a Porous Titanium Scaffold: A Bioreactor Approach.

Background: Direct attachment of tendons to metallic implants is important in orthopedics. Tissue integration depends on scaffold microstructure and composition. This study evaluated the effect of pore size of titanium on the viability and function of fibroblasts and tenocytes in a dynamic bioreactor. Methods: Standardized Ti porous cylinders with 3 pore sizes (400, 700, and 1000 µm) were seeded with fibroblasts or tenocytes (4500 cells/µL) in silicon tubes. Cells were analyzed via alamarBlue (AB) assay in addition to scanning electron microscopy at day 7 (fibroblasts) or day 8 (tenocytes) and day 15. AB functions as a cell health indicator where functional living cells reduce the resazurin dye (blue) in the solution to resorufin (pink), and cell viability can be quantified via spectroscopy. Results: At day 7, fibroblasts cultured on all sizes reduced AB, with significant differences noted between 400 vs 1000 µm (P = .013) and 700 vs 1000 µm (P = .001). At day 15, fibroblasts reduced AB on all sizes with a significant difference noted between 700 vs 1000 µm (P = .004). Fibroblasts on all 3 pore sizes increased AB reduction from day 7 to day 15. Tenocytes reduced AB with significant differences between the 400 vs 700 µm (P = .049) and the 400 vs 1000 µm pore sizes at day 8. In contrast, tenocyte reduction of AB decreased from day 8 to day 15. Scanning electron microscopy performed on fibroblast cylinders showed fibroblasts reached the surface of the cylinders, confirming interconnectivity. Conclusions: While both fibroblasts and tenocytes penetrated the pores, fibroblasts preferred larger size, whereas tenocytes favored smaller size. Results are encouraging since soft-tissue attachment to a metallic scaffold is difficult but clinically desirable. Future studies could be performed in an in vivo animal model.

Osteoblastic differentiation and bactericidal activity are enhanced by erythromycin released from PCL/PLGA-PVA coaxial nanofibers.

Prosthesis with antibiotic-eluting nanofibrous (NF) coating represents coating alternative to prevent periprosthetic joint infection (PJI). In this study, four formulas of erythromycin (EM)-embedded both in core and sheath components of coaxial PCL/PLGA-PVA NF coatings were developed: EM 0 (no EM), EM 100 (100 µg/mL), EM500 (500 µg/mL) and EM1000 (1000 µg/mL). EM doping altered the physicochemical and structural properties of NFs to some extent, including the increase of NF porosity and surface wettability. A sustained EM release from EM-NFs for >4 weeks was observed. Eluents collected from EM-NFs showed strong zone of inhibition (ZOI) to Staphylococcus aureus growth and the sizes of ZOI positively related to the amount of EM released. EM-NFs were nontoxic to rat bone marrow stem cells (rBMSCs). Cell growth was significantly enhanced when comparing rBMSCs cultured on EM-NFs (EM0 and EM 100) to those cultured on NF-free control. Cell differentiation (ALP activity) was notably enhanced by EM100, compared to control and EM0. Eluents from EM-NFs on rBMSCs were also investigated. The presence of 10% EM-NF eluents inhibited the growth of rBMSCs, which was proportional to the amount of EM doped. The ALP activity was notably enhanced by eluents from EM-NFs with the highest activity in EM100 compared to control and EM0. Our data indicate that EM-doped PCL/PLGA-PVA coaxial NF coatings have a great potential to be applied as a new implant coating matrices. Further in vivo testing in animal models is currently planned that should represent the first step in predicting the clinical outcomes of EM-eluting NF coating approach.

John N. Insall Award: MARCQI's Pain-Control Optimization Pathway (POP): Impact of Registry Data and Education on Opioid Utilization.

BACKGROUND: In 2019, the Michigan Arthroplasty Registry Collaborative Quality Initiative (MARCQI) recommended an evidence-based opioid pain pathway to participating physicians and hospitals for patients undergoing total joint arthroplasty (TJA). The purpose of this study was to determine if the education could influence and have lasting effects on the prescribing patterns for TJA patients. METHODS: Using the MARCQI database, the number of oral morphine equivalents (OMEs) prescribed at discharge were collected from January 2018 through December 2019 for all primary arthroplasty procedures. Periods compared included before and after July 2018 Michigan opioid laws as well as before and after the March 2019 MARCQI recommendations. The data compared total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients, opioid-naive vs opioid-tolerant patients, individual surgeons, and MARCQI sites. RESULTS: The data included 84,998 TJAs: 22,774 opioid-naive THAs, 9124 opioid-tolerant THAs, 40,882 opioid-naive TKAs, and 12,218 opioid-tolerant TKAs. In all the groups and at all time periods there were a significant decrease in prescriptions (P < .001). Individual surgeons and participating sites also demonstrated decreased OMEs on discharge after the recommendations. Between the first and last months of collection, this represented an overall decrease of opioid OMEs for THA by 47.1% for opioid-naive patients and 53.4% for opioid-tolerant patients. For TKA patients, the OME decrease was 48.3% for opioid-naive patients, and 48.4% for opioid-tolerant patients. CONCLUSION: The MARCQI pain control optimization pathway (POP) program has been successful in drastically reducing opioid prescribing with lasting effects, which has substantially limited the overall opioid prescription burden for patients undergoing arthroplasty.

Causes of Early Hip Revision Vary by Age and Gender: Analysis of Data From a Statewide Quality Registry.

BACKGROUND: While total hip arthroplasty (THA) is extremely successful, early failures do occur. The purpose of this study was to determine the cause of revision in specific patient demographic groups at 3 time points to potentially help decrease the revision risk. METHODS: Data for cases performed between 2012 and 2018 from a statewide, quality improvement arthroplasty registry were used. The database included 79,205 THA cases and 1,433 revisions with identified etiology (1,584 in total). All revisions performed at <5 years from the primary THA were reviewed. Six groups, men/women, <65, 65-75, and >75 years, were compared at revision time points <6 months, <1 year, and <5 years. RESULTS: There were obvious and significant differences between subgroups based on demographics and time points (P < .0001). Seven hundred and fifty-six (53%) of all revisions occurred within 6 months. The most common etiologies within 6 months (756 revisions) were fracture (316, 41.8%), dislocation/instability (194, 25.7%), and infection (98, 12.9%). At this early time point, the most common revision cause was fracture for all age/gender-stratified groups, ranging from 27.6% in young men to 60% in older women. Joint instability became the leading cause for revision after 1 year in all groups. CONCLUSION: This quality improvement project demonstrated clinically meaningful differences in the reason for THA revision between gender, age, and time from surgery. Strategies based on these data should be employed by surgeons to minimize the factors that lead to revision.

Mark Coventry Award: Efficacy of Saline Wash Plus Antibiotics Doped Polyvinyl Alcohol (PVA) Composite (PVA-VAN/TOB-P) in a Mouse Pouch Infection Model.

BACKGROUND: The efficacy of saline irrigation for treatment of periprosthetic infection (PJI) is limited by the presence of contaminated medical devices. This study evaluated treatment efficacy of locally placed polyvinyl alcohol (PVA)/bioceramic composite doped with vancomycin (PVA-VAN-P) or vancomycin and tobramycin (PVA-VAN/TOB-P) after saline irrigation in a mouse pouch infection model. METHODS: Sutures were implanted into air pouches of BALB/cJ mice, then inoculated with Staphylococcus aureus. Mice were randomized into 6 groups (n = 6 each): (1) no bacteria; (2) bacteria without saline wash; (3) saline wash only; (4) saline wash + PVA-P; (5) saline wash + PVA-VAN-P, and (6) saline wash + PVA-VAN/TOB-P. After 7 days, pouches were washed with saline alone or with additional injection of 0.2 mL of the composites. Sacrifice occurred 14 days after the washout. Histology was performed on the pouch tissues and bacteria cultures on the washout fluid. RESULTS: Bacterial culture (optical density) showed that infection persisted after saline irrigation (0.10 ± 0.14) but was effectively eradicated by the addition of PVA-VAN-P (0.05 ± 0.09) and PVA-VAN/TOB-P (0.002 ± 0.003, P < .05). These effects were confirmed by histology. Importantly, no residues of the PVA-P were detected in either the pouch washouts or pouch tissues. CONCLUSION: PJI is common and problematic, and few innovations have changed clinical practice and/or outcome. Our data confirmed that the effect of saline irrigation was very limited in the presence of contaminated sutures. PVA-VAN/TOB-P was biodegradable, biocompatible, and effective in eradicating bacterial retention after saline irrigation. Application of PVA-VAN/TOB-P after saline irrigation could be an option for treatment of PJI and should be evaluated in future PJI animal models.

Impacts of compacting methods on the delivery of erythromycin and vancomycin from calcium polyphosphate hydrogel matrices.

Designing hydrogels for controlled drug delivery remains a big challenge. We developed a calcium polyphosphate hydrogel (CPP) as matrix for delivery of vancomycin (VCM) and erythromycin (EM) by unique ionic binding and physical wrapping. In this continuing study, we investigated if gel discs prepared by mechanical compaction (at 3000 psi pressure, C-discs) is superior to that of discs prepared by regular manual compaction (M-discs) for the release of VCM and EM (10 wt.%). Data demonstrated a significant reduction of burst release of VCM and EM in C-discs (1.8% and 5%, respectively) as compared to that from M-discs within 72 hr (55% and 60%, respectively, p < 0.05). In addition, C-discs significantly extended the VCM release (1500 hr) and EM (800 hr) as compared to M-discs (160 and 96 hr, respectively, p < 0.05). The VCM released from C-discs retained its bactericidal activity much longer (1500 hr) than that from M-discs (700 hr, p < 0.05). Raman Spectroscopy indicated an ionic bond of both VCM and EM with fully hydrated polyphosphate chains of CPP hydrogel matrix for both M-discs and C-discs. Micro CT showed that C-discs had much denser microstructures and less number/depth of microcracks as a result of high pressure. We propose that CPP hydrogel represents an excellent tool for the controllable and sustained delivery of VCM and EM. Extensive experiments are currently underway to evaluate the potential impacts of the modification of compaction techniques, other antibiotics, gel concentrations on the drug release, degradation behavior and infection control both in vitro and in vivo.

The Effects of Depression and Anxiety on 90-day Readmission Rates After Total Hip and Knee Arthroplasty.

BACKGROUND: Patients undergoing total joint arthroplasty have higher rates of anxiety, depression or anxiety and depression than the general population and higher costs of care, which lead to higher levels of postoperative dissatisfaction and readmission rates. We evaluated the readmission rates of patients undergoing total hip or knee arthroplasty with diagnoses of anxiety, depression, or both. METHODS: Our hospital's prospectively collected data from Michigan's statewide total joint database were reviewed from 2013 to 2018. Rates of anxiety, depression or anxiety and depression were determined based on preoperative anxiolytic or antidepressant medications using National Drug Codes. RESULTS: A total of 4107 cases were included. Of which 4.28% had a readmission within the 90-day global period, and 12% had a history of depression or anxiety or both. For the entire cohort, those on anxiolytic medication were 153% more likely to be readmitted than those not on medication (P = .017). When comparing total hip arthroplasty (THA) or total knee arthroplasty (TKA), patients taking anxiolytic medication and undergoing TKA were 120% more likely to undergo readmission within 90 days (P = .021). Patients on depression medication alone were not at increased risk of readmission in the TKA cohort (P = .991). For THA, neither diagnosis appeared a risk factor for readmission (P = .852). CONCLUSIONS: Patients with depression, anxiety, or both undergoing TKA were at a statistically significant risk of readmission within 90 days compared with patients without these diagnoses. Anxiety and depression were both risk factors for readmission, but anxiety appeared to have a more significant impact. Patients undergoing THA on the other hand did not appear to share this risk profile.

Bone morphology of the proximal femoral canal: ethnicity related differences and the influence on cementless tapered wedge stem designs.

BACKGROUND: Differences in proximal femoral morphology between ethnicities may have implications on the design of cementless tapered wedge stems. This study analyses the differences in Asian and Caucasian bone morphology as well as the related fit of various cementless tapered wedge stem designs. METHODS: A computed tomography database and modelling software was used to retrospectively analyse a total of 1345 femora. Ethnicity related comparisons as well as the fit of the stem designs were analysed. RESULTS: Statistically significant differences between canal shape of Caucasian and Japanese as well as non-Japanese Asians were observed. The fit of the stems within the femoral canal was highly dependent on the respective stem shape. CONCLUSIONS: The shape differences in stem designs had a larger influence on the fit within the femoral canal than the differences in ethnicity related to bone morphology.

Use of a Mandatory Clinical Decision Unit Reduces Readmission Rates following Total Joint Arthroplasty.

Readmission penalties have encouraged the implementation of protocols to reduce readmission rates. We hypothesized that by keeping postoperative patients, who return to the emergency department (ED) in a clinical decision unit (CDU) until being evaluated by the orthopaedic team, there would be a reduction in the readmission rate after total joint arthroplasty (TJA) at our institution. Our institution mandated the use of the CDU for all potential orthopaedic TJA readmissions. A retrospective review of prospectively collected data was performed on 365 patients who presented to the ED after either total hip arthroplasty (THA) or total knee arthroplasty (TKA). Patients presenting in the year prior to the implementation of the CDU program were compared with patients presenting in the year after implementation. Demographics, length of stay, comorbidities, and 30-day readmission rates were recorded. Additionally, a financial analysis was performed. Overall, for THA and TKA, there were a combined 141 ED visits prior to the implementation of the CDU program and 224 afterward; of these, 40 were readmitted before the CDU program and only 13 were readmitted afterward (p < 0.01). The financial analysis found that the overall 90-day cost for patients in the postoperative period was nearly $800 lower on average (p = 0.027) post-CDU implementation.During the first year of the CDU project at our institution, we significantly reduced the readmission rates following TJA and demonstrated significant cost saving. This is a Level III, prognostic study.

Risk factors for manipulation under anaesthesia after total knee arthroplasty.

AIMS: Postoperative range of movement (ROM) is an important measure of successful and satisfying total knee arthroplasty (TKA). Reduced postoperative ROM may be evident in up to 20% of all TKAs and negatively affects satisfaction. To improve ROM, manipulation under anaesthesia (MUA) may be performed. Historically, a limited ROM preoperatively was used as the key harbinger of the postoperative ROM. However, comorbidities may also be useful in predicting postoperative stiffness. The goal was to assess preoperative comorbidities in patients undergoing TKA relative to incidence of postoperative MUA. The hope is to forecast those who may be at increased risk and determine if MUA is an effective form of treatment. METHODS: Prospectively collected data of TKAs performed at our institution's two hospitals from August 2014 to August 2018 were evaluated for incidence of MUA. Comorbid conditions, risk factors, implant component design and fixation method (cemented vs cementless), and discharge disposition were analyzed. Overall, 3,556 TKAs met the inclusion criteria. Of those, 164 underwent MUA. RESULTS: Patients with increased age and body mass index (BMI) had decreased likelihood of MUA. For every one-year increase in age, the likelihood of MUA decreased by 4%. Similarly, for every one-unit increase in BMI the likelihood of MUA decreased by 6%. There were no differences in incidence of MUA between component type/design or fixation method. Current or former smokers were more likely to have no MUA. Surprisingly, patients discharged to home health service or skilled nursing facility were approximately 40% and 70% less likely than those discharged home with outpatient therapy to be in the MUA group. MUA was effective, with a mean increased ROM of 32.81° (SD 19.85°; -15° to 90°). CONCLUSION: Younger, thinner patients had highest incidence of MUA. Effect of discharge disposition on rate of MUA was an important finding and may influence surgeons' decisions. Interestingly, use of cement and component design (constraint) did not impact incidence of MUA. Level of Evidence II: Prospective cohort study. Cite this article: Bone Joint J 2020;102-B(6 Supple A):66-72.

Characterization of Pulmonary Emboli in Total Joint Arthroplasty Patients Compared to General Medical Patients.

Pulmonary emboli (PEs) occur in medical and postoperative total joint arthroplasty (TJA) patients. These are different patient populations, yet both undergo identical diagnosis and treatment regardless of PEs size and quantity. To date, there has been no analysis of the location, size, and quantity of emboli that occur postoperatively in TJA compared with general medical patients. We hypothesized TJA patients would have different size and distribution of PEs per event compared with medical patients. A retrospective chart review was conducted of patients who underwent total hip or knee arthroplasty in comparison to general medical patients at our institution from 2006 to 2011 with a PE diagnosis. Medical co-morbidities, sex, age, procedure, postoperative day, size, and location of PE using spiral computed tomography were recorded using a novel mapping scheme. Embolus size was defined based on blockage level in the pulmonary arterial tree. Of the 4,178 TJA patients reviewed, 51 were diagnosed with a PE. A total of 67% of TJA patients were women, yet women represented 90% (n = 46) of TJA PE patients (p < 0.0001). Medical patients had an equal distribution of men and women with PEs. Orthopaedic patients averaged more (4.0 vs. 2.2, p < 0.0001) and smaller PEs compared with medical patients (p < 0.0001). In conclusion, women undergoing TJA had significantly higher risk of developing PE compared with male arthroplasty or medical patients. Differences were observed in size and distribution of PEs between medical and TJA patients, which suggest a different nature of embolic phenomenon.

Long-Term Sustainability of a Quality Initiative Program on Transfusion Rates in Total Joint Arthroplasty: A Follow-Up Study.

BACKGROUND: There are significant variations in transfusion rates among institutions performing total joint arthroplasty. We previously demonstrated that implementation of an educational program to increase awareness of the American Association of Blood Banks' transfusion guidelines led to an immediate decrease in transfusion rates at our facilities. It remained unclear how this initiative would endure over time. We report the long-term success and sustainability of this quality program. METHODS: We reviewed the Michigan Arthroplasty Collaborative Quality Initiative data from 2012 through 2017 of all patients undergoing primary hip and knee arthroplasty at our institutions for preoperative and postoperative hemoglobin level, transfusion status, and number of units transfused and transfusions outside of protocol to identify changes surrounding our blood transfusion educational initiative. We calculated the transfusions prevented and cost implications over the course of the study. RESULTS: We identified 6645 primary hip and knee arthroplasty patients. There was a significant decrease in transfusion rate and overall transfusions in each group when compared to pre-education values. Subgroup analysis of TKA and THA independently showed significant decreases in both transfusion rate and overall transfusions. Over the final 3 years of the study, only 2 patients were transfused outside of the American Association of Blood Banks protocol. We estimate prevention of 519 transfusions over the study period. CONCLUSION: Application of this quality initiative was an effective means of identifying opportunities for quality improvement. The program was easily initiated, had significant early impact, and has been shown to be sustainable.

The Effect of Ambient Temperature and Implantation Time on the Material Properties of Two Viscosity-Differing Cements Using American Society of Testing and Materials Methodology.

Ambient temperature and time to implantation can affect the material properties of polymethylmethacrylate bone cement, and cement intrusion depth has been shown to affect implant fixation. The purpose of this study was to examine the effects of ambient temperature and time to implantation on depth of intrusion, and the effect of ambient temperature on setting time. Two types of cements were evaluated: cement A (Simplex P,medium Q7 viscosity) and cement B (Palacos R, high viscosity). Dough, working and setting times were determined, as well as intrusion depth, at different temperatures per American Society of Testing and Materials (ASTM) protocol F451. A vacuum mixer was used in a temperature- and humidity-controlled environment at 60, 65, and 70°F. At each temperature, the cement was placed into an intrusion mold at 0, 50, and 100% of working time. Increasing ambient temperature resulted in a significant decrease in dough and working and setting times for both cements (p = 0.038 - < 0.001). At each working time point and temperature, cement A showed significantly more intrusion than cement B (p = 0.044 - < 0.001). There was no effect of temperature on intrusion depth regardless of working time to implantation for either cement with the exception of cement B when comparing 60 versus 70°F at 0% working time (p = 0.004). Both cements showed a significant decrease in intrusion as time to implantation increased (p < 0.001). In conclusion, there are large inherent differences in properties of commercially available cements, and these properties are affected by such variables as time to implantation and ambient temperatures. An understanding of these properties may aid the surgeon in optimizing surgical outcomes.