Commercial Synovial Antigen Testing is Inferior to Traditional Culture for the Diagnosis of Periprosthetic Joint Infection in Patients Undergoing Revision Total Knee Arthroplasty.

BACKGROUND: Despite its limitations, a culture remains the "gold standard" for pathogen identification in patients who have periprosthetic joint infection (PJI). Recently, a synovial fluid antigen test has been introduced by a commercial entity. The purpose of this multicenter study was to determine the accuracy of the antigen test in the diagnosis of PJI. METHODS: This retrospective study identified 613 patients undergoing revision total knee arthroplasty who had undergone preoperative synovial fluid analysis. A PJI was defined using the 2018 International Consensus Meeting (ICM) criteria. Patients who had an extended period (> 180 days) from aspiration to revision procedure (n = 62), those presenting within 90 days of their index arthroplasty procedure (n = 17), and patients who had an inconclusive ICM score (n = 8) were excluded. Using receiver operator characteristic curve analyses, we examined the utility of the microbial identification (MID) antigen test and any positive culture (either preoperative or intraoperative) in the diagnosis of PJI. RESULTS: A total of 526 patients were included. Of these, 125 (23.8%) were ICM positive and 401 (76.2%) were ICM negative. Culture demonstrated an area under the curve (AUC) of 0.864, sensitivity of 75.2%, and specificity of 97.5%. On the other hand, the MID test exhibited an AUC of 0.802, sensitivity of 61.6%, and specificity of 98.8%. The AUC of culture was significantly higher than that of the MID test (P = .037). The MID test was positive in 41.9% of culture-negative PJI cases. We also observed a high rate of discordance (29.7%) when both culture and the MID test were positive in the ICM-positive group. CONCLUSIONS: Synovial fluid antigen testing does not provide additional clinical benefit when compared to traditional cultures for the diagnosis of PJI. The antigen test had low sensitivity in the diagnosis of PJI and a relatively high rate of discordance with culture. LEVEL OF EVIDENCE: Level III.

Prevalence of Depressive Symptoms in Aseptic Revision Total Knee Arthroplasty Based on the Mode of Failure.

Background: Complications following total knee arthroplasty (TKA) that necessitate revision cause considerable psychological distress and symptoms of depression, which are linked to poorer postoperative outcomes, increased complications, and increased healthcare utilization. We aimed to identify the prevalence of mental health disorders and symptoms preoperatively and postoperatively in patients undergoing aseptic revision TKA and to stratify these patients based on their mechanism of failure. Methods: All patients undergoing aseptic revision TKA from 2008 to 2019 with a minimum 1-year follow-up were retrospectively reviewed at a single institution. Patients (n = 394) were grouped based on 7 failure modes previously described. Patients were considered to have depressive symptoms if their Veterans RAND-12 mental component score was below 42. Preoperative and postoperative Veterans RAND-12 mental component scores at the latest follow-up were evaluated. Results: Overall comparative prevalence of preoperative to postoperative depressive symptoms was 23.4%-18.8%. By mode of failure are as follows: arthrofibrosis (25.8%-16.7%), aseptic loosening (25.3%-18.9%), extensor mechanism disruption (25%-50%), failed unicompartmental knee arthroplasty (8.6%-14.3%), instability (25.7%-17.1%), osteolysis or polyethylene wear (23.1%-23.1%), and patellar failure (11.8%-23.5%). There was no difference in depressive symptoms among failure modes preoperatively (P = .376) or at the latest postoperative follow-up (P = .175). Conclusions: The prevalence of depressive symptoms in revision TKA patients appears to be independent of failure mode. Surgeon awareness and screening for depressive symptoms in this patient population preoperatively with referral for potential treatment may improve early postoperative outcomes.

Joint aspiration for diagnosis of chronic periprosthetic joint infection: when, how, and what tests?

Diagnosing chronic periprosthetic joint infection (PJI) requires clinical suspicion in combination with both serological and synovial fluid tests, the results of which are generally applied to validated scoring systems or consensus definitions for PJI. As no single "gold standard" test exists, the diagnosis becomes challenging, especially in the setting of negative cultures or equivocal test results. This review aims to address the workup of chronic PJI and considerations for clinical evaluation to guide treatment. Following aspiration of the joint in question, a multitude of tests has been developed in an attempt to assist with diagnosis, including cell synovial white blood cell count, gram stain, cultures, leukocyte esterase, alpha-defensin, synovial C-reactive protein, multiplex polymerase chain reaction, next-generation sequencing, and interleukins. Each test has advantages and disadvantages and should be used in conjunction with the overall clinical picture to guide further clinical evaluation and treatment in this complex patient population.

Increased Dislocation Rates After Total Hip Arthroplasty in Patients With Prior Isolated Sacroiliac Joint Arthrodesis.

BACKGROUND: While stiffness of the lumbosacral spine is a known predictor of instability following total hip arthroplasty (THA), little is known about the medical- and surgical-related outcomes following THA in patients who have prior isolated sacroiliac (SI) joint arthrodesis. METHODS: 197 patients who had a history of isolated SI joint arthrodesis who subsequently underwent elective primary THA for a diagnosis of osteoarthritis (THA-SI) from 2015 to 2021 were identified in a national administrative database. Using propensity score matching and logistic regression analyses, this cohort was compared to two groups of patients: patients who did not have any history of lumbar or SI arthrodesis and patients undergoing primary THA who had a history of lumbar arthrodesis without extension into the SI joint (THA-LF). RESULTS: The THA-SI group had a significantly higher incidence of dislocation (odds ratio 2.06, 95% confidence interval 1.04-4.04, P = .037) with no increased incidence of medical complications or other surgical complications when compared to patients without a history of SI or lumbar arthrodesis. There were no significant differences in any complications in THA-SI patients when compared to THA-LF patients. CONCLUSION: Patients who had prior isolated SI joint arthrodesis undergoing primary THA demonstrated a two-fold increased incidence of dislocation when compared to those who did not have prior SI arthrodesis, although the risk of complications in this population was similar to that observed in patients who had prior isolated lumbar spine arthrodesis.

Total Hip Arthroplasty in Patients Who Have Respiratory Disease Who use Supplemental Home Oxygen.

BACKGROUND: The purpose of this study is to investigate the association between supplemental home oxygen prior to surgery and both medical and surgical complications after primary elective total hip arthroplasty (THA) in patients who have respiratory disease (RD). METHODS: The Mariner database was used to identify patients who have RD who received primary elective THA from 2010 to 2020. The THA patient cohorts consisted of 20,872 patients who had RD prescribed home oxygen and 69,520 patients who had RD without home oxygen. For patients who had a diagnosis of RD and were prescribed supplemental home oxygen (O2) and those who were not, the rates of postoperative medical and surgical complications, hospital readmissions, and emergency room visits were determined. Reimbursements and lengths of stay were also determined. Logistic regression analyses were utilized to compare both cohorts to matched cohorts without RD, as well as to each other directly. RESULTS: In comparison to the matched control group, the RD with home oxygen group had a significantly higher rate of pneumonia (odds ratio [OR] 4.27, P < .0001), pulmonary embolism (OR 1.81, P < .0001), periprosthetic joint infection (OR 1.21, P < .0001), and periprosthetic fracture (OR 1.81, P = .001). The RD with home oxygen cohort also had a significantly higher incidence of pneumonia (OR 2.16, P < .0001), periprosthetic joint infection (OR 1.38, P < .0001), and periprosthetic fracture (OR 1.24, P = .009) compared to RD patients who did not have home oxygen. CONCLUSION: Supplemental home oxygen use prior to surgery is associated with a significantly higher risk of postoperative medical and surgical complications after elective THA.

Osteopetrosis is Associated With an Increased Risk for Intraoperative Periprosthetic Fracture in Total Hip Arthroplasty but not in Total Knee Arthroplasty.

BACKGROUND: Osteopetrosis is a rare, inherited disorder in which bone remodels to become pathologically dense. There has been a paucity of data evaluating medical and surgical complications following total hip arthroplasty (THA) and total knee arthroplasty (TKA) in this patient population. The objective of this study was to evaluate osteopetrosis as a potential risk factor for medical and surgical complications following THA and TKA. METHODS: Patients who had a diagnosis of osteopetrosis and underwent THA or TKA from 2010 to 2020 were identified in a national database. A total of 534 THA and 972 TKA patients who had osteopetrosis were identified and compared with matched cohorts of 2,670 and 4,860 patients, respectively. The rates of postoperative medical and surgical complications, hospital readmissions, and emergency room visits were calculated. In addition, reimbursements and lengths of stay were determined. Osteopetrosis patients were then compared to a 5:1 matched cohort without osteopetrosis using logistic regression analyses to control for additional confounding factors. RESULTS: The osteopetrosis THA group had a substantially higher incidence of intraoperative periprosthetic fracture compared to the matched cohort (1.12% versus 0.19%, Odds Ratio 5.88, P = .005). Patients who had a history of osteopetrosis were not found to be at a significantly increased risk for other investigated medical or surgical complications compared to matched controls following THA or TKA. CONCLUSION: Patients who had a history of osteopetrosis undergoing elective primary THA are associated with a significantly increased risk for intraoperative periprosthetic fracture. Patients with a history of osteopetrosis undergoing elective primary TKA were not found to be at an increased risk for any of the investigated complications.

Use of Supplemental Home Oxygen is Associated With Early Postoperative Complications Following Total Knee Arthroplasty.

BACKGROUND: The objective of this study is to evaluate preoperative supplemental home oxygen use as a potential risk factor for both medical and surgical complications following primary elective total knee arthroplasty (TKA) in patients who have respiratory disease (RD). METHODS: Patients with a diagnosis of RD who underwent elective TKA from 2010 to 2020 were identified using a national database. The rates of postoperative medical and surgical complications, hospital readmissions, and emergency room visits were calculated for RD patients who used supplemental home oxygen and those who did not. Additionally, reimbursements and lengths of stay were determined. Both cohorts were then compared to matched cohorts who did not have RD using logistic regression analyses. RESULTS: A total of 41,418 patients who underwent TKA with RD on home oxygen and 138,635 patients who had RD without home oxygen use were compared with matched cohorts. The RD cohort with home oxygen use had a significantly higher incidence of periprosthetic joint infection (5.78% versus 2.69%, odds ratio [OR] 1.42, P < .0001), pneumonia (3.95% versus 0.69%, OR 4.44, P < .0001), venous thromboembolism (3.17% versus 2.10%, OR 1.12, P = .007), and periprosthetic fracture (0.82% versus 0.34%, OR 1.72, P < .0001) compared to the matched control cohort. Additionally, the RD with home oxygen cohort had a significantly higher incidence of periprosthetic joint infection (5.78% versus 3.77%, OR 1.15, P < .0001), pneumonia (3.95% versus 1.63%, OR 1.99, P < .0001), and several other medical complications compared to RD patients without home oxygen use. CONCLUSION: Preoperative supplemental home oxygen use is associated with significantly increased risk of postoperative surgical and medical complications following elective TKA. This finding can help guide risk assessment and the informed consent process prior to surgery.

Outcomes following Total Hip Arthroplasty for Femoral Head Osteonecrosis in Patients with History of Solid Organ Transplant.

BACKGROUND: Osteonecrosis of the femoral head (ONFH) is a potentially debilitating condition, often requiring total hip arthroplasty (THA). Patients with solid organ transplant (SOT) are at increased risk of postoperative complications after THA for osteoarthritis. The objective of the present study is to evaluate SOT as a potential risk factor for complication after THA for ONFH. METHODS: This is a retrospective study that identified patients with SOT who underwent THA for ONFH from 2005 to 2014 in a national insurance database and compared them to 5:1 matched controls without transplant. Subgroup analyses of patients with renal transplant (RT) and those with non-RT were also analyzed. A logistic regression analysis was used to compare rates of mortality, hospital readmission, emergency room (ER) visits, infection, revision, and dislocation while controlling for confounders. Differences in hospital charges, reimbursement, and length of stay (LOS) were also compared. RESULTS: 996 patients with SOT who underwent THA were identified and compared to 4,980 controls. SOT patients experienced no increased risk of early postoperative complications compared to controls. Solid organ transplant was associated with higher resource utilization and LOS. Renal transplant patients were found to have significantly higher risk of hospital readmission at 30 days (odds ratio [OR] 1.77; p = 0.001) and 90 days (OR 1.62; p < 0.001) and hospital LOS (p < 0.001), but had lower risk of infection (OR 0.65; p = 0.030). Non-RT patients had higher rate of ER visits at 30 days (OR 2.26; p = 0.004) but lower rates of all-cause revision (OR 0.22; p = 0.043). CONCLUSIONS: Patients with history of SOT undergoing THA for ONFH utilize more hospital resources with longer LOS and greater risk of readmission but are not necessarily at an increased risk of early postoperative complications.

Outcomes Following Total Hip Arthroplasty for Osteonecrosis of the Femoral Head in Patients on Hemodialysis.

BACKGROUND: Osteonecrosis of the femoral head (ONFH) is a potentially debilitating condition, often requiring total hip arthroplasty (THA). Patients on hemodialysis (HD) are at increased risk for complications after THA for osteoarthritis, however there is limited information on outcomes of THA for ONFH in patients on HD. With increasing prevalence of chronic kidney disease (CKD) requiring HD, studies are needed to characterize the risk of complications in these patients. Therefore, the purpose of this study was to evaluate HD as a potential risk factor for complication after THA in patients with ONFH on HD. METHODS: Patients on HD with ONFH who underwent THA with at least 2 years of follow-up were identified using a combination of ICD-9 and CPT codes in a national insurance database. A 10:1 matched control cohort of patients with ONFH not on HD was created for comparison. A logistic regression analysis was used to evaluate rates of death, hospital readmission, emergency room (ER) visit, infection, revision, and dislocation between cohorts. Differences in hospital charges, reimbursement, and length of stay between the two groups were also assessed. RESULTS: One thousand one hundred thirty-seven patients on HD who underwent THA for ONFH were compared to a matched control cohort of 11,182 non-HD patients who underwent THA for ONFH. Patients on HD experienced higher rates of death (HD 4.1%, non-HD 0.9%; odds ratio [OR] 3.35, p < 0.01), hospital readmission (HD 16.1%, non-HD 5.9%; OR 2.69, p < 0.01) and ER visit (HD 10.4%, non-HD 7.4% OR 1.5, p < 0.01). Hemodialysis was not associated with higher risk of infection, revision, or dislocation, but was associated with significantly higher charges (p < 0.01), reimbursement (p < 0.01), and hospital length of stay (p < 0.01). CONCLUSIONS: While patients on HD do not have increased risk of implant-related complications, they are at increased risk of developing medical complications following THA for ONFH and subsequently may require more resources. Orthopedic surgeons and nephrologists should be cognizant of the increased risk in this population to provide appropriate preoperative counseling and enhanced perioperative medical management. LEVEL OF EVIDENCE: Therapeutic Level III.

The 2021 Association Research Circulation Osseous Classification for Early-Stage Osteonecrosis of the Femoral Head to Computed Tomography-Based Study.

BACKGROUND: The Association Research Circulation Osseous developed a novel classification for early-stage (precollapse) osteonecrosis of the femoral head (ONFH). We hypothesized that the novel classification is more reliable and valid when compared to previous 3 classifications: Steinberg, modified Kerboul, and Japanese Investigation Committee classifications. METHODS: In the novel classification, necrotic lesions were classified into 3 types: type 1 is a small lesion, where the lateral necrotic margin is medial to the femoral head apex; type 2 is a medium-sized lesion, with the lateral necrotic margin being between the femoral head apex and the lateral acetabular edge; and type 3 is a large lesion, which extends outside the lateral acetabular edge. In a derivation cohort of 40 early-stage osteonecrotic hips based on computed tomography imaging, reliabilities were evaluated using kappa coefficients, and validities to predict future femoral head collapse by chi-squared tests and receiver operating characteristic curve analyses. The predictability for future collapse was also evaluated in a validation cohort of 104 early-stage ONFH. RESULTS: In the derivation cohort, interobserver reliability (k = 0.545) and intraobserver agreement (63%-100%) of the novel method were higher than the other 3 classifications. The novel classification system was best able to predict future collapse (P < .05) and had the best discrimination between non-progressors and progressors in both the derivation cohort (area under the curve = 0.692 [0.522-0.863], P < .05) and the validation cohort (area under the curve = 0.742 [0.644-0.841], P = 2.46 × 10-5). CONCLUSION: This novel classification is a highly reliable and valid method of those examined. Association Research Circulation Osseous recommends using this method as a unified classification for early-stage ONFH. LEVEL OF EVIDENCE: Level III, diagnostic study.

Increased Reimbursement for Surgical Fixation of Hip Fractures: The Difference Between the Hospital and the Surgeon.

OBJECTIVES: To evaluate trends and variations in hospital charges and payments relative to surgeon charges and payments for surgical treatment of hip fractures in the US Medicare population. METHODS: Hospital and surgeon charges and payments after treatment of hip fractures by closed reduction and percutaneous pinning (CRPP), open reduction internal fixation (ORIF), or intramedullary nail (IMN), along with corresponding patient demographics, 90-day and 1-year mortality, Charlson Comorbidity Index (CCI), and length of stay (LOS) from 2005 to 2014 were captured from the 5% Medicare Standard Analytic Files. The ratio of hospital to surgeon charges (CM: Charge Multiplier) and the ratio of hospital to surgeon payments (PM: Payment Multiplier) were calculated for each year and region of the United States and trended over time. Correlations between the CM and PM and LOS were evaluated using a Pearson correlation coefficient (r). RESULTS: Three thousand twenty-eight patients who underwent CRPP and 25,341 patients who underwent ORIF/IMN were included. The CM for CRPP increased from 10.1 to 15.6, P < 0.0001. The CM for ORIF/IMN increased from 11.9 to 17.2, P < 0.0001. The PM for CRPP increased from 15.1 to 19.2, P < 0.0001. The PM for ORIF/IMN increased from 11.5 to 17.4, P < 0.0001. CONCLUSIONS: Hospital charges and payments have continually increased relative to surgeon charges and payments for treatment of hip fractures despite decreasing LOS.

Reimbursements for Revision Total Hip Arthroplasty Have Increased for Hospitals but Not for Surgeons.

BACKGROUND: With increases in total hip arthroplasty procedures the need for revision total hip arthroplasty (rTHA) has increased as well. This study aims to analyze the trends in hospital charges and payments relative to corresponding surgeon charges and payments in a Medicare population for rTHA for aseptic revisions, stage 1 and stage 2 revisions. METHODS: The 5% Medicare sample database was used to capture hospital and surgeon charges and payments related to 4449 patients undergoing aseptic revision, 517 for stage 1 revision, and 300 for stage 2 revision in between the years 2004 and 2014. Two values were calculated: (1) the ratio of hospital to surgeon charges (CM) and (2) the ratio of hospital to surgeon payments (PM). Year-to-year variation and trends in patient demographics, Charlson Comorbidity Index (CCI), length of stay (LOS), CM, and PM were evaluated. RESULTS: The mean CCI for aseptic revisions and stage 1 revisions did not significantly change (P < .088 and P < .063). The CCI slightly increased for stage 2 revisions (P < .04). The mean LOS decreased significantly over time in all 3 procedure types. The CM increased by 39% (P < .02) in aseptic revisions, 109% in stage 1 revisions (P < .001) but did not significantly change in stage 2 revisions (P < .877). PM for aseptic revisions increased around 103% (P < .001), 107% for stage 1 revisions (P < .001), and 9.7% for stage 2 revisions (P < .176). CONCLUSION: Hospital charges and payments relative to surgeon charges and payments have increased substantially for THA aseptic revisions, stage 1 revisions, and stage 2 revisions despite stable patient complexity and decreasing LOS.

Prior Nonarthroplasty Surgery Increases Risk of Complication in Primary Total Knee Arthroplasty.

BACKGROUND: Prior ipsilateral knee surgery may increase the risk for complications after total knee arthroplasty (TKA). It remains unclear if the extent of previous surgery affects those risks disparately. The purpose of this study is to evaluate prior nonarthroplasty bony procedure (BP) and soft tissue only procedure (STP) as a potential risk factor for complications after TKA and determine the association with charges or reimbursement of the primary TKA. METHODS: Patients who underwent primary TKA with previous knee surgery were identified using a national Medicare database and matched 1:5 to controls without prior knee surgery. Rates of postoperative medical and surgical complications were calculated in addition to hospital-associated charges and reimbursements. Logistic regression analysis was used to control for confounding factors. RESULTS: Patients who underwent BP (n = 835) had increased risk of readmission (58.6% vs 45.3%, odds ratio (OR) 1.72, 95% confidence interval (CI) 1.59-1.85, P < .001) and emergency room visits (14.5% vs 10.4%, OR 1.44, 95% CI 1.29-1.61, P = .001). Patients who underwent STP (n = 6766) had increased risk of readmission (58.1% vs 45.2%, OR 1.69, 95% CI 1.64-1.73, P < .001), emergency room visits (12.6% vs 0.7%, OR 1.33, 1.28-1.39, P < .001), revision (1.8% vs 1.4%, OR 1.33, 95% CI 1.21-1.47, P = .006), cerebrovascular accident (2.3% vs 1.7%, OR 1.33, 95% CI 1.22-1.46, P = .002), and venous thromboembolism (3.8% vs 3.2%, OR 1.21, 95% CI 1.13-1.29, P = .009). Prior surgery was associated with increased charges and reimbursements. CONCLUSION: Prior ipsilateral knee surgery is associated with significantly increased risks of postoperative complications after primary TKA. Interestingly, previous STP but not BP increased the risk of short-term revision and venous thromboembolism.

Trends in Hospital and Surgeon Charges and Reimbursements for Revision Total Knee Arthroplasty.

BACKGROUND: The relationship between surgeon and hospital charges and reimbursements for revision total knee arthroplasty (TKA) has not been well examined. The objective of this study is to report trends and variations in hospital charges and payments compared to surgeons for stage 1 (S1) vs stage 2 (S2) septic revision TKA and aseptic revision (AR) TKA. METHODS: The 5% Medicare sample was used to capture hospital and surgeon data for revision TKA from 2005 to 2014. The charge multiplier (CM) and ratio of hospital to surgeon charges, and the payment multiplier (PM) and ratio of hospital to surgeon payments were calculated. Year-to-year variation and regional trends in-patient demographics, Charlson Comorbidity Index, length of stay (LOS), CM, and PM were evaluated. RESULTS: In total, 4570 AR, 1323 S1, and 863 S2 TKA patients were included. CM increased for all cohorts: 8.1-13.8 for AR (P < .001), 21.0-22.5 (P = .07) for S1, and 11.8-22.0 (P < .001) for S2. PM followed a similar trend, increasing 8.1-13.8 (P < .001) for AR, 19.8-27.3 (P = .005) for S1, and 14.7-30.7 (P < .001) for S2. Surgeon reimbursement decreased for all cohorts. LOS decreased for AR (3.8-2.8 days), S1 (12.8-6.9 days), and S2 (4.5-3.9 days). Charlson Comorbidity Index remained stable for AR patients but increased significantly for S1 and S2 cohorts. CONCLUSION: Hospital charges and payments relative to the surgeons have significantly increased for revision TKA in the setting of stable or increasing patient complexity and decreasing LOS.

Iron Deficiency Anemia is Associated with Increased Early Postoperative Surgical and Medical Complications Following Total Hip Arthroplasty.

BACKGROUND: Iron deficiency anemia (IDA) is a medical comorbidity commonly diagnosed in those undergoing primary total hip arthroplasty (THA). The authors sought to evaluate IDA as a risk factor for early postoperative complications following discharge and describe the hospital resource utilization of this patient population. METHODS: Patients with a diagnosis of IDA who underwent THA from 2005 to 2014 were identified in a national insurance database. The rates of postoperative medical complications and surgery-related complications, as well as hospital readmission, emergency department visits, and death were calculated. Additionally, 90-day and day of surgery cost and length of stay were calculated. IDA patients were then compared to a 4:1 matched control population without IDA using a logistic regression analysis to control for confounding factors. RESULTS: In total, 98,681 patients with a preoperative diagnosis of IDA who underwent THA were identified and compared to 386,724 controls. IDA was associated with increased risk of 30-day emergency department visits (odds ratio [OR] 1.35, P < .001) and 30-day readmission (OR 1.49, P < .001). IDA was also associated with an increased 90-day medical complication rate (cerebrovascular accident OR 1.11, P = .003; urinary tract infection OR 1.14, P < .001; acute renal failure OR 1.24, P < .001; transfusion OR 1.40, P < .001), as well as 1-year periprosthetic joint infection (OR 1.27, P < .001), revision (OR 1.22, P < .001), dislocation (OR 1.25, P < .001), and fracture (OR 1.43, P < .001). Patients with IDA accrued higher hospital charges ($27,658.27 vs $16,709.18, P < .001) and lower hospital reimbursement ($5509.90 vs $3605.59, P < .001). CONCLUSION: Patients with preoperative IDA undergoing THA are at greater risk of experiencing early postoperative complications and have greater utilization of hospital resources.

Are Patients More Susceptible to Viral Illness Immediately Following Hip and Knee Arthroplasty? An Analysis of Influenza Diagnoses Using Multiple Administrative Databases.

BACKGROUND: Elective surgery elicits a systemic immune response and may result in transient immunosuppression in certain patients. It is currently unknown whether patients are at increased risk for viral infection and associated illness in the immediate postoperative period following total joint arthroplasty (TJA). METHODS: Four large administrative datasets (Medicare 5% and 100% standard analytic files, Humana claims, and Mariner Database) were analyzed to identify patients who underwent total knee arthroplasty (TKA) and total hip arthroplasty (THA) from 2005 to 2017. The influenza vaccination status of each patient was defined using the presence or absence of a code for vaccination. The incidence of an influenza diagnosis was recorded in both vaccinated and unvaccinated patients during peak influenza season following the date of surgery and compared to a cohort of vaccinated patients who did not undergo surgery. RESULTS: The incidence of postoperative influenza diagnoses in TKA and THA patients was similar to that of vaccinated patients who did not undergo TJA at all time points. The results were largely consistent across all datasets. CONCLUSION: Large administrative databases fail to show an increased incidence of influenza in patients who have recently undergone TJA. While the lack of signal in the data is reassuring, these findings are limited by the nature of large administrative datasets and the accuracy of coding for influenza. Further studies will be necessary to fully understand an individual patient's postoperative risk for contracting a viral illness. LEVEL OF EVIDENCE: Level III.

Functional Flexion Instability After Rotating-Platform Total Knee Arthroplasty.

BACKGROUND: We sought to define "at risk" loading conditions associated with rotating-platform total knee arthroplasty (TKA-RP) implants that predispose to insert subluxation and spinout and to quantify tolerances for flexion-extension gap asymmetry and laxity in order to prevent these adverse events. METHODS: Biomechanical testing was performed on 6 fresh-frozen cadaveric limbs with a TKA-RP implant with use of a gap-balancing technique, followed by sequential femoral component revision with variable-thickness polyethylene inserts to systematically represent 5 flexion-extension mismatch and asymmetry conditions. Each configuration was subjected to mechanical loading at 0°, 30°, and 60°. Rotational displacement of the insert on the tibial baseplate, lateral compartment separation, and insert concavity depth were measured with use of a digital caliper. Yield torque, a surrogate for ease of insert rotation and escape of the femoral component, was calculated with use of custom MATLAB code. RESULTS: Design-intended insert rotation decreased with increasing knee flexion angles in each loading configuration. Likewise, yield torque increased with increasing joint flexion and decreased with increasing joint laxity in all testing configurations. Insert instability and femoral condyle displacement were reproduced in positions of increasing knee flexion and asymmetrical flexion gap laxity. The depth of lateral polyethylene insert concavity determined femoral condylar capture and defined a narrow tolerance of <2 mm in the smallest implant sizes for flexion gap asymmetry leading to rotational insert instability. CONCLUSIONS: Decreased femoral-tibial articular surface conformity with increasing knee flexion and asymmetrical flexion gap laxity enable paradoxical motion of the femoral component on the upper insert surface rather than the undersurface, as designed. CLINICAL RELEVANCE: Mobile-bearing TKA-RP is a technically demanding procedure requiring a snug symmetrical flexion gap. As little as 2 mm of asymmetrical lateral flexion laxity can result in decreased conformity, condyle liftoff, and insert subluxation. Flexion beyond 30° decreases bearing surface contact area and predisposes to reduced insert rotation and mechanical malfunction.

Hospital and Surgeon Reimbursement Trends for Femoral Neck Fractures Treated With Hip Hemiarthroplasty and Total Hip Arthroplasty.

BACKGROUND: The economic impact of hip fractures on the health care system continues to rise with continued pressure to reduce unnecessary costs while maintaining quality patient care. This study aimed to analyze the trend in hospital charges and payments relative to surgeon charges and payments in a Medicare population for hip hemiarthroplasty and total hip arthroplasty (THA) for femoral neck fracture. METHODS: The 5% Medicare sample database was used to capture hospital and surgeon charges and payments related to 32,340 patients who underwent hemiarthroplasty and 4323 patients who underwent THA for femoral neck fractures between 2005 and 2014. Two values were calculated: (1) charge multiplier (CM, ratio of hospital to surgeon charges), and (2) payment multiplier (PM, ratio of hospital to surgeon payments). Year-to-year variation and regional trends in patient demographics, Charlson Comorbidity Index (CCI), length of stay (LOS), 90-day and 1-year mortality, CM, and PM were evaluated. RESULTS: Hospital charges were significantly higher than surgeon charges and increased substantially for hemiarthroplasty (CM of 13.6 to 19.3, P < .0001) and THA (CM of 9.8 to 14.9, P = .0006). PM followed a similar trend for both hemiarthroplasty (14.9 to 20.2; P = .001) and THA (11.9 to 17.4; P < .0001). LOS decreased significantly for hemiarthroplasty (3.78 to 3.37d; P < .0001) despite increasing CCI (6.36 to 8.39; P = .018), whereas both LOS (3.71 to 3.79 days; P = .421) and CCI (5.34 to 7.08; P = .055) remained unchanged for THA. CONCLUSION: Hospital charges and payments relative to surgeon charges and payments have increased substantially for hemiarthroplasty and THA performed for femoral neck fractures.

Risk of Prosthetic Joint Infection Increases Following Early Aseptic Revision Surgery of Total Hip and Knee Arthroplasty.

BACKGROUND: It is important to identify risk factors for periprosthetic joint infection (PJI) following total joint arthroplasty in order to mitigate the substantial social and economic burden. The objective of this study is to evaluate early aseptic revision surgery as a potential risk factor for PJI following total hip (THA) and total knee arthroplasty (TKA). METHODS: Patients who underwent primary THA or TKA with early aseptic revision were identified in 2 national insurance databases. Control groups of patients who did not undergo revision were identified and matched 10:1 to study patients. Rates of PJI at 1 and 2 years postoperatively following revision surgery were calculated and compared to controls using a logistic regression analysis. RESULTS: In total, 328 Medicare and 222 Humana patients undergoing aseptic revision THA within 1 year of index THA were found to have significantly increased risk of PJI at 1 year (5.49% vs 0.91%, odds ratio [OR] 5.61, P < .001 for Medicare; 7.21% vs 0.68%, OR 11.34, P < .001 for Humana) and 2 years (5.79% vs 1.10%, OR 4.79, P < .001 for Medicare; 8.11% vs 1.04%, OR 9.05, P < .001 for Humana). Similarly for TKA, 190 Medicare and 226 Humana patients who underwent aseptic revision TKA within 1 year were found to have significantly higher rates of PJI at 1 year (6.48% vs 1.16%, OR 7.69, P < .001 for Medicare; 6.19% vs 1.28%, OR 4.89, P < .001 for Humana) and 2 years (8.42% vs 1.58%, OR 6.57, P < .001 for Medicare; 7.08% vs 1.50%, OR 4.50, P < .001 for Humana). CONCLUSION: Early aseptic revision surgery following THA and TKA is associated with significantly increased risks of subsequent PJI within 2 years.

Urinary Self-Catheterization is Not Associated with Increased Risk of Major Complications Following Total Hip and Knee Arthroplasty.

BACKGROUND: The objective of this study is to evaluate urinary self-catheterization as a potential risk factor for postoperative complications following total hip (THA) and knee (TKA) arthroplasty procedures. METHODS: Self-catheterization patients who underwent total joint arthroplasty from 2005 to 2014 were identified in a national insurance database. Rates of death, hospital readmission, emergency room visit, infection, revision, and dislocation for THA or arthrofibrosis for TKA were calculated, as well as cost and length of stay. Self-catheterizing patients were then compared to a 4:1 matched control cohort using a logistic regression analysis to control for confounding factors. RESULTS: Sixty-nine patients underwent THA, and 128 patients who underwent TKA and who actively self-catheterized at the time of surgery were identified. Self-catheterization was not associated with infection, emergency room visits, readmissions, revision surgery, arthrofibrosis, or cost compared to the 4:1 matched control cohort. However, self-catheterization was associated with significantly longer length of stay (difference for THA = 1.91 days, confidence interval = 0.97-2.86, P < .001; difference for TKA = 0.61, odds ratio = 0.16-1.06, P = .01). CONCLUSION: Self-catheterization does not appear to be associated with increased risk of major complications following total joint arthroplasty with the numbers available in this study. Reassurance can be given regarding concerns for infection and other complications following surgery in this patient population.