Incidence and Risk Factors for Acid-fast Bacillus/Fungal Culture Positivity in Primary, Conversion, and Revision Hip and Knee Arthroplasty.

INTRODUCTION: Previous literature has reported minimal incidences of positive fungal/AFB cultures, questioning the routine use of these tests. With growing concern for excessive use, predictive factors for patients at higher risk for intraoperative AFB/fungal infections would help surgeons limit unnecessary testing. This study evaluates the positivity rate and predictive factors of positive fungal and/or acid-fast bacillus (AFB) cultures after primary, conversion, or revision hip and knee arthroplasty. METHOD: Two hundred thirty-eight knee and hip procedures were done between January 2007 and 2022 where intraoperative AFB/fungal cultures were obtained. Procedures included primary total knee arthroplasty, primary total hip arthroplasty, conversion, first of two-stage, second of two-stage, irrigation and débridement polyexchange, and aseptic revision. Positivity rates of intraoperative AFB/fungal cultures were calculated as binomial exact proportions with 95% confidence intervals and are displayed as percentages. Univariable generalized linear mixed models estimated the unadjusted effects of demographics, individual comorbid conditions, and procedural characteristics on the logit of positive AFB/fungal cultures. RESULTS: Two hundred thirty-eight knee and hip procedures recorded an overall positivity rate of 5.8% for intraoperative AFB/fungal cultures. Aseptic revisions showed the lowest rates of positivity at 3.6%, while conversions showed the highest rates of positivity at 14.3%. The positivity rates are highest among patients who are male (9.0%), of Hispanic origin (12.0%), with body mass index <30 (6.4%), and a Charlson Comorbidity Index <5 (6.1%). History of a prior infection in the same surgical joint showed statistically significant influence of odds of culture positivity with an odds ratio of 3.47 ( P -value: 0.039). Other demographic factors that we investigated including age, sex, race, ethnicity, body mass index, and Charlson Comorbidity Index did not show any notable influence on AFB/fungal positivity rates. CONCLUSION: These results suggest utility in obtaining routine intraoperative AFB/fungal cultures, given the relatively high positivity and poor predictive factors.

Total Joint Arthroplasty in Patients With Lymphedema as Compared to a Propensity-Matched Control Cohort.

Background: Lymphedema is rare in arthroplasty patients but has been associated with a higher complication rate. This study sought to determine the outcomes of total joint arthroplasty in patients with lymphedema as compared to a matched control cohort. Methods: Treatment-control propensity matching was implemented on 335 patients following total knee or hip arthroplasty generating 5-patient sets of one patient with presurgery lymphedema (67 total) to 4 patients without presurgery lymphedema (268 total) and matched on age, sex, and surgery year. Body mass index and presence of diabetes were controlled using multivariable generalized estimating equations. Results: In the lymphedema cohort, 1 patient (1.5%) had a deep vein thrombosis within 90 days of their surgery, 36 (53.7%) were discharged to a rehabilitation center, 16 (23.9%) had a readmission, 14 (20.9%) were admitted to the emergency room within 90 days, 6 (9.0%) experienced infection, and 6 (9.0%) had a revision/reoperation. Lymphedema significantly increased emergency room admission within 90 days (odds ratio [OR] 4.56, P = .01) and non-home discharge (OR 4.14, P < .01), affected readmission within 90 days (OR 2.21, P = .09), revision/reoperation (OR 2.82, P = .09), and no effect on deep vein thrombosis within 90 days (OR 0.57, P = .45), postsurgical infection (OR 1.47, P = .45), length of stay (OR 0.00, P = .99), operative time (OR 0.04, P = .38), or estimated blood loss (OR 0.09, P = .47), after adjusting for various factors. Conclusions: Preoperative lymphedema is a significant risk factor for patients who are undergoing total joint arthroplasty. Preoperative and postoperative modalities should be utilized to help control lymphedema and mitigate these increased risks.

Prevention Techniques Have Had Minimal Impact on the Population Rate of Prosthetic Joint Infection for Primary Total Hip and Knee Arthroplasty: A National Database Study.

BACKGROUND: Several studies over the years have offered modalities that may greatly decrease the rate of periprosthetic joint infection when implemented. As a result, one would expect a drastic decrease in infection rate among the implementing population with its widespread use. The purpose of this study was to assess whether there exists a decrease in infection rate over time, after accounting for available confounding variables, within a large national database. METHODS: A large national database from 2005 to 2019 was queried for primary total hip arthroplasty (THA) and total knee arthroplasty (TKA). In total, 221,416 THAs and 354,049 TKAs were performed over the study period. Differences in 30-day infection rate were assessed with time and available preoperative risk factors using multinominal logistic regressions. RESULTS: Rate of infection overall trended downward for both THA and TKA. After accounting for confounding variables, odds of THA infection marginally decreased over time (odds ratio 0.968 [0.952-0.985], P < .0001), while the odds of a TKA infection marginally increased with time (odds ratio 1.037 [1.020-1.054], P < .0001). CONCLUSION: Individual peer-reviewed publications have presented infection control modalities demonstrating dramatic decreases in infection rate while analysis at a population level shows almost no changes in infection rate over a 15-year time period. This study supports continued investigation for influential modalities in preventing periprosthetic joint infection and care in patient selection for primary hip and knee arthroplasty.

Artificial Intelligence Autonomously Measures Cup Orientation, Corrects for Pelvis Orientation, and Identifies Retroversion From Antero-Posterior Pelvis Radiographs.

BACKGROUND: Measuring cup orientation is time consuming and inaccurate, but orientation influences the risk of impingement and dislocation following total hip arthroplasty (THA). This study designed an artificial intelligence (AI) program to autonomously determine cup orientation, correct for pelvis orientation, and identify cup retroversion from an antero-posterior pelvic radiographs. METHODS: There were 2,945 patients between 2012 and 2019 identified to have 504 computed tomographic (CT) scans of their THA. A 3-dimensional (3D) reconstruction was performed on all CTs, where cup orientation was measured relative to the anterior pelvic plane. Patients were randomly allocated to training (4,000 x-rays), validation (511 x-rays), and testing (690 x-rays) groups. Data augmentation was applied to the training set (n = 4,000,000) to increase model robustness. Statistical analyses were performed only on the test group in their accuracy with CT measurements. RESULTS: AI predictions averaged 0.22 ± 0.03 seconds to run on a given radiograph. Pearson correlation coefficient was 0.976 and 0.984 for AI measurements with CT, while hand measurements were 0.650 and 0.687 for anteversion and inclination, respectively. The AI measurements more closely represented CT scans when compared to hand measurements (P < .001). Measurements averaged 0.04 ± 2.21°, 0.14 ± 1.66°, -0.31 ± 8.35°, and 6.48° ± 7.43° from CT measurements for AI anteversion, AI inclination, hand anteversion, and hand inclination, respectively. AI predictions identified 17 radiographs as retroverted with 100.0% accuracy (total retroverted, n = 45). CONCLUSION: The AI algorithms may correct for pelvis orientation when measuring cup orientation on radiographs, outperform hand measurements, and may be implemented in a timely fashion. This is the first method to identify a retroverted cup from a single AP radiograph.

Predictors of Success With Chronic Antibiotic Suppression for Prosthetic Joint Infections.

BACKGROUND: Management of recurrent prosthetic joint infection (PJI) after attempted surgical eradication remains a challenge. Chronic antibiotic suppression (CAS) is regarded as a reasonable treatment option for select patients with persistent infection or multiple comorbidities. The study seeks to compare cohorts who succeed and fail with CAS. METHODS: This retrospective cohort study assesses patients who were treated with CAS for a PJI. Patients were included if they had a culture-proven PJI and received chronic suppressive antibiotics. Failure of suppression was defined as reoperation after initiating CAS or death occurring as result of infection. A Cox proportional hazards multivariate regression model was used to estimate risk of reoperation as a function of risk factors related to patient comorbidities, surgical history, affected joint, and infecting organism. RESULTS: We identified 45 PJIs (31 knees, 14 hips) managed with CAS with a median follow-up of 50 (95% confidence interval [CI] 33.61-74.02) months. The overall success rate of managing PJI with CAS was 67% (30/45). Controlling for body mass index and Gram status of the organism, total hip arthroplasty patients were less likely than total knee arthroplasty patients to require reoperation (hazard ratio 0.18, 95% CI 0.01-0.96, P = .04). Patients with Gram-positive infections were less likely than those with a Gram-negative infections to require reoperation (hazard ratio 0.22, 95% CI 0.05-0.88, P = .03). Severe antibiotic side effects were rare. Patients who experienced multiple changes to their antibiotic regimen were more likely to fail with CAS. CONCLUSION: CAS is a reasonable strategy in patients with PJI who lack or refuse further surgical treatment options. Most hips and Gram-positive infections treated with CAS successfully avoided reoperation in this cohort.

New Primary Total Knee Arthroplasty Components Versus Other Contemporary Types of Spacers for the Treatment of Chronic Periprosthetic Knee Infection With a Two-Stage Protocol.

The optimal type of antibiotic spacer for the treatment of a knee periprosthetic joint infection (PJI) remains a topic of debate. Although the ultimate goal of an antibiotic spacer is infection control, contemporary spacer iterations, such as the use of a new femoral component (NFC), may offer unique advantages. The primary goal of this study was to compare rates of infection control and functional outcomes between contemporary spacer types. We retrospectively reviewed 96 patients who underwent removal of a total knee arthroplasty with insertion of an antibiotic spacer for knee PJI over a 14-year period at a single institution with a minimum 1-year follow-up. Three patient cohorts were defined based on spacer type: NFC (n=30), cement-on-cement (n=19), and static (n=47). There was no association between spacer type and the odds of infection clearance (P=.60). The NFC spacers resulted in increased knee range of motion before replantation and improved ambulatory status at 8 weeks postre-plantation, although no difference was seen at final follow-up. The use of NFC spacers may provide functional advantages over their contemporary counterparts, and the potential of NFC spacers to be used in single-stage exchange arthroplasty remains an appealing area of investigation. Future high-powered, prospective, noninferiority studies between contemporary spacer types are needed. [Orthopedics. 2022;45(2):109-115.].

Nonoperative Treatment of a Fractured Uncemented Extensively Coated Femoral Stem: A Case Report with 2-Year Follow-up.

CASE: A 62-year-old man who underwent total hip arthroplasty (THA) 17 years earlier presented with a fractured uncemented extensively coated diaphyseal engaging femoral stem. Treatment options, including revision surgery, were discussed, and the patient elected for nonoperative treatment. At 2 years of follow-up, the patient is asymptomatic, radiographs are stable, and he lives an active lifestyle without restrictions. CONCLUSION: Fractures of well-fixed femoral prostheses are rare complications of THA and almost universally require revision surgery. Nonoperative treatment without activity restrictions may be a viable treatment option in select patients to preserve function and maintain quality of life.

Demographic data is more predictive of component size than digital radiographic templating in total knee arthroplasty.

BACKGROUND: Preoperative radiographic templating for total knee arthroplasty (TKA) has been shown to be inaccurate. Patient demographic data, such as gender, height, weight, age, and race, may be more predictive of implanted component size in TKA. MATERIALS AND METHODS: A multivariate linear regression model was designed to predict implanted femoral and tibial component size using demographic data along a consecutive series of 201 patients undergoing index TKA. Traditional, two-dimensional, radiographic templating was compared to demographic-based regression predictions on a prospective 181 consecutive patients undergoing index TKA in their ability to accurately predict intraoperative implanted sizes. Surgeons were blinded of any predictions. RESULTS: Patient gender, height, weight, age, and ethnicity/race were predictive of implanted TKA component size. The regression model more accurately predicted implanted component size compared to radiographically templated sizes for both the femoral (P = 0.04) and tibial (P < 0.01) components. The regression model exactly predicted femoral and tibial component sizes in 43.7 and 43.7% of cases, was within one size 90.1 and 95.6% of the time, and was within two sizes in every case. Radiographic templating exactly predicted 35.4 and 36.5% of cases, was within one size 86.2 and 85.1% of the time, and varied up to four sizes for both the femoral and tibial components. The regression model averaged within 0.66 and 0.61 sizes, versus 0.81 and 0.81 sizes for radiographic templating for femoral and tibial components. CONCLUSIONS: A demographic-based regression model was created based on patient-specific demographic data to predict femoral and tibial TKA component sizes. In a prospective patient series, the regression model more accurately and precisely predicted implanted component sizes compared to radiographic templating. LEVEL OF EVIDENCE: Prospective cohort, level II.

Minimum twelve-year follow-up of fixed- vs mobile-bearing total knee arthroplasty: Double blinded randomized trial.

BACKGROUND: Total knee arthroplasty (TKA) with fixed-bearing (FB) implants have demonstrated impressive functional results and survival rates. Meanwhile, rotating-platform (RP) constructs have biomechanically shown to reduce polyethylene wear, lower the risk of component loosening, and better replicate anatomic knee motion. There is growing question of the clinical impact these design changes have long-term.Questions/purposes: The aim of this double-blinded prospective randomized trial was to compare function and implant survival in patients who received either FB or RP press-fit condylar Sigma (PFC Sigma, DePuy, Warsaw, IN) total knee replacements at a minimum follow-up of twelve years. PATIENTS AND METHODS: Patient reported outcome measures used included the functional Knee Society Score, Western Ontario and McMaster University Osteoarthritis Index (WOMAC) scores, Medical Outcomes Short Form-36 (SF-36) score, and satisfaction assessment on a four-point Likert scale. The data was collected from times preoperative, two-years, and final encounter (mean 13.95 years). A total of 28 RP and 19 FB knees (58.8%) were analyzed at the final follow-up. RESULTS: Among all patients, KSS and WOMAC scores statistically improved from pre-op to 2-year, while KSS statistically worsened from 2-year to final follow-up. The RP group averaged better follow-up scores in all assessments at the final follow-up with exception of overall satisfaction. There was no statistically significant difference in the functional Knee Society Score, Short Form-36, WOMAC scores, patient satisfaction or implant survival between the two groups at any measured period. CONCLUSIONS: The use of a fixed-bearing or rotating-platform design does not convey significant superiority in terms of function or implant longevity at a minimum twelve years after total knee arthroplasty. LEVEL OF EVIDENCE: Level I, Experimental study, randomized controlled trial (RCT).

A precise method for determining acetabular component anteversion after total hip arthroplasty.

AIMS: Several radiological methods of measuring anteversion of the acetabular component after total hip arthroplasty (THA) have been described. These are limited by low reproducibility, are less accurate than CT 3D reconstruction, and are cumbersome to use. These methods also partly rely on the identification of obscured radiological borders of the component. We propose two novel methods, the Area and Orthogonal methods, which have been designed to maximize use of readily identifiable points while maintaining the same trigonometric principles. PATIENTS AND METHODS: A retrospective study of plain radiographs was conducted on 160 hips of 141 patients who had undergone primary THA. We compared the reliability and accuracy of the Area and Orthogonal methods with two of the current leading methods: those of Widmer and Lewinnek, respectively. RESULTS: The 160 anteroposterior pelvis films revealed that the proposed Area method was statistically different from those described by Widmer and Lewinnek (p < 0.001 and p = 0.004, respectively). They gave the highest inter- and intraobserver reliability (0.992 and 0.998, respectively), and took less time (27.50 seconds (sd 3.19); p < 0.001) to complete. In addition, 21 available CT 3D reconstructions revealed the Area method achieved the highest Pearson's correlation coefficient (r = 0.956; p < 0.001) and least statistical difference (p = 0.704) from CT with a mean within 1° of CT-3D reconstruction between ranges of 1° to 30° of measured radiological anteversion. CONCLUSION: Our results support the proposed Area method to be the most reliable, accurate, and speedy. They did not support any statistical superiority of the proposed Orthogonal method to that of the Widmer or Lewinnek method. Cite this article: Bone Joint J 2019;101-B:1042-1049.

Cognitive Skills Assessment for the Aging Orthopaedic Surgeon: AOA Critical Issues.

Physician leaders are increasingly confronted with the challenge of evaluating the performance of surgical colleagues during the last phase of their careers. Identification of physicians with declining cognitive and clinical skills must be balanced against awareness of laws protecting colleagues from discrimination. Responding successfully to this challenge requires appropriate policies, reliable data, standardized evaluation tools, consistent documentation, and the development of compassionate and effective solutions that avoid discriminatory practices. Surgical champions are essential for promoting self-regulation. Performance evaluations should comply with medical staff bylaws and institutional wellness policies.

Total Knee Arthroplasty in Patients with Blount Disease or Blount-Like Deformity.

Blount disease is associated with complex deformity of the proximal tibia, and some patients will develop knee osteoarthritis. Five patients (eight knees) with Blount disease or Blount-like deformity underwent total knee arthroplasty. Mean proximal tibial metaphyseal-diaphyseal angle was 20.75°. Each patient had substantial posteromedial tibial bony defects and six knees required extensive medial releases. Two knees required increased constraint at index procedure. One patient has undergone bilateral revision surgery with rotating hinge prostheses. Mean WOMAC scores were 13.5 and Knee Society scores were 212.5 at average 75.2 month follow-up. Despite technical challenges, patients with these deformities can have successful outcomes after total knee arthroplasty. Surgeons should be prepared to address posteromedial tibial bony defects and consider constrained arthroplasty at the index procedure.

Hip Arthroplasty or Medical Management: A Challenging Treatment Decision for Younger Patients.

The two main treatment options for total hip arthroplasty (THA), medical management and surgical intervention, have advantages and disadvantages, creating a challenging decision. Treatment decisions are further complicated in a younger population (≤50) as the potential need for revision surgery is probable. We examined the relationship of selected variables to the decision-making process for younger patients with symptomatic OA. Thirty-five participants chose surgical intervention and 36 selected medical management for their current treatment. Pain, activity restrictions, and total WOMAC scores were statistically significant (P < .05) for patients selecting surgical intervention. No difference in quality of life was shown between groups. Pain was the only predictor variable identified, however, activity restrictions were also influential variables as these were highly correlated with pain.

The relationship between knee arthroplasty and foot loading.

Surgeons have questioned whether foot deformity applies abnormal loading on a knee implant. A total of 24 patients with mild knee deformity underwent a static recording of foot loading prior to and at 3 months following knee replacement. Of these patients, 13 had a preoperative varus deformity. The recorded postoperative to preoperative loading in all 6 geographic sites was decreased by an average of 10%. The largest changes were observed in the hallux and lesser toe masks, whereas the postoperative to preoperative foot pressure ratio in the metatarsal head (lateral and medial), heel, and midfoot masks was 0.94. This preliminary investigation reveals a minimal change in geographic foot loading following total knee arthroplasty in patients with mild knee deformity.

Assessment of HIT antibody complex in hip fracture patients receiving enoxaparin or unfractionated heparin.

Thromboembolic disease is a common complication of hip fracture in the elderly. Anticoagulants represent a standard of care in preventing postoperative thrombotic complications following surgical fixation. We asked whether levels of antibody to heparin-platelet factor 4 (PF4) complex were differentially present in unfractionated heparin (UFH) versus Enoxaparin, following hip fracture and whether one particular subtype of antibodies was more prevalent. Plasma samples from elderly patients sustaining a hip fracture treated with either enoxaparin or UFH were collected pre- and postoperatively and analyzed using enzyme-linked immunosorbent assay (ELISA) sandwich method for the prevalence of antiheparin-PF4 antibodies and later subtyped. The prevalence of antiheparin-PF4 antibodies was higher in the UFH group especially on postoperative day 7. Patients treated with UFH showed a greater prevalence of antiheparin-PF4 antibodies and a greater prevalence of immunoglobulin G (IgG) subtype. Heparin and enoxaparin are capable of generating heparin-induced thrombocytopenia (HIT) antibodies in elderly patients undergoing orthopedic surgery but perhaps not to the same extent. When comparing low-molecular-weight heparin (LMWH) with UFH, the incidence of new antiheparin-PF4 antibody production is higher in patients treated with UFH.

Fixed- vs mobile-bearing total knee arthroplasty: does it make a difference?--a prospective randomized study.

The purpose of this prospective, randomized study was to compare the early clinical and functional results of primary total knee arthroplasty using a fixed-bearing (FB) and a rotating-platform (RP) prosthesis. Outcomes including range of motion (ROM), Knee Society Score, Western Ontario MacMaster (WOMAC), and Short Form-36 (SF-36) were measured preoperatively and at 6 weeks, 3 months, 6 months, 1 year, and 2 years. Radiographic analysis was performed. There were 72 FB and 68 RP knees. The RP group had a greater ROM at 6 weeks and 1 year. This difference was not statistically significant at 2 years. There were no differences in the ROM at any other period. There were no significant differences in Knee Society Score, Short Form-36, or Western Ontario MacMaster scores at any period. No clinically significant differences were noted in the radiographic analysis. The use of a FB or RP design did not affect the early functional outcomes after total knee arthroplasty.