Incidence of patella baja and pseudopatella baja in aseptic revision total knee arthroplasty.

INTRODUCTION: There are two variants regarding the low location of the patella in relation to the tibio-femoral joint line: patella baja (PB) and pseudo-patella baja (PPB). The purpose of this study is to investigate the incidence of PB and PPB in a cohort of patients that underwent revision total knee arthroplasty (rTKA) for aseptic reasons and describe any differences in each group's ROM. METHODS: This retrospective study included 114 patients that underwent aseptic revision TKA surgery between 2017 and 2022. Patients were revised either for stiffness (Group 1) or aseptic loosening/instability (Group 2). The Insall-Salvati ratio (ISR) and Blackburne-Peel ratio (BPR) were used to evaluate the patellar position. ISR < 0.8 defined PB, while cases with ISR ≥ 0.8 and BPI < 0.54 were defined as PPB. ROM was measured and a subanalysis was conducted to investigate the progression of the values of ISR and BPR. RESULTS: 55 patients comprised Group 1, and 59 patients comprised Group 2. Overall, 13 cases (11.4%) had PB before rTKA and 24 (21%) had PB after rTKA. Cases with PPB were 13 (11.4%) before and 34 (29.9%) after rTKA. Group 1 patients presented with more PB before and after rTKA (12.8% vs 10.2% and 27.3% vs 15.2% respectively). However, after rTKA Group 1 patients presented with less PPB (20%) compared to Group 2 (39%) (p = 0.02). In Group 1, patients with PPB after rTKA had less ROM compared to those without PPB [83.2 (± 21.9) vs 102.1 (± 19.9) (p = 0.025)]. The subanalysis (69 patients) showed a statistically significant decrease in ISR before and after rTKA (p = 0.041), and from the native knee to post-rTKA (p = 0.001). There was a statistically significant decrease in BPR before and after rTKA (p = 0.001) and from the native knee to both pre- and post-rTKA (p < 001). CONCLUSION: After undergoing rTKA, the incidences of both patella baja (PB) and pseudo-patella baja (PPB) increased. Stiffness in the knee was associated with a higher incidence of PB, while non-stiffness cases showed a significantly higher incidence of PPB. Patients with stiff knees and PPB after rTKA experienced a significant reduction in range of motion (ROM). Additionally, the study revealed a noteworthy decrease in ISR and BPR with each subsequent surgery. This information is crucial for healthcare providers, as it sheds light on potential risks and outcomes of rTKA, allowing for improved patient management and surgical decision-making. LEVEL OF EVIDENCE: III.

Taking a Deeper Dive Into Malnutrition and Revision Arthroplasty: When Do Nutritionists Get Involved?

BACKGROUND: Perioperative malnutrition is associated with increased complications and mortality following revision total joint arthroplasty (rTJA). Nutritional consultations are useful in characterizing patient nutritional status but are inconsistently utilized post rTJA. We sought: 1) to describe the prevalence of nutritional consultations post rTJA, 2) to determine if septic rTJA patients needed consultations more often, and 3) if a diagnosis of 'malnutrition' from the nutritionist conferred increased readmission rates. METHODS: A retrospective study of 2,697 rTJAs performed in a single institution over a 4-year period was performed. Patient demographics, reasons for rTJA, occurrences of nutritional consultation (indicated if body mass index < 20, malnutrition screening tool score ≥ 2, or poor oral intake postoperatively), specific nutritional diagnosis (according to 2020 Electronic Nutrition Care Process Terminology and 90-day readmission rates were recorded and analyzed). Rates of consultations and adjusted logistic regressions were calculated. RESULTS: There were 501 patients (18.6%) who required nutritional consultations, with 55 (11.0%) of these patients receiving a 'malnutrition' diagnosis. Septic rTJA patients required significantly more nutritional consultations (P < .01) and were significantly more likely to have 'malnutrition' (P = .49). A diagnosis of malnutrition was associated with the highest odds of all-cause readmission (odds ratio (OR) = 3.89, P = .01), which was even higher than undergoing a septic rTJA. CONCLUSION: Nutritional consultations occur frequently following rTJA. Patients who receive a diagnosis of 'malnutrition' through consultation are at significantly higher risk for readmission and require close follow-up. Future efforts are needed to further characterize these patients in order to identify as well as optimize them preoperatively.

Does Acetabular Bone Loss Severity Associate With Patient-Reported Outcome Measures and Reoperation Rate in Revision Total Hip Arthroplasty?

BACKGROUND: Acetabular bone loss is a challenging clinical problem when performing revision total hip arthroplasty (rTHA). This study aimed to evaluate how acetabular bone loss severity influences (1) clinical outcomes and (2) patient-reported outcome measures (PROMs) in rTHA patients. METHODS: Patients who underwent rTHA with acetabular component revision from January 2016 to February 2022 were included. Treating surgeons determined Paprosky acetabular bone loss classification intraoperatively. Patients were grouped based on numeric classification (PI, PII, or PIII) to categorize severity. Hip disability and Osteoarthritis Outcome Score for Joint Replacement (HOOS, JR.) and Lower Extremity Activity Scale (LEAS) score were collected preoperatively and 1 year postoperatively. There were 197 patients included. Paprosky classification was PI for 47 patients (23.9%), PII for 113 patients (57.4%), and PIII for 37 patients (18.8%). Mean clinical follow-up was 29 months (range, 1 to 69). RESULTS: Reoperation rate was 0% (0 patients), 6.2% (7 patients), and 10.8% (4 patients) for PI, PII and PIII groups respectively (P = .052). Mean preoperative HOOS, JR. and LEAS for PI, PII and PIII groups were significantly different, but 1-year postoperative HOOS, JR. and LEAS did not differ significantly. Rates of HOOS, JR. minimal clinically important difference achievement differed significantly between bone loss groups. CONCLUSION: In this study of rTHA patients, greater acetabular bone loss severity was associated with worse preoperative PROMs and trended toward higher reoperation rate. Postoperative PROMs for bone loss severity groups were statistically similar. Patients who had worse acetabular bone loss were more likely to achieve HOOS, JR. minimal clinically important difference postoperatively. LEVEL OF EVIDENCE: III.

Which Combination is the Best? A Comparison of the Predictive Potential of Serum Biomarker Combinations to Diagnose Periprosthetic Joint Infection.

BACKGROUND: Without a gold-standard test, recent periprosthetic joint infections (PJI) literature has explored the utility of combining serological results, with promising findings. However, previous studies evaluated fewer than 200 patients and often studied only 1 to 2 test combinations. The purpose of this study was to accumulate a large single-institution cohort of revision total joint arthroplasty (rTJA) patients to determine the diagnostic utility of combination serum biomarkers to identify PJI. METHODS: A single institution longitudinal database was assessed to identify all patients who underwent rTJA from 2017 to 2020. There were 1,363 rTJA patients (715 rTKA patients and 648 rTHA patients) including 273 PJI cases (20%) analyzed. The PJI was diagnosed post-rTJA utilizing 2011 Musculoskeletal Infection Society (MSIS) criteria. Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), D-dimer, and interleukin 6 (IL-6) were systematically collected for all patients. RESULTS: The rTKA combination markers of CRP + ESR (sensitivity: 78.3%, specificity: 88.8%, positive predictive value (PPV): 70.0%, negative predictive value (NPV): 92.5%), CRP + D-dimer (sensitivity: 60.5%, specificity: 92.6%, PPV: 63.4%, NPV: 91.7%), and CRP + IL-6 (sensitivity: 38.5%, specificity: 100.0%, PPV: 100.0%, NPV: 92.9%) all yielded higher specificity than CRP alone (sensitivity: 94.4%, specificity: 75.0%, PPV: 55.5%, NPV: 97.6%). Similarly, the rTHA combination markers of CRP + ESR (sensitivity: 70.1%, specificity: 88.8%, PPV: 58.1%, NPV: 93.1%), CRP + D-dimer (sensitivity: 57.1%, specificity: 90.1%, PPV: 43.2%, NPV: 94.1%), and CRP + IL-6 (sensitivity: 21.4%, specificity: 98.4%, PPV: 60.0%, NPV: 91.7%) all yielded higher specificity than CRP alone (sensitivity: 84.7%, specificity: 77.5%, PPV: 45.4%, NPV: 95.8%). CONCLUSION: Overall, in diagnosing PJI for both rTKA and rTHA, 2-marker combinations yielded higher specificity, while 3-marker combinations yielded higher sensitivity compared to CRP alone. However, compared to all 2-marker and 3-marker combinations, CRP demonstrated superior overall diagnostic utility. These findings suggest that routine combination testing of markers for PJI diagnosis may be excessive and an unnecessary use of resources, especially in resource-limited situations.

Monobloc Dual Mobility With a Minimum 5-Year Follow-Up: A Safe and Effective Solution in Primary Total Hip Arthroplasty.

BACKGROUND: Instability constitutes over 20% of revisions after total hip arthroplasty (THA). Dual mobility (DM) designs were introduced as a solution to this problem. However, the few publications that have reported promising results for monobloc DM constructs have been limited by sample size or length of follow-up. The purpose of this study is to evaluate mid-term outcomes (minimum 5-year follow-up) of a single-surgeon series utilizing a monobloc DM acetabular component in patients with high risk for dislocation. METHODS: This is a single-surgeon consecutive series of 207 primary THAs implanted with a monobloc DM component in patients who were considered at high risk for dislocation. Patient demographics and case-specific data were collected retrospectively. All patients had a minimum of 5-year follow-up. The Mann-Whitney U test was used to assess continuous variables, whereas categorical variables were analyzed using the chi-square test. Survival probability was calculated using the Kaplan-Meier method. RESULTS: Radiographic analysis did not reveal acetabular radiolucency in any patients, and there were no revisions for aseptic loosening. In addition, there were no dislocations. Seven of 205 patients (3.4%) were revised, 5 on the femoral side due to periprosthetic fracture and the remaining two for infection. Survivorship of the acetabular component from revision was 99%. The mean Veteran RAND (VR-12) physical score improved from 7 (standard deviation [SD]: 13.7) preoperatively to 9.5 (SD: 17.6) at the final follow-up. Similarly, the hip disability osteoarthritis score improved from 8 (SD: 17.9) preoperatively to 21.2 (SD: 37). CONCLUSION: Monobloc DM components reliably prevent dislocation after primary THA in high-risk patients. At mid-term follow-up, this DM monobloc component demonstrates excellent implant survivorship, radiographic fixation, and improved functional outcomes.

Heterotopic Ossification Negatively Influences Range of Motion After Revision Total Knee Arthroplasty.

BACKGROUND: The incidence of heterotopic ossification (HO) after total knee arthroplasty (TKA) varies and is of unclear clinical significance. This study aimed to identify the incidence of HO in patients undergoing revision TKA for either stiffness or aseptic loosening/instability and determine if the presence of HO is associated with inferior absolute range of motion (ROM) and ROM gains. METHODS: Eighty-seven patients were prospectively enrolled and separated into 2 cohorts to evaluate ROM after revision TKA (2017-2019). Group 1 (N = 40) patients were revised for stiffness, while group 2 (N = 47) patients were revised for either aseptic loosening or instability. Goniometer-measured ROM values were obtained preoperatively and at 6 weeks, 6 months, and 1 year postoperatively. Statistical analysis included a Fisher's exact test to assess for an association between preoperative HO and final ROM at 1 year after revision TKA. RESULTS: HO was identified on preoperative radiographs in 17 patients (20%). There was a significantly higher rate of preoperative HO in patients revised for stiffness compared to patients revised for instability or loosening (30% vs 11%; P = .03). Five cases of HO qualitatively identified as most clinically severe were associated with lower ROM at each time point compared to the remainder of HO cases in this study cohort (P < .02). CONCLUSION: The presence of HO is greater in patients undergoing revision TKA for stiffness. Additionally, HO severity appears to have a major effect on preoperative and postoperative ROM trajectory. This information should help guide patient expectations and highlight the need for a comprehensive, standardized classification system for HO.

Irrigation and Debridement With Implant Retention: Does Chronicity of Symptoms Matter?

BACKGROUND: Periprosthetic joint infection (PJI) remains a rare, yet devastating complication of total joint arthroplasty (TJA). Chronic infection is generally considered a contraindication to debridement, antibiotics, and implant retention (DAIR); however, outcomes stratified by chronicity have not been well documented. METHODS: A retrospective review of all DAIR cases performed at a single institution from 2008 to 2015 was performed. Chronicity of PJI was categorized as acute postoperative, chronic, or acute hematogenous. Failure after DAIR, defined as re-revision for infection recurrence with the same organism, was evaluated between the 3 chronicity groups at 90 days as well as at a minimum 2-year follow-up. RESULTS: Overall, 248 patients undergoing DAIR for total hip arthroplasty or total knee arthroplasty PJI were included. Categorization of PJI was acute (acute postoperative) in 59 cases (24%), chronic in 54 (22%), and acute hematogenous in 135 (54%). DAIR survivorship was 47% (range 0.3-10 years). Overall, there were 118 (47.6%) treatment failures after DAIR with a minimum of 2-year follow-up. There was no difference in failure rate between total hip or total knee arthroplasty patients (P = .07). Patients infected with Staphylococcus conferred a higher risk of failure for all DAIR procedures regardless of chronicity category. CONCLUSION: Identification of microbial species prior to undertaking DAIR may be more clinically relevant than stratification according to chronicity category when considering treatment options.

The Influence of Spacer Design on the Rate of Complications in Two-Stage Revision Hip Arthroplasty.

BACKGROUND: Antibiotic cement spacers are used during 2-stage revision total hip arthroplasty for prosthetic joint infection. Complications including dislocation and periprosthetic fracture have been reported but a large cohort comparing spacer design features is lacking. We aimed to determine if spacer design is associated with perioperative complications. METHODS: We performed a retrospective review of antibiotic cement spacers implanted between 2004 and 2014. Radiographic assessment included leg length, offset, and bone loss (Paprosky classification). Clinical outcomes included dislocation, periprosthetic fracture, spacer fracture, infection cure, and overall reoperation rate. Univariate analysis, Student's t-test, chi-squared test, or Kruskal-Wallis test was employed (P < .05). RESULTS: One hundred eighty-five patients were treated: 42% were female and mean age was 64 years (range 24-93, standard deviation 13.6). Spacer types were (1) molded (53%), (2) antibiotic-coated prosthesis (30%), (3) handmade (12%); and (4) prefabricated (4%). Cemented acetabular liners were used in 3% (6/185). There was no loss to follow-up during the interstage period. Spacer complications occurred in 26% (48/185). Dislocation occurred in 9% (17/185) and was associated with reduced femoral offset of >5 mm (P = .033) and increased bone loss (P = .01). Spacer fracture occurred in 8% (14/185); 12% (12/97) molded versus 8% (2/23) handmade (P = .02). Periprosthetic femur fracture was associated with increased offset >5 mm (P = .01) and extended trochanteric osteotomy (P = .001). CONCLUSION: During 2-stage total hip arthroplasty, antibiotic-loaded cement spacers had an overall complication rate of 26%. Spacer design, acetabular and femoral bone loss, and offset restoration were significantly associated with perioperative complications. We recommend the optimization of antibiotic-loaded cement spacer placement to minimize potential complications by focusing on restoration of leg-length and offset, ensuring adequate femoral fixation and paying attention to selection of an appropriate head/neck ratio.

Preoperative Malnutrition Negatively Correlates With Postoperative Wound Complications and Infection After Total Joint Arthroplasty: A Systematic Review and Meta-Analysis.

BACKGROUND: Malnutrition continues to be prevalent in the general population. A variety of studies have correlated poor nutritional status with reduced perioperative outcomes. However, the correlation between serologic malnutrition and arthroplasty outcomes has not been systematically evaluated. The purpose of this study was to determine if serologic malnutrition has a correlation with postoperative wound infection, as well as other complications, after total joint arthroplasty. METHODS: A systematic review of the literature was performed to identify studies that reported on outcomes for patients who were malnourished and had undergone a total hip or knee arthroplasty. RESULTS: Twenty studies were included for review. Based on the quality of the evidence of the different studies, the balance between desirable/undesirable outcomes and the values of patients, there was a strong recommendation that preoperative serologic markers of malnutrition are significantly associated with inferior postoperative outcomes. All 20 studies analyzed albumin as a marker for malnutrition. Eleven (55%) studies used the total lymphocyte count, and 6 (30%) studies reported transferrin as a marker for malnutrition. Among 20 studies, 18 (90%) studies reported a correlation with at least one serological marker and poor postoperative outcomes. Finally, patients with an albumin level <3.5 dg/L were more likely to develop a postoperative wound complication (odds ratio: 2.176; 95% confidence interval: 1.916-2.471). CONCLUSIONS: There is strong evidence that serologic malnutrition was associated with increased risk of poor postoperative outcome across all total joint replacement interventions.

Increased Staphylococcus aureus Nasal Carriage Rates in Rheumatoid Arthritis Patients on Biologic Therapy.

BACKGROUND: Rheumatoid arthritis patients are at increased risk for periprosthetic joint infection after arthroplasty. The reason is multifactorial. Nasal colonization with Staphylococcus aureus is a modifiable risk factor; carriage rates in RA patients are unknown. The goal of this study is to determine the S aureus nasal carriage rates of RA patients on biologics, RA patients on traditional disease-modifying anti-rheumatic drugs (DMARDs), and osteoarthritis. METHODS: Consecutive patients with RA on biologics (±DMARDs), RA on non-biologic DMARDs, or OA were prospectively enrolled from April 2017 to May 2018. One hundred twenty-three patients were determined necessary per group to show a difference in carriage rates. Patients underwent a nasal swab and answered questions to identify additional risk factors. S aureus positive swabs were further categorized using spa typing. Logistic regression evaluated the association with S aureus colonization between the groups after controlling for known risk factors. RESULTS: RA patients on biologics, 70% of whom were on DMARDs, had statistically significant increase in S aureus colonization (37%) compared to RA on DMARDs alone (24%), or OA (20%) (P = .01 overall). After controlling for glucocorticoids, antibiotic use, recent hospitalization, and diabetes, RA on biologics had a significant increased risk of S aureus nasal colonization (Odds ratio 1.80, 95% confidence interval 1.00-3.22, P = .047). CONCLUSION: S aureus colonization risk was increased for RA on biologics compared to RA not on biologics and OA. Nasal S aureus carriage increases the risk of surgical site infection; this modifiable risk factor should be addressed prior to total joint arthroplasty for this higher risk patient group.

Proximal femoral replacement in non-oncologic patients undergoing revision total hip arthroplasty.

PURPOSE: Proximal femoral replacements (PFRs) have been recently utilized in complex revision arthroplasties where proximal femoral bone is compromised. The purpose of this study is to evaluate the clinical outcomes, complications, and survivorship of PFRs as a salvage treatment for severe bone loss after non-oncologic revision total hip arthroplasty. METHODS: This is a retrospective review of all patients who underwent femoral revision surgery using a single design PFR between 2004 and 2013 at our institution. Forty patients (41 hips) were included with a mean age of 64 years (29-90). According to Paprosky classification, 15 femurs had type IIIB defect, and 26 had type IV defect. Patients were followed for a mean of five years (2-10). The average length of reconstruction was 150 mm (81-261). A Kaplan-Meier analysis was used to determine the survival of the PFR. RESULTS: A total of nine patients (9 PFRs, 22%) were re-operated upon. Three re-operations were for infection, two for dislocation, two for aseptic loosening, and two for periprosthetic fracture. The survivorship at five years was 95.1% for revision of the femoral stem for aseptic loosening. We did not find length of the segmental reconstruction or the indication for revision, to be a risk factor for implant failure or re-revision. CONCLUSIONS: Proximal femoral replacements have shown an acceptable survivorship in non-oncologic revision hip arthroplasties for severe proximal femoral bone loss. The frequent use of constrained liners may decrease the risk of dislocation due to the loss of the abductor mechanism encountered in these complex reconstructions.

Changes in Markers of Thrombin Generation and Interleukin-6 During Unicondylar Knee and Total Knee Arthroplasty.

BACKGROUND: Total knee arthroplasty (TKA) is associated with a risk of thromboembolism requiring routine thromboprophylaxis, but there is debate about the risk with unicondylar knee arthroplasty (UKA) as it is a more minor procedure. We sought to investigate the relative risk of thromboembolism with UKA compared to TKA and one-staged bilateral TKA (BTKA) by measuring the increase in circulating biochemical markers of thrombin generation during the procedures. Degree of surgical trauma was also assessed by measuring interleukin-6, a marker of metabolic injury. METHODS: We prospectively studied a total of 75 patients: 25 patients undergoing UKA, unilateral TKA, and BTKA, respectively. All patients had surgery performed with tourniquet and received no tranexamic acid. Blood samples were taken during surgery and assayed for circulating markers of thrombin generation: prothrombin fragment 1+2 (F1+2) and thrombin-antithrombin complexes plus interleukin-6. RESULTS: Thrombin-antithrombin complexes, increased during all time points (P < .001) but was not significantly different between surgical treatment groups. F1+2 also rose significantly during surgery, with no significant difference between UKA and TKA. There was, however, a significant difference in F1+2 between BTKA and UKA or TKA (P < .02). Interleukin-6 rose minimally with UKA but rose significantly with TKA and BTKA (P < .001). CONCLUSION: Based on these data of circulating biochemical markers, patients undergoing UKA are at similar risk of thromboembolism with respect to TKA despite a lower index of metabolic injury. We believe that UKA patients should receive thromboprophylaxis comparable to TKA patients.

The Influence of a Failed Irrigation and Debridement on the Outcomes of a Subsequent 2-Stage Revision Knee Arthroplasty.

BACKGROUND: Previous work has suggested a failed irrigation and debridement (I&D) before a 2-stage exchange negatively impacts the outcome of the subsequent 2-stage revision. METHODS: This was a retrospective review of 132 patients who underwent a 2-stage exchange without prior I&D (2-Stage), and 45 patients had a failed I&D before their 2-stage exchange (I&D+2Stage) between April 2009 and April 2015. Charts were reviewed for patient demographics, presenting inflammatory laboratory values, type of antibiotic spacer used, surgical details, microbiology data, length of postoperative antibiotic treatment, and reoperation. A logistic regression was used to assess the association between I&D and reoperation. RESULTS: The I&D+2Stage group had an 82.2% success rate, and the 2-Stage group had an 82.5% success rate (P = .95). The odds of reoperation for infection with the use of greater than 2 grams of vancomycin was 0.33 (P = .01, 95% confidence interval 0.14-0.79) as compared with having less than 2 grams of vancomycin in the construct. Spacer type, having a prior I&D to the 2-stage procedure, being infected with an antibiotic resistant organism, total grams of aminoglycoside were not associated with a risk of failure. CONCLUSION: Success rates between the I&D+2Stage group and the 2-Stage group were similar. The use of greater than 2 grams of vancomycin in the spacer construct decreased the odds of reoperation. I&D before a 2-stage exchange may not negatively influence the outcomes of a subsequent 2-stage revision procedure and requires further investigation.

Histopathological characterization of corrosion product associated adverse local tissue reaction in hip implants: a study of 285 cases.

BACKGROUND: Adverse local tissue reaction (ALTR), characterized by a heterogeneous cellular inflammatory infiltrate and the presence of corrosion products in the periprosthetic soft tissues, has been recognized as a mechanism of failure in total hip replacement (THA). Different histological subtypes may have unique needs for longitudinal clinical follow-up and complication rates after revision arthroplasty. The purpose of this study was to describe the histological patterns observed in the periprosthetic tissue of failed THA in three different implant classes due to ALTR and their association with clinical features of implant failure. METHODS: Consecutive patients presenting with ALTR from three major hip implant classes (N = 285 cases) were identified from our prospective Osteolysis Tissue Database and Repository. Clinical characteristics including age, sex, BMI, length of implantation, and serum metal ion levels were recorded. Retrieved synovial tissue morphology was graded using light microscopy. Clinical characteristics and features of synovial tissue analysis were compared between the three implant classes. Histological patterns of ALTR identified from our observations and the literature were used to classify each case. The association between implant class and histological patterns was compared. RESULTS: Our histological analysis demonstrates that ALTR encompasses three main histological patterns: 1) macrophage predominant, 2) mixed lymphocytic and macrophagic with or without features of associated with hypersensitivity/allergy or response to particle toxicity (eosinophils/mast cells and/or lymphocytic germinal centers), and 3) predominant sarcoid-like granulomas. Implant classification was associated with histological pattern of failure, and the macrophagic predominant pattern was more common in implants with metal-on-metal bearing surfaces (MoM HRA and MoM LHTHA groups). Duration of implantation and composition of periprosthetic cellular infiltrates was significantly different amongst the three implant types examined suggesting that histopathological features of ALTR may explain the variability of clinical implant performance in these cases. CONCLUSIONS: ALTR encompasses a diverse range of histological patterns, which are reflective of both the implant configuration independent of manufacturer and clinical features such as duration of implantation. The macrophagic predominant pattern and its mechanism of implant failure represent an important subgroup of ALTR which could become more prominent with increased length of implantation.

Prolonged Length of Stay Is Not an Acceptable Alternative to Coded Complications in Assessing Hospital Quality in Elective Joint Arthroplasty.

We sought to determine if prolonged length of stay (pLOS) is an accurate measure of quality in total hip and knee arthroplasty (THA and TKA). Coded complications and pLOS for 5967 TKA and 4518 THA patients in our hospital discharged between 2009 and 2011 were analyzed. Of 727 patients with pLOS, only 170 also had a complication, yielding a sensitivity of 41.4% (95% CI: 36.7, 46.2) with a positive predictive value (PPV) of just 23.4% (95% CI: 20.3, 26.4). Specificity (94.5% [95% CI: 94.0, 94.9]) and negative predictive value (NPV) (97.5% [95% CI: 97.2, 97.8]) were high, due to the large number of patients without complications or pLOS. This suggests that risk-adjusted pLOS is an inadequate measure of patient safety in primary THA and TKA.

Adaptive immune responses in patients requiring revision after total knee arthroplasty.

Dissatisfaction occurs in nearly 20% of patients after total knee arthroplasty (TKA); however, there remains only limited understanding of the biologic mechanisms that may contribute to suboptimal postoperative outcomes requiring revision surgery. Expansion of effector T and B cells, could promote an abnormal healing response via local or peripheral immune system mechanisms and contribute to inferior outcomes necessitating revision TKA. In this pilot study, we hypothesized that patients suffering from complications of arthrofibrosis or instability may exhibit differences in adaptive immune function. Patients (n = 31) undergoing revision TKA for an indication of arthrofibrosis or instability were prospectively enrolled. Whole blood and synovial fluid (SF) from the operative knee were collected at time of surgery. Peripheral blood mononuclear cells were isolated and analyzed by flow cytometry. Serum and SF were assessed for immunoglobulin levels by Luminex and antiphospholipid antibodies by enzyme-linked immunoassay. No significant differences were observed in peripheral blood T/B cell populations or serum immunoglobulins levels between groups. SF analysis demonstrated significant differences between the two groups, with higher levels of immunoglobulin G1 (IgG1) (p = 0.0184), IgG3 (p = 0.0084) and antiphosphatidyl serine IgG (p = 0.034) in arthrofibrosis relative to instability patients. Increased levels of both IgG subclasses and antiphospholipid antibodies in the SF suggest that intra-articular T-B cell interactions, potentially triggered by exposure to apoptotic components generated during post-op healing, could be functioning as a source of immune complexes that fuel fibrous tissue growth in arthrofibrotic patients.

Clinical and Histological Features of Prosthetic Joint Infections May Differ in Patients With Inflammatory Arthritis and Osteoarthritis.

Background: Patients with inflammatory arthritis are at increased risk of prosthetic joint infections (PJIs), but diagnosis in these patients can be challenging because active inflammatory arthritis produces elevated inflammatory markers that may mimic those seen in PJI. Purpose: In this pilot study, we sought to identify the clinical, microbiologic, and histopathologic features of culture-positive and culture-negative PJI in patients with inflammatory arthritis who underwent total hip arthroplasty (THA) or total knee arthroplasty (TKA). We also sought to obtain preliminary data to support a definitive study of optimal methods for PJI diagnosis in patients with inflammatory arthritis. Methods: We performed a retrospective analysis of TKA and THA patients treated for PJI from 2009 to 2018 at a single tertiary care orthopedic institution. Data were extracted from a longitudinally maintained hospital infection database. We reviewed hematoxylin and eosin slides of osteoarthritis and inflammatory arthritis PJI cases matched 3:1, respectively, by age, sex, and culture status. Clinical characteristics were evaluated using the Fisher exact test, χ2 test, Student t test, and Mann-Whitney U test where appropriate. Results: A total of 807 PJI cases were identified (36 inflammatory arthritis and 771 osteoarthritis cases). Patients with inflammatory arthritis presented younger, had a higher Charlson Comorbidity Index, more frequently used glucocorticoids, were more likely women, and had a higher proportion of culture-negative PJI compared with osteoarthritis patients. Of the 88 inflammatory arthritis cases reviewed for histopathology, a higher proportion of culture-positive than culture-negative PJI cases had >10 polymorphonuclear leucocytes per high-power field and met Musculoskeletal Infection Society criteria but presented with less chronic inflammation. Conclusions: This retrospective prognostic study suggests that culture-negative PJI may be more frequent in patients with inflammatory arthritis than in those with osteoarthritis. Chronic infections, antibiotic use, or misdiagnosis may be contributing factors to unclear PJI diagnoses among culture-negative cases. This preliminary work supports the need for further studies to assess the differences in clinical features between culture-negative and culture-positive PJI in patients with inflammatory arthritis and the ability of biological diagnostic markers to discriminate between them in this population.

Do Antibiotic-Loaded Calcium Sulfate Beads Improve Outcomes After Debridement, Antibiotics, and Implant Retention? A Matched Cohort Study.

BACKGROUND: Dissolvable antibiotic-loaded calcium sulfate beads are used as an intraoperative adjunct during debridement with antibiotics and implant retention (DAIR) for periprosthetic joint infections (PJI) to reduce the historically higher failure rates than one- or two-stage exchange. This study evaluated clinical outcomes after DAIRs performed with and without these antibiotic beads. The primary outcome was post-DAIR failure secondary to recurrent PJI at 2 years. The secondary outcome was early failure secondary to recurrent PJI within 90 days. MATERIAL AND METHODS: DAIRs performed for acute or acute hematogenous PJI at a single institution were retrospectively identified between 2013 and 2018. All DAIRs with adjunctive antibiotic beads (cases) were then exactly matched to a cohort of DAIRs without beads (controls) based on Charlson Comorbidity Index. The McNemar's test and Wilcoxon signed-rank test were used to evaluate differences in outcomes and patient characteristics. RESULTS: Twenty DAIR cases (with antibiotic beads) were matched with 20 DAIR controls. There was no difference in age, sex, body mass index, joint, erythrocyte sedimentation rate, C-reactive protein, microbiology profile, antibiotic-resistance profile, or intraoperative lavage adjuncts between groups. There were no statistically significant differences between cases and controls for either overall infection-related failure at 2 years (P = .21) or early infection-related failure at 90 days (P = 1.00). CONCLUSION: Adjunctive dissolvable antibiotic-loaded calcium sulfate beads did not reduce the incidence of recurrent PJIs at 2 years or 90 days postoperatively after DAIR. Given the added cost of these antibiotic dissolvable beads without clinical benefits, we cannot recommend their use as an adjunct treatment during DAIRs.

Early Aseptic Loosening with Increased Presence and Severity of Backside Burnishing in the Optetrak Logic Posterior-Stabilized Total Knee Arthroplasty Femoral Component.

Concerns persist that the Optetrak Logic posterior-stabilized (PS) total knee arthroplasty (TKA) femoral component might correlate with early failures due to aseptic loosening. The primary aim of this study was to examine if the use of the Optetrak Logic PS femoral component is associated with early (<5 years) and more extensive aseptic loosening compared with other PS femoral components. This is a single-institution retrieval analysis and revision registry study (based on prospectively collected data) of 27 failed primary PS TKA patients with loose femoral components that underwent revision TKAs between 2016 and 2019. Patients were stratified by components type: Group A (n = 16) received the Optetrak Logic PS femoral component, while Group B (n = 11) received other PS femoral components. Burnishing (macroscopic polishing of the component's backside) was observed and graded as a marker for relative motion at the cement-implant interface. No significant differences were found between the two groups regarding the baseline demographic, radiographic, and clinical characteristics. Mean length of implantation for Group A (3.8 ± 2.9 years) was significantly shorter (p < 0.001) than that of Group B (12.0 ± 6.7 years). A significant difference (p = 0.009) was found in presence of backside femoral burnishing between Group A (15 of 16 patients; 93.8%) and group B (5 of 11 patients; 45.6%). Furthermore, we found a significant difference (p < 0.001) in the severity of burnishing between Group A (13 of 16 patients with severe degree of burnishing; 81.3%) and Group B (1 of 11 patients with severe degree of burnishing; 9.1%). In contrast to Group B, a distinctive macroscopic pattern found in Logic retrieved femoral components (Group A) was the total absence of cement in the backside surface. The use of the Optetrak Logic PS TKA femoral component was associated with early aseptic loosening and increased presence and severity of backside burnishing with early cement-implant interface debonding compared with other commercially available types of PS TKA femoral components. The earlier failure rate with this implant is of concern.

Serum Metal Ions in Contemporary Monoblock and Modular Dual Mobility Articulations.

BACKGROUND: Questions exist about the release of cobalt and chromium ions from dual mobility (DM) cups. Modular implants, with potential backside wear between the cobalt-chromium liner and titanium cup, are of particular concern. This study compares the metal ion profile of patients with contemporary monoblock and modular DM articulations from two commonly used designs. METHODS: Cobalt and chromium serum levels were measured one year after surgery in a prospective cohort of patients undergoing total hip arthroplasty with a DM construct. Ion levels were detected above 1 µg/L. Clinical and surgical data were correlated with the ion levels for analysis. RESULTS: Overall, 29% of the patients had levels above 1 µg/L of either ion. More patients with modular cups had detectable ions than patients with monoblock cups (39% vs 20%, P = .05). Cobalt was more commonly detected in the monoblock group, and chromium was more commonly detected in the modular group (P = .05). There were no differences in the actual ion levels between the groups (1.35 µg/L vs 1.64 µg/L, P = .44, for cobalt and 1.35 µg/L vs 1.31 µg/L, P = .77, for chromium). No patient underwent revision during the follow-up period. CONCLUSIONS: We found similar cobalt and chromium levels in patients with monoblock and modular DM cups. More patients in the modular group had detectable ions. Cobalt was more frequently detected in the monoblock group. These results suggest that both implants are performing well in the short term, but further follow-up is needed to determine whether the differences found are of clinical significance.