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Background: The long-term goal of anterior cruciate ligament (ACL) reconstruction is to prevent secondary osteoarthritis due to instability. Obesity itself is also a risk factor for osteoarthritis and shows an increase in its incidence, but little is known about the relationship between obesity and the outcome of ACL reconstruction. Purpose/Hypothesis: This study aimed to determine the relationship between the outcome of ACL reconstruction and obesity. It was hypothesized that obesity would be associated with the revision rate of ACL reconstruction and additional surgical treatment for osteoarthritis in patients who undergo ACL reconstruction. Study design: Cohort study; Level of evidence, 3. Methods: Claims and health screening data of the National Health Insurance Service were used to analyze patients who underwent ACL reconstruction between January 1, 2003, and December 31, 2021. The association between obesity and risk of revision ACL reconstruction and additional surgical treatment for osteoarthritis or meniscal lesion was analyzed. Body mass index (BMI) was used to classify patients as underweight (BMI, <18.5), normal weight (BMI, 18.5-24.9), overweight (BMI, 25.0-29.9), obese (BMI, 30.0-39.9), or morbidly obese (BMI, ≥40.0). Multivariable Cox proportional hazards model analysis was conducted. Results: A total of 56,734 patients were included. Of them, 311 (0.5%) patients were underweight, 26,613 (46.9%) were normal weight, 24,372 (43.0%) were overweight, 5324 (9.4%) were obese, and 114 (0.2%) patients were morbidly obese. The underweight group showed a significantly lower risk of revision ACL reconstruction than the normal weight group (hazard ratio [HR], 0.54; 95% CI, 0.31-0.93; P =.0273). However, the overweight, obese, and morbidly obese groups had no significant difference from the normal weight group. The risk of high tibial osteotomy (HTO) or total knee arthroplasty (TKA) was significantly high for the overweight (HR, 1.93; 95% CI, 1.70-2.19; P <.0001) and obese (HR, 2.71; 95% CI, 2.23-3.30; P <.0001) groups. Subgroup analysis performed in patients ≥40 years of age for the risk of HTO showed a significant increased risk in the overweight group (HR, 1.889; 95% CI, 1.56-2.29; P <.0001) and obese group (HR, 2.78; 95% CI, 2.10-3.69; P <.0001). Subgroup analysis performed in patients ≥50 years of age for the risk of TKA also showed a significant increased risk in the overweight group (HR, 2.03; 95% CI, 1.67-2.47; P <.0001) and obese group (HR, 2.53; 95% CI, 1.83-3.50; P <.0001). After adjusting for meniscal injury at index surgery by multivariate regression analysis, 1.87- and 2.75-fold increased risks of HTO were identified for the overweight and obese groups, respectively, for patients aged >40 years. For patients aged >50 years, 2.02-fold and 2.52-fold increased risks of TKA were observed for the overweight and obese groups, respectively. The risk of additional surgery due to the meniscal lesion was high for the overweight (HR, 1.09; 95% CI, 1.03-1.15; P =.002) and obese (HR, 1.10; 95% CI, 1.01-1.21; P =.0351) groups, while no significant difference was found for the underweight and morbidly obese groups. Conclusion: This study highlights that obesity does not increase the revision rate of ACL reconstruction. However, the risk of additional surgical treatment for osteoarthritis and meniscal lesions increased as BMI increased. Further investigation is needed to determine the efficacy of ACL reconstruction for preventing osteoarthritis in obese patients. [ABSTRACT FROM AUTHOR]

Introduction: Early diagnosis and aggressive treatment of pulmonary embolism (PE) are crucial for preventing severe complications after total knee arthroplasty (TKA). This study aimed to examine the efficacy of measuring oxygen saturation (SpO2) using a pulse oximeter for early diagnosis of PE after total knee arthroplasty (TKA). Materials and methods: We consecutively examined 1645 patients who underwent TKA between January 2015 and November 2019. Postoperative SpO2 was measured with a pulse oximeter, which was stopped if SpO2 was maintained at ≥ 95% until postoperative day 2 (POD2). To diagnose PE, computed tomographic pulmonary angiography (CTPA) was performed for specific indications, including persistently low SpO2 < 95% (group 1), sudden decrease in SpO2 (group 2), and decrease in SpO2 after POD3 with presenting symptoms (group 3). Also, we divided the patients into unilateral, simultaneous and sequential TKA groups and compared the results with specific statistical techniques. Results: Of the 1645 patients who underwent TKA, there were 20 patients with PE (1.2%), and symptomatic PE was observed in only 4 patients (0.24%). CTPA was performed in 58 (3.5%) patients, of whom 20 were diagnosed with PE. In groups 1 (n = 34), 2 (n = 21), and 3 (n = 3), CTPA was performed 2.4, 2.6, and 8.3 days after TKA, respectively, and 12, 8, and 0 patients were diagnosed with PE, respectively. Of the 782, 416, and 447 unilateral, simultaneous, and sequential (done in same admission with interval 1 or 2 weeks) patients with TKA, 38, 18, and 2 received CTPA, and 13, 6, and 1 were diagnosed with PE, respectively. All patients diagnosed with PE have persistently low SpO2 < 95% (group 1), or sudden decrease in SpO2 (group 2) until POD2. Of the patients diagnosed with PE, SpO2 decreased without the presentation of symptoms in 16 patients (11 and 5 from groups 1 and 2, respectively) and with the presentation of symptoms, such as mild dyspnea and chest discomfort, in 4 patients (1 and 3 from groups 1 and 2, respectively). Conclusions: Measuring SpO2 using a pulse oximeter until POD2 was an effective method for early diagnosis of PE after TKA. No case of morbidity or mortality was observed after early diagnosis with early stage CTPA and management of PE. We recommend measuring SpO2 with a pulse oximeter for early diagnosing of PE in TKA. [ABSTRACT FROM AUTHOR]

Periprosthetic joint infection (PJI) remains among the most challenging and costly complications. PJI rates vary from 0.39% to 3.9% after total knee arthroplasty (TKA). This study aimed to identify the causative microorganisms involved and to report our experience of subsequent treatment of PJI following over 7000 TKAs performed over 19 years. A retrospective study was conducted on 4547 patients (7019 cases) from March 2000 to September 2019. The incidence rate of PJI was 0.5%. Gram-positive bacteria accounted for 88.8% (n = 16) of the 18 cases, and S. aureus was the most commonly isolated pathogen (n = 7, 38.8%). There were six cases of MSSA and one case of MRSA. Streptococcus species (n = 7, 38.8%) also showed the same pattern. The CoNS species (n = 2, 11.1%) and Gram-negative bacteria (n = 1, 5.5%) were also reported. Candida species were isolated from 1 patient (5.5%). Successful I&D and implant retention (DAIR procedures) was achieved at the final follow-up in 19 patients (82.6%). The incidence of causative microorganisms was different for each PJI onset type. The overall infection rate of PJI was less than 1%. Although the success rate of DAIR procedures is lower than the two-stage exchange arthroplasty in this study, it is possible to achieve acceptable success rates if DAIR procedures are carefully selected considering the virulence of the microorganism, duration since symptom onset, and early-onset infection. [ABSTRACT FROM AUTHOR]

This study aimed to analyze the rates and risk factors of postoperative mortality among 560,954 patients who underwent total knee arthroplasty (TKA) in Korea. The National Health Insurance Service-Health Screening database was used to analyze 560,954 patients who underwent TKA between 2005 and 2018. In-hospital, ninety-day, and one-year postoperative mortality, and their association with patient's demographic factors and various comorbidities (ie., cerebrovascular disease, congestive heart failure, and myocardial infarction) were assessed. In-hospital, ninety-day and one-year mortality rates after TKA were similar from 2005 to 2018. The risk of in-hospital mortality increased with comorbidities like cerebrovascular disease (hazard ratio [HR] = 1.401; 95% confidence interval [CI] = 1.064–1.844), congestive heart failure (HR = 2.004; 95% CI = 1.394 to 2.881), myocardial infarction (HR = 2.111; 95% CI = 1.115 to 3.998), and renal disease (HR = 2.641; 95% CI = 1.348–5.173). These co-morbidities were also independent predictors of ninety-day and one-year mortality. Male sex and old age were independent predictors for ninety-day and one-year mortality. And malignancy was risk factor for one-year mortality. The common preoperative risk factors for mortality in all periods were male sex, old age, cerebrovascular disease, congestive heart failure, myocardial infarction, and renal disease. Malignancy was identified as risk factor for one-year mortality. Patients with these comorbidities should be provided better perioperative care. [ABSTRACT FROM AUTHOR]

Purpose: Pseudo-patella baja (PPB) is a surgical complication that can arise from total knee arthroplasty and occurs when the patella tendon is not shortened but the level of the femorotibial joint line is elevated. The goal of this study was to assess the performance of a technique specifically designed to prevent the occurrence of PPB and its radiological results.Methods: Ninety-nine patients undergoing total knee arthroplasty were included. Patients were divided into a non-correction group and a correction group. The correction group were applied an additional metal block in order to reduce the excess resection of the distal femur. To evaluate PPB, the change in the pre- and postoperative joint line was measured using the modified Blackburne-Peel Index (BPI).Results: In the non-correction group, 68 of 74 cases showed an occurrence of PPB (92 %), in the correction group, 6 of 57 cases showed an occurrence of PPB (11 %). The preoperative-modified BPI of the non-correction group was not significantly different from that of the correction group (0.6 ± 0.1 vs. 0.6 ± 0.2). The modified BPI decreased significantly in the non-correction group after TKA (0.6 ± 0.1 vs. 0.2 ± 0.1, p < 0.05). However, the modified BPI did not change significantly in the correction group after TKA (0.6 ± 0.2 vs. 0.6 ± 0.2).Conclusion: The comparison of preoperative and postoperative radiological results showed that our intervention maintained the joint line without elevation. We proposed an effective method to prevent various complications due to the joint line elevation that occur in PPB.Level Of Evidence: III. [ABSTRACT FROM AUTHOR]

Purpose: Reduction in blood loss during surgery stabilizes hemodynamic status and aids in recovery after total knee arthroplasty (TKA). In this study, the authors examined whether different administration routes of tranexamic acid (TNA) might affect the amount of blood loss after TKA. Methods: A total of 150 patients were prospectively allocated to each of the three groups (intravenous, intra-articular, and placebo group) and underwent unilateral TKA. During closing the operative wound, TNA (1.5 g mixed in 100 cc of saline) was administered intravenously or intra-articularly according to the enrolled group, and an equivalent volume of normal saline was administered into the knee joint cavity and intravenously in the placebo group, respectively. The amount of blood loss and transfusion, and changes in haemoglobin levels were documented accordingly. Results: The mean blood loss in the intravenous, intra-articular, and placebo groups were 528 ± 227, 426 ± 197, and 833 ± 412 ml, respectively. About 66 % (intravenous), 80 % (intra-articular), and 6 % (placebo) of each group did not require transfusion for any reason, and the mean amount of transfusion was 273.6, 129.6, and 920.8 ml, respectively. Preoperative haemoglobin values decreased by 1.6 ± 0.8, 1.8 ± 0.8, and 2.0 ± 0.9 mg/dl, respectively. Conclusion: Compared to intravenous administration, intra-articular administration of TNA seems to be more effective in terms of reducing blood loss and transfusion frequency. TNA may improve the general conditions of patients given TKA by maintaining a hemodynamically stable state, aiding in recovery, and reducing the chance of transfusion-associated side effects and complications. Level of evidence: II. [ABSTRACT FROM AUTHOR]

Purpose: Historically, extramedullary techniques have focused on finding the femoral head center and referred mainly to the anterosuperior iliac spine (the FHC method) in total knee arthroplasty (TKA). The purpose of this study was to evaluate a new extramedullary alignment system that uses neutral overall limb mechanical alignment as an extramedullary reference (the MA method). Methods: A retrospective review of 1018 TKAs (508 FHC group, 510 MA group) was performed to compare the radiographic results obtained using these two methods. There were 75 male patients and 577 female patients with varus osteoarthritis of the knee. Limb and prosthesis alignments in the coronal plane were investigated at 2 months after surgery. Results: The accuracies of postoperative alignments of implanted prostheses were better in the MA group than in the FHC group, as assessed by (1) overall limb alignment (MA group, varus 1.4° ± 2.7°; FHC group, varus 2.2° ± 2.9°), and (2) femoral component coronal alignment (MA group, 89.4° ± 2.3°; FHC group, 88.0° ± 2.7°). Overall limb alignment was within 0° ± 5° of the mechanical axis in 96.1% of the MA group and in 86.6% of the FHC group. Mean femoral component medial angle was within 0° ± 5° in 98.4% of the MA group and in 92.5% of the FHC group. Conclusion: The accuracies of the postoperative radiographic alignments of implanted prostheses were found to be improved when the mechanical axis of the overall lower limb was used as an extramedullary reference. This new reference system would help to achieve correct limb and prostheses alignments during TKA. Level of evidence: III. [ABSTRACT FROM AUTHOR]

Background and purpose Identification of the center of the femoral head in the coronal plane is essential during total knee arthroplasty. We evaluated a new method for localization of the center of the hip, thereby detecting the neutral mechanical axis using inter-femoral head center distances (X) measured from a radiograph. Our proposed method was compared with 3 commonly used methods using landmarks that are estimated to be 2 finger-breaths medial to the anterosuperior iliac spine (method A), 2.5 cm perpendicular to the mid-inguinal point (method I), and 1.5 cm lateral to the femoral artery (method F). Methods 114 patients undergoing total knee arthroplasty were prospectively enrolled in the study. Four landmarks were marked and conventional anterior-posterior pelvic radiographs were taken. On the radiograph, the distance between the estimated FHC and the neutral mechanical axis was measured. Results The median value (mm) of the measured distance was 9 in A, 7 in I, 8.5 in F, and 5 in X. When an error of more than 3° from neutral alignment was defined as an outlier, 15% of measurements in A, 6% of measurements in I, 14% in F, and 2% in X would fall in the outlier zone. Interpretation The method detecting the neutral mechanical axis using inter-femoral head center distances (X) showed the least variability and the lowest percentage of outliers. [ABSTRACT FROM AUTHOR]

A correction to the article "The Comparative Efficacies of Intra-Articular and IV Tranexamic Acid for Reducing Blood Loss During Total Knee Arthroplasty," published in a previous issue of the journal is presented.