Minimal impact of beam projection angle deviations in skyline (Laurin) view and the efficacy of the anterior border of proximal tibia as a guiding landmark.

OBJECTIVE: Obtaining an optimal knee skyline view is challenging due to inaccuracies in beam projection angles (BPAs) and soft tissue obscuring bony landmarks. This study aimed to assess the impact of BPA deviations on patellofemoral index measurements and assessed the anterior border of the proximal tibia as an anatomic landmark for guiding BPAs. MATERIALS AND METHODS: This retrospective study consisted of three parts. The first was a simulation study using 52 CT scans of knees with a 20° flexion contracture to replicate the skyline (Laurin) view. Digitally reconstructed radiographs simulated neutral, 5° downward, and 5° upward tilt BPAs. Five patellofemoral indices (sulcus angle, congruence angle, patellar tilt angle, lateral facet angle, and bisect ratio) were measured and compared. The second part was a proof of concept study on 162 knees to examine patellar indices differences across these BPAs. Lastly, the alignment of the anterior border of the proximal tibia with the BPA tangential to the patellar articular surface was tested from the CT scans. RESULTS: No significant differences in patellofemoral indices were found across various BPAs in both the simulation and proof of concept studies (all p > 0.05). The angle between the anterior border of the proximal tibia and the patellar articular surface was 1.5 ± 5.3°, a statistically significant (p = 0.037) yet clinically acceptable deviation. CONCLUSION: Patellofemoral indices in skyline view remained consistent regardless of BPA deviations. The anterior border of the proximal tibia proved to be an effective landmark for accurate beam projection.

Shallow trochlear groove and narrow medial trochlear width at the proximal trochlea in patients with trochlear dysplasia: A three-dimensional computed tomography analysis.

PURPOSE: Although the Dejour classification is the primary classification system for evaluating trochlear dysplasia, concerns have been raised about its reliability owing to its qualitative criteria and challenges associated with obtaining accurate radiographs. This study aimed to quantify trochlear dysplasia using three-dimensional (3D) computed tomography (CT) reconstruction with novel parameters related to the transepicondylar axis (TEA). METHODS: Sixty patients were enrolled, including 20 with trochlear dysplasia and 40 healthy controls. The 3D CT model was generated using the Materialise Interactive Medical Image Control System software. The following six parameters were measured in eight consecutive planes at 15° intervals (planes 0-105): the distance from the TEA to the most cortical point of the lateral condyle ('LP-TEA', where LP stands for lateral peak), medial condyle ('MP-TEA', MP for medial peak) and deepest point of the trochlea ('TG-TEA', TG for trochlear groove). The distances from the medial epicondyle (MEC) to the corresponding TEA points were measured ('LP-MEC', 'MP-MEC' and 'TG-MEC'). RESULTS: In the dysplasia group, TG-TEA (planes 0, 15 and 30) and MP-MEC (planes 0, 15 and 30) were significantly greater than those in the control group (all p < 0.05 for planes of TG-TEA and MP-MEC). For type A dysplasia, LP-MEC (plane 0) was greater than that in the control group. For type B dysplasia, the MP-MEC (planes 0 and 15) and TG-TEA (planes 0 and 15) were greater than those of the control group. For type D dysplasia, MP-MEC (planes 0, 15 and 30) and TG-TEA (planes 0 and 15) were elevated. CONCLUSION: The 3D CT reconstruction analysis established a reproducible method for quantifying osseous trochlear morphology. Patients with trochlear dysplasia had a shallow TG and narrow medial trochlear width at tracking angles of 0°-30°. This finding corroborates the clinical manifestations of recurrent patellar instability that occur during early flexion. LEVEL OF EVIDENCE: Level III.

Mechanism of action of genicular artery embolization in a rabbit model of knee osteoarthritis.

OBJECTIVES: To establish a rabbit osteoarthritis model for genicular artery embolization (GAE) experiments and to investigate the cellular mechanism of action of this novel procedure for interventional radiologists. METHODS: Rabbit knee osteoarthritis was surgically modeled by anterior cruciate ligament transection and medial partial meniscectomy of the bilateral hindlimbs followed by 10 weeks of incubation. Rabbits exhibiting synovitis on magnetic resonance imaging were randomly divided into two groups: the bilateral GAE group and the control (sham procedure) group. Four weeks later, the rabbits' mobility (moving time, sec/10 min) and the histopathological features of each knee were assessed, and inter-group differences were evaluated using Student's t-test and ordinal/linear logistic models with generalized estimating equations. RESULTS: Osteoarthritis modeling and endovascular procedures were successful in 15 of 20 rabbits (8 and 7 in the GAE and control groups, respectively). There was no significant difference in moving times between the two groups (p = .958). The degree of structural cartilage damage was similar in both groups (p = .780). However, the synovial proliferation (p = .016), synovial hypertrophy (p < .001), and villous hyperplasia of the synovial stroma (p = .002) scores were significantly lower in the GAE group than in the control group. The CD3+ cell density (p = .018) and CD3 + cell-infiltrated area (p = .019) were also significantly lower in the GAE group than in the control group. CONCLUSION: GAE can limit inflammatory processes in the synovium of osteoarthritis-affected knees. KEY POINTS: Surgical transection of the anterior cruciate ligament and medial partial meniscectomy of rabbit knees provides a useful animal model for research of genicular artery embolization. Osteoarthritic knees treated by genicular artery embolization showed milder synovial proliferation (p = .016), synovial hypertrophy (p < .001), and villous hyperplasia of the synovial stroma (p = .002) than the untreated knees. Osteoarthritic knees treated by genicular artery embolization presented lower CD3+ cell density (p = .018) and CD3+ cell-infiltrated area (p = .019) in the synovium than the untreated knees.

Risk factors of de novo hyperextension developed after posterior cruciate ligament substituting total knee arthroplasty: a matched case-control study.

PURPOSE: To investigate factors contributing to the de novo hyperextension after posterior cruciate ligament substituting (PS) total knee arthroplasty (TKA). METHODS: Through a retrospective case-control study, de novo hyperextension patients were compared with patients without hyperextension after primary PS TKA. Eighty-five hyperextension patients were compared with 85 patients in a control group matched by age, sex, surgeon and implant. The clinical and radiographic parameters, including the mechanical axis (MA), joint line convergence angle (JLCA), posterior tibial slope angle (PTSA), posterior condylar offset (PCO), and the gamma angle, were evaluated preoperatively and immediate postoperatively. Comparisons between the two groups and logistic regression analysis were performed to investigate factors contributing to de novo hyperextension. RESULTS: Among the clinical factors, preoperative flexion contracture was less (5° ± 6° vs. 11° ± 6°, p < 0.001) and the range of motion was greater (125° ± 12° vs. 118° ± 5°, p = 0.041) in the de novo hyperextension group than in the control group. Among the radiographic parameters, preoperative and postoperative JLCA were greater (8.1° ± 4.4° vs. 6.1° ± 3.5°, p < 0.001, 1.0° ± 1.3° vs. 0.2° ± 0.8°, p = 0.002, respectively), postoperative PTSA was greater (3.7° ± 2.0° vs. 3.3° ± 1.6°, p < 0.001) and preoperative and postoperative PCO were less in the hyperextension group than in the control group (26.3 mm ± 3.3 mm vs. 29.1 mm ± 3.2 mm, p < 0.001, 26.4 mm ± 3.2 mm vs. 29.1 mm ± 3.0 mm, p < 0.001, respectively), whereas, change in PCO was greater in the hyperextension group (1.1 mm ± 7.7 mm vs. - 0.1 mm ± 3.3 mm, p < 0.001). In multivariate analysis, the degree of medial soft tissue release [odds ratio (OR) 2.83, p = 0.003], flexion contracture [OR 0.86, p = 0.028], postoperative JLCA [OR 2.45, p = 0.004], preoperative PCO and a change in PCO [OR 0.74, p = 0.002, OR 1.89, p = 0.001, respectively] were the factors associated with de novo hyperextension. CONCLUSIONS: An increased degree of medial soft tissue release, small preoperative flexion contracture, increased postoperative JLCA, decreased preoperative PCO and increased change in PCO were risk factors of de novo hyperextension. LEVEL OF EVIDENCE: III.

Subchondral insufficiency fracture is a predictive factor of osteoarthritis progression and conversion to arthroplasty in non-surgically treated medial meniscus root tear.

PURPOSE: To investigate the radiographic and clinical outcomes of non-surgical treatment for medial meniscus posterior root tear (MMPRT), and prognostic factors for osteoarthritis (OA) progression and clinical failure. METHODS: A prospectively collected database was retrospectively reviewed for patients who were diagnosed with acute medial meniscus posterior root tear (MMPRT) between 2013 and 2021 and treated non-surgically for more than 2 years. Patient demographic characteristics and clinical outcomes including pain numeric rating scale (NRS), International Knee Documentation Committee (IKDC) subjective score, Lysholm score, and Tegner activity scale were evaluated. For radiographic evaluation, knee radiographs were obtained to assess the angle of knee alignment and Kellgren-Lawrence (K-L) grade during the first and annually follow-up visits. Baseline magnetic resonance (MR) images were reviewed for the presence of medial meniscus extrusion, bone marrow edema, subchondral insufficiency fracture of medial femoral condyle, and cartilage lesion. The OA progression group was defined as patients who experienced a worsening of one or more grades in the K-L classification system. Prognostic factors were evaluated for OA progression and conversion to total knee arthroplasty (TKA). RESULTS: Ninety-four patients (90 female and 4 male) with a mean age of 67.0 ± 7.3 years (range, 53-83 years) were followed for a mean of 46.1 ± 22.1 months (range, 24.1-170.5). During the follow-up period, no significant differences in clinical scores were observed, and there were also no significant differences between the groups with and without OA progression. Overall, 12 patients (13%) underwent TKA at a mean of 20.7 ± 16.5 months (range, 8-69 months) and 34 patients (36%) demonstrated OA progression at a mean time of 24 ± 15 months (range, 12-62). The subchondral insufficiency fracture was a prognostic factor for OA progression (p = 0.045 for knee radiograph and p = 0.019 for MR) and conversion to TKA (RR, 4.08 [95% CI 1.23-13.57]; p = 0.022). CONCLUSIONS: Non-surgical treatment for acute medial meniscus posterior root tear did not result in any significant change in clinical outcomes from the initial to the final follow-up. The rate of conversion to arthroplasty was 13%, and the rate of osteoarthritis progression was 36%. Furthermore, subchondral insufficiency fracture was found to be a concomitant prognostic factor correlated with OA progression and conversion to arthroplasty. This information can provide insights for physicians when discussing treatment options with patients, particularly regarding the use of non-surgical treatment and may contribute as a source for future studies of medial meniscus posterior root tear. LEVEL OF EVIDENCE: IV.

Functional alignment with robotic­arm assisted total knee arthroplasty demonstrated better patient-reported outcomes than mechanical alignment with manual total knee arthroplasty.

PURPOSE: Given the improved accuracy of robot-assisted surgery, robotic-arm assisted functionally aligned total knee arthroplasty (RFA-TKA) aims to preserve the native pre-arthritic knee biomechanics, to achieve balanced flexion-extension gaps. The purpose of this study was to compare the accuracy of the implant position and short-term clinical outcomes of patients who underwent RFA-TKA vs. mechanically aligned total knee arthroplasty with manual technique (MA-TKA). METHODS: A prospectively collected database was reviewed retrospectively for patients who underwent primary TKA. Sixty patients who underwent RFA-TKA between February 2020 and July 2020 were included in the RFA-TKA group. Sixty patients who underwent MA-TKA were included via 1:1 matching for age, sex, and body mass index based on the RFA-TKA group. For radiological evaluation, knee X-rays were used to assess the functional knee phenotype and implant position accuracy by measuring the coronal and sagittal alignment, and these measurements were compared between the two groups. Patient demographic characteristics and patient-reported outcomes including Knee Society scores, Western Ontario and McMaster Universities Arthritis Index, and forgotten joint score-12 were compared between the groups. RESULTS: Statistically significant differences were observed in postoperative 2-year clinical outcomes in favor of RFA-TKA group which showed greater accuracy in the tibial component sagittal alignment than MA-TKA (1.0 ± 2.3 vs. 0.7 ± 1.6, respectively; P < 0.001). However, outliers in the component positions were more common in the MA-TKA group, which was statistically significant for the femoral coronal and tibial sagittal alignments (P = 0.017 and 0.015, respectively). CONCLUSIONS: Functional alignment in TKA could be accurately obtained with the assistance of a robotic arm, and the results showed greater 2 year postoperative patient-reported outcome and satisfaction than mechanically aligned TKA using manual instruments. LEVEL OF EVIDENCE: III.

Deep learning-based landmark recognition and angle measurement of full-leg plain radiographs can be adopted to assess lower extremity alignment.

PURPOSE: Evaluating lower extremity alignment using full-leg plain radiographs is an essential step in diagnosis and treatment of patients with knee osteoarthritis. The study objective was to present a deep learning-based anatomical landmark recognition and angle measurement model, using full-leg radiographs, and validate its performance. METHODS: A total of 11,212 full-leg plain radiographs were used to create the model. To train the data, 15 anatomical landmarks were marked by two orthopaedic surgeons. Mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), joint line convergence angle (JLCA), and hip-knee-ankle angle (HKAA) were then measured. For inter-observer reliability, the inter-observer intraclass correlation coefficient (ICC) was evaluated by comparing measurements from the model, surgeons, and students, to ground truth measurements annotated by an orthopaedic specialist with 14 years of experience. To evaluate test-retest reliability, all measurements were made twice by each measurer. Intra-observer ICCs were then derived. Performance evaluation metrics used in previous studies were also derived for direct comparison of the model's performance. RESULTS: Inter-observer ICCs for all angles of the model were 0.98 or higher (p < 0.001). Intra-observer ICCs for all angles were 1.00, which was higher than that of the orthopaedic specialist (0.97-1.00). Measurements made by the model showed no significant systemic variation. Except for JLCA, angles were precisely measured with absolute error averages under 0.52 degrees and proportion of outliers under 4.26%. CONCLUSIONS: The deep learning model is capable of evaluating lower extremity alignment with performance as accurate as an orthopaedic specialist with 14 years of experience. LEVEL OF EVIDENCE: III, retrospective cohort study.

Long-Term Nonoperative Management is Associated With Lower Mean 9-Year Follow-Up Survival Compared to Total Knee Arthroplasty in Knee Osteoarthritis Patients-Survival Analysis of a Nationwide South Korean Cohort.

BACKGROUND: Total knee arthroplasty (TKA) and medications are both considered as a treatment for knee osteoarthritis. However, the impact of the TKA on long-term survival remains controversial. This study aimed to compare 9-year follow-up survival between a TKA group with a nonoperative medication group. METHODS: From 2007 to 2009, knee osteoarthritis patients were divided into TKA (N = 2,228) and nonoperative medication (N = 76,430) groups, and followed for up to 9 years. The hazard ratio (HR) and subdistribution HR (SHR) were derived from Cox proportional hazards regressions and Fine and Gray analyses, respectively. RESULTS: The TKA group had a significantly lower adjusted mortality rate (adjusted HR , 0.78, 95% confidence interval [CI], 0.68-0.9) than the nonoperative medication group. Dose-response relationship between medication possession ratio and mortalities for overall (adjusted HR , 1.02; 95% CI, 1.01-1.04) and cardiovascular (CV) death (adjusted SHR, 1.03; 95% CI, 1.01-1.05) was also found. Also, there were significant interactions that indicate stronger protective survival effects of the TKA in several covariates: age >75 years (P = .04 for overall; P = .009 for CV), hypertension (P = .006 for overall), and ischemic heart disease (P = .009 for CV). CONCLUSIONS: This study suggests that TKA patients had better mean 9-year follow-up survival than the nonoperative medication group after adjusting for baseline differences. For overall death, including CV death, adjusted mortality rates were higher in the medication group and showed a dose-response relationship. Specifically, the protective effect of the TKA for overall or CV deaths was found to be higher for age >75, hypertension, or ischemic heart disease patients. LEVEL OF EVIDENCE: III.

Anatomic Patellar Design Has No Clinical Superiority Over Dome Patellar Design in Total Knee Arthroplasty: A Randomized Clinical Trial.

BACKGROUND: Various patellar designs are used in total knee arthroplasty (TKA) for optimal management of patellofemoral pain. The aim of this study was to compare postoperative 2-year clinical outcomes of 3 patellar designs: medialized anatomic (MA), medialized dome (MD), and Gaussian dome (GD). METHODS: In this randomized controlled trial, 153 patients undergoing primary TKA from 2015 to 2019 were enrolled. Patients were allocated to 3 groups (MA, MD, and GD). Demographic characteristics, clinical variables including knee flexion angle and patient-reported outcome measures (Kujala score, Knee Society Scores, the Hospital for Special Surgery score, and The Western Ontario and McMaster Universities Arthritis Index), and complications were collected. Radiologic parameters including Blackburne-Peel ratio and patellar tilt angle (PTA) were measured. A total of 139 patients who completed postoperative follow-up for 2 years were analyzed. RESULTS: Knee flexion angle and patient-reported outcome measures did not statistically differ among the 3 groups (MA, MD, and GD). There were no extensor mechanism-related complications at any group. Group MA showed significantly higher mean values of postoperative PTA than group GD (0.1 ± 3.2 versus -1.8 ± 3.4, P = .011). Group GD (20.8%) had a tendency to have more outliers (over 5 degrees) in PTA than groups MA (10.6%) and MD (4.5%), although the differences were not statistically significant (P = .092). CONCLUSION: Anatomic patellar design was not clinically superior over dome design in TKA, showing comparable results in terms of clinical scores, complications, and radiographic indices.

Changes in the femoral varus and rotational profiles are correlated in women with varus osteoarthritic lower limbs.

INTRODUCTION: Previous studies have reported the relationship between coronal alignment of the lower limbs and the rotational profile of the femur and tibia. However, the relationship between coronal alignment of the femur and tibia and their rotational profiles in patients with varus osteoarthritic knees is unclear. METHODS: One hundred women with varus osteoarthritic knees (varus OA group) and 50 women with neutrally aligned lower limbs without osteoarthritis (non-OA group) were evaluated retrospectively. The coronal alignment and rotational profile of the femur and tibia were evaluated, and the correlation between coronal alignment and rotational profile was analyzed, respectively. RESULTS: The femoral anteversion, posterior condylar angle of the distal femur, and tibial torsion were significantly smaller in the varus OA group than in the non-OA group. In the varus OA group, the femoral anteversion and rotational profile of the distal femur had significantly negative correlations with the degree of femoral varus, while tibial torsion was not related to the degree of tibial varus. In the non-OA group, there was no relationship between coronal alignment and rotational profiles of the femur and tibia in both the varus OA and non-OA groups. CONCLUSION: Femoral anteversion and the rotational profile of the distal femur were negatively correlated with the degree of femoral varus in Asian women with varus osteoarthritic knees. This study enhanced the understanding of the relationship between changes in coronal alignment of the femur and tibia and their rotational profiles in patients with varus osteoarthritic lower limbs, although this study was limited by the small sample sizes and methodological quality.

Risk Factors and Clinical Outcomes of Osteotomy Plane Violation by D-Hole Screws in Medial Open Wedge High Tibial Osteotomy: A Simulation and Comparative Study.

Background and Objectives: Stable fixation is essential for successful healing after medial open wedge high tibial osteotomy (MOWHTO) to minimize the risk of non-union and correction loss. In Asians, potential complications such as D-hole screw osteotomy plane violation (D-hole violation) and inadequate plate fitting arise due to improper plate size. This study aimed to evaluate the risk factors for D-hole violation and compare the conventional anatomic (CA) plate with an individualized anatomic (IA) plate in MOWHTO procedures. Materials and Methods: A simulation study on D-hole violation using the CA plate was conducted, involving preoperative radiographs and CT scans of 64 lower extremities from 47 MOWHTO patients. Additionally, a randomized controlled study compared CA and IA plates in MOWHTO procedures with 34 patients (17 in the CA plate group; 18 in the IA plate group). Patient demographics, patient-reported outcome measures (PROMs), and radiological measures were analyzed. Results: In the simulation study, the rates of D-hole violation ranged from 20.3% to 59.4%, with an increase observed as the plate was distalized from 5 mm to 10 mm away from the joint line. Short stature was identified as an independent risk factor for D-hole violation (p < 0.001), with a cutoff value of 155.3 cm. In the randomized controlled study, no significant difference in PROMs and D-hole violation was observed between the CA plate and IA plate groups. However, the IA plate group showed better plate fitting compared to the CA plate group (p = 0.041). Conclusions: This study identified a high risk of D-hole screw osteotomy plane violations in MOWHTO procedures, particularly when the plate is positioned more distally and in individuals with a stature below 155.3 cm. It also revealed that individualized plates provide better tibial fitting compared to conventional anatomic plates, particularly in Asian populations where tibial morphology tends to be shorter than in Western populations. Therefore, evaluating patient stature and selecting tailored plates are essential to optimize plate positioning and minimize plate-related complications in MOWHTO procedures.

Nanopore 16S amplicon sequencing enables rapid detection of pathogen in knee periprosthetic joint infection.

OBJECTIVES: We investigated whether nanopore 16S amplicon sequencing is capable of bacterial identification in patients with knee prosthetic joint infection (PJI), and we compared its efficacy with conventional culture studies. METHODS: In total, 36 patients who had clinical manifestation suspected of PJI were enrolled in this study. To begin, synovial fluids were aspirated from the affected knee using aseptic technique and tissues specimens were obtained during the surgery. Next, DNA was extracted from the synovial fluid or tissues, and 16S rDNA PCR was performed. In PCR positive cases, nanopore amplicon sequencing was then performed for up to 3 h. The results of amplicon sequencing were compared to those of conventional culture studies. RESULTS: Of the 36 patients enrolled, 22 were classified as true infections according to the MSIS criteria whereas 14 were considered uninfected. Among the 22 PJI cases, 19 cases were culture positive (CP-PJI) while three cases were culture negative (CN-PJI). In 14 of 19 (73.7 %) CP- PJI cases, 16S sequencing identified concordant bacteria with conventional culture studies with a significantly shorter turnaround time. In some cases, nanopore 16S sequencing was superior to culture studies in the species-level identification of pathogen and detection of polymicrobial infections. Altogether, in the majority of PJI candidate patients (32 of 36, 88.9 %), 16S sequencing achieved identical results to cultures studies with a significantly reduced turnaround time (100.9 ± 32.5 h vs. 10.8 ± 7.7 h, p < 0.001). CONCLUSIONS: Nanopore 16S sequencing was found to be particularly useful for pathogen identification in knee PJI. Although the sensitivity was not superior to culture studies, the nanopore 16S sequencing was much faster, and species-level identification and detection of polymicrobial infections were superior to culture studies.

A machine-learning model to predict postoperative delirium following knee arthroplasty using electronic health records.

BACKGROUND: Postoperative delirium is a challenging complication due to its adverse outcome such as long hospital stay. The aims of this study were: 1) to identify preoperative risk factors of postoperative delirium following knee arthroplasty, and 2) to develop a machine-learning prediction model. METHOD: A total of 3,980 patients from two hospitals were included in this study. The model was developed and trained with 1,931 patients from one hospital and externally validated with 2,049 patients from another hospital. Twenty preoperative variables were collected using electronic hospital records. Feature selection was conducted using the sequential feature selection (SFS). Extreme Gradient Boosting algorithm (XGBoost) model as a machine-learning classifier was applied to predict delirium. A tenfold-stratified area under the curve (AUC) served as the metric for variable selection and internal validation. RESULTS: The incidence rate of delirium was 4.9% (n = 196). The following seven key predictors of postoperative delirium were selected: age, serum albumin, number of hypnotics and sedatives drugs taken preoperatively, total number of drugs (any kinds of oral medication) taken preoperatively, neurologic disorders, depression, and fall-down risk (all p < 0.05). The predictive performance of our model was good for the developmental cohort (AUC: 0.80, 95% CI: 0.77-0.84). It was also good for the external validation cohort (AUC: 0.82, 95% CI: 0.80-0.83). Our model can be accessed at https://safetka.connecteve.com . CONCLUSIONS: A web-based predictive model for delirium after knee arthroplasty was developed using a machine-learning algorithm featuring seven preoperative variables. This model can be used only with information that can be obtained from pre-operative electronic hospital records. Thus, this model could be used to predict delirium before surgery and may assist physician's effort on delirium prevention.

Low muscle mass is an independent risk factor for postoperative blood transfusion in total knee arthroplasty: a retrospective, propensity score-matched cohort study.

BACKGROUND: Sarcopenia, an age-related loss of skeletal muscle mass and function, is correlated with adverse outcomes after some surgeries. This study examined the characteristics of sarcopenic patients undergoing primary total knee arthroplasty (TKA), and identified low muscle mass as an independent risk factor for postoperative TKA complications. METHODS: A retrospective cohort study examined 452 patients who underwent TKA. The skeletal muscle index (SMI) was obtained via bioelectrical impedance analysis (BIA), along with demographics, the Charlson Comorbidity Index, and medication, laboratory and operative data for 2018-2021. Patients were categorized into normal (n = 417) and sarcopenic (n = 35) groups using the SMI cut-off suggested by the Asian Working Group for Sarcopenia 2019 (males, < 7.0 kg/m2; females, < 5.7 kg/m2). Three postoperative complications were analysed: blood transfusion, delirium, and acute kidney injury (AKI). Baseline characteristics were propensity score-matched to address potential bias and confounding factors. RESULTS: The proportion of sarcopenic patients in primary TKA was 7.7% (35/452). The sarcopenic group had a lower preoperative haemoglobin (12.18 ± 1.20 vs. 13.04 ± 1.73 g/dL, p = 0.004) and total protein (6.73 ± 0.42 vs. 7.06 ± 0.44 mg/dL, p = 0.001). Propensity scoring matching and logistic regression showed that more patients in the sarcopenic group received postoperative blood transfusions (OR = 6.60, 95% CI: 1.57-45.5, p = 0.021); there was no significant difference in AKI or delirium. Univariate receiver operating characteristic curve analysis of the propensity-matched group, to determine the predictive value of SMI for postoperative transfusion, gave an AUC of 0.797 (0.633-0.96) and SMI cut-off of 5.6 kg/m2. CONCLUSIONS: Low muscle mass determined by BIA was an independent risk factor for postoperative transfusion in TKA. Multifrequency BIA can serve as a screening tool for sarcopenia that may influence the orthopaedic decision-making process or treatment planning in patients with sarcopenia undergoing primary TKA. LEVEL OF EVIDENCE: III, retrospective cohort study.

Variability between the trial and final implant measurements during the sensor-guided total knee arthroplasty.

PURPOSE: Compartmental load-sensing technology has been used in the attempt to achieve optimal soft tissue balance during total knee arthroplasty (TKA). This study was conducted to investigate the validity of such use of intraoperative sensing technology. METHODS: Ninety-three knees scheduled to undergo total knee arthroplasty for knee osteoarthritis with a tibial sensor were prospectively enrolled. Measurements were divided into three groups according to the three different time points of intraoperative load testing: group Trial (with the trial components), group Final (with the definitive cemented implants and an open joint capsule), and group Closed (with the definitive cemented implants and a closed joint capsule). Load measurements and component rotational alignments were documented at 10°, 30°, 45°, 90°, and 120° of flexion for all three groups, and compared. One year postoperatively, the joint line obliquity angle was obtained radiographically in the valgus and varus stress views at 10° and 30° flexion to evaluate the clinical instability. The Knee Society, Hospital for Special Surgery, and Western Ontario McMaster Universities Osteoarthritis Index scores were used to determine functional outcomes. The correlations of the above outcomes with intraoperative load were evaluated. RESULTS: There were significant differences in medial and lateral loads at all flexion angles (except at a 120° lateral load) between group Trial and group Final (p < 0.05). Tibial trays were internally rotated to a significantly higher degree in group Final than in group Trial (p = 0.010). The lateral compartmental load significantly decreased after patellar inversion (p = 0.037). There were no correlations of intraoperative load with clinical instability and functional outcomes. CONCLUSION: Significant variability was observed between the trial and final implant measurements and intraoperative sensing data were not correlated with instability or functional outcomes over a 1-year period. Therefore, intraoperative sensor technology provides limited feedback and clinical efficacy in the adjustment of the soft tissue balance during TKA. LEVEL OF EVIDENCE: Level II.

A web-based machine-learning algorithm predicting postoperative acute kidney injury after total knee arthroplasty.

PURPOSE: Acute kidney injury (AKI) is a deleterious complication after total knee arthroplasty (TKA). The purposes of this study were to identify preoperative risk factors and develop a web-based prediction model for postoperative AKI, and assess how AKI affected the progression to ESRD. METHOD: The study included 5757 patients treated in three tertiary teaching hospitals. The model was developed using data on 5302 patients from two hospitals and externally validated in 455 patients from the third hospital. Eighteen preoperative variables were collected and feature selection was performed. A gradient boosting machine (GBM) was used to predict AKI. A tenfold-stratified area under the curve (AUC) served as the metric for internal validation. Calibration was performed via isotonic regression and evaluated using a calibration plot. End-stage renal disease (ESRD) was followed up for an average of 41.7 months. RESULTS: AKI develops in up to 10% of patients undergoing TKA, increasing the risk of progression to ESRD. The ESRD odds ratio of AKI patients (compared to non-AKI patients) was 9.8 (95% confidence interval 4.3-22.4). Six key predictors of postoperative AKI were selected: higher preoperative levels of creatinine in serum, the use of general anesthesia, male sex, a higher ASA class (> 3), use of a renin-angiotensin-aldosterone system inhibitor, and no use of tranexamic acid (all p < 0.001). The predictive performance of our model was good (area under the curve 0.78 [95% CI 0.74-0.81] in the developmental cohort and improved in the external validation cohort (0.89). Our model can be accessed at https://safetka.net . CONCLUSIONS: A web-based predictive model for AKI after TKA was developed using a machine-learning algorithm featuring six preoperative variables. The model is simple and has been validated to improve both short- and long-term prognoses of TKA patients. Postoperative AKI may lead to ESRD, which surgeons should strive to avoid. LEVEL OF EVIDENCE: Diagnostic level II.

Spacer Block Technique Was Superior to Intramedullary Guide Technique in Coronal Alignment of Femoral Component after Fixed-Bearing Medial Unicompartmental Knee Arthroplasty: A Case-Control Study.

Backgrounds and Objectives: The spacer block technique in unicompartmental knee arthroplasty (UKA) has still a concern related to the precise position of the component in the coronal and sagittal planes compared to intramedullary guide technique. The purposes of this study were to explore whether the spacer block technique would improve the radiological alignment of implants and clinical outcomes compared with the outcomes of the intramedullary guide technique in fixed-bearing medial UKA. Materials and Methods: In total, 115 patients who underwent unilateral, fixed-bearing medial UKA were retrospectively reviewed and divided into group IM (intramedullary guides; n = 39) and group SB (spacer blocks; n = 76). Clinical assessment included range-of-motion and patient-reported outcomes. Radiological assessment included the mechanical femorotibial angle, coronal and sagittal alignments of the femoral and tibial components, and coronal femorotibial congruence angle. Results: All clinical outcomes showed no significant differences between groups. The coronal femoral component angle was valgus 2.4° ± 4.9° in IM group and varus 1.1° ± 3.2° (p < 0.001). In group IM, the number of outlier in coronal femoral component angle (<−10° or 10°<) was 3 cases, while in group SB, there was no outlier (p = 0.014). The coronal femorotibial congruence angle was significantly less in group SB (mean 1.9°, range, −3.2°~8.2°) than in group IM (mean 3.4°, range, −9.6°~16.5°) (p = 0.028). Conclusions: In the group SB, the coronal alignment of femoral component was closer to neutral, and outlier was less frequent than in the group IM. The spacer block technique was more beneficial in achieving proper coronal alignment of the femoral component and congruence of femorotibial components compared to the intramedullary guide technique in fixed-bearing medial UKAs.

Automated Detection of Surgical Implants on Plain Knee Radiographs Using a Deep Learning Algorithm.

Background and Objectives: The number of patients who undergo multiple operations on a knee is increasing. The objective of this study was to develop a deep learning algorithm that could detect 17 different surgical implants on plain knee radiographs. Materials and Methods: An internal dataset consisted of 5206 plain knee antero-posterior X-rays from a single, tertiary institute for model development. An external set contained 238 X-rays from another tertiary institute. A total of 17 different types of implants including total knee arthroplasty, unicompartmental knee arthroplasty, plate, and screw were labeled. The internal dataset was approximately split into a train set, a validation set, and an internal test set at a ratio of 7:1:2. You Only look Once (YOLO) was selected as the detection network. Model performances with the validation set, internal test set, and external test set were compared. Results: Total accuracy, total sensitivity, total specificity value of the validation set, internal test set, and external test set were (0.978, 0.768, 0.999), (0.953, 0.810, 0.990), and (0.956, 0.493, 0.975), respectively. Means ± standard deviations (SDs) of diagonal components of confusion matrix for these three subsets were 0.858 ± 0.242, 0.852 ± 0.182, and 0.576 ± 0.312, respectively. True positive rate of total knee arthroplasty, the most dominant class of the dataset, was higher than 0.99 with internal subsets and 0.96 with an external test set. Conclusion: Implant identification on plain knee radiographs could be automated using a deep learning technique. The detection algorithm dealt with overlapping cases while maintaining high accuracy on total knee arthroplasty. This could be applied in future research that analyzes X-ray images with deep learning, which would help prompt decision-making in clinics.

A high degree of knee flexion after TKA promotes the ability to perform high-flexion activities and patient satisfaction in Asian population.

BACKGROUND: This study investigated whether achieving a higher degree of knee flexion after TKA promoted the ability to perform high-flexion activities, as well as patient satisfaction and quality of life. METHODS: Clinical data on 912 consecutive primary TKA cases involving a single high-flexion posterior stabilized fixed-bearing prosthesis were retrospectively analyzed. Demographic and clinical data were collected, including knee flexion angle, the ability to perform high-flexion activities, and patient satisfaction and quality of life. RESULTS: Of the cases, 619 (68%) achieved > 130° of knee flexion after TKA (high flexion group). Knee flexion angle and clinical scores showed significant annual changes, with the maximum improvement seen at 5 years and slight deterioration observed at 10 years postoperatively. In the high flexion group, more than 50% of the patients could not kneel or squat, and 35% could not stand up from on the floor. Multivariate analysis revealed that > 130° of knee flexion, the ability to perform high-flexion activities (sitting cross-legged and standing up from the floor), male gender, and bilateral TKA were significantly associated with patient satisfaction after TKA, while the ability to perform high-flexion activities (sitting cross-legged and standing up from the floor), male gender, and bilateral TKA were significantly associated with patient quality of life after TKA. CONCLUSIONS: High knee flexion angle (> 130°) after TKA increased the ease of high-flexion activities and patient satisfaction. The ease of high-flexion activities also increased quality of life after TKA in our Asian patients, who frequently engage in these activities in daily life.

Efficacy of intra-operative administration of iron isomaltoside for preventing postoperative anaemia after total knee arthroplasty: A randomised controlled trial.

BACKGROUND: Postoperative anaemia is common after total knee arthroplasty (TKA). Emerging evidence shows the beneficial effects of peri-operative iron supplementation in patients at risk of postoperative anaemia. OBJECTIVE: To evaluate the efficacy of intra-operative administration of iron isomaltoside for the prevention of postoperative anaemia in patients undergoing TKA. DESIGN: Randomised, controlled, double-blind, parallel-group study. SETTING: A tertiary care teaching hospital; between 29 March 2018 and 16 April 2019. PATIENTS: Eighty-nine patients scheduled for unilateral TKA were included. INTERVENTION: Iron isomaltoside or placebo were administered intravenously over 30 min during surgical wound closure. MAIN OUTCOME MEASURES: The primary outcome measure was the incidence of anaemia at 30 days after TKA: anaemia was defined as haemoglobin less than 12 g dl-1 for female and less than 13 g dl-1 for male. RESULTS: In total, 89 patients were included in the final analysis (44 in the treatment group; 45 in the control group). The administered dose of iron isomaltoside in the treatment group was 1136 ±â€Š225 mg. The incidence of anaemia at 30 days after TKA was significantly lower in the treatment group (34.1%, 15/44) than that in the control group (62.2%, 28/45): relative risk 0.55 (95% confidence interval, 0.34 to 0.88), P = 0.008. Haemoglobin concentration, serum ferritin concentrations, and transferrin saturation were also significantly higher in the treatment group at 30 days after TKA. CONCLUSION: The intra-operative administration of iron isomaltoside effectively prevents postoperative anaemia in patients undergoing TKA, and thus it can be included in patient blood management protocols for reducing postoperative anaemia in these population. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT03470649.