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BACKGROUND: Lower limb coronal alignment was thought to be a predictive factor for Unicompartmental Knee Arthroplasty (UKA) result. The tibial bony resection and implant position lead to joint line change postoperatively. Analysis was done to find out the correlation between these factors. METHODS: From 2019 to 2021, 90 medial Oxford UKA were implanted by a single surgeon. Hip Knee Ankle Angle (HKAA), Lateral Distal Femoral Angle (LDFA), Medial Proximal Tibial Angle (MPTA), and intraoperative bony resection thickness were measured. The medial joint line change was calculated. The correlation between joint line change and alignment change was evaluated. RESULTS: The mean tibial resection thickness was 4.3 mm. The mean tibial joint line was elevated by 2.3 mm, while the mean femoral joint line proximalized by 0.8 mm. HKAA changed from 8.4° varus preoperatively to 3.6° varus postoperatively. LDFA changed from 89.0° to 86.7°. MPTA changed from 85.6° to 86.6°. Preoperative HKAA showed a strong correlation with postoperative HKAA (p < 0.001), and preoperative MPTA showed a positive correlation with postoperative HKAA (p < 0.001). While preoperative LDFA had a negative correlation with postoperative HKAA (p < 0.001). The femoral joint line change and LDFA change had a significant correlation with HKAA change (p < 0.05). CONCLUSION: The change of joint line had no correlation with postoperative HKAA in Oxford UKA. Preoperative HKAA strongly correlated with postoperative HKAA; while preoperative smaller LDFA and larger MPTA had a moderate correlation with postoperative HKAA. The femoral joint line change and LDFA change had a weak to moderate correlation with HKAA change.

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Aseptic loosening is a feared and not yet fully-understood complication of total knee arthroplasty (TKA). Hypersensitivity reactions may be the underlying cause within some susceptible patients. Metal-free implants have been developed as a possible solution. The aim of this prospective, observational long-term study was the assessment of a completely metal-free ceramic knee replacement system compared to its identical metal counterpart 8 years after implantation, conducted as a follow-up of a previous report. A total of 88 patients (mean age 69 years) were enrolled in this prospective, observational long-term 8-year follow-up study. The "ceramic group" with a completely metal-free total knee replacement system was compared to the "conventional group" with an identical metal TKA system at the final follow-up. Clinical assessment included Knee Society Score (KSS), Oxford Knee Score (OKS), European Quality of Life 5 Dimensions 3 Level Version (EQ-5D-L), European Quality of Life 5 Dimension Visual Analogue Scale (EQ-VAS) and High Activity Arthroplasty Score (HAAS) as well as perioperative or postoperative complications and need for revision. The tibial/femoral positioning, signs of periprosthetic fissures/fractures or radiolucent lines were documented radiographically. All postoperative clinical scores in the ceramic group primarily improved from baseline to 4-year follow-up, but then decreased at the final 8-year follow-up. At the final follow-up, statistically non-significant differences were found in comparison of both groups for the KSS (ceramic: 166 ± 31, conventional: 162 ± 29; p > 0.05), OKS (ceramic: 37, conventional: 39; p > 0.05), EQ-VAS (ceramic: 77 ± 17, conventional: 72 ± 18; p > 0.05), and HAAS (ceramic: 8.29 ± 3.32, conventional: 9.28 ± 4.44; p > 0.05). A significant difference was found for EQ-5D-L (ceramic: 0.819 ± 0.284, conventional: 0.932 ± 0.126; p ≤ 0.05). Progressive radiolucent lines have been found around the uncemented tibial stem (0.8 mm at initial diagnosis (mean 19 months); 1.3 mm at 4-year follow-up; 1.6 mm at 8-year follow-up) without any clinical signs of loosening. One revision surgery was performed after a traumatic polyethylene inlay-breakage. No allergic reactions could be detected. The used ceramic TKA system meets the functional performance standards of an established identical metal TKA system after an 8-year follow-up period, offering a safe option for patients with prior hypersensitivity reactions to metallic materials. Full cementation of ceramic components is recommended.

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BACKGROUND: The prevalence of noncemented total knee arthroplasty (TKA) is increasing as personalized knee alignment strategies deviate from implanting components on a strict mechanical axis. This retrospective study evaluated the outcomes of 74 consecutive noncemented unrestricted kinematic TKA procedures. METHODS: This study included 74 consecutive noncemented kinematic TKAs performed by one surgeon at a tertiary academic medical center from 2021 to 2023. The technique used was unrestricted femur-first caliper kinematic TKA. The outcomes included revision, pain scores, and radiographic measurements. RESULTS: Of the 74 procedures performed, there were no revisions or readmissions for problems related to TKA. The mean follow-up was 17.6 months, with 74% of patients being followed up for more than 1 year postoperatively. On the day of surgery, postoperative measurements showed that the average tibial mechanical, distal femoral, and anatomic tibiofemoral angles were 3.3°, 7.7°, and 5.8°, respectively. 5 knees were observed initially with signs of radiolucency, which all resolved by the most recent appointment. None of the knees was radiographically loose. Of the patients, 65%, 19%, and 16% reported no pain, minimal pain, and some pain, respectively, at the 6-week follow-up visit. This improved to 78%, 19%, and 3% at the most recent follow-up. CONCLUSION: Combining kinematic alignment with noncemented fixation showed excellent clinical and radiographic outcomes with short-term survivorship. Although the use of both kinematic alignment and noncemented TKAs has been controversial, these early data suggest that noncemented kinematic TKA is safe and effective.

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The objective of this study was to assess radiolucent lines (RLLs) and to determine their effect on clinical outcomes of the newly introduced cementless mobile-bearing total knee arthroplasty (TKA) system. This was prospective, multicentre study. Seventy-eight patients with knee osteoarthritis who underwent primary TKA were enrolled. Patient-reported outcome measures (PROMs) and radiographic assessments were evaluated at preoperative baseline and at 6 weeks, 1 year, and 2 years after surgery. KOOS, PKIP, 2011KSS, EQ-5D-3L and SKO improved from preoperative baseline to all postoperative timepoints, with no loosening of components. No RLLs were detected at 6 weeks after surgery. However, RLLs ≥ 1 mm developed in 2.8% of the patients for the femur and 9.7% for the tibia at 1 year after surgery, and values were 5.7% and 10.9%, respectively, at 2 years after surgery. RLL incidence was not correlated with PROMs. Age, sex, body mass index, range of motion knee flexion, posterior cruciate ligament treatment and ß angle did not impact the occurrence of RLLs. There were no intraoperative complications, revisions or reoperations. This TKA system improved PROMs and showed less incidence of RLLs compared to the previous reported TKA without implant-related complications.

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INTRODUCTION: In the evaluation of an internal analysis of data on the increased effort for nursing during rehabilitation of patients with amputations in the Baumrainklinik of the HELIOS Rehabilitation Center Bad Berleberg, the number of patients with transfemoral amputations (TFA) due to uncontrollable multiple infections after implantation of a total knee endoprosthesis (total knee arthroplasty, TKA) was clearly emphasized. OBJECTIVE: This article discusses the results of a retrospective, patient-controlled trial (PCT) and compares these with the data of the German Endoprosthesis Registry (EPRD). The study concentrated on patients who were admitted to rehabilitation after a TFA due to an uncontrollable infection after implantation of a knee TKA. The primary aims were the identification of patients who developed an uncontrollable infection after TKA with subsequent TFA and the comparison with national and international revision and amputation rates after TKA. METHOD: An analysis of the medical history questionnaire was carried out for all 787 patients with amputation of the lower extremities who underwent rehabilitation in the time period from 1st January 2007 to 31st December 2015. The patient records were systematically analyzed based on the standardized documentation methods of the medical and nursing personnel using the Barthel index, the activity/function classes, phantom pain and length of stay, including demography, infection history and insurance company. RESULTS: The analysis showed that 10 patients, 2.29% of all TFA, suffered the loss of a lower extremity due to an uncontrollable TKA infection. The revision rate 3 years after primary TKA in Germany is 3.0% (EPRD annual report 2023), whereas values of 1-4% are given in the international literature (status 2020). In the patient group of the EPRD, in 2022 revision surgery was necessary due to an infection in 15.0% of the cases. The current statistics of the EPRD (annual report 2023) show that 3 years after the initial revision surgery due to an infected TKA another revision was necessary in 23.5-30% of cases. CONCLUSION: These numbers are alarming and should be critically evaluated and monitored. The future aim is to identify the causes of infections, systematic errors in the TKA and the pathogens that lead to infections after TKA and to correlate the associations.

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OBJECTIVES: The study focused on the ability to predict the need and size of femoral and tibial augmentation using standard two-dimensional (2D) templates and models created with three-dimensional (3D) printing in surgical planning. PATIENTS AND METHODS: This observational cohort study included 28 consecutive patients (22 females, 6 males; mean age: 71±7.3 years; range, 54 to 82 years) with periprosthetic joint infection recruited between March 2021 and September 2023 undergoing revision total knee arthroplasty revision (TKA). Standard planning was made using calibrated X-ray images. The 3D planning started with computed tomography scans to generate a 3D template of the distal femur and proximal tibia. The model was exported to a 3D printer to produce a patient-specific phantom. The surgery was then simulated on the 3D phantom using revision knee arthroplasty instrumentation to evaluate the appropriate augmentation to use until a correct alignment was obtained. RESULTS: Three-dimensional planning predicted the need for femoral and tibial augments in 22 (78.6%) cases at both the tibial and femoral components, while 2D planning correctly predicted the need for augmentation in 17 (60.7%) for the tibial side and 18 (64.3%) for the femoral side. The Cohen's kappa demonstrated a significant agreement between the 3D planning for the femoral metal block and the intraoperative requirement (kappa=0.553), whereas 2D planning showed only nonsignificant poor agreement (kappa=0.083). In contrast, the agreement between 2D or 3D preoperative planning for tibial augment and the intraoperative requirement was nonsignificant (kappa=0.130 and kappa=0.158, respectively). On the femoral side, 2D planning showed only a fair nonsignificant correlation (r=0.35, p=0.069), whereas 3D planning exhibited substantial agreement with the actual thickness of the implanted augment (r=0.65, p<0.001). On the tibial side, 3D and 2D planning showed substantial agreement with the actual size of implanted augments (3D planning, r=0.73, p<0.001; 2D planning, r=0.69, p<0.001). CONCLUSION: Prediction based on 3D computed tomography segmentation showed significant agreement with the intraoperative need for augmentations in revision TKA. The results suggest that planning with 3D printed models represents a stronger aid in this kind of surgery rather than standard 2D planning, providing greater accuracy in the prediction of the required augmentation in revision TKA.

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This prospective bi-center study aimed to analyze the outcomes of primary total knee arthroplasty using the Stemmable Tibia Attune system. A total of 100 patients who underwent primary total knee arthroplasty with Stemmable Tibia from January 2019 to December 2021 were enrolled in the study. Radiological outcomes (hip-knee-ankle axis and medial proximal tibial angle) were assessed preoperatively and postoperatively. Clinical outcomes (visual analog scale score, Hospital for Special Surgery score, Knee Society function score, Knee Society knee score, flexion contracture, further flexion, and range of motion) were analyzed preoperatively and at 6 weeks, 3 months, 6 months, 1 year, and 2 years postoperatively. Complications (periprosthetic joint infection and aseptic loosening) were examined. The hip-knee-ankle axis decreased (preoperative: 9.5° ± 6.3°, postoperative: 1.1° ± 2.7°), whereas the medial proximal tibial angle increased (preoperative: 84.6° ± 4.1°, postoperative: 89.8° ± 1.9°). The visual analog scale score, Hospital for Special Surgery score, Knee Society knee score, and Knee Society function score increased postoperatively. The Knee Society knee score indicated above good outcomes (100.0% and 99.0% at 1 and 2 years postoperatively, respectively). The Knee Society function score also showed above good results (98.0% and 93.0% at 1 and 2 years postoperatively, respectively). The range of motion significantly improved (p < 0.001): flexion contracture decreased from 9.10° ± 7.23° to 2.15° ± 2.87°, whereas further flexion increased from 136.05° ± 14.78° to 139.80° ± 10.02°. One patient developed periprosthetic joint infection; no early loosening was observed. In conclusion, Attune primary total knee arthroplasty with Stemmable Tibia not only is safe and effective but also leads to radiological and clinical improvements.

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BACKGROUND: Accurate estimation of implant size before surgery is crucial in preparing for total knee arthroplasty. However, this task is time-consuming and labor-intensive. To alleviate this burden on surgeons, we developed a reliable artificial intelligence (AI) model to predict implant size. METHODS: We enrolled 714 patients with knee osteoarthritis who underwent total knee arthroplasty from March 2010 to February 2014. All surgeries were performed by the same surgeon using implants from the same manufacturer. We collected 1412 knee anteroposterior (AP) and lateral view x-ray images and retrospectively investigated the implant size. We trained the AI model using both AP and lateral images without any clinical or demographic information and performed data augmentation to resolve issues of uneven distribution and insufficient data. Using data augmentation techniques, we generated 500 images for each size of the femur and tibia, which were then used to train the model. Using data augmentation techniques, we generated 500 images for each size of the femur and tibia, which were then used to train the model. We used ResNet-101 and optimized the model with the aim of minimizing the cross-entropy loss function using both the Stochastic Gradient Descent (SGD) and Adam optimizer. RESULTS: The SGD optimizer achieved the best performance in internal validation. The model showed micro F1-score 0.91 for femur and 0.87 for tibia. For predicting within ± one size, micro F1-score was 0.99 for femur and 0.98 for tibia. CONCLUSION: We developed a deep learning model with high predictive power for implant size using only simple x-ray images. This could help surgeons reduce the time and labor required for preoperative preparation in total knee arthroplasty. While similar studies have been conducted, our work is unique in its use of simple x-ray images without any other data, like demographic features, to achieve a model with strong predictive power.

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Model-based Roentgen Stereophotogrammetric Analysis (RSA) is able to measure the migration of metallic prostheses with submillimeter accuracy through contour-detection and 3D surface model matching techniques. However, contour-detection is only possible if the prosthesis is clearly visible in the radiograph; consequently Model-based RSA cannot be directly used for polymeric materials due to their limited X-ray attenuation; this is especially clinically relevant for all-polyethylene implants. In this study the radiopacity of unicompartmental Ultra-High Molecular Weight Polyethylene (UHMWPE) knee bearings was increased by diffusing an oil-based contrast agent into the surface to create three different levels of surface radiopacity. Model-based RSA was performed on the bearings alone, the bearings alongside a metallic component held in position using a phantom, the bearings cemented into a Sawbone tibia, and the bearings at different distances from the femoral component. For each condition the precision and accuracy of zero motion of Model-based RSA were assessed. The radiopaque bearings could be located in the stereo-radiographs using Model-based RSA an accuracy comparable to metallic parts for translational movements (0.03 mm to 0.50 mm). For rotational movements, the accuracy was lower (0.1∘ to 3.0∘). The measurement accuracy was compared for all the radiopacity levels and no significant difference was found (p=0.08). This study demonstrates that contrast enhanced radiopaque polyethylene can be used for Model-based RSA studies and has equivalent translational measurement precision to metallic parts in the superior-inferior direction.

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Total knee arthroplasty is a consistently successful, cost-efficient, and highly effective surgical procedure for treating severe knee osteoarthritis. The success and longevity of total knee arthroplasty depend significantly on the fixation method used to secure the prosthetic components. This comprehensive review examines the primary fixation methods (cemented, cementless, and hybrid fixation), analysing their biomechanics, clinical outcomes, advantages, and disadvantages, focusing on recent advances and trends in total knee arthroplasty fixation.

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Wear of the ultra-high molecular-weight polyethylene (UHMWPE) component in total knee arthroplasty contributes to implant failure. It is often detected late, when patients experience pain or instability. Early monitoring could enable timely intervention, preventing implant failure and joint degeneration. This study investigates the accuracy and precision (repeatability) of model-based wear measurement (MBWM), a novel technique that can estimate inlay thickness and wear radiographically. Six inlays were milled from non-crosslinked UHMWPE and imaged via X-ray in anteroposterior view at flexion angles 0°, 30°, and 60° on a phantom knee model. MBWM measurements were compared with reference values from a coordinate measurement machine. Three inlays were subjected to accelerated wear generation and similarly evaluated. MBWM estimated inlay thickness with medial and lateral accuracies of 0.13 ± 0.09 and 0.14 ± 0.09 mm, respectively, and linear wear with an accuracy of 0.07 ± 0.06 mm. Thickness measurements revealed significant lateral differences at 0° and 30° (0.22 ± 0.08 mm vs. 0.06 ± 0.06 mm, respectively; t-test, p = 0.0002). Precision was high, with average medial and lateral differences of - 0.01 ± 0.04 mm between double experiments. MBWM using plain radiographs presents a practical and promising approach for the clinical detection of implant wear.

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BACKGROUND: The use of a tibial stem for large deformities (> 10°) would reduce the incidence of pain. The aim of this study was to compare the effect of tibial stem on postoperative pain and aseptic loosening at the tibia in patients with a preoperative deformity > 10° in the frontal plane at 2 years follow-up. METHODS: This was a retrospective single-center case-control study. Ninety-eight patients with deformities greater than 10° in the frontal plane and a BMI > 30 kg/m2 who had undergone posterior-stabilized (PS) total knee arthroplasty (TKA) with a tibial stem were matched using a propensity score to 98 patients who had undergone PS TKA without a tibial stem. The primary endpoint was the pain rate at 2 years. The secondary endpoints were the rate of aseptic loosening of the tibia at 2 years post-operatively. RESULTS: A significant difference was found in the rate of postoperative pain at 2 years. It was higher in the group without tibial stem compared with the group with tibial stem (41.8% vs 17.3%, p = 0.0003). In the group without tibial stem, 24.4% of pain was mild, 61% moderate and no severe pain. In the tibial stem group, 47.1% of pain was mild, 41.2% moderate and no severe pain. A radiolucent line (RLL) was present at 2 years in 26.5% of prostheses in the without tibial stem group and in 9.2% of prostheses in the tibial stem group (p = 0.002). There was no difference between the two groups in terms of aseptic loosening. CONCLUSION: The use of a tibial stem in primary TKA in patients with frontal deformities greater than 10° reduces postoperative pain and the presence of radiolucent lines.

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OBJECTIVES: This study aimed to investigate the relationship between the severity of preoperative valgus deformity and clinical outcomes of neutrally aligned total knee arthroplasty (TKA). PATIENTS AND METHODS: A total of 376 knees with valgus deformity who underwent TKA from January 2006 to March 2014 were retrospectively screened, and 287 knees (242 patients; 32 males, 210 females; mean age: 64.5±8.8 years; range, 35 to 83 years) aligned neutrally after the operation were included. Patients were divided into four groups based on the preoperative hip-knee-ankle (HKA): mild (0°< HKA ≤5°, n=94), moderate (5°< HKA ≤10°, n=74), severe (10°< HKA ≤15°, n=75), and very severe (HKA >15°, n=44) groups. Range of motion (ROM), Knee Society Score (KSS), Visual Analog Scale (VAS) dynamic pain scores, and Forgotten Joint Score (FJS) were evaluated. Mechanical failures were recorded to assess prosthesis survival. A survival rate analysis was performed using Kaplan-Meier survival analysis. RESULTS: The degree of preoperative valgus deformity did not have a significant impact on the postoperative ROM, KSS, VAS dynamic pain scores, or FJS at the last follow-up. There were no significant differences in cumulative survival rates of neutrally aligned TKAs at 10 years between the four groups (p=0.513). CONCLUSION: The severity of preoperative valgus deformity did not affect the clinical outcomes of neutrally aligned TKAs in the minimum five-year follow-up. Additionally, it did not impact the survival rates of neutrally aligned TKAs over 10 years.

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Advanced 3D imaging and CT-based navigation have emerged as valuable tools to use in total knee arthroplasty (TKA), for both preoperative planning and the intraoperative execution of different philosophies of alignment. Preoperative planning using CT-based 3D imaging enables more accurate prediction of the size of components, enhancing surgical workflow and optimizing the precision of the positioning of components. Surgeons can assess alignment, osteophytes, and arthritic changes better. These scans provide improved insights into the patellofemoral joint and facilitate tibial sizing and the evaluation of implant-bone contact area in cementless TKA. Preoperative CT imaging is also required for the development of patient-specific instrumentation cutting guides, aiming to reduce intraoperative blood loss and improve the surgical technique in complex cases. Intraoperative CT-based navigation and haptic guidance facilitates precise execution of the preoperative plan, aiming for optimal positioning of the components and accurate alignment, as determined by the surgeon's philosophy. It also helps reduce iatrogenic injury to the periarticular soft-tissue structures with subsequent reduction in the local and systemic inflammatory response, enhancing early outcomes. Despite the increased costs and radiation exposure associated with CT-based navigation, these many benefits have facilitated the adoption of imaged based robotic surgery into routine practice. Further research on ultra-low-dose CT scans and exploration of the possible translation of the use of 3D imaging into improved clinical outcomes are required to justify its broader implementation.

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Aims: The optimal bearing surface design for medial unicompartmental knee arthroplasty (UKA) remains controversial. The aim of this study was to compare outcomes of fixed-bearing (FB) and mobile-bearing (MB) UKAs from a single high-volume institution. Methods: Prospectively collected data were reviewed for all primary cemented medial UKAs performed by seven surgeons from January 2006 to December 2022. A total of 2,999 UKAs were identified, including 2,315 FB and 684 MB cases. The primary outcome measure was implant survival. Secondary outcomes included 90-day and cumulative complications, reoperations, component revisions, conversion arthroplasties, range of motion, and patient-reported outcome measures. Overall mean age at surgery was 65.7 years (32.9 to 94.3), 53.1% (1,593/2,999) of UKAs were implanted in female patients, and demographics between groups were similar (p > 0.05). The mean follow-up for all UKAs was 3.7 years (0.0 to 15.6). Results: Using revision for any reason as an endpoint, five-year survival for FB UKAs was 97.2% (95% CI 96.4 to 98.1) compared to 96.0% for MB (95% CI 94.1 to 97.9; p = 0.008). The FB group experienced fewer component revisions (14/2,315, 0.6% vs 12/684, 1.8%; p < 0.001) and conversion arthroplasties (38/2315, 1.6% vs 24/684, 3.5%; p < 0.001). A greater number of MB UKAs underwent revision due to osteoarthritis progression (FB = 21/2,315, 0.9% vs MB = 16/684, 2.3%; p = 0.003). In the MB group, 12 (1.8%) subjects experienced bearing dislocations which required revision surgery. There were 15 early periprosthetic tibia fractures (0.6%) in the FB group compared to 0 for MB (p = 0.035). Conclusion: In similar patient populations, FB UKAs demonstrated slightly higher survival than a commonly used MB design. Adverse event profiles differed by bearing type, with an increased risk of bearing dislocation and OA progression with MB designs, and early periprosthetic tibia fractures for FB designs.

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BACKGROUND: Around 6,000 revision knee replacement procedures are performed in the United Kingdom each year. Three-quarters of procedures are for aseptic, elective reasons, such as progressive osteoarthritis, prosthesis loosening/wear, or instability. Our understanding of how we can best support these patients undergoing revision knee replacement procedures is limited. This study aimed to explore patients' experiences of having a problematic knee replacement and the impact of undergoing knee revision surgery for aseptic, elective reasons. METHODS: Qualitative semi structured interviews with 15 patients (8 women, 7 men; mean age 70 years: range 54-81) who had undergone revision knee surgery for a range of aseptic, elective indications in the last 12 months at an NHS Major Revision Knee Centre. Interviews were audio-recorded, transcribed, de-identified and analysed using reflexive thematic analysis. RESULTS: We developed six themes: Soldiering on; The challenge of navigating the health system; I am the expert in my own knee; Shift in what I expected from surgery; I am not the person I used to be; Lingering uncertainty. CONCLUSIONS: Living with a problematic knee replacement and undergoing knee revision surgery has significant impact on all aspects of patients' lives. Our findings highlight the need for patients with problematic knee replacements to be supported to access care and assessment, and for long-term psychological and rehabilitation support before and after revision surgery.

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Objective: To explore the clinical value of metagenomic next-generation sequencing (mNGS) in diagnosis and treatment of periprosthetic joint infection (PJI) after total knee arthroplasty (TKA). Methods: Between April 2020 and March 2023, 10 patients with PJI after TKA were admitted. There were 3 males and 7 females with an average age of 69.9 years (range, 44-83 years). Infection occurred after 8-35 months of TKA (mean, 19.5 months). The duration of infection ranged from 16 to 128 days (mean, 37 days). The preoperative erythrocyte sedimentation rate (ESR) was 15-85 mm/1 h (mean, 50.2 mm/1 h). The C reactive protein (CRP) was 4.4-410.0 mg/L (mean, 192.8 mg/L). The white blood cell counting was (3.4-23.8)×10 9/L (mean, 12.3×10 9/L). The absolute value of neutrophils was (1.1-22.5)×10 9/L (mean, 9.2×10 9/L). After admission, the joint fluid was extracted for bacterial culture method and mNGS test, and sensitive antibiotics were chosen according to the results of the test, and the infection was controlled in combination with surgery. Results: Seven cases (70%) were detected as positive by bacterial culture method, and 7 types of pathogenic bacteria were detected; the most common pathogenic bacterium was Streptococcus lactis arrestans. Ten cases (100%) were detected as positive by mNGS test, and 11 types of pathogenic bacteria were detected; the most common pathogenic bacterium was Propionibacterium acnes. The difference in the positive rate between the two methods was significant ( P=0.211). Three of the 7 patients who were positive for both the bacterial culture method and the mNGS test had the same results for the type of pathogenic bacteria, with a compliance rate of 42.86% (3/7). The testing time (from sample delivery to results) was (4.95±2.14) days for bacterial culture method and (1.60±0.52) days for mNGS test, and the difference was significant ( t=4.810, P<0.001). The corresponding sensitive antibiotic treatment was chosen according to the results of bacterial culture method and mNGS test. At 3 days after the one-stage operation, the CRP was 6.8-48.2 mg/L (mean, 23.6 mg/L); the ESR was 17-53 mm/1 h (mean, 35.5 mm/1 h); the white blood cell counting was (4.5-8.1)×10 9/L (mean, 6.1×10 9/L); the absolute value of neutrophils was (2.3-5.7)×10 9/L (mean, 4.1×10 9/L). All patients were followed up 12-39 months (mean, 23.5 months). One case had recurrence of infection at 6 months after operation, and the remaining 9 cases showed no signs of infection, with an infection control rate of 90%. Conclusion: Compared with bacterial culture method, mNGS test can more rapidly and accurately detect pathogenic bacteria for PJI after TKA, which is important for guiding antibiotics combined with surgical treatment of PJI.

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Objective: To conclude the research progress of unicompartmental knee arthroplasty (UKA) in the treatment of elderly patients with knee osteoarthritis (KOA). Methods: The literature on UKA at home and abroad in recent years was reviewed to summarize the clinical characteristics of elderly patients with KOA, perioperative management (including evaluating indications preoperatively, intraoperative prosthesis selection, postoperative complication management, etc). Results: Through reasonable preoperative evaluation, prosthesis selection, and advanced perioperative management, for elderly patients with KOA who meet the indications, UKA can be considered. Compared with total knee arthroplasty, the incidence of postoperative complications in elderly patients undergoing UKA is lower, joint awareness is reduced, functional improvement and satisfaction are higher. Meanwhile, choosing appropriate prostheses and fixation methods can lead to a good survival rate. Conclusion: UKA can provide a safe and effective treatment option for elderly patients with KOA within a certain range of indications.

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