Development of a multiplex Loop-Mediated Isothermal Amplification (LAMP) for the diagnosis of bacterial periprosthetic joint infection.

BACKGROUND: Periprosthetic joint infection (PJI) is one of the most serious and debilitating complications that can occur after total joint arthroplasty. Therefore, early diagnosis and appropriate treatment are important for a good prognosis. Recently, molecular diagnostic methods have been widely used to detect the causative microorganisms of PJI sensitively and rapidly. The Multiplex Loop-Mediated Isothermal Amplification (LAMP) method eliminates the complex temperature cycling and delays caused by temperature transitions seen in polymerase chain reaction (PCR) methods, making it faster and easier to perform compared to PCR-based assays. Therefore, this study developed a multiplex LAMP assay for diagnosing bacterial PJI using LAMP technology and evaluated its analytical and clinical performance. METHODS: We developed a multiplex LAMP assay for the detection of five bacteria: Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus agalactiae, Pseudomonas aeruginosa, and Escherichia coli, frequently observed to be the causative agents of PJI. The method of analytical sensitivity and cross-reactivity were determined by spiking standard strains into the joint synovial fluid. The analytical sensitivity of the multiplex LAMP assay was compared with that of a quantitative real-time PCR (qPCR) assay. Clinical performance was evaluated using 20 joint synovial fluid samples collected from patients suspected of having bacterial PJI. RESULTS: The analytical sensitivity of the gram-positive bacterial multiplex LAMP assay and qPCR were 105/104 CFU/mL, 103/103 CFU/mL, and 105/104 CFU/mL against S. agalactiae, S. epidermidis, and S. aureus, respectively. For P. aeruginosa and E. coli, the analytical sensitivity of the multiplex LAMP and qPCR assays were 105/104 and 106/104 CFU/mL, respectively. The multiplex LAMP assay detects target bacteria without cross-reacting with other bacteria, and exhibited 100% sensitivity and specificity in clinical performance evaluation. CONCLUSIONS: This multiplex LAMP assay can rapidly detect five high-prevalence bacterial species causing bacterial PJI, with excellent sensitivity and specificity, in less than 1 h, and it may be useful for the early diagnosis of PJI.

Clinical Outcomes and Complications of 2-Stage Septic Versus Aseptic Revision Total Knee Arthroplasty: A Systematic Review and Meta-Analysis.

BACKGROUND: Although several studies have compared the clinical outcomes of septic and aseptic revision total knee arthroplasty (TKA), their results have been controversial. Therefore, this study aimed to compare clinical outcomes and complications of septic and aseptic revision TKA through a systematic review and meta-analysis. METHODS: The PubMed (MEDLINE) and Embase databases were searched for studies evaluating the clinical outcomes and complications of 2-stage septic revision and aseptic revision TKAs. A systematic review of clinical outcomes (Knee Society Knee and Function Scores and range of motion) and complications (reoperation, infection, and failure rates) was conducted. RESULTS: Thirteen studies were included in the systematic review. The mean MINORS (Methodological Index for NOn-Randomized Studies) score of the included studies was 20.5 (range, 18 to 22). The meta-analysis revealed higher reoperation (risk ratio [RR], 1.98; 95% confidence interval [CI], 1.50 to 2.62; p < 0.00001), infection (RR, 4.08; 95% CI, 2.94 to 5.64; p < 0.00001), and failure rates (RR, 2.88; 95% CI, 1.38 to 6.03; p = 0.005) in septic revision TKAs than in aseptic revision TKAs. Moreover, septic revision TKAs showed lower Knee Society Knee Scores compared with aseptic TKAs (mean difference [MD], -6.86; 95% CI, -11.80 to -1.92; p = 0.006). However, the Knee Society Function Score (MD, -1.84; 95% CI, -7.84 to 3.80; p = 0.52) and range of motion (MD, -6.96°; 95% CI, -16.23° to 2.31°; p = 0.14) were not significantly different between septic and aseptic revision TKAs. CONCLUSIONS: Despite the heterogeneity of prosthesis designs and surgical protocols used in septic and aseptic revision TKAs, the results of this systematic review suggest that 2-stage septic revision TKAs have poorer clinical outcomes and higher complication rates than aseptic revision TKAs do. LEVEL OF EVIDENCE: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Safety and effectiveness of intra-articular injection of a highly cross-linked hyaluronic acid, LBSA0103 (Synovian): Results from a post-marketing surveillance study in South Korea.

This study aimed to assess the safety and effectiveness of the highly cross-linked hyaluronic acid-LBSA0103-in patients with knee osteoarthritis (OA) as per the prescribing information (PI) in South Korea. A total of 3,140 subjects aged ≥19 years were enrolled in this post-marketing surveillance (PMS) study from 2013 to 2019. The subjects received one or two injections of LBSA0103. The median duration of follow-up was 308 days. Adverse events (AEs), adverse drug reactions (ADRs), and serious AEs (SAEs) were monitored. Effectiveness was evaluated based on an index of effectiveness in accordance with the guidelines established by the Ministry of Food and Drug Safety and using a 100-mm visual analog scale (VAS) for weight-bearing pain. Overall, 250 subjects (7.96%) experienced 292 AEs and of these, unexpected AEs occurred in 114 subjects (3.63% [95% CI: 3.00-4.35]). Injection site pain was the most frequent AE reported by 81 subjects (2.58% [95% confidence intervals (CI): 2.05-3.20]). One hundred subjects experienced 108 ADRs (3.18% [95% CI: 2.60, 3.86]) and 15 unexpected ADRs were experienced by 13 subjects (0.41% [95% CI: 0.22-0.71]). Seventeen subjects experienced 22 SAEs (0.54% [95% CI: 0.32-0.87]) during the entire PMS period, and all were considered "unlikely" related to the study drug. Most AEs were mild in terms of severity and resolved during the study period. LBSA0103 was also effective in relieving symptomatic pain in knee OA patients. The condition in more than 80% of the subjects was considered to be improved when assessed by the investigators. LBSA0103 resulted in a significant reduction in the mean VAS score at 12 weeks after the first and second injections (24.79 (± 20.55) mm and 17.63 (±12.31) mm, respectively; p<0.0001). In conclusion, LBSA0103, used for the treatment of knee OA in a real-world setting, was well tolerated, with an acceptable safety profile and consistent therapeutic effect.

Arthroscopic cystectomy for Baker's cysts with and without one-way valve lesions: incidence of one-way valve lesion, associated pathologies, and clinical outcomes.

INTRODUCTION: A one-way valve lesion plays an important role in the formation of Baker's cysts and serves as an important landmark for accessing these cysts during arthroscopic surgery. This study aimed to investigate the incidence of one-way valve lesions and their effect on clinical outcomes in patients who underwent arthroscopic cystectomy for Baker's cysts. MATERIALS AND METHODS: Patients who underwent arthroscopic cystectomy for Baker's cysts between June 2005 and November 2017 were retrospectively reviewed. Patient demographic characteristics, radiologic/arthroscopic findings (presence of one-way valve lesions, concurrent chondral and meniscal lesions, and cyst wall thickness), and clinical outcomes (clinical recurrence rate, Lysholm score, and complications) at the 2-year follow-up were evaluated. Subgroup analysis was performed to compare clinical outcomes between patients with and without one-way valve lesions. RESULTS: Thirty patients (mean age, 57.4 ± 9.4 years) were included in this study. One-way valve lesions were surgically documented in 11 patients (36.7%). Ten patients (33.3%) had chondral lesions with an International Cartilage Repair Society grade ≥ 3, and 23 patients (76.7%) had concurrent chondral and meniscal lesions. At the 2-year follow-up, none of the patients had experienced clinical recurrence; the mean Lysholm score was 76.3 ± 17.5 (48-100). Three patients reported persistent pain, while two reported numbness or paresthesia. Subgroup analysis showed no significant differences in clinical recurrence rates, Lysholm scores, and complication rates between the groups. CONCLUSIONS: The incidence of one-way valve lesions during arthroscopic cystectomy for Baker's cysts was lower than that previously reported. Arthroscopic cystectomy showed good clinical results in patients with and without these lesions.

The Tibial Tuberosity-Rotational Angle as a Novel Predisposing Parameter for Patellar Dislocation.

Background: The tibial tuberosity (TT) in the axial plane is located on a curved line along the anterior cortex of the proximal tibia. Therefore, the linear measurement of TT position may not fully reflect TT malposition. Purpose: To introduce TT-rotational angle (TT-RA) as a new anatomical parameter, which means the rotation of the TT relative to the dorsal condylar line of the tibia, and to validate its predictive value for patellar dislocation. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Included were 46 patients with a history of patellar dislocation and 46 age- and sex-matched controls who underwent axial magnetic resonance imaging. Seven radiological parameters were measured and compared between the 2 groups, including TT-trochlear groove (TT-TG) distance, tibial tubercle-posterior cruciate ligament (TT-PCL) distance, TT-PCL ratio, TT lateralization (TTL), trochlear groove medialization (TGM), TT-RA, trochlear groove-posterior condylar axis angle (TG-PCA), and knee rotation. The predictive values of parameters for patellar dislocation were assessed using multiple logistic regression analysis. Results: The intra- and interobserver correlation coefficients for measuring the radiographic parameters showed good to excellent values., respectively. There were significant differences in the TT-TG distance (13.9 vs 6.8 mm; P < .001), TT-RA (16.0° vs 9.1°; P < .001), TG-PCA (93.7° vs 95.4°; P = .017), and knee rotation (0.9° vs 5.3°; P < .001) between the 2 groups. However, there was no significant difference in TT-PCL distance (20.7 vs 19.4 mm; P = .075), TT-PCL ratio (28.0% vs 26.6%; P = .136), TTL (65.7% vs 64.9%; P = .270), or TGM (54.9% vs 55.0%; P = .923). Multivariable analysis showed that 3 parameters were significantly associated with patellar dislocation: TT-RA (OR, 1.57; P < .001), TT-TG distance (OR, 1.52; P = .002), and knee rotation (OR, 0.75; P = .022). Conclusion: The TT-RA was a reliable predisposing parameter of patellar instability. It can be an alternative method of measurement when the TT-TG distance is not clearly defined.

Predictive Factors for Lateral Hinge Fracture in Medial Closing Wedge Distal Femoral Osteotomy.

BACKGROUND: Recent studies have reported that lateral hinge fracture (LHF) has a negative effect on bone healing at the osteotomy site after medial closing wedge distal femoral osteotomy (MCDFO). However, limited evidence exists in the literature regarding the predictive factors for LHF in MCDFO. HYPOTHESIS: A large medial closing gap and a lateral hinge position in the supracondylar area would increase plain radiography-based and/or computed tomography (CT)-based LHF in MCDFO. STUDY DESIGN: Case control study; Level of evidence, 3. METHODS: We retrospectively evaluated 67 knees of 53 patients (mean age, 37.4 ± 16.9 years) who underwent MCDFO between May 2009 and June 2021. The surgical indications for MCDFO were genu valgum deformity combined with either lateral compartment osteoarthritis or recurrent patellar dislocation. The presence of LHF was evaluated based on immediate postoperative plain radiography and CT scans. The predictive factors for LHF in MCDFO were investigated using multivariate logistic regression analysis. RESULTS: LHFs were identified in 21 knees (31.3%) through plain radiography and in 40 knees (59.7%) through CT. Multivariate logistic regression analysis showed that the medial closing gap and lateral hinge position were predictive factors for plain radiography- and CT-based LHF after MCDFO. Controlling for other variables, we found that an increase in the medial opening gap by 1 mm increased the likelihood of plain radiography-based LHF by a factor of 1.805 (95% CI, 1.291-2.525; P = .001) and CT-based LHF by 1.333 (95% CI, 1.003-1.772; P = .048). Moreover, a lateral hinge position in the supracondylar area increased the likelihood of plain radiography-based LHF by a factor of 9.870 (95% CI, 2.179-44.720; P = .003) and CT-based LHF by 5.686 (95% CI, 1.124-28.754; P = .036). CONCLUSION: A large medial closing gap and lateral hinge position in the supracondylar area are associated with LHF in MCDFO. Care should be taken to prevent LHF in MCDFO with a large medial closing gap. Moreover, a lateral hinge position in the supracondylar area should be avoided to decrease the incidence of LHF in MCDFO.

Feasibility of Loop-Mediated Isothermal Amplification for Rapid Detection of Methicillin-Susceptible and Methicillin-Resistant Staphylococcus aureus in Tissue Samples.

Background: To date, few studies have investigated the feasibility of the loop-mediated isothermal amplification (LAMP) assay for identifying pathogens in tissue samples. This study aimed to investigate the feasibility of LAMP for the rapid detection of methicillin-susceptible or methicillin-resistant Staphylococcus aureus (MSSA or MRSA) in tissue samples, using a bead-beating DNA extraction method. Methods: Twenty tissue samples infected with either MSSA (n = 10) or MRSA (n = 10) were obtained from patients who underwent orthopedic surgery for suspected musculoskeletal infection between December 2019 and September 2020. DNA was extracted from the infected tissue samples using the bead-beating method. A multiplex LAMP assay was conducted to identify MSSA and MRSA infections. To recognize the Staphylococcus genus, S. aureus, and methicillin resistance, 3 sets of 6 primers for the 16S ribosomal ribonucleic acid (rRNA) and the femA and mecA genes were used, respectively. The limit of detection and sensitivity (detection rate) of the LAMP assay for diagnosing MSSA and MRSA infection were analyzed. Results: The LAMP result was positive for samples containing 103 colony-forming unit (CFU)/mL for 16S rRNA, 104 CFU/mL for femA, and 105 CFU/mL for mecA. The limits of detection for 16S rRNA and femA were not different between MSSA and MRSA. For the 10 MSSA-positive samples, the LAMP assay showed 100% positive reactions for 16S rRNA and femA and a 100% negative reaction for mecA. For the 10 MRSA-positive samples, the LAMP assay showed 100% positive reactions for 16S rRNA and mecA but only 90% positive reactions for femA. The sensitivity (detection rate) of the LAMP assay for identifying MSSA and MRSA in infected tissue samples was 100% and 90%, respectively. Conclusions: The results of this study suggest that the LAMP assay performed with tissue DNA samples can be a useful diagnostic method for the rapid detection of musculoskeletal infections caused by MSSA and MRSA.

Adjustable-Loop Cortical Suspensory Fixation Results in Greater Tibial Tunnel Widening Compared to Interference Screw Fixation in Primary Anterior Cruciate Ligament Reconstruction.

Background: Although the use of adjustable-loop suspensory fixation has increased in recent years, the influence of the shortcomings of suspensory fixation, such as the bungee-cord or windshield-wiper effects, on tunnel widening remains to be clarified. Hypothesis/Purpose: The purpose of this study was to compare adjustable-loop femoral cortical suspensory fixation and interference screw fixation in terms of tunnel widening and clinical outcomes after anterior cruciate ligament reconstruction (ACLR). We hypothesized that tunnel widening in the adjustable-loop femoral cortical suspensory fixation (AL) group would be comparable to that in the interference screw fixation (IF) group. Methods: This study evaluated patients who underwent primary ACLR at our institution between March 2015 and June 2019. The femoral and tibial tunnel diameters were measured using plain radiographs in the immediate postoperative period and 2 years after ACLR. Tunnel widening and clinical outcomes (Lysholm score, 2000 International Knee Documentation Committee subjective score, and Tegner activity level) were compared between the two groups. Results: There were 48 patients (mean age, 29.8 ± 12.0 years) in the AL group and 44 patients (mean age, 26.0 ± 9.5 years) in the IF group. Tunnel widening was significantly greater in the AL group than that in the IF group at the tibia anteroposterior (AP) middle (2.03 mm vs. 1.32 mm, p = 0.017), tibia AP distal (1.52 mm vs. 0.84 mm, p = 0.012), tibia lateral proximal (1.85 mm vs. 1.00 mm, p = 0.001), tibia lateral middle (2.36 mm vs. 1.03 mm, p < 0.001), and tibia lateral distal (2.34 mm vs. 0.85 mm, p < 0.001) levels. There were no significant differences between the two groups with respect to femoral tunnel widening and clinical outcomes. Conclusions: Tibial tunnel widening was significantly greater in the AL group than in the IF group at 2 years after primary ACLR. However, the clinical outcomes in the two groups were comparable at 2 years.

Determining the Substantial Clinical Benefit Values for Patient-Reported Outcome Scores After Primary ACL Reconstruction.

Background: Little is known about the threshold of patient-reported outcomes (PROs) at which patients perceive to have attained a substantial clinical benefit (SCB) after anterior cruciate ligament reconstruction (ACLR). Purpose: To determine the SCB value of PROs 1 year after ACLR in the general population and to determine factors that predict SCB attainment. Study Design: Case series; Level of evidence, 4. Methods: The Lysholm, International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC-SKF), Tegner, and Anterior Cruciate Ligament-Return to Sport after Injury (ACL-RSI) scores were examined postoperatively in 88 patients who underwent ACLR. At the 12-month follow-up visit, the patients answered 2 independent anchor questions about daily discomfort and functional recovery. Receiver operating characteristic (ROC) curve analysis was used to differentiate PRO scores between patients who responded as having no difficulty versus some difficulty with daily knee discomfort (anchor question 1) and between patients with substantial recovery versus nonsubstantial recovery of knee function (anchor question 2). The area under the ROC curve (AUC) was calculated to assess reliability, and the differences between the AUC values were compared. Multivariate logistic regression analyses were performed to determine predictors affecting SCB attainment. Results: There were 76 patients enrolled in this study. The 12-month Lysholm, IKDC-SKF, Tegner, and ACL-RSI scores that corresponded to the SCB were 88.0, 85.1, 6.5, and 64.2 for anchor question 1 and 84.5, 77.7, 5.5, and 57.1 for anchor question 2, respectively. The AUC values obtained from the ROC curve analyses showed acceptable to excellent reliability (anchor question 1: Lysholm, 0.90; IKDC-SKF, 0.86; Tegner, 0.71; ACL-RSI, 0.92; anchor question 2: Lysholm, 0.80; IKDC-SKF, 0.90; Tegner, 0.82; ACL-RSI, 0.82) and were all statistically significant (P < .001 to P = .028). For all PROs, younger age (Odds Ratio (OR), 0.88-0.94; P < .001 to P = .027) and greater muscle strength (OR, 1.03-1.07; P < .001 to P = .023) were predictive factors of SCB attainment. Conclusion: The postoperative Lysholm, IKDC-SKF, Tegner, and ACL-RSI scores showed acceptable to excellent reliability in predicting the SCB after ACLR in the general population. Age at surgery and thigh muscle strength influenced SCB attainment for all PROs.

Femoral matched tibia component rotation has little effect on the tibial torsion after total knee arthroplasty.

PURPOSE: Tibiofemoral synchronization technique matches the rotational alignment of the tibial component to the femoral component during the total knee arthroplasty (TKA). The rotational axis of the proximal tibia can be changed by this technique, which affects tibial torsion postoperatively. The purpose of this study was to investigate whether the tibiofemoral synchronization technique affect the tibial torsion, and the lower limb rotation after primary TKA. It was hypothesised that the tibial torsion would change after primary TKA. METHODS: Ninety-three posterior stabilised TKAs from 89 patients were included from January 2017 to December 2018. Mechanical hip-knee-ankle axis (mHKA), in plain radiographs, femoral anteversion, tibial torsion, femoral neck-malleolar angle (FNMA), and rotational alignment of the femoral and the tibial components in pre- and postoperative CT scans were measured by two blinded observers. The primary outcome was a postoperative change in femoral anteversion, tibial torsion and FNMA. Clinical outcomes were evaluated using the American Knee Society Knee Score (AKSKS)/Function Score (AKSFS), and Oxford Knee Score (OKS) preoperatively and at 1 year after TKA. Patients' perception of changes in the foot progression angle after TKA was investigated. Statistical significance was set at p < 0.05. RESULTS: The mean rotational mismatch between the femoral and the tibial component was 0.6 ± 3.2°. There was a significant decrease in femoral anteversion (9.5 ± 6.7° vs. 5.2 ± 6.6°, p < 0.001), and a significant increase in the FNMA (17.6 ± 9.7° vs. 21.8 ± 10.5°, p = 0.005) after TKA, while no significant change in tibia torsion was observed (25.4 ± 8.8° vs. 24.9 ± 9.3°, p = 0.739). AKSS (37.8 ± 15.1 vs. 92.8 ± 8.8, p < 0.001), AKSFS (53.9 ± 18.1 vs. 89.9 ± 5.3, p < 0.001), and OKS (18.0 ± 7.3 vs. 39.9 ± 4.8, p < 0.001) were significantly improved at 1 year after TKA. Ten knees (11%) had changes in tibial torsion greater than ± 10° postoperatively. Four of five patients who had changes in FNMA greater than 15° perceived the external rotation of the foot progression angle after TKA. All four patients had an increase in tibial torsion larger than 10°. CONCLUSION: Our study shows that the tibiofemoral synchronization technique less likely affects the tibial torsion after primary TKA.

Intra-Articular Injection of a Novel DVS Cross-Linked Hyaluronic Acid Manufactured by Biological Fermentation (YYD302) in Patients With Knee Osteoarthritis: A Double-Blind, Randomized, Multicenter, Noninferiority Study.

PURPOSE: This double-blind, randomized, Phase III clinical trial was conducted to assess the efficacy and safety of the novel divinyl sulfone cross-linked hyaluronate (YYD302) compared with the 1,4-butanediol diglycidyl ether cross-linked hyaluronate (Synovian) in patients with knee osteoarthritis. METHODS: A total of 184 patients with osteoarthritis (Kellgren-Lawrence grade I-III) were randomized to 1 of 2 study groups (YYD302 group, n = 95; Synovian group, n = 89). A single injection of YYD302 or Synovian was given to both groups, and 182 participants completed the study (YYD302 group, n = 95; Synovian group, n = 87). The primary end point was the change in weight-bearing pain (WBP) at 12 weeks after the primary single injection. Secondary end points included the Knee Injury and Osteoarthritis Outcome Score; the Western Ontario and McMaster Universities Osteoarthritis Index score; the Patient Global Assessment and Investigator Global Assessment; the range of motion, swelling, and tenderness of the target knee; OMERACT-OARSI responder rate; WBP responder rate (the proportion of patients achieving at least 20 mm or 40% decrease in WBP); and rate of rescue medicine use and its total consumption at weeks 2, 4, and 12. Based on the efficacy results at week 12, the responders were administered an additional single injection of the same study drug at week 24, and safety and efficacy were additionally assessed at week 36. FINDINGS: Mean changes of WBP at 12 weeks after the primary injection were -31.76 mm with YYD302 and -29.74 mm with Synovian, proving noninferiority of the YYD302 group to the Synovian group as the lower bound of the 95% CI (-4.3 to 8.3) was well above the predefined margin (-10 mm). At week 2, the Knee Injury and Osteoarthritis Outcome Score (total, pain, activities of daily living, and sports/recreation) and Western Ontario and McMaster Universities Osteoarthritis Index scores (total, stiffness) were significantly better in the YYD302 group than in the Synovian group. There were no significant differences between the groups in all other end points. Local overall adverse events (pain, heat, erythema, or swelling) at the injection site were observed in 48.4% of the YYD302 group and in 47.7% of the Synovian group. No serious reactions were reported. There was no statistically significant difference between the 2 groups regarding re-injected patients (YYD302 group, n = 54; Synovian group, n = 46) in any of the efficacy outcomes at week 36. IMPLICATIONS: The results of this study support that YYD302 is comparable to Synovian in terms of the efficacy and safety of the intra-articular injection treatment for osteoarthritis of the knee joint. Furthermore, YYD302 provided faster improvements in some efficacy assessments compared with Synovian. ClinicalTrials.gov identifier: NCT03561779.

Mesenchymal stem cells for enhancing biological healing after meniscal injuries.

The meniscus is a semilunar fibrocartilage structure that plays important roles in maintaining normal knee biomechanics and function. The roles of the meniscus, including load distribution, force transmission, shock absorption, joint stability, lubrication, and proprioception, have been well established. Injury to the meniscus can disrupt overall joint stability and cause various symptoms including pain, swelling, giving-way, and locking. Unless treated properly, it can lead to early degeneration of the knee joint. Because meniscal injuries remain a significant challenge due to its low intrinsic healing potential, most notably in avascular and aneural inner two-thirds of the area, more efficient repair methods are needed. Mesenchymal stem cells (MSCs) have been investigated for their therapeutic potential in vitro and in vivo. Thus far, the application of MSCs, including bone marrow-derived, synovium-derived, and adipose-derived MSCs, has shown promising results in preclinical studies in different animal models. These preclinical studies could be categorized into intra-articular injection and tissue-engineered construct application according to delivery method. Despite promising results in preclinical studies, there is still a lack of clinical evidence. This review describes the basic knowledge, current treatment, and recent studies regarding the application of MSCs in treating meniscal injuries. Future directions for MSC-based approaches to enhance meniscal healing are suggested.

Detection of Lateral Hinge Fractures After Medial Closing Wedge Distal Femoral Osteotomy: Computed Tomography Versus Plain Radiography.

BACKGROUND: Limited evidence exists in the literature regarding the detection rates of lateral hinge fracture (LHF) on computed tomography (CT) after medial closing wedge distal femoral osteotomy (MCDFO). Moreover, the effect of LHF on bone healing after MCDFO remains unclear. HYPOTHESIS: The detection rates of LHF after MCDFO would be higher on CT than on plain radiography. The incidence of problematic bone healing would be higher in the knees with LHF than in those without LHF. STUDY DESIGN: Cohort study (diagnosis), Level of evidence, 3. METHODS: Patients who underwent MCDFO between May 2009 and July 2019 were retrospectively evaluated. The presence of LHF was evaluated using immediate postoperative plain radiography and CT. The detection rates of LHF on plain radiography and CT were compared. The incidence of problematic bone healing (nonunion, delayed union, and loss of correction) was also compared between the knees with LHF and those without LHF. RESULTS: A total of 55 knees of 43 patients (mean age, 37.7 ± 16.7 years) were included in the study. Although 33 LHFs were detected on CT, only 19 LHFs were detected on plain radiography. The detection rate of LHF was significantly higher on CT than on plain radiography (60% vs 34.5%; P = .008). At 1-year follow-up, 10 cases of problematic bone healing (1 nonunion, 4 delayed unions, and 5 losses of correction) were identified. The incidence of problematic bone healing was significantly higher in the knees with LHF than in those without LHF as shown on plain radiography (36.8% vs 8.3%; P = .001) and CT (30.3% vs 0%; P = .004). CONCLUSION: LHF can be detected better on CT than on plain radiography and has a negative effect on bone healing after MCDFO. For patients with LHF detected on either plain radiography or CT, careful rehabilitation with close follow-up is recommended.

Arthroscopy-controlled medial reefing and lateral release for recurrent patellar dislocation: clinical, radiologic outcomes and complications.

BACKGROUND: Few studies have reported the clinical outcomes of the medial reefing procedure and lateral release with arthroscopic control of medial retinacular tension in patients with recurrent patellar dislocation. The purpose of this study was to investigate the clinical, radiologic outcomes and complications of arthroscopy-controlled medial reefing and lateral release. METHODS: Patients who underwent arthroscopy-controlled medial reefing and lateral release for recurrent patellar dislocation between November 2007 and June 2017 were retrospectively evaluated. The clinical outcome (Kujala score), radiologic outcome (congruence and patellar tilt angles), and complications were evaluated at final follow-up. The results were also compared with literature-reported outcomes of other surgical procedures for patellar dislocation. RESULTS: Twenty-five patients (mean age, 18.3 ± 4.8 years) were included in the study. The mean clinical follow-up period was 7.0 ± 2.5 (range, 3.8-12.2) years. The mean Kujala score was significantly improved from 54.7 ± 14.0 (range, 37-86) preoperatively to 91.0 ± 7.6 (range, 63-99) at a mean follow-up period of 7 years (P < 0.001). The radiologic results also significantly improved from 17.8° ± 5.9° to 6.8° ± 2.4° (P < 0.001) in the congruence angle and from 17.5° ± 8.2° to 5.6° ± 3.1° (P < 0.001) in the patella tilt angle at a mean follow-up period of 3.6 years. One patient developed a redislocation after a traumatic event, and two patients showed patellofemoral osteoarthritis progression. CONCLUSIONS: Arthroscopy-controlled medial reefing and lateral release significantly improved the clinical and radiologic outcomes of the patients with recurrent patellar dislocation at a mean follow-up period of 7 years. The results of this study are comparable with the literature-reported outcomes of other surgical procedures for patellar dislocation. LEVEL OF EVIDENCE: Level IV, retrospective therapeutic case series.

Low Rate of Return to Preinjury Tegner Activity Level Among Recreational Athletes: Results at 1 Year After Primary ACL Reconstruction.

BACKGROUND: There is limited information about the functional recovery and rate of return to preinjury levels of sports among recreational athletes after anterior cruciate ligament reconstruction (ACLR). PURPOSE: To investigate the recovery of quadriceps or hamstring strength, assess functional performance, and determine the rate of return to preinjury sports levels among recreational athletes at 1 year after ACLR. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 91 recreational-level athletes who underwent anatomic single-bundle ACLR were enrolled. We evaluated the limb symmetry index (LSI) of the quadriceps and hamstring peak torque strength at 60°, in addition to hop test performance (single-leg, triple, crossover, and 6-m timed), patient-reported outcomes, and pre- versus postoperative Tegner activity levels. Outcomes were compared between younger (age <25 years) and older patients (age ≥25 years). RESULTS: There were 48 patients in the younger group and 43 patients in the older group. At 1-year follow-up, the overall LSIs for quadriceps strength and hamstring strength were 77% and 86%, respectively, and the LSIs of the hop tests were 79% for single-leg, 81% for triple, 84% for crossover, and 85% for 6-m timed hop. Overall, only 24% patients returned to their preinjury Tegner level, and only 8% of patients met the criteria for return to pivoting, cutting, and jumping sports. At 1-year follow-up, the younger group showed significantly more quadriceps strength than the older group (85% vs 64%; P = .0001), better single, triple, crossover, and 6-m timed hop test results (85% vs 69%, P = .003; 84% vs 75%, P = .046; 91% vs. 74%, P < .001; and 91% vs 76%, P = .003, respectively), higher Lysholm score (87 vs 74; P < 0.001) and International Knee Document Committee score (82 vs 66; P < .001), and a higher rate of return to preinjury Tegner level (35% vs 12%; P = .009). CONCLUSION: Only 24% of patients returned to the preinjury Tegner level at 1 year after ACLR (35% younger group vs 12% older group; P = .009). This information might be helpful in setting realistic expectations for recreational athletes after surgery.

Intra-articular Administration of Tranexamic Acid Has No Effect in Reducing Intra-articular Hemarthrosis and Postoperative Pain After Primary ACL Reconstruction Using a Quadruple Hamstring Graft: A Randomized Controlled Trial.

BACKGROUND: Insufficient data are available to support the routine use of tranexamic acid (TXA) in anterior cruciate ligament (ACL) surgeries with respect to administration method and frequency, exposure duration, dose, and adverse effects. PURPOSE: To investigate whether intra-articular (IA) administration of TXA could reduce hemarthrosis and postoperative pain in patients after ACL reconstruction. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: A total of 47 patients were included in this study, which was performed between July 2017 and May 2019. Single-bundle reconstructions using autologous hamstring tendon grafts were performed in all patients. The patients were randomized into 2 groups: the TXA group (received the index procedure with 100-mL IA injection of TXA [30 mg/mL]) and a control group (did not receive IA injection of TXA). No patients received a drain. Blood loss was calculated on the basis of hemoglobin balance at postoperative day (PD) 2. The visual analog scale (VAS) for pain score was assessed at PD 3. The midpatellar circumference was measured at PD 2 and PD 5. Knee range of motion (ROM) was evaluated 6 weeks after surgery. RESULTS: The mean ± SD blood loss was 467 ± 242 mL in the TXA group and 558 ± 236 mL in the control group. No significant differences were found for blood loss (P = .20), VAS pain scores (P = .28), ROM at postoperative week 6 (P = .61), or patellar circumference at PD 2 (P = .75) and PD 5 (P = .84). CONCLUSION: This study showed that IA administration of 3.0 g of TXA had no effect in reducing blood loss and postoperative pain after primary anatomic single-bundle ACL reconstruction using quadruple hamstring autografts. REGISTRATION: NCT04042688 (ClinicalTrials.gov identifier).

Densely Distilled Flow-Based Knowledge Transfer in Teacher-Student Framework for Image Classification.

We propose a new teacherstudent framework (TSF)-based knowledge transfer method, in which knowledge in the form of dense flow across layers is distilled from a pre-trained "teacher" deep neural network (DNN) and transferred to another "student" DNN. In the case of distilled knowledge, multiple overlapped flow-based items of information from the pre-trained teacher DNN are densely extracted across layers. Transference of the densely extracted teacher information is then achieved in the TSF using repetitive sequential training from bottom to top between the teacher and student DNN models. In other words, to efficiently transmit extracted useful teacher information to the student DNN, we perform bottom-up step-by-step transfer of densely distilled knowledge. The performance of the proposed method in terms of image classification accuracy and fast optimization is compared with those of existing TSF-based knowledge transfer methods for application to reliable image datasets, including CIFAR-10, CIFAR-100, MNIST, and SVHN. When the dense flow-based sequential knowledge transfer scheme is employed in the TSF, the trained student ResNet more accurately reflects the rich information of the pre-trained teacher ResNet and exhibits superior accuracy to the existing TSF-based knowledge transfer methods for all benchmark datasets considered in this study.

Epidemiology of Bearing Dislocations After Mobile-Bearing Unicompartmental Knee Arthroplasty: Multicenter Analysis of 67 Bearing Dislocations.

BACKGROUND: This study investigated the epidemiology and causes of bearing dislocations following mobile-bearing unicompartmental knee arthroplasty (MUKA) and determined whether the incidence of primary bearing dislocations decreases as surgeon experience increases. METHODS: We retrospectively reviewed the bearing dislocations following MUKAs performed by 14 surgeons with variable experience levels. Causes of bearing dislocations were determined based on the surgical records, radiographs, and operator's suggestion. Using a chi-squared test, the incidence of bearing dislocation was compared between the first 50, the second 50, and the next 100 unicompartmental knee arthroplasties (UKAs) of each surgeon's cohort. RESULTS: There were 67 (3.6%) bearing dislocations from 1853 MUKAs. The mean time to bearing dislocations after index MUKAs was 33 months (range, 1-144 months); 55% of the bearing dislocations occurred within 2 years after the index MUKAs. Primary bearing dislocations (n = 58) were the most common, followed by secondary (n = 6) and traumatic dislocations (n = 3). There was no significant difference in the incidence of bearing dislocation between the first 50 and second 50 UKAs for each surgeon. Two surgeons showed a significant decrease in bearing dislocations in their second 100 UKAs, while the other surgeons did not show a difference between their first 100 and second 100 UKAs. CONCLUSION: Most bearing dislocations after MUKAs were related to technical errors such as component malposition or gap imbalance. This study did not confirm that the incidence of bearing dislocations decreases as the number of cases increases. LEVEL OF EVIDENCE: IV, Case series.

Serum uric acid in asymptomatic adults is weakly associated with carotid artery FDG uptake but not intima-media thickness.

BACKGROUND: This study investigated the association of serum uric acid (UA) with carotid fluoro-2-deoxyglucose (FDG) uptake as a marker of inflammatory atherosclerosis. METHODS AND RESULTS: In this cross-sectional retrospective study of 970 otherwise healthy adults, subjects in the greater serum UA quartiles had higher triglyceride (P < .001), lower high-density lipoprotein cholesterol (P < .05), and lower estimated GFR (P < .001). Mean and maximum Target-to-background ratios (TBRs) of carotid FDG uptake measured by positron emission tomography were significantly increased across greater serum UA quartiles (1.35 and 1.57 for Q1, 1.38 and 1.60 for Q2, 1.39 and 1.62 for Q3, and 1.39 and 1.61 for Q4; P = .001 and < .001). Carotid intima-media thickness was not different. Serum UA showed weak but significant correlations with estimated GFR (P < .001), and with mean (P < .001) and maximum carotid TBR (P = .004). Serum UA correlated with mean TBR in male (P = .008) and female subjects (P = .011), in high (≥ 70; P = .015) and low estimated GFR (< 70; P = .035), and in normotensive (P = .001) but not in hypertensive subjects. CONCLUSIONS: Elevated serum UA in asymptomatic adults is associated with increased carotid FDG uptake, which suggests a potential role of UA in carotid inflammatory atherosclerosis.

Korean Version of the Anterior Cruciate Ligament-Return to Sport after Injury Scale: Translation and Cross-cultural Adaptation.

BACKGROUND: To translate into Korean and culturally adapt the anterior cruciate ligament-return to sports after injury (ACL-RSI) scale assessing psychological readiness to return to sports after ACL reconstruction and to validate its psychometric properties. METHODS: The ACL-RSI scale was forward translated into Korean and back-translated into English for cultural adaptation according to the standardized guideline. For validation, the Korean version of the ACL-RSI (ACL-RSI Kr) was administered to patients who underwent ACL reconstruction. The following subjective questionnaires were also administered: International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC-SKF), Lysholm scale, Knee injury and Osteoarthritis Outcome Score (KOOS), and a Return to Sports Questionnaire. Test-retest reliability, internal consistency, content validity, construct validity, and discriminant validity of the ACL-RSI Kr were assessed. RESULTS: A total of 129 patients (102 men and 27 women) were included in the study. Their mean age was 28.3 years. The average follow-up duration was 13.2 months. Test-retest reliability was remarkable (intraclass correlation coefficient, 0.949), internal consistency was high (Cronbach's alpha, 0.932), and floor and ceiling effects were confirmed to be less than 10%. Construct validity assessed by correlation analysis with KOOS, IKDC-SKF, and Lysholm scale showed the correlation coefficients ranging from 0.169 to 0.679 (all p < 0.01). Compared with the Return to Sports Questionnaire, statistically significant difference was found in the ACL-RSI Kr between patients who received more than 7 points and less than 7 points (72.2 vs. 60.3, p = 0.025) for performance level scored using a 10-point Likert scale, proving its discriminative value. CONCLUSIONS: The ACL-RSI Kr demonstrated good psychometric properties. This scale can be an excellent instrument for evaluating patient's psychological readiness to return to sports after ACL injury.