Female sample screening using colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) targeting non-coding RNA XIST.

Forensic sample screening is important for establishing an effective DNA typing workflow. The detection of sex-specific markers in forensic samples highlights the necessity for further analysis. Y-chromosome DNA can confirm male contributions, but female contributions are difficult to confirm using DNA-based methods. To address this, we developed a colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay targeting the long non-coding RNA X-inactive specific transcript (XIST) to screen female samples. Operating at 65 °C for 30 min, the assay yielded results discernible from the color change of the pH indicator dye. The assay showed a detection limit of approximately 0.5 µL of blood. The assay also detected XIST RNA in mixed body fluids and mock samples, indicating its potential applicability to casework samples. Taken together, our assay provides a rapid and simple strategy for screening female samples.

RNA-based short tandem repeat analysis on the D18S51 locus.

DNA typing based on short tandem repeat (STR) analysis is an effective forensic method for human identification. Some STRs are contained within the introns of protein-coding genes and are transcribed as pre-mRNAs. However, the possibility of using RNA for STR analysis is yet to be fully explored. Considering that RNA in forensic samples is relatively stable, especially under dry- and low-temperature conditions, we hypothesized that STR information could be obtained from RNA. Here, we investigated the possibility of conducting RNA-based STR analysis using the D18S51 locus as a model.

One-tube, two-step isothermal amplification of histatin 3 mRNA for saliva screening.

Saliva samples are frequently collected at crime scenes. Salivary mRNA profiling, such as that of histatin 3 (HTN3), is a highly specific approach that overcomes the limitation of traditional amylase tests. However, typical mRNA detection methods based on reverse transcription PCR (RT-PCR) are time-consuming and labor-intensive. Here, we report a one-tube, two-step isothermal amplification assay for HTN3 mRNA, which enables rapid, simple, and sensitive screening of saliva. The first step is an RT-recombinase polymerase amplification (RT-RPA) assay at 42 °C for 20 min; the second step is a loop-mediated isothermal amplification (LAMP) assay at 65 °C for 30 min. The reactions can be performed in a closed tube, and the products are detected using real-time fluorescence analysis. The assay sensitivity was 0.5 µL of saliva samples. It also detected HTN3 mRNA in mixed and mock samples, demonstrating its applicability to actual forensic samples. These findings suggest that our strategy is promising for screening of saliva from forensic samples.

Duplex loop-mediated isothermal amplification assay for simultaneous detection of human and human male DNA.

OBJECTIVE: Screening of human and human male DNA is necessary for forensic DNA analyses. Although quantitative real-time PCR (qPCR) is commonly used for detecting and quantifying these DNA targets, its use as a screening tool is time-consuming and labor-intensive. To streamline and simplify the screening process, we aimed to develop a duplex loop-mediated isothermal amplification (LAMP) assay capable of simultaneously detecting human and human male DNA in a single tube. We assessed the duplex LAMP assay for forensic application. RESULTS: For our duplex LAMP assay, we have utilized two fluorescent probes with HEX and FAM fluorophores to specifically detect human and human male DNA, respectively. The HEX (human target) signal was detected from both the male and female DNA samples, and the FAM (male target) signal was detected from only the male DNA sample. This assay has a sensitivity of 10-1 pg of DNA for both targets. Additionally, we successfully detected the two targets in the DNA samples extracted from forensically relevant body fluids, including blood, saliva, semen, and vaginal secretions.

Sperm mRNA screening by reverse transcription-recombinase polymerase amplification (RT-RPA) assay: Decision-making for differential extraction.

The presence of sperm cells is an indicator for differential extraction on sexual assault samples. In general, sperm cells are identified by microscopic analysis; however, this conventional method takes time and effort, even for trained personnel. Here, we present a reverse transcription-recombinase polymerase amplification (RT-RPA) assay targeting sperm mRNA marker (PRM1). The RT-RPA assay requires only 40 min for PRM1 detection and demonstrates a sensitivity of 0.1 µL of semen. Our results indicate that the RT-RPA assay may be a rapid, simple, and specific strategy for screening sperm cells in sexual assault samples.

Improved reverse transcription-recombinase polymerase amplification assay for blood mRNA screening: comparison with one-step RT-qPCR assay.

mRNA profiling is effective for body fluid identification because of its sensitivity, specificity, and multiplexing capability. Body fluid mRNA markers can typically be detected using RT-qPCR, RT-PCR followed by capillary electrophoresis, or targeted RNA sequencing. However, due to the multiple handling steps involved, the analysis of many forensic samples using these methods requires time and effort. Here, we describe a rapid and simple method for detecting the blood mRNA marker hemoglobin ß (HBB), intended for use in screening before definitive blood identification. We employed a reverse transcription-recombinase polymerase amplification (RT-RPA) assay that can detect target mRNA within 20 min in a single tube. For comparison, we used a one-step RT-qPCR assay. We optimized the RT-RPA assay and found that it could detect HBB from 10-3-10-4 ng of leukocyte RNA and approximately 10-3 µL of blood. The sensitivity was 10-fold lower than that of the one-step RT-qPCR assay but higher than that of the comprehensive analysis methods for definitive blood identification. Thus, the rapidity and sensitivity of the RT-RPA assay support its use as a screening tool. We also found that the RT-RPA assay was highly tolerant to common inhibitors such as humic acid, hematin, tannic acid, and melanin. Considering the inhibitor tolerability, we integrated a simple lysis method (addition of TCEP/EDTA and heating at 95 °C for 5 min) without the RNA purification process into the RT-RPA assay. This direct assay successfully detected HBB in crude blood samples. Our findings suggest that the RT-RPA assay for HBB is a promising strategy for mRNA-based blood screening.

Loop-mediated isothermal amplification assay for fluorescence analysis and lateral flow detection of male DNA.

Male DNA screening is important in forensic investigations, such as sexual assault cases. Although quantitative real-time PCR is a robust method for detection of male DNA, it is time-consuming and labor-intensive. We herein report the development of a male DNA-targeted loop-mediated isothermal amplification (LAMP) assay that can be used for both laboratory-based fluorescence analysis and on-site lateral flow detection. The two detection systems are independent, but we streamlined the reaction before the detection by introducing a fluorescence probe and biotin-labeled primer into a single reaction. This allowed the evaluation of fluorescence signal followed by lateral flow detection. Both the fluorescence and lateral flow analyses detected as low as 10 pg of male DNA. We also integrated an alkaline lysis method with our LAMP assay. The direct assay successfully detected male DNA from forensic samples without purification. The workflow requires only <40 min for fluorescence analysis and <45 min for lateral flow detection. Furthermore, when combined with a lateral flow strip, this workflow does not require any sophisticated instruments. These findings suggest that our assay is a promising strategy for on-site male DNA screening as well as laboratory-based testing.

Rapid and direct detection of male DNA by recombinase polymerase amplification assay.

Screening of male DNA is important in forensic investigations, especially sexual assault cases. Quantitative real-time polymerase chain reaction (qPCR) is widely used for the detection of male DNA. However, the use of this technique as a screening tool is time-consuming and labor-intensive. In this study, we established a recombinase polymerase amplification (RPA) assay targeting the multicopy loci on the Y-chromosome for the rapid detection of male DNA (referred to as Y-RPA). The Y-RPA assay was able to detect male DNA in less than 20 min with a sensitivity of 0.025-0.005 ng/µL. Additionally, the Y-RPA assay was highly tolerant to inhibitors; male DNA was detectable in the presence of up to 1000 ng/µL humic acid, 250 µM indigo carmine, and 500 µM hematin. Then, considering its tolerance to inhibitors, we examined the feasibility of the direct Y-RPA assay. The alkaline lysis protocol (addition of sodium hydroxide and heating at 95 °C for 5 min) was employed for preparing the DNA template. The Y-RPA assay successfully detected male DNA using crude DNA extracted from blood, saliva, and semen samples. This approach enabled the screening of male DNA within approximately 30 min (5 min for lysis and 20 min for Y-RPA). These findings suggest that the Y-RPA assay is a promising screening tool for the rapid, simple, and efficient detection of male DNA.

Rapid detection of blood and semen mRNA markers by reverse transcription-recombinase polymerase amplification.

Body fluid identification is crucial for crime scene reconstruction. Recently, messenger RNA (mRNA) profiling has been an effective approach for body fluid identification. In general, mRNA is detected by real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) or end-point RT-PCR; however, these conventional methods are time-consuming and require extensive sample processing. Therefore, we developed a rapid and simple method for the detection of blood and semen mRNA markers by reverse transcription-recombinase polymerase amplification (RT-RPA). First, we screened mRNA markers for blood and semen and selected hemoglobin beta (HBB) and protamine 1 (PRM1), respectively, based on amplification specificity. Under optimized conditions, our RT-RPA assay detected HBB and PRM1 mRNAs within 20 min at a constant temperature of 42 °C. The detection limits for the assay were 0.01 ng/µL leukocyte RNA for HBB and 0.2 ng/µL semen RNA for PRM1. In addition, our RT-RPA assay exhibited high specificity and accuracy for HBB and PRM1 mRNA detection from mixed samples. Furthermore, as RPA has been reported to possess inhibitor tolerance, we evaluated the feasibility of direct RT-RPA for HBB mRNA detection. This direct approach reduced the number of processing steps and time required for template preparation and enabled the successful detection of HBB mRNA within 45 min from sample preparation. These findings suggest that RT-RPA is a useful method for mRNA-based blood and semen identification.

Knee Flexion Angle Following Total Knee Arthroplasty Relates to a Preoperative Range of Motion of the Hip.

BACKGROUND: Many factors have been reported to affect postoperative range of knee flexion after total knee arthroplasty (TKA); however, no study has reported the impact of preoperative range of motion of the hip to the postoperative flexion angle of the knee thus far. METHODS: Of 38 consecutive patients who underwent posterior-stabilized TKA, we assessed 21 patients after excluding 17 patients who met exclusion criteria. The range of motion of the knee and the hip, age, body-mass index, serum albumin level, HbA1c, Kellgren-Lawrence grade, knee extension strength and radiological femorotibial angle as well as postoperative knee flexion angle at three months were evaluated. The preoperative data and the knee flexion angle at three months after TKA were compared using Spearman's rank correlation coefficient. RESULTS: Knee flexion angle at three months after TKA was positively correlated with preoperative flexion (ρ = 0.616, p = 0.007) and external rotation angle (ρ = 0.576, p = 0.012) of the hip as well as preoperative knee flexion angle (ρ = 0.797, p = 0.001). There were no correlations between postoperative knee flexion angle and other preoperative data. CONCLUSIONS: Patients with restricted flexion and/or external rotation of the hip may have contractures of Gluteus maximus, Gluteus medius and Tensor fasciae latae, which can cause hypertension of iliotibial tract. It may cause decreased internal rotation of the tibia when the knee is flexed, which affects postoperative knee flexion angle, thus limited flexion and/or external rotation of the hip might restrict knee flexion angle following TKA.

Rapid screening method for male DNA by using the loop-mediated isothermal amplification assay.

Screening for male-derived biological material from collected samples plays an important role in criminal investigations, especially those involving sexual assaults. We have developed a loop-mediated isothermal amplification (LAMP) assay targeting multi-repeat sequences of the Y chromosome for detecting male DNA. Successful amplification occurred with 0.5 ng of male DNA under isothermal conditions of 61 to 67 °C, but no amplification occurred with up to 10 ng of female DNA. Under the optimized conditions, the LAMP reaction initiated amplification within 10 min and amplified for 20 min. The LAMP reaction was sensitive at levels as low as 1-pg male DNA, and a quantitative LAMP assay could be developed because of the strong correlation between the reaction time and the amount of template DNA in the range of 10 pg to 10 ng. Furthermore, to apply the LAMP assay to on-site screening for male-derived samples, we evaluated a protocol using a simple DNA extraction method and a colorimetric intercalating dye that allows detection of the LAMP reaction by evaluating the change in color of the solution. Using this protocol, samples of male-derived blood and saliva stains were processed in approximately 30 min from DNA extraction to detection. Because our protocol does not require much hands-on time or special equipment, this LAMP assay promises to become a rapid and simple screening method for male-derived samples in forensic investigations.

Simulation of the optimal femoral insertion site in medial patellofemoral ligament reconstruction.

PURPOSE: To develop and validate a new simulation system to predict the optimal femoral insertion site of the medial patellofemoral ligament (MPFL) using preprogrammed conditions of graft length change. METHODS: A computed tomography scan was performed for constructing bone surface models of the patella and the femur. Lateral radiographs of the knee and axial radiographs of the patellofemoral joint at knee flexion were used for constructing a three-dimensional patellofemoral joint model by 3D-2D image matching at each knee flexion angle. To determine the optimal femoral insertion site, the following three conditions were devised: (1) MPFL behaves isometric from 0° to 60°, (2) MPFL is most taut at full extension, and (3) MPFL is slack at more than 60° of knee flexion. Every condition was applied to the femoral bone surface model, and the area that fulfilled all three conditions was defined as the optimal femoral insertion site of MPFL. Twenty knees of ten healthy volunteers were assessed to verify the simulation. Comparison between simulated optimal femoral insertion and anatomical insertion was done. RESULTS: The mean simulated optimal femoral insertion was close to the anatomical insertion site. There were no significant differences in the proximal-distal position and anterior-posterior position between the simulated insertion and the anatomical insertion sites. CONCLUSION: The system can be useful for predicting the optimal femoral insertion site as a part of a preoperative plan for MPFL reconstruction, and it may help surgeons to determine the optimal femoral insertion site during MPFL reconstruction.

Tibial tubercle osteotomy with screw fixation for total knee arthroplasty.

This study investigated the efficacy of tibial tubercle osteotomy (TTO) with screw fixation as part of the surgical treatment of primary complicated total knee arthroplasty (TKA) and revision TKA. From January 2000 to April 2011, 15 patients (15 knees) underwent revision TKA and 20 patients (21 knees) underwent primary TKA. The average patient age was 68.7±8.7 years. Patients underwent follow-up at the authors' institution for an average of 60.6±32.9 months. Comparison of preoperative and postoperative Knee Society Scores and Knee Society Functional Scores showed significant postoperative improvement (P<.05). Moreover, postoperative range of motion of the knee improved from 88.5°±33.8° to 104.3°±18.2° (P<.05). Radiographic assessment showed that the average period to bone union was 10.8±5 weeks (range, 5-28 weeks), the average length of the bone fragment was 59.4±5.9 mm, the average width at the proximal end was 18.9±2.9 mm, and the average thickness at the proximal end of the osteotomy was 10.3±1.2 mm. Tibial tubercle osteotomy provided wide exposure for TKA while protecting the extensor mechanism. Solid bone-to-bone fixation was achieved using TTO with 2 screws, and although the overall complication rate was 8.3%, none of the complications were associated with TTO itself. It is recommended that the bone fragment be 60 mm long, 20 mm wide, and 10 mm thick at the proximal end. Appropriate size of the osteotomized bone and solid screw fixation are essential to prevent complications during this procedure.

No difference between double-high insert and medial-pivot insert in TKA.

PURPOSE: To compare the clinical midterm results in ADVANCE total knee arthroplasty (TKA) with double-high (DH) insert, with same type implant with medial-pivot (MP) insert. METHOD: Forty ADVANCE TKAs were randomly divided into two groups, and two different design insert, DH insert, and MP insert were used in each group. At midterm, 4-5 years after surgery, Knee Society Scores (KSS), Knee Society Functional Scores (KSFS), range of motion (ROM), and UCLA activity score were assessed and reported in this study. RESULTS: Midterm clinical results, including ROM and KSS, were comparable with both groups. KSFS and UCLA activity score were equally good between the two groups. CONCLUSION: The results in this study revealed equally good clinical results with these types of implants at midterm follow-up, although the significant better ROM has not achieved by using DH insert. We concluded that the selection of inserts only could not achieve the better clinical results, including ROM and activity level in this study. LEVEL OF EVIDENCE: Therapeutic studies-investigating the results of treatment, Level II.

Tibial internal rotation is affected by lateral laxity in cruciate-retaining total knee arthroplasty: an intraoperative kinematic study using a navigation system and offset-type tensor.

PURPOSE: The purpose of this study was to test the hypothesis that intraoperative soft-tissue balance assessed by an offset-type tensor influences post-operative knee kinematics after cruciate-retaining (CR) total knee arthroplasty (TKA). METHODS: The influence of intraoperative soft-tissue balance on knee kinematics in CR-TKA was retrospectively analysed in 30 patients. Intraoperative soft-tissue balance parameters such as varus angle (varus ligament balance), joint component gap (centre gap), and medial and lateral compartment gaps were measured in the navigation system while applying 40-lb joint distraction force at 0°, 10°, 30°, 60°, 90°, and 120° of knee flexion using an offset-type tensor with the patella reduced. Tibial internal rotation and tibial anterior translation were measured as the differences between the values at 60° and 120° of flexion using the navigation system. Correlations between the soft-tissue parameters and post-operative knee kinematics were analysed. RESULTS: The varus ligament balance was positively correlated with tibial internal rotation at 60° and 90° of flexion (R = 0.54, P < 0.05; R = 0.60, P < 0.01, respectively). Furthermore, the joint component gap was positively correlated with tibial internal rotation at 90° of flexion (R = 0.44, P < 0.05), and the lateral compartment gap was positively correlated with tibial internal rotation at 60°, 90°, and 120° of knee flexion. CONCLUSIONS: The intraoperative varus ligament balance and joint component gap values were factors that predicted post-operative knee kinematics after CR-TKA. Lateral laxity at mid-to-deep knee flexion plays a significant role in tibial internal rotation. LEVEL OF EVIDENCE: III.

The influence of the tibial slope on intra-operative soft tissue balance in cruciate-retaining and posterior-stabilized total knee arthroplasty.

PURPOSE: This study aims to make clear the influence of the tibial slope on intra-operative soft tissue balance measurements using a tensor in cruciate-retaining and posterior-stabilized total knee arthroplasty (TKA). METHODS: Forty patients with osteoarthritis of the knee received TKAs (20 cruciate-retaining TKAs and 20 posterior-stabilized TKA). Soft tissue balance was measured using an offset type tensor at 0, 10, 45, 90, 135 degrees of knee flexion. The tibial slopes were measured by post-operative lateral radiograph. The correlation between the tibial slope and values of soft tissue balance were assessed. RESULTS: Joint component gap at 90° (R = 0.537, p < 0.01) and 135° (R = 0.463, p < 0.05) of flexion and joint component gap change value of 90-0° (R = 0.433, p < 0.05) showed positive correlations with tibial slope in posterior-stabilized TKA. There was no relationship between the tibial slope and the value of soft tissue balances in cruciate-retaining TKA. CONCLUSIONS: In the present study, we confirmed that increasing the tibial slope resulted in a larger flexion gap compared to extension gap in posterior-stabilized TKA. Surgeons should be aware that increasing the tibial slope is one factor responsible for widening the flexion-extension gap difference in posterior-stabilized TKA.

Biomechanical analysis of the knee with partial anterior cruciate ligament disruption: quantitative evaluation using an electromagnetic measurement system.

PURPOSE: To investigate the biomechanical function of anterior cruciate ligament (ACL) remnants in ACL-deficient knees with both partial and complete tears. METHODS: Twenty partial ACL-deficient (group P), 20 complete ACL-deficient (group C), and 40 contralateral ACL-intact knees were examined. The end point during the Lachman test, side-to-side differences of KT-1000 measurements, and the pivot shift test were evaluated. Additionally, the side-to-side difference of anterior tibial translation during the Lachman test and the acceleration during the pivot shift test were calculated using an electromagnetic measurement system (EMS). RESULTS: The end point was found in 9 patients in group P, whereas it was not detected in group C. In KT-1000 measurements, the mean side-to-side differences were 3.8 ± 2.4 mm in group P and 5.4 ± 2.3 mm in group C. There was a significant difference between these 2 groups (P < .05). In the pivot shift test evaluation in group P, one patient was evaluated as grade 0, 17 patients as grade 1+, and 2 patients as grade 2+. In group C, 10 patients were evaluated as grade 1+, 9 patients as grade 2+, and one patient as grade 3+. Using the EMS, mean side-to-side differences during the Lachman test were 3.1 ± 2.1 mm in group P and 7.2 ± 3.2 mm in group C. The anterior-posterior displacement in group P was significantly less than that in group C (P < .05). In the quantitative pivot shift test, the mean acceleration in the contralateral ACL-intact knees was -632.7 ± 254.5 mm/s(2), whereas it was -1107.5 ± 398.9 mm/s(2) in group P and -1652.2 ± 754.9 mm/s(2) in group C. Significant differences were detected between the 3 knee conditions (P < .05). CONCLUSIONS: The quantitative assessments of knees with partial ACL ruptures during the Lachman test and the pivot shift test using the EMS showed less laxity than did knees with complete ACL tears, whereas their laxity was greater than the contralateral knees with intact ACLs. LEVEL OF EVIDENCE: Level III, diagnostic study of nonconsecutive patients.

Kinematic factors affecting postoperative knee flexion after cruciate-retaining total knee arthroplasty.

PURPOSE: The purpose of this study was to investigate kinematic factors affecting postoperative knee flexion after cruciate-retaining (CR) total knee arthroplasty (TKA) by analysing pre- and postoperative knee kinematics. METHODS: We retrospectively analysed 58 patients with osteoarthritis who received the same implant series. Pre- and postoperative kinematics were measured intraoperatively using a navigation system. As a clinical outcome, we measured the knee flexion angle before and one year after surgery. Correlations among pre- and postoperative kinematics and postoperative flexion were analysed using simple linear regression analyses. RESULTS: Preoperative knee kinematics, including tibial internal rotation and anterior translation (R = 0.87, P < 0.001; R = 0.53, P < 0.001, respectively), were significantly correlated with postoperative kinematics. Preoperative varus-valgus movements improved significantly postoperatively; however, tibial internal rotation remained unchanged. Furthermore, postoperative knee flexion angle was significantly correlated with postoperative tibial internal rotation (R = 0.45, P < 0.001). CONCLUSIONS: Preoperative knee kinematics were unchanged even after CR-TKA. Postoperative tibial internal rotation is one of the most important factors affecting postoperative knee flexion.

The influence of patella height on soft tissue balance in cruciate-retaining and posterior-stabilised total knee arthroplasty.

PURPOSE: Although the patella reduced or everted position has recently been recognised as an important factor influencing soft tissue balance during assessment in total knee arthroplasty (TKA), the influence of patella height on soft tissue balance has not been well addressed. Therefore, the relationship between soft tissue balance and patella height was investigated and differences between cruciate-retaining (CR) and posterior-stabilised (PS) TKA were compared. METHODS: Forty consecutive patients blinded to the type of implant received, were randomised prospectively. Using lateral radiographs, pre-operative patella height was measured. Using an offset-type tensor designed to measure the soft tissue balance with a reduced patellofemoral (PF) joint and femoral component in place, soft tissue balance was intra-operatively assessed in CR TKA (n = 20) and PS TKA (n = 20) in osteoarthritic patients. The joint component gap and varus ligament balance at zero, ten, 45, 90 and 135° of knee flexion with the patella reduced were measured. RESULTS: In PS TKA, the joint component gap positively correlated with patella height at 90 and 135° of knee flexion. However, there was no correlation between joint component gap and patella height at other flexion angles in PS TKA and any flexion angle in CR TKA. Varus ligament balance showed no significant correlation with patella height in either CR or PS TKA. CONCLUSION: Analysis of soft tissue balance and patella height only showed a positive correlation in joint component gap at a high flexion angle (90 and 135°) in PS TKA but not in other parameters examined. Pre-operative measurement of patella height may be an important factor for predicting an intra-operative flexion gap in PS TKA.

Different pattern in gap balancing between the cruciate-retaining and posterior-stabilized total knee arthroplasty.

PURPOSE: In order to permit soft tissue balance under more physiological conditions during total knee arthroplasties (TKAs), an offset-type tensor was developed to obtain soft tissue balancing throughout the range of motion with reduced patello-femoral (PF) and aligned tibiofemoral joints. The main purpose of the present study was to assess intra-operative soft tissue balance using a navigation system with the offset-type tensor in both cruciate-retaining (CR) and posterior-stabilized (PS) TKAs. METHODS: One hundred and twenty TKAs--80 CR and 40 PS--were performed in patients with varus-type osteoarthritis using a computed tomography-free navigation system. The offset-type TKA tensor with a reduced and repaired PF joint and femoral component in place was used with the tibia first gap technique to balance soft tissues (joint component gap and ligament balance) at 0°, 10°, 30°, 60°, 90°, and 120° of flexion. The achievement in equalized rectangular gap at extension and flexion--joint component gap within ±3 mm between extension and flexion and ligament balance within ±3° at extension and flexion--was assessed retrospectively. RESULTS: Both types of implants showed similar patterns of soft tissue balance throughout the range of motion, whereas PS TKA had larger values especially at 60° or 90° of flexion than did CR TKA. In the achievement of equalized rectangular gaps at extension and flexion, CR TKA was superior to PS TKA. CONCLUSION: Using the tibia first gap technique with the tensor allows appropriate soft tissue balancing, especially in CR TKA. LEVEL OF EVIDENCE: Therapeutic studies, Level II.