Clinical Relevance of Posterior Osteophyte Formation in Ultra-congruent Total Knee Arthroplasty: Midterm Radiographic Rollback and Impingement Analysis.

Background: Posterior femoral condylar osteophytes were frequently observed in patients with the ultra-congruent (UC) deep-dish design prosthesis. Therefore, the purpose of the present study was to verify the clinical relevance of osteophyte formation in the UC design. Methods: From March 2014 to February 2018, a comparative study was conducted on 96 knees using the UC design. They were divided into 2 groups (group 1: osteophyte +, group 2: osteophyte -). Intraoperative findings, indirect femoral rollback assessment using 30° flexion and active full flexion lateral radiographs, serial change of the osteophyte, and outcomes were compared. Results: The mean follow-up period was 49.35 ± 3.47 months in group 1 and 47.52 ± 3.37 months in group 2. Posterior component coverage was significantly different between the groups: group 1 exhibited more underhang and group 2 exhibited more overhang (p = 0.022). On the indirect assessment of the femoral rollback, there was a statistically significant difference in deep flexion and change in distance (p < 0.001 and p < 0.001, respectively). There was no statistical difference between the 2 groups in the American Knee Society knee and function score, and group 2 showed significant improvement in pain compared to group 1 in Western Ontario and McMaster University Arthritis Index pain score (p = 0.029). Conclusions: Posterior condylar osteophyte formation was related to posterior impingement. It was more frequently observed in the underhang of the femoral component and insufficient femoral rollback. In addition, it changed with time and caused negative effects, including a gradual decrease in flexion and more pain.

Age and medial compartmental OA were important predictors of the lateral compartmental OA in the discoid lateral meniscus: Analysis using machine learning approach.

PURPOSE: The objective of this study was to develop a machine learning model that would predict lateral compartment osteoarthritis (OA) in the discoid lateral meniscus (DLM), from which to then identify factors contributing to lateral compartment OA, with a key focus on the patient's age. METHODS: Data were collected from 611 patients with symptomatic DLM diagnosed using magnetic resonance imaging between April 2003 and May 2022. Twenty features, including demographic, clinical and radiological data and six algorithms were used to develop the predictive machine learning models. Shapley additive explanation (SHAP) analysis was performed on the best model, in addition to subgroup analyses according to age. RESULTS: Extreme gradient boosting classifier was identified as the best prediction model, with an area under the receiver operating characteristic curve (AUROC) of 0.968, the highest among all the models, regardless of age (AUROC of 0.977 in young age and AUROC of 0.937 in old age). In the SHAP analysis, the most predictive feature was age, followed by the presence of medial compartment OA. In the subgroup analysis, the most predictive feature was age in young age, whereas the most predictive feature was the presence of medial compartment OA in old age. CONCLUSION: The machine learning model developed in this study showed a high predictive performance with regard to predicting lateral compartment OA of the DLM. Age was identified as the most important factor, followed by medial compartment OA. In subgroup analysis, medial compartmental OA was found to be the most important factor in the older age group, whereas age remained the most important factor in the younger age group. These findings provide insights that may prove useful for the establishment of strategies for the treatment of patients with symptomatic DLM. LEVEL OF EVIDENCE: Level III.

Arthroscopic Meniscal Repair and Meniscectomy for Adult Discoid Lateral Meniscus Results in Progression to Valgus Alignment and Lateral Compartment Degeneration Compared With Nonoperative Treatment and Nondiscoid Lateral Meniscus.

PURPOSE: To analyze the effect of the arthroscopic meniscal procedure in adult discoid lateral meniscus (DLM) according to the age and meniscal-preserving by making comparisons with the nondiscoid lateral meniscus (N-DLM). METHODS: From March 2014 to October 2020, a comparative analysis was performed in adults with DLM who underwent arthroscopic meniscal procedures (operative DLM: 134 knees), nonoperative treatment (nonoperative DLM: 56 knees), and adult N-DLM who underwent arthroscopic meniscal procedures (operative N-DLM: 64 knees). These patients were between 20 and 65 years old and completed a minimum follow-up of 2 years. Patients with DLM who underwent arthroscopic procedure were divided into subgroups according to age and extent of the meniscal-preserving. The following parameters were assessed and compared between the groups: (1) coronal limb alignment, (2) osteoarthritis grade, and (3) clinical outcomes and the minimal clinically important difference. RESULTS: The coronal limb alignment was significantly changed to valgus in the order of operative DLM, N-DLM, and nonoperative DLM (Δ mechanical hip-knee-ankle angle: 3.23 ± 1.85 vs 1.35 ± 1.03° vs -0.57 ± 1.88°; P < .05). Operative DLM showed most prominent osteoarthritic change in the lateral compartment, followed by the N-DLM and nonoperative DLM groups (40.3% vs 17.2% vs 5.3%; P < .05). These changes in operative DLM were more prominent in older adults who underwent meniscal-sacrificing procedures and resulted in less-satisfactory clinical outcomes (all P < .05). CONCLUSIONS: Arthroscopic surgery for adult DLM resulted in progression to valgus alignment and lateral compartment degeneration compared with nonoperative treatment and arthroscopic surgery of the adult N-DLM. Old ager and having a meniscal-sacrificing procedure showed more rapid radiographic changes and lower clinical outcomes. LEVEL OF EVIDENCE: Level III, retrospective comparison study.

Maintenance of the joint line and posterior condylar offset are the most notable variables for successful outcomes of revision total knee arthroplasty.

INTRODUCTION: Controversy regarding which variables should be prioritized for better outcomes in revision total knee arthroplasty (RTKA) exists. This study aimed to comprehensively analyze the variables affecting RTKA outcomes. MATERIALS AND METHODS: We retrospectively identified 87 RTKAs in 82 patients who were performed between March 2014 and February 2020. Range of motion (ROM), including flexion contracture (FC) and further flexion (FF), was analyzed according to the covariates. The covariates included mode of failure, joint line position, anteroposterior (AP) position, rotational alignment of the femoral component, and patellofemoral alignment. The differences between the final follow-up values of each RTKA variable and those of the native knee were evaluated. The clinical outcomes were evaluated. RESULTS: No significant differences were observed between the joint line positions of the RTKA and native knees. The patellar and AP positions of the femoral component were restored to pre-TKA values. The femoral component had an external rotation of 2.78° compared with the native knee. In multivariable stepwise regression analysis, restoration of the adductor tubercle joint line and posterior condylar offset (PCO) were significant variables affecting ROM. Septic RTKA (33 knees) resulted in poor FF outcomes (p = 0.030) and Western Ontario and McMaster Universities Osteoarthritis Index stiffness (WOMAC S) scores (p < 0.001), compared with aseptic RTKA (54 knees). CONCLUSIONS: Restoration of the joint line position and PCO are crucial factors for improved ROM in RTKA. Joint line elevation in RTKA resulted in worse ROM than joint line lowering. In addition, RTKA due to septic failure had inferior ROM and WOMAC S scores compared with RTKA due to aseptic failure. LEVEL OF EVIDENCE: Level III, cohort study.

Constitutional alignment predicts medial ligament balancing in mechanically aligned total knee arthroplasty for varus knees.

PURPOSE: The aim of this study was to identify if constitutional alignment and preoperative radiologic parameters determined whether medial gap balancing was required in mechanically aligned total knee arthroplasty (TKA). METHODS: Two hundred and sixty three patients with 394 consecutive knees who underwent primary TKAs were retrospectively analysed in this study. Selective sequential multiple needle puncturing (MNP) was performed for medial ligament balancing when required. Constitutional alignment, which was determined using the Coronal Plane Alignment of the Knee (CPAK) classification, as well as preoperative and postoperative radiologic parameters was evaluated to identify factors which predicted the need for MNP. RESULTS: One hundred and fifty eight (40.1%) knees required medial ligament balancing with MNP. Patients who required MNP during surgery had significantly more constitutional varus, more varus preoperative mechanical Hip-Knee-Ankle angle (mHKA), smaller preoperative medial proximal tibial angle (MPTA) and a larger change in mHKA and MPTA after surgery than those who did not. Patients with constitutional varus also had a higher incidence of having had MNP to both anterior and posterior superficial medial collateral ligament (sMCL) fibres. There was no significant difference in preoperative lateral distal femoral angle (LDFA), posterior tibial slope (PTS) and varus-valgus difference (VVD) between groups. CONCLUSION: Ligament balancing using MNP was determined by constitutional alignment rather than medial soft tissue contracture. Patients with constitutional varus who had a larger medio-lateral gap difference in extension also had a higher incidence of having had MNP to both anterior and posterior sMCL fibres. LEVEL OF EVIDENCE: Retrospective comparative study, level IV.

Prior tuberosity screw fixation of the osteotomized tubercle can lead to favorable outcomes in retro-tubercular bi-planar opening wedge high tibial osteotomy.

BACKGROUND: Exact information regarding fixing the tuberosity screw during retro-tubercular opening-wedge high tibial osteotomy (RT-OWHTO) is still lacking. The purpose of this study was to determine whether prior tuberosity screw fixation before plate fixation of main osteotomy fragment can prevent complications associated with tuberosity screw. METHODS: From 2019 to 2021, patients who underwent RT-OWHTO were divided into two groups (group I, prior tuberosity screw fixation; group II, later tuberosity screw fixation). A total of 49 and 44 knees were included in groups I and II, respectively. Plain radiographs and computed tomography (CT) were used to analyze the parameters of tuberosity screw fixation, neurovascular (NV) safety and osteotomy configurations. Clinical outcomes and post-operative complications were assessed. RESULTS: The delta (Δ) of the deformation angle of the tuberosity (P = 0.002), delta (Δ) of the posterior tibial slope (PTS) (P < 0.001), extruded screw length (P < 0.001), and retro-tuberosity tip distance (P < 0.001) of group I were significantly smaller than those of group II. All tuberosity screws were fixed medially to the NV structures. Post-operative tuberosity fracture occurred in one knee (2%) in group I and in 10 knees (23%) in group II (P = 0.003). CONCLUSIONS: RT-OWHTO with prior tuberosity screw fixation can minimize the risk of tuberosity fracture and an increase in the PTS. It can also prevent NV injuries by reducing extruded tuberosity screw length and fixing it medially from the NV structures.

Constitutional and postoperative joint line obliquity can predict serial alignment change after opening-wedge high tibial osteotomy: analysis using coronal plane alignment of the knee classification.

PURPOSE: The purposes of this study were (1) to clarify the distribution of the Coronal Plane Alignment of the Knee (CPAK) phenotype in patients who underwent medial opening-wedge high tibial osteotomy (OWHTO) and (2) to identify the predictive factors for postoperative serial alignment changes after OWHTO by analyzing constitutional phenotypes. METHODS: Patients who underwent OWHTO between March 2014 and December 2019 were retrospectively evaluated. Those who completed a minimum follow-up of 3 years were divided into three groups based on the direction of alignment changes from postoperative 3 months to the final follow-up: Group 1 (varus direction) when the weight-bearing line ratio (WBLR) change was less than - 4%, Group 2 (maintained) when the WBLR change was between - 4% and 4%, and Group 3 (valgus direction) when the WBLR change was greater than 4%. The following parameters were assessed serially and compared between the groups: (1) radiologic parameters of coronal limb alignment such as joint line obliquity (JLO), (2) CPAK phenotypes, and (3) clinical outcomes. RESULTS: In total, 163 knees were included, and the average duration of follow-up was 4.8 ± 1.6 years. More apex distal JLO was observed in the order of Group 1, 2, and 3 at all times (all p < 0.05). The most common CPAK type was type (I + II) (constitutional: apex distal JLO) + type (V + VI) (postoperative 3 months: neutral JLO) in Group 1 (29.4%; p = 0.000); otherwise, the most common CPAK type was type (IV + V) (constitutional: neutral JLO) + type (VIII + IX) (postoperative 3 months: apex proximal JLO) in Group 3 (11.7%; p = 0.000). Clinical outcomes did not differ between the groups. CONCLUSION: Constitutional and postoperative JLO were predictive factors of postoperative alignment changes after OWHTO. Constitutional apex distal and postoperative neutral JLO had a tendency for varus alignment progression, whereas constitutional neutral and postoperative apex proximal JLO had a tendency for valgus alignment progression. LEVEL OF EVIDENCE: Retrospective cohort study; Level III.

Does referencing system affect the selection of implant size, position and gap balance in total knee arthroplasty?

BACKGROUND: (1) To evaluate if referencing system affects selection of implant size, position, and gap balance in total knee arthroplasty (TKA) with the use of contemporary implant designs and (2) to describe the authors' intraoperative sizing strategy using anterior referencing (AR) and posterior referencing (PR) systems. METHODS: This was a retrospective review of 270 consecutive patients (397 knees) who underwent primary TKA with an AR or PR system. Selection of implant size, mediolateral and anteroposterior alignment of the femoral component, as well as gaps were compared between groups. RESULTS: In the AR group, more patients had femoral components which were upsized or downsized compared to those in the PR group (29.5% vs 12.0% respectively) and in patients who underwent bilateral TKA, 49.4% of those in the AR group had femur component size asymmetry. The AR group had better medio-lateral (ML) fit over the distal cutting surface area, smaller change in anterior offset but higher incidence of anterior notching when compared to the PR group. Posterior condylar offset (PCO) was restored in both groups and gap differences in flexion-extension and ML were comparable. There was also no difference in clinical scores and ROM between groups at 2-years follow-up. CONCLUSION: In this study, conventional implications related to referencing system were not observed. In practice, AR systems can restore PCO while PR systems do not result in increased anterior notching or anterior overstuffing. Differences observed in this study are most likely related to implant design specifics and surgical technique.

The use of an anatomic tibial baseplate in total knee arthroplasty optimizes coverage without compromising rotation: A propensity-matched evaluation.

BACKGROUND: The aims of this study were (1) to compare in vivo coverage and rotational alignment of 2 tibial component designs: anatomic and symmetrical; and (2) to determine if coronal deformity and tibial torsion were related to rotation and coverage. METHODS: Postoperative CT scans of 200 propensity score-matched patients who underwent TKA with either an anatomic (ATC) or symmetrical tibia component (STC) were analyzed. Rotation was measured using four axes: surgical transepicondylar axis (sTEA), Berger's protocol, medio-lateral (ML) axis and posterior borders of the tibial plateau, while coverage was assessed by measuring fit and surface area. The relationship between coronal deformity, tibial torsion, rotation, and coverage was investigated. RESULTS: Overall, STCs had more internal rotation when measured using the sTEA (-0.6° ± 3.5 vs 0.5° ± 3.6, p = 0.03), Berger's protocol (-21.6° ± 7.1 vs -17.9° ± 6.2, p = 0.000) and ML axes (2.9° ± 3.9 vs 8.1° ± 5.1, p = 0.000) compared to ATCs. STCs also had more posteromedial underhang (-3.3 mm ± 2.4 mm vs -1.7 mm ± 2.5 mm, p = 0.000) but smaller change in tibial torsion postoperatively (-18.4° ± 9.9° vs -13.1° ± 9.4°, p = 0.000). Tibial torsion was more pronounced in valgus than varus knees both preoperative (-25.4° ± 6.5° vs -20.2° ± 9.3°, p = 0.02) and postoperatively (-19.7° ± 7.2° vs -14.7° ± 10.3°, p = 0.04), but there was no difference in postoperative tibial torsion between ATCs and STCs in this subgroup. CONCLUSION: The use of an anatomic tibial baseplate optimizes coverage by reducing posterolateral overhang and posteromedial underhang. It also achieved better rotational profiles compared to STCs. However, it resulted in a larger change in tibial torsion after TKA.

The development of machine learning algorithms that can predict patients satisfaction using baseline characteristics, and preoperative and operative factors of total knee arthroplasty.

BACKGROUND: Patient satisfaction following primary total knee arthroplasty (TKA) is a crucial part to evaluate the success of the procedure. The purpose of this study was to develop to predict patient satisfaction following TKA. METHODS: Satisfaction outcome data after 435 consecutive conventional TKAs performed between August 2020 and December 2021 were retrospectively collected. The total 26 input data were collected. The most favorable algorithm was first found using logistic regression (LR) and machine learning (ML) algorithms. To evaluate the predictive performance of the models, both area under curve (AUC) and F1-score were used as the primary metrics. The shapley additive explanations (SHAP) feature explanation in XGBoost and LR analysis were performed to interpret the model. RESULTS: The performance of extreme gradient boosting classifier (XGBoost) was only higher than that of conventional LR in AUC (0.782 vs. 0.689). Comparing the F-1 score, only XGBoost showed better performance than LR (0.857 vs. 0.800). The most predictive feature in XGBoost was Short Form-36 physical and mental component summary scores (SF-36 MCS), followed by Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain, Bone mineral density (BMD). In the LR analysis, lumbar spine disease, WOMAC pain, and BMD were statistically significant. CONCLUSION: XGboost showed the best performance and was superior to conventional LR in the prediction of patient satisfaction after TKA. The SF-36 MCS was the most important feature in the ML model. WOMAC pain and BMD were meaningful variables and demonstrated a linear relationship with satisfaction in both the LR and ML models. LEVEL OF EVIDENCE: Retrospective cohort study; Level of evidence 3.

Association Between Tunnel Position, Tunnel Angle, Graft Signal Intensity, and Graft Thickness in the Reconstructed Posterior Cruciate Ligament.

Background: An appropriate tunnel position, tunnel angle, and tunnel-graft angle are important factors for maintaining the stability and mechanical properties of a posterior cruciate ligament (PCL) graft. Purpose: To evaluate the association between tunnel position, tunnel angle, graft signal intensity ratio (SIR), and graft thickness after remnant-preserving PCL reconstruction. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Included were patients who had undergone remnant-preserving single-bundle PCL reconstruction using a tibialis anterior allograft between March 2014 and September 2020 and who had minimum 12-month postoperative magnetic resonance imaging scans. Tunnel position and angle were evaluated via 3-dimensional computed tomography, and their association with graft SIR on both the femoral and the tibial sides was determined. Graft thickness and SIR at 3 areas of the graft were evaluated and compared, and their association with tunnel-graft angle was also determined. Results: Overall, 50 knees (50 patients; 43 male, 7 female) were included. The mean time to postoperative magnetic resonance imaging was 25.8 ± 15.8 months. The mean SIR of the graft's midportion was higher compared with that of the proximal and distal portions (P = .028 and P < .001, respectively), and the SIR of the proximal portion was higher compared with that of the distal portion (P = .002). The femoral tunnel-graft angle was more acute than the tibial tunnel-graft angle (P = .004). A more anteriorly and distally located femoral tunnel led to a less acute femoral tunnel-graft angle (P = .005) and a decreased SIR of the proximal portion (P = .040), and a more laterally located tibial tunnel was associated with a less acute tibial tunnel-graft angle (P = .024) and a reduced SIR of the distal portion (P = .044). The mean thicknesses of the graft's midportion and distal portion were larger than that of the proximal portion (P < .001). The SIR of the graft's midportion was positively correlated with its thickness (r = 0.321; P = .023). Conclusion: The SIR of the proximal portion of the graft around the femoral tunnel was higher than that of the distal portion around the tibial tunnel. An anteriorly and distally positioned femoral tunnel and a laterally positioned tibial tunnel resulted in less acute tunnel-graft angles that were associated with decreased signal intensity.

Graft impingement increases anterior cruciate ligament graft signal more than acute graft bending angle: magnetic resonance imaging-based study in outside-in anterior cruciate ligament reconstruction.

PURPOSE: In this study, the relationship between patient-specific geometric factors and tunnel placement in graft impingement was identified by using magnetic resonance imaging (MRI) signal intensity of anterior cruciate ligament (ACL) grafts. METHODS: Ninety-two patients, who were treated between 2014 and 2020, were included retrospectively. These patients underwent primary remnant-preserving outside-in ACL reconstruction (ACLR) and were followed up with postoperative MRI at least one year after surgery. Plain radiographs and computed tomography (CT) were used to analyze tibial and femoral tunnel positions. Postoperative MRI was performed, at 32.8 ± 17.5 months after surgery, to evaluate the graft signal intensity, the ACL/posterior cruciate ligament (PCL) ratio (APR), ACL/muscle ratio (AMR), tunnel positions, and graft impingement. Clinical and stability outcomes were analyzed using the International Knee Documentation Committee (IKDC) subjective and objective scores, Lysholm scores, and side-to-side differences (SS-D). RESULTS: The mean APR and AMR of the proximal third of the grafts were significantly lower than those of the middle third of the grafts (p = 0.017 and p = 0.045, respectively). Multivariate regression analysis showed that there was a negative association between the mean APR and AMR of entire intra-articular ACL graft and the distance from the anterior end of the intercondylar roof to the center of the tibial tunnel in the sagittal plane (p < 0.001 and p < 0.001, respectively) and the notch width index (p < 0.001 and p = 0.002, respectively). No significant correlations were found between tunneling and geometric factors, and clinical scores or SS-D. CONCLUSIONS: Graft impingement on the anterior tibial tunnel relative to the end of the intercondylar roof and narrow notch was a more significant contributing factor on increased signal intensities of the ACL graft, compared with the acute femoral bending angle in remnant-preserving outside-in ACLR. Therefore, surgeons should focus on intercondylar notch anatomy during tibial tunnel placement to avoid roof impingement. LEVEL OF EVIDENCE: Level III.

Analysis of the determinant factor of the medial joint space width after medial opening wedge high tibial osteotomy.

INTRODUCTION: The decrease in the medial joint space width (MJSW) in patients with osteoarthritis (OA) is proportional to the degree of arthritis. The purpose of this study was to evaluate the affecting factors of the MJSW by serial radiologic assessment after medial open wedge high tibial osteotomy (MOW-HTO). MATERIALS AND METHODS: Between March 2014 and March 2019, 162 MOW-HTO knees that underwent serial radiologic assessment and follow-up MRI were enrolled. Changes in the MJSW were analyzed by dividing into three groups: group I, low quartile (< 25%); II, middle quartile (25-75%); and III, high quartile (> 75%), according to the magnitude of the MJSW. The correlation between the MJSW and weight-bearing line ratio (WBLR), hip knee ankle angle (HKA), joint line convergence angle (JLCA), medial proximal tibial angle (MPTA), mechanical lateral distal femoral angle (m-LDFA), joint line orientation angle (JLOA), and MRI cartilage status was analyzed. Multiple linear regression analysis was used to analyze factors affecting the amount of change in the MJSW. The clinical outcome was also correlated with the MJSW. RESULTS: The amount of change in the JLCA, which has the largest beta value (weight-bearing standing anteroposterior (AP) view and 45° flexion posteroanterior view (Rosenberg view) ß = - 0.699 and ß = -5.221, both p < 0.001, respectively), had the greatest contribution to the change in the MJSW. The WBLR was also related (standing AP and Rosenberg ß = 0.177 and ß = 0.264, p = 0.015 and p = 0.004, respectively). There was no statistical difference between the amount of change in the MJSW and the change in cartilage. The clinical outcomes did not differ between the groups. CONCLUSION: The JLCA was the most important contributing factor for the MJSW, followed by WBLR. This contribution was more pronounced in Rosenberg view than standing AP view. Changes in cartilage status were not related to the MJSW and JLCA. The clinical outcome was not related to the MJSW, either. Level of evidence Cohort study; level III.

Key-Point Detection Algorithm of Deep Learning Can Predict Lower Limb Alignment with Simple Knee Radiographs.

(1) Background: There have been many attempts to predict the weight-bearing line (WBL) ratio using simple knee radiographs. Using a convolutional neural network (CNN), we focused on predicting the WBL ratio quantitatively. (2) Methods: From March 2003 to December 2021, 2410 patients with 4790 knee AP radiographs were randomly selected using stratified random sampling. Our dataset was cropped by four points annotated by a specialist with a 10-pixel margin. The model predicted our interest points, which were both plateau points, i.e., starting WBL point and exit WBL point. The resulting value of the model was analyzed in two ways: pixel units and WBL error values. (3) Results: The mean accuracy (MA) was increased from around 0.5 using a 2-pixel unit to around 0.8 using 6 pixels in both the validation and the test sets. When the tibial plateau length was taken as 100%, the MA was increased from approximately 0.1, using 1%, to approximately 0.5, using 5% in both the validation and the test sets. (4) Conclusions: The DL-based key-point detection algorithm for predicting lower limb alignment through labeling using simple knee AP radiographs demonstrated comparable accuracy to that of the direct measurement using whole leg radiographs. Using this algorithm, the WBL ratio prediction with simple knee AP radiographs could be useful to diagnose lower limb alignment in osteoarthritis patients in primary care.

Medially and distally inserted tuberosity screw fixation of the osteotomized tubercle is safe and effective in retro-tubercular bi-planar opening-wedge high tibial osteotomy.

PURPOSE: The purpose of this study was to develop a safe and effective method of inserting one tuberosity screw and to determine whether retro-tubercular (RT)-Open-wedge high tibial osteotomy (OWHTO) with tuberosity screw fixation can be conducted to overcome the problem of osteotomized tubercle and produce favorable outcomes compared to RT-OWHTO without tuberosity screw fixation. METHODS: From 2018 to 2020, patients who underwent bi-planar RT-OWHTO were allocated as two groups (RT-OWHTO without tuberosity screw fixation as group I and with screw fixation as group II). Computed tomography (CT) was used to analyze osteotomy configurations such as RT gap and tip distance, and union of the main and second plane osteotomy sites. The RT gap distance was measured as the length of the osteotomy gap. The RT tip distance was measured as the length of the gap at the tip of the tibial tubercle. Post-operative complications were analyzed also. To evaluate the neurovascular (NV) approximity of screw fixation group, the pre-operative magnetic resonance imaging (MRI) images were referenced on the post-operative CT for the assessment of the safe zone. RESULTS: In total, 44 knees in group I and 46 knees in group II were enrolled. The RT gap distance (2.58 ± 0.69 mm vs. 0.57 ± 0.57 mm; p < .001) and RT tip distance (4.31 ± 1.60 mm vs. 1.48 ± 1.42 mm; p < .001) were significantly larger in group I than in group II. The sum of union grade in the second plane osteotomy site (17.93 ± 2.18 points vs. 22.24 ± 2.57 points; p < .001) was statistically different between two groups at three months post operatively. Post-operative tuberosity prominence occurred in five knees only in group I (p = 0.025), although tibial tuberosity fracture developed in seven cases in group II compared with two cases in group I with no statistical significance. NV was safe when the screw was inserted medially. CONCLUSION: RT-OWTHO with one-screw fixation for the tuberosity was effective in terms of tuberosity prominence and the union of the second plane osteotomy site. However, it also produced another problem, such as tuberosity fracture. In addition, a tuberosity screw was safe when it was inserted in the medial-distal direction. LEVEL OF EVIDENCE: Cohort study; level III.

Development of a machine learning model to predict lateral hinge fractures by analyzing patient factors before open wedge high tibial osteotomy.

PURPOSE: Several methods have been developed to prevent lateral hinge fractures (LHFs), using only classic statistical models. Machine learning is under the spotlight because of its ability to analyze various weights and model nonlinear relationships. The purpose of this study was to create a machine learning model that predicts LHF with high predictive performance. METHODS: Data were collected from a total of 439 knees with medial osteoarthritis (OA) treated with Medial open wedge high tibial osteotomy (MOW-HTO) from March 2014 to February 2020. The patient data included age, sex, height, and weight. Preoperative, determined, and modifiable factors were categorized using X-ray and CT data to create ensemble models with better predictive performance. Among the 57 ensemble models, which is the total number of possible combinations with six models, the model with the highest area under curve (AUC) or F1-score was selected as the final ensemble model. Gain feature importance analysis and the Shapley additive explanations (SHAP) feature explanation were performed on the best models. RESULTS: The ensemble model with the highest AUC was a combination of a light gradient boosting machine (LGBM) and multilayer perceptron (MLP) (AUC = 0.992). The ensemble model with the highest F1-score was the model that combined logistic regression (LR) and MLP (F1-score = 0.765). Distance X was the most predictive feature in the results of both model interpretation analyses. CONCLUSION: Two types of ensemble models, LGBM with MLP and LR with MLP, were developed as machine learning models to predict LHF with high predictive performance. Using these models, surgeons can identify important features to prevent LHF and establish strategies by adjusting modifiable factors. STUDY DESIGN: Retrospective cohort study.

One-Step Polymerase Chain Reaction-Free Nanowire-Based Plasma Cell-Free DNA Assay to Detect EML4-ALK Fusion and to Monitor Resistance in Lung Cancer.

BACKGROUND: Next-generation sequencing has mostly been used for genotyping cell-free DNA (cfDNA) in plasma. However, this assay has several clinical limitations. We evaluated the clinical utility of a novel polymerase chain reaction-free nanowire (NW)-based plasma cfDNA assay for detecting ALK fusion and mutations. PATIENTS, MATERIALS, AND METHODS: We consecutively enrolled 99 patients with advanced non-small cell lung cancer undergoing a fluorescence in situ hybridization (FISH) test for ALK fusion; ALK-positive (n = 36). The NW-based assay was performed using 50-100 µL of plasma collected at pretreatment and every 8 weeks during ALK inhibitor treatment. RESULTS: There was high concordance between the NW-based assay and the FISH test for identification of ALK fusion (94.9% with a kappa coefficient value of 0.892, 95% confidence interval [CI], 0.799-0.984). There was no difference in the response rate to the first anaplastic lymphoma kinase inhibitor between the ALK-positive patients identified by the NW-based assay and by the FISH test (73.5% vs. 72.2%, p = .931). In the ALK variant analysis, variants 1 and 3 subgroups were detected in 27 (75.0%) and 8 (22.2%) patients, respectively. Among 24 patients treated with crizotinib, variant 3 subgroup was associated with worse median overall survival than variant 1 subgroup (36.5 months; 95% CI, 0.09-87.6 vs. 19.8 months; 95% CI, 9.9-not reached, p = .004]. A serial assessment identified that ALK L1196M resistance mutation emerged before radiologic progression during crizotinib treatment. CONCLUSION: The newly developed simple NW-based cfDNA assay may be clinically applicable for rapid diagnosis of ALK fusion with its variant forms and early detection of resistance. IMPLICATIONS FOR PRACTICE: The authors developed a novel one-step polymerase chain reaction-free nanowire (NW)-based plasma cell-free DNA (cfDNA) assay. This study evaluated the clinical utility of this novel method for the diagnosis of EML4-ALK fusion in advanced non-small cell lung cancer (NSCLC). The NW-based assay and FISH test showed high concordance rate in 99 patients with advanced NSCLC. Serial cfDNA assessment demonstrated this method provided early detection of resistance before radiologic progression during crizotinib treatment. Taken together, plasma cfDNA genotyping by the NW-based cfDNA assay may be useful for the rapid diagnosis of ALK fusion, classifying variants, and early detection of resistance.