Details of a Researcher - Harato, Kengo

Papers - Harato, Kengo

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Targeted hip abductor fatigue alters trunk and lower limb biomechanics during Single-Leg landing

Harato K., Nishizawa K., Imai S., Kobayashi S., Kaneda K., Matsumoto T., Nagura T.

Scientific Reports 15 ( 1 ) 2025.12

Fatigue of the hip abductor muscles may influence lower limb biomechanics and potentially contribute to anterior cruciate ligament (ACL) injury risk. However, the effects of targeted hip abductor fatigue on trunk, pelvis and lower limb coordination during landing tasks remain unclear. The present study aimed to investigate how targeted hip abductor fatigue alters the biomechanics of the trunk, pelvis, and lower extremity during single-leg landing (SLL). Twenty healthy male recreational athletes performed SLL before and after a targeted hip abductor fatigue protocol. Kinematic and kinetic data were collected using a three-dimensional motion capture system and force plates, with analysis focused on the timing of peak vertical ground reaction force. Following fatigue, participants exhibited increased hip abduction angle and trunk right inclination, as well as decreased hip flexion and external hip abduction moment. Notably, the external knee abduction moment significantly increased post-fatigue, though it remained negative in absolute value. Increased pelvic left rotation was also observed, indicating compensatory adjustments in trunk-pelvis coordination. These adaptations indicate that targeted muscle fatigue induces complex biomechanical responses across the kinetic chain, rather than uniformly increasing injury risk through valgus-prone mechanics. While the observed changes may reflect stabilizing strategies under fatigue, their implications for ACL loading require further clarification. The current study highlights the relevance of considering whole-body biomechanical responses to targeted fatigue and contributes to a more detailed understanding of neuromuscular control during landing. These findings may support the refinement of injury prevention approaches that address segmental coordination under fatigued conditions.

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Phase-Specific Analysis of Robotic-Assisted Knee Arthroplasty: Identifying Critical Learning Curves Across Three Implant Types

Harato K., Kobayashi S., Kaneda K., Matsumoto T., Niki Y.

Journal of Arthroplasty 40 ( 10 ) 2623 - 2629 2025.10

ISSN 08835403

Background: Robotic-assisted total and unicompartmental knee arthroplasties (RA-TKA, RA-UKA) are increasingly used to enhance surgical precision and improve clinical outcomes. Despite their advantages, these systems introduce a learning curve, particularly for surgeons adapting to different procedural phases. The current literature lacks detailed analyses of phase-specific contributions to the learning curve and how these differ among implant designs. This study aimed to identify critical phases within RA-TKA and RA-UKA that contributed most to operative efficiency and to propose tailored educational strategies for each device. We hypothesized that device-specific learning curves could notably impact procedural durations. Methods: A total of 204 surgeries of RA-TKAs (bicruciate retaining [BCR] and stabilized [BCS]) and RA-UKAs were done using an image-free robotic platform by three experienced surgeons. Operative time was divided into eight procedural phases. Learning curves were evaluated for each device and phase using linear regression. The slopes of the regression lines were analyzed to quantify learning effects, with statistical significance assessed for each phase. Phase-specific contributions were interpreted based on the relative steepness of significant slopes. Results: The learning curve varied across devices and phases. The BCR exhibited the steepest learning curve, particularly in phase 5 (bone resection), whereas BCS demonstrated significant improvements in phase 5 as well, but to a lesser extent. The UKA showed notable learning effects in earlier phases, particularly in phase 3 (three-dimensional model creation). These findings highlighted device-specific differences in learning effects and underscored the critical importance of phase-specific training. Conclusions: The present study identified device-specific and phase-specific differences in the learning curve for image-free robotic systems. Both BCR and BCS required focused training in later phases, such as bone resection, whereas UKA benefited from targeted improvements in earlier phases like model creation. These insights emphasized the need for tailored training protocols to optimize outcomes in robotic knee arthroplasty.

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Surgical field contamination analysis in various artificial joint arthroplasties

Oya A., Matsumura N., Fujie A., Kobayashi S., Harato K., Kaneda K., Matsumoto T., Yagi M., Suzuki T., Nakayama R., Matsumoto M., Nakamura M.

Journal of Joint Surgery and Research 3 ( 3 ) 159 - 163 2025.09

Purpose: Joint arthroplasty has shown favorable outcomes across various anatomical sites; however, complications such as peri-prosthetic joint infection (PJI) remain challenging. Despite the importance of understanding surgical field contamination, many details are unclear. This study aimed to evaluate the contamination status of the surgical field during joint arthroplasty procedures. Methods: A prospective study was conducted on 150 joint arthroplasty cases at a single institution, involving 38 men and 112 women with a mean age of 68.8 years. The cohort included 41 total shoulder arthroplasty (TSA), 31 total knee arthroplasty (TKA), and 78 total hip arthroplasty (THA) procedures. Bacterial cultures, including anaerobic cultures, were obtained from three sites: (1) the surgical scalpel immediately after skin incision; (2) the surface of the surgical tray where the instruments were placed at the end of the procedure; and (3) the hands and chest area of the surgeon's gown. Results: No early PJIs or bacterial growth was observed post-surgery. However, bacterial contamination was detected in 7 cases (4.7%), primarily in surgical trays. Cutibacterium acnes was identified in two TSA cases and one case each of TKA and THA. Other bacterial species detected included Staphylococcus hominis and Corynebacterium species. Additionally, Micrococcus luteus was found on the surgical gown of one TKA case. Contaminated cases showed significantly higher body weight (p = 0.036) and longer surgery time (p = 0.044) compared with non-contaminated cases. Conclusion: Maintaining an aseptic surgical environment, particularly in trays and gowns, is essential in preventing bacterial contamination, particularly C. acnes, during joint arthroplasty procedures.

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A Modified Arthroscopic Approach for Localized Pigmented Villonodular Synovitis in the Posterior Knee Compartment

Harato K., Kobayashi S., Matsumoto T., Kaneda K.

Arthroscopy Techniques 14 ( 7 ) 2025.07

Localized pigmented villonodular synovitis of the posterior knee compartment presents a surgical challenge due to limited arthroscopic access and the complex anatomy of the posterior knee. We describe a modified arthroscopic approach that enhances visualization and facilitates efficient resection by enlarging the posteromedial portal. This technique allows simultaneous use of the arthroscope and surgical instruments within the same portal, optimizing maneuverability and precision. The procedure involves careful portal placement, strategic use of a 70° arthroscope, and a combination of curettage, shaving, and radiofrequency ablation to achieve complete resection while minimizing iatrogenic injury. Compared to traditional approaches using both posteromedial and posterolateral portals, our method is less invasive yet provides adequate exposure for thorough lesion removal. Additionally, resection performed solely from anterior portals has been reported, but it frequently results in incomplete excision due to restricted access. This technique offers distinct advantages, including improved visualization, efficient instrument handling, and reduced operative time, making it particularly suitable for novice surgeons. By refining arthroscopic accessibility to the posterior knee compartment, this approach represents a safe, effective, and reproducible method for managing localized pigmented villonodular synovitis with minimal morbidity.

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Evaluating tibial rotation in recurrent patellar dislocation with four-dimensional computed tomography

Kaneda K., Harato K., Oki S., Morishige Y., Kobayashi S., Nakamura M., Nagura T.

Skeletal Radiology 54 ( 6 ) 1283 - 1289 2025.06

ISSN 03642348

Objective: This study is to investigate the three-dimensional (3D) kinematic changes in the knee joint in patients with recurrent patellar dislocation using four-dimensional computed tomography (4DCT) imaging and the 3D-3D surface registration technique. Materials and methods: Ten knees from nine patients with recurrent patellar dislocation and seven knees from seven controls (unaffected side of patients with unilateral anterior cruciate ligament injury) were analyzed using 4DCT. The patients were asked to extend their knees from 60° of flexion to full extension for 10 s in the CT gantry. We used the 3D-3D registration technique, and the 3D angles of the patella and tibia relative to the femur were evaluated. Results: In the dislocation group, the patellar lateral tilt increased as the knee extended. Significant differences were found between the two groups at 0°–20° of knee flexion. The tibia rotated externally as the knee extended in the dislocation group. Significant differences between the two groups were found at 0°–10° of knee flexion. Conclusion: This study demonstrated significant differences in the timing and magnitude of tibial external rotation between patients with recurrent patellar dislocation and controls. Specifically, the tibia began to externally rotate during the early phase of knee extension in the dislocation group. These findings provide new insights into knee kinematics that may inform future treatment strategies for patellar dislocation.

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Development of a wearable system to estimate knee adduction moment of patients with knee osteoarthritis during gait using a single inertial measurement unit

Akiba A., Harato K., Yoshihara H., Iwama Y., Nishizawa K., Nagura T., Nakamura M.

Journal of Joint Surgery and Research 3 ( 2 ) 84 - 89 2025.06

Purpose: The external knee adduction moment (KAM) during gait is an important mechanical factor for knee osteoarthritis (KOA). Three-dimensional motion capture (MoCap) has been used to measure KAM, but it has limitations including cost, measuring time, and space. The purpose of this study was to develop a simple and wearable system to estimate KAM. Methods: Thirty-nine female and seven male subjects diagnosed with KOA were included. Simultaneous measurements of 5 m walk using MoCap and inertial measurement unit (IMU) attached to the knee were performed, and a deep learning algorithm based on a gait phase detection algorithm and one-dimensional convolutional neural network model was used to estimate KAM. In addition, the reliability of the artificial intelligence system was also evaluated. Results: The mean absolute percent error (MAPE) and mean absolute error (MAE) of estimated KAM peak of the training data and test datasets were 13.0% and 0.0428 Nm.s/(BW∗Ht) and 17.3% and 0.0505 Nm.s/(BW∗Ht), respectively, and those of estimated KAM impulse were 20.4% and 0.0214 Nm.s/(BW∗Ht) and 21.4% and 0.0212 Nm.s/(BW∗Ht), respectively. The Pearson correlation coefficients between estimated KAM (peak, impulse) and MoCap KAM (peak, impulse) were 0.870 and 0.975 in the training dataset and 0.591 and 0.690 in the test dataset. The intraclass correlation coefficients (ICCs) of estimated KAM impulse were 0.83, 0.94, 0.70, and 0.82 for ICCs (1.1), (1,k), (2,1), and (2,k) respectively. Conclusions: The wearable system showed reasonable accuracy and reliability in estimating KAM of KOA during gait. The simple equipment in the system enables the measurement of KAM during daily practice in the clinic or hospital if there is available space to walk 5 m.

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Discrepancies in long-leg alignment and knee joint line obliquity between two- and three-dimensional measurements under weight-bearing conditions: Effects on coronal plane alignment of the knee classification

Sasaki R., Niki Y., Kaneda K., Yamada Y., Kobayashi S., Harato K., Nagura T., Nakamura M., Jinzaki M.

Knee 53 237 - 245 2025.03

ISSN 09680160

Background: Long-leg alignment and joint line obliquity have traditionally been assessed using two-dimensional (2D) radiography, but the accuracy of this measurement has remained unclear. This study aimed to evaluate the accuracy of 2D measurements of lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) using upright three-dimensional (3D) computed tomography (CT). Methods: This study involved 66 knees from 38 patients (34 women, four men) with knee osteoarthritis (OA), categorized by Kellgren–Lawrence (KL) grade. Patients underwent standing long-leg radiography (LLR) and upright CT. Flexion and rotation angles of the femur and tibia were measured from upright CT data, and knees were classified by coronal plane alignment of the knee (CPAK) according to 2D- and 3D-LDFA/MPTA. Results: Overall, as KL grade increased, femoral external rotation and flexion increased significantly (P < 0.05). Regarding the tibia, flexion increased (P < 0.05) while rotation remained unchanged with increasing KL grade. In mild OA (KL1 or KL2), 2D-LDFA (86.5 ± 1.8°) was significantly larger than 3D-LDFA (85.0 ± 2.5°; P < 0.05), and this difference was also observed in severe OA (KL3 or KL4) (88.7 ± 2.5° vs. 87.7 ± 3.2°; P < 0.05). However, MPTA was comparable between 2D and 3D. The consistency between 2D and 3D CPAK classifications was 48.5% for the entire sample, 25.0% for mild OA, and 61.9% for severe OA. Conclusion: Based on 3D-LDFA/MPTA data gained from upright CT, 2D radiographic LDFA tended to be inaccurate, which may significantly affect the CPAK classification.

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Differences in kinematics and kinetics during gait between total knee arthroplasty implant designs

Nishizawa K., Harato K., Hakukawa S., Kobayashi S., Niki Y., Nagura T.

Clinical Biomechanics 122 2025.02

ISSN 02680033

Background: Implant design is important for achieving proper knee biomechanics during gait following knee arthroplasty. Bicruciate-stabilized total knee arthroplasty attempts to replicate anterior stability and rotational facilitation. However, its detailed gait biomechanics compared with other implant designs have not been analyzed. The purpose of this study is to compare knee kinematics and kinetics between bicruciate-stabilized total knee arthroplasty, posterior-stabilized total knee arthroplasty, unicompartmental knee arthroplasty, and normal knees. Methods: Ten healthy subjects, 16 who underwent posterior stabilized total knee arthroplasty, 12 who underwent bicruciate-stabilized total knee arthroplasty, and 13 who underwent unicompartmental knee arthroplasty were recruited. The mean follow-up period after arthroplasty was 11.0 months. Three-dimensional kinematics and kinetics were assessed using a motion capture system with subjects walking on a 5-m walkway. Comparisons between groups were conducted using the Kruskal–Wallis test, and post hoc analysis was performed for those parameters that differed significantly. Findings: The bicruciate-stabilized total knee arthroplasty group showed decreased internal rotation compared to the unicompartmental knee arthroplasty group. Compared to the control group, the posterior-stabilized total knee arthroplasty group exhibited reduced knee extension and internal rotation moment. Interpretation: Bicruciate-stabilized total knee arthroplasties exhibited different biomechanical characteristics compared to unicompartmental knee arthroplasties during terminal stance. Postoperative total knee arthroplasty rehabilitation should focus on relieving stiffness owing to insufficient knee flexion-extension motion observed in both bicruciate-stabilized and posterior-stabilized total knee arthroplasties compared with unicompartmental knee arthroplasty, which may be due to a lack of knee rotational motion during gait.

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Effects of Visual Occlusion on Lower Extremity Biomechanics during a Low-Intensity Single-Leg Landing

Imai S., Harato K., Morishige Y., Nagura T., Matsumoto H., Hase K.

Journal of Human Kinetics 97 51 - 63 2025

ISSN 16405544

Visual information is crucial for motor control during a jump-landing, allowing for anticipation of landing timing and prediction of the impact. However, the effects of visual occlusion on lower extremity biomechanics are not well understood. To investigate this, we studied the impact of visual occlusion on motor control during a low-intensity single-leg landing. Seventeen female college students participated in the controlled laboratory investigation. They performed low-intensity repetitive vertical hopping on a single leg under eyes-open (EO) and eyes-closed (EC) conditions. Main outcome measurements were taken, including jump height, ground reaction forces, joint angles, and joint moments, using a motion capture system. The significant effects of visual occlusion were as follows: 1) a decrease in the hip flexion angle at ground contact (p = 0.02), 2) an increase in Fx (medio-lateral ground reaction force), knee valgus, and internal rotation angles in the early phase within 80 ms after ground contact (p < 0.05), and 3) an increase in Fz (vertical ground reaction force) and a reduction in hip and knee flexion angles at peak Fz (p < 0.05). The amount of angular change at the ankle joint correlated with the hip and knee joints only under the EC condition (p < 0.05). These changes indicate modifications in landing strategy for safety and/or deficiencies in control for an efficient and accurate landing. In conclusion, visual information contributes to safe and accurate motor control during low-intensity landing movements.

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Alteration of knee joint moment after anterior cruciate ligament reconstruction conditions in subjects with and without meniscal pathology

Nishizawa K., Harato K., Kobayashi S., Niki Y., Nagura T.

Knee 48 8 - 13 2024.06

ISSN 09680160

Background: The effects of anterior cruciate ligament (ACL) reconstruction on postoperative gait biomechanics remain controversial, and the influence of meniscus pathology on pre- and post-ACL reconstruction biomechanical changes has not yet been studied. Here, we aimed to clarify the difference in knee joint moment between pre- and post-ACL reconstruction conditions in subjects with and without meniscal pathology. Methods: Twenty-four subjects with unilateral ACL reconstruction injuries participated in this study. A total of 13 of the subjects had concomitant meniscus injuries. Gait analysis was performed preoperatively and at 11 months postoperatively. Three-dimensional knee joint angles and moments were calculated based on motion-capture data. The total joint moment and contribution of individual moments during the stance phase were assessed. For statistical analysis, we compared pre- and postoperative alterations, and differences were assessed in subjects with and without meniscal pathology. Results: Tibial rotation excursion was lower in subjects with meniscal pathology than in those with intact menisci postoperatively. An significant increase in the contribution of the knee flexion moment and a significant decrease in the contribution of the knee adduction moment postoperatively were observed in subjects with intact menisci. Conclusions: Patients with ACL injury showed different postoperative alterations in joint moments depending on the concomitant meniscal injury.

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Turning and sitting movements during timed up and go tests predict deterioration of physical function in middle-aged adults

Nishizawa K., Harato K., Hakukawa S., Okawara H., Sawada T., Ishida H., Nagura T.

Gait and Posture 108 329 - 334 2024.02

ISSN 09666362

Background: Deterioration of physical function in middle-aged adults is a significant challenge that can lead to increased risk of future falls. However, a screening method for the functional decline in middle-aged adults has not been established. Research question: To evaluate the relationship between biomechanical parameters assessed by the timed up and go test (TUG) and locomotive syndrome (LS) in middle-aged adults. Methods: The inclusion criterion was: under 65 years of age. A total of 97 volunteers (mean age 51.1 years) participated in this study. An LS test was performed, including a 2-step test, a stand-up test, and a 25-question Geriatric Locomotive Function Scale. The TUG was measured using inertial measurement units (IMUs) at comfortable and fast speeds. We then determined the minimum values for anterior-posterior acceleration and angular velocity around the medial-lateral axis, as well as the maximum values of angular velocity around the vertical axis for the upper trunk and sacrum in a TUG phase. Results: Angular velocity around the vertical axis for upper trunk and sacrum were significantly smaller in LS than non-LS in the turn phase of both speed conditions. For the fast speed condition, the minimum anterior-posterior acceleration for sacrum was greater in LS than in the non-LS condition for the stand-to-sit phase. Angular velocity around the vertical axis for turning and anterior-posterior acceleration from sitting were associated with detection of LS. Significance: Turning and sitting movements during TUG should be observed using IMU to screen for physical function decline in middle aged adults.

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The Stat3 inhibitor F0648-0027 is a potential therapeutic against rheumatoid arthritis

Kaneko Y., Ozawa S.i., Sato Y., Kobayashi T., Matsumoto T., Miyamoto K., Kobayashi S., Harato K., Hirono S., Matsumoto M., Nakamura M., Niki Y., Miyamoto T.

Biochemical and Biophysical Research Communications 636 133 - 140 2022.12

ISSN 0006291X

Rheumatoid arthritis (RA) is a disease characterized by chronic joint inflammation, pain and joint destruction, leading to alteration in activities of daily living, yet pathological mechanisms underlying the condition are not fully clarified. To date, various therapeutic agents have been developed as RA therapy including DMARDs and/or biological agents that target inflammatory cytokines or inhibit JAK. Here we asked whether inhibiting signal transducer and activator of transcription 3 (Stat3) activity would antagonize RA. Stat3 forms dimers when activated and undergoes nuclear translocalization; thus we screened approximately 4.9 million small compounds as potential blockers of protein-protein interactions required for Stat3 dimerization using in silico screening. We identified 15 as strong candidates as potential blockers of protein-protein interactions required for Stat3 dimerization using in silico screening from those compounds. Four of the 15 significantly inhibited expression of IL-6 and RANKL, both of which are direct targets of Stat3, induced by IL-6. Among four, one compound, F0648-0027, significantly inhibited arthritis development without apparent adverse effects in vivo in collagen-induced arthritis model mice. F0648-0027 also significantly blocked Stat3 phosphorylation and nuclear localization following IL-6 stimulation of fibroblasts. These data suggest that Stat3 is a target for collagen-induced arthritis in mice, and that F0648-0027 could serve as a therapeutic reagent against comparable conditions in humans.

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Pain detect questionnaire and pain catastrophizing scale affect gait pattern in patients with knee osteoarthritis

Harato K., Iwama Y., Kaneda K., Kobayashi S., Niki Y., Nagura T.

Journal of Experimental Orthopaedics 9 ( 1 ) 2022.12

Purpose: Although pain phenotype affects clinical score in patients with knee osteoarthritis (OA), little information has been available on the relationship between pain phenotype and gait analysis. The purpose was to investigate the relationship between pain phenotype and gait parameters. Methods: A total of 34 patients (24 females and 10 males) with end-stage medial compartmental knee OA participated. All the patients were evaluated based on pain detect questionnaire (PD-Q) and pain catastrophizing scale (PCS). They were divided into two categories: Group Low (PD-Q score ≤ 12) and Group High (PD-Q score > 12), PCS + (PCS ≥ 23) and PCS- (PCS < 23). Gait analysis was performed using three-dimensional motion analysis system. Statistical analysis was done to compare gait parameters between groups for each allocation of PD-Q or PCS, separately. Results: Peak vertical ground reaction forces in Group Low and High were 0.99 ± 0.054 and 0.82 ± 0.17, respectively (P = 0.015). Peak knee adduction moments in Group Low and High were 0.70 ± 0.19 and 0.39 ± 0.14, respectively (P = 0.0022). For PCS allocation, knee extension limitation during mid-stance during gait were significantly larger in PCS- (P = 0.038). Conclusions: Patients with high PD-Q score had atypical gait pattern with smaller peak vertical ground reaction force and knee adduction moment, compared to patients with low PD-Q score. Moreover, patient with low PCS had different gait pattern in extension limitation, compared to those with high PCS. PD-Q and PCS would affect gait pattern in patients with knee OA. Level of evidence: III.

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Effects of foot progression angle on kinematics and kinetics of a cutting movement

Nishizawa K., Hashimoto T., Hakukawa S., Nagura T., Otani T., Harato K.

Journal of Experimental Orthopaedics 9 ( 1 ) 2022.12

Purpose: Foot progression angle is a key factor for biomechanical knee load, which is associated with noncontact anterior cruciate ligament (ACL) injury during sports-specific tasks. The purpose of the present study was to assess the biomechanics of trunk, pelvis, and lower extremities during a cutting maneuver under different foot progression angles. Methods: Nineteen male collegiate athletes (ages 18–24) participated in the present study. Cutting motion was analyzed using eight infrared cameras (250 Hz), two force plates (1250 Hz), and 44 reflective markers. Subjects performed 45-degree side cutting maneuvers under three foot progression angles, including 20 degrees (toe-out: TO), 0 degrees (neutral: TN), and − 20 degrees (toe-in: TI). Peak values of each biomechanical parameters in trunk, pelvis, hip, and knee within a first 40% stance phase and each parameter at the timing of the peak vertical ground reaction force were assessed. A statistical analysis was performed to compare data among the three-foot progression angles using the Friedman test. Results: Peak angles of knee abduction, tibial internal rotation, hip internal rotation, and hip adduction were significantly greater for TI position than for TO position (p < 0.01). Peak moments of knee abduction and tibial internal rotation under TI position were also significantly larger than TO position (p < 0.01). Moreover, greater peak pelvis-trunk rotation was found for TI position than for TN and TO positions (p < 0.01). Conclusion: From the present study, TI position could lead to an increased risk of ACL injury during a pre-planned cut maneuver, compared to TO position.

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Biomechanical features of drop vertical jump are different among various sporting activities

Harato K., Morishige Y., Kobayashi S., Niki Y., Nagura T.

BMC Musculoskeletal Disorders 23 ( 1 ) 2022.12

Background: Risk for non-contact anterior cruciate ligament (ACL) injury can be assessed based on drop vertical jump (DVJ). However, biomechanics of DVJ may differ with various sporting activities. The purpose of the present study was to clarify whether biomechanical features of DVJ are different among various sporting activities in female athletes. Methods: A total of 42 female athletes, including 25 basketball, 8 soccer and 9 volleyball players, participated in the current investigation. DVJ was done for each female athlete using a three-dimensional motion analysis system which consisted of six cameras, two force plates and 46 retro-reflective markers. Kinematic and kinetic data were recorded for both limbs in each athlete. Simultaneously, frontal and sagittal plane views of the DVJ were recorded using two different high-resolution video cameras to evaluate Landing Error Scoring System (LESS) score. Three-dimensional biomechanical parameters at the knee joint and LESS were compared among three different sporting activities using ANOVA or Kruskal–Wallis test after confirming normality assumption. Thereafter post hoc Tukey or Steel–Dwass was utilized for multiple comparison. Results: Soccer players had better LESS score, and peak knee flexion angle was significantly larger in soccer players compared to the other sports. In addition, knee abduction angle at initial contact (IC), peak knee abduction angle, knee internal rotation angle, and knee abduction moment within 40 ms from IC were significantly smaller in soccer players, compared to basketball players. In terms of volleyball players, knee abduction angle at IC and knee internal rotation angle at IC were significantly larger than soccer players, whereas no significant biomechanical differences were found between basketball and volleyball players. Conclusions: From the present study, female basketball and volleyball players have worse LESS score, smaller peak knee flexion angle, greater knee abduction angle at IC and greater knee internal rotation angle at IC, compared to female soccer players. Thus, female basketball and volleyball players may have an increased risk of non-contact ACL injury during the jump-landing task, compared to soccer players. Biomechanics of DVJ depends on characteristics of the athlete's primary sport.

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Increase in tibial internal rotation due to weight-bearing is a key feature to diagnose early-stage knee osteoarthritis: a study with upright computed tomography

Kaneda K., Harato K., Oki S., Yamada Y., Nakamura M., Nagura T., Jinzaki M.

BMC Musculoskeletal Disorders 23 ( 1 ) 2022.12

Background: The classification of knee osteoarthritis is an essential clinical issue, particularly in terms of diagnosing early knee osteoarthritis. However, the evaluation of three-dimensional limb alignment on two-dimensional radiographs is limited. This study evaluated the three-dimensional changes induced by weight-bearing in the alignments of lower limbs at various stages of knee osteoarthritis. Methods: Forty five knees of 25 patients (69.9 ± 8.9 years) with knee OA were examined in the study. CT images of the entire leg were obtained in the supine and standing positions using conventional CT and 320-row detector upright CT, respectively. Next, the differences in the three-dimensional alignment of the entire leg in the supine and standing positions were obtained using 3D-3D surface registration technique, and those were compared for each Kellgren–Lawrence grade. Results: Greater flexion, adduction, and tibial internal rotation were observed in the standing position, as opposed to the supine position. Kellgren–Lawrence grades 1 and 4 showed significant differences in flexion, adduction, and tibial internal rotation between two postures. Grades 2 and 4 showed significant differences in adduction, while grades 1 and 2, and 1 and 3 showed significant differences in tibial internal rotation between standing and supine positions. Conclusions: Weight-bearing makes greater the three-dimensional deformities in knees with osteoarthritis. Particularly, greater tibial internal rotation was observed in patients with grades 2 and 3 compared to those with grade 1. The greater tibial internal rotation due to weight-bearing is a key pathologic feature to detect early osteoarthritic change in knees undergoing osteoarthritis.

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Knee varus alters three-dimensional ankle alignment in standing- a study with upright computed tomography

Hakukawa S., Kaneda K., Oki S., Harato K., Yamada Y., Niki Y., Nagura T., Nakamura M., Jinzaki M.

BMC Musculoskeletal Disorders 23 ( 1 ) 2022.12

Background: For knee osteoarthritis (OA) treatment, it is important to correct the lower limb alignment including the foot. However, in the upright position, lower limb alignment is generally assessed from the body surface or radiographs, and it is a challenge to capture the exact characteristics of three-dimensional lower limb alignment. The purpose of the study was to measure lower limb alignment in patients with knee OA using upright computed tomography (CT) and radiography, and to identify features of knee joint deformity. Methods: A total of 45 limbs in 25 patients with knee OA were enrolled. The subjects underwent both upright CT and radiography for the whole lower limb in the standing position. The joint angles were calculated on both images. The degree of knee OA was classified according to Kellgren-Lawrence (KL) grade by referring to radiography, which is mainly based on the degree of articular cartilage loss and severity of osteophytes, and the characteristics or correlation between knee and ankle joint in each group was investigated. Results: In KL-I, there was an association between varus of the knee joint and internal rotation of the talocrural joint (r = 0.76, P < 0.05). In KL-II, there was an association between varus of the knee joint and eversion of the subtalar joint (r = 0.63, P < 0.05) and talocrural joint (r = − 0.65, P < 0.05). In KL-III, there was an association between varus of the knee joint and internal rotation of the subtalar joint (r = − 0.62, P < 0.05), and in KL-IV, there was an association between varus of the knee joint and internal rotation of the subtalar joint (r = − 0.58, P < 0.05). Conclusions: The lower limb alignment of patients with knee OA in the standing position was found that as knee OA worsened, it became apparent that compensatory knee joint alignment depended on the ankle joint rather than the subtalar joint. The results may help in the rehabilitation of patients with knee OA, since the ankle joint alignment has a significant impact on the knee joint during coarse movements involving load.

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Goals, challenges and strategies for wound and bleeding management in total knee arthroplasty: A modified Delphi method

Lyons M., Nunley R.M., Ahmed Shokri A., Doneley T., Han H.S., Harato K., Kuwasawa A., Lee D.H., Qi X., Qian W., Ratanachai S., Wang W., Po-Han Chen B., Danker W.

Journal of Orthopaedic Surgery 30 ( 3 ) 2022.09

ISSN 10225536

Background: Surgical techniques related to soft tissue management play critical roles in optimizing surgical outcomes and patient satisfaction in total knee arthroplasty (TKA). Despite the importance of wound closure and bleeding management approaches, no published guidelines/consensus are available. Methods: Twelve orthopedic surgeons participated in a modified Delphi panel consisting of 2 parts (each part comprising two rounds) from September–October 2018. Questionnaires were developed based on published evidence and guidelines on surgical techniques/materials. Questionnaires were administered via email (Round 1) or at a face-to-face meeting (subsequent rounds). Panelists ranked their agreement with each statement on a five-point Likert scale. Consensus was achieved if ≥70% of panelists selected 4/5, or 1/2. Statements not reaching consensus in Round 1 were discussed and repeated or modified in Round 2. Statements not reaching consensus in Round 2 were excluded from the final consensus framework. Results: Consensus was reached on 13 goals of wound management. Panelists agreed on 38 challenges and 71 strategies addressing surgical techniques or wound closure materials for each tissue layer, and management strategies for blood loss reduction or deep vein thrombosis prophylaxis in TKA. Statements on closure of capsular and skin layers, wound irrigation, dressings and drains required repeat voting or modification to reach consensus. Conclusion: Consensus from Asia-Pacific TKA experts highlights the importance of wound management in optimizing TKA outcomes. The consensus framework provides a basis for future research, guidance to reduce variability in patient outcomes, and can help inform recommendations for wound management in TKA.

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Four-dimensional computed tomographic analysis of screw home movement in patients with anterior cruciate ligament deficient knee — a 3D-3D registration technique

Morishige Y., Harato K., Oki S., Kaneda K., Niki Y., Nakamura M., Nagura T.

Skeletal Radiology 51 ( 8 ) 1679 - 1685 2022.08

ISSN 03642348

Objective: The tibia externally rotates to the femur during the last 20° of the knee extension motion. This kinematic phenomenon is well known as screw home movement (SHM). The purpose was to clarify the SHM in anterior cruciate ligament deficient (ACLD) knee using four-dimensional computed tomography (4DCT). Materials and methods: Six patients with a unilateral isolated ACLD knee participated. In the static position, CT scan of the both limbs of the femur and tibia were performed. Then, 4DCT was performed around knee. In the CT gantry, subjects were positioned in supine position with 45° of knee flexion on a triangle pillow and were asked to extend the knee to full extension within 10 s on each limb. The CT data were accumulated in digital imaging and communication in medicine (DICOM) data format. From the static CT and 4DCT DICOM data, three-dimensional surfaces of the knee joint were reconstructed. The whole tibia surface was matched into the partial tibia surface of that frame using 3D-3D registration technique. After the assessment of coordination system of the whole leg, knee flexion, abduction, and external rotation angle were calculated. Results: Knee external rotation angle was significantly smaller on the ACLD side than on the contralateral unaffected side in 0–15° of knee flexion (P < 0.05 in 0, 5, 10, and 15 degrees), while the angle was similar during 15–60° of knee flexion. Conclusion: The absence of SHM in ACLD knee was detected using 3D-3D registration technique based on 4DCT.

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Application of an indentation sensor for the arthroscopic measurement of articular cartilage stiffness

Kitta Y., Kiriyama Y., Harato K., Kobayashi S., Niki Y., Matsumoto M., Nakamura M., Nagura T.

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine 236 ( 4 ) 566 - 572 2022.04

ISSN 09544119

Direct measurement of cartilage stiffness provides useful clinical information and enables us to develop treatment strategies for patients. We applied an indentation sensor to evaluate cartilage stiffness under arthroscopic control. The purpose of this study was to validate the arthroscopic indentation sensor using cadaver knees and to measure cartilage stiffness in clinical cases. The stiffness of a material with known properties was measured at thicknesses from 2 mm to 10 mm with a 2-mm interval. This was repeated three times at each thickness to evaluate repeatability. The articular cartilage stiffness of the medial and lateral femoral condyles of five human cadaveric knees was measured. The sensor was inclined from 0° to 20° with 1° intervals. The stiffness value at each degree of inclination was compared to evaluate the acceptable measuring angle. Additionally, articular cartilage stiffness was measured in 23 adolescent and 11 adult patients under arthroscopy. Young’s moduli of the material were 1.15–1.24 (mean 1.20) MPa. Inter-class correlation coefficients in repeated measurements using the material were 0.83–0.99. There were no differences in the cartilage stiffness between the medial and lateral femoral condyles of the cadaver knees. All condyles showed a nonlinear relationship between force and displacement. The force decreased in all condyles when the tip of the sensor system was tilted. The range of error was < 97.1% within 5° inclination. There was a moderate negative correlation between age and cartilage stiffness in adolescent patients, and a moderate positive correlation in adult patients. Since the sensor system is manually held during measurement, the validity and repeatability to assess material properties of the cartilage may be inaccurate. This study has proven that the instrument can measure the stiffness of joint cartilage reliably and is a useful clinical tool under arthroscopic control.

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