二木 康夫

Purpose The full‐body kinematic chain plays a crucial role in golf swings, and trunk muscle fatigue may significantly affect swing mechanics. This study aimed to investigate how trunk muscle fatigue influences trunk and lower limb kinematics during golf swings. Methods Eleven healthy adult golfers (mean age: 20.3 ± 0.8 years) participated in a pre–post experimental study conducted in a biomechanics laboratory with a grass‐simulated hitting surface. Participants performed golf swings with a 7‐iron before and after undergoing a trunk muscle fatigue protocol involving plank exercises. Three‐dimensional kinematic data of the trunk and lead‐side lower limbs were recorded. Results Following the fatigue protocol, trunk sagittal plane stability significantly decreased (pre: 47.9°, post: 43.4°, p   < 0.01). Ankle range of motion also declined in both the sagittal plane (34.5° to 30.0°, p   < 0.05) and frontal plane (15.8° to 12.3°, p   < 0.01). Although total lower limb joint moments remained unchanged, the relative contribution of frontal‐plane ankle moments significantly decreased (15.6% 12.6%, p   < 0.05). Conclusion Trunk muscle fatigue reduces trunk stability and ankle mobility during golf swings. Increased lower limb stiffness may act as a compensatory strategy to maintain swing mechanics under fatigued conditions.

PURPOSE: Graft-notch impingement and large graft bending angle (GBA) in anterior cruciate ligament reconstruction (ACLR) carry a risk of graft failure and subsequent poor postoperative outcomes. Most studies have analyzed the impingement rate and GBA using computed tomography (CT) in the supine position, but not in the standing condition. This study aimed to assess the graft impingement and GBA using upright multi-detector CT (MDCT). METHODS: We analyzed 43 knee joints of 23 healthy volunteers (women, n = 13; men, n = 10) in a single-leg standing position using an upright 320-detector-row CT. We defined the putative position of the graft tunnel in three-dimensional models and assessed the impingement rate and GBA of both the anteromedial (AMB) and posterolateral bundles (PLB). RESULT: The impingement rate for the AMB with a 6-mm graft diameter (81.4 %) was significantly higher than that for the PLB (0.7 %; P < 0.001). The modified AMB tunnel position, which connects the midpoint between the traditional AM and PL tunnel apertures of the femur to the most medial point within the tibial AM footprint, reduced the impingement rate by 14.0 % (P < 0.001). The impingement rate of the modified AMB with a 10-mm graft diameter (32.6 %) was significantly lower than that of the traditional AMB with a 6-mm graft diameter (81.4 %; P < 0.001). The GBA of the modified AMB was significantly smaller than that of the traditional AMB (P < 0.001). CONCLUSION: This study indicated high graft-notch impingement rates and large GBA for traditional AMB in the standing position, highlighting potential biomechanical challenges associated with traditional double-bundle ACLR configurations.

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.

BACKGROUND: The traditional anteroposterior (AP) axis (i.e., Akagi's line) has been widely used as the tibial component AP axis during total knee arthroplasty (TKA). However, this AP axis has been defined based on computed tomography (CT) in a non-weight-bearing supine position. In this study, AP axes of the tibial plateau from upright CT in weight-bearing and non-weight-bearing positions were determined and compared. METHODS: This study included 43 knees from 23 healthy volunteers. CT images were obtained in weight-bearing and non-weight-bearing standing positions using a 320-detector row upright CT scanner. The line perpendicular to surgical transepicondylar axis projected onto the tibia plateau was determined as the AP axis in upright weight-bearing and non-weight-bearing conditions. Angular differences between these two conditions were measured. RESULTS: The upright weight-bearing AP axis was positioned in a mean of 7.4 ± 4.3° of internal rotation relative to the traditional AP axis. Distance between the traditional and upright weight-bearing AP axis was 2.9 ± 1.6 mm at the edge of the tibial plateau. The upright non-weight-bearing AP axis was positioned in a mean of 3.5 ± 4.1° of internal rotation relative to the traditional AP axis. Mean angular difference between weight-bearing and non-weight-bearing conditions was 3.9 ± 4.1°. CONCLUSIONS: The upright weight-bearing AP axis was positioned in 7.4° of internal rotation relative to the traditional AP axis, showing one-seventh of the tibial tuberosity away from the medial border of the tibial tubercle, which represents a practical landmark for the tibial component AP axis during TKA.

BACKGROUND: Although various reconstruction techniques are available for anterior cruciate ligament (ACL) injuries, a long recovery time is required before patients return to sports activities, as the reconstructed ACL requires time to regain strength. To date, several studies have reported use of mesenchymal stem cells in orthopaedic surgery; however, no studies have used adipose-derived stem cell (ADSC) sheets in ACL reconstruction (ACLR). HYPOTHESIS: ADSC sheet transplantation can improve biomechanical strength of the autograft used in ACLR. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 68 healthy Japanese white rabbits underwent unilateral ACLR with a semitendinosus tendon autograft after random enrollment into a control group (no sheet; n = 34) and a sheet group (ADSC sheet; n = 34). At 2, 4, 8, 16, and 24 weeks after surgery, rabbits in each group were sacrificed to evaluate tendon-bone healing using histological staining, micro-computed tomography, and biomechanical testing. At 24 weeks, scanning transmission electron microscopy of the graft midsubstance was performed. RESULTS: The ultimate failure load for the control and sheet groups, respectively, was as follows: 17.2 ± 5.5 versus 37.3 ± 10.3 (P = .01) at 2 weeks, 28.6 ± 1.9 versus 47.4 ± 10.4 (P = .003) at 4 weeks, 53.0 ± 14.3 versus 48.1 ± 9.3 (P = .59) at 8 weeks, 66.2 ± 9.3 versus 95.2 ± 43.1 (P = .24) at 16 weeks, and 66.7 ± 27.3 versus 85.3 ± 29.5 (P = .39) at 24 weeks. The histological score was also significantly higher in the sheet group compared with the control group at early stages up to 8 weeks. On micro-computed tomography, relative to the control group, the bone tunnel area was significantly narrower in the sheet group at 4 weeks, and the bone volume/tissue volume of the tendon-bone interface was significantly greater at 24 weeks. Scanning transmission electron microscopy at 24 weeks indicated that the mean collagen fiber diameter in the midsubstance was significantly greater, as was the occupation ratio of collagen fibers per field of view, in the sheet group. CONCLUSION: ADSC sheets improved biomechanical strength, prevented bone tunnel enlargement, and promoted tendon-bone interface healing and graft midsubstance healing in an in vivo rabbit model. CLINICAL RELEVANCE: ADSC sheets may be useful for early tendon-bone healing and graft maturation in ACLR.

48歳男性。26歳頃より両側反張膝が出現し、徐々に歩行障害を認めたため当院へ紹介となった。筋力低下の精査目的で神経伝導検査を行ったところ、上下肢に均一な伝導速度低下や遠位潜時延長が認められ、本症例はポリニューロパチーに併発した後天性両側反張膝と診断された。理学療法等の保存的治療が行われるも改善せず、両側hinge型人工膝関節置換術が施行された。その結果、術後2日目より膝装具を装着して歩行開始し、術後4週で軽介助により700m以上の杖歩行が可能となった。術後6ヵ月経過現在、関節可動域は右膝伸展が20°から0°、左膝伸展が25°から0°へ、JOAスコアは50点から70点へ改善した。

Auto-inflammatory syndromes are rare diseases characterized by arthritis and joint destruction, symptoms similar to but distinct from rheumatoid arthritis (RA). Therapeutic targets have not been well characterized for auto-inflammatory syndromes, although the E3 ligase Synoviolin was previously shown to be a novel therapeutic target for RA. Here, we show that Synoviolin loss has little impact on a model of auto-inflammatory diseases. We previously established such a model, the hIL-1 cTg mouse, in which IL-1 signaling was constitutively activated, and animals exhibit symptoms recapitulating auto-inflammatory syndromes such as major joint dominant arthritis. Here, we crossed hIL-1 cTg with Synoviolin flox'd mice to yield hIL-1 cTg/Synoviolin cKO mice. Synoviolin gene expression was ablated in adult hIL-1 cTg/Synoviolin cKO mice by injection of pIpC to activate Mx1 promoter-driven Cre recombinase. However, symptoms seen in hIL-1 cTg mice such as arthritis and joint destruction were not alleviated by targeting Synoviolin, ruling out Synoviolin as a therapeutic target for auto-inflammatory disease. Our results indicate that although similar, RA and auto-inflammatory diseases are different diseases, and treatment strategies should differ accordingly.

11歳4ヵ月女児。誘因なく両足関節部痛が出現、その後は2週間、同部位の腫脹が持続したため近医を受診し、単純X線で脛骨遠位骨幹端部の透亮像を指摘され、当科へ紹介となった。初診時、既に疼痛は軽減し、身体所見や検査所見上、化膿性骨髄炎や腫瘍性疾患の可能性は低いと考え、足関節軟性装具を処方して経過観察とした。しかし、整形外科以外の疾患も考え小児科を受診し、慢性再発性多発性骨髄炎(CRMO)を疑い、生検組織病理像や臨床症状、画像所見からCRMOと診断された。生検後3ヵ月目に再度左足関節部に疼痛が出現したが、NSAIDsの服用を行ったところ疼痛は軽減した。生検術後から2年の最終観察時には疼痛は消失し、目下は元の活動レベルに復帰している。

51歳女性。20歳台より両側母趾外反変形と疼痛を自覚、有効な治療法はないと言われ放置していたが、今回、疼痛が増悪したため当科を初診、症状の強い左側に対する手術目的で入院となった。画像所見を踏まえて、第1中足骨に著明な回旋変形を伴った重度外反母趾と診断され、3D-CT所見を参考に第1中足骨近位骨切り術を施行した。本症例では術前round徴候が陽性で、DMA角は55°と極めて大きかったが、3D-CTにて内側から描出された第1中足骨頭の形状が正常な単純X線底屈側でみられる形状と類似していたことから、第1中足骨がほぼ90°回内していることが想定できた。そこで、Mann変法を行った際に遠位骨片を110°回外させた結果、第1MTP関節の良好な適合性を得ることができた。目下、術後3年経過で母趾MTP関節の可動域は底屈0°、背屈20°と制限がみられるものの母趾のアライメントは良好で、疼痛は認められていない。