二木 康夫

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。

症例1は66歳女性で、63歳時より第2、3趾にも変形が生じ、足底痛、第2、3趾背側痛が出現した。その後疼痛が増強したため手術目的で当科を受診した。第2、3趾にハンマー趾変形と第2・3中足趾節(MTP)関節背側完全脱臼を伴う重度外反母趾と診断し、手術を行った。第2・3中足骨長に合わせて母趾中足骨の短縮量を調整するように第1中足骨遠位直線状骨切り術(DLMO)変法を施行した。術後1年6ヵ月で、母趾は第2趾に比べやや長いものの、外反母趾(HV)角は2°、第1・2中足骨間(M1M2)角は9°、日本足の外科学会(JSSF)スケールは90点と術後経過は良好であった。症例2は58歳女性で、右外反母趾と第2から第5趾のMTP関節背側脱臼を認めた。第2から5趾のMTP関節背側脱臼を伴う重度外反母趾と診断し、症例1と同様にDLMO変法を行った。術後1年1ヵ月で、HV角は17°、M1M2角は10°、JSSFスケールは95点と術後成績は良好であった。

© 2018, The Author(s). Auto-inflammatory syndrome, a condition clinically distinct from rheumatoid arthritis, is characterized by systemic inflammation in tissues such as major joints, skin, and internal organs. Autonomous innate-immune activation is thought to promote this inflammation, but underlying pathological mechanisms have not been clarified nor are treatment strategies established. Here, we newly established a mouse model in which IL-1 signaling is conditionally activated in adult mice (hIL-1 cTg) and observed phenotypes similar to those seen in auto-inflammatory syndrome patients. In serum of hIL-1 cTg mice, IL-6 and IL-17 levels significantly increased, and signal transducer and activator of transcription 3 (Stat3) was activated in joints. When we crossed hIL-1 cTg with either IL-6- or IL-17-deficient mice or with Stat3 conditional knockout mice, phenotypes seen in hIL-1 cTg mice were significantly ameliorated. Thus, IL-6, IL-17 and Stat3 all represent potential therapeutic targets for this syndrome.

Axial loading of the human cadaver lower leg is known to generate eversion of the calcaneus and internal rotation of the tibia if the plantar surface of the foot does not slide on the floor. Such kinematic coupling between calcaneal eversion and internal tibial rotation has been described previously, but no studies have actually quantified the innate ability of the human foot to generate ground reaction moment around the vertical axis of the floor (vertical free moment) due to axial loading of the human cadaver lower leg. This study investigated the vertical free moment generated by eight cadaveric lower leg specimens loaded vertically with traction of the Achilles’ tendon using a six-component force plate. The vertical free moments in all specimens were oriented toward the direction of internal rotation, and the mean magnitude of the vertical free moments was −1.66 N m when an axial load of 450 N was applied. A relatively large ground reaction moment can be applied to the body during walking due to the innate structural mobility of the foot. The structurally embedded capacity of the human foot to generate the vertical free moment may facilitate compensation of the moment generated around the vertical axis of the body during walking due to trunk rotation and leg swing.