セラミック人工膝関節の動作解析

機関リポジトリ

書誌事項

タイトル別名
  • Motion Analysis of Ceramic Total Knee Arthroplasty
  • セラミック ジンコウ シツカンセツ ノ ドウサ カイセキ

この論文をさがす

抄録

type:原著

【目的】日本メディカルマテリアル(JMM)社セラミック製のLFA 人工膝関節を使用した膝関節置換術(LFA- total knee arthroplasty 以下LFA-TKA)を行い,膝関節屈伸時の人工関節動態と膝関節周囲軟部組織の弛緩性との関連を明らかにすることを目的とした.【対象と方法】対象はLFA-TKA を行い協力の得られた31 例39 膝であり,これらのうち27 例33 膝では後十字靭帯温存型(CR 型)が用いられ,4 例6 膝では後十字靭帯代償型(PS 型)が用いられていた.原疾患は,変形性膝関節症でCR 型30 膝,PS 型4 膝,リウマチ性関節炎でCR 型3 膝,PS 型2 膝であった.術後の膝関節動態解析にはデジタルフルオロスコープを用いて,荷重下の膝屈曲位から立位までの動作を膝側面から撮像した.得られた画像データを運動解析ソフトKnee Motion(R) を用いて膝伸展位を起点として解析し,脛骨インサートに対する大腿骨コンポーネントの内側顆,外側顆の接触点の移動から,1)大腿骨のロールバック,2)脛骨長軸方向の回旋パターン,3)pivot 中心位置を解析した.次いで膝内外反と前後方ストレス撮影を行い,内外反角と前後方移動量を計測し動態パターンとの関連を検討した.【結果】1) 大腿骨コンポーネントのロールバックは,CR 型では一定の傾向は認めず関節周囲軟部組織の弛緩性との関連も見いだせなかった.PS 型では内外側顆とも移動距離(平均±標準偏差)は内側9.6±2.6 mm,外側13.5±8.2 mm と,膝屈曲100°以上で有意なロールバックを認めた.2) 脛骨長軸方向の回旋パターンに関しては,CR 型で,外旋48%,内旋52%,PS 型では外旋33%,内旋67%で,一定の傾向は確認されなかった.3) Pivot 中心の位置はCR 型でmedial pivot27%,lateral pivot42%,その他31%,PS 型でmedial pivot67%,lateral pivot33%,その他33%と,大きな個人間差異を認め,一定の傾向は認めなかった.ストレス撮影では,内外反角は有意にCR 型が大きく,前後方移動量はCR 型とPS 型は同等であったが,膝周囲軟部組織の弛緩性と人工膝関節動態との間に明確な関連は見いだせなかった.【考察】変形性膝関節症やリウマチ性関節炎では,手術前から正常の動態を示さない症例が少なくない.人工関節膝置換術ではさらに前十字靱帯を切除しなければならないため,膝周囲軟部組織のバランスは,症例毎に一様ではない.人工膝関節動態がインプラントデザイン以外の要因によって大きく影響をうけている可能性が示唆された.【結語】LFA-TKA のPS 型では大腿骨コンポーネントのロールバックを確認できたが,PS 型とCR 型ともに術後の膝関節動態には個々の差が大きく正常膝の関節動態は再現されていなかった.また,膝周囲軟部組織の弛緩性との明確な関連は見いだせなかった.

PurposeThe purpose of this study was to clarify the relationship between the laxity of surrounding soft tissue and artificial joint kinetics during knee articulation, where total knee arthroplasty had been performed using ceramic LFA artificial knee joints( LFA-TKA below) from Japan Medical Materials(JMM).Materials & MethodsThe subjects of the study were 39 knees in 31 LFATKA recipients whose cooperation could be obtained. The CR type joint (posterior cruciate retention design) was used in 33 knees in 27 recipients and the PS type joint (posterior cruciate stabilizer design) was used in 6 knees in 4 recipients. OA patients received 30 CR type and 4 PS type joints while RA patients received 3 CR type and 2 PS type joints. For analysis of post surgery knee joint kinetics, using digital fluoroscopy, lateral images were taken of knee motion from a loaded squat position to the erect standing position. Using Knee Motion(R) software the imaging data was evaluated for 1) femoral rollback, 2) tibial axial rotationpatterns, and 3) pivot center position, from analysis of lateral and medial condylar translation (femoral components) at the point of contact with the tibial insert, starting from the extended position. Subsequent imaging under medial- lateral and posteroanterior stress was performed to measure the medial-lateral dihedral angle changes and posteroanterior movement, and the relationship of those factors to the dynamic patterns was evaluated.Results1) No definite tendency was noted in Rollback of the CR type femoral components and no relationship to the laxity of surrounding soft tissue was found. For PS type joints both medial and lateral movement (average±standard deviation) was 9.6±2.6 mm and 13.5±8.2 mm respectively so that significant rollback was noted when flexed past 100 °.2) As for tibial axial rotation patterns, of CR type joints 48 % rotated outward and 52 % rotated inward while of the PS type joints 33 % rotated outward and 67 % rotated inward, such that no definite tendency was determined. 3) As for the pivot center, among CR type joints 27 % were medial, 42 % were lateral and 33 % were other, and among PS type joints 67 % were medial, 33 % lateral and 33 % other, with large individual differences but no definite tendency. Stress imaging showed significantly greater medial-lateral dihedral angles for CR type joints, and equal posteroanterior movement for both CR and PS joints, but no clear relationship was found between the laxity of surrounding soft tissue and the kinetics of artificial knee joints.DiscussionKnees with degenerative and rheumatoid arthritis that do not exhibit normal kinetics prior to surgery are not uncommon. Then since the ACL must be sacrificed in the TKA process, knee area soft tissue balance is not uniform between cases. The possibility is suggested that artificial knee joint kinetics are influenced more significantly by factors other than the design of the implant.ConclusionWhile rollback was verified with PS type LFA-TKA, there were such large individual differences for both PS and CR cases that normal knee kinetics were not reproducible. Also, no clear relationship to knee area soft tissue was found.

identifier:19

identifier:KJ00009214775

収録刊行物

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ