2016年8月
No condylar lift-off occurs because of excessive lateral soft tissue laxity in neutrally aligned total knee arthroplasty: a computer simulation study
KNEE SURGERY SPORTS TRAUMATOLOGY ARTHROSCOPY
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- 巻
- 24
- 号
- 8
- 開始ページ
- 2517
- 終了ページ
- 2524
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1007/s00167-015-3687-4
- 出版者・発行元
- SPRINGER
Condylar lift-off can induce excessive polyethylene wear after total knee arthroplasty (TKA). A computer simulation was used to evaluate the influence of femoral varus alignment and lateral collateral ligament (LCL) laxity on lift-off after single-design TKA. It was hypothesised that proper ligament balancing and coronal alignment would prevent lift-off.
The computer model in this study is a dynamic musculoskeletal program that simulates gait up to 60A degrees of knee flexion. The lift-off phenomenon was defined as positive with an intercomponent distance of > 2 mm. In neutrally aligned components in the coronal plane, the femoral and tibial components were set perpendicular to the femoral and tibial mechanical axis, respectively. The femoral coronal alignment was changed from neutral to 5A degrees varus in 1A degrees increments. Simultaneously, the LCL length was elongated from 0 to 5 mm in 1-mm increments to provide a model of pathological slack.
Within 2A degrees of femoral varus alignment, lift-off did not occur even if the LCL was elongated by up to 5 mm. However, lift-off occurred easily in the stance phase in femoral varus alignments of > 3A degrees with slight LCL slack. The contact forces of the tibiofemoral joint were influenced more by femoral varus alignment than by LCL laxity.
Aiming for neutral alignment in severely varus knees makes it difficult to achieve appropriate ligament balance. Our study suggests that no lift-off occurs with excessive LCL laxity alone in a neutrally aligned TKA and therefore that varus alignment should be avoided to decrease lift-off after TKA.
Case series, Level IV.
The computer model in this study is a dynamic musculoskeletal program that simulates gait up to 60A degrees of knee flexion. The lift-off phenomenon was defined as positive with an intercomponent distance of > 2 mm. In neutrally aligned components in the coronal plane, the femoral and tibial components were set perpendicular to the femoral and tibial mechanical axis, respectively. The femoral coronal alignment was changed from neutral to 5A degrees varus in 1A degrees increments. Simultaneously, the LCL length was elongated from 0 to 5 mm in 1-mm increments to provide a model of pathological slack.
Within 2A degrees of femoral varus alignment, lift-off did not occur even if the LCL was elongated by up to 5 mm. However, lift-off occurred easily in the stance phase in femoral varus alignments of > 3A degrees with slight LCL slack. The contact forces of the tibiofemoral joint were influenced more by femoral varus alignment than by LCL laxity.
Aiming for neutral alignment in severely varus knees makes it difficult to achieve appropriate ligament balance. Our study suggests that no lift-off occurs with excessive LCL laxity alone in a neutrally aligned TKA and therefore that varus alignment should be avoided to decrease lift-off after TKA.
Case series, Level IV.
- リンク情報
- ID情報
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- DOI : 10.1007/s00167-015-3687-4
- ISSN : 0942-2056
- eISSN : 1433-7347
- PubMed ID : 26142165
- Web of Science ID : WOS:000380713600021