Ps型tka術後過伸展に対して再置換術を要した1例

Q: What is the clinical evidence from this study?

Study design: Case Report. Population: Genu recurvatum after PS-type total knee arthroplasty (n=1). Intervention: Revision surgery (insert exchange). Primary outcome: Resolution of hyperextension and instability.

Q: What does this research mean for the field?

Exchanging to a thicker polyethylene insert during revision surgery can successfully treat progressive genu recurvatum and hyperextension after posterior-stabilized total knee arthroplasty. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

禎大 古山; 尚明 加原; 児玉 有弥; 寛樹 神; Shogo Takaya; Shinya Yamada; 昌之 兒玉; 小瀬 靖郎; 井上 周

doi:10.5035/nishiseisai.75.492

September 24, 2026Orthopedics & TraumatologyOpen Access

Ps型tka術後過伸展に対して再置換術を要した1例

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Key result

Exchanging a 10mm for an 18mm insert resolves progressive genu recurvatum and instability after TKA.

n=1

Key Points

To describe the surgical management of progressive severe knee hyperextension occurring years after primary posterior-stabilized total knee arthroplasty.
Clinical and surgical evaluation of a 77-year-old female presenting with left knee weakness and 30° hyperextension 2 years and 4 months after primary PS-TKA.
Surgical revision involving mediolateral ligament balancing and exchange of the polyethylene tibial insert from 10 mm to 18 mm.
Intraoperative findings showed a transverse rupture of the posterior capsule and disappearance of the popliteus tendon, while the tibial insert post remained intact.
Increasing insert thickness from 10 mm to 18 mm effectively resolved the 30° hyperextension and restored joint stability.

Study Design

Type

Case Report (n=1)

Multicenter

No

Structured PICO

P

Population

A 77-year-old female who developed progressive genu recurvatum 2 years and 4 months after PS-type total knee arthroplasty, successfully treated with revision surgery.

I

Intervention

Revision surgery involving adjustment of varus/valgus balance and changing the insert from 10mm to 18mm.

O

Outcome

Improvement of hyperextension

Revision surgery with a thicker insert and balance adjustment can effectively treat progressive genu recurvatum following PS-TKA.

Limitations

Possibility of recurrence cannot be denied, requiring careful follow-up.
Findings are based on a single case report.
Possibility of future recurrence cannot be ruled out

Implication

Thicker insert exchange may treat late post-PS-TKA recurvatum; leaves open generalizability from this single case.

Abstract

【はじめに】今回我々はPS型TKA術後に経時的に反張膝が進行し，再置換にいたった稀な症例を経験した．【症例】77歳女性．KL分類Ⅳの左変形性膝関節症に対してPS型TKAを施行した．術前の左膝の可動域は伸展－20度と屈曲拘縮を，また左足関節可動域は背屈0度と背屈制限を認めた．術後2年4か月で，徐々に左膝の脱力感が出現し再診となった．その際，左膝は伸展30度で，荷重時に著明な反張膝を認めた．術中，後方関節包の横断裂および膝窩筋腱の消失を認めたが，インサートのポストの破損はなかった．内外反バランスを調整しインサートを10mmから18mmへ変更することで過伸展の改善を認めた．【考察】反張膝の再置換の術式については，程度に応じて厚いインサートへ変更や半拘束型もしくは拘束型への再置換が必要である．今回の症例は現時点での成績は良好であるが，今後再発の可能性は否定できないため慎重に経過観察をしていく予定である．

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Cite This Study

古山 et al. (2026) conducted a case report in Genu recurvatum after PS-type total knee arthroplasty (n=1). Revision surgery (insert exchange) was evaluated on Resolution of hyperextension and instability.

synapsesocial.com/papers/6ab9b4737822ec8fc3d8e132 https://doi.org/10.5035/nishiseisai.75.492

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Ps型tka術後過伸展に対して再置換術を要した1例

Key Points

Study Design

Structured PICO

Limitations

Implication

Abstract

Discussion

Cite This Study

Ps型tka術後過伸展に対して再置換術を要した1例

Key Points

Study Design

Structured PICO

Limitations

Implication

Abstract

Discussion

Cite This Study

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