Purpose

The aim of this systematic review was to evaluate the evidence on the existence of midflexion instability in primary total knee arthroplasty and which factors might contribute to this condition.

Methods

A comprehensive search of PubMed, Medline, Cochrane, CINAHL, and Embase databases was conducted since the inception of the database to July 2019. All relevant articles were retrieved, and their bibliographies were hand searched for further references on midflexion instability in primary total knee arthroplasty. The search strategy yielded 28 articles. After duplicate removal titles, abstracts and full text were reviewed. Fifteen studies were assessed for eligibility, 8 studies were excluded because they did not fully comply with the inclusion criteria. Seven articles were finally included in this systematic review.

Anteroposterior translation, total knee arthroplasty design such as posterior-stabilized or posterior-cruciate-retaining total knee arthroplasty, joint line position with posterior condylar offset and joint gaps were considered to significantly influence midflexion stability.

Results

Based on this systematic review anteroposterior translation of ≥ 7 mm was an independent risk factor for midflexion instability at 30° knee flexion. Joint line position can be altered by up to 5 mm without measurable changes in joint stability and both an increase and a decrease in posterior condylar offset led to 30° midflexion instability.

Conclusion

Midflexion instability in primary total knee arthroplasty remains to be not entirely understood. Due to the low quality of available evidence, it is difficult to make any definitive conclusions. The factors which can lead to this condition were analyzed in this review, furthermore, we did not find exhaustive evidence on midflexion instability existence as an isolated entity. Nonetheless, this review will form a baseline for future research and creates awareness for the routine assessment of midflexion instability in primary total knee arthroplasty.

Level of evidence

IV.

目的

这项系统评价的目的是评估在原发全膝关节置换术中存在屈曲中枢不稳定性的证据，以及哪些因素可能导致这种情况。

方法

自数据库建立到2019年7月，对PubMed，Medline，Cochrane，CINAHL和Embase数据库进行了全面搜索。检索了所有相关文章，并手工检索了他们的参考书目，以获取有关初次全膝关节置换术中屈不稳的进一步参考。 。搜索策略产生了28篇文章。重复删除标题后，将对摘要和全文进行审查。评估了15项研究的资格，排除了8项研究，因为它们不完全符合纳入标准。这篇系统评价最终包含了七篇文章。

前后路平移，全膝关节置换术设计（例如后路稳定或后交叉保留全膝关节置换术），具有后con突偏移的关节线位置和关节间隙会严重影响中屈稳定性。

结果

根据此系统评价，≥7 mm的前后移位是30°屈膝时中屈不稳的独立危险因素。关节线位置最多可改变5 mm，而关节稳定性没有可测量的变化，后con偏移的增加和减少都会导致30°中屈不稳。

结论

初次全膝关节置换术的中屈不稳定性仍有待完全了解。由于现有证据质量低下，很难做出任何明确的结论。在这篇综述中分析了可能导致这种情况的因素，此外，我们没有找到关于中屈不稳定性作为独立实体存在的详尽证据。尽管如此，本综述将为将来的研究奠定基础，并提高人们对常规全膝关节置换术中屈不稳定性常规评估的认识。

证据水平

IV。