Primary Total Knee Arthroplasty Revised for Instability: A Detailed Registry Analysis

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Arthroplasty Research

Background:

• Instability is a frequent yet poorly understood complication following total knee arthroplasty (TKA).
• Understanding factors influencing TKA instability is crucial for improving patient outcomes.

Purpose of the Study:

• To investigate patient and prosthesis characteristics associated with TKA revisions for instability.
• To analyze trends in TKA instability and identify predictors of further revision surgery.

Main Methods:

• Analysis of a large national registry dataset comprising 2605 TKA revisions for instability.
• Utilized Kaplan-Meier estimates for cumulative revision percentages and Cox proportional models for revision rate comparisons.
• Examined the impact of prostheses used in the first revision on the rate of subsequent revisions.

Main Results:

• TKA revisions for instability increased from 6% in 2003 to 13% in 2019.
• Minimally stabilized prostheses, male sex, and age ≥65 years were associated with lower revision risk.
• Revision involving both femoral and tibial components, or using constrained components, resulted in a lower second revision rate.

Conclusions:

• The incidence of TKA revision due to instability is increasing.
• Replacing both femoral and tibial components demonstrates a lower rate of subsequent revision compared to isolated insert exchange.
• Recurrent instability is a significant concern after TKA revision surgery.