This 2008 AAOS Instructional Course Lecture by Parratte and Pagnano categorizes post-TKA instability into three types — extension instability, flexion instability, and genu recurvatum — and walks through the diagnosis, causes, and operative management of each. The central question: when a TKA fails due to instability, how do you identify which pattern is present and how do you fix it?
When a TKA patient reports vague instability, recurrent effusions, or stair difficulty with a well-fixed implant, examine the knee at 90° of flexion — you may be looking at flexion instability, the most commonly missed pattern.
Treatment requires formal gap rebalancing at revision, not just a poly exchange.
This 2008 AAOS Instructional Course Lecture by Parratte and Pagnano categorizes post-TKA instability into three types — extension instability, flexion instability, and genu recurvatum — and walks through the diagnosis, causes, and operative management of each. The central question: when a TKA fails due to instability, how do you identify which pattern is present and how do you fix it?
When a TKA patient reports vague instability, recurrent effusions, or stair difficulty with a well-fixed implant, examine the knee at 90° of flexion — you may be looking at flexion instability, the most commonly missed pattern.
Treatment requires formal gap rebalancing at revision, not just a poly exchange.