Constraint in total knee arthroplasty: when and what?

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Knee Arthroplasty

Background:

• Tibiofemoral instability is a recognized complication in total knee arthroplasty.
• Limited guidelines exist for managing unstable total knee arthroplasty.

Purpose of the Study:

• To review treatment options for tibiofemoral instability after total knee arthroplasty.
• To discuss component selection and expected outcomes for unstable total knee arthroplasty.

Main Methods:

• Literature review of treatment strategies for unstable total knee arthroplasty.
• Analysis of implant designs (cruciate-retaining, cruciate-substituting, constrained, linked) for managing instability.

Main Results:

• Cruciate-retaining designs require balanced ligaments.
• Cruciate-substituting components lack varus-valgus stability and do not address flexion laxity.
• Constrained designs may not offer long-term stability for severe instability.
• Linked implants provide reliable treatment for severe tibiofemoral instability and flexion laxity.

Conclusions:

• Management of tibiofemoral instability in total knee arthroplasty depends on the degree of ligamentous balance and laxity.
• Linked implants are the most reliable option for severe cases of instability and flexion laxity.