Which design concept is sometimes used to improve stability in hip and knee implants?

Which design concept is sometimes used to improve stability in hip and knee implants?

• A. Increased metal alloy density to improve strength.
• B. Dual mobility designs are a design option used to enhance stability in some implants.
• C. These designs require cemented fixation in all cases.
• D. They eliminate the need for modular components.

Answer: (B)

Stability in joint implants comes from reducing the risk of dislocation while preserving a useful range of motion. Dual mobility designs achieve this by adding a second articulation, which effectively increases the head size and jump distance—the amount of movement the joint can undergo before it can dislocate. In practice, a smaller head moves inside a mobile polyethylene liner, which itself articulates against the outer shell. This creates two contact interfaces and a larger overall articular radius, letting the joint accommodate more movement before impingement or dislocation occurs. This approach is especially helpful in situations with higher dislocation risk, such as revisions or certain patient anatomies. Other statements describe material density, universal cemented fixation, or removing modular components, which aren’t the mechanism by which stability is enhanced in this design.

Stability in joint implants comes from reducing the risk of dislocation while preserving a useful range of motion. Dual mobility designs achieve this by adding a second articulation, which effectively increases the head size and jump distance—the amount of movement the joint can undergo before it can dislocate. In practice, a smaller head moves inside a mobile polyethylene liner, which itself articulates against the outer shell. This creates two contact interfaces and a larger overall articular radius, letting the joint accommodate more movement before impingement or dislocation occurs. This approach is especially helpful in situations with higher dislocation risk, such as revisions or certain patient anatomies. Other statements describe material density, universal cemented fixation, or removing modular components, which aren’t the mechanism by which stability is enhanced in this design.