Round and ergonomic implants are both typically round in outline, so rotation is not the deciding factor. The difference lies in how they behave with body position.
Round
Consistent shape regardless of position; upper-pole fullness set by the profile you choose. Predictable, widely available and well studied.
Ergonomic
Designed to shift between a rounder shape lying down and a teardrop slope standing, aiming for natural movement and a sloped upper pole when upright.
Bottom line
Ergonomic implants target patients who want natural dynamic behaviour without fixed anatomical shaping. Round implants remain the benchmark for predictability and choice. Discuss availability, cost and your surgeon's experience before deciding.