Which statement about the relationship between flap lesions and subchondral bone cysts in OCD is correct?

Which statement about the relationship between flap lesions and subchondral bone cysts in OCD is correct?

• A. Flaps occur in high shear regions.
• B. Cysts form in areas of maximal shear loads.
• C. Flaps occur in regions of high compressive loads.
• D. Flaps occur in regions of high shear forces, while subchondral bone cysts occur in areas subjected to maximal compressive loads.

Answer: (D)

In OCD, different parts of the joint are subjected to different kinds of mechanical stress, and this shapes how lesions develop. Flap lesions form where shear forces across the cartilage-subchondral interface are high, causing cartilage to fissure and eventually detach as a loose piece. Subchondral bone cysts arise under areas of maximal compressive loading, where repeated compression leads to microfractures in the subchondral bone and intrusion of fluid, forming a cyst beneath the cartilage. So the best statement reflects both patterns: flaps in high shear regions, and cysts in areas subjected to maximal compressive loads. The other ideas don’t fit because they tie flaps or cysts to the opposite loading conditions.

In OCD, different parts of the joint are subjected to different kinds of mechanical stress, and this shapes how lesions develop. Flap lesions form where shear forces across the cartilage-subchondral interface are high, causing cartilage to fissure and eventually detach as a loose piece. Subchondral bone cysts arise under areas of maximal compressive loading, where repeated compression leads to microfractures in the subchondral bone and intrusion of fluid, forming a cyst beneath the cartilage.

So the best statement reflects both patterns: flaps in high shear regions, and cysts in areas subjected to maximal compressive loads. The other ideas don’t fit because they tie flaps or cysts to the opposite loading conditions.