Modular plate and cage elements and related methods

An interbody system for implanting between vertebrae, comprising:

• a cage having a cage body that includes
• a graft chamber having a volume that receives graft material,
• a sagittal wall that forms a portion of the graft chamber, and
• a wall membrane that forms another portion of the graft chamber, wherein the wall membrane interacts with a bone fastener.

An interbody system for implanting between vertebrae, comprising:

• a cage having a cage body that includes
• a graft chamber having a volume that receives graft material,
• a first sagittal wall having an inner wall surface that forms a first sagittal portion of the graft chamber,
• a second sagittal wall having an inner wall surface that forms a second sagittal portion of the graft chamber,
• an aft-wall having an inner wall surface that forms a posterior coronal portion of the graft chamber, and
• a wall membrane that forms an anterior coronal portion of the graft chamber;
• and
• an interbody device that includes an aperture that receives a bone fastener,
• wherein the wall membrane is directly adjacent to the bone fastener.