Methods and apparatus for affixing a retaining washer proximate an interbody region following a direct lateral interbody fusion (DLIF) procedure. The system includes an installation device characterized by a width dimension W and a length dimension L； a retaining washer having a substantially planar surface region, the retaining washer configured to retain an interbody graft within an interbody region； and a screw having a shaft configured to secure the retaining washer to a vertebral body. The screw and the washer are configured to orient the screw shaft along an angle θ, where θ is a function of W and L.
