This disclosure describes a membrane configured to guide bone and tissue regeneration for a bone defect. The membrane may comprise a first layer, a second layer, one or more perforations, a binder, and/or other components. The first layer of the membrane may be configured to contact bone. The first layer may include pores configured to promote ingrowth of bone regenerating cells into the first layer. In some implementations, the first layer may be a continuous sheet of microporous material without large perforations. The second layer may be configured to substantially prevent fibrous connective tissue from growing into the bone defect. The second layer may comprise a relatively dense structure. The second layer may be fixedly coupled to the first layer. In some implementations, the perforations may comprise co-axial through-holes having common dimensions through the first layer and the second layer. The perforations may be configured to enhance ossification.

An expandable spinal implant includes a flexible body, an expander component, a fastener and an anti-reverse mechanism. The flexible body includes a base portion and flexible arms each having a free end and a fixed end connecting the base portion. The flexible arms surround an installation space. The expander component is partially in the installation space and exerts pressure on the free ends to move the free ends away from one another. The fastener includes a head portion and a screw portion. The head portion and the expander component are at opposite sides of the base portion. The screw portion passes through the base portion and screwed into the expander component. The anti-reverse mechanism is fixed to the base portion and blocks one side of the head portion located away from the expander component. The anti-reverse mechanism and the expander component are at opposite sides of the base portion.

An expandable spinal implant includes a flexible body, an expander component, a fastener and an anti-reverse mechanism. The flexible body includes a base portion and flexible arms each having a free end and a fixed end connecting the base portion. The flexible arms surround an installation space. The expander component is partially in the installation space and exerts pressure on the free ends to move the free ends away from one another. The fastener includes a head portion and a screw portion. The head portion and the expander component are at opposite sides of the base portion. The screw portion passes through the base portion and screwed into the expander component. The anti-reverse mechanism is fixed to the base portion and blocks one side of the head portion located away from the expander component. The anti-reverse mechanism and the expander component are at opposite sides of the base portion.