One fastener has a shaft with proximal and distal ends. Threading extends along the shaft from the distal end, and a head is at the proximal end. A channel passes entirely through the shaft such that a first lateral portion of the shaft is on one side of the channel and a second lateral portion of the shaft is on an opposite side of the channel. The channel is inset from the distal end. A hollow area in the shaft extends from the distal end toward the proximal end. The hollow area has a width that is greater than a width of the channel, and a biasing member is positioned inside the hollow area. An insert has an interior portion and an exterior portion. The interior portion is configured for positioning in the channel and the hollow area, and the exterior portion is configured to be located outside the shaft.