An apparatus to promote bone fusion between portions of bone tissue comprises a bone engagement member and a flexible retention member. The bone engagement member comprises (a) an extramedullary bone contacting main body with a first surface defining a hole in the main body and (b) an intramedullary bone engaging projection extending from the main body. The projection engages the intramedullary portions of at least one the portions of bone tissue. The projection includes a second surface that defines a retention passage in the projection. The retention passage is spaced away from the hole and oriented transversely relative to the hole. The flexible retention member is configured and dimensioned to extend through the retention passage and into the hole to help retain the projection in intramedullary engagement with the at least one of the portions of bone tissue.
