A housing for an implantable device for mounting to a patient's bone is disclosed. The housing comprises one or more surfaces, wherein at least one of the surfaces is substantially orthogonal to an implant axis and is configured to abut the patient's bone, and a first osseointegrating protuberance extending from one of the surfaces, wherein a longitudinal axis of the first protuberance is disposed at an acute first angle relative to the implant axis.
