A device for positioning between two bone regions, the device comprising: a body extending along a longitudinal axis between two opposing ends, a first end configured to be positioned in use at or adjacent a first bone region and a second end configured to be positioned in use at or adjacent a second bone region; a wall defining an internal cavity extending between the first end and the second end, the internal cavity defined by an internal surface of the wall; at least a first stabilising arrangement extending into the internal cavity from the internal surface and located proximal the first end, the first stabilising arrangement comprising a first plurality of protrusions; at least a second stabilising arrangement extending into the internal cavity from the internal surface and located proximal the second end, the second stabilising arrangement comprising a second plurality of protrusions, wherein each of the first and second plurality of protrusions have opposing planar surfaces, an upper planar surface and a lower planar surface, and are spaced apart around the diameter of the internal surface of the internal cavity; wherein the upper planar surfaces face the first end of the device and the lower planar surfaces face the second end of the device, at least a portion of each of the upper and lower planar surfaces (77, 78) extending laterally with respect to the internal surface of the body part or full way across the internal cavity, such that bone growing into the internal cavity grows around the first or second stabilising arrangements creating areas of ingrowth and stabilisation around which the bone can grow, causing mechanical engagement and hooking around the first and second stabilising arrangements to secure the bone with respect to the device and provide stability to the bone region with respect to the device in more than one vector. a body extending along a longitudinal axis between two opposing ends, a first end configured to be positioned in use at or adjacent a first bone region and a second end configured to be positioned in use at or adjacent a second bone region; a wall defining an internal cavity extending between the first end and the second end, the internal cavity defined by an internal surface of the wall; at least a first stabilising arrangement extending into the internal cavity from the internal surface and located proximal the first end, the first stabilising arrangement comprising a first plurality of protrusions; at least a second stabilising arrangement extending into the internal cavity from the internal surface and located proximal the second end, the second stabilising arrangement comprising a second plurality of protrusions, wherein each of the first and second plurality of protrusions have opposing planar surfaces, an upper planar surface and a lower planar surface, and are spaced apart around the diameter of the internal surface of the internal cavity; wherein the upper planar surfaces face the first end of the device and the lower planar surfaces face the second end of the device, at least a portion of each of the upper and lower planar surfaces (77, 78) extending laterally with respect to the internal surface of the body part or full way across the internal cavity, such that bone growing into the internal cavity grows around the first or second stabilising arrangements creating areas of ingrowth and stabilisation around which the bone can grow, causing mechanical engagement and hooking around the first and second stabilising arrangements to secure the bone with respect to the device and provide stability to the bone region with respect to the device in more than one vector.