Securing a second object to a first object

A method of anchoring a connector in a first object, wherein the connector comprises thermoplastic material in a solid state, the method comprising the steps of:

• bringing the connector into physical contact with the first object,
• rotating the connector relative to the first object around a proximodistal rotation axis and exerting a relative force by the connector onto the first object, until a flow portion of the thermoplastic material of the connector becomes flowable and flows relative to the first object, and
• stopping rotation of the connector, whereby the flow portion anchors the connector relative to the first object,
• wherein at least one of the following conditions is fulfilled:
• A. the connector is shaped so that a distal-most end thereof is different from a contact point on the proximodistal rotation axis;
• B. a portion of the connector has a macroscopic surface roughness;
• C. the connector comprises a portion of a second material different from the thermoplastic material, wherein said second material is solid and does not become flowable, and wherein said portion either extends to the distal end or extends through a middle plane perpendicular to the axis, or both;
• D. during the step of rotating, the connector is subject to an orbital movement;
• E. the connector has an inner portion and a proximal connecting portion with a distally facing connecting protrusion, wherein during the step of rotating, the connecting protrusion is pressed against a proximally facing end face of the first object and a surface part of the inner portion is pressed against a first object structure distally of the proximally facing end face;
• F. the first object comprises a structure of fibers or a foam material, and the flow portion is caused to flow into the structure of fibers or into pores of the foam material, respectively.