An improved fastener apparatus includes an outer sleeve which is moved into a patient's body tissue. A distal end portion of the outer sleeve is expanded in the patient's body tissue. An inner sleeve is moved axially through the outer sleeve and a distal end of the inner sleeve is expanded in the patient's body tissue. The fastener apparatus may be provided with an external thread convolution on either or both of the inner and outer sleeves. During expansion of the distal end portion of either the inner or outer sleeve, a proximal end portion of the outer sleeve may be gripped and pulled to offset forces applied to the distal end portion of one of the sleeves. Although inner and outer sleeves may advantageously be utilized, the fastener apparatus may be constructed with only a single sleeve if desired.