An orthopaedic intramedullary fixation apparatus and system for use in hip and femur facture surgery comprises an intramedullary nail, a dynamic lag screw structure comprising a longitudinal sheath and a lag screw, and securing means to fix the intramedullary nail relative to a femur. A dynamic channel created by the lag screw structure allows the lag screw to adjust dynamically, and thereby may permit further compression of the fractured bone to an optimal level as a patient begins to bear weight on it following surgery. Surgical fixation may be expedited, as a favorable point of access for a lag screw may be determined readily, particularly with obese patients in whom access to the trochanter may be problematic. Complications during surgery, such as accidental fracturing of the femoral neck and head and over-penetration of the lag screw may be avoided.
