The femoral neck attaches to the body of the stem through a unique Dual Press™ connection* that is simple, robust, and very stable. This modular design allows a large selection of necks, enabling the proper combination of anteversion angle, lateral offset, and neck length/leg length, to restore proper soft tissue tension and joint biomechanics.
The modular attachment mechanism is new to orthopaedic implants, but the concept was derived from conventional mechanical tool design. The distinguishing feature is that the hole in the stem and the mating peg on the neck are cylindrical rather than tapered. To create a mechanical lock an interference fit is created at the proximal and distal ends of the mating peg. The forces required to seat the neck are relatively small, and easily generated with the stem in situ. This design eliminates the need for tapers, which can be difficult to manufacture and prone to dissociation. For all practical purposes, the stem will perform as a one-piece stem (with a conventional modular head) after attachment of the neck.