Metaphyseal compartment
Using a hollow chisel, the remnants of the superior and anterior part of the femoral neck are removed and the femur prepared to receive the femoral component.

Fig. 17 Opening of the canal with a box chisel.
Fig. 18 A broach (size 1 or 2) is inserted to locate the medullary canal.

Using the box chisel corresponding to the size of the implant, mounted on the broach handle, a core of cancellous bone is removed from the metaphysis taking care to preserve as much of the calcar as possible (Fig. 17). The smallest right or left broach (depending on the side involved) is then inserted to locate the medullary canal (Fig. 18).

Calibration reaming
In order to ensure that there will be no contact between the implant and the cortical diaphysis, reaming may be performed to the diameter of the selected implant as shown on the template. If there is a possible mismatch between the femoral component and the cortical bone of the diaphysis, reaming will be necessary, using a reamer diameter corresponding to the selected implant and as indicated on the template.

• the reaming guide is introduced, followed by the flexible reamers, beginning with the size corresponding to the diameter of the femoral medullary canal measured during pre-operative planning.
• reaming continues until the diameter matches the templated size of the implant.

Insertion of Broaches
Ensuring that they correspond to the operated side and beginning with the smallest size, the broaches are inserted up to the templated size.

The trial broach will indicate the size of the definitive implant if two conditions are met:

• The broach must be driven down to the correct level: the shoulder of the broach must be level with the digital fossa.
• The broach must be absolutely stable in the transverse (varus-valgus) direction and also in rotation.

It may be useful to check the correct position of the broach by measuring the distance between the medial edge of the broach and the inner cortex of the calcar.

If a trial broach smaller than the templated size shows absolute rotational stability, even though the reaming has been done correctly (this is particularly possible when the antero-posterior neck is narrow), do not attempt to use a larger size because of the risk of metaphyseal fissure or fracture.

Conversely, if the trial broach is unstable, there are three possible solutions:

• Try the next broach size, but use the reamer first and follow the information given by the template.
• Stabilise the templated implant by means of a corticocancellous bone graft taken from the resected part (but a graft should rarely be relied on to provide implant stability).
• Use an ABG II cemented Vitallium® stem.