Surgical instrument

1. A spiked head assembly for attachment to a tibial jig for use during an orthopaedic surgical procedure, the spiked head assembly comprising:

(a) a body which comprises an elongate member having a central longitudinal axis, a first end and a second end, superior and inferior surfaces, and at least one securing spike provided on the inferior surface towards the second end of the elongate member and configured to engage with a bone mass; and at least one arm extending from the elongate member in a direction perpendicular to the inferior surface; and

(b) a mount on the at least one arm which is configured to attach the assembly to the tibial jig,

in which:

the arm has an end and an inner surface;

the mount is secured to the end of the arm at a position spaced from the inferior surface of the elongate member;

the at least one arm is spaced apart from a plane that includes the central longitudinal axis and extends substantially perpendicularly to the inferior surface, such that the at least one arm, the mount and the inferior surface define an access space for the surgical procedure; and

the access space extends across the plane from the inferior surface to the mount and from the inner surface of the arm and continues across the plane.

2. The spiked head assembly according to claim 1 , wherein the at least one arm and a side edge of the elongate member are configured to subtend an acute angle.

3. The spiked head assembly according to claim 1 , wherein the body comprises a first arm and a second arm, the first arm and the second arm both extending from the elongate member in the same direction substantially perpendicularly to the inferior surface, the first and second arms being spaced apart laterally from each other, and from the plane including the central longitudinal axis and which extends substantially perpendicularly to the inferior surface, such that the access space is defined by the first arm, the second arm, the mount and the inferior surface.

4. The spiked head assembly according to claim 3 , wherein the body includes a crosspiece connected between the first and second arms.

5. The spiked head assembly according to claim 3 , wherein the mount comprises a body having a pair of grooves provided on opposite sides of the body and arranged to receive respective terminating ends of the first and second arms.

6. The spiked head assembly according to claim 5 , wherein the mount body comprises a pair of body portions which, when in a closed position are configured to clamp the mount to the tibial jig.

7. The spiked head assembly according to claim 1 , wherein the elongate member comprises a first part and a second part, the first part being attached to the at least one arm and the second part including the at least one securing spike and being detachably connected to the first part for slidable movement relative to the first part along the central longitudinal axis.

8. The spiked head assembly according to claim 7 , wherein the first part includes a grooved recess and the second part includes a lipped portion, the lipped portion being arranged to be receivable into the grooved recess for cooperation therewith, the second part including a securing means for securing the first part to the second part when the lipped portion is received into the grooved recess.

9. The spiked head assembly according to 1 , wherein the elongate member has a reduced profile at the second end.