Apparatus for the perforation of the femur and the tibia in surgical operations

The apparatus is designed for the installation of front and rear crossed prosthetic ligaments in the articulation of the knee, and includes a stem which extends, at one end, with an arc-like tapered portion the end whereof is adapted to be inserted through the surgical opening at the knee, to pass between the tibial plate and the condyloid cavity and to be positioned in the exact outlet position of the bore to be provided, a small block having at least one hole for a screw for fastening to the bone and a seat for coupling to a spherical joint, an arm which ends at one end with the spherical joint coupled to the seat, bears at the other end a clamp with a groove and countergroove for its longitudinal sliding and locking along the stem and has coupling elements for interchangeable bushes for guiding the drilling tool.

BACKGROUND OF THE INVENTION 
The present invention relates to an apparatus for the perforation of the 
femur and the tibia in surgical operations, particularly for installing 
front and rear crossed prosthetic ligaments in the articulation of the 
knee. 
In a recent implantological method the ligaments of the knee can be 
replaced with bands or strands of particular biocompatible materials: such 
bands are inserted in two corresponding bores which must have their inlets 
substantially on the front faces of the tibia and of the femur and their 
outlets in the rear regions respectively of the tibial plate and of the 
condyloid cavity of the femur. The ends of the bands, conveniently 
provided with slots or the like, are connected at the bores inlets by 
screws which are intended to be definitely removed, after the fibers have 
biologically associated with the bone. 
It has been observed that a long time is required by this surgery for the 
installation of the prosthetic ligaments because of the difficulties 
encountered in providing the bores in the bones. For a good operation of 
the knee joint, in fact, bore outlets must be located in extremely precise 
positions (surgical points), defined by the surgeon, which, however, are 
located behind the knee on the opposite side with respect to that on which 
the patient is operated. 
Currently, a first small test bore is drilled using a small bit with great 
care and caution, checking the alignment as the bit drills through the 
bone; the surgeon then manually checks the location of the bore outlet by 
passing a finger behind the articulation; if the bore outlet is considered 
to be acceptably located, the bore is progressively widened with 
increasingly larger-diameter bits with the aid of steel guide wires 
inserted in the bore; if instead the bore outlet is in a position which is 
considered unacceptable, another bore is drilled. 
It is obvious that, also in view of the fact that the bore is inclined with 
respect to the surface of the bone, there are great difficulties in 
drilling the bores correctly. 
Another great difficulty is due to the fact that in the bore outlet regions 
there are vessels and tissues which must absolutely not be damaged by the 
drill bit: finally the bore outlets must be bevelled to avoid stresses 
which may damage the fibers of the band. 
SUMMARY OF THE INVENTION 
The aim of the present invention is to eliminate the abovementioned 
disadvantages and to provide an apparatus which allows to perform the 
perforation of the femur and the tibia in an extremely fast and precise 
manner with the assurance of not damaging the underlying tissues so as to 
make the surgical operation much more rapid and less traumatic. 
Within this aim, an object of the present invention is to achieve the above 
described aim with a simple structure which is relatively easy to 
manufacture, is safe and effective in use and has a relatively modest 
cost. 
This aim and these objects are achieved by an apparatus for the perforation 
of the femur and the tibia in surgical operations, particularly for 
installing the front and rear crossed prosthetic ligaments in the 
articulation of the knee, characterized in that it comprises: a stem 
having an arc-like tapered portion, one end of said arc-like portion being 
adapted to be inserted in the surgical opening at the knee and pass 
between the tibial plate and the condyloid cavity and to be positioned in 
the exact outlet position of a bore to be drilled, a small block having at 
least one hole for a screw for fastening it to the bone, said block having 
a seat for engaging a spherical joint, an arm having said spherical joint 
at one end, said arm bearing a clamp at its end opposite said spherical 
joint, said clamp having a guide means, said clamp being slideable and 
lockable along said stem and having coupling means for interchangeable 
bushes for guiding a drilling tool.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With reference to the figures, reference numeral 1 generally indicates the 
apparatus according to the invention for the perforation of femur 2 and of 
tibia 3 for installing the front and rear crossed prosthetic ligaments in 
the articulation of the knee 4. 
The apparatus 1 comprises a preferably rectilinear prismatic stem 5 having 
a hexagonal cross section and a handgrip 6 at one end. At the opposite 
side of the handgrip, the stem 5 extends in an arc-like tapered portion 7 
which has a mixed-line configuration and ends with a rounded tip 8. 
According to a different aspect of the invention the stem 5 has a cross 
section half circular and half square-cornered, as illustrated in the 
figures. 
Reference numeral 9 indicates a small block which has at least one hole 10 
(in the illustrated embodiment there are two holes 10a and 10b), for 
fastening the block to the bone with a screw 11, and has a seat 12 for its 
connection to a spherical joint 13. 
An arm 14 has a joint 13 at one end and a clamp 15 at the other end. The 
clamp 15 has a jaw 16 rigidly associated with the arm 14. A jaw 19 is 
articulated to said jaw 16 by means of a dowel 17. The jaws 16 and 19 
respectively have a groove 20 and a countergroove 21, which match the 
outer cross section of the prismatic stem 5. 
On the opposite side with respect to the dowel 17, the jaw 16 defines a 
fork at which the terminal eyelet of a threaded stem 23 is articulated by 
means of a pivot 22; the jaw 19 has, in turn, its end in the shape of a 
fork in which the threaded stem 23 is insertable and is engaged by a wing 
nut 24: by tightening the wing nut 24 it is possible to rigidly couple the 
arm 14 in any position along the stem 5 and prevent its relative rotation. 
The arm 14 can thus be locked in any position substantially on the plane 
defined by the stem 5 and by the mixed-line portion 7. In the arm 14, at a 
distance from the stem 5 which is equal to the distance of the stem from 
the tip 8, a counterbush 25 is provided which has an axis parallel to the 
stem 5 and is directed towards the tip 8. A screw 26, having an actuation 
knob 26a, is screwable to an inclined threaded hole provided in the 
counterbush 25 and constitute a coupling means for an interchangeable bush 
27 which is internally traversed by a guide hole 28 for the bit 29 which 
is adapted to drill the bore in the bone: the bushes are progressively 
replaced with others having a larger-diameter hole for progressively 
larger bits. 
The operation of the apparatus according to the invention is as follows: 
through a surgical entry point executed in front of the tibia or of the 
femur, the tip 8 is introduced between the tibial plate and the condyloid 
cavity until said tip is in the exact surgical point in which the bore to 
be drilled must have its outlet; the small block 9 is fixed to the femur 
or to the tibia by means of at least one screw 11. The arm 14 is rotated 
about the small block 9 and the clamp 15 is slipped along the stem 5 and 
subsequently locked by means of nut 24 so as to move the tip 8 into the 
exact outlet position U of the bore F which is to be drilled and the 
counterbush 25 into alignment with the bore inlet I. Once the 
smallest-diameter bush 27 is mounted, a first small bore with a reduced 
diameter is drilled with the bit 29 and subsequently, by changing the bush 
and the bit, the bore is widened until it reaches the required diameter. 
The block 9 and thus the entire apparatus are now removed, and the outlet U 
is bevelled by means of a mushroom-shaped bit constituted by a tool stem 
30 which is coupled to a drill and ends with a mushroom-shaped head 31 
having its abrasive part 32 directed towards the stem. The head 31, which 
is slightly smaller in diameter than the bore F, is caused to pass in the 
hole and to protrude from the outlet U; by slightly pulling the bit 
backwards, moving it peripherally all around, it is possible to bevel the 
edge of outlet U. 
To avoid damaging the underlying tissues, before inserting the tool stem 
30, a flat strip 33 is inserted in the hole F. The strip 33 is folded 
along its entire length in a half-circle and ends with a semicircular 
bottom 34 adapted to keep away the tissues which must not be affected 
while operating with the head 31 on the other side of the edge. 
The screws and holes previously used to lock the small block 9 are used for 
fastening the ends of the prosthetic band, which are conveniently provided 
with eyelets. 
It has thus been observed that the invention achieves the intended aims. 
The invention thus conceived is susceptible to numerous modifications and 
variations, all of which are within the scope of the inventive concept. 
Furthermore all the details may be replaced with other technically 
equivalent elements. 
In practice, the materials employed, as well as the shapes and dimensions, 
may be any according to the requirements without thereby abandoning the 
scope of the protection of the following claims.