Method and device for adjusting a long-bone conformation

An osteotomy procedure for adjusting the conformation of a long-bone is described. Illustratively, a proximal tibial osteotomy procedure produces two relatively rotatable long-bone segments. A jig including a body and having two pins extending therefrom in the same direction in a plane containing the long axis of the jig preferably is used to adjustably fix the two segments relative to one another with each pin securely fixed within a corresponding one of the segments. Importantly, at least the distal pin is bendable such that a desired rotation with two degrees of freedom is achievable between the two to-be-fixed segments. By bending the distal pin in a region thereof extending between the jig body and the distal segment, any desired relative rotation may be achieved between the segments. Correction of any and all conditions including varus, valgus, internal and external rotation may be accomplished in a single osteotomy procedure.

TECHNICAL FIELD 
The invention involves adjustment of an undesirable long-bone conformation, 
e.g. the conformation of a tibia, femur, radius/ulna or humerus, by 
relative rotation of two proximal osteotomy-produced long-bone segments. 
More specifically, it concerns adjustment using a jig having pins 
extending therethrough into such segments, whereby the distal pin is bent 
to produce a desired rotation of the distal segment that is pinned 
thereby. A preferred device and manner of practicing the invention is 
described in conjunction with veterinary surgery on the leg of a canine to 
correct an abnormal knee conformation. 
BACKGROUND 
A tibial plateau-leveling osteotomy procedure is known that permits 
adjustment of the axis of the tibia relative to that of the femur. Such a 
procedure is described in my U.S. Pat. No. 4,677,973 entitled PROXIMAL, 
TIBIAL OSTEOTOMY FOR LEVELING A TIBIAL PLATEAU, which issued Jul. 7, 1987. 
In accordance with that procedure, a through curvilinear cut is made in 
the proximal tibia to separate the metaphysis from a distal tibial 
segment. The axis of the curved cut is normal to the sagittal plane. The 
separated tibial segment is rotated a desired direction and angle about 
the knee joint. The relatively rotated metaphysis and distal tibial 
segment are then fixed relative to one another, as by pinning. The 
procedure may be used to solve such problems as cranial tibial thrust. The 
procedure described therein does not address varus, valgus, internal or 
external rotation of a long-bone segment. 
SUMMARY OF THE INVENTION 
Briefly, the invention involves a long-bone osteotomy procedure that 
produces two relatively rotatable bone segments separated by a transverse 
cut. A jig including a body and having two pins extending therefrom in the 
same direction in a plane containing the long axis of the jig preferably 
is used to adjustably fix the two segments relative to one another with 
each pin securely fixed within a corresponding one of the segments. 
Importantly, at least the distal pin is bendable such that a desired 
rotation with two degrees of freedom is achievable between the two 
to-be-fixed segments. By bending the distal pin in a region thereof 
extending between the jig body and the distal segment, any desired 
relative rotation may be achieved between the segments. Correction of any 
and all conditions including varus, valgus, internal and external rotation 
may be accomplished in a single osteotomy procedure. 
These and additional objects and advantages of the present invention will 
be more readily understood after a consideration of the drawings and the 
detailed description of the preferred method.

DETAILED DESCRIPTION OF THE DRAWINGS AND BEST MODE FOR CARRYING OUT THE 
INVENTION 
Referring first to FIG. 1, an invented jig for imparting rotation or 
torsion or both between two cut and separated bone segments is shown at 10 
in isometric view. Jig 10 may be seen in its preferred embodiment to 
include an elongate body 12 having a proximal articulable arm region 12a 
and a distal articulable arm region 12b; a first, elongate, substantially 
straight pin 14 extending substantially perpendicularly through proximal 
region 12a, with first pin 14 being configured for secure fixation within 
a proximal segment 16a of a bone such as a tibia 16; and a second, 
elongate, bent or angular pin 18 extending along a proximal extent thereof 
substantially perpendicularly through distal region 12b and substantially 
parallel with first pin 14, with second pin 18 extending along a distal 
extent 18b thereof at a predefined angle A relative to that of a proximal 
extent 18a and with second pin 18 being configured for secure fixation 
within distal segment 16b of the bone. Preferably, predefined angle A 
subtended between proximal extent 18a and distal extent 18b of second pin 
18 is between approximately 135-degrees and 165-degrees, as shown in FIG. 
1. (Those of skill in the art will appreciate that shown only 
fragmentarily in FIGS. 1 through 4 for the purpose of context are the 
humerus to which the tibia connects proximally and the ankle joint to 
which the tibia connects distally.) 
It may be seen from FIGS. 1 through 4 that, in accordance with a preferred 
embodiment of the invention, proximal and distal regions 12a, 12b securely 
capture pins 14, 18 within opposite articulating arms that are pivotable, 
but securably so, within open slotted opposite end regions of body 12. 
This structure permits the articulable arms with their affixed pins to be 
oriented relative to body 12 through a wide range of angles that render 
apparatus 10 more conveniently manipulated relative to the osteotomy 
patient's long-bone. It will be appreciated that the articulable arms may 
be secured in a desired pivotal position relative to elongate body 12, 
e.g. the substantially perpendicular orientation shown in FIGS. 1 through 
4, by the use for example of a set screw (illustrated in the drawings as 
being disk-shaped and Allen-wrench securable) in either end region. 
Those of skill in the art will appreciate that pins 14, 18 preferably are 
dimensioned to extend entirely through both cortices of the long-bone 
segments being adjusted, thereby to better secure the adjusted position of 
the bones, as illustrated best perhaps in FIGS. 5A through 5C. This is 
especially important when the long-bone being torsed or otherwise adjusted 
has a substantially hollow interior or void, as is typically the case with 
a proximal tibia. Those of skill also will appreciate that pins 14, 18 
preferably extend through and slightly beyond the holes formed in the 
distal and proximal end regions of elongate body 12, as this facilitates 
gripping of the pins and further rotational adjustment thereof after the 
pins are secured within the long-bone segments. 
Pins 14, 18 may be made of any suitable material and hardness. To some 
extent, pin size is patient limb size-dependent. Pin diameters range 
typically range from 1/8-inch to 3/32-inch, and pin lengths range 
typically from three to five inches. One suitable material, that has a 
desirable hardness and flexibility is 316L or 316LVM (low-carbon vacuum 
melt). The flexibility of the pins used in accordance with the invented 
jig is important in that it permits some flexing, to accommodate 
procedural tolerances, yet it has sufficient memory to maintain an 
imparted bend. Body 12 also may be made of any suitable material and may 
have two or more preferably parallel, and preferably perpendicular, holes 
formed in the arm regions 12a, 12b thereof through which pins 14, 18 may 
extend, and may be selectively slid axially or rotated around their axes, 
and yet may be captured, as by form-fitting them or by the use of a set 
screw (not shown). The slidable and rotatable but secure capture of pins 
14, 18 within body 12 of apparatus 10 permits the body to be closer or 
further from the patient and for an optional step of torsing jig 10, as 
will be described by reference to FIGS. 4 and 5C. 
The preferred method of the invention may be understood to achieve 
adjustment of the orientation of any distal bone relative to the proximal 
bone. For example, a distal tibia having an undesirable orientation or 
rotation may be adjusted by the invented method relative to the knee 
joint, or a distal femur having an undesirable orientation or rotation may 
be adjusted by the invented method relative to the hip joint. Those of 
skill in the art will appreciate that adjustment of any long-bone relative 
to a joint of which the long-bone is a part is within the spirit and scope 
of the invention, although the invented method is described and 
illustrated herein as involving a canine's proximal tibia and its 
associated knee joint. 
Turning now to FIG. 2, it may be seen that the first step of the preferred 
method of the invention involves producing a transverse through cut C in a 
proximal region of bone 16 to produce separated proximal and distal bone 
segments such as proximal tibial bone segment 16a and distal tibial bone 
segment 16b. Osteotomy cut C may be generally planar or generally 
cylindrical or otherwise curvilinear. If it is desired to achieve, 
intra-operatively, tibial plateau leveling, then it is preferred that the 
cut be cylindrical in accordance with the teachings of my above-referenced 
patent. It will be appreciated that, if no tibial plateau leveling is 
required, a simple planar cut will permit the needed tibial-knee joint 
adjustment. Any osteotomy cut that produces separated long-bone segments 
is contemplated, and is within the spirit and scope of the invention. 
Referring still to FIG. 2, it may be seen that an intermediate step of the 
preferred method involves the use of jig 10 described above by reference 
to FIG. 1. Preferably, jig 10 is affixed to bone 16, with elongate 
proximal pin 14 extending therefrom into secure and preferably through 
engagement with proximal bone segment 16a and with elongate distal pin 18 
extending therefrom into secure and preferably through engagement with 
distal bone segment 16b. It will be appreciated that by pin is meant any 
suitable temporary fixation device such as a pin or screw. Often, a distal 
region of such a pin is pointed and threaded for more secure engagement 
with the bone, although such is not required by the present invention. 
Turning now to FIG. 3, it may be seen that at least one of proximal pin 14 
and distal pin 18 is bent, in accordance with a later step of the 
preferred method of the invention, in a region between body 12 of jig 10 
and the engaged bone segment. Importantly, the bending step is performed 
after the affixing step in accordance with the preferred method of the 
invention, as it is the bending step that promotes rotation and/or torsion 
of the affected limb. Preferably, the bending is performed in a region of 
distal pin 18 that is approximately midway along the extent thereof 
between body 12 and bone 16. Nevertheless, those of skill in the art will 
appreciate that, alternatively yet within the spirit and scope of the 
invention, the pin may be bent closer to the body or closer to the bone, 
as access and pin length permit, and that proximal pin 14 may be bent 
instead or in addition to the bending of distal pin 18, thereby to promote 
desired rotation of distal bone segment 16b relative to proximal bone 
segment 16a. 
It may be seen from FIG. 3 that the bending step produces an obtuse angular 
orientation between first, proximal extent 18a of distal pin 18 that is 
proximate jig 10 and a second, distal extent 18b of distal pin 18 that is 
in engagement with distal bone segment 16b. Preferably, the bending step 
produces an angular orientation of between approximately 145-degrees and 
175-degrees, depending upon the desired degree of imparted rotation and 
torque, which range of angles has been found to be useful in correcting 
tibial and femoral conformations. More preferably, the bending step 
produces an angular orientation of approximately 165-degrees, as 
15-degrees (180-degrees minus 165-degrees) is a more typical extent of 
correction required and as 15-degrees is the amount of correction that is 
imparted by forming an angle subtended between the first and second 
extents of the pin at approximately 165-degrees. 
The most extreme undesirable conformations may require as much as 
approximately 35-degrees, or more, of correction, corresponding to a 
subtended angle of approximately 145-degrees. Slight undesirable 
conformations may require as little as approximately 5-degrees of 
correction, corresponding to a subtended angle of approximately 
175-degrees. Thus, those of skill will appreciate that the bending step 
may be performed in such manner that any desired angle is subtended by 
first and second distal pin extents 18a, 18b. This is one of the excellent 
advantages of the invention: any desired angle is easily achieved by the 
claimed bending of a pin into a desired angular configuration. 
It may be seen from FIG. 3 that the bending step preferably is performed in 
such manner that first and second extents 18a, 18b of distal pin 18 define 
a plane P.sub.p (refer briefly to FIG. 5B, the plane of which corresponds 
with this plane P.sub.p), which intersects the patient's sagittal plane 
P.sub.s (a vertical plane normal to that of FIG. 5B, and one shown in FIG. 
6). It also may be seen from FIG. 3 that the bending step preferably is 
performed in such manner that first and second extents 18a, 18b of distal 
pin 18 define a plane that also intersects the patient's frontal plane 
P.sub.F (a plane normal to sagittal plane P.sub.S, i.e. a plane that it is 
parallel with the plane of FIG. 5B, and one shown in FIG. 6, described 
below). Those of skill in the art will appreciate that one or both 
intersections may be effected simultaneously by the manner in which the 
bending step of the invented method is performed. This is another 
excellent advantage of the invention over prior art jigs that permit 
rotation of a pin only about the jig's long axis or in a plane parallel to 
a plane containing the jig's long axis. 
Those of skill will appreciate that, because the pins of jig 10 are 
securely attached to the distal and proximal long-bone segments and are 
securely fixed within jig 10, the bending of distal pin 18 results in the 
commensurate torsing of distal segment 16b relative proximal segment 16a 
(refer to FIG. 3 in which such torsing, or relative rotation, is 
illustrated schematically by a curved arrow). It may also be seen from 
FIG. 3 that such bending step produces an incidental angular adjustment of 
the distal end of long-bone 16 (refer again to FIG. 3 in which such 
incidental angular adjustment is illustrated schematically by non-coaxial, 
or intersecting, dash-dot and dash-dot-dot lines corresponding, 
respectively, with the central axis of segment 16a and segment 16b) 
FIG. 4 may be seen to be similar to FIG. 3, but shows a further, optional, 
step in the preferred method of adjusting a long-bone conformation. In 
FIG. 4, jig 10 has been rotated generally clockwise (relative 
approximately to the plane of the drawings) through a defined angle with 
the pins securely fixed within the long-bone segments. The result of such 
jig rotation is the restoration of the coaxial orientation of segments 
16a, 16b to compensate for the slight downward shift that resulted, as 
illustrated in FIG. 3, from the bending of pin 18 to cause rotational 
adjustment between the long-bone segments. This rotation of jig 12 is 
illustrated schematically in FIG. 5C to be described below. 
Not shown in FIG. 4 is a step that forms no part of the present invention 
by which fixation of the adjusted long-bone segments is accomplished, as 
by any suitable method including internal or external fixation devices 
such as pins, brackets, etc. Also not shown in FIG. 4 is a final step in 
the preferred osteotomy whereby any needed bone grafting is performed in 
and around the interface between the adjusted long-bone segments. Such 
will be understood by those skilled in the art to promote better fixation 
and faster osteosynthesis, especially in a case where--by the nature of 
the transverse cut or the resulting configuration between the cut, 
separated, adjusted and fixated segments--there is a bone material 
deficit. 
FIGS. 5A through 5C schematically illustrate in an axial view along the 
tibia the tibial configuration before and after the pin-bending step and 
after the jig-torsing step. Briefly, FIG. 5A represents tibia 16 by its 
two cut and separated segments 16a and 16b shown as concentric circles, 
with an intermediate portion thereof shown in dash-dot outline as a 
smaller circle that is not concentric with the others. FIG. 5B shows that, 
with the bending of pin 18 of jig 12 as described and illustrated herein, 
distal tibial segment 16b may be shifted and rotated (as indicated by two 
curved arrows) relative to proximal tibial segment 16a, whereby a canine's 
hock joint is rotated internally or externally to correct a torsed 
condition of the tibia and whereby simultaneously the distal tibial 
segment is reoriented relative to the proximal tibial segment and the knee 
joint to correct a varus (knock-kneed) or valgus (bowlegged) condition of 
the canine's rear leg. Finally, FIG. 5C shows a final configuration of 
proximal and distal tibial segments 16a, 16b corresponding with that of 
FIG. 4 in which, by torsing jig 10 while pins 14, 18 are securely fixed in 
their respective long-bone segments, the distal and tibial segments are 
restored to a condition of being substantially coaxial, but with the 
imparted torsional adjustment therebetween. 
If it is desired or needed to level the patient's tibial plateau, while 
also performing the rotational and/or torsional adjustment described and 
illustrated herein, then a curvilinear cut is produced in the proximal 
metaphysis of the patient's tibia, with the lower part of the cut being 
concave as viewed from the metaphysis. The cut is made generally 
perpendicular to the sagittal plane, thereby freeing a caudal, tibial 
portion within the metaphyseal region of the tibia for movement relative 
to the remaining portion of the tibia that includes the diaphysis of the 
tibia and the tibial crest. In this case, the invented bending step 
produces a tibial plateau leveling, as described in my referenced patent, 
as well as rotation of the thus-cut-separated tibial portions to produce a 
new fixed angular relationship therebetween. 
Briefly referring now to FIG. 6, which will be understood to be oriented 
consistent with the isometric views of FIGS. 1 through 4, the anatomical 
planes are illustrated schematically as dash-outlined rectangles labeled 
P.sub.S (representing the patient's sagittal plane) and P.sub.F 
(representing the patient's frontal plane) intersecting one another 
normally, or at a right angle, in a line of intersection indicated in FIG. 
6 by a dotted line. These planes are believed to be well understood by 
those of skill in the art, and are included for the sake of completeness 
and clarity. 
Accordingly, while a preferred embodiment of the invention has been 
described herein, and preferred methods associated therewith, it is 
appreciated that modifications are possible that are within the scope of 
the invention.