THE ELECTRO-OSTEOTOME. 
A New Instrument for the Performance of the Operation 
of Osteotomy. 
MILTON JOSIAH KOBERTS, M.D., 
PROFESSOR OF ORTHOPEDIC SURGERY AND MECHANICAL THERAPEUTICS IN THE NEW YORK 
POST-GRADUATE MEDICAL SCHOOL; VISITING ORTHOPEDIC SURGEON TO 
THE CITY HOSPITALS ON RANDALL*S ISLAND, ETC. 
Granting that surgeons, especially of late, have too frequently 
resorted to operative procedures for the relief of bony defor- 
mities ; that they have shown a disinclination to adopt the 
more judicious, safe, and rational treatment by means of 
suitably constructed orthopedic apparatus, there is never- 
theless a large and diversified class of cases which can only 
be successfully dealt with by operative interference. Many 
patients suffering from bony deformities that would have been 
amenable to mechanical treatment in their early stages come 
under the observation of the surgeon too late in life to avoid 
an operation. Again, in general hospitals and ambulatory 
clinics, where we have to do even with young subjects, the 
expense of orthopedic apparatus and the necessarily long 
continuance of mechanical treatment to effect a cure, may 
deprive the patient of therapeutic measures which would be 
adopted in private practice, thereby relegating his destinies to 
the domain of osteotomies. 
It therefore becomes the subject of legitimate inquiry as to 
the best means of performing these operations. 
It is not the purpose of this communication, however, to 
review the various operations of Mayer, Annandale, Barton, 
Adams, Ogston, Barwell, Beeves, Macewen, and other surgeons; 
nor to discuss in detail the merits and demerits of the tools 
which have been used by operators other than myself. I wish 
simply to call attention to an instrument which, in my opinion, 
in a large range of cases possesses important advantages 
over any that have hitherto been employed. This conclusion 
has been reached after a sufficiently extended and varied 
personal experience from which to make deductions. 2 
The instruments used by surgeons in the operation of oste- 
otomy* may all be classified under the following heads: 
1. Chisels. 
2. Cutting forceps or nippers. 
3. Shears. 
4. Gimlets. 
5. Drills. 
6. Saws. 
Of these instruments the saw possesses the superior 
qualities of rapidity, certainty, and evenness of cut. Further- 
more, by its use the concussion and shock incident to the 
employment of the chisel and mallet, are entirely avoided. 
Why then do surgeons ever resort to the use of chisels, drills, 
etc.? The reasons are as follows : 
First, as to the use of the long or straight saw. Though 
admirably adapted to the direct application of hand power, 
its to-and-fro movements render it hazardous to the soft parts 
under many circumstances. This objection, however, has 
been very successfully overcome in that form of the instru- 
ment devised by Dr. George F. Shrady, in which the blade 
is operated through a protecting metallic sheath. His saw is 
very narrow, and was especially designed for simple subcu- 
taneous transverse section of bone. Another objection to the 
straight saw is the impossibility of executing to - and - fro 
movements in certain situations. Moreover, it is not well 
adapted to the removal of cuneiform segments from bone 
deeply imbedded in the soft parts. And, finally, it is, for the 
most part, impracticable to use it in making longitudinal cuts. 
I pass in review the objections to the use of the hollow 
(trephine) and chain saws, which must be patent to all. 
The circular saw, though equally well suited in form to the 
removal of transverse wedges of bone and the making of 
longitudinal cuts, and not open to the objection of to-and-fro 
movements, has never been extensively employed by surgeons. 
The reasons for its disuse lie, then, not in its form, nor in its 
rotary movement. Carrying our inquiry a little further, 
however, they become evident. Paramount among these is 
the impossibility of a direct application of hand-power to the 
♦ The word is here used in its broadest signification. 3 
evolution of the rotary motion of the circular saw. If manual 
power be used at all, some mechanism is necessary in order 
to develop rotation of the blade. 
Two difficulties present themselves in the adaptation of 
hand-power to driving the circular saw. One of these is the 
disadvantage with which force is applied at the axis of motion 
to overcome resistance at the peripheral margin. The other 
is the rapidity of rotation necessary to effective work. If the 
problem were the construction of a hand machine to rotate a 
circular blade meeting with no resistance at its periphery, 
nothing would be more simple. Or, if power could be applied 
at the margin of the blade to overcome resistance at the axis 
of motion, the device of such a machine would still be a very 
simple mechanical problem. It is, then, the great resistance 
which the serrated edge meets when in contact with bone, 
and the necessity of overcoming this by power applied to the 
arbor of the blade that make the task of construction and 
propulsion so difficult. 
A number of ingenious inventions have been offered, but 
when put to the test of sawing bone on the living subject 
have not answered in practice what they promised in specu- 
lation. As a rule their blades have been placed at a right 
angle with the main shaft, and, on this account, have been 
difficult to hold in position. They have, without exception, 
been deficient in power or speed, or both. Of the hand and 
foot-motors which have been devised for driving circular saws, 
that which is ordinarily used for dental purposes is the most 
complete in its workmanship and satisfactory in its execution. 
But the blades of these saws are of too small diameter to 
frequently be of service to the surgeon, and the engines and 
gearing which drive them are not built of sufficient strength 
to admit of the employment of larger saws. In concluding 
the adduction of objections to the circular saw it is necessary 
to state that surgeons have always experienced great difficulty 
in protecting the soft parts while using it. 
From what has been said it will be seen that in order to 
produce an osteotome of superior excellence to any we now 
have, it must be capable of dividing any bone in the human 
body, from the smallest to the largest, such division to be 
rapid, smooth, and certain, even though it be of the hardest 
bone; the blade of the instrument should readily follow the 
direction given it by the surgeon ; it should be adapted to simple, cuneiform, and longitudinal osteotomies in any situ- 
ation, of easy manipulation and imparting to the hand of the 
surgeon all the sensations that could be appreciated with a 
probe ; possessing strength and portability, and not likely to 
get out of order ; and, finally, capable of being used without 
danger to the soft parts. 
Such an instrument is illustrated in Fig. 1, from a photo- 
graph. It is here represented as it appears when suspended 
Fig. 1. 
and grasped by the hand of the surgeon ready for action. 
It consists of a small electro-motor actuated, through insulated 
wires, by a powerful battery and carrying a circular saw that 
revolves in a plane parallel with that of the central shaft. A 5 
hollow cylinder with a collar-like base is firmly screwed to the 
end plate of the motor and forms the handle of the instru- 
ment. Upon this a soft-rubber hand-piece, fashioned like 
that of a carpenter's chisel, is slipped and fastened in position; 
an arrangement which adds security to the surgeon's grip 
when operating. The central shaft of the motor is continuous 
through the hollow hand-piece. At its distal end, a right-angle 
miter-gearing connects it with the saw-bearing pivot. A me- 
tallic shield guards the proximal aspect of the serrated blade. 
Shields are provided for each size of saw. The depth of cut 
which it is possible to make with a given saw of course 
depends upon the diameter of the blade, being a trifle less 
than the distance from the centre to the periphery. The direc- 
tion of the kerf, however, can be so modified as to enable the 
operator to easily divide a bone having a greater diameter 
than half that of the saw he is using. 
The saws which I now use have been constructed with great 
care in accordance with my directions. Prior to their adoption 
I made extended experiments with many forms and sizes of 
teeth and thicknesses of blade. In order to adapt the saw to 
the requirements of individual cases, I have thus far found it 
desirable to have four sizes, viz.: 32 (li inch), 41 (If inch), 51 
2 inches), and 63 (2i inches) millimeters in diameter. The 
teeth are coarse in proportion to the size of the saw, and num- 
ber 18, 16, 14, and 12, respectively, per linear inch (25 min.). 
These saws are so ground as to gradually diminish in thickness 
from the periphery to the centre. Binding in the kerf, when 
making deep cuts, is thus prevented. If the blade be made of 
the same thickness throughout, the side friction will be so great 
that the motor will be unable to drive the saw with adequate 
force and speed after it has fairly entered the bone. Provision 
is still further made for increasing the width of the kerf over 
that of the saw by giving to the teeth a little “ set.” This 
latter procedure is a very delicate operation and requires con- 
siderable mechanical skill to do it properly. It is important 
that the alternate lateral inclination of the teeth should be 
perfectly regular throughout; otherwise, the smooth and easy 
cutting of the saw will be interfered with. In form, the 
serrations are slightly raked instead of hooked. They are so 
filed that their cutting edge is at a right angle with the blade, 
instead of being at an oblique angle, as in most circular saws. 
The blades are made of the best steel and have a special 6 
spring temper. They are not so hard as those used in cutting 
iron or brass, nor are they so soft as those used in cutting 
wood. Saws tempered for metal work, are too brittle for saw- 
ing bone; they would be apt to snap in the kerf, should the 
operator permit any lateral deviation of the blade. Tempered 
for sawing timber, the teeth would soon become dull by con- 
tact with hard bone. Lastly, great pains is taken to have the 
blades of the saws absolutely free from “ buckle ” or twist. 
This is necessary in order that they shall run perfectly true 
and not bind in the kerf. 
Upon the plate at the opposite end of the motor from that 
to which the hand-piece is attached are two binding-posts, 
which receive the ends of the electrodes connecting the insti'U- 
ment with the battery. Considerable experimenting was neces- 
sary in order to determine upon a form of battery having suf- 
ficient duration and power without unnecessary bulk. A 
general idea of the battery which I use can be gained from 
Fig. 2. It is a zinc carbon battery. The cells are of glass and 
ten in number. Their dimensions are 2x7x8 inches. Each 
cell contains one zinc plate 6x8 inches, placed between two 
carbon plates of equal size. The fluid used is a solution of bi- 
chromate of potassium, known as red acid, somewhat stronger 
than that used in the ordinary faradic batteries. The duration 
of maximum power furnished by this battery is from twenty 
to twenty-five minutes, sufficient time for the performance of 
any number of osteotomies which the surgeon will ever be 
called upon to do at one sitting. The battery is only permitted 
to be in action during the brief periods required for making 
sections of bone. The zinc and carbon plates are firmly fas- 
tened to a board which is suspended above the glass cells by 
means of coiled springs, as shown in the cut. A lever at the 
side of the battery-box furnishes the means of submerging 
the plates in the fluid at pleasure, by simply depressing it. 
Upon releasing the lever the plates are automatically drawn 
out of the fluid by the action of the springs. Conservation 
of battery power is thus made perfectly feasible, for as soon 
as the surgeon has made a simple or cuneiform section of 
bone, the lever can be released and the further working of the 
battery prevented until he is again ready for action. In trans- 
portation the fluid is emptied from the cells. The framework 
which serves for the suspension of the plates is so constructed 
that it can be quickly taken apart and laid in the battery-box 7 
on top of the board to which the plates are fastened. This 
arrangement makes the battery very compact and readily 
transportable. 
Fig. 2. 
When using the electro-osteotome, it is suspended by a 
solid rubber cord, six or seven millimeters in diameter, from 
the cross-bar of an adjustable crane screwed to the edge of 
the operating-table. In this way all weight is removed from 
the hand of the surgeon, and leaves the instrument as 
thoroughly at his command as would be the most delicate 
probe. 
The high rate of speed (about six thousand revolutions per 
minute) and the great force with which the saw is driven, ne- 
cessitates skillful manipulation and great vigilance on the part 
of the operator in using the osteotome. The limb of the patient 
should be firmly held by an assistant, and the precise direction 
and extent of the cut determined upon before permitting the 
first impact of the blade against the bone. The keen eye and 
sense of touch of a skillful surgeon will readily appreciate 
whether there is any departure from the predetermined line 
of incision, or binding of the blade in the kerf. 8 
And now as to the means of protecting the soft parts. Fig. 
3 represents one form of protecting retractor, which I use in 
osteotomy operations. It was made for me by Messrs. Stohl- 
mann, Pfarre & Co., and its form is specially adapted to the 
Fig. 3. 
supracondyloid operation for genu valgum. Two such instru- 
ments as is here represented form a pair. They are intro- 
duced one at a time through the linear incision in the soft 
parts, carried down to the bone and passed around it, much 
after the fashion of applying obstetric forceps. When in posi- 
tion they are pressed apart so as to make room for the blade 
of the osteotome. By their use there is no possibility of injur* 
ing any of the soft tissues while operating. The retractors are 
provided with a double curve at each end, one large, the other 
small, so as to adapt them to large and small bones 
In conclusion I may say, in illustration of the labor and 
time saving qualities of the electro-osteotome, that in opera- 
ting for double knock-knee and bow-legs, I have removed 
wedges of bone in from thirty seconds to one minute that 
would require from fifteen to thirty minutes to chisel out. The 
incision made with the saw is clean, the severed ends of the 
bone are not comminuted, and the two cut surfaces can be 
readity and perfectly coaptated. 
The mechanical details connected with the perfection of the 
instruments and battery above described have been very nu- 
merous, vexatious and at times discouraging. In prosecuting 
this work I have been the recipient of many courtesies at the 
hands of Mr. Edward P. Suter, of the Electro-Dynamic Co., 
Messrs. Wait & Bartlet, and the Western Electric Co., all of 
this city. 
105 Madison Avenue.