Laury Dahners Tricks for Percutaneous Fixation of Fractures
Metacarpals and metatarsals-
Distal Radius
A technique known as “buttress pinning”
can be useful in tubular, noncancellous
bone, especially the distal radius. The pin
is inserted into the fracture site and then
tilted so that it resists shear displacement,
then drilled through the opposite cortex.
This technique is for oblique, simple
fractures which are tending to displace one
way and just need to be pushed the other
direction – it isn’t good for truly unstable
fx.
Inserting such pins can be difficult. First, you use
fluoro to determine where the pin needs to be inserted
in the skin so that it will enter the bone at the fracture
site at the correct angle without “tenting” the skin too
much when you’re done. Lay the pin on the outside
and fluoro to get an alignment like in the figure
(overlying the fracture line) and draw a mark along
the pin. Poke the pin in percutaneously on that line.
Push it down to the fracture site by feel and fluoro.
Then “tent” the skin temporarily to bring the pin to an
angle that will allow you to insert it into the fracture
site.
Having worked the point of the pin into the fracture site,
tilt the pin back to the original angle (thus reducing the
fracture) and drive it into the opposite cortex.
This “buttress pin”
technique can also be used
to fix sheared off fragments
of metaphyseal cancellous bone though the technique is
not as necessary in this region.
Distal Humerus
When pinning a supracondylar humeral fracture in children,
I believe it is very important to insert your pins in the distal
fragment of the humerus before attempting the reduction.
This is because, when the elbow is flexed (as it almost has
to be while achieving a reduction), the ulnar nerve moves
medially, out over the tip of the epicondyle, where it is in
danger of having the pin inserted through it.
Therefore leave the
fracture malreduced
Ulnar nerve
and, with the elbow
extended (you’ll get
better fluoro spots like
this anyway), put your
pins in the medial and lateral epicondyles. Do this
on the AP view first, then check your lateral view. If
a pin isn’t where you want it on the lateral, don’t
take it out! Leave it in place and use it to guide you
in placing another one so that it is in the fracture site.
Now perform your reduction maneuver. I think what works
best is to apply traction and a little extension while looking
at the AP view on fluoro. When you have the medial and
lateral columns lined up on this view, push forward on the
olecranon (hard) and have someone advance the pins. Drive
them out the far cortex slightly. If they cross right at the
fracture site this is not satisfactory, as they will not prevent
rotation. But don’t take it all apart, just put in another
lateral pin that doesn’t cross the medial one in the same
place. If you have to change the medial pin for some
reason, remember to start it into the epicondyle with the
elbow extended.
Proximal Humerus
The surgical neck of the humerus can often be pinned or
screwed percutaneously.
Do not attempt to reduce the fracture and hold it while pinning
it. You may wish to confirm that you can reduce it before
inserting your pin, but this only makes sense if you would
then change to a different form of fixation upon opening the
fracture to obtain the reduction.
First, insert your pin in the distal fragment. Remember that the
humeral head is a posteromedial structure; so insert your pin
from the anterolateral surface (aimed posterolaterally) of the arm
(not from straight lateral, a common mistake). The elbow should
be facing anteriorly when you are starting your pin.
On the AP fluoro image it should strike the bone as shown, so
that it overlaps the shaft somewhat (if it appears to be directly on
the lateral surface it will slip off
posteriorly as you advance it
posteromedially.
Then advance the pin to the fracture site as shown on fluoro.
Now apply a reduction force, pushing the
shaft posteriorly and laterally with one
hand (or better pulling with a towel
looped around the upper arm as this will
keep your hand farther from the fluoro
beam).
When it is reduced, all you have to do is advance the pin to the
subchondral bone of the humeral head. Put in two more,
parallel to the first. Then put cannulated screws over them if
you like, or bend them and cut them off outside or under the
skin for removal at about 6 weeks.
Midshaft clavicle
Displaced midshaft clavicle fractures can frequently be percutaneously nailed using
antegrade “elastic titanium nails” (Nancy nails). Depending on the size of the patient
nails 2-3.5mm in diameter may be inserted. IF you are using the nails from Synthes it is
VERY helpful if you use a wire cutter to cut the hook off of the end of the nail as you can
put in a much larger nail if it doesn’t have a hook on the end (the hook nearly doubles the
diameter of the nail so that you can put in a 3.5mm nail without a hook in a clavicle that
would only hold a 2mm nail with a hook). In our study of patients treated for displaced
fractures nononperatively, with plates, with retrograde “Rockwood (modified Hagie)
pins”, with retrograde elastic nails and with antegrade elastic nails, the patients with the
elastic nails were the most satisfied group (nonops were least satisfied).
If this is unsuccessful towel clips may be used to percutaneously grasp the clavicle just
proximal and just distal to the fracture site, manually reducing the fracture before driving
the nail. If this is not successful a 2 cm incision over the fracture site can allow you to
directly grasp the fragments with Kocher clamps and reduce it. BE SURE to tilt the
fluoro 45 degrees cranial and caudal to get “orthogonal views” – DO NOT trust the AP
view alone. Once across the fracture site drive it until it is just beginning to make the turn
anterior at the end of the clavicle, then cut the nail at the skin level and use a tamp to
drive it down until it is barely palpable. The distal clavicle is very narrow and tight so
that the nail will be very firmly fixed in the small medullary canal distally and not prone
to migration (like nails and screws driven from distal to proximal into the patulous medial
clavicular medullary canal).
Having fixed a lot of clavicles with a lot of different methods, I strongly believe this is by
far the best technique. 1. It is safer because you are driving the nail away from the great
vessels 2. It is safe enough to try a closed nailing 3. Even if you have to open, the incision
can be smaller than a plate (or even the incision for a medially directed nail where you
must see well to be sure that you don’t accidentally drive the nail out of the medial
fragment into the great vessels) with a smaller scar and less injury to the supraclavicular
nerves. 4. The insertion incision can be very small and heals to look like a freckle 5. The
nail is tightly fixed in the distal clavicle and doesn’t back out 6. The tip of the nail is not
as irritating in the medial subcutaneous tissue as nails or screws protruding laterally into
the trapezius can be 7. Most patients do not require nail removal (most patients with
plates and Hagie screws do).
Femoral shaft (video at http://www.laury.dahners.com/orthoprofessional.html )
Place the patient in the lateral position on a radiolucent table. Be sure that male genitalia
is well anterior and not in the crotch. Drape the leg free and using a sterile distractor (the
same one used for hip arthroscopy http://www.m-p-r.com/hipdistractor.asp place the well
padded perineal post in the crotch and attach a k-wire bow at the knee. Allow the limb to
lie in about 450 flexion at the hip and knee (more hip flexion for subtrochanteric fx to
relax the iliopsoas and more knee flexion for distal fractures to relax the gastrocnemius).
Bring in the fluoroscope with the image
intensifier (big end) on top so that there
will be less magnification of the operative
femur. Lay a guide wire on top of the
femur, obtain an image and adjust the wire
until it lies over the femur, mark the skin
to show the location.
Put the pin in percutaneously to strike the upper end of the femur coaxially with the
medullary canal (Don’t worry about hitting the “piriformis fossa”. The piriformis fossa is
simply a palpable landmark that is usually coaxial with the canal which has been
traditionally been used for finding a starting point without using fluoro, it is not better
than using fluoro by any means). When you think you have a good location, strike the pin
with a mallet and shoot the other view. When you arc the c-arm for the cross-table AP
view, the unsterile tube end of it will pop up from under the table – don’t sterile drape it
as it is going to go right back down and get contaminated again, just shoot your image
and tilt it back immediately. Analyse your two views and, without taking out your first
guide pin, put in a second one in a better location. Repeat until you have a coaxial pin,
then use a knife to enlarge the pin hole into a 2 cm incision and use a reamer to open the
canal.
Insert your flexible guide wire for the reamer and thread it down to the fracture site. A
reduction tube or “finger” in the medullary canal of the proximal fragment may let you
line it up with the distal fragment to advance the wire but here are some other tricks. 1.
proximal fragment is anterior to the distal fragment in a proximal fracture – flex the
hip/distractor up to relax the iliopsoas and bring the distal fragment into alignment with
it. 2. proximal fragment is anterior to the distal fragment in a distal fracture – flex the
knee up to relax the gastrocs. 3. proximal fragment is medial – put a bump under it. 4.
distal fragment is medial – put a bump under it. 5. use a reduction wrench which you can
make out of parts from the overhead frame on a hospital traction bed.
Pediatric femur fracture
These can be nailed using elastic titanium nails and very small incisions.
Fluoro comes in from the opposite side of the table.
Flouro guidance is used to locate a 5-8mm incision directly in line with where you want
the nail to enter the bone.
Nails are inserted medially and laterally into the distal fragment and driven up to the
fracture site before reducing the fracture and driving them across.
Once the nails are across the fracture, stop with them4-5 cm short of where you want
them to finish in the proximal femur and cut them off at the skin surface. Drive them to
the depth you want them to be using the tamp in the set which has a little hollow at the
end.
These small incisions can make nail removal difficult because you cannot get pliers in
through them to grasp the nail. However, if you use the broken screw removal set from
Synthes, the nails can be retrieved through the same incisions. Simply open the old scar,
then spread down to the nail on fluoro and screw one of the left hand threaded broken
screw removal trumpets onto the end of the nail. The threads in the trumpet will bite into
the softer titanium with sufficient grip to pull the nail out. If necessary you can core over
nails that don’t protrude sufficiently from the bone using the reverse cutting hole saws
from that same set.
Percutaneous bone grafting
To insert bone graft through a small incision, prepare a syringe of appropriate size by
cutting off the end of the syringe barrel as shown below using a bone cutting forceps.
Remove the black rubber stopper from the end of the plunger (or it might catch on the
end of the syringe barrel when you push it though and be pulled off in the depths of the
wound).
Make a small, fluoro guided incision directly over the fracture site and insert the barrel of
the syringe. Pass a curette through the syringe and scrape the surfaces of the nonunion.
Pass an osteotome through the syringe and use it to “fish scale” the surface of the bone.
Pour bone grafting material into the barrel of the syringe (a Hibbs retractor makes a nice
“funnel” for this part of the procedure).
Use the syringe plunger or a tamp to push the bone graft material through the barrel of
the syringe and into the depths of the nonunion site. If you attempt to place bone graft
without the syringe in place much of the bone graft can be forced out into the
subcutaneous tissue and cause problems.