Exposure
The operation is performed with the patient in the supine position. A
sterile tourniquet is inflated only for dissection of the ulnar nerve, which
is transposed anteriorly. The TRAP (triceps-anconeus reflecting pedicle)
approach provides adequate exposure for a surgeon experienced with the
technique5. This
approach involves combining the Bryan-Morrey and modified Kocher approaches to
reflect the triceps in continuity with the anconeus. However, we believe that
an olecranon osteotomy provides even greater exposure and it is recommended in
the setting of intra-articular comminution.
Principle-Based Fixation Technique
We attempt to restore stability and function by achieving eight technical
objectives derived from the principles of (1) maximizing fixation in the
distal fragments and (2) ensuring that all fixation in the distal segment
contributes to stability at the supracondylar level. Six of these objectives
concern the screws in the distal fragments, and two concern the plates
(Table I)
(Fig. 1).
All eight of these objectives are achieved with the technique of what we
term parallel plating. The medial plate is placed on the medial aspect of the
medial column, and the lateral plate is placed laterally, rather than
posteriorly, on the lateral column. While we refer to the plates as being
parallel, each plate is actually rotated posteriorly slightly out of the
sagittal plane such that the angle between them is often in the range of
150° to 160°. This orientation permits the insertion of at least four
long screws completely through the distal fragments from one side to the
other. These screws interdigitate, thereby creating a fixed-angle structure
and greatly increasing stability of the construct. Contact between screws is
intended to enhance the locking together of the two columns. The plates must
be contoured to fit the geometry of the distal part of the humerus if
precontoured plates are not available. Locking screws were not used in this
series.
Interfragmentary compression is obtained between articular fragments as
well as at the metaphyseal level through the use of large bone clamps that
provide compression during the insertion of the screws attaching the articular
segment to the shaft. In the distal fragments, fully-threaded screws inserted
in this manner provide maximum thread purchase in the distal fragments.
Additional compression at the metaphyseal level results from slight
undercontouring of the plates and the use of dynamic compression holes in the
plates. The specific steps of the surgical technique are detailed below.
Step 1. Articular Surface Reduction
(Fig. 2)
Once the fracture is exposed, the first step is reassembly of the articular
surface. The proximal part of the ulna and the radial head can be used as a
template for the reconstruction of the distal part of the humerus. The
articular fragments are provisionally fixed with smooth Kirschner wires
(Fig. 2). In cases in which
there is extensive comminution, fine threaded wires (1 to 1.5 mm) are used and
then are cut off and left in as definitive adjunctive fixation. Kirschner
wires permit assembly of the joint surface fragments in a manner that is
analogous to the use of dowels in furniture making. It is necessary for these
wires to be placed close to the subchondral level so as not to interfere with
the passage of screws from the plates into the distal fragments; specifically,
no screws are placed in the distal fragments until the plates are applied.
The articular surface of the distal part of the humerus should be
reconstructed anatomically unless bone is missing. In the event of absent
bone, two important principles should be taken into consideration. First, the
anterior aspect of the distal part of the humerus is the critical region that
needs to be restored in order to have a functional joint; reconstruction of
the posterior articular surface of the distal part of the humerus is less
critical. Second, stability of the articulation requires the presence of the
medial half of the trochlea in combination with either the lateral half of the
trochlea or the capitellum; thus, the medial half of the trochlea is essential
for obtaining a stable and well-aligned joint.
Step 2. Plate Placement and Provisional Fixation
(Fig. 3)
The next step is to contour plates to fit the reassembled humerus medially
and laterally or to choose medial and lateral precontoured plates; one-third
tubular plates are not strong enough for fixation of these complex fractures.
The medial plate can be extended to the articular margin in cases of very
distal or comminuted fractures and is contoured to the shape of the medial
epicondyle. The ulnar nerve must be transposed if this extended plate is used.
Both plates should be slightly undercontoured to provide additional
compression at the metaphyseal region when applied. The length of the plates
is selected so that at least three screws can be placed in the proximal part
of the humeral shaft both medially and laterally proximal to the metaphyseal
component of the fracture. Ideally, the plates should end at different levels
proximally to avoid the creation of a stress-riser. The plates are then
provisionally applied according to the following steps.
First, two smooth 2.0 to 2.5-mm Steinmann pins are introduced at the medial
and lateral epicondyles through holes in the plates while they are held
accurately against the bone. These pins are left in place until after step 4
(described below). The pins create pilot holes for later replacement with
screws, are easy to drill around, and do not interfere as much with the
placement of the two distal screws as would be the case if they were replaced
by screws earlier.
Second, the appropriate reduction of the distal fragments to the humeral
shaft at the supracondylar level is confirmed.
Third, one cortical screw is loosely introduced into a slotted hole to
secure each plate in place; the use of slotted holes facilitates later
adjustments in plate position.
Step 3. Articular Fixation
(Fig. 4)
Once the plates have been provisionally applied, medial and lateral screws
are introduced distally to provide stable fixation of the intra-articular
fragments and rigid anchorage to the plates. The two distal screws, one medial
and one lateral, are inserted with use of a targeted drill-guide. As stated
above, the screws should be as long as possible, should pass through as many
fragments as possible, and should engage in the opposite column. Prior to
screw insertion, a large bone clamp is used to compress the intra-articular
fracture lines unless there is a gap in the articular surface. This ensures
interfragmentary compression without the need for lag screws.
Step 4. Supracondylar
Compression
(Figs. 5-A and
5-B) The plates are then fixed proximally
under maximum compression at the supracondylar level.
First, the slotted proximal screw on one side is backed out and a large
bone clamp is applied distally on that side and proximally on the opposite
cortex to eccentrically load the supracondylar region. A second proximal screw
is inserted through the plate in compression mode, and then the screw in the
slotted hole is retightened. Care should be taken not to change the
varus-valgus or rotational alignment of the articular surface when the bone
clamps are applied.
Second, the same steps are followed on the opposite side. Following this
step, the fixation should be quite stable.
Third, diaphyseal screws are then introduced, providing additional
compression as a result of the undercontoured plates being pulled down to the
underlying bone. To avoid having the screws strip the bone, this last step is
best performed by squeezing the plates against the bone with a large clamp
rather than relying on the screws to deform the plates.
Step 5. Final Fixation
(Fig. 6)
The smooth Steinmann pins are removed, and the remainder of the screws are
inserted. The intraoperative elbow motion should be full unless substantial
swelling has already developed. One deep and one subcutaneous drain are placed
during the closure. The skin should be closed with staples or interrupted
sutures.
Dealing with Metaphyseal Bone Loss
Adequate osseous contact with interfragmentary compression in the
supracondylar region is necessary to ensure the stability of the construct and
eventual fracture union. If metaphyseal bone loss or comminution precludes an
anatomic reconstruction with satisfactory osseous contact, the humerus can be
shortened at the metaphyseal-diaphyseal fracture site, provided that the
overall alignment and geometry of the distal part of the humerus is correct.
We refer to this alternative reconstructive technique as supracondylar
shortening (Fig. 7). This
technique is especially useful in cases of combined soft-tissue and bone loss.
Shortening by =1 cm has only a slight effect on triceps strength in
terminal extension6,
and in cases of severe soft-tissue and bone loss, as much as 2 cm of
shortening can be tolerated without serious disturbance of elbow
biomechanics6.
Immediately after wound closure, the elbow is placed in a bulky
noncompressive Jones dressing with an anterior plaster slab to maintain full
extension, and the upper extremity is kept elevated. The initial
rehabilitation is planned according to the extent of soft-tissue damage.
Fractures that are associated with severe soft-tissue damage, which include
most open fractures and high-energy closed fractures, are immobilized and
elevated in elbow extension for three to seven days postoperatively. Closed
fractures without severe swelling or fracture blisters are removed from the
Jones dressing after two days, and a nonconstrictive elastic sleeve is applied
over an absorbent dressing that is placed on the wound. A physical therapy
program that includes active and passive motion is then initiated. All
patients are permitted active use of the hand and are instructed not to lift
(or push or pull) anything heavier than a glass of water or a telephone
receiver for the first six weeks. No form of external protection such as casts
or braces is used.
If postoperative motion fails to progress as expected, a program of
patient-adjusted static splinting is instituted as soon as the soft tissues
are healed. Eight of the elbows in this study were treated with such a
program, which was commenced after the third or fourth week. The torque across
the elbow that was applied with such a patient-adjusted splint was low enough
to cause discomfort but not pain and therefore was not of concern with regard
to the security of the fracture fixation.
Neither hardware failure nor fracture displacement occurred in any patient,
and primary union was achieved at the sites of thirty-one of thirty-two
fractures.
CRITICAL CONCEPTSThe critical concept being presented here is the idea that stability of the
distal part of the humerus is achieved by the creation of an architectural
structure. The bone fragments rely on their integration with the structure,
rather than on fixation by screw threads, for stability. The concept is
borrowed from architectural concepts and the application of civil engineering
principles to surgery. The interdigitation of screws within the distal segment
rigidly attaches the articular fragments to the shaft by linking the two
columns together. This permits stability to be achieved in cases of injuries
such as low transcondylar fractures (Figs.
8-A through 8-D) or severely comminuted fractures
(Figs. 9-A through 9-D).The concept follows the architectural principles of an arch, in which two
columns are anchored at their base (on the shaft of the humerus) and are
linked together at the top (long screws from the plates on each side
interdigitating within the articular segment). The interdigitation is best
achieved by contact between the screws. However, multiple screws separated by
small gaps within the bone will function as a "rebar" (steel rods
inside concrete)-type construct. Fixation of the bone fragments is thus
reliant not on screw purchase in the bone but on the stability of the hardware
framework, in just the same way in which a modern building derives its
stability from the gridwork of steel assembled and bolted or welded together
inside its walls and columns.The screws in the distal segment are converted into fixed-angle screws by
two of the technical objectives. First, several long screws in the distal
fragments lock together by means of interdigitation. Second, these screws pass
through a plate on one side and into a bone fragment on the other side that is
itself also anchored by a plate. From an engineering perspective, this
technique of creating fixed-angle screws enhances fixation in the distal
fragments. It also permits rigid linkage and compression between the distal
segment and the shaft. The combined use of clamps, strong and slightly
undercontoured plates, dynamic compression holes, and selected metaphyseal
shortening provides interfragmentary compression at the supracondylar level.
The stability of the construct is such that a rehabilitation program can be
commenced in the immediate postoperative period without fear of hardware
failure.INDICATIONS:The indications for parallel-plate fixation include intercondylar and
supracondylar fractures and nonunions of the distal part of the humerus,
particularly those that are associated with comminution and/or bone loss. This
technique can also be used to fix distal humeral osteotomies.CONTRAINDICATIONS:Provided that there are no contraindications to internal fixation or
surgery on the elbow in general, we have not experienced specific
contraindications to the use of the parallel plating technique for the
treatment of distal humeral fractures or nonunions.PITFALLS:One pitfall to avoid is the placement of a free screw into the distal
fragments prior to the application of a plate. Such a screw does not
contribute to supracondylar stability (principle 2) and is not as secure as it
might have been if it had passed through a plate (principle 1). It also
potentially interferes with the passage of the screws through the plate into
the distal articular segment. Another pitfall is the inappropriate placement
of Kirschner wires for provisional fixation. These wires should be placed in
the subchondral region rather than in the center of the articular segments
where the screws will go. They also need to be placed where they will not
interfere with the plates. Anticipating where the plates will be positioned on
the bone before placing the temporary Kirschner wires avoids this problem.
Some surgeons experience difficulty with placement of the distal articular
screws through the plates and across to the other side without violating the
joint or the olecranon fossa. This maneuver is facilitated by the use of a
targeted drill-guide and by waiting to replace the 2 or 2.5-mm Steinmann pins
in the distal articular segments until after having placed at least one screw
through a second hole of each plate. These pins reserve a pathway for screws
to be placed across the distal segment from each side. They also are easy to
drill past and to place a screw past, whereas if they are replaced by screws
immediately, the subsequent drilling is rendered more difficult by the
larger-diameter screw. Moreover, when drilling through the distal segment, a
drill-bit may be prone to hitting a screw and breaking. This problem can be
avoided by drilling backward or by drilling with a smooth Steinmann pin; the
pin will tend to deflect off a screw rather than break.With respect to the soft tissues, a common pitfall and misunderstanding is
the assumption that the technique of parallel plating requires additional
soft-tissue stripping. While the lateral skin flap must be raised around to
the lateral supracondylar ridge and the lateral epicondyle, there is no
additional stripping of the deep soft tissues from the lateral column compared
with traditional plating of a distal humeral fracture. In all circumstances,
the soft tissues should be retained on the articular fragments.Excessive contouring of the distal end of the lateral plate can cause
entrapment of the common extensor origin and/or lateral collateral ligament
complex. This can result in loss of motion and even necrosis of the underlying
soft tissues. This is avoided by placing the plate such that it stops at the
epicondyle rather than distal to it and by ensuring that the plate does not
wrap around the epicondyle and compress the soft tissues. This will give the
appearance on the postoperative radiograph of the tip of the plate sitting
away from the bone, but this space is required to accommodate the soft tissues
under the plate.AUTHOR UPDATE:Subsequent to the publication of the original article, a few changes have
been made. We now routinely use precontoured plates rather than bending
generic plates. While locking plates are available, we prefer to use
variable-angle locking screws for the distal segment to prevent the problem of
incorrect screw positioning due to the fixed angles predetermined by plate
design. With the use of locking screws, fewer screws are likely to be
necessary, and we routinely place four locking screws (two from each side) in
the distal segment.Finally, we have come to believe that resting the soft tissues for a
minimum of three days after surgery decreases the physiologic response to
trauma compared with starting mobilization one or two days after surgery.
Therefore, we place the arm in a padded Jones dressing with an anterior
plaster slab to maintain the elbow elevated in an extended position for three
days after surgery. It is taken down from the elevated position once or twice
an hour for a few minutes to relieve the shoulder and to prevent perfusion
disturbance.
CRITICAL CONCEPTS
The critical concept being presented here is the idea that stability of the
distal part of the humerus is achieved by the creation of an architectural
structure. The bone fragments rely on their integration with the structure,
rather than on fixation by screw threads, for stability. The concept is
borrowed from architectural concepts and the application of civil engineering
principles to surgery. The interdigitation of screws within the distal segment
rigidly attaches the articular fragments to the shaft by linking the two
columns together. This permits stability to be achieved in cases of injuries
such as low transcondylar fractures (Figs.
8-A through 8-D) or severely comminuted fractures
(Figs. 9-A through 9-D).
The concept follows the architectural principles of an arch, in which two
columns are anchored at their base (on the shaft of the humerus) and are
linked together at the top (long screws from the plates on each side
interdigitating within the articular segment). The interdigitation is best
achieved by contact between the screws. However, multiple screws separated by
small gaps within the bone will function as a "rebar" (steel rods
inside concrete)-type construct. Fixation of the bone fragments is thus
reliant not on screw purchase in the bone but on the stability of the hardware
framework, in just the same way in which a modern building derives its
stability from the gridwork of steel assembled and bolted or welded together
inside its walls and columns.
The screws in the distal segment are converted into fixed-angle screws by
two of the technical objectives. First, several long screws in the distal
fragments lock together by means of interdigitation. Second, these screws pass
through a plate on one side and into a bone fragment on the other side that is
itself also anchored by a plate. From an engineering perspective, this
technique of creating fixed-angle screws enhances fixation in the distal
fragments. It also permits rigid linkage and compression between the distal
segment and the shaft. The combined use of clamps, strong and slightly
undercontoured plates, dynamic compression holes, and selected metaphyseal
shortening provides interfragmentary compression at the supracondylar level.
The stability of the construct is such that a rehabilitation program can be
commenced in the immediate postoperative period without fear of hardware
failure.
INDICATIONS:
The indications for parallel-plate fixation include intercondylar and
supracondylar fractures and nonunions of the distal part of the humerus,
particularly those that are associated with comminution and/or bone loss. This
technique can also be used to fix distal humeral osteotomies.
CONTRAINDICATIONS:
Provided that there are no contraindications to internal fixation or
surgery on the elbow in general, we have not experienced specific
contraindications to the use of the parallel plating technique for the
treatment of distal humeral fractures or nonunions.
PITFALLS:
One pitfall to avoid is the placement of a free screw into the distal
fragments prior to the application of a plate. Such a screw does not
contribute to supracondylar stability (principle 2) and is not as secure as it
might have been if it had passed through a plate (principle 1). It also
potentially interferes with the passage of the screws through the plate into
the distal articular segment. Another pitfall is the inappropriate placement
of Kirschner wires for provisional fixation. These wires should be placed in
the subchondral region rather than in the center of the articular segments
where the screws will go. They also need to be placed where they will not
interfere with the plates. Anticipating where the plates will be positioned on
the bone before placing the temporary Kirschner wires avoids this problem.
Some surgeons experience difficulty with placement of the distal articular
screws through the plates and across to the other side without violating the
joint or the olecranon fossa. This maneuver is facilitated by the use of a
targeted drill-guide and by waiting to replace the 2 or 2.5-mm Steinmann pins
in the distal articular segments until after having placed at least one screw
through a second hole of each plate. These pins reserve a pathway for screws
to be placed across the distal segment from each side. They also are easy to
drill past and to place a screw past, whereas if they are replaced by screws
immediately, the subsequent drilling is rendered more difficult by the
larger-diameter screw. Moreover, when drilling through the distal segment, a
drill-bit may be prone to hitting a screw and breaking. This problem can be
avoided by drilling backward or by drilling with a smooth Steinmann pin; the
pin will tend to deflect off a screw rather than break.
With respect to the soft tissues, a common pitfall and misunderstanding is
the assumption that the technique of parallel plating requires additional
soft-tissue stripping. While the lateral skin flap must be raised around to
the lateral supracondylar ridge and the lateral epicondyle, there is no
additional stripping of the deep soft tissues from the lateral column compared
with traditional plating of a distal humeral fracture. In all circumstances,
the soft tissues should be retained on the articular fragments.
Excessive contouring of the distal end of the lateral plate can cause
entrapment of the common extensor origin and/or lateral collateral ligament
complex. This can result in loss of motion and even necrosis of the underlying
soft tissues. This is avoided by placing the plate such that it stops at the
epicondyle rather than distal to it and by ensuring that the plate does not
wrap around the epicondyle and compress the soft tissues. This will give the
appearance on the postoperative radiograph of the tip of the plate sitting
away from the bone, but this space is required to accommodate the soft tissues
under the plate.
AUTHOR UPDATE:
Subsequent to the publication of the original article, a few changes have
been made. We now routinely use precontoured plates rather than bending
generic plates. While locking plates are available, we prefer to use
variable-angle locking screws for the distal segment to prevent the problem of
incorrect screw positioning due to the fixed angles predetermined by plate
design. With the use of locking screws, fewer screws are likely to be
necessary, and we routinely place four locking screws (two from each side) in
the distal segment.
Finally, we have come to believe that resting the soft tissues for a
minimum of three days after surgery decreases the physiologic response to
trauma compared with starting mobilization one or two days after surgery.
Therefore, we place the arm in a padded Jones dressing with an anterior
plaster slab to maintain the elbow elevated in an extended position for three
days after surgery. It is taken down from the elevated position once or twice
an hour for a few minutes to relieve the shoulder and to prevent perfusion
disturbance.