Between 1999 and 2004, one of us (D.R.) participated in the treatment of
eighteen consecutive patients with a fracture of the anteromedial facet of the
coronoid process (see Appendix). Fractures of the coronoid at the base
associated with posterior olecranon fracture-dislocation of the ulna (a
posterior Monteggia
injury14) are often
comminuted, and the anteromedial facet may be a separate
fragment15 (these
fractures were specifically excluded). Patients were invited to return for
evaluation with use of a protocol approved by our Human Research
Committee.
There were sixteen men and two women, with an average age of forty-nine
years (range, eighteen to eighty-five years). Eight patients had injured the
left arm (the dominant side in one patient), and ten patients had injured the
right arm (the dominant side in eight). The injury resulted from a fall from a
standing height (ten patients), a motor-vehicle accident (four patients), a
fall from a greater height (three patients, including one who fell from a
ladder; one, from a roof; and one, from a tree), and a fall while riding a
snowboard (one patient).
Four patients had injuries of the ipsilateral upper extremity, including
distal radial fractures in two patients (one of whom had a concomitant
fracture of the scaphoid), a perilunate fracture-dislocation in one patient,
and open fractures of the distal radial metaphysis and diaphysis, a fracture
of the scaphoid, and an acute carpal tunnel syndrome and forearm compartment
syndrome in one patient. Three patients had injuries of the contralateral
upper limb. Two patients had an injury of a lower limb. One patient had a
closed head injury.
Patterns of Injury
Several patterns of injury were observed in association with fracture of
the anteromedial facet of the coronoid process. These were separated into
fractures associated with either varus subluxation (thirteen patients) or
complete posterior dislocation of the elbow (five patients)
(Fig. 1).
Among the patients who had fractures associated with varus subluxation of
the elbow, seven had an associated avulsion of the lateral collateral ligament
from the lateral epicondyle (Fig. 1,
A); four had a fracture of the olecranon (with associated
avulsion of the lateral collateral ligament in one patient)
(Fig. 1, B); one had a
second, simple fracture at the base of the coronoid without fracture of the
olecranon (Fig. 1, C);
and one had an associated fracture of the medial lip of the trochlea (the
status of the lateral collateral ligament was unknown)
(Fig. 1, D).
Among the patients with complete dislocation of the elbow, two had very
small anteromedial facet coronoid fractures
(Fig. 1, E) and three
had an associated fracture of the radial head (a so-called terrible triad
injury1,2,16)
(Fig. 1, F).
Classification of the Coronoid Fractures
The coronoid fractures were evaluated with use of standard radiography in
all patients, computed tomography in nine patients (with three-dimensional
reconstructions in five), and operative exposure in fifteen patients. The
coronoid fractures were classified, according to the system of Regan and
Morrey12, as Type
II (a single or comminuted fragment that is more than just the tip, but
involving =50% of the coronoid process) in sixteen patients and as Type III
(a single or comminuted fragment involving >50% of the process) in two
patients. According to the classification system of O'Driscoll et
al.13, sixteen
patients had a Type-2 fracture (a fracture of the anteromedial facet of the
coronoid process), with one classified as Subtype 1; three classified as
Subtype 2, and thirteen classified as Subtype 3. Two patients had a Type-3,
Subtype-1 fracture (a fracture of the coronoid at its base). Among the
patients classified as having a fracture of the coronoid at its base, one had
separate anteromedial facet (Type 2) and base (Type 3) fractures and one had a
single large anteromedial facet fracture that included the sublime tubercle
(the insertion point of the anterior band of the medial collateral ligament),
which was classified as Type 3, Subtype 1, according to the system of
O'Driscoll et al., in which this fracture is considered a type of anteromedial
facet fracture13
(Fig. 2).
Treatment
Three patients were seen in referral after primary nonoperative treatment
elsewhere. Two had a terrible triad pattern of injury, and one had a minimally
displaced fracture of the anteromedial facet and a presumed avulsion of the
lateral collateral ligament. One patient with a terrible triad pattern of
injury was treated operatively two months after the injury with reconstruction
of the coronoid process with a fragment of the radial head, prosthetic
replacement of the radial head, reattachment of the lateral collateral
ligament to the lateral epicondyle, transposition of the ulnar nerve, and
hinged external fixation. Nonoperative treatment was continued in the
remaining two patients.
Three patients who were seen in referral after primary operative treatment
elsewhere included one patient with a lateral collateral ligament avulsion
only, one with a terrible triad injury pattern, and one with a concomitant
fracture of the medial aspect of the trochlea. A prior unsuccessful attempt
had been made to repair the anteromedial facet fracture with a single screw in
one patient; a second operation was performed by us to remove the loose screw.
In the other two patients, the coronoid fracture was not repaired at the time
of the original surgery and no additional surgery was performed by us.
Twelve patients were treated by us immediately after injury. Ten patients
had subluxation pattern injuries with lateral collateral ligament injury alone
in six, olecranon fracture in three (with associated lateral collateral
ligament avulsion in one), and a second fracture at the base of the coronoid
in one patient. Two patients had dislocation of the elbow with a very small
fracture of the anteromedial facet and tip of the coronoid. The coronoid was
repaired with a plate designed specifically for the anteromedial surface of
the coronoid (Acumed, Beaverton, Oregon) in seven patients (Fig.
3-A and 3-B,
3-C and 3-D,
3-E and 3-F), with a separate
3.0-mm cannulated screw (Synthes, Paoli, Pennsylvania) in three patients, with
a 2.0-mm T-shaped plate in two patients (combined with sutures in one), and
with sutures passed through drilled holes in one patient. The coronoid was not
repaired in the two patients with an elbow dislocation. Exposure of the
coronoid fracture was accomplished by mobilizing the ulnar nerve and
transposing it anteriorly and then developing the interval between the two
heads of the flexor carpi ulnaris where the nerve used to lie. In five
patients, a second muscular interval splitting the flexor-pronator mass more
anteriorly as described by Hotchkiss was
used17. In the two
patients with large fractures (O'Driscoll Type 3), the entire flexor-pronator
mass was elevated from the medial side of the ulna as described by Taylor and
Scham18. The three
olecranon fractures were repaired with plates designed specifically for the
proximal aspect of the ulna (Acumed) (Fig.
4-A,
4-B,
4-C). All lateral collateral
ligament injuries were reattached to the lateral epicondyle with one or two
metal G2 Mitek suture anchors with 2-0 Ethibond suture (DePuy Mitek, Norwood,
Massachusetts). For the two patients with an elbow dislocation and injury to
the medial collateral ligament, one ligament was reattached to the medial
epicondyle and one was not repaired. These were the only two patients treated
operatively in whom medial soft-tissue injury was encountered.
Patients treated by us were advised to avoid shoulder abduction (varus
stress on the elbow) for at least one month. Active-assisted elbow exercises
were initiated within one week of injury, at which point the postoperative
posterior splint was discarded. Resistive exercises were initiated six weeks
after injury.
Evaluation
Patients were evaluated according to the system of Broberg and
Morrey19. It is a
100-point system based on motion (40 points), strength (20 points), stability
(5 points), and pain (35 points). Pain is rated by the physician as follows:
none (35 points); mild with activity but no medication (28 points); moderate
with or after activity (15 points); and severe at rest, with constant
medication, and disabling pain (0 points). Categorical ratings were assigned,
with 95 to 100 points indicating an excellent result; 80 to 94 points, a good
result; 60 to 79 points, a fair result; and <60 points, a poor result.
One patient had an attempted elbow arthrodesis that failed to heal. The
result was counted as poor, and he was otherwise excluded from the final
analysis. Among the seventeen remaining patients, thirteen returned using a
protocol approved by our Human Research Committee for a comprehensive
interview, examination, and radiographs. One patient who had been last
evaluated four months after the injury and had declined to return specifically
for this study was included because the fractures were healed and his elbow
function was good and had been reaching a plateau when last seen. One patient
who had nearly full motion and no complaints four months after the injury was
living in another country at the time of a telephone interview three years
after the injury, and he reported that the elbow function continued to be
excellent. The two patients who could not be contacted had been seen more than
one year after the injury and were evaluated on the basis of the medical
record only. The average duration of follow-up for these seventeen patients
was twenty-six months (range, four to fifty-seven months).
Among these seventeen patients, the average arc of flexion and extension
was 116° (range, 30° to 145°) with average flexion of 133°
(range, 100° to 145°) and average flexion contracture of 17°
(range, 0° to 70°). The average arc of forearm rotation was 153°
(range, 90° to 170°) with average pronation of 76° (range, 70°
to 90°) and average supination of 80° (range, 70° to 85°). Two
patients, both treated elsewhere and seen in referral specifically for
problems related to the injury, had symptoms or signs referable to elbow
instability.
The average Broberg and Morrey score for these seventeen patients was 91
points (range, 70 to 100 points). Including the patient with a poor result
after a deep infection and subsequent attempted elbow arthrodesis, the results
were categorized as excellent in ten patients, good in two, fair in five, and
poor in one patient.
Complications and Additional Surgeries
Among the twelve patients whose initial surgery was performed by us, two
patients experienced complications leading to additional surgery within the
first few weeks. One patient had a deep infection that was treated with serial
débridement, including removal of loose implants, and parenteral
antibiotics. Chronic osteomyelitis developed, and he was eventually treated
with an attempted elbow arthrodesis that failed. His elbow function is similar
to that after a resection arthroplasty, and he was more satisfied at the time
of the latest follow-up than when the elbow had been arthrodesed. One patient
had recurrent dislocation of the elbow with a wound separation and a colonized
hematoma, which were treated with débridement, relocation of the elbow,
and hinged external fixation, leading to a good functional result.
Two patients had postoperative ulnar motor and sensory neuropathies, which
were thought to be due to the handling of or traction on the nerve. Both
patients were managed nonoperatively; one patient had persistent motor and
sensory nerve dysfunction two years after the injury, while the other patient
had complete resolution of the neuropathy over one year. One patient had
removal of a proximal ulnar plate that was causing symptoms. One patient had a
second procedure for release of an elbow contracture with heterotopic
ossification and a proximal radioulnar synostosis. He achieved a 95° arc
of elbow flexion and a 100° arc of forearm rotation.
Patients with Limited Treatment of the Anteromedial Facet Coronoid
Fracture
We separately analyzed the cases of the nine patients who, in retrospect,
were thought to have had limited treatment of the anteromedial facet and
compared them with those we thought had had secure fixation of the coronoid.
Among the nine patients with limited treatment of the coronoid fracture, three
were treated nonoperatively, four had not had the anteromedial facet addressed
intraoperatively, and two had somewhat tenuous fixation of the coronoid
fracture (a screw in one patient and a coronoid plate that may have been too
small in the other patient). The patient with a plate that was thought to be
too small was the one who also had a poor result after a deep infection. The
remaining eight patients had an average flexion-extension arc of 99°
(range, 30° to 140°), with an average flexion of 127° (range,
100° to 140°) and an average flexion contracture of 28° (range,
0° to 70°). Forearm rotation averaged 149° (range, 90° to
165°), with average pronation of 76° (range, 70° to 80°) and
average supination of 81° (range, 70° to 85°). The results were
rated excellent in three, fair in five, and poor in one patient. The average
score according to the rating of Broberg and Morrey (excluding the patient
with the failed arthrodesis) was 83 points (range, 70 to 100 points).
Including the patient with the failed elbow arthrodesis, seven of nine
patients with limited treatment of the coronoid fracture had problems with
elbow stability. Three patients had subluxation of the trochlea into the
defect in the anteromedial facet of the coronoid and arthrosis at the time of
the final follow-up (Fig. 5-A and
5-B). One patient had reconstructive surgery within three months
of the injury and obtained an excellent result. The two patients with complete
dislocation of the elbow with small anteromedial facet fractures that were not
repaired both had problems with elbow stability and required additional
surgery. One of them had redislocation of the elbow within a week of the
initial surgery and had a second operation with hinged external fixation,
ultimately achieving a fair result. The other patient had radiographic signs
of subluxation that corrected with active exercises of the elbow and avoidance
of shoulder abduction, and this patient later had a second operation to
address heterotopic bone. He also achieved a fair result.
Only two patients with limited treatment of the anteromedial facet fracture
of the coronoid did not have problems with instability and both were atypical.
They included the unusual patient with injury to the medial aspect of the
trochlea who had an excellent result after repair of the trochlear fracture
only and the patient seen a month after injury with a stable fracture and good
motion after nonoperative treatment.
Patients with Secure Fixation of the Anteromedial Facet Coronoid
Fracture
Among the nine patients with fractures of the anteromedial facet of the
coronoid that were thought to have secure fixation, the average arc of
flexion-extension was 131° (range, 108° to 145°), with average
flexion of 138° (range, 130° to 145°) and an average flexion
contracture of 7° (range, 0° to 22°). The arc of forearm rotation
averaged 157° (range, 140° to 170°), with average pronation of
77° (range, 70° to 90°) and average supination of 80° (range,
70° to 8v5°). Complications included postoperative ulnar neuropathies
due to traction on the nerve, which occurred in two patients and resolved in
both. Seven patients had an excellent result and two had a good result, with
an average score of 97 points (range, 90 to 100 points), according to the
system of Broberg and Morrey. None of these nine patients had symptoms or
signs referable to elbow instability.
Distinguishing fractures of the anteromedial facet of the coronoid process
from other types of coronoid fractures is of value because anteromedial facet
fractures are associated with (1) a distinct mechanism of injury (varus
posteromedial rotational rather than the more common posterolateral rotatory
injury force13),
(2) differences in associated injuries (radial head fracture and medial
collateral ligament injury are uncommon), and (3) differences in treatment (a
direct medial exposure and fixation of the coronoid is often necessary, most
frequently with a buttress plate). O'Driscoll et al. and Sanchez-Sotelo et al.
clearly identified this important fracture
characteristic9,13.
The recognition of an anteromedial facet fracture of the
coronoid13 as a
distinct and important type of coronoid fracture may make the Regan and Morrey
classification12,
which is based on fragment size alone, inadequate. The O'Driscoll
system13 is more
useful, but it may be even more important to identify the overall injury
pattern since this provides more information about what structures may be
injured and may benefit from
treatment15. In an
unpublished quantitative computed tomographic analysis, we found that the
entire coronoid process is translated medially with respect to the ulnar
metaphysis and diaphysis and that the anteromedial facet projects from the
medial surface of the ulna, making it vulnerable to injury. Although we
observed a variety of injury patterns associated with fractures of the
anteromedial facet of the coronoid, we believe that they are all caused by a
varus posteromedial rotational injury force. This distinguishes these injuries
from the majority of destabilizing elbow injuries, which seem to occur by
means of a posterolateral rotatory injury force that tears the lateral soft
tissues and then may fracture the radial head and coronoid (usually
transversely).
Our data suggest that inadequate fixation of this fracture contributes to
less optimal results. There are other differences between the group of
patients interpreted as having limited treatment of the anteromedial facet
fracture and the group interpreted as having secure fixation, such as the fact
that there were more dislocation injuries in the former than the latter group.
Our interpretation is that dislocation injuries were more likely to have
limited treatment of the coronoid fracture because the anteromedial facet
fracture was less likely to be appreciated or taken into account, and that
better treatment of the coronoid fracture will lead to better elbow function;
however, additional experience and additional data are needed to confirm this
impression.
On the basis of this experience, we recommend internal fixation of
fractures of the anteromedial facet of the coronoid process with use of a
medial exposure, even when the fracture is very small. Very small fractures
can be repaired with suture passed through drill-holes in the proximal aspect
of the ulna and engaging the anterior elbow capsule attached to the fragments.
An exposure through the split in the flexor carpi ulnaris where the ulnar
nerve runs provides effective exposure in most
cases13, but a more
anterior split of the flexor-pronator mass, as described by
Hotchkiss17, and a
more posterior elevation of the entire flexor-pronator mass, as described by
Taylor and Scham, may also be useful either alternatively or
concomitantly18. It
is not necessary to move the ulnar nerve in every case, and we have tried to
avoid doing so since the two ulnar nerve palsies in this series occurred in
nerves that had been mobilized and retracted. If the ulnar nerve is
transposed, we recommend retracting it anteriorly and suturing the skin to the
flexorpronator fascia temporarily to create an anterior pocket for the nerve
while the fracture is addressed, thereby avoiding excessive traction or
pressure from retractors or tapes placed around it. Computed tomography,
particularly three-dimensional reconstructions, has been useful to us in
preoperative planning.
A number of additional observations may assist with the management of
patients with varus posteromedial rotational pattern injuries. First, if the
elbow is not dislocated, the medial collateral ligament is usually intact.
Second, the lateral collateral ligament is avulsed from the lateral epicondyle
except in some patients who have a fracture of the olecranon or a second
fracture of the coronoid at its base. During operative exposure, the lateral
collateral ligament avulsion may not be apparent until the overlying fascia
has been incised. Finally, anteromedial facet injuries associated with a
complete elbow dislocation have both lateral collateral ligament and medial
collateral ligament injuries. The coronoid fracture can be subtle, and this
injury may be misinterpreted as a simple elbow dislocation (a dislocation
without associated fractures), but it can be much more difficult to manage. We
recommend repair of the medial collateral ligament and the lateral collateral
ligament as well as the coronoid fracture with its anterior capsular
attachments.
In conclusion, this review supports operative treatment of fractures of the
anteromedial facet of the coronoid in most patients. We believe that only
patients with a very small fracture, no subluxation of the elbow, and minimal
or no opening of the radiocapitellar joint with radiographs made while a varus
stress is applied will have acceptable results with nonoperative
treatment.
A table showing clinical information on all patients in the study is
available with the electronic versions of this article, on our web site at
(go to
the article citation and click on "Supplementary Material") and on
our quarterly CD-ROM (call our subscription department, at 781-449-9780, to
order the CD-ROM). ?