Abstract
Background: Surgical treatment of forearm deformities in patients
with multiple cartilaginous exostoses remains controversial. The purpose of
the present study was to determine the reasonable indications for operative
treatment and to evaluate long-term results of forearm surgery in these
patients.
Methods: We retrospectively reviewed twenty-three patients
(thirty-one forearms) after a mean duration of follow-up of nearly thirteen
years. The mean age at the time of the initial procedure was eleven years. The
patients underwent a variety of surgical procedures, including excision of
exostoses; corrective procedures (lengthening of the radius or ulna and/or
corrective osteotomy of the radius and/or ulna) and open reduction or excision
of a dislocated radial head. Clinical evaluation involved the assessment of
pain, activities of daily living, the cosmetic outcome, and the ranges of
motion of the wrist, forearm, and elbow. The radiographic parameters that were
assessed were ulnar variance, the radial articular angle, and carpal slip.
Results: Four patients had mild pain, and five patients had mild
restriction of daily activities at the time of follow-up. Eight patients
stated that the appearance of the forearm was unsatisfactory. Radiographic
parameters (ulnar variance, radial articular angle, carpal slip) were
initially improved; however, at the time of the final follow-up visit, the
deformities had again progressed and showed no significant improvement. The
only procedure that was associated with complications was ulnar lengthening.
Complications included nonunion (three forearms), fracture of callus at the
site of lengthening (two forearms), and temporary radial nerve paresis
following an ulnar distraction osteotomy (one forearm). Excision of exostoses
significantly improved the range of pronation (p = 0.036).
Conclusions: In our patients with multiple cartilaginous exostoses,
corrective osteotomy and/or lengthening of forearm bones was not beneficial.
The most beneficial procedure was excision of exostoses. Reasonable
indications for forearm surgery in these patients are (1) to improve forearm
rotation and (2) to improve the appearance.
Level of Evidence: Therapeutic Level IV. See Instructions
to Authors for a complete description of levels of evidence.
Multiple cartilaginous exostoses, also known as multiple osteochondromata
or diaphyseal aclasis, are characteristic of a disorder of endochondral bone
growth that features abnormal metaphyseal bone prominences capped with
cartilage, which are accompanied by defective metaphyseal remodeling and
asymmetrical retardation of longitudinal bone growth. Forearm deformities are
seen in 30% to 60% of patients with multiple
exostoses1-4.
The most common deformities are a combination of relative shortening of the
ulna, bowing of either or both forearm bones, increased ulnar tilt of the
distal radial epiphysis, ulnar deviation of the hand, progressive ulnar
translocation of the carpus, and dislocation of the head of the
radius5-10.
The treatment of forearm deformities in these patients is difficult because
the long-term results have not been well documented, and there is a lack of
consensus regarding the indications for surgery. The present study was
performed because the long-term prognosis after operative intervention is
uncertain. In addition, we attempted to define reasonable indications for the
operative management of these patients.
Fifty patients were diagnosed as having multiple cartilaginous exostoses at
Osaka University Hospital and Osaka Minami Medical Center between 1962 and
2000. In this group, thirty-four patients (forty-two forearms) had surgical
treatment. We attempted to contact the patients who had already reached
skeletal maturity (i.e., those who were at least eighteen years old). As a
result, twenty-three patients (thirty-one forearms) were successfully
contacted and evaluated at Osaka Minami Medical Center. These patients
included seventeen men and six women who had a mean age of twenty-six years
(range, eighteen to forty-eight years) at the time of evaluation. Eighteen of
the twenty-three patients had a family history of the disease. Preoperative
information was obtained from the medical records and radiographs. All of the
subjects gave informed consent to participate in this study, which was
approved by the institutional review board of Osaka Minami Medical Center.
Surgery
The operations on these patients involved three different types of
procedures: excision of exostoses, corrective procedures, and excision or open
reduction of the dislocated head of the radius. Excision of exostoses was the
primary procedure in all cases. The corrective procedures included lengthening
or corrective osteotomy of the ulna or radius.
The twenty-three patients (thirty-one forearms) underwent a variety of
procedures, either alone or in combination, including (1) excision of
exostoses (thirty-one forearms), (2) lengthening of the ulna (sixteen
forearms), (3) lengthening of the radius (four forearms), (4) corrective
osteotomy of the radius (fourteen forearms), (5) corrective osteotomy of the
ulna (two forearms), (6) open reduction of the dislocated radial head (two
forearms), and (7) excision of the radial head (two forearms). In both
patients who underwent open radial head reduction, we simultaneously performed
an immediate ulnar lengthening, a corrective osteotomy of the radius, and
anular ligament reconstruction with palmaris longus tendon graft.
Seven of the thirty-one forearms underwent more than one operation.
Nineteen of the twenty-three patients underwent surgery before reaching
skeletal maturity; the mean age at the time of the initial procedure was
eleven years (range, three to twenty-three years). The mean follow-up interval
between the final surgical procedure and the time of evaluation was 12.8 years
(range, six to thirty-nine years) (see Appendix).
Surgical Indications
Exostoses were removed if (1) there was interference with joint movement or
if (2) the lesion was prominent, painful, and/or cosmetically undesirable.
The indications for performing corrective procedures were (1) a discrepancy
of >5 mm between the lengths of the ulna and radius with or without bowing,
(2) a radial articular angle of >30°, (3) a carpal slip of >60%, (4)
bowing of the radius, or (5) a combination of these changes. Most patients had
a combination of these changes.
Symptomatic dislocation of the head of the radius was defined as
interfering with joint movement or causing pain.
Clinical Evaluation
An experienced hand surgeon (S.A.) who had not been involved in the
surgical procedures interviewed the patients with use of a questionnaire that
evaluated the outcome with respect to pain, activities of daily living, and
the appearance of the forearm. Pain and restriction of activities were
classified into four categories (none, mild, moderate, or severe), whereas the
appearance of the forearm was classified as satisfactory or unsatisfactory.
The evaluation form can be found in the Appendix. In addition, the ranges of
motion of the wrist, forearm, and elbow were measured, and the grip strength
was also determined.
Radiographic Evaluation
We examined radiographs of both wrists, forearms, and elbows for each
subject. The forearms were classified into three morphological types according
to the system of Masada et
al.11. In type-I
forearms, the main exostosis arises from the distal part of the ulna. The ulna
is relatively short and there is bowing of the radius, but the radial head is
not dislocated. Both tapering of the ulnar head and ulnar tilt of the distal
part of the radius are observed. In type-II forearms, there is ulnar
shortening along with dislocation of the radial head, but bowing of the radius
is less severe than in type-I forearms because of the dislocation. Type-II
forearms are separated into two subgroups. In type-IIa forearms, dislocation
of the radial head is caused by an exostosis arising from the proximal part of
the radius, whereas in type-IIb forearms the dislocation is not due to such an
exostosis. In type-III forearms, the main exostosis arises from the distal
part of the radius and there is a relative shortening of the radius.
Ulnar variance, the radial articular angle, and carpal slip were also
measured. The radial articular angle and carpal slip were measured with use of
the system of Fogel et
al.5. The radial
articular angle was defined as the angle between a line running along the
articular surface of the radius and another line that was perpendicular to a
line joining the center of the radial head to the radial border of the distal
radial epiphysis (the radial styloid in skeletally mature subjects)
(Fig. 1). The normal range of
this angle was 15° to
30°5,11.
Carpal slip was measured by determining the percentage of the lunate that was
in contact with the radius. First, a line was drawn from the center of the
olecranon through the ulnar border of the radial epiphysis (the radial
articular surface in skeletally mature subjects)
(Fig. 2). This line normally
bisects the lunate. An abnormal carpal slip was defined as being present when
ulnar displacement of the lunate exceeded
50%5,11.
Radiographs were also examined for degenerative changes of the joints,
which were defined as narrowing of the joint space and/or the formation of
osteophytes. Deformity of the radial head was considered to be present if
there was evidence of hypertrophy or flattening.
Statistical Analysis
A paired two-group t test was used for comparing data from pairs of groups,
and the Mann-Whitney U test was used for data from unpaired groups. The level
of significance was set at p < 0.05.
Clinical Outcome
Four patients (four upper extremities) complained of mild pain when
performing strenuous activities, whereas the other nineteen patients
(twenty-seven upper extremities) had no pain at the time of follow-up. Five
patients (five forearms) noted mild restriction of daily activities, but the
other eighteen patients (twenty-six forearms) stated that they had no
restrictions. These five patients generally showed limitation of either
pronation or supination, or both, but their daily activities were minimally
affected. Eight patients (eight forearms) stated that the appearance of the
forearm was unsatisfactory, and this unsatisfactory appearance was of greater
importance to these patients than any pain or restriction of activities.
At the time of the final follow-up evaluation, the mean wrist flexion (and
standard deviation) was 59° ± 16°, the mean extension was
66° ± 9°, the mean radial deviation was 14° ±
13°, and the mean ulnar deviation was 43° ± 10°. The mean
forearm pronation was 65° ± 27°, and the mean supination was
73° ± 23°. The mean elbow flexion was 138° ±
11°, and the mean lack of extension was 2° ± 10°. The mean
range of motion at the time of the final follow-up was not significantly
improved compared with the preoperative range, except for a significant
increase of forearm pronation from 43° to 65° (p = 0.004). The average
grip strength was 25.0 kg (Table
I).
Radiographic Outcome
According to the system of Masada et al., twenty-one forearms were
classified as type I, five were classified as type II (with two being
classified as type IIa and three being classified as type IIb), and five were
classified as type III. Preoperative radiographs were available for thirty of
the thirty-one forearms. The average preoperative ulnar variance and radial
articular angle for these thirty forearms were —6.0 mm and 40°,
respectively, whereas the average preoperative carpal slip in twenty-seven
forearms was 53% (the lunate was not ossified in three of the thirty
forearms). At the time of the most recent follow-up of all thirty-one
forearms, the average ulnar variance, radial articular angle, and carpal slip
were —3.5 mm, 41°, and 43%, respectively. When all of the patients
were compared, there was no significant improvement in any of these three
parameters (Table II). These
parameters were not related to the range of motion of the upper extremity, but
each radiographic parameter was related to the cosmetic outcome (p = 0.0129, p
= 0.0003, and p = 0.0155 for ulnar variance, the radial articular angle, and
carpal slip, respectively; Mann-Whitney U test).
Of the thirty-one extremities, two showed degenerative changes of the elbow
joint at the time of follow-up; the changes were osteophytes in both cases.
These two forearms had a type-II deformity, and there was mild restriction of
daily activities due to limited elbow range of motion. No evidence of
degenerative changes was seen at the wrist joint in any of the patients.
With the exclusion of the two limbs that were treated by radial head
resection, there was radial head deformity in ten (34%) of twenty-nine
extremities. Radial head deformity was unrelated to degenerative changes of
the elbow joint and did not influence the range of motion of the upper
extremity.
Outcome of Corrective Procedures
Lengthening and/or corrective osteotomy of the radius or ulna was done
alone or in combination in eighteen forearms. The average preoperative ulnar
variance, radial articular angle, and carpal slip were —8.3 mm, 42°,
and 62%, respectively. In six of these forearms, further progression of
deformity necessitated revision surgery. Almost all of these forearms had
severe deformity, and as many as four corrective operations were percformed.
At one year after the final corrective procedure, the measured parameters
averaged —1.5 mm, 38°, and 40%, respectively, and there was
significant improvement in ulnar variance (p = 0.005) and carpal slip (p =
0.01). Although forearm deformities initially demonstrated improvement, we
found subsequent progression over the long term after the corrective surgery.
At the time of the most recent follow-up, ulnar variance averaged —4.0
mm, the radial articular angle averaged 44°, and carpal slip averaged 44%.
When we assessed the effect of the corrective procedures, radiographic
parameters also demonstrated initial improvement; however, the deformities had
progressed by the time of the most recent follow-up visit, and there was no
significant improvement over the long term.
The only corrective procedure that was associated with complications was
ulnar lengthening. A total of eighteen ulnar lengthening procedures were
performed in sixteen forearms. In eight cases the lengthening was performed
gradually with use of external distraction, whereas in ten cases it was done
immediately with the insertion of a bone graft or the performance of a
step-cut osteotomy. Complications included nonunion in three forearms,
fracture of callus at the site of lengthening in two forearms, and temporary
radial nerve paresis (paresthesia in the radial nerve territory and weakness
of finger extensors) in one forearm. One of the three nonunions occurred after
an immediate ulnar lengthening. The other two nonunions occurred in one
patient who was managed with gradual bilateral ulnar lengthening after
reaching skeletal maturity; this patient also had radial nerve paresis, as
mentioned above. In the three forearms with nonunion, osseous union was
eventually achieved uneventfully by means of bone-grafting and internal
fixation. Fracture of a callus was treated with plaster cast immobilization in
one patient and with intramedullary fixation in the other patient. The patient
with radial nerve dysfunction during distraction of the ulna showed distal
migration of the radius. This migration was easily reduced by dividing the
cord-like portion of the interosseous membrane, and the radial nerve
dysfunction resolved completely.
Outcome of Excision of Exostoses
Excision of exostoses was performed in all of the patients. Ten patients
(eleven forearms) were managed only with excision procedures. The mean age of
these ten patients was 11.2 years (range, five to sixteen years). The location
of the excised exostoses was the distal part of the radius in eight forearms,
the distal part of the ulna in two forearms, and both the distal part of the
radius and the distal part of the ulna in one forearm. Simple excision of
exostoses significantly improved the range of pronation (p = 0.036). With the
numbers available, there were no significant differences between locations
with regard to improvement in forearm rotation. In these eleven forearms, the
preoperative ulnar variance, radial articular angle, and carpal slip averaged
—2.0 mm, 35°, and 37%, respectively. At the time of follow-up, these
three parameters averaged —3.6 mm, 40°, and 42%, respectively, and
there was no significant change in any of the three parameters. There were no
complications of simple excision, and the ten patients who underwent simple
excision procedures had no symptoms at the time of the most recent
follow-up.
Outcome of Radial Head Surgery
Dislocation of the head of the radius (a type-II deformity) was observed in
five extremities. Along with open reduction of the dislocated radial head, we
performed immediate ulnar lengthening, corrective osteotomy of the radius, and
anular ligament reconstruction with palmaris longus tendon graft in two
patients (two forearms) before they reached skeletal maturity, but these
procedures were not effective in either case. Both patients had evidence of
degenerative changes at the elbow joint as well as restricted motion of the
elbow and restricted pronation of the forearm at the time of the most recent
follow-up.
Excision of the dislocated radial head was performed in two patients (two
forearms) after skeletal maturity. Both patients had pain and restricted
motion of the forearm before surgery. In both patients, pain was relieved and
the range of motion of the forearm was improved at the time of the most recent
follow-up.
The present study assessed the long-term results of surgical treatment of
forearm deformities in patients with multiple cartilaginous exostoses in an
attempt to determine the reasonable indications for such surgery. On the basis
of our findings, surgery in these patients is indicated for two purposes: (1)
to improve forearm pronation when it is restricted by an exostosis (with the
most effective procedure being simple excision of the exostosis) and (2) to
improve the appearance of the forearm.
The present study had several weaknesses. It was a retrospective case
review without any controls (nonoperatively treated extremities), only
twenty-three of thirty-four patients were available for the final follow-up
evaluation, and some preoperative data (grip strength) were unavailable.
Furthermore, a variety of operative procedures were performed (often in
combination), making it difficult to draw definite conclusions. However,
little information has been published on the functional outcome for patients
with multiple cartilaginous exostoses who have undergone corrective forearm
surgery, and, to our knowledge, there have been no previous reports about the
long-term results of surgical treatment of forearm deformities. Therefore, our
data may be useful for selecting among treatment options.
A number of techniques for the surgical treatment of forearm deformities
have been
described5,7,9,11-15,
but the operative treatment of such deformities in patients with multiple
cartilaginous exostoses remains
controversial14,15.
Fogel et al. concluded that deformities of the forearm should be treated early
and aggressively to prevent disability by employing procedures such as
excision of exostoses and ulnar lengthening with or without radial
hemiepiphyseal stapling or
osteotomy5. Peterson
reported that forearm deformities were the most frequent cause of functional
impairment in patients with multiple exostoses and advocated aggressive
management as soon as it became clear that the growth of the affected bones
was being altered, stating that prevention of progressive deformity and
functional impairment were the paramount
goals6. However,
Stanton and Hansen evaluated the radiographic anatomy, functional outcome, and
impairment ratings of twenty-eight patients with hereditary multiple exostoses
and concluded that reasonable function was preserved despite the occurrence of
deformity16. Arms
et al. performed a telephone questionnaire evaluation of thirty-seven patients
who had forearm deformities and found that most patients maintained adequate
function after reaching skeletal maturity despite having severe
deformity17.
Likewise, we found that there was little restriction of daily activities in
patients with a residual forearm deformity postoperatively and that
radiographic parameters were not related to the final range of motion of the
upper extremity.
Noonan et al. assessed the functional outcome for the forearm in a study of
thirty-nine adults (seventy-seven forearms) with a mean age of forty-two years
who had multiple hereditary osteochondromatosis and had not undergone
corrective
surgery14. Although
we cannot fully compare those results with the postoperative functional
results in our series, a review of their results for untreated patients
suggests that corrective surgery did not achieve any marked improvement in
function. They also reported that the appearance of the forearm was not
related to the functional outcome. Likewise, our findings indicate that most
forearm deformities do not influence the functional outcome. However, we found
that postoperative radiographic parameters were related to complaints about
the appearance of the upper extremity. Noonan et al. reported that seventeen
(44%) of thirty-nine patients found the arms to be cosmetically unappealing
because of shortening, angulation, or
bumps14. Wood et
al., in a report on ten patients who had undergone various operations
(including corrective procedures such as forearm bone lengthening and/or
osteotomy), concluded that, although function only showed minimal improvement,
the appearance of the limbs was markedly
improved9.
Pritchett, in a report on the results of ulnar lengthening in eight patients
(ten forearms), concluded that there was improvement in the appearance,
forearm movement, and radial head
stability7.
Therefore, when the patient finds the appearance of the forearm to be
problematic, corrective surgery may be a reasonable option. However, Pritchett
also reported that partial recurrence of forearm deformities occurred in
skeletally immature
patients7, and we
similarly found that deformity sometimes progressed after corrective surgery.
The reported complication rate for lengthening of the forearm has varied
widely, from 0% to
100%5,7,11,18.
In the present series, complications occurred in association with five (28%)
of eighteen ulnar lengthening procedures, suggesting that this operation
should be performed with great caution.
Previously, we believed that forearm deformities were the most frequent
cause of functional impairment, and we recommended corrective procedures to
prevent progressive deformity and functional impairment. Our surgical
indications included a discrepancy of >5 mm between the lengths of the ulna
and radius with or without bowing, a radial articular angle of >30°, a
carpal slip of >60%, bowing of the radius, or a combination of these
changes. However, we now think that forearm deformities are unrelated to
function and we no longer recommend corrective procedures for the prevention
of functional impairment.
Fogel et al. reported that the excision of exostoses could not correct
deformities but might arrest or retard their
progression5. Shin
et al. reported that the simple excision of exostoses did not improve the
radiographic parameters but led to a significant increase in supination of the
forearm (p =
0.049)19. We also
found that excision of exostoses alone did not correct forearm deformities,
but simple excision achieved significant improvement of forearm pronation and
might also retard the progression of deformities.
Stanton and Hansen reported that the status of the radial head was not
associated with either the subjective assessment score or with the level of
performance in the hand test of
Jebsen16. In
addition, Dahl stated that he did not perform direct reduction of a
chronically dislocated radial head because stiffness and pain could
occur20. In the
present series, dislocation of the radial head was treated with open reduction
(two forearms), excision (two forearms), and observation (one forearm). Radial
head reduction was not effective in either patient, with degenerative changes
of the elbow joint and restricted movement of both the elbow and forearm
(causing slight limitation of daily activities) being evident at the time of
the most recent follow-up. Excision of the dislocated radial head and
observation were both associated with a better outcome as there was no
degeneration of the elbow joint and a good range of motion of the upper
extremity was maintained. However, because the numbers were small in this
series, it is difficult to draw firm conclusions.
In summary, we believe that simple exostosis excision is reasonable when
there is restriction of forearm pronation. When the primary concern is
appearance, a corrective procedure is an option; however, it should be viewed
with caution as there can be recurrence of deformity, especially in immature
patients, and nonunion may occur following ulnar lengthening. As an
alternative, simple exostosis excision may retard the progression of forearm
deformity.
Tables showing the details on all study subjects and the questionnaire used
in this study are available with the electronic versions of this article, on
our web site at jbjs.org (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). ?
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