Deformities of the elbow in achondroplasia

Deformities of the elbow in achondroplasia
Hiroshi Kitoh, Takahiko Kitakoji, Kazuhiro Kurita, Mitsuyasu Katoh,
Yuji Takamine
From Nagoya University, Aichi, Japan
Lack of full extension of the elbow is a common
depressed nasal bridge, bowing of the lower limbs, and an
abnormality in patients with achondroplasia. We
increased lumbar lordosis. It is caused by mutations in the
studied 23 patients (41 elbows) clinically and
gene which encodes the fibroblast growth factor receptor 3
2-4
radiologically. Extension of the elbow was assessed
(FGFR3)
and is transmitted as a fully penetrant autoso-
clinically and the angle of posterior bowing of the
mal dominant trait. Most cases are sporadic. The clinical
distal humerus was measured from lateral
features and surgical implications of deformities of the
5
radiographs.
spine and lower limbs have been well described. By
There was limited extension of the elbow in 28
contrast, deformities of the upper limb have not been fully
(68.3%) and the mean loss of extension was 13.1°.
investigated. These include characteristic shortness of the
Posterior bowing of the humerus was seen in all
humerus, trident hands, and variation in the length of the
elbows with a mean angle of 17.0°. There was a
fingers. Lack of full extension of the elbow seems to be the
positive correlation between these two measurements.
earliest clinical manifestation and one of the most common
Posterior bowing greater than 20° caused a loss of full
abnormalities of the upper limb.
elbow extension. Posterior dislocation of the radial
A flexion deformity of the distal humerus is commonly
head was seen in nine elbows (22.0%). The mean loss
seen on radiographs of patients with achondroplasia and
of extension of the elbows was 28.7° which was
other short-limbed skeletal dysplasias which are associated
significantly greater than that of these elbows in which
with loss of extension of the elbow. Subluxation or disloca-
the head was not dislocated (8.7°), although posterior
tion of the abnormally-shaped head of the radius is also
bowing was not significantly different between these
seen in some patients (Fig. 1). These bony abnormalities
two groups (19.3° and 16.3°).
may be related to loss of extension, but to what extent has
Posterior bowing of the distal humerus is a
not been investigated. We have attempted to evaluate the
principal cause of loss of extension of the elbow.
prevalence of limited elbow extension and associated radio-
Posterior dislocation of the radial head causes further
logical abnormalities in patients with achondroplasia.
limitation of movement in the more severely affected
joints.
Patients and Methods
J Bone Joint Surg [Br] 2002;84-B:680-3.
Received 18 December 2001; Accepted 31 January 2002
We studied 23 patients, 11 males and 12 females with a
mean age of 11 years 8 months (1 year 7 months to 39
years 11 months). We excluded patients with other short-
Achondroplasia is one of the most common forms of
limbed skeletal dysplasias associated with extension
osteochondrodysplasia with an incidence of 1 in 26 000
deformity such as pseudoachondroplasia or hypochondro-
1
live births. It is characterised by rhizomelic, short-limbed
plasia. Both elbows were assessed clinically and radi-
dwarfism, relative macrocephaly, frontal bossing, a
ologically. Five were excluded because adequate
radiographs could not be obtained, leaving 41 elbows in the
study. Extension was estimated clinically with the elbow
maximally extended. Lateral radiographs were taken with
H. Kitoh, MD, Orthopaedic Surgeon
the elbow flexed to about 90°. The flexion deformity of the
T. Kitakoji, MD, Assistant Professor
K. Kurita, MD, Orthopaedic Surgeon
distal humerus was estimated by measuring the posterior
M. Katoh, MD, Orthopaedic Surgeon
bowing angle. This was defined as the angle formed by
Y. Takamine, MD, Orthopaedic Surgeon
Department of Orthopaedic Surgery, Nagoya University School of Medi-
lines drawn parallel to the mid-diaphyseal and distal dia-
cine, 65 Tsurumai-Cho, Showa-ku, Nagoya, Aichi 466-8550, Japan.
physeal axes (Fig. 2). Dislocation of the head of the radius
Correspondence should be sent to Dr H. Kitoh.
was also assessed on the lateral radiographs. All measure-
©2002 British Editorial Society of Bone and Joint Surgery
ments were made by the same investigator (HK).
0301-620X/02/513107 $2.00
Statistical analysis. Spearman’s rank correlation test was
680
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DEFORMITIES OF THE ELBOW IN ACHONDROPLASIA
681
Fig. 1
Fig. 2
Lateral radiograph of the elbow of an eight-year-old girl with
Radiograph showing that the angle of posterior bowing of
achondroplasia. Posterior bowing of the distal humerus and poster-
the distal humerus is determined by lines drawn parallel to
ior dislocation of the head of the radius are seen.
the mid-diaphyseal and distal diaphyseal axes.
30
°
)
°
)
30
25
25
20
20
15
15
10
10
r=0.639
r=0.691
5
p<0.0001
5
p<0.0001
Angle of posterior bowing (
0
Angle of posterior bowing (
0
0
5
10
15
20
25
30
35
0
5
10
15
20
25
30
35
Loss of extension (°)
Loss of extension (°)
Fig. 3a
Fig. 3b
Graphs showing Spearman’s rank correlation with a significant correlation between loss of extension and the angle of posterior bowing
(R = 0.639; p < 0.0001) (a) and a better correlation between loss of extension and the angle of posterior bowing (R = 0.691; p < 0.0001)
in elbows without dislocation of the head of the radius (b).
used to determine the relationship between loss of exten-
with a mean value of 17.0° (10 to 28) was seen in all
sion and the posterior bowing angle. The mean values were
elbows. There was a positive correlation between loss of
analysed using the unpaired t-test between the groups with
extension and posterior bowing (r = 0.639; Fig. 3a). All
and without dislocation of the head of the radius. All
elbows with bowing of more than 20° failed to extend
analyses were performed using Statview 4.5 (Abacus Con-
fully.
cept, Berkeley, California).
Posterior dislocation of the head of the radius was seen
in nine elbows (22.0%). All had loss of full extension with
Results
a mean deficit of 28.7° (15 to 34) which was greater than
the mean angle of posterior bowing of 19.3° (14 to 28). In
Loss of extension was present in 28 elbows (68.3%) and
those without dislocation, the mean loss of extension was
had a mean value of 13.1° (0 to 34). The mean age of these
8.7° (0 to 29) which was significantly smaller than the
patients was 12.7 years which was higher than that of those
mean posterior bowing of 16.3° (10 to 26), but where
without a deficit of extension (10.8 years). This was not
dislocation was present loss of extension was significantly
statistically significant. Posterior bowing of the humerus
greater (p < 0.01), although posterior bowing was not nota-
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682
H. KITOH, T. KITAKOJI, K. KURITA, M. KATOH, Y. TAKAMINE
Fig. 4a
Fig. 4b
Fluoroscopic examination of the elbow of a 13-year-old patient with achondroplasia and dislocation of the head of the
radius showing a) marked posterior displacement of the radial head in the fully flexed position and b) impingement of the
radial head in full extension.
Fig. 5a
Fig. 5b
Anteroposterior a) and lateral b) radiographs of the elbow of a 20-year-old woman with
achondroplasia showing hypoplasia of the capitellum and posterior dislocation of the radial
head.
bly different. Unilateral dislocation of the head of the
ded until it appeared to impinge and block extension (Fig.
radius was seen in two patients and extension of the elbow
4b).
in both was more limited on the affected side although
posterior bowing was not markedly different. There was a
Discussion
different correlation between loss of extension of the elbow
and the angle of posterior bowing in patients in whom the
Deformities of the elbow are particularly significant
head of the radius was not dislocated (r = 0.691) (Fig.
diagnostically in young children with achondroplasia.
6
3b).
Bailey reviewed the clinical and radiological findings in
Elbows in which the head of the radius was dislocated
41 patients and described various deformities of the
were also examined using fluoroscopy in both the flexed
upper limb including loss of extension, limited supination
and extended positions in order to establish how the range
or pronation, a prominent radial head, a short ulna, and
of elbow movement was influenced. The head showed a
cubitus varus. A deficit in extension was the most com-
prominent posterior dislocation in the flexed position (Fig.
mon, being present in 38 of the 41 patients (92.7%). Only
4a) and was transferred anteriorly as the elbow was exten-
three patients had full extension. Bailey also observed
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DEFORMITIES OF THE ELBOW IN ACHONDROPLASIA
683
that loss of extension increased with age. The number of
in infants with achondroplasia. The significantly smaller
elbows with this deformity in our series was lower
defect in extension in the presence of posterior bowing in
(68.3%) and is probably a reflection of the relative youth
those patients without dislocation suggests that the soft-
of our patients. Even the 13 elbows without an extension
tissue structures around the elbow may be lax, as is seen in
deficit may represent a mild deformity since most normal
other joints in achondroplasia. In younger patients these lax
adolescents and infants have some hyperextension of the
soft tissues are likely to compensate for the curved humerus
joint.
in elbow extension. Conversely, the higher rate of elbows
Posterior bowing of the distal humerus was a consistent
with limited extension in older patients may be due to
radiological abnormality and when greater than 20° resul-
relatively tight soft tissues.
ted in loss of extension. Restriction of elbow extension,
No benefits in any form have been received or will be received from a
even when shoulder function is normal, may cause func-
commercial party related directly or indirectly to the subject of this
article.
tional impairment of a shortened arm. Recently, surgical
lengthening of the humerus has been performed to improve
the function of the arm and the activities of daily living in
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