abnormality. Our results suggest that subclinical nerve damage is a very frequent complication of tibial lengthening. Surgical lengthening of the tibia and femur.
PERIPHERAL
NERVE
DAMAGE
DURING
LIMB
LENGTHENING NEUROPHYSIOLOGY
IN
G. GALARDI,
FIVE
CASES
G. COMI,
OF
L. LOZZA,
San
RaJJ#{224}ele Hospital,
TIBIAL
P. MARCHETTINI,
R. FACCHINI,
From
BILATERAL
LENGTHENING
M. NOVARINA,
A. PARONZINI
Milan
and
San
Gerardo
Hospital,
Monza
Limb lengthening is used to correct leg length discrepancy and to increase stature. The reported frequency of peripheral nerve complications varies from 5% to 30%, but is probably underestimated. Damage may be direct or be caused by overstretching of the nerves. We have used electrophysiological tests to evaluate five patients during bilateral tibial lengthening by the Ilizarov method. Results after 24 to 107 days oflengthening showed electromyographic evidence of partial muscle denervation in all 10 limbs, with reduced motor conduction velocities in two tibial nerves and three common peroneal nerves. The sensory conduction velocity in the sural nerve was always unchanged. A clear relationship was shown between the amount of tibial lengthening and the degree of electrophysiological abnormality. Our results suggest that subclinical nerve damage is a very frequent complication of tibial lengthening. Surgical
lengthening
of the
tibia
and
femur
was
intro-
patients having tibia! lengthening. Pouliquen et a! (1984) reported clinical neuropathy in 17 of 108 patients, and suggested that nerve and vessel complications should be investigated by more sophisticated methods.
duced early in the twentieth century. Codivilla (1905) was the first to apply traction after an osteotomy, obtaining 3 to 8 cm of limb elongation, and both Putti (1918) and Abbott (1927) described the use of progressive distraction. common
Limb lengthening in the l950s after
distraction
devices
More
(Anderson
1972;
De
various
Bastiani
devices (Ilizarov et a! 1986). Despite
some
and
the
tissues,
are still vessels,
incidence
remarkably
of
hypo-aesthesia
had lengthening myelitis, and neuropathy
of the Kawamura in 27%
L. Lozza,
MD,
P. Marchettini, M. Novarina, Ospedale San
should
© 1989 British 0301-620X/90/l
JBoneJoint
VOL.
72-B,
(Car!iotz
et a! 1980, De Bastiani the
limb
sequelae reported
exclusively
incidence
of limb
no nerve
lengthening complications
et al 1986).
of neuropathy
We aimed
caused
by
to
lower
lengthening.
made
a prospective
disproportionate ening on 10 limbs
AND
METHODS
study
dwarfism, during (Fig. 1). We used
of
five
patients
bilateral the surgical
with
leg lengthtechnique
is
observed who had of poliosigns of
poliomye!itic
of Neurophysiology
Neurophysiologist
MD, Orthopaedic MD, Orthopaedic Hospital, Monza,
Correspondence
reported
Shih (1977) in almost all patients
series had
quantify
We
involve
some
to have
PATIENTS
lengthened
complications
MD, Neurophysiologist MD, Orthopaedic Surgeon Raffaele, Via Olgettina 60,
R. Facchini, A. Paronzini, San Gerardo
may
of the
and
of almost
new
hand,
reported
materials,
which
tibia for the et a! (1968)
G. Galardi, MD, Neurophysiologist G. Comi, MD, Associate Professor
developed
been
1971 ; Wagner more accurate
sophisticated nerves
nerve Hang
have
reported
and
variable.
temporary
surgeons
use of more
complications
the soft limb. The
On the other have
became more of fixation-
1967).
recently,
fixation-distraction
techniques
techniques the introduction
Editorial
be sent
No. 1, JANUARY
Milan,
Italy.
to Dr G. Galardi.
Society
179 $2.00 Surg[Br] 1990;
201 32 Segrate,
Surgeon Surgeon Milan, Italy.
72-B:
1990
ofBone 121-4.
and Joint
Fig.
Surgery Bilateral tibial and radiographic
lengthening appearances
in a young during
I achondroplastic lengthening.
dwarf.
Clinical
21
G. GALARDI,
122
of I!izarov circumferential
G. COMI,
(197 1 ). This involves rings, with crossed
transfixing metaphyses.
bone at the level ‘Compactotomy’
incomplete
cortical
cavity
its
and
through midshaft
L. LOZZA,
of is
resection,
blood
application
wires,
proximal and then performed
the
untouched.
a 2 cm anterior skin and the fracture
of
Kirschner
leaving
supply
twisting the circumferential third ofthe fibula is excised.
the
P. MARCHETfINI.
distal by
medullary
This
is done
incision over the proximal completed posteriorly by rings. A section of the distal The lower and upper fixation
M. NOVARINA,
Table
intervals during the lengthening. investigations were performed
after
completion
limbs)
were
Neurophysiological lengthening
52 to 107 days later.
also
assessed
halfway
Three through
(six
(MAP)
for
tibia! nerves, with amplitude ofsensory
Table
II.
the
deep
peronea!
results
1
Time (days) 0
Length increase
(j,ercent)
lengthenings
Length Case
Age (yr)
Dia
I
13
Rickets
2
20
3
3
4 5
Final
I 2
288 288
378 378
31.2
Dyschondroplasia
3 4
215 215
270 270
25.5 25.5
Dyschondroplasia
5 6
129 129
170 170
31.7 31.7
19
Achondroplasia
7 8
160 160
215 212
34.3
24
Dyschondroplasia
9 10
280 280
310 320
10.7 14.2
per oneal
nerve
Posterior
tibia!
nerve
(mV)
Velocity (m/sec)
Distal latency (msec)
-
-
-
-
2.8 2.8
5.0 3.0
60.0 49.!
3.2 3.4
Motor velocity (rn/see)
Distal latency (msec)
-
59.0 55.9
MAP Amplitude
Sural
Amplitude (mY)
SAP amplitude
-
-
-
56.4 52.4
22 12
-
-
55.5 53.0
22 14
-
-
107 0 24 107
0 5.0 31.2
-
-
-
-
-
49.3 41.6
3.2 2.8
4.0 2.0
54.! 46.9
4.6 4.8
13 13
0 107
0 25.5
-
-
-
-
46.8
3.6
4
0 107
0 25.5
-
-
44.3
3.4
5
0 52
0 31.7
48.2 36.6
2.4 3.2
6
0 52
0
51.9 39.2
2.3 2.8
51.6 47.2 46.3
2.8 2.9 2.9
51.6 47.9 45.0
2.8 2.7 3.2
59.7 49.5 46.5 58.3 47.7 45.8
2
3
7
8
9
10
Normal values
0 14 65 0 14 65 0 30 53 0 30 53
31.7 0
11.2 34.3 0
4.0 32.5 0
5.3 10.7 0
8.9 14.2
>43.6
31.2
32.5
nerve
Sensory velocity (mince)
0 5.0 31.2
24
Increase (percent)
Initial
Limb
posterior
velocity and for the sura!
in mm
in 10 limbs
Deep
Limb
and
sensory nerve conduction action potentials (SAP)
Electrophysiological
of 10 tibia!
lengthening.
The investigations included motor nerve conduction velocity, distal latency and the amplitude ofmotor action potentials
I. Details
and
patients
A. PARONZINI
nerve. Needle electromyography of tibialis anterior and the medial gastrocnemius was also performed. The results were compared with the normal values currently accepted by our neurophysiology laboratory (Table II). A muscle was considered to be denervated only where spontaneous activity was seen, since mere reduction of spatial recruitment may result from reduced voluntary activity caused by the presence of the fixationdistraction apparatus. The lengthening achieved was recorded at every electrophysiological examination ; this varied from 4% to 34.3% of the initial length.
rings are then linked by threaded bars and nuts, which allow of controlled distraction. This is applied four times a day at regular intervals to give an average daily lengthening of 1 mm. The patient’s age, clinical diagnosis, initial tibial length, and total lengthening were recorded (Tab!e I). All five patients had detailed neurological examinations at before
R. FACCHINI,
15 13 -
(mY)
-
-
46.8
4.8
-
-
12.0
44.2
4.8
12
44.1
14
5.0 0.2
49.1 44.0
2.2 2.2
27 26
46.4
40
-
-
5.0 0.2
47.4 40.6
2.3 2.4
25 20
45.8
45
-
-
8.0 3.0 2.5
47.5 47.3 40.7
3.8 3.5 3.9
25 25 8
53.1
40
-
-
-
-
8.0 6.0 1.5
47.6
2.8
30
56.6
40
-
-
-
-
-
43.1
3.4
19
-
-
3.3 3.5 4.3
10.0 1.0 1.0
58.3 57.3 55.5
3.8 4.4 4.6
25 13 11
59.0
40
-
-
-
-
3.4 3.8 3.5
12.0 5.0 5.0
57.6 56.0 51.1
3.7 3.9 4.6
23 12 10
59.0 60.7 50.6
40 14 17
5.0
>43.0
THE
-
15
JOURNAL
10
45.8
>45.2
OF BONE
-
>7
AND
JOINT
SURGERY
PERIPHERAL Table
HI.
Electromyographic
NERVE
DAMAGE
results
in 10 tibial
Tibialis Length increase
Time (days)
(percent)
0 24 107 0
DURING
LIMB
lengthenings
anterior
Medial
Recr
Spontaneous activlty*
MUPt
Recr
0 5.0 31.2
+ +
Reg Poly
Average Average
+ +
Reg Poly
Poor Poor
24 107
0 5.0 31.2
+ +
Reg Poly
Average Average
+ +
Reg Poly
Poor Poor
3
0 107
0 25.5
+
Poly
Average
+
Poly
Poor
4
0 107
0 25.5
+
Poly
Average
+
Poly
Poor
5
0 52
0 31.7
+
Poly
Average
-
Reg
Poor
0
0 31.7
+
Poly
Average
-
Reg
Poor
Reg Poly
Average Average
Reg Poly
Poor Poor
2
6
52 7
0 11.2
0
14 65 8
30 53
0 30 53
*
t
presence
+
-
4.0
+
Reg Poly
Average Average
+
Reg Poly
Poor Poor
0 5.3 10.7
+ +
Reg Poly
Average Average
+ +
Reg Poly
Poor Poor
0 8.9 14.2
+ +
Reg Poly
Average Average
+ +
Reg Poly
Poor Poor
of fibrillation
potentials
and
slow
positive
Reg, regular; Poly, polyphasic recruitment at maximum effort
RESULTS
(>
12%)
and
Before osteotomy, all five patients had normal nerve conduction parameters. After osteotomy and during distraction, two patients reported paraesthesia in the distribution of the superficial peroneal nerve ; this was bilateral in one. No patient had any significant paresis of limb muscles, but accurate testing was made difficult because the fixation-distraction apparatus caused some pain during tests of strength against resistance. The neurophysio!ogical tests showed some nerve abnormalities in a!! the operated limbs ; these are reported to time
intervals
from
osteotomy and the amount of lengthening. Conduction in the deep peroneal nerve showed a reduction of the amplitude of MAP in eight of the 10 limbs; these were pathologically low for motor nerve conduction in three Where
repeated
tests
were
made,
there
were
almost always signs of a gradual reduction of motor conduction velocity during the lengthening. Motor conduction in the tibial nerve showed pathologically reduced velocities in two limbs, and in addition, a gradual reduction in motor conduction velocity in six of eight limbs during lengthening. Needle electromyography showed partial denervation in the motor distribution of the deep peroneal nerve in a!! cases, VOL. 72-B,
No. 1, JANUARY
1990
-
waves
in that
limbs.
in relation
+
0
motor unit potentials: temporal and spatial
III
-
32.5
0
10
-
34.3
0 14 65
9
limbs.
gastroenemius
MUPt
I
II and
123
Spontaneous activity5
Limb
in Tables
LENGTHENING
normal
of the posterior
Sensory
conduction
tibia! in the
nerve
in eight
of the
nerve
remained
sural
10
throughout.
DISCUSSION Neurophysiological during and after series,
one
or
abnormalities limb-lengthening more
being
found
of peripheral were common in
all
patients.
nerves in our The
longitudinal observations showed that motor nerve conduction velocity tends to reduce gradually as lengthening proceeds. Reduction of nerve conductivity may be partly due toloss offibres with a high conduction velocity, since
the
axonal
damage
relates
to
the
leg
muscle
fibrillation potentials, and may be partly caused by damage to the myelin sheaths. Only moderate denervation of leg muscles was found ; this explains the absence of apparent weakness on clinical examination. The frequency of nerve injury may be due to the fact that our patients were all treated for dwarfism in whom there is likely to be more traction on the nerves than in patients with acquired limb discrepancies. Nerve damage may occur at two stages : during the twisting movement used to complete the cortical fracture and from traction caused by gradual lengthening. Opinions concerning pathogenesis are varied. Wagner
0. GALARDI,
124
(1972)
attributes
nerve
G. COMI,
damage
L. LOZZA,
to
P. MARCHETFINI,
compression
ment which avoided.
to permit
is required
the
early
detection
if serious
clinical
of nerve
damage
R. FACCHINI,
involve-
is to be
A. PARONZINI
REFERENCES
from
excessive fascial tension ; he suggests decompression by fasciotomy. Gibson et a! (1986) report that weakness of foot dorsiflexion may be a complication ofthe osteotomy, but evidence supporting traction as the cause is supplied by Kawamura et a! (1968) who showed experimentally that nerve damage depends on the range and rate of lengthening. In our patients the greatest damage was suffered by the peroneal nerve, and this may be due to its close relationship with the head of the fibula. In some of our cases, denervation potentials were seen as early as 24 days after the start of lengthening. Since fibrillation can occur some 10 to 20 days after damage to motor nerve fibres, these early signs are likely to result from nerve injury at the original operation. On the other hand, the gradual reduction of conductivity during lengthening suggests that traction has an important role. We believe that neurophysiological monitoring of nerve function in limbs subjected to lengthening is indicated
M. NOVARINA,
AbbOtt
LC. Joint
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