Assessment of a skeletally imma-ture patient with a limb-length dis-crepancy and formulation of a treat-ment plan require an understanding of the etiology of the disorder and the natural
Trang 1Assessment of a skeletally
imma-ture patient with a limb-length
dis-crepancy and formulation of a
treat-ment plan require an understanding
of the etiology of the disorder and
the natural history of the condition,
as well as the ability to predict the
ultimate discrepancy at maturity
The purpose of this article is to
pro-vide a systematic approach to the
patient with limb-length inequality
and to discuss the potential pitfalls
of assessment and the options for
treatment
Mechanisms of
Compensation
Limb-length inequality is common
in the general population.1 A
vari-ety of mechanisms are used to
compensate for the resultant gait
asymmetry.2-4 Adults tend to walk
in a plantigrade fashion, ÒvaultingÓ
over the long leg Children may use either this mechanism or toe walking on the short side, which levels the pelvis and decreases the effective trunk sway during gait
Despite the prevalent belief that limb-length discrepancy may be deleterious to the spine or the hip, there is little evidence to support this assumption While increased trunk shift, vaulting, and toe-walking all increase the energy expenditure involved in walking, these mecha-nisms appear to have little effect on otherwise-healthy individuals The data relating to the possibility that limb-length discrepancy causes low back pain in adults are contradic-tory.5,6 Back pain is usually not a complaint in children with limb-length discrepancy The effect of limb-length inequality on spinal alignment and the hip can be noted only when the individual is bearing weight equally on both legs The
effort to produce an erect trunk results in functional scoliosis.7 According to the literature,
howev-er, the convexity of the curve is vari-able.8 The center-edge angle of the hip of the long leg will be decreased due to the compensatory pelvic obliquity The long-term effects of these functional changes are undoc-umented and largely speculative In the course of normal daily activity, most people spend little time stand-ing on both legs with their weight evenly distributed
The significance of limb-length differences remains controversial
In general, individuals with con-genital or acquired inequalities that have developed over the course of many years accommodate more readily than those with acute ac-quired differences due, for exam-ple, to trauma.2,3 The literature suggests that individuals with limb-length disparities less than 2.0
to 2.5 cm usually require no active intervention or, at most, a shoe lift.1
Dr Stanitski is Professor, Department of Orthopaedic Surgery, Medical University of South Carolina, Charleston.
Reprint requests: Dr Stanitski, Department of Orthopaedic Surgery, Medical University of South Carolina, Suite 708, 96 Jonathan Lucas Street, Charleston, SC 29425.
Copyright 1999 by the American Academy of Orthopaedic Surgeons.
Abstract
Assessment and treatment of limb-length inequality, particularly in the
grow-ing child, is a challenggrow-ing task Evaluation of the discrepancy requires an
understanding of the significance of the disparity, as well as the natural history
of the disorder, before formulation of a treatment plan In the immature patient,
consistent longitudinal data are essential to avoid pitfalls in the projection of
ultimate length difference Therapeutic options range from no treatment or use
of a simple shoe lift to a surgical shortening or lengthening procedure The
cur-rent indication for lengthening is a disparity exceeding 5 to 6 cm
Epiphys-iodesis or femoral shortening is useful for smaller discrepancies or for residual
differences following a contralateral lengthening Lengthening is done with a
circular or cantilever external fixator, which may be combined with an
intramedullary rod.
J Am Acad Orthop Surg 1999;7:143-153
Assessment and Treatment Options
Deborah F Stanitski, MD
Trang 2Clinical Assessment
The causes of limb-length inequality
are summarized in Table 1 While
not exhaustive, this list includes the
most commonly seen entities
The patientÕs history will most
often elucidate the etiology of the
limb-length discrepancy, whether
congenital or acquired The family
history may be helpful in identifying
inherited disorders, such as
neurofi-bromatosis and multiple hereditary
exostoses The birth history and time
of onset may be important
Dis-crepancies noted at birth are most
commonly due to the congenital
hypoplasia syndromes
Hemihyper-trophy, Klippel-Trenaunay-Weber
syndrome, Proteus syndrome, and
neurofibromatosis are frequently
noted in the perinatal period The
occurrence of generalized sepsis, a
septic joint, or osteomyelitis can be a
contributing factor Other common
causes of acquired deformities are
trauma, inflammatory disorders, and
neurologic injury
Skin examination may reveal
vascular or pigmentation
abnor-malities or scarring Abnorabnor-malities
overlying the spine, such as a
dim-ple, sinus, or hairy patch, should
prompt investigation of the
under-lying spine and spinal cord
Ex-amination of the limbs should
re-veal differences in size and muscle
strength In hemihypertrophy and
hemangiomatous conditions,
ab-normalities may be confined to the
lower extremity or may involve the
entire side of the body
With the patient supine, the
lower extremities should be fully
extended with the pelvis level to
best assess the relative amount of
shortening Tape measurement is
generally useless due to the
im-precision of finding reproducible
landmarks, particularly at the
anterior superior iliac spine.5 If
no difference in the limbs can be
appreciated clinically by noting
the relative relationship of the
medial malleoli, the difference is usually small and may be insignif-icant The Galeazzi test should be performed by flexing the hips 90 degrees and noting relative knee height (Fig 1) This will elucidate whether limb-segment involve-ment is femoral or tibial
The patient with limb-length inequality should then be examined while standing with blocks placed under the short leg to level the pelvis This gives the examiner a reasonably accurate clinical mea-surement of limb-length inequality, including the potential contribution
of the foot height Palpation of the iliac wings and observation of the two posterior dimples overlying the sacrum can also be helpful With the pelvis level, the spine is exam-ined for evidence of frontal- or sagittal-plane deformity Coexistent spinal deformity can be identified
by examining the spine with the patient seated, which eliminates any potential contribution of limb-length difference The contribution
of foot height to limb-length dis-crepancy is assessed clinically by measuring the distance from the floor to the medial malleolus with the patient standing This is espe-cially helpful in virtually all con-genital conditions distal to the knee
in which foot height is reduced on the affected side Examples of this are the fibular hypoplasia syn-dromes and congenital posterome-dial bowing of the tibia
Motor and sensory examinations should be performed to rule out any neuromuscular abnormalities
Joint range of motion and stability should be assessed clinically and abnormalities, such as contractures, noted A flexion contracture of the knee or hip will produce a func-tional limb-length inequality Hip adduction or abduction contrac-tures will also produce a functional limb-length inequality
The patientÕs gait should be examined while walking
bare-foot and also with any shoes, lifts, or orthoses Observation of rapid walking or running is use-ful to magnify mild gait asym-metries
Table 1 Causes of Limb-Length Discrepancy
Congenital causes Limb hypoplasia syndromes Proximal
Proximal femoral focal deficiency
Congenital short femur Hypoplastic femur Distal
Fibular hemimelia Tibial hemimelia Congenital posteromedial bowing
Hemihypertrophy or atrophy Idiopathic
Klippel-Trenaunay-Weber syndrome
Proteus syndrome Skeletal dysplasias Ollier disease Fibrous dysplasia Multiple hereditary exostoses Neurofibromatosis
Chondrodysplasia punctata Acquired causes
Trauma Acute bone loss Physeal fracture Burns
Irradiation Iatrogenic Infection Osteomyelitis Septic arthritis Purpura fulminans Inflammation Juvenile rheumatoid arthritis Hemophilia
Pigmented villonodular synovitis
Neurologic Closed head injury Polio
Spinal cord injury or tumor Peripheral nerve injury Myelomeningocele Cerebral palsy
Trang 3Radiologic Assessment
A variety of radiologic techniques
are available for the assessment of
limb-length discrepancy Past
stan-dards have been scanography,
orthoradiography, and
teleradiogra-phy The teleradiograph is a single
exposure on a long 14×36- or 14×54-in
film, taken from a 6-ft distance with
the patient standing with a ruler
placed (ideally) in the center of the
cassette It has the advantage of
demonstrating axial deformity but
is subject to magnification error In
the authorÕs experience, this
aver-ages 6% and can be easily calculated
by using a magnification marker of
known size on the film Another
advantage of this technique is the
demonstration of frontal-plane
deformity as well as limb-length
discrepancy on one film
Ortho-radiography avoids magnification
by using separate exposures of the
hip, knee, and ankle.9 Scanography
follows the same technique as
orthoradiography, but the film size
is reduced by moving the cassette beneath the patient between expo-sures The difficulty with the latter two techniques is that patient move-ment between exposures produces measurement error All three tech-niques are inaccurate if there is a fixed hip- or knee-flexion contrac-ture
In the past decade, computed tomographic (CT) scanogram tech-niques have been reported by a number of centers The images ob-tained entail considerably less radi-ation exposure than conventional radiographs,10,11 but they have not been shown to be more accurate, except in patients with a significant knee-flexion contracture.10 De-pending on the institutional avail-ability of CT, the study may need to
be scheduled for a second visit
The CT study is more expensive than a standard radiographic exam-ination (e.g., approximately $620 in our institution for technical and interpretation fees, compared with
$120 for a teleradiographic study)
Ultrasound has been utilized as a tool for assessment of limb lengths Although it has the benefit of being performed without the use of ioniz-ing radiation, it is less accurate than standard radiologic techniques and may be useful only as a screening tool.12
A variety of pitfalls are present in the projection of limb-length dis-crepancy in a child Many of these are directly related to the vagaries
of the various radiologic techniques Regardless of the method chosen, the same type of examination (e.g., scanography) should be performed
at each visit, preferably in the same radiographic suite to provide stan-dardization of technique
Skeletal age determination based
on comparison with the Greulich and Pyle atlas has traditionally been used along with lower-extremity radiographs to predict ultimate limb-length discrepancy in children This technique has two inherent flaws The first is that the bone age obtained is accurate only within approximately 12 months, and bone ages are notoriously inaccurate before the age of 6 years Ulti-mately, however, if evaluations are done sequentially over a number of years, the intrinsic inaccuracy is reduced For example, if distal femoral and proximal tibial epi-physiodeses were performed in an adolescent and the bone age deter-mination was in error by 12 months either way, the maximum resulting disparity would likely be no more than 16 mm (10 mm/yr for the dis-tal femur, 6 mm/yr for the proxi-mal tibial physis) From a practical point of view, this is probably not a serious concern
The second flaw is related to bone age determination on the basis of measurement of the left hand and wrist In conditions in which the left is the abnormal side (e.g., hemihypertrophy and hemi-atrophy), there may be a consequen-tial difference between the bone
Fig 1 The Galeazzi sign signifies shortening of the thigh segment, which may be
sec-ondary to hip dislocation or femoral shortening The Galeazzi test is performed with the
patient supine, hips flexed 90 degrees, and knees flexed The relative relationship of the
knee heights can then be assessed (Adapted with permission from Tachdjian MO:
Pediatric Orthopaedics, 2nd ed Philadelphia: WB Saunders, 1990, vol 1, p 326.)
Trang 4ages as determined on the left and
right sides Radiographs of both
hands should be obtained and
compared in this situation
Prediction of Discrepancy
In the skeletally mature individual,
there is no need to analyze
sequen-tial data, as the situation is static
The growing child, however,
pre-sents a challenge in predicting the
need for treatment and selecting
from the variety of treatment
op-tions The importance of obtaining
reproducible data cannot be
over-emphasized Currently, there are
four different methods
incorporat-ing three techniques for the
predic-tion of limb-length discrepancy: the
arithmetic method, the
Eastwood-Cole method, the Green-Anderson
growth-remaining method, and the
Moseley straight-line graph
meth-od.13-16
The potential accuracy of any of
these methods is enhanced by
hav-ing longitudinal data Obtainhav-ing
data at 6-month to yearly intervals
over a number of years is much
more helpful than using numerous
data points over a relatively short
time frame The same technique
should be used for each radiographic
assessment to avoid the vagaries of
magnification The fact that there are
a number of recognized patterns of
limb-length discrepancy, as
de-scribed by Shapiro,17further
empha-sizes the importance of minimizing
error
The arithmetic method, or
rule-of-thumb method, was first
de-scribed by White and evaluated by
Westh and Menelaus.13 It is based
on four assumptions about growth:
(1) boys stop growing at age 16;
(2) girls stop growing at age 14;
(3) the distal femoral physis grows
10 mm yearly; and (4) the proximal
tibia grows 6 mm yearly This
method is useful only during the
later years, not in young children
A potential disadvantage lies in using chronologic rather than skele-tal age, which may present prob-lems in assessing individuals who mature very early or very late
Eastwood and Cole16 published
a scheme using a graphic arith-metic method These data were confirmed with CT scanning and skeletal age measurements in mid-dle and late childhood Reference slopes indicate the most appropri-ate time for epiphysiodesis Using this technique, the authors pre-dictably achieved limb-length equality within 1 cm
The growth-remaining method
is based on growth tables pub-lished by Green and Anderson.15 Graphs relate the limb lengths of boys and girls to chronologic age and can be used to determine a childÕs growth percentile Other graphs demonstrate the remaining proximal tibial and distal femoral physeal growth and can be used to predict the effect of epiphysiodesis
Because only the most recent skele-tal age determination is used, any innaccuracy in its assessment will cause the resultant estimation of limb-length discrepancy to be prone to imprecision This method has the greatest longevity of use but is cumbersome due to the ne-cessity of referring to two sets of graphs
The straight-line graph method described by Moseley14is a distilla-tion of the Green-Anderson data graphically displayed in a straight line over time on a single graph It
is based on two principles: (1) a nomogram can be used to deter-mine the growth percentile from limb length and skeletal age, and (2) the growth of both limbs can be represented graphically by two straight lines The difference in slope between the long and short limbs indirectly represents the growth inhibition (or stimulation)
of the abnormal extremity An advantage of this method is that a
single-page graph represents the entire limb-growth history In addi-tion, the vagaries of interpreting skeletal age studies and their intrin-sic inaccuracy become less impor-tant over a number of estimations
In a recent study, Little et al18 compared the accuracy of the Anderson-Green, Westh-Menelaus, and Moseley methods of predicting limb-length discrepancy No im-portant differences were revealed Disparities of up to 2.5 cm in the foot height itself can be seen in patients with congenital limb shortening To date, no radio-graphic measurement method that provides a reproducible standing foot height has been described Any clinical measurement discrep-ancy should be added to the ulti-mate projected limb discrepancy Accuracy is enhanced by having
a single observer remeasure values
on all radiographs, regardless of the source Using measurements taken from different reference points creates unnecessary errors With accurate longitudinal data, the goal of producing reasonable limb symmetry with accuracy
with-in 1 cm should be readily achiev-able If the data are inadequate, inaccurate, or confusing, an epi-physiodesis should be avoided, and another method of limb equaliza-tion should be selected at skeletal maturity
Treatment Options
The broad spectrum of therapeutic options available for the patient with a limb-length discrepancy includes no treatment at all; simple shoe modification; shortening proce-dures, such as percutaneous epi-physiodesis (Fig 2) and intra-medullary shortening (Fig 3); lengthening procedures, and combi-nations thereof It is essential to establish the goals of treatment before embarking on any of these
Trang 5options In general, these goals are
equal limb lengths, normal axial
alignment with a level pelvis, and
enhanced function These goals
may be modified, depending on
var-ious clinical variables The patient
with a stiff knee or hip or weakness
of the involved extremity should be
left slightly short on that side to
allow the foot to clear the floor in
swing phase without the need for
circumduction or excessive Òhip
hike.Ó In patients with a fixed pelvic
obliquity, functional and actual limb
lengths may differ significantly If
the pelvic obliquity cannot be
elimi-nated, functional limb-length
equali-ty should be the goal
Data obtained by Gross1 and others suggest that projected dis-crepancies of less than 2 cm require
no treatment In a recent article, Kaufman et al2 demonstrated by gait analysis that subjects with a limb-length disparity of less than 2.0 cm had no greater gait asymme-try than the general population
Song et al3reported increased work done by the long side and greater vertical displacement of the center
of body mass in patients with dis-crepancies greater than 5.5% com-pared with the opposite limb
In general, patients whose ulti-mate inequality will be in the range
of 2 to 6 cm should undergo a
short-ening procedure, either by epiphys-iodesis or femoral shortening There are several potential excep-tions One is the patient in whom the short extremity has a major angular deformity In such a case, simultaneous deformity correction and lengthening should be consid-ered Another possible exception is the patient with pathologically short stature in whom further height reduction would compromise func-tion Yet another potential excep-tion is the patient with shortening below the knee who presents either
at maturity or too late for an epi-physiodesis and in whom contralat-eral femoral shortening would
Fig 2 A,Percutaneous drilling of the dis-tal femur is performed from both the
medi-al and the latermedi-al sides B, Curettage is
then performed to remove all growth
carti-lage C, An anterior approach to the
proxi-mal fibular physis provides direct visual-ization and avoids potential peroneal nerve injury The incision can then be utilized to drill and curette the lateral proximal tibial
physis D, As in the distal femur, both
medial and lateral approaches to the proxi-mal tibial physis are recommended to
ensure symmetrical growth arrest E,
Introduction of contrast material confirms adequate physeal excision.
Trang 6duce additional knee-height
asym-metry A review of the literature
indicates that there is no functional
or cosmetic disability as a result of
knee-height disparities of less than 4
cm If the difference is greater than
this, lengthening of the involved
tibia may be preferable
The patient with a discrepancy
exceeding 5 to 6 cm is best treated
by limb lengthening or a
combina-tion of limb lengthening and
con-tralateral shortening Limb
abla-tion and/or prosthetic fitting
should be reserved for patients
whose problems are unmanageable
by current surgical techniques
Shoe Modification
A shoe lift remains an excellent treatment for small discrepancies
Unfortunately, even with the new lightweight orthotic materials, all shoe lifts render the sole stiff
Tapering at the toe is necessary to approximate normal gait This is the least morbid and least expen-sive method of limb-length
equal-ization and is preferable for patients with discrepancies of less than 2.0
to 2.5 cm Nearly half of the dispar-ity can be accommodated inside the shoe, which may be sufficient to provide adequate patient comfort Although modern orthotic technol-ogy has decreased shoe-lift weight, most patients with larger discrepan-cies shun the lift because of cosme-sis and prefer a surgical option despite the potential morbidity
Shortening Procedures
Epiphysiodesis and acute femoral shortening are both length-reducing procedures In the growing child with adequate longitudinal data, normal axial alignment, and a pro-jected discrepancy of between 2 and 5 cm, epiphysiodesis remains the procedure of choice Various techniques have been described, including epiphyseal stapling and the Blount and Phemister tech-niques
Epiphyseal stapling should be used cautiously In order to pro-duce physeal arrest, three medial and three lateral staples are placed
in the distal femur and the proximal tibia The most common complica-tion reported is staple extrusion.19 The method currently preferred
is the percutaneous technique ini-tially reported by Canale et al.20,21 Small medial and lateral physeal incisions allow percutaneous drilling, followed by physeal curet-tage under image intensifier con-trol (Fig 2) Postoperative immobi-lization is not required Excellent and reproducible results have been achieved with this technique.21-23 The choice of limb segment (i.e., distal femur or proximal tibia or both) should be selected primarily
on the basis of the location of the contralateral shortening If the shortening is idiopathic, both limb segments will be involved Under these circumstances, knee height
Fig 3 In intramedullary shortening, the intramedullary canal is first reamed over a guide
wire A cam saw of appropriate size is then introduced into the femoral diaphysis (A) and
deployed gradually while being rotated to produce an osteotomy (B) The saw is then
moved the appropriate distance to achieve the amount of shortening desired proximally,
and the procedure is repeated (C) The saw is removed, and a J-shaped osteotome is
inserted to split the intercalary segment (D) This must be done twice, ideally at 180
degrees with respect to each longitudinal osteotomy (E) The guide wire is reintroduced,
the femur is shortened, and the intramedullary nail is inserted (F).
Trang 7symmetry will be maintained if
epiphysiodesis is performed on
both the distal femur and the
proxi-mal tibia
Acute tibial shortening has major
potential complications, including
nonunion and compartment
syn-drome,24,25which preclude its
com-mon use for limb-length
equaliza-tion Femoral shortening is useful
for patients who present after
matu-rity and for those with insufficient
data or inadequate growth
remain-ing for an epiphysiodesis The two
basic described techniques are closed
intramedullary shortening, as
de-scribed by Winquist26and Kempf et
al,27and open subtrochanteric
short-ening performed with use of either a
blade plate or large-fragment plate
fixation An intramedullary saw is
used for the first technique, with
dia-physeal osteotomies, splitting of the
intercalary segment, and insertion of
a locked intramedullary rod (Fig 3)
This method is technically
de-manding, requiring familiarity with
the instrumentation Its success
depends on several anatomic
as-sumptions that may not be true The
cam-deployed saw works in a
circu-lar fashion, but the femur is not
always cylindrical and of uniform
thickness throughout its
circumfer-ence A small incision may be
re-quired to complete the osteotomy
There are concerns as well about the
use of this technique in adolescents
because of reports of osteonecrosis of
the hip after femoral nailing.28,29
The open subtrochanteric
tech-nique is generally easier than the
diaphyseal one Fixation can be
achieved by using either a blade
plate or a contoured conventional
plate (Fig 4) Nordsletten et al30,31
have demonstrated a possible
max-imum of 10% length reduction in
middiaphyseal shortening as
opposed to subtrochanteric
short-ening In their experience, thigh
muscle strength never returned to
normal in patients with diaphyseal
shortening greater than 10% This
suggests that the open proximal technique of shortening may be a more physiologically sound proce-dure than closed intramedullary diaphyseal shortening
Limb Lengthening
Lengthening has significantly evolved over the past decade in North America due to the introduc-tion of the Ilizarov technique.32,33 The biologic principles of gradual incremental distraction have con-tributed greatly to the ability to form excellent bone in the distrac-tion gap while avoiding the prob-lems of the need for bone graft and plate fixation, which plague the Wagner and other techniques
Despite the improvements in gradual-distraction lengthening techniques, the complications of
limb lengthening exceed those of epiphysiodesis or acute shortening These include joint contracture, joint subluxation or dislocation, muscle weakness, vascular injury, nerve palsy, bone regenerate defor-mation, and pin-site infection.34,35 Limb lengthening is indicated for length discrepancies exceeding
5 to 6 cm and those associated with significant angular and/or
rotation-al deformity of the short extremity Limb lengthening can be easily combined with epiphysiodesis as part of the overall strategy for man-agement of limb-length inequality For example, if a patient with con-genital limb hypoplasia has a pro-jected discrepancy of 18 to 20 cm and is a reasonable candidate for limb elongation, two lengthenings plus a contralateral epiphysiodesis may be a more reasonable strategy than three lengthening procedures
Fig 4 A,Preoperative scanogram of a skeletally mature 28-year-old woman with 3.3 cm
of left femoral shortening due to a previous fracture B, Open subtrochanteric shortening
of the right femur was performed Fixation was achieved with use of a 90-degree adoles-cent blade plate.
Trang 8The currently utilized technique
involves a percutaneous osteotomy,
with care to avoid periosteal
strip-ping, followed by gradual
incremen-tal distraction.32,33 This is
accom-plished with the use of external
skeletal fixation Lengthening with
temporary external fixation over an
intramedullary nail may be used in
selected circumstances (Fig 5).36
The external fixator may be either a
multiplanar (circular) or a uniplanar
(cantilever) type Bone fixation may
be achieved with transosseous
ten-sioned wires, half pins, or a
combi-nation of both, depending on the
fix-ator type
Circular, Ilizarov-type fixators
allow application to almost any
limb segment or size and can be
adjusted to correct angular,
rota-tional, and translational deformi-ties as well as to achieve lengthen-ing (Fig 6) The devices can be extended to adjacent limb seg-ments when necessary to protect potentially unstable joints during lengthening and to avoid tendon contracture However, Ilizarov fix-ators are neither user- nor patient-friendly There is a steep learning curve before one can consistently avoid iatrogenic errors and major complications related to their use.34 Uniplanar devices are easier to apply and are usually well tolerated
by the patient Due to their configu-ration, they have some limitations
in application in small patients and
in patients with multifocal or multi-planar deformities (Fig 7) Align-ment adjustAlign-ment in the pediatric
patient usually requires general anesthesia Lengthening of the fe-mur with a uniplanar device causes elongation along the anatomic bone axis, producing medialization of the knee.33,36 Because the extent to which this occurs is dependent on the extent of lengthening, this factor should be considered before choos-ing a cantilever device
Lengthening over an intra-medullary nail probably has its greatest application in the mature patient The advantage of this tech-nique is limiting the time of exter-nal fixation.36 Once the desired length has been achieved, the nail is locked distally, and the external fix-ator is removed The most signifi-cant potential risk is intramedullary sepsis due to communication of
Fig 5 A,Radiographs of a 21-year-old man who was injured in a lawn-mower accident at age 2 Multiple surgical procedures, including
a left knee arthrodesis, resulted in an 8-cm limb-length inequity B, Lengthening of the femur over a proximally locked femoral nail was initiated through a subtrochanteric osteotomy A cantilever fixator was used C, Radiographic appearance at the conclusion of gradual distraction to achieve lengthening by 6 cm The nail was locked distally, and the external fixator was removed D, Radiographic
appear-ance after consolidation of the distraction gap (Courtesy of John E Herzenberg, MD, Baltimore.)
Trang 9external fixator pins with the
intra-medullary device Juxta-articular
deformity (such as in the distal
femoral metaphysis) cannot be
easi-ly corrected with this technique
because the nail ascends within the
femur during lengthening
How-ever, diaphyseal deformity can be
easily corrected acutely prior to nail
insertion
A completely implantable
inter-nal lengthening device would be
ideal The Albizzia nail works by a
ratchet mechanism.37 The nail is
implanted and locked proximally
and distally Rotation of the
pa-tientÕs lower extremity creates
dis-traction with an audible click This
device is currently under
develop-ment and is considered
experimen-tal in North America A hydraulic
mechanism would, in theory, be advantageous to eliminate the rota-tion necessary with this system
Controversies in Limb Lengthening
The ability to lengthen a limb is now no longer limited by the
abili-ty to produce bone that will heal reliably Soft tissues and joint sta-bility currently limit the asta-bility to lengthen a limb and produce a functionally as well as cosmetically acceptable result The prior histori-cal constraints of 15 to 18 cm of maximum lengthening may no longer be valid
Patients with severe fibular and tibial hemimelia are probably still
best treated by limb ablation in in-fancy For the patient with fibular hemimelia and a foot with fewer than three rays, there are currently
no effective means of producing a reasonably functional weight-bear-ing foot Patients with acceptable foot function and a moderately mobile ankle can be treated with soft-tissue releases, resection of the fibrous fibular anlage (when pres-ent), Achilles tendon lengthening, and subsequent use of an articulated ankle-foot orthosis until the length discrepancy becomes unmanageable (6 to 8 cm), at which time the first tibial lengthening is performed The child can be reevaluated to plot the developing discrepancy, and a sec-ond lengthening and contralateral epiphysiodesis can be done if neces-sary The important feature of these patients is not the presence or ab-sence of the fibula, but rather the morphology and potential function
of the foot and ankle
A patient with tibial hemimelia and an absent or dysfunctional knee extensor mechanism is best treated by an early knee disarticu-lation Limb reconstruction can be
a viable option if the proximal tibia
is present (as determined by clini-cal examination and ultrasound or magnetic resonance imaging), the knee actively extends and is rea-sonably stable, and the foot can be made functional by early compre-hensive soft-tissue release Ulti-mately, symptomatic ankle insta-bility in either tibial or fibular hemimelia can be managed with an ankle arthrodesis without sacrific-ing the foot
Severe forms of proximal fe-moral focal deficiency in which there is little femur present (type D
in the Aitken classification system)
or in which the hip cannot be ren-dered stable are still not amenable
to lengthening However, if hip stability can be achieved, femoral lengthening can be done If the foot is at the level of the
Fig 6 A,Preoperative radiograph of a skeletally mature woman with Ollier disease and a
14-cm limb-length inequality Circular external fixation was used to gradually correct the
proxi-mal and distal tibial deformities and to lengthen the tibia by 8 cm B, Teleradiograph at the
completion of the tibial lengthening (Subsequent femoral lenghtening is illustrated in Figure 7.)
Trang 10eral knee and the ankle has a
func-tional range of active motion, a Van
Nes rotationplasty may provide an
alternative to foot ablation
Each limb-lengthening
proce-dure should probably be confined
to no more than 15% to 20% of the
limb-segment length The rate of
distraction should be adjusted
according to the appearance of the
regenerate bone formation as well
as the range of motion of adjacent
joints The Ò0.25 mm four times a
dayÓ guideline need not be fol-lowed rigidly The potential com-plications of joint stiffness due to cartilage injury and/or musculo-tendinous contracture can be avoided by careful assessment dur-ing the distraction phase.38,39 Limb function should not be sacrificed in the attempt to gain excessive length
Residual discrepancy can be treated
by additional lengthening at a later date, shortening of the contralateral extremity, or both
Summary
The management of the growing patient with limb-length inequality requires careful assessment, se-quential limb-length evaluations, and formation of a strategy based
on the individual patientÕs needs Treatment may involve a single procedure or a series of proce-dures, depending on the etiology and magnitude of the discrepancy and associated deformities
A
E
Fig 7 A,Photograph of the patient in Figure 6 after tibial lengthening and deformity correction but before initiation
of femoral lengthening and correction of
the distal femoral valgus deformity B,
Anteroposterior and lateral radiographs
of the femur after acute correction of the distal femoral deformity and initiation of
gradual distraction C and D,
Antero-posterior and lateral radiographs at the
completion of treatment E, Final
appear-ance of the patient at the completion of limb-length equalization The original shoe lift is shown on the right.