Correction
of Large Bilateral Tibia Vara
with the Ilizarov Method
by S.
Robert Rozbruch, MD; Arkady Blyakher, MD; Stephen B. Haas, MD; Robert
Hotchkiss, MD
Limb Lengthening Service, Knee Service
Department of Orthopaedic Surgery, Hospital for Special Surgery
Weill Medical College, Cornell University
Abstract
An
adult patient with massive bilateral tibia vara as a result of neglected
infantile Blount's disease is presented. Correction of the deformities
was performed with a tibia and fibula osteotomy and gradual correction
using circular external fixation. This represents very early American
experience with the Ilizarov method. Ten year clinical and radiographic
follow up is presented.
Introduction:
Blount's Disease in the adult is a sequel of either the infantile,
juvenile, or adolescent types depending on the age of onset.1
Disordered growth of the proximal medial physis and metaphysis produces
a localized varus deformity. In addition there is usually a medial
tibial torsion deformity. In severe neglected cases, there may be
ligamentous laxity, a large varus deformity, extreme sloping and depression
of the posteromedial plateau of the tibia, and hypermobility of the
medial meniscus.14
Extreme medial deviation of the mechanical axis line leads to abnormal
stress transmission across the knee, and this is expected to cause
knee pain and progressive degenerative arthritis in adulthood. Zayer,19
in a report of 133 knees in 86 patients with Blount's disease, found
that in individuals under 30 years of age there was none with degenerative
joint disease, whereas in patients over 30 years of age, 41% had radiographic
evidence of degenerative changes. Increasing varus deformity predisposed
to degenerative change.
A variety of methods have been used to correct the tibia vara. These
include acute correction of the deformity with various oblique or
dome shaped osteotomies with a number of different fixation techniques.
Review of the literature 2,8,13,17
reveals a high percentage of fair and poor results. Acute angular
and rotational correction of a large deformity with internal fixation
is subject to imprecision, nerve palsy, and compartment syndrome.
Limited weight bearing is also required in the postoperative period.
Closing wedge osteotomies often add to preexisting limb shortening
and compromise metaphyseal bone stock.
The gradual correction of deformity using the principles of distraction
osteogenesis was introduced by Ilizarov.6
This method has many advantages over more traditional methods. This
case represents very early American experience with the Ilizarov method
for correction of massive bilateral varus deformities in an adult
from neglected BlountŐs disease with a ten-year followup.
Case Report:
A
22 year-old woman presented with severe varus deformities of both
legs (Fig.
1A). She was able to ambulate but did so with a limp and with
pain in the knees. She had surgical treatment as a young child in
Africa but was not aware of the details. On physical examination,
using a goniometer, the right leg varus measured 70° and the left
leg varus measured 75°. Range of motion of both knees was 0°
to 130°. There was full mobility of the hips. Preoperative supine
radiographs showed a right femorotibial angle of 40° varus (Fig.
1B) and a left femorotibial angle of 48° varus (Fig.
1C). Both sides were consistent with type VI infantile tibia vara
according to the classification of Langenskiold and Riska.7
Standing radiographs showed a femorotibial angle on the right of 55°
varus and on the left of 62° varus.
Bilateral proximal tibia osteotomies, proximal fibula resections of
5 centimeters and peroneal nerve decompressions were performed. Bilateral
Ilizarov frames were applied to match the varus deformities. A postoperative
right-sided extensor hallucis longus palsy was noted. Gradual adjustment
of the frames was started on postoperative day seven. The speed of
correction was determined so that the bone at the concavity of the
deformity was being distracted at 1 mm per day. Weight bearing as
tolerated was encouraged throughout the treatment. At the end of the
correction she was ambulating full weight-bearing in the bilateral
frames. (Fig
2) At three and one-half months after the index procedure, the
patient was taken back to the operating room for excision of prominent
bone from the left tibia and frame modification. At five and one-half
months after the index procedure, the right Ilizarov frame was removed.
At six and one-half months, the left Ilizarov frame was removed. The
left proximal tibia was subsequently noted to have a stiff nonunion,
and further surgical treatment was felt to be necessary. At seven
months following the index procedure, the Ilizarov frame was reapplied
to the left leg for the purpose of stabilizing and compressing the
nonunion site. The nonunion was not surgically exposed and was not
bone grafted. Three months later the left sided frame was removed.
At one year and five month follow-up following the index procedure,
she was ambulating well. She complained of a mild occasional ache
in the right knee. Range of motion (ROM) of the right knee was 0°
135° and the left knee was -3° 135°. At
two-year followup, the patient complained of no pain. ROM of the right
knee was 0° 130° and the left knee was -5° to 125°.
A mild lateral thrust was noted bilaterally, but the left side was
more pronounced. Erect leg radiograph demonstrated complete bony healing
of the osteotomies. The left leg was noted to be 8 mm longer than
the right leg. Mechanical axis deviation was 31 mm medial to the midline
on the right side and 44 mm medial to the midline on the left side.
Lateral distal femoral angle was 83° on the right and 77°
on the left. Medial proximal tibial angle was 74° on the right
side and 65° on the left side11
(Fig 3A).
At ten-year followup from the index procedure is ambulating without
assistance. She complains of mild and intermittent pain in both knees
that responds to the occasional short-term use of non-steroidal anti-inflammatory
medications. Knee alignment is visibly normal. (Fig.
3B) No significant coronal or sagittal plane instability is noted.
Standing radiographs (Fig.
3C) demonstrate a femorotibial angle of 2° varus of both right
and left sides. Knee joint spaces are maintained, and bony remodeling
has occurred. Lateral radiographs (Fig.
3D, Fig.
3E) demonstrate the absence of deformity and advanced bony remodeling.
Discussion:
This patient is an example of a young adult presentation of a neglected
case of bilateral infantile Blount's disease. Oyemande10
reported 25 Nigerian adolescent patients with advanced tibia vara.
Fifteen of the patients had bilateral deformities. They were treated
with closing wedge osteotomies, acute correction through an open technique,
and casting. Complications reported were 4 residual deformities, one
osteomyelitis, one wound necrosis, and several large keloid scars.
The closing wedge osteotomies led to further shortening.
Medial mechanical axis deviation and increased stress on the medial
joint compartment is thought to be the etiology of Blount's disease
and a contributing factor to progressive medial compartment degeneration.
Zayer19 found
that 11 of 27 knees in patients with Blount's disease over age 30
had osteoarthritic changes. Increasing varus predisposed to degenerative
change, but the relationship was not constant. The legs with smaller
medial proximal tibial angles were predisposed to degenerative change,
and medial proximal tibial angles less than 73° were only seen
in knees with osteoarthritis. The patient in the current report had
severe sloping and depression of the medial plateau. While this was
not addressed in this patient, there are authors who have advocated
elevation of the plateau. Zayer18
reported hemicondylar osteotomy in two 15 year-old patients with neglected
Blount's disease. At 6 year follow up, he reported good results and
recommended this technique for late neglected cases.
Gregosiewicz et al5
advocated a double elevating osteotomy for severe cases of tibia vara.
They performed an acute closing wedge osteotomy in the metaphysis
and used this wedge of bone to fill an opening wedge osteotomy through
the medial physis. This was done in children, average age 8, and was
stabilized with crossed wires and a long leg cast. This improvement
of the congruence of the articular surface in addition to mechanical
axis realignment may help protect the knee from future degeneration.
Disadvantages of internal fixation after proximal tibial osteotomy
include the lack of postoperative adjustability, difficulty in translating
the distal fragment laterally, and the need for limited weight bearing
or casting. The inability to obtain a standing hip to ankle radiograph
during surgery limits the precision of an intraoperative correction.
With external fixation stabilization, the position can be changed
acutely or gradually after a standing hip to ankle radiograph is obtained
and the appropriate mechanical axis analysis is performed.11
Acute deformity corrections and stabilization with external fixation
has been reported by several authors. Miller et al9
reported the use of an inverted arcuate osteotomy, acute correction,
and stabilization with a hybrid external fixator in 12 patients. The
average deformity correction obtained was 21.7°. They reported
no nerve palsies or compartment syndromes. Smith et al15
reported on the use of a gigli saw percutaneous osteotomy, acute correction,
and stabilization with an Orthofix unilateral external fixator in
19 patients with an average weight of 258 lbs. The average correction
performed was 27.6° and the time to healing was 141 days. At union
the average mechanical axis was 1.9° of varus. Four of their patients
had adjustment of the fixator in the postoperative period. One patient
had a peroneal nerve palsy that resolved.
Disadvantages of acute deformity correction may include an increased
risk of neurovascular insult and compartment syndrome, particularly
with large deformities. Several authors have reported the use of gradual
deformity correction with external fixation for tibia vara. Price
et al12 reported
on the use of dynamic axial external fixation in a group of 23 patients
obtaining an average of 20° of correction. De Plabos et al4
reported on the use of gradual correction in 10 patients. An average
of 15° of angular correction was obtained at the proximal tibia
osteotomy. The average time in the frame was 12 weeks. Stanitski et
al16 reported
on the use of gradual correction with circular external fixation for
17 obese children. The average preoperative angular deformity was
27° of varus and all patients achieved alignment within 5°
of normal. Three patients had leg length discrepancy and underwent
an average of 3.5 cm of simultaneous lengthening. The time in frame
was 12 weeks for those patients treated without lengthening and 16.9
weeks in those requiring lengthening. There were no nerve palsies
or compartment syndromes.
While there is a general consensus that correction of the varus deformity
in Blount's disease is desirable, there have been many methods advocated.
These include open or percutaneous osteotomy in the metaphysis of
the proximal tibia, opening or closing wedge correction, acute or
gradual correction, stabilization with internal or external fixation,
and opening wedge correction through the proximal tibia physeal area.
The use of a percutaneous osteotomy in the metaphysis and gradual
correction of a large deformity with an external fixator has many
advantages. The osteotomy is minimally invasive and does not require
extensive soft-tissue stripping, improving the bony healing potential.
Complications of osteomyelitis, wound dehiscence, and large keloid
scar formation should be less likely. Benefits of the use of external
fixation as the method of stabilization are that it allows increased
weight bearing and lateral translation of the distal fragment along
with the angular correction. Another benefit is the feature of postoperative
adjustability after a standing hip to ankle radiograph is obtained
and the mechanical axis analysis is performed. The use of a gradual
correction may decrease the likelihood of neurovascular insult and
compartment syndrome particularly in a patient with a massive deformity
as in the current report. Gradual correction should be relatively
safe in a Blount's disease patient with a massive varus deformity
along with procurvatum and internal tibial torsion. Another advantage
of gradual correction with a frame is the possibility for limb lengthening
if needed to correct length discrepancy. Opening wedge correction
prevents further shortening and loss of bone stock.
In the current patient, correction of large varus deformities was
performed. The corrections were 53° and 60° on the right and
left sides respectively. Simple knee radiographs were used preoperatively
and during the correction, limiting a comprehensive deformity analysis11
Anatomic femorotibial measurements were used as a result. Although
the corrections were large and the cosmetic and functional result
very good, there is still some mechanical axis deviation in both lower
limbs. The use of erect leg radiographs that include the hip, knee,
and ankle and the use of a mechanical axis analysis of the deformity
and correction 11 are currently used. This may result in a more accurate
and critical deformity correction and analysis of the result. In the
current case, one may consider additional intervention in this now
32-year-old patient. This would be a difficult recommendation since
she is pain-free and has excellent function. Surgical options that
could correct residual deformity include another bilateral osteotomy
to centralize the mechanical axis line may help prevent progression
of osteoarthritis. In addition, an elevation of the sloped medial
tibial plateau with an acute opening wedge correction may be beneficial
for improving the force distribution across the knee.18
Both femora have valgus deformities. The left side is greater with
a lateral distal femoral angle of 77° than the right side with
a lateral distal femoral angle of 83° (normal is 85° to 89°).11
One might consider a distal femoral osteotomy to correct the femoral
valgus particularly on the left in addition to a tibial osteotomy
to correct additional varus. This would put the knee joint line perpendicular
to the weight-bearing axis and may help prevent progression of arthritis.
Complications encountered in the present case included a right extensor
hallicus longus palsy noted immediately after surgery. This was probably
related to surgical technique during the proximal fibula resection
and peroneal nerve decompression. The current recommendation would
be for a middle fibula resection or oblique osteotomy without nerve
decompression. If during the gradual correction, peroneal nerve symptoms
and signs occur, a secondary nerve decompression would be performed.
A stiff nonunion of the left proximal tibia was encountered which
required reapplication of the Ilizarov frame for compression. Uneventful
bony union occurred after 3 months. Compression of a stiff nonunion
without surgical exposure or open bone grafting is another helpful
application of the Ilizarov method.3,6
This case represents the very early American experience with Ilizarov
method for correction of very large bilateral varus deformities in
a young adult with neglected Blount's disease and ten year clinical
follow up is presented. There has been an evolution in the method
of deformity analysis, which may explain the imperfect although greatly
improved position.
Legend of Figures:
Fig. 1 A-C
(A) Preoperative front view showing large varus deformities of both
legs.
(B) Preoperative supine radiograph of the right knee.
(C) Preoperative supine radiograph of the left knee.
Fig. 2
Front view of both legs in Ilizarov frames following correction of
the deformities.
Fig. 3 A-E
(A) Erect leg radiograph two years following surgery.
(B) Front view of legs ten years following surgery .
(C) Standing radiograph of both knees ten years following surgery.
(D) Lateral radiograph of right knee ten years following surgery.
(E) Lateral radiograph of left knee ten years following surgery.
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