Correction of Lower Extremity Deformities by Distraction Osteogenesis

(originally at http://www.limblength.com/pubs/articles/distost/distost.htm )

Advances in Orthopaedic Surgery | ORIGINAL ARTICLES

Correction of Lower Extremity Deformities by Distraction Osteogenesis

Mark T. Dahl, M.D.

Gillette Children's Hospital, St. Paul, Minnesota; Fairview Riverside Medical Center, Minneapolis, Minnesota; and Shriners Hospital for Crippled Children, Minneapolis, Minnesota

ABSTRACT

Lower extremities (n = 171) with various deformities were gradually corrected by distraction osteogenesis. One of two fixators (llizarov or DeBastiani) was used depending on the features of the deformity. Careful preoperative planning, patient education, precise surgical technique, and sustained postoperative care were essential for success. Complications were frequent, particularly pin site and soft-tissue sequelae, but they rarely prevented a successful result. Distraction osteogenesis offers a wide variety of correction possibilities for severe lower extremity deformities.

INTRODUCTION

In recent years, the primary technical advances in limb lengthening and deformity correction have been in the development of external fixators that allow for weightbearing and maintenance of joint function during gradual bone and soft-tissue regeneration. A variety of available devices include Wagner's
and DeBastiani's monolateral frames, and the multiplanar systems of Monticelli, Fischer, and Ilizarov.

The introduction of each fixation device adds new principles and operative techniques for treating skeletal deformities. Wagner's fixator provides monolateral fixation for long-bone lengthenings (Wagner, 1978). Ilizarov's transfixion wire/ring system provides for multilevel, multiapical, and juxta-articular corrections (Ilizarov, 1990). DeBastiani's rigid frame has a telescoping feature that allows dynamic loading (DeBastiani et al., 1987). Fischer's fixator combines circular and monolateral features with partial rings and the use of wires or half pins (Fischer, 1983).

The primary biological advancement in limb lengthening is Ilizarov's concept of bone and soft-tissue regeneration in a widening distraction gap under controlled mechanical means through a subperiosteal corticotomy (Aronson, 1990). The creation of bone by intramembranous ossification was pioneered by Ilizarov, and as scientific and clinical knowledge of Ilizarov's methodology grows, a broad spectrum of lower extremity applications is occurring.

This article describes lower extremity applications of the Ilizarov and DeBastiani methods. The case examples describe and illustrate several of these uses, depending on the location of the deformity and the difficulty of the correction.

DEFORMITY CORRECTIONS

Since 1985, distraction osteogenesis has been used by the author to treat 171 various lower extremity orthopedic problems. The most common use of the DeBastiani device was for femoral lengthenings without significant angular deformity. The Ilizarov apparatus was widely used for complex, multilevel, multiangular, and juxta-articular applications. These applications, in order of frequency, involve: limb lengthening, lengthening with angular correction, angular correction alone, treatment of nonunions, and treatment of congenital tibial pseudarthroses. There were a few cases involving recalcitrant club feet and severe foot deformities. Twelve patients were also treated with upper
extremity corrections (Coony & Dahl, this issue, p. 150).

INDICATIONS

Indications for using the llizarov or DeBastiani techniques in adults include fracture repair (diaphyseal and juxta-articular); repair of postraumatic problems such as nonunions, malunions, segmental bone defects, and chronic osteomyelitis; and resolution of joint contractures. Indications in children include limb lengthening, limb lengthening with deformity correction, and deformity correction through bone or soft tissue.

 

THE CLINICAL "PROCESS"

This treatment is not a procedure,
but a process, occurring and changing over weeks and
months. Understanding the need for careful preoperative planning,
meticulous technique, and continued follow-up evaluation during
the process of distraction are necessary for successful outcomes.
Combining these principles with appropriate expectations on the
part of the surgeon and patient is necessary.

When planning a correction, a
multitude of factors must be considered, including the patient's
age, etiology, and extent of deformity. Deformities must be classified,
listed, and their magnitude measured, before initiating the planning
process. Comprehensive treatment involving 1) preoperative planning,
2) patient education, 3) precise surgical technique, and 4) postoperative
care is essential.

1. Preoperative planning follows
a detailed musculoskeletal history and examination. Full-length
standing X-rays and multiple views are necessary to analyze mechanical
axis. Special studies such as tomography, magnetic resonance
imaging, and radioisotope scanning are occasionally necessary.
Overlay drawings and computer graphics are also used to assist
in apparatus design and preassembly. Before surgery, it is critical
to understand the patient's symptoms and expectations.


2. Through patient education,
a detailed course of events can be presented that prepares the
patient and family both physically and emotionally for the prolonged
treatment. Strict patient compliance and rapport throughout this
difficult process is vital.


3. The surgical techniques of
frame design and application, subperiosteal corticotomy, and
proper pin and wire insertion, all require instruction and practice.


4. Postoperative care during
the gradual correction process requires a coordinated approach
between the surgeon and a multidisciplinary team that includes
the limb-fixator nurse, physical therapist, and many other team
members. Weekly clinic visits during lengthening or deformity
correction are necessary. Monthly visits occur during the healing
phase. Physical therapy and graded return to normal function
are continued throughout treatment.


 

The fixators are removed on an
outpatient basis. Anesthesia is not used during removal of the
DeBastiani device, but a general anesthesia is used when removing
the Ilizarov device.

LIMB LENGTHENING

The DeBastiani and Ilizarov methods
utilize similar biological principles for stimulating bone growth.
The variations in design and surgical application make the devices
technically quite different. The Ilizarov fixator appears to have
greater versatility in correcting complex deformities, while the
DeBastiani device offers greater application simplicity and patient
tolerance.

In discrepancies greater than
5 cm, or less than 5 cm when associated with an angular deformity
or in a short-statured individual, limb lengthening is considered.
There were 117 such lengthenings performed; 65 of these were femora
and 52 were tibiae. Of these, 39 were completed using the DeBastiani
device, while 78 were corrected with the Ilizarov apparatus.

Case 1 A
17-year-old girl with an acquired 9-cm discrepancy was treated
with a lengthening of 8 cm (Fig. 1). Treatment time was 7 months.
The slight varus deviation is not evident clinically. Articular
function has been maintained and the discrepancy reduced to 1
cm.

Figure 1.

Case 2 An 8-year-old boy with congenital posteromedial
bow of the tibia and a discrepancy of 5 cm was treated with a
single-level tibial angular correction and lengthening (Fig. 2).
Treatment time was 24 weeks. The 3-year follow up X-ray shows
complete lengthening remodeling.

Figure 2.

ANGULAR DEFORMITY CORRECTION

Conventional subtraction osteotomy
is usually preferred for moderate angular deformities but limits
of safety and lack of adjustability exist. Gradual distraction
osteotomies with external fixation offer certain advantages: the
deformities of length, translation, and rotation can also be corrected;
nerves and surrounding soft tissues can slowly accommodate to
the new position; and progressive clinical evaluation "fine-tuning"
of the correction is possible. Twenty-seven segments with deformities
secondary to Blount's disease, dysplasias, degenerative knee arthrosis,
and partial growth plate arrest about the knee or ankle were treated.

Case 3 A 6-year-old boy with infantile tibia vara, resulting
in severe angular and rotational deformity, was treated bilaterally
(Fig. 3). Fixation time was 10 weeks followed by 4 weeks of casting.

Figure 3.

Case 4
A 22-year-old woman with a posttraumatic tibial malunion was corrected
with oblique planar

hinges (Fig. 4).

Figure 4.

NONUNIONS

llizarov has introduced new concepts
in the diagnosis and management of nonunions. Catagni and associates
have further described these concepts for practical applications
(Catagni, 1991). Twenty-three nonunion/malunions have been treated
including five with massive bone loss, seven hypertrophic, five
atrophic, and six congenital tibial pseudarthrosis. Union was
achieved in all but one, a 29-year-old female with multiply-operated,
congenital tibial pseudarthrosis.

Case 5 A
28-year-old woman with bilateral tibial nonunions, following a
boating accident, was treated with compression-distraction osteosynthesis
(Fig. 5). Twenty-four weeks of fixation were required.

Figure 5.

 

Case 6 A
13-year-old girl with multiply-operated, congenital tibial pseudarthrosis
was treated with resection and compression of the nonunion and
proximal lengthening (Fig. 6). A length of 7 cm was achieved and
union was present at 2 years posttreatment.

Figure 6.

COMPLICATIONS

A spectrum of complications with
varying frequencies and severity occur with distraction osteogenesis
techniques (Dahl, in press; Paley. 1990). Pin-site inflammations,
the most common minor complication, occur at 5% of the sites once
skill at insertion techniques is achieved. In limb-length surgery,
the major complications of axial deviation, delayed union, fracture,
joint subluxation, and contracture were prevalent in the first
40 applications.

This complication rate and severity
decreases slowly with experience, as demonstrated in the author's
learning curve (Fig. 7) for limb-lengthening complications (Dahl,
in press).

CONCLUSION

Current principles of distraction osteogenesis are built upon the observations and experiences of llizarov. The complexity of the deformities treated are high; however, the continued application and evolution of these methodologies
is occurring. In the applications mentioned, the course of treatment has been rewarding and has satisfied the patient and surgeon in all but a few cases. Despite early enthusiasm, these difficult techniques require a cautionary approach as their role in the
management of severe lower extremity deformities is still being defined.

 

SUGGESTED READING /
REFERENCES

Aronson J, Good B, Stewart
C, Harrison B, Harp J. Modern techniques in limb lengthening:
Preliminary studies of mineralization during distraction osteogenesis.
Clin Orthop 1990;250:43-49.

Catagni M. Operative
principles of llizarov fracture treatment-nonunion osteomyelitis-lengthening
deformity correction. In: Association for the Study and Application
of llizarov's Method (ASAMI Group). Baltimore: Williams &
Wilkins, 1991: 14-15.

Dahl M. Complications
of limb lengthening-A learning curve. Clin Orthop, in press.

DeBastiani G. Aldegheri
R, Renzi-Brivio L. Trivella G. Limb lengthening by callus distraction
(callotasis). J Pediatr Orthop 1987;7:129.

Fischer DA. Skeletal
stabilization with a multiplane external fixation device. Clin
Orthop 1983;180:50.

Ilizarov GA. Modern
techniques in limb lengthening: Clinical application of the tension-stress
effect for limb lengthening. Clin Orthop 1990;250:8-26.

Paley D. Modern techniques
in limb lengthening: Problems, obstacles, and complications of
limb lengthening by the llizarov technique. Clin Orthop 1990;21(4):667691.

Wagner H. Operative
lengthening of the femur. Clin Orthop 1978;136:125.

Advances in Orthopaedic
Surgery, November/December 1992, Vol. 16, No. 3	149