blount's disease (textbook)

8/12/2019 Blount's Disease (Textbook)

http://slidepdf.com/reader/full/blounts-disease-textbook 1/17

ORTHOPAEDIC & TRAUMATOLOGY TEXTBOOKHASANUDDIN UNIVERSITY MAY 2014

BLOUNT’S DISEASE

By:

Sri Hardianti C111 08 202 Nor Anisah bt Abu Hanipah C111 08 780

Muhammad Fadzhil Bin Amran C 111 09 841Izzad bin Azlan C111 08 793

ReynaldoMailoa C111 09 131Aditya Wisnu Pratama C111 09 296

Advisors:

dr. Jecky C.dr. Rico A.

dr. Sebastian M.

dr. M. Horeb

Department of Orthopaedic & Traumatology

Faculty of Medicine

Hasanuddin University

Makassar

2014



TEXTBOOK

I) DEFINITION

Infantile tibia vara, first described by Erlacher in 1922, is best known as Blount'sdisease after the classic description by Blount in 1937. Blount characterized the

deformity as an abrupt angulation just below the proximal physis, an irregular physeal

line, and a wedge- shaped epiphysis with a “beak” at the medial metaphysis. Apparent

lateral subluxation of the proximal end of the tibia is often present.

II) ETIOLOGY

Several authors have reported a familial occurrence of the conditionand one

report of infantile tibia vara in a family suggested that the disease may be inherited as

an autosomal dominant condition with variable penetrance.However, as noted by

Langenskiöld and Riska, because the radiographic features of infantile tibia vara have

never been seen in patients younger than 1 year and rarely in patients younger than 2

years, the condition is considered a developmental disorder and not a congenital one.

Other studies have found no evidence of an inherited condition and have concluded

that the etiology is multifactorial.

III) ANATOMY

The tibia and fibula are the bones of the leg. The tibia articulates with the condyles

of the femur superiorly and the talus inferiorly and in doing so transmits the body's

weight. The fibula mainly functions as an attachment for muscles, but it is also

important for the stability of the ankle joint. The shafts (bodies) of the tibia and fibula

are connected by a dense interosseous membrane composed of strong oblique fibers.



aspect of the talus. Below and behind the articular facet is a depression called the

malleolar fossa. (3,4)

Picture 1: Anatomy of tibia and fibula. (5)

The anterior compartment, or dorsiflexor (extensor) compartment, is locatedanterior to the interosseous membrane, between the lateral surface of the tibial shaft

and the medial surface of the fibular shaft, and anterior to the intermuscular septum

that connects them. The anterior compartment is bounded anteriorly by the deep fascia

of the leg and skin. The deep fascia of the leg overlying the anterior compartment is

dense superiorly, providing part of the proximal attachment of the muscle immediately

deep to it. The four muscles in the anterior compartment are the tibialis anterior,

extensor digitorum longus, extensor hallucis longus, and fibularis tertius. These

muscles pass and insert anterior to the transversely oriented axis of the ankle joint and,

therefore, are dorsiflexors of the ankle joint, elevating the forefoot and depressing the

heel. The long extensors also pass along and attach to the dorsal aspect of the digits

and are thus extensors of the toes. (4)



The lateral compartment is the smallest (narrowest) of the leg

compartments, bounded by the lateral surface of the fibula, the anterior and

posterior intermuscular septa, and the deep fascia of the leg. The lateral

compartment contains the fibularis (peroneus) longus and brevis muscles. (4)

Picture 2: Muscles of the cruris. (5)

The posterior compartment (plantar flexor compartment, is the largest of

the three leg compartments. The posterior compartment and the calf muscles

within it are divided into superficial and deep subcompartments/muscle groups

by the transverse intermuscular septum. The tibial nerve and posterior tibial and

fibular vessels supply both parts of the posterior compartment but run in the

deep subcompartment deep (anterior) to the transverse intermuscular septum.

Muscles of the posterior compartment produce plantarflexion at the ankle,

inversion at the subtalar and transverse tarsal joints and flexion of the toes. The

superficial group of calf muscles are the gastrocnemius, soleus, and plantaris.



Thus, the muscles of the posterior compartment of the leg are popliteus, flexor

digitorum longus, flexor hallucis longus, and tibialis posterior. (4)

Picture 3: Muscles of the cruris. (5)

IV) PATHOPHYSIOLOGY

There are three types of tibia varum based on the age it begins:

– infantile (less than three years old),

– juvenile (occurs between four and 10 years), and

– adolescent (11 years of age and older).

Physiologic tibia varum occurs between the ages of 15 months to three years.There's no need for treatment for this normal stage of development. But it's not always

clear at this age if the tibia varum is physiologic (normal variation)

or pathologic (Blount's disease).



The general findings have included (1) islands of densely packed cartilage cells

displaying greater hypertrophy than expected from their position in the growth plate,

(2) islands of nearly acellular fibrocartilage, and (3) exceptionally large clusters of

capillary vessels.

The physeal cell columns become irregular and disordered in arrangement and

normal endochondral ossification is disrupted, both in the medial aspect of the

metaphysis and in the corresponding part of the physis.

The varus deformity progresses as long as ossification is defective and growth

continues laterally. In later stages of the deformity, an actual bony bridge may tether

medial growth, and the medial tibial plateau may appear to be deficient

posteromedially.

However, actual depression of the posteromedial tibial articular surface is

probably not present, at least at the outset of the deformity. The “deficiency” is

probably unossified abnormal fibrocartilage whose delay in ossification produces the

appearance of a defect and is directly related to the underlying histopathology.Ligamentous laxity on the lateral side of the knee frequently develops in a neglected

or recurrent deformity.

V) RADIOLOGIC FINDING

Radiography is central to establishing the diagnosis of infantile tibia vara. A

standing anteroposterior view of the lower extremities from hip to ankle should be

obtained. The diagnosis is based on familiar radiographic changes in the proximal end

of the tibia: (1) a sharp varus angulation in the metaphysis, (2) a widened and irregular

physeal line medially, (3) a medially sloped and irregularly ossified epiphysis, and (4)

prominent beaking of the medial metaphysis with lucent cartilage islands within the

beak.

Unequivocal radiographic changes diagnostic of infantile tibia vara are rarely

observed before 18 months of age (the youngest published case wasradiographically



diagnosed at 17 months of age). However, a normal knee radiograph in a toddler does

not rule out infantile tibia vara. As an aid to early identification of toddlers who are at

risk for the development of infantile tibia vara but who have no physeal or

metaphyseal changes, Levine and Drennan measured the tibial metaphyseal –

diaphyseal angle (MDA), the angle created by the intersection of a line connecting the

most promi nent medial portion of the proximal tibial metaphysis (the “beak”) and the

most prominent lateral point of the metaphysis with a line drawn perpendicular to the

long axis of the tibial diaphysis .

VI) CLASSIFICATION

In 1952, Langenskiöld classified infantile tibia vara according to the degree of

metaphyseal – epiphyseal changes seen on radiographs, with six stages varying with

advancing age. General prognostic guidelines were also provided. Restoration to

normal was common in stages I and II disease and possible in stages III and IV

disease, whereas stages V and VI disease were associated with recurrence and

permanent sequelae after treatment by mechanical realignment (osteotomy).

Although Langenskiöld's classification was primarily intended to be aradiographic description of infantile tibia vara, prognostic implications have gradually

been derived from later studie. In 1964, Langenskiöld and Riska reported that a simple

osteotomy could cure the deformity in patients 8 years old or younger.In the few cases

in which simple osteotomy failed, inadequate surgical correction was implicated.

Radiographic stage progression of the deformity was thought to be a consequence of

skeletal maturation rather than an indication of progressive inhibition of medial



physeal growth and worsening of the condition. The premise that 8 years is the critical

age up to which the condition is surgically curable has undoubtedly resulted in a

certain complacency in treating young children, particularly those with demonstrable

stage progression. A number of investigators have reported difficulty applying the

Langenskiöld classification to predict outcome in their own patients.

1. Infantile Blount’s Disease

• Abnormal tibia vara

• More common and usually affects both extremities

• Classic presentation is in a child who is overweight and who begins walking

before 1 year of age; disease is associated with internal tibial torsion.

2. Adolescent Blount’s Disease

• Less severe than infantile forms and more often unilateral

• The epiphysis appears relatively normal and does not have the beaking seen in

infantile forms.



• The most characteristic radiographic finding is widening of the proximal

medial physeal plate.

VI) CLINICAL MANIFESTATION

Genu varum (bowed legs) normal in children less than 2 years old. Blount’s

disease (tibia varum) is best divided into two distinct entities: invantile (0-4 years of

age) and adolescent (over 10 years of age). Infantile Blount’s disease: more common

and usually affects both of extremities. It occurs more often in the overweight child

who begins walking at less than 1 year of age and is associated with internal tibialtorsion. Adolescent Blount’s disease: less severe and more often unilateral. The child

walks with an outward thrust of the knee; in the worst cases there may be lateral



subluxation of the tibia.



VII) TREATMENT

Untreated infantile tibia vara generally results in a nonresolving and sometimes

progressive varus deformity that produces joint deformity and growth retardation,

which can then be corrected only with complex surgical procedures. Even when suchsurgery is performed, substantial articular disruption of both compartments of the knee

may have already occurred.Thus, once the radiographic diagnosis of infantile tibia

vara is certain, the orthopaedist should recommend treatment immediately because

patients treated in the early stages of the disease have a better prognosis. There is no

justification for simply observing a patient with an unequivocal diagnosis. Treatment



choices and prognosis depend greatly on the age of the patient at the time of diagnosis,

which should be the same age at which treatment is recommended.

Orthoses.

If the child is younger than 3 years of age and the lesion is no greater than

Langenskiöld stage II, orthotic treatment is recommended because 50% or more of

these patients can be successfully treated with braces, especially if they have only

unilateral involvement. There may be an inclination to brace patients before a true

Blount lesion is visible on radiographs, particularly when the MDA is suggestive of

varus progression. Thus, when evaluating the reported good outcomes from bracetreatment, one must realize that some patients probably had physiologic genu varum

rather than true infantile tibia vara. Nevertheless, orthotic treatment appears to affect

the natural history favorably The type of orthosis prescribed and the length of time

that the orthosis is worn during a 24-hour period vary. Raney and associates used a

knee-ankle-foot orthosis (KAFO) that produced a valgus force by three-point pressure

in 60 tibiae (38 patients), with lesions in 54 tibiae (90%) resolving without surgery.Significant risks for failure included ligamentous instability, patient weight above the

90th percentile, and late initiation of bracing. Of the 54 tibial lesions that resolved, 27

were treated by full-time orthotic use, 23 by nighttime use only, and 4 by daytime use.

Three of the six tibiae requiring surgery had been treated with full-time orthotic use

and three with nighttime use only. Based on these findings, the authors conjectured

that nighttime-only bracing might be as efficacious as full-time bracing, although theyacknowledged that inherently one would expect daytime use (i.e., during weight

bearing) to be the most important factor in successful orthotic treatment. On the other

hand, Zionts and Shean reported daytime ambulatory bracing to be successful in

altering the natural history of tibia vara in patients younger than 3 years with

Langenskiöld stage I or II disease.



We have used conventional KAFOs, conventional hip-knee-ankle-foot orthoses

(HKAFOs), and elastic KAFOs in the treatment of infantile Blount's disease. Since

1987, the elastic Blount brace, a medial upright design that uses a wide elastic band

just distal to the knee joint, has been used almost exclusively because of its ease of

fabrication and smaller profile. With this orthosis, 65% of tibiae had successful

outcomes at an average follow-up of 5.9 years. However, corrective osteotomies for

one or both extremities were eventually required in 70% of patients with bilateral

involvement, as opposed to only 6% of patients with unilateral involvement. All of the

patients were instructed to use the brace during the day (i.e., during weight bearing).

Depending on the patient's physician, some patients were encouraged to use the brace

for 20 to 24 hours per day.

Treatment of Langenskiöld Stage II Lesions.

Surgical treatment in the early stages of the disease (stage II) is crucial to

achieve permanent and lasting correction and to avoid the sequelae of joint

incongruity, limb shortening, and persistent angulation. Patients with stage I or II

disease have a significantly lower incidence of repeat osteotomy than do those with



stage III disease.Surgical overcorrection of the mechanical axis to at least 5 degrees of

valgus by 4 years of age, along with lateral translation of the distal osteotomy

fragment, is believed to be optimal. Such overcorrection ensures that the supine

correction attained at surgery will be sufficient to translate the mechanical axis into the

lateral compartment of the knee once the patient begins bearing weight.

Overcorrection of the mechanical axis offsets the tendency of the knee to go back into

varus as a result of any sloping of the medial epiphyseal surface and relaxation of the

lateral ligaments.

Although Schoenecker and colleagues reported that correction to within 5

degrees of neutral alignment would prove adequate, most authors recommend

physiologic valgus or overcorrection. Based on the physeal inhibition phenomenon

proposed by Cook and associates, overcorrection to absolute valgus alignment is

required to reverse the excessive compressive forces medially and allow a

Langenskiöld II or III physis not already irreversibly damaged to respond to such

mechanical unloading.

Treatment of Langenskiöld Stage III Lesions.

Stage III lesions can respond to corrective osteotomy alone in patients older than 4

years. However, the longer the delay in surgery after 4 years of age, the greater the

risk for recurrence, which is not uncommon with stage III lesions. Thus, because of

the worsening prognosis, neither observation nor orthotic treatment is recommended

beyond this age, especially if the deformity exceeds 10 degrees of femorotibial varus.

Treatment of Langenskiöld Stages IV/V Lesions.

Lesions greater than stage III cannot be definitively corrected by simple mechanical

realignment because physiologic physeal arrest has already occurred by stage IV.Even

though no bony bridge can be visualized by tomographic methods in stage IV or V



lesions, physeal damage has progressed to the point where stages IV and V lesions

effectively act as medial physeal arrests.

Treatment of Langenskiöld Stage VI Lesions.

Treatment of stage VI lesions with established bony bridges must also be

individualized. Factors to be considered are patient age, the amount of skeletal growth

remaining, and the degree of deformity of the joint surface. If the patient has less than2 years of growth remaining and a relatively normal joint surface, corrective

osteotomy with complete physeal closure is a practical means of obtaining and

maintaining correction. The osteotomy can performed through the physis so that the

mechanical correction is placed as close to the joint as possible and permanent physeal

closure occurs.

blount's disease (textbook)

Documents