Tibia Vara is a developmental disorder characterized by disturbance of the orderly sequence of endochondral ossification of the upper end of the tibia, affecting a medial portion of the growth plate mainly in posteromedial aspects and the medial portion of the epiphysial ossification center.
(BLOUNT’S DISEASE, OSTEOCHONDROSIS DEFORMANS TIBIA,ERLACHER DISEASE)
Blount’s disease occurs due to insufficient ossification of the medial portion of the medial tibial condyle which leads to abrupt varus angulation developing at the proximal portion of metaphysis but diaphysis remains straight.
It also stretches lateral ligaments
Secondary effects of tibia vara include internal torsion of the tibia
Itretards longitudinal growth, so there is depression at the medial condyle which later develops early medial compartmental Osteoarthritis
Etiology
Idiopathic
Clinical Findings of tibia vara
Bowleg deformity ( become apparent after infants begin to walk)
Initially, in the infantile period, parents are not able to differentiate between physiological or pathological bowing but with time, deformity worsens rather correction
So there will be ↑ deformity, which leads to ↑ a load of the medial plateau and it further inhibits endochondral ossification (cycle continues)
Components of deformities of Blount’s disease
- Sharp medial angulation of tibia at the metaphysis
- Internal tibial torsion
- Pes-planus valgus
- Medial condyle hypertrophies
Collateral ligaments become lax and joints become unstable.
Shortening but not appreciable
The characteristic feature of Blount’s disease is the Siffert Katz Sign which is explained below.
Siffert-Katz Sign:
The disease process initially affects posteromedial aspects of the medial tibial condyle
↓
Ossification center develops poorly
↓
Cartilage shows the earliest sign of depression
↓
Dip deformity- seen in double contrast radiograph
↓ In the full extension of the knee (taut collaterals) where the anterior portion of the femur and tibia are firmly opposed
In knee flexed (10°-20°), the medial femoral condyle loosely engaged the depression in the medial tibial plateau and sub-luxed posteromedially ( joint unstable before lateral ligaments stretch)
This sign the patient demonstrate is called the Siffert Katz Sign.
In the untreated children, deformities worsen progressively and an increasingly sharp, usually bilateral, bow leg angulation and waddling gait.
Adolescent type Blount’s disease:
Irregular, narrow, and sometimes prematurely obliterated
- Seen in an obese child
- 8-13 years
- Unilateral
- Minimal to moderate varus < 20°
- Cause of progressive LLD
Treatment of Adolescent Blount’s disease
Osteotomy is not done till skeletal maturity, before osteotomy premature closure of a medial portion of the growth plate is identified earliest (CT) and epiphysiodesis of the lateral part of the growth plate and the upper end of the fibula is done.
Radiological findings:
In Infantile type
- Short angular deformity below upper tibial epiphysis
- The medial side epiphysis plate is widened, irregular (Step like deformity)
- Surrounded by multiple radiolucent areas (cartilage)
Intraarticular pathology is diagnosed by arthroscopy / double-contrast arthrogram which delineates the defect of articular cartilage surface/meniscus
Differential diagnosis of Blount’s disease
- Congenital bowing of the tibia
- Vitamin-D resistant rickets
- Gonadal dysgenesis
Classification of Tibia Vara
Langenskiold’s classification is used to classify tibia vara as per severity.
| Stages | Age group (years) | Features |
|---|---|---|
| Stage 1 | 2-3 | Medial metaphyseal beaking |
| Stage 2 | 2.5-4 | Saucer shape defect in the medial metaphysis |
| Stage 3 | 4-6 | Saucer deepens into steps |
| Stage 4 | 5-10 | Sloping of epiphysis over medial beak |
| Stage 5 | 9-11 | Double epiphysis |
| Stage 6 | 6-13 | Medial physis bone bar |
Treatment Options for Tibia Vara
For mild deformity, a short period of observation is commenced
Orthosis will ↓ compression loading in the medial portion of the upper tibia which may be effective
Early Age, deformity < 30, < 4 years:-
Sufficient correction by osteotomy yields a permanent cure
Child >8 years or more or inadequate correction may lead to reoperations.
Types of osteotomies for Tibia Vara
- Curved osteotomy of the tibia with oblique osteotomy of the fibula at a distance from the peroneal nerve ( early age, deformity <10)
- Curved osteotomy of the tibia with oblique osteotomy of fibula and epiphysiodesis of the lateral portion of the tibial growth plate and the upper end of the fibula ( after 9 years and before skeletal growth)
- Osteotomy and elevation of medial tibial condyle and epiphysiodesis of the lateral portion of the tibial growth plate. ( indicated in extreme ligamentous laxity)
- Medial open wedge osteotomy distal to the level of the tibial tubercle (if LLD is a problem)
Physioplasty
- Sufficient residual growth potential
- Limited amount of peripheral bone bridge
Surgical excision of the bone bridge and its overlying periosteum until deep with in periphery of cartilage is exposed. Proper hemostasis is done which is filled with autologous fat transplant into the cavity. This method helps to restore the longitudinal growth restores and deformity spontaneously corrects.
