Blounts disease

blounts disease by dr. mayur jejurikar

1. Welcome to short note discussion Presented by: Dr. Mayur .R. Jejurikar Resident, Phase – B, Dept. of Orthopaedic Surgery, BSMMU.

2. Topic of discussion: Tibia vara Osteochondrosis deformans tibiae Erlacher’s disease BLOUNT’S DISEASE Synonyms:

3. Historical background: Erlacher is credited with the first description of tibia vara & internal tibial torsion in 1922. But, it was Walter Blount’s article in 1937, that prompted recognition of this disorder. Later in 1952, Langenskiold described radiographic changes & stages of the disease in the Scandinavian population.

4. Introduction: Tibia vara/ Blount’s disease is a developmental condition. It is characterised by a disturbance of enchondral ossification at the upper end of tibia, affecting the medial portion of the growth plate, mainly in its posteromedial aspect & the medial portion of the epiphyseal ossification center. As a result, an abrupt varus angulation develops at the proximal portion of the metaphysis while the diaphysis remains straight.

5. Introduction: Secondary effects include internal torsion of the tibia, insufficient ossification of the medial portion of the medial tibial condyle & stretched lateral collateral ligament. Blount described tibia vara as “an osteochondrosis similar to coxa plana & Madelung deformity but located at the medial side of the proximal tibial epiphysis”.

6. Relevant anatomy:

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11. Etiology: The exact cause is unknown & the condition is idiopathic. Enchondral ossification seems to be altered. Suggested causative factors include infection, trauma, osteonecrosis & a latent form of rickets, although none of these have been proved. A combination of hereditary & developmental factors is most likely cause. Weight bearing must be necessary for its development bcoz it doesn’t occur in non-ambulatory patients. Relationship of early walking & obesity with Blount's disease has been clearly documented. Neither sex seems predisposed. Children of negroid descent, particularly in the West Indies & in West Africa, appear to be affected more frequently than the others.

12. Pathology: The cartilage over the medial side of the epiphyseal growth plate, particularly in the area of the ‘beak’, is grossly disorganized. As a result of disordered endochondral ossification, the medial portion of the ossification zone of the metaphysis forms a step-like unossified defect within which there are intermingled islands of bone and abnormal cartilage. The osteocartilagenous tissue extends medially from the metaphysis as an outgrowth about a bony beak. The intra-articular pathology consists of: enlargement & hypermobility of the medial meniscus, depression of the anterior aspect of the medial femoral condyle & d epression of the posteromedial plateau of the tibia.

13. Types of tibia vara: According to the age, Blount described two types of tibia vara: Infantile : begins before 8 years of age Adolescent : begins after 8 years of age but before skeletal maturity. Further subdivided into: 1) occurring between 8 & 13 years caused by partial closure of the physis after trauma or infection. 2) occurring between 8 & 13 years in black & obese children without a distinct cause.

14. Clinical presentation: INFANTILE TYPE It is bilateral & symmetrical in approximately 60% of affected children . The bowleg deformity becomes apparent when the infant starts to stand & walk. It is impossible to differentiate it from the physiological bowing before 2 years of age. Later as the age increases the deformity worsens which is not the case with physiological bowing. The components of the deformity include a sharp medial angulation of the tibia at the metaphysis, more evident in the weight-bearing position.

15. Contd: Internal tibial torsion & pes planovalgus develop secondarily. In compensation there is hypertrophy of the medial femoral condyle. A bony, hard, non-tender prominence is palpable on the medial epiphysiometaphyseal junction. SIFFERT KATZ sign : As the extended knee is slightly flexed, the medial femoral condyle loosely engages the depression in the medial tibial plateau & posteromedial rocking is demonstrable. The deformity worsens progressively & an increasingly sharp, usually bilateral, bowleg angulation & waddling gait become pronounced.

16. Contd: In long standing cases, there is slight flexion deformity & the collateral ligaments become lax & joint becomes unstable. Limb length discrepancy is usually not seen as it is bilateral.

17. CONTD: ADOLESCENT TYPE Not as common as infantile type. Develops between 8-13 years of age. The deformity is unilateral, is generally mild to moderate, rarely exceeds 20 degrees. It is never associated with a medial osteocartilagenous prominence. Secondary internal tibial torsion & pes planovalgus do not develop. The leg shortening may be appreciable. The patient is usually obese.

18. Radiography: X-ray is the most commonly done investigation for the diagnosis. Characteristically the medial half of the epiphysis appears short, thin & wedged. Physis is irregular in contour & slopes medially. The medial portion of the metaphysis displays a beak-like projection extending medially & surrounded by multiple radiolucent areas (cartilage).

19. Contd: This projection present medially is often palpable, but this projection is not diagnostic of tibia vara. Medial metaphyseal fragmentation is pathognomic for the development of a progressive tibia vara. The angular deformity occurs just distal to this projection.

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21. Contd: Langenskiold noted progression of epiphyseal changes & the deformity through six stages with growth & development. At stage VI, the medial portion of the epiphysis fuses at a 90 degree downward angle.

22. Contd: Various angles of the femur & tibia at the knee can be determined on the radiographs, when the deformity is present.

23. contd: Normally, tibiofemoral angle progresses from pronounced varus before the age of 1 year to valgus between ages 1.5 & 3 years. Several authors have suggested that deviation from normal tibiofemoral angle development indicates Blount disease, & the metaphyseal-diaphyseal angle is an early indicator of Blount's disease. This measurement is not an absolute prognosticator of Blount’s disease, but a metaphyseal-diaphyseal angle of > 11 degrees warrants close observation.

24. Contd: Most authors agree that mechanical axis of the limb, as it relates to the tibiofemoral angle on the radiographs, should be the most functional measurement of the amount of deformity present. The intra-articular pathology is defined by double-contrast arthrography & by arthroscopy. These will delineate the defects of the articular surfaces as well as the state of the medial meniscus.

25. Histological findings: In the infantile type, bone changes include delayed ossification of the medial epiphysis & metaphysis of the proximal tibia. These changes include cell hypertrophy & dense cellularity, fibrocartilage islands & abnormally large group of capillaries.

26. Differential diagnosis: Congenital bowing of the tibia. Vitamin-D resistant rickets. Deformity of the medial tibial condyle due to gonadal dysgenesis.

27. Treatment: Depends upon the age of the child & severity of the varus deformity. Non-operative treatment: Generally, observation or a trial of bracing is indicated for children between ages 2-5 years. Ambulatory bracing with an above-the-knee orthosis is effective. If the disease continues to progress with brace treatment, it will no longer be effective.

28. Contd: Operative treatment: P rogressive deformity usually requires osteotomy. Recurrence of the deformity is not as frequent after osteotomy at an early age as after osteotomy when the child is older, with recurrence rates of about 80% reported in older children compared with less than 20% in younger children. One cause of recurrence after osteotomy is a physeal bar. Greene listed the following criteria for determining tomographically whether bony bar is present or not preoperatively: Age > 5 years. Medial physeal slope of 50-70 degrees. Langenskiold grade IV radiographic changes. Body wt. > 95 th percentile. Black girls who meet the previous criteria.

29. Operative guidelines: In children above the age of 9 years with more severe involvement, osteotomy alone, with bony bar resection, or with epiphysiodesis of the lateral tibial & fibular physes may be indicated. Medial physeal bar resection alone has been reported to be effective when premature closure of the physes is evident, but significant angular deformity would not be corrected by bar resection alone. Lateral tibial epiphysiodesis can be done, with/without osteotomy, after the age of 9 years but before skeletal maturity. In unilateral involvement, epiphysiodesis of the uninvolved leg may be indicated to correct leg-length discrepancy. For older patients in whom bracing & tibial osteotomy have failed, & when the risk of abnormal spontaneous medial epiphysiodesis is high, intraepiphyseal osteotomy & valgus metaphyseal osteotomy to correct severe joint instability & varus angulation respectively may be indicated. The Ilizarov technique is effective for correction of deformity & lengthening if needed in an adolescent patients.

30. Osteotomies: Metaphyseal / oblique osteotomy by Rab technique:

31. Contd: Opening-closing Chevron osteotomy by Greene technique. Modification of dome osteotomy.

32. Contd: Epiphyseal & M etaphyseal osteotomy by Ingram, Canale & Beaty technique.

33. Contd: Intraepiphyseal osteotomy by Siffert, Storen & Johnson technique

34. Contd: Hemielevation of the epiphysis osteotomy with leg lengthening using an Ilizarov frame by Jones & Hefney technique

35. Contd: Hemicondylar tibial osteotomy by Zayer technique

36. Contd: External fixation , including the Taylor spatial frame, may be indicated to achieve stability after osteotomy & immediate correction & seems to be an excellent method of treating an extremely obese pt. for whom unilateral or bilateral casting is impractical.

37. Complications of high tibial osteotomy: Neurovascular complications after an osteotomy result most commonly from vascular occlusion or common peroneal nerve palsy. Stretching of the anterior tibial artery occurs at the interosseous membrane with varus correction (as for genu valgum), & compression of the artery occurs with valgus correction (as for genu varum). Decrease in dorsiflexion & severe pain on plantar flexion of the toes are the most common clinical signs of occlusion of the artery or of an anterior compartment syndrome. Matsen & Staheli outlined the appropriate management for each of them.

38. Follow-up: Follow-up & post-operative weight bearing is specific to the procedure performed. In general, osteotomies heal in approximately 6-8 weeks. In general, external fixation remains in place for 12 weeks postoperatively. Continuing follow-up care after initial surgical correction is necessary because of the risk of recurrence.

39. Outcome & prognosis: The prognosis in the infantile form of Blount disease must be considered separately from that in the adolescent form .  Infantile tibia vara has a good prognosis , and recurrence rates of deformity are low when treated at a young age and early stage .  In the late-onset form of the disease, regression does not occur and the varus deformity may worsen over time.