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Blounts Disease
1. What are the characteristics of Physiologic Genu Varum?
Physiologic genu varum has three characteristics
Deformity less than 10° of varus
Normal physis on radiographs
Medial bowing of both tibia and femur
2. What is the normal progression of physiologic angular variations in a child
Maximum genu varum - 6 -12 months
Neutral alignment – 18 – 24 months
Maximum genu valgum – 4 years
Gradually shift to normal alignment – by 11 years
3. When will you call genu varum abnormal?
Presence of genu varum after 2 years of age is abnormal.
4. How will you differentiate apparent and pathological genu varum?
In apparent genu varum the deformity will correct when hip and knee are made straight with patella facing forward. This is mostly an internal torsion deformity.
5. What are the indications for x rays in tibia vara?
- Child more than 3 years of age
- Asymmetric or unilateral deformity
- Site of deformity is in proximal tibia
- Other features of possible pathological etiology like short stature, enlarged swollen epiphyseal area, trauma, infection, short tibia and fibula.
5. Define tibia Vara?
Growth retardation at the medial aspect of proximal tibia epiphysis and physis usually resulting in progressive bow leg.
6. What are radiographic characteristics of Blount’s disease [Infantile tibia vara]?
- there are 4 characteristics
-abrupt angulation just below proximal physis
irregular physeal line
wedge shaped epiphysis
beak like medial metaphysis with apparent lateral Subluxation of proximal tibia.
7. What is the first radiographic sign of Blount disease? Or what radiographic features help in early diagnosis of Blount disease?
- First sign of Blount’s disease is development of radiolucency and fragmentation in medial part of proximal tibia metaphysis
8. Describe Langenskoiid stages of Blount’s Disease?
I and II – radiolucency and fragmentation in medial part of proximal tibia metaphysis and gradual wedging of bony epiphysis
III – Appearance of a shelf in the metaphysis. This metaphyseal depression is filled with cartilage which is supported by bony metaphyseal beak. Epiphysis becomes more wedged medially and medial epiphysis narrows. Fibula overgrowth
IV – metaphyseal shelf increases in depth and is filled with bone. Increased angle between medial and lateral physis of tibia [if angle >60°, recurrence is likely after surgery]
V – Metaphyseal shelf fills more and a radiolucent line appears medially and inferiorly giving appearance of double physis
VI – both arms of growth plate ossify
9. How will you differentiate Blount disease from physiological varus?
Two characteristics help
- patient is generally obese
-there is lateral thrust and limp
10. What is the main differentiating radiographic picture between achondroplasia and Blount’s disease?
- Fibular overgrowth is seen in Blount’s, but not in achondroplasia.
11. what is the treatment protocol for Blounts disease?
All cases of blounts diease require treatment without which the deformity will progress.
Conservative treatment by brace and surgical treatment are options available
Age is the most important factor that determines protocol
Age <3 years – conservative bracing
Age 3 – 4 years – depending of stage of disease and response to conservative management. Less than 4 years is the optimal time for correction to avoid sequeale of joint incongruity, limb shortening and persistent angulation
Age >4 years – surgical management
12. Indications for Brace treatment of Blounts Disease?
Upto stage II disease and less than 36 months of age. 50% of patients respond well specially cases with unilateral disease
13. define failure of brace treatment?
If a trial of one year of brace treatment fails to correct the deformity to neutral alignment, the brace treatment is said to have failed and patient will require osteotomy. [this criteria before 4 years of age]
14. What are bad prognostic indicators for brace treatment of Blount’s Disease?
Ligamentous instability, patients weight >90 percentile and late initiation of brace therapy. Also almost 70% of time one of the knees in a bilateral deformity will require corrective osteotomy.
15. what brace to be used for correction of Blount’s Disease?
A Knee-ankle-foot orthosis [KAFO] with a medial upright to produce a valgus force by three point pressure. This brace should be worn 23 hours a day although some studies have reported day time only wear to be successful.
16. When to stop Brace therapy?
In two scenarios the brace therapy is to be stopped.
Success – the valgus correction has to be increased by bending the medial upright every 2 months and when the standing radiographs reach neutral alignment, brace wear can be gradually tapered off.
Failure – as mentioned above
17. Why is over correction advised for Blount’s?
Over correction oatleast 5° of valgus is adviced to reverse the excessive compressive forces medially and to allow the physis to respond to mechanical unloading. This will also prevent the tendency of the knee to go back into Varus due to sloped medial epiphysis and relaxed ligaments.
18. What are principles of osteotomy for Blount’s disease?
Achieving valgus correction is more important than type of osteotomy [open, closed, dome]
Level of osteotomy – distal to patellar tendon to spare the apohysis
External rotation of the distal fragment - to counter the intorsion.
Fibular Osteotomy – in proximal third, through separate incision
Internal fixation – K wires, Plates
Fasciotomy - [optional] - anterior, lateral and posterior compartments
19. How will you manage a stage III lesion?
These require to be managed surgically and delay more than 4 year have chance of recurrence so regular follow up is advised
20. How will you manage stage IV and V Blount’s Disease?
The lesions in these stages are associated with physeal growth arrest. Thus a combination of deformity correction and a physeal procedure is required. Surgery has to be selected depending on age of the patient. In young children [6 to 8 years] – realignment with medial physeal resection and placement of interposition material to prevent rebridging. Also Lateral Epiphyseodesis / or osteotomies and total physeal closure can be done but, this will lead to shortening which will require limb lengthening.
21. How will you treat Stage VI lesion?
<2 years of physeal growth remain – physeal closure and corrective osteotomy
>2 years of physeal growth – medial physeal resection and interposition to prevent rebridging combined with re alignment.
Joint very incongruous – Intra-articular osteotomy
Most patients with stage VI disease will have degenerative disorder later due to intra articular in congruency.
Literature on Blount Disease
1. [Best article Must read ] Blount disease. Sabharwal S. J Bone Joint Surg Am. 2009 Jul;91(7):1758-76.
Two clinically distinct forms of Blount disease (early-onset and late-onset), based on whether the lower-limb deformity develops before or after the age of four years, have been described. Although the etiology of Blount disease may be multifactorial, the strong association with childhood obesity suggests a mechanical basis. A comprehensive analysis of multiplanar deformities in the lower extremity reveals tibial varus, procurvatum, and internal torsion along with limb shortening. Additionally, distal femoral varus is commonly noted in the late-onset form. When a patient has early-onset disease, a realignment tibial osteotomy before the age of four years decreases the risk of recurrent deformity. Gradual correction with distraction osteogenesis is an effective means of achieving an accurate multiplanar correction, especially in patients with late-onset disease.
2. Laville JM, Chau E, Willemen L, Kohler R, Garin C. Blount's disease: classification and treatment. J Pediatr Orthop B. 1999 Jan;8(1):19-25.
forty-three tibia vara in 27 patients were analyzed retrospectively in two centers. The criteria for diagnosis of the child form are discussed. A simple classification is suggested to facilitate the choice of treatment. In stage 0 (possible Blount's disease), the patient is younger than 2 1/2 years, and an observation period is indicated for gathering data. In stage 1 (confirmed Blount's disease and absence of medial metaphyseal bony bridge), known as physis+, a valgization osteotomy is proposed. In stage 2 (evidence of a medial metaphysoepiphyseal bony bridge) known as physis-, valgization osteotomy with lateral epiphysiodesis and treatment of the lower limb discrepancy is proposed. For stages 1 and 2, there are two possibilities: normal medial tibial plateau or sloping of the medial tibial plateau, indicating a transphyseal elevation osteotomy. When one-step correction is proposed for stage 2 disorder, external fixators such as Orthofix or Ilizarov devices are useful.
3. Orthotic treatment of infantile tibia vara. Raney EM, Topoleski TA, Yaghoubian R, Guidera KJ, Marshall JG. J Pediatr Orthop. 1998 Sep-Oct;18(5):670-4
Difficulty differentiating physiologic genu varum from early Blount's disease persists. Drennan's metaphyseal-diaphyseal (MD) angle remains the most consistently valuable radiographic parameter despite measurement error. Clinical risk factors also should be considered. All patients receiving orthoses for genu varum since 1985 were reviewed. The focus of the study was those patients with an MD angle of >16 degrees or between 9 and 16 degrees with a clinical risk factor for progression. Risk factors considered were ligamentous instability, obesity, asymmetry, and being female, black, or Hispanic. Thirty-eight patients with 60 tibiae were included. The success rate was 90%. Risk factors for failure (six cases) were instability, obesity, and delayed bracing. In cases with MD angles >16 degrees, the success rate was 86%. The results of orthotic treatment, restricted to patients meeting the stated parameters, represent improvement on the reported natural history.
4. Long-term results after infantile Blount's disease. Ingvarsson T, Hägglund G, Ramgren B, Jonsson K, Zayer M. J Pediatr Orthop B. 1998 Jul;7(3):226-9.
A long-term follow-up of 49 patients with an average age of 38 years (range: 25-67 years) who had experienced infantile Blount's disease was done. Thirty-seven patients had bilateral disease, giving a total of 86 affected knees. Thirty-eight knees had conservative or no treatment during childhood; 13 were treated by epiphysiodesis, and 35 by osteotomy. At follow-up, 11 knees showed arthrosis, and 9 were graded as mild. Ten knees had been surgically treated by medial meniscectomy at an average age of 29 years (range: 19-45 years), after the diagnosis of Blount's disease. Four of the knees showed arthrosis. Most of the patients had a straight leg and mild or no pain from their knee. It is concluded that most children with infantile Blount's disease will, at the age of 40 years, have a straight leg without arthrosis and that one third can reach this result without any treatment.
5. Effectiveness of brace treatment in early infantile Blount's disease. Richards BS, Katz DE, Sims JB. J Pediatr Orthop. 1998 May-Jun;18(3):374-80.
In an effort to determine whether bracing is effective in reversing early infantile Blount's disease, 27 patients with Langenskiold stage II disease were studied. Ten patients had bilateral disease (two of these patients had stage III disease affecting one side). Age at brace initiation averaged 2.1 years (range, 1.5-3.2). The duration of bracing averaged 9.7 months. Follow-up averaged 5.9 years. Successful outcomes (improved alignment without the need for osteotomy) were achieved in 19 (70%) patients, the majority of them having unilateral disease. Of the 37 affected extremities, 24 (65%) had successful outcomes. Eight patients (13 extremities) required tibial osteotomies and were classified as bracing failures. Of the 10 patients with bilateral involvement, seven (70%) required osteotomies for one or both extremities, whereas only one (6%) of 17 patients with unilateral involvement required osteotomy. Bracing appears to be effective in stage II infantile Blount's disease, particularly in those with unilateral involvement. Children with bilateral disease are most at risk for requiring subsequent corrective osteotomy.
6. Acute versus gradual correction of idiopathic tibia vara in children: a systematic review.
Gilbody J, Thomas G, Ho K. J Pediatr Orthop. 2009 Mar;29(2):110-4.
Idiopathic tibia vara (Blount disease) is an acquired form of tibial deformity found mainly in children who are Afro-Caribbean and obese. It is uncommon. Several methods have been described for the surgical treatment of this condition, which can be categorized as either acute or gradual correction. The aim of this study is to review the evidence comparing the outcome of acute versus gradual correction of childhood tibia vara using accuracy of reduction as the primary outcome measure.
A systematic search was made of the literature across multiple databases to find all studies describing acute or gradual correction of this condition that reported radiographic correction as an outcome measure.
One retrospective comparative series was found that provided weak evidence of an improvement in mechanical axis deviation using gradual correction with a Taylor Spatial Frame compared with acute correction. Seventeen other case series were found, from which, there was no evidence of an advantage for either form of treatment.
There is very little evidence to recommend one form of correction over the other.
LEVEL OF EVIDENCE: Systematic review of case series (level IV).
