blounts disease.pptx

orthopedics journal ckub current review

1. Introduction :- Blount disease is a developmental condition characterized by disordered endochondral ossification of the medial part of the proximal tibial physis resulting in multiplanar deformities of the lower limb. Progressive pathologic genu varum centered at the tibia commonly seen in children 2 to 5 years of age Diagnosis is suspected clinically with presence of a genu varum/flexion/internal rotation deformity and confirmed radiographically with an increased metaphyseal-diaphyseal angle. Risk factors overweight children, early walkers (< 1 year) & Hispanic and African Americans. Obesity can substantially increase the compressive forces generated on the medial compartment of the knee joint in a child leading to genu varum ,(As per Heuter’s Volkmann law.)

2. Secondary to the asymmetrical growth with relative inhibition of the posteromedial portion of the proximal tibial growth plate, a three-dimensional deformity of the tibia occurs, viz – - Procurvatum (apex anterior), -Internal rotation, -Possible limb shortening in unilateral cases. This entity can lead to a progressive deformity with gait deviations, limb-length discrepancy, and premature arthritis of the knee.

3. Classification Based on age of onset:- Early-onset(Also called infantile type , onset at before 4 years) Juvenile type (onset at the age of 4 - 10 years) and Adolescent type (onset after the age of 10 years). Etiology and Pathogenesis A linear relationship between the magnitude of obesity and biplanar radiographic deformities in children with the early-onset form of Blount disease and in patients with a body-mass index of >40 kg/m2 irrespective of the age at the onset of the Blount disease. Despite having a lower body-mass index, children with early-onset Blount disease had more severe varus and procurvatum deformities of the proximal part of the tibia. Increased pliability of the unossified epiphyses of younger patients causing more growth inhibition than occurs in adolescents

4. An obese child with large thighs has difficulty adducting the hips adequately and this may result in ‘‘fat-thigh gait’’ by producing a varus moment on the knees. Childhood obesity reduces bone mineral content to levels below what would be predicted on the basis of body weight. Despite being referred to as tibia vara , Blount disease may involve other sources of medial axis deviation arising from the distal part of the femur and an intra-articular deformity creating dynamic varus malalignment. This is more commonly seen adolescents with late-onset disease . Other factors linked with obesity like sleep apnea syndrome,have also been implicated.

5. A full-length radiograph allows detailed assessment of the mechanical axis deviation and joint orientation angles, which are crucial for determining the site(s) of deformity correction. Medial epiphysis is short, thin & wedged. Medial metaphyseal projection ( beaking ),often palpable. Physeal contour is irregular, slopes medially. Asymmetric bowing in bilateral cases

6. Stage 1 - Medial metaphyseal beaking . Stage II - Saucer-shaped defect of medial metaphysis Stage III -Saucer deepens into step Stage IV- Sloping of epiphysis over medial beak Stage V - Double epiphysis Stage VI - Medial physeal bony bar Progressive radiographic changes seen in early-onset Blount disease Langeskiold radiological staging

7. Radiographs and Imaging

8. Radiographic Indices seen for knee joiont The mechanical tibiofemoral angle - Angle between [A line drawn from the center of the hip to the center of the knee] and [A line drawn from the center of the knee to the center of the ankle .] The metaphyseal -diaphyseal angle of Drennan - A ngle between [A line drawn through the most distal aspects of the medial and lateral beaks of the proximal tibial metaphysis ] & [A line perpendicular to a line drawn along the lateral aspect of the tibial diaphysis .] <10 = Will mostly undergo natural resolution 11- 16 = Needs a observation >16 = Most cases will land up in blounts diease

9. Lateral Distal Femoral Angle (LDFA) is defined by the angle between the femoral mechanical axis and the articular surface of the distal femur Medial Proximal Tibia Angle (MPTA) is defined by the angle between the tibial mechanical axis and the articular surface of the proximal tibia.

10. The percentage deformity of the tibia, % DT is calculated as the degree of tibial varus divided by the total amount of limb varus (femoral varus [FV] + tibial varus [TV]) ( Tibial varus is the medial angle between the mechanical axis of the tibia and a line drawn parallel to the distal femoral condyles ) ( Femoral varus is represented by the medial angle between the mechanical axis of the femur and a line parallel to the distal femoral condyles .)

11. Management options Treatment is customized for each patient on the basis of a variety of factors, including the child’s age, the magnitude of the deformity, the limb-length discrepancy, psychosocial factors, and the surgeon’s training and experience . For infantile type we can go for both bracing (as in many cases of infantile type can undergo a spontaneous resolution)and surgery, while only surgical options are considered for adolescent Blounts . Management options include – Observation with repeat clinical and radiographic examinations Use of long leg orthoses Realignment osteotomy Lateral hemiepiphyseodesis , Gradual asymmetrical proximal tibial physeal distraction Resection of a physeal bar, and elevation of the medial tibial plateau.

12. Orthroses Because of high rate of spontaneous correction, in Langeskiold I or II stage or infantile patients with age of <3 years, brace treatment can be tried. Brace which is advised is the KAFO brace which allows to control instabilities in the lower limb by maintaining alignment and controlling motion.

13. External Fixation with Gradual Correction Gradual correction with distraction osteogenesis appears to be a safe and reliable means of treating multiplanar deformities, including limb-length discrepancy. The reported prevalences of neurovascular injury, compartment syndrome, and loss of correction , have been substantially lower than following acute deformity correction in Blount disease. With the introduction of the Taylor Spatial Frame and the ability to perform six axis deformity correction on the basis of a computer-generated schedule,correction is possible for multiplanar deformities with greater accuracy.

14. The patient underwent gradual correction with distraction osteogenesis at the proximal part of the tibia

15. Proximal Tibial Metaphyseal Osteotomy A variety of techniques have been advocated, including closing wedge, opening wedge, dome, serrated, and oblique osteotomies,chevron osteotomy . Furthermore, different fixation methods have been reported, including cast immobilization, smooth pins and wires, inter-fragmentary screws, plates and screws and external fixators .

16. Hemiepiphyseodesis (growth modulation) The authors recommended hemiepiphyseal stapling in children younger than ten years old in whom the preoperative mechanical axis of the lower extremity is within the medial half of the medial compartment. Done to allow growth in media physis to ‘catch up’ & thereby correcting the deformity.May be of 2 types :- Temporary – using bone staples. - May recure after removal, - High rate of failure in obese. B) Permanent

17. Elevation of the Medial Plateau In the advanced stages of early-onset Blount disease, the tibia can translate laterally with the medial femoral condyle falling into the posteromedial depression. Elevation with internal fixation can be done by use of a structural allograft. It is recommended for the few children older than six years of age who have severe early-onset Blount disease ( Langenskiold stage V or VI).

18. Physeal Bar Resection Resection of a physeal bar at the medial aspect of the proximal part of the tibia with interposition of fat or silicone and a simultaneous valgus osteotomy is done. Used for treatment of moderate-to-advanced early-onset Blount disease (a Langenskiold stage of > III) Complications Compartment syndrome Recurrence Chronic joint pain Vascular occlusion Peroneal palsy Refracture