• The primary outcome is the variation of the angle of Regional Vertebral Kyphosis or, in the case of asymmetrical fractures, the angle of lateral vertebral inclination between inclusion and one year follow-up examination [ Time Frame: 1 year ] [ Designated as safety issue: Yes ]
  

• Pain evaluation using a visual analogic scale [ Time Frame: J-20 à J-7 / J6 / J45 /J90 /J180 / J360 ] [ Designated as safety issue: Yes ]
  
• EIFEL questionnaire for back pain evaluation [ Time Frame: J-20 à J-7 / J6 / J45 /J90 /J180 / J360 ] [ Designated as safety issue: Yes ]
  
• Quality of life evaluation (SF 12). [ Time Frame: J-20 à J-7 / J6 / J45 /J90 /J180 / J360 ] [ Designated as safety issue: Yes ]
  
• Analgesics intake according to the WHO classification (Classes 1, 2 and 3). [ Time Frame: J-20 à J-7 / J6 / J45 /J90 /J180 / J360 ] [ Designated as safety issue: Yes ]
  
• Regional spine Kyphosis angle and global thoracic and lumbar Kyphosis angle [ Time Frame: J-20 à J-7 / J6 / J45 /J90 /J180 / J360 ] [ Designated as safety issue: No ]
  
• Changes in anterior, mid and posterior vertebral heights of the treated vertebral body [ Time Frame: J-20 à J-7 / J6 / J45 /J90 /J180 / J360 ] [ Designated as safety issue: No ]
  
• Changes in height of the intervertebral disc spaces adjacent to the treated vertebra [ Time Frame: J-20 à J-7 / J6 / J45 /J90 /J180 / J360 ] [ Designated as safety issue: No ]
  
• Number of new vertebral fractures occurring during the one year follow-up period. [ Time Frame: J-20 à J-7 / J6 / J45 /J90 /J180 / J360 ] [ Designated as safety issue: Yes ]
  
• Cost evaluation in a sample of 10% of patients randomly selected including the following costs : o Intervention cost.o Medical treatment costs o Consultation costs. o Hospitalization cost o Complication costs [ Time Frame: J-20 à J-7 / J6 / J45 /J90 /J180 / J360 ] [ Designated as safety issue: Yes ]
  
• Follow-up of anterior, median and posterior height of the treated vertebral body, obtained by making an average of all measurements, on 3 cuts TDM on the sagittal level : lateral right, median and lateral left [ Time Frame: preoperative, at J6 and at J360 ] [ Designated as safety issue: No ]
  
• Intensity of signal with T2 sequence [ Time Frame: preoperative and at J360 ] [ Designated as safety issue: No ]
  

There is no reported frequency of stable thoracic or lumbar fractures traumatic fractures. However, the number of cases has been evaluated to be 61,425 yearly in Europe. Types A1 and A3.1 represent 61% of this number i.e. 37,468 per year in Europe and 4,600 in France.Conventional Conservative treatment of these fractures consists of brace and pain medication. However, a growing number of surgical teams use vertebroplasty or Balloon Kyphoplasty to avoid secondary fracture displacement after brace removal which results in increased kyphosis. However no study has compared the benefit of these new techniques to conservative managementThe goal of this study is to indicate if balloon kyphoplasty is able to restore vertebral height of the fractured vertebra better than Conservative Treatment.

1. The conventional orthopedic treatment is based on The Böhler Brace which extends from the manubrium to the pubic symphysis allowing spinal immobilisation in position of lumbar lordosis. Patients wear it for 3 to 6 months. It is a non-invasive treatment. However, kyphotic spine angle may increase over time despite the brace due to spine loading . 2 . Balloon Kyphoplasty is a variant of vertebroplasty which is performed under general anaesthesia using the KyphX® System (Medtronic., Sunnyvale, California). Balloon kyphoplasty aims at restore vertebral height of the fractured vertebra using an inflatable balloon prior to inject surgical cement (PMMA) into the vertebral body to fix the fracture. It is an expensive technique costing around 4,000 euros for up to 2 vertebrae in the same patient.

The surgical technique for the procedure has been described by Lieberman et al: A bilateral approach is chosen to insert working cannulas into the posterior part of the vertebral body through a posterior transpedicular approach. Fluoroscopy is used to insert the tools and control the procedure. With reaming tools, two working channels are created and the balloons are inserted. The balloons are available in lengths of 10, 15 and 20 mm.The two balloons(one on each side) should ideally be centered at middle height between the superior and inferior endplates and in the anterior two-thirds of the vertebral body. Balloon placement into the vertebral body is checked using radiopaque markers at the two extremities of the balloon. Once inserted, the balloons are inflated using visual, volume and pressure control to create a cavity. Inflation is stopped when one of the following inflation endpoints is reached: pressure raised over 400 psi, balloon contacts one of the cortical bone of the vertebra or reaching maximal balloon inflation volume. The balloons are then deflated and removed. The mean balloon inflation volume is 2 to 3ml. The Bone Filler Device, filled before with 1.5 ml of polymethylmethacrylate (PMMA), is then advanced through the working cannula towards the anterior part of the cavity and cement is slowly extruded by a stainless steel stylet, acting as a plunger. When the amount of cement from the first Bone Filler Device is delivered in the cavity, it is removed and another Bone Filler Device is advanced through the working cannula. This step is repeated till a complete fill of the cavity is obtained. The same procedure is repeated through the other working cannula at the contra-lateral pedicle. Filling of the cavity with highly viscous PMMA is performed under continuous fluoroscopic control.