Assess the postoperative functional outcomes after surgical correction of skeletal deformities of lower limbs in osteogenesis imperfecta patients as regard ambulation status, postoperative complications and reoperation rate.

Osteogenesis imperfecta (OI) is a rare heterogeneous group of inherited disorders characterized by brittle bones, frequent fractures, and skeletal deformities that affect an individual's ability to walk. Based on Sillence classification, there are four types of OI; Type I (mild, non-deforming), Type II (perinatal lethal), Type III (severely deforming), and Type IV (moderately deforming). Recently 3 types added type V, VI and type VII.

Deformities of the long bones are common in patients with osteogenesis imperfecta particularly in the lower limbs Where they are also more severe. Multiple fractures can occur and the ability to walk may be compromised.

The goal of orthopaedic surgery implies the correction of long bone bowing, rotational malalignment, angular deformity and prevention or reduction of the fracture incidence .Surgical intervention in the form of multiple osteotomies, realignment and fixation by intramedullary rods can correct deformity of the long bones and provides internal support enhancing the potential for standing and assisted or independent walking Sofield and Millar, Page and Mead popularized the operation of multiple osteotomies and fixation by intramedullary rods. In 1963 the baily dubow nail was first introduced The telescopic rodding and nailing have been developed in order to obtain a long lasting osteosynthesis in a growing long bone, thus, reducing the need of replacement. The evolution of telescoping rods for the treatment of fractures and deformity in children with diminished bone Quality has resulted in an approved and commercially available new single entry telescopic rod system, the Fassier Duval Telescopic IM System (FD-rod).

In recent publications a high reoperation rate for proximal rod migration and a complication rate up to 40% because of rod migration, limited telescoping and joint protrusion was found.

We hope that our study will advance the proper surgical intervention for children with osteogenesis imperfecta for better functional outcomes

Inclusion Criteria:

• Age from 3-11 years
• Severe lower limb deformity presented with or without fracture

Exclusion Criteria:

• Nondisplaced/incomplete fractures in minimally deformed bones
• Deformity angulation less than 20 degree

all Osteogenesis imperfecta patients admitted at assiut university pediatric and main hospitals with age range 3- 11 years old presented with lower limb skeletal deformities with or without fracture will be included in our study