Tibial fibrous dysplasia in children treated by Ilizarov Technique- A review of treatment options

Fibrous dysplasia is a pathological condition, where normal medullary bone is replaced by fibrous tissue and small, woven specules of bone. Fibrous dysplasia can occur in epiphysis, metaphysis or diaphysis. Occationally, biopsy is necessary to establish the diagnosis. We present a review of operative treatment using the Ilizarov technique.


Introduction
The management of tibial fibrous dysplasia in children are curettage or subperiosteal resection to extra periosteal wide resection followed by bone transport. Here, enbloc excision followed by distraction osteogenesis is our main treatment technique. In few cases we did osteotomy in the true apex of the deformity and 2 smooth 1.5 k/wires were introduced in the medullary cavity to maintain the axis and to prevent axis deviation. In this situation Ilizarov frame was applied with only the biocompatible thin wires. In the same sitting we can correct the deformity acutely. The potential advantage is to increase the bone regenerate. 1,2 We describe 18 cases of fibrous dysplasia in tibia, in which 12 cases were treated by enbloc excision with bone transportation and 6 cases were treated by only application of Ilizarov with corrective osteotomy in the CORA, by putting the 1.5 mm two k/ wires in the medullary cavity.

Materials and methods
A total of 18 patients were treated between January 2010 -January 2020; 12 patients came with pain and 6 with pain and deformity. All patients were treated by Ilizarov technique. Age ranges from 4-14 years. 12 patients by enbloc excision and bone transportation and 6 patients were treated by osteotomy at the true apex of the deformity by introducing the k/wires in the medullary cavity with stable fixation by Ilizarov device. The longest duration for bone transport was 16 weeks (14-20 weeks), and only for application, after deformity correction was 20 weeks. We have never used any kind of bone grafts.

Results
All the 18 patients were treated successfully by Ilizarov compression distraction device. The patients with localized tibial pathology with deformity had the shortest period on the Ilizarov apparatus, 14 weeks.

Discussion
There are varieties of treatment options in the literature, starting from casting, intramedullary nailing, plate and external fixator. Each with variable success rate and complications. The aim of this review was to showcase the outcomes with Ilizarov device. This is a unique tool with good outcomes and we are getting very less complications like wire track infection and that can be managed by local proper dressing and application of antibiotics. Fibrous dysplasia is caused by the sporadic mutation of the GNAS1 gene located on the chromosome of the osteoblastic cells. 3 Fibrous dysplasia may occur in any bones. Fibrous dysplasia presents clinically in children and adolescents, with a median onset age of 5 years. Monostotic fibrous dysplasia is active and it became inactive after puberty. 4 Children seek medical care because of either painful swelling and deformity or a pathological fracture through a weakened bone. Radiographically, monostotic fibrous dysplasia include a ground glass appearance with expansion of bone and sclerosis surrounding the lesion. 5 MRI does not provide characteristic appearance of fibrous dysplasia. 6 In our series we performed Ilizarov technique that in two ways: a. We resected the whole tumor and then transported the bone after application of stable Ilizarov apparatus.
b. 2nd one, in the true apex of the deformity, we did osteotomy and put the 1.5 mm guide wires to increase circulation in the medullary cavity.
We have not done the intralesional curettage and bone grafting. Ilizarov technique has been well documented with good outcome in treating fibrous dysplasia by applying load and motion which gives good healing in pathologic area. 5 Compression refers to the formation of new bone between the bony surface. It gives neovascularization, which is actually simulates the new bone formation. In addition, there is histogenesis of muscles, nerves, skin and disease like fibrous dysplasia. This new bone replaces pathological bone with normal bone. Due to its versatility, the Ilizarov apparatus allow 3-dimensional correction of deformity. The technique gives stability and creates mechanical force to induce the new bone formation which is compatible to Ilizarov's law of tension stress. 7 The local blood supply and the integrity of the periosteum are well preserved by minimally invasive transosseous wires or when corticotomy is necessary. 8 When vascularity is preserved at fracture site, the bone will unite within the normal healing period. 9 And the greatest advantage after application of the Ilizarov apparatus is early weight bearing. Weight bearing is considered to be essential both for bone regeneration and consolidation.  Histopathology report:
Sections code: A) All soft tissue embedded on one block, B) All soft tissue embedded on one block.

Microscopic description:
Sections from the submitted specimen reveal a lesion composed of Chinese figure-like trabeculae of woven bone within a proliferating Fibroblastic stroma. Osteoblastic rimming of these trabeculae is seen. No granuloma or evidence of malignancy is seen.

Histologic diagnosis:
Tissue from tibia, left: Consistent with