Fate Of Hydroxyapatite Crystals Used As Bone Graft Substitute In Benign Lytic Lesions Of Long Bones

Abstract

Background: Benign lytic lesions of bone most commonly treated with curettage which creates defect. Defects are usually filled with autogenous bone graft. Alternatively hydroxyapatite crystals may be used to overcome the donor site morbidity of autogenous bone grafting. Our purpose of study was to depict the fate of hydroxyapatite crystals in these lesions. Method : We treated 5 cases of giant cell tumour, 5 cases of simple bone cyst and 2 case of aneurysmal bone cyst, who presented with lytic lesion of long bones, by curettage alone and application of hydroxyapatite crystals. The patients were selected according to inclusion and exclusion criteria’s. These patients were followed up for 36 month. Radiographic evaluation was done according to IRWIN grading, stage I (obvious margins), stage II (hazy margins) and stage III (obvious incorporation). Observation: We found no rejection of implanted hydroxyapatite crystals. In maximum of 13 month all cases show incorporation of hydroxyapatite crystals to host bone. Out of 12 cases final Irwin grading was III in 10 cases(83.33%) and II in 2(16.67%) cases. Absorption of hydroxyapatite crystals is very slow process, even in three year follow up, very little hydroxyapatite crystals was absorbed. Union and remodelling of bone in pathological fracture was normal. There was no collapse of graft on weight bearing. During followup period, haematological and blood biochemical parameters stayed within normal limit. No long term complication seen in any case with hydroxyapatite crystals except recurrence of tumour seen in two cases. Conclusion: Hydroxyapatite crystals are slowly absorbed by body. Bone ingrowth and bone formation around the hydroxyapatite crystals are excellent. Hydroxyapatite crystals have great biological safety, good biocompatibility & good bone conduction.