BONE-MARROW TRANSPLANTATION (BMT) AND COR RECTION OF BONE ABNORMALITIES ASSOCIATED WITH SICKLE-CELL DISEASE (SCD)

Purpose of the study Allogenic B.M.T. has been investigated as a curat ive treatment of anemia in S.C.D. Furthermore, correction of functiona l asplenia has been observed after B.M.T.; it remains to be determined if such a treatment may reserve other organe damage and particularly bone abnormalities and osteonecrosis frequently associated with S.C. h emoglobinopathies. Material and methods The aim of this retrospective review was to evaluate the radiologic and MRI results of 2 patients wi th avascular necrosis before the B.M.T. Roentgenographic diagnosis of osteonecrosis before B.M.T. included, for the 2 patients, depression a nd fragmentation of the articular surface. MRI imaging of the bones of these patients observed before B.M.T. a decreased signal intensity re lative to subcutaneous fat on the short TR/TE images instead of the hi gh signal intensity of the usual fatty marrow in epiphysis. Results On ly three months after the B.M.T., osteonecrosis appeared to have heale d without deformity for the two patients. Furthermore, MRI imaging of the bones at three months after B.M.T. observed a high signal intensit y in the epiphysis corresponding to a yellow marrow. Discussion Becaus e of the stress on the marrow system in children with severe chronic h emolytic anemia, red marrow remains hyperplastic and extensive through out the body and normal red marrow conversion to fat marrow is postpon ed in S.C.D.; marrow infarction in S.C.D. develops in red marrow; sinc e red marrow persists in the epiphysis in S.C.D., these patients have these sites for potential infarction. Our observation shows MRI change s in the epiphysis and diaphysis marrow after B.M.T.; the appearance o f the marrow changes after transplantation in these patients may refle ct hemodynamic and physiologic phenomena attributable to the combined effects of the pretransplant chemotherapy and new bone marrow reconsti tution after transplantation. This tendency of normalization of the ep iphysis with red-yellow marrow conversion after B.M.T. is important si nce it is a reduction of the potential sites for infarction. This red- yellow marrow conversion after B.M.T. may also explain the velocity of the reconstruction of the epiphysis after osteonecrosis; if osteonecr osis may heal without deformity in the prepubertal epiphysis of childr en, it takes usually 5 or 6 years and this phenomena is very uncommon; healing was here observed only 3 weeks after B.M.T.; the effect of th e B.M.T. on the reconstruction of the epiphysis may be explained by th e following hypothesis: hematopoietic marrow of the epiphysis in S.C.D . had a rich sinusoidal system fed by several epiphyseal vessels; bloo d flow in the sinusoidal system is sluggish and the biochemical enviro nment in this area facilitates the sickling process; blood containing sickled cells had high viscosity and produces a relative obstruction t o blood flow in the sinusoidal system of the epiphysis. When sickled r ed cells are replaced with normal cells after B.M.T., bone circulation in the epiphysis is restored and allowed quick reconstruction when os teonecrosis is present. Conclusion This study seems to demonstrate tha t bone abnormalities associated with S.C.D. are reversible after B.M.T ., phenomena of critical importance to support the eventual role B.M.T . as a curative treatment in S.C.D.