Knee radiosynovectomy with 153 Sm-hydroxyapatite compared to 90 Y-hydroxyapatite: initial results of a prospective trial.

Introduction: Radiosynovectomy (RS) with ⁹⁰ Y-hydroxyapatite ( ⁹⁰ Y-HyA) aims to control knee hemarthrosis in hemophiliac patients to prevent secondary arthropathy. However, knee RS using ¹⁵³ Sm-hydroxyapatite ( ¹⁵³ Sm-HyA) is considered less suitable due to the lower average soft tissue range and energy of ¹⁵³ Sm for large joints, such as the knees.
Purpose: The objective of this investigation was to assess the efficacy and safety of knee RS with ¹⁵³ Sm-HyA, compared to ⁹⁰ Y-HyA.
Methods: Forty patients were prospectively assigned to undergo knee RS with ¹⁵³ Sm-HyA (n = 19) or with ⁹⁰ Y-HyA (n = 21). The frequency of hemarthrosis episodes before and after treatment were compared.
Results: After six months of knee RS, ¹⁵³ Sm-HyA and ⁹⁰ Y-HyA promoted a similar reduction of hemarthrosis episodes (50% and 66.7%, respectively). However, after 12 months of knee RS, the reduction of hemarthrosis episodes was significantly (p = 0.037) higher using ¹⁵³ Sm-HyA (87.5%) compared to ⁹⁰ Y-HyA (50.0%). This discrepancy was more pronounced (p = 0.002) for ¹⁵³ Sm-HyA compared to ⁹⁰ Y-HyA in adults/adolescents.
Conclusion: Knee radiosynovectomy with ¹⁵³ Sm-HyA is safe, reduces hemarthrosis episodes after 12 months of treatments, especially in adults/adolescents and even with grades III/IV arthropathy, similar to ⁹⁰ Y-HyA. ⁹⁰ Y-HyA seems to promote better hemarthrosis control in small children.