Comparison of the effect of knee synovectomy in haemophilic patients with153Sm- and90Y -labelled hydroxyapatite 1 year after

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

INTRODUCTION

Radiosynovectomy (RS) with ⁹⁰Y-hydroxyapatite (⁹⁰Y-HyA) aims to control knee hemarthrosis in hemophiliac patients to prevent secondary arthropathy. However, knee RS using ¹⁵³Sm-hydroxyapatite (¹⁵³Sm-HyA) is considered less suitable due to the lower average soft tissue range and energy of ¹⁵³Sm for large joints, such as the knees.

PURPOSE

The objective of this investigation was to assess the efficacy and safety of knee RS with ¹⁵³Sm-HyA, compared to ⁹⁰Y-HyA.

METHODS

Forty patients were prospectively assigned to undergo knee RS with ¹⁵³Sm-HyA (n = 19) or with ⁹⁰Y-HyA (n = 21). The frequency of hemarthrosis episodes before and after treatment were compared.

RESULTS

After six months of knee RS, ¹⁵³Sm-HyA and ⁹⁰Y-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 ¹⁵³Sm-HyA (87.5%) compared to ⁹⁰Y-HyA (50.0%). This discrepancy was more pronounced (p = 0.002) for ¹⁵³Sm-HyA compared to ⁹⁰Y-HyA in adults/adolescents.

CONCLUSION

Knee radiosynovectomy with ¹⁵³Sm-HyA is safe, reduces hemarthrosis episodes after 12 months of treatments, especially in adults/adolescents and even with grades III/IV arthropathy, similar to ⁹⁰Y-HyA. ⁹⁰Y-HyA seems to promote better hemarthrosis control in small children.

Outpatient treatment for haemophilic arthropathy with radiosynovectomy: Radiation dose to family members

One of the key features of good practice in medicine is the doctor-patient communication. Radiation protection standards for radiosynovectomy (RS) is limited. Yttrium-90 is a beta-emitting radioisotope used in RS to treat joint pain from haemophilic arthritis. ICRP 94 states that if a patient is treated with up to 200 MBq, there is no need for further precautions when it comes to public exposure, however, activities can go up to 370 MBq in RS for the knee. This study analysed 119 family members' safety (16.7% pregnant women). The ambient dose equivalent rate was measured within four distances. A survey was carried analysing risk groups and time spent next to patients. Results showed that family members should be advised to remain at 1.0 m from the patient to decrease accumulated dose by 97.6%. The dose per activity factors estimated in this study is also a useful tool during the risk assessment and doctor/patient communication. Pamphlets were distributed with radiation protection recommendations. Ambient dose equivalent was low enough to show that RS is a safe procedure for family members, which is essential to promote adherence to RS in countries where it is needed but not performed due to lack of information on radiation safety.