[Effectiveness evaluation of knee joint 90Y radiosynovectomy]

Chronic knee synovitis with effusion, because of the special role of knee joint is an important therapeutic problem. This leads to searching for new treatment modalities. One of them is radiosynovectomy based on anti-proliferative and anti-inflammatory activity of ionizing radiation. It is made using 90Y mainly (high energy of beta [electrons] radiation [2.2 MeV], large average penetration in soft tissues [3.6 mm] and long physical half-life [2.7 days]).

Analyzed material is comprised of 30 patients (33 treatments) suffering from proliferative synovitis of knee joint treated by radiosynovectomy using intra-articular injection of 6 mCi 90Y. In 20 cases the reason of disease was non-specific reactive arthritis, in 5 rheumatoid arthritis, in 3 villonodular synovitis, in 3 psoriasis and in 2 ulcerative colitis. Symptoms duration varied from 3 to 144 months (mean 43). A knee circumference at the treatment day varied from 33.5 cm to 49 cm (mean 41). The operation was based on knee biopsy, evacuation of exudate and delivery of 6 mCi of colloid 90Y. Follow up ranged up to 14 months (mean 4.4). Patients were examined 2 weeks, 1, 3, 6 and 12 months after treatment. During examination a knee circumference was measured, a knee mobility, temperature and patella floating symptom were examined. Pain in treated region was assessed and amount of exudate was measured.

A knee circumference and exudate amount enlarged during following controls, and compared between the treatment day and the last control did not differ significantly (41 vs. 41.6 cm and 43 vs. 42.5 ml respectively) but number of biopsies decreased. A percentage of patients with impaired knee mobility also did not change (59% vs. 58%). Probably, it was caused by resignation from control examination when symptoms disappeared. A percentage of patients without pain relief decreased from 43.5% 2 weeks after treatment to 20% one year later and a patient percentage with complete pain relief increased from 8.5% to 60%. A patient percentage with increased knee temperature and with floating patella decreased significantly (54 vs. 25% and 83 vs. 48% respectively).

Obtained results do not allow to form univocal conclusions regarding effectiveness of 90Y radiosynovectomy. The decreasing biopsies number, decreasing percentage of patient with increased knee temperature and with floating patella; increased percentage of patients with analgetic effect and with total pain relief show a necessity of renewed evaluation of this treatment modality on the base of bigger patients number and longer and more precise observation.