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Samarium 153‐Labeled Hydroxyapatite Microspheres for Radiation Synovectomy in the Horse: A Study of the Biokinetics, Dosimetry, Clinical, and Morphologic Response in Normal Metacarpophalangeal and Metatarsophalangeal Joints
Author(s) -
Yarbrough Tom B.,
Lee Mark R.,
Hornof William J.,
Koblik Phil D.,
Brodack Jim,
Troup Cathy,
O'Brien Timothy R.,
Pool Roy
Publication year - 2000
Publication title -
veterinary surgery
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 79
eISSN - 1532-950X
pISSN - 0161-3499
DOI - 10.1111/j.1532-950x.2000.00191.x
Subject(s) - medicine , lameness , metatarsophalangeal joints , horse , metacarpophalangeal joint , synovectomy , nuclear medicine , surgery , rheumatoid arthritis , paleontology , thumb , biology
Objective— To determine the effects of Samarium‐153 bound to hydroxyapatite microspheres ( 153 SmM) when injected into the metacarpophalangeal and metatarsophalangeal joints of horses. Study Design— Horses were injected with 153 SmM in metacarpophalangeal and metatarsophalangeal joints with the diagonal contralateral joints used as untreated controls. Animals or Sample Population Twelve adult horses without pre‐existing disease involving the metacarpo/metatarsophalangeal joints. Methods— Horses were divided into three groups: high‐dose Samarium‐153 (12.5 to 17.0 millicurie [mCi]), intermediate dose (6.5 to 12.0 mCi), and low dose (3.5 to 6.0 mCi). Horses were examined daily for 7 days postinjection for clinical abnormalities, lameness, and surface and systemic radiation levels. One horse from each group was euthanatized at 14, 30, and 60 days postinjection and the effects of the 153 SmM examined microscopically in the cartilage and synovial membrane. Results— Intraarticular 153 SmM caused inflammation characterized by lameness, effusion, and regional edema for 48 to 72 hours. Minimal levels of active 153 SmM were identified in the blood or urine and were well below the maximal tolerance of 1 mCi. Microscopically the radiation caused no effects on the articular cartilage. The synovectomy created was good but not ideal in that some areas did have necrosis into the subintimal regions and a few islands of intact intimal cells persisted. Conclusions— The use of 153 SmM is an effective means of targeting the synovial intimal cells with minimal extrasynovial leakage of radiation. Clinical Relevance— The metacarpophalangeal and metatarsophalangeal joints of the horse can be safely treated with 153 SmM without damage to the cartilage or significant extracapsular leakage.