Treatment response in dogs with naturally occurring grade 3 elbow osteoarthritis following intra-articular injection of 117mSn (tin) colloid

Abstract

The radionuclide 117mSn (tin-117m) embedded in a homogeneous colloid is a novel radiosynoviorthesis (RSO) device for intra-articular (IA) administration to treat synovial inflammation and mitigate osteoarthritis (OA) in dogs. A study to evaluate tin-117m colloid treatment response in dogs with OA was conducted at two centers, the School of Veterinary Medicine at Louisiana State University, and at a referral practice in Houston, Texas. The tin-117m colloid was administered per-protocol to 14 client-owned dogs with radiographically confirmed, grade 3 OA in one or both elbow joints. Dog owners and attending clinicians assessed the level of pain at baseline (BL) and the post-treatment pain response at 90-day intervals for one year. Owners assessed treatment response according to a pain severity score (PSS) and a pain interference score (PIS) as defined by the Canine Brief Pain Inventory. Clinicians reported a lameness score using a 0–5 scale, from no lameness to continuous non-weight bearing lameness, when observing dogs at a walk and a trot. The rate of treatment success as determined by improved mean PSS and PIS scores reported by dog owners was >70% at all time points. Clinicians reported an improved mean pain score from BL at post-treatment Days 90 (p<0.05), 180, and 270. The dog owner and clinician assessments of treatment success were significantly correlated (p>0.05) at Day 90 and Day 180 time points. Results indicated that a single IA dose of tin-117m colloid provided a significant reduction in pain and lameness and improved functionality for up to a full year, with no adverse treatment related effects, in a high percentage of dogs with advanced, clinical OA of the elbow joint.

Safety and Clinical Response Following a Repeat Intraarticular Injection of Tin-117m (117mSn) Colloid in Dogs with Elbow Osteoarthritis

“…The possibility that tin-117m colloid can modify OA disease progression has been suggested. 24 The fact that there was no change in OA progression in approximately half the treated joints in PP dogs over a six-month period ( Table 3 ) would support this hypothesis. However, once joint remodeling and arthritic changes occur, reversal of this pathology is not possible.…”

“… 46 Evidence in this and earlier studies indicates that tin-117m can provide significant clinical benefit when used as a sole therapy. 22 , 24 , 29 , 31 Using tin-117m colloid with other treatment modalities is always an option; the device has no contraindications for use as a co-therapy. Radiosynoviorthesis is the only OA modality that selectively targets the synovium as the primary lesion in DJD.…”

“…A detailed description of the anesthesia protocol and injection procedure has been previously described. 24 , 31…”

“…In a study of dogs with more advanced grade 3 elbow OA, the success rate varied from 66.7% to 72.% depending on the post-treatment interval, which ranged from 90 to 365 days. 24 The study reported here is an extension of an earlier study that evaluated clinical effectiveness of tin-117m in dogs with grade 1–2 elbow OA. 31 Our objective was to determine if a repeat injection of tin-117m can be safely given in the same joint a year after the original IA dose, and if a favorable clinical response was observed six months after administration of the repeat injection (18 months after the original IA injection).…”

“…The radionuclide 117m Sn (tin-117m) embedded in a homogeneous colloid is a novel RSO designed for IA administration to treat synovial inflammation and mitigate OA in dogs. 22 , 24 , 28–31 In contrast to the high-energy beta radiation emitted by earlier RSO agents, tin-117m emits low-energy conversion electrons, which have a short, non-diminishing, well defined tissue penetration range of ~300 µm (0.3 mm), approximating the synovial thickness, and a t ½ if 14 days. 22 , 24 , 30 , 31 These properties give tin-117m radio-emissions a precise range of penetration that avoids exposing non-synovial tissues to radiation, and a duration of effect that spans several half-lives (approximately 42–90 days), sufficient to exert a sustained therapeutic effect for up to a full year.…”