Intra-articular injections of ketamine and 25% dextrose improve clinical and pathological outcomes in the monosodium iodoacetate model of osteoarthritis.

BACKGROUND: The study evaluated the effect of intra-articular injections of ketamine and 25% dextrose with triamcinolone acetate (TA) and hyaluronic acid (HA) on joint pathology and pain behavior in monosodium iodoacetate (MIA)-induced osteoarthritis (OA) in experimental mice.

METHODS: In phase I, the MIA-induced OA model was standardized. In phase II, mice were divided into three groups: disease controls (DC), ketamine 12 mg/kg (K12) and ketamine 24 mg/kg (K24) to select an effective dose of ketamine for phase III. In phase III, the groups were: DC, normal controls (NC), K24, 25% dextrose (D25) - 10 μL, TA 6 mg/kg, and HA - 3.5 mg/kg. The effect of ketamine was compared with the standard drugs - TA and HA. In phases II and III, after 7 days following the induction of OA, animals were subjected to weekly behavioral tests and biweekly drug administration from week 2 to week 4. Subsequently, after 4 weeks knee joint samples were collected and sent for histopathological evaluation to a veterinary pathologist.

RESULTS: In phase I, the DC group showed significant OA changes as compared to NC on knee joint histopathology scoring. In phase II, all the behavioral tests and knee joint histopathology results demonstrated a significant improvement with K24 as compared to DC. In phase III, significant differences were found between DC vs. HA, DC vs. D25, DC vs. K24, K24 vs. TA, HA vs. TA for open field test and hot plate test (p<0.001), whereas HA and ketamine showed comparable results for these tests. There was a significant improvement in D25, TA and K24, HA groups as compared to DC in histopathology scores, (p<0.05).

CONCLUSIONS: The NMDA antagonist effect of ketamine and the proliferative effect of 25% dextrose showed a reduction in pain and disease activity in the OA model.