Effect of different irrigation fluids on human articular cartilage: an in vitro study.

Purpose: The goal of this study was to examine the effect of different irrigation fluids on human articular cartilage.

Methods: Femoral heads were obtained from 9 patients with fractured neck of femur (mean age, 89 years; 7 female) and tibial plateaus from 2 female patients at the time of total knee replacement (mean age, 73 years). Chrondral explants were harvested and exposed to 1 of 4 different irrigation fluids for 1 hour: Ringer's solution, normal saline (0.9% NaCl), 1.5% glycine, or 5% mannitol. M199 culture medium was used as a positive control, and 0.5% bupivicaine, previously shown to be harmful to articular cartilage, as a negative control. After exposure, explants were incubated with radiolabeled sulfate ((35)S0(4)), and uptake was measured after 16 hours as an indicator of proteoglycan synthesis.

Results: (35)S0(4) uptake was inhibited 10% by Ringer's solution (P = .3), 24% by 1.5% glycine (P = .08), 31% by 5% mannitol (P = .03), 35% by normal saline (P = .04), and 90% by 0.5% bupivacaine (P < .001), compared with the M199 control. Comparisons of the different solutions showed that all solutions were less inhibitory than 0.5% bupivacaine (P < .001). The only significant difference was that between normal saline and Ringer's solution (P = .03).

Conclusions: In an in vitro model of human articular cartilage, Ringer's solution had the least effect on cartilage metabolism, and normal saline caused the greatest inhibition of cartilage metabolism.

Clinical Relevance: Normal saline, the most commonly used irrigation fluid, may have an inhibitory effect on proteoglycan metabolism in articular cartilage. Additional studies are required to assess the potential damage to cartilage from normal saline in the clinical setting.