Effect of needle brand, needle bevel grind, and silicone lubrication on contamination of joints with tissue and hair debris after arthrocentesis

Sarah Jane Waxman, Purdue University

Abstract

Arthrocentesis is a common procedure in equine veterinary medicine. Joint infection following arthrocentesis has been frequently reported. Investigations of the effects of hypodermic and spinal needle gauge and needle insertion techniques on contamination of the equine fetlock joint after arthrocentesis have found frequent tissue coring causing contamination of the joint with hair and tissue debris. This debris may be a source of bacteria that could lead to septic arthritis after an intra-articular injection. Our purpose was to investigate the effects of different manufacturers' brands of hypodermic needles; the absence of silicone lubrication of hypodermic needles; different types of bevel grind of hypodermic needles; and different manufacturers' brands and gauges of spinal needles on tissue and hair contamination of equine fetlock joints after arthrocentesis. We hypothesized: 1) different manufacturers' brands and bevel grinds of 20g hypodermic needles will have similar risks of joint contamination with tissue and hair debris; 2) non-lubricated hypodermic needles will increase the risk of joint contamination as compared to silicone-lubricated hypodermic needles; and 3) different manufacturers' brands and gauges of spinal needles will have similar risks of joint contamination with tissue and hair debris. Soft tissue flaps including joint capsule were completely excised from dorsal fetlock joints of anesthetized horses, leaving hair intact, and immediately mounted to a custom-made wooden testing frame. Tissues were harvested from horses admitted for euthanasia for reasons other than disease of the fetlock joints. Prior to excision, the skin surface was scrubbed for 1 minute with 4% chlorhexidine gluconate solution and then rinsed with sterile LRS. Both sides of the specimens were rinsed with sterile LRS prior to mounting. Needles were inserted through the joint tissues and 1mL of sterile saline was flushed through the needles into wells of a tissue culture plate. Wells were examined for tissue and hair debris under an inverted microscope at 4x magnification. The presence of tissue debris and hair debris in each well was determined as either present or absent. The number of hairs in each well and the number of hairs deposited on the synovial membrane was also noted for each needle variable. Three different manufacturer's brands of 20g hypodermic needles were compared, two different manufacturers' brands and two different gauges (20g and 22g) of spinal needles were compared, two different needle bevel grinds were compared, and 19g silicone lubricated and non-silicone lubricated hypodermic needles were compared. Associations were assessed using the Pearson χ2 or Fisher's exact test for categorical data. Separate mixed-effects multivariate logistic regression models were used to evaluate the associations between needle types and fetlock on the presence (yes/no) of hair or of tissue in wells post-injection. The final models with odds ratios (ORs) and 95% confidence intervals (95% CI) included only covariates with bivariate P-values < 0.20. The reference needle type for the models was a 20g, lubricated hypodermic needle. Statistical significance was set at P < 0.05. When all nine needle trials were combined, a total of 504 wells were examined, and 110 (21.8%) were contaminated with hair and 494 (98.0%) were contaminated with tissue. When needles were compared for tissue contamination, there was no statistically significant difference for OR between any needles tested (P ≥ 0.425). When needles were compared for total number of hairs in the wells and on the synovial membrane, ORs for the 19g lubricated needle and the 19g non-lubricated needle were significantly increased to 2.80 (95% CI 1.34-5.85, P = 0.006) and 8.29 (95% CI 3.96-17.35, P <0.001), respectively. OR for hair contamination for the 19g non-lubricated needle was 2.97 (95% CI 1.33-6.61, P = 0.008) when the reference needle was the 19g lubricated needle. Tissue fragments produced by 19g non-lubricated needles were larger than those produced by any other needle. No significant differences were seen between manufacturers' brands of 20g hypodermic needles, between needle bevel grinds, or between manufacturers' brands or gauges of spinal needles when compared for tissue and hair contamination. Both lubricated and non-lubricated 19g needles increase the risk for hair contamination of the equine fetlock joint compared to 20g lubricated needles following arthrocentesis. Non-lubricated needles increase hair contamination as compared to silicone-lubricated needles, and therefore we do not recommend using them for arthrocentesis unless the risks of increased contamination are accepted.

Degree

M.S.

Advisors

Adams, Purdue University.

Subject Area

Veterinary services

COinS