Contamination of joints with tissue debris and hair after arthrocentesis: the effect of needle insertion angle, spinal needle gauge, and insertion of spinal needles with and without a stylet.

The research involves evaluation of different variables during arthrocentesis (a procedure where fluid is aspirated from a joint using a needle) on horses, and their impact on the contamination of the joint with tissue debris and hair. The study concludes that an angled needle insertion and use of 22g spinal needles with a stylet in place reduces joint contamination and should be preferred in arthrocentesis of fetlocks.

Studies and Methods

• The study was an experimental one carried out on the fetlock joint tissues of 10 horses.
• Tissue flaps, including the joint capsule, were dissected from dorsal fetlock joints of 7 anesthetized horses ensuring the proximal base remained intact.
• Different types and gauge of needles were inserted through the tissue flaps into tissue cell culture plates, which were then examined for any debris.
• The study design included various variables like the type and gauge of the needle, use of spinal needles with and without a stylet, angle of insertion, length of hair, and ante- and post-mortem needle insertion.

Outcomes and Results

• The odds ratio (OR) for hair contamination was high for 20 g spinal needles inserted without a stylet and low for 22 g spinal needles inserted with a stylet and for needles inserted at an angle.
• The OR for tissue contamination was significantly low for 20 g spinal needles inserted without a stylet, with angled insertion, and where hair was clipped.
• Bacteria were also found in 2.6% of the tissue fragments used.

Conclusions and Implications

• The study concludes that the risk of joint contamination with tissue and hair could be reduced by angling the needle during insertion.
• In addition, using a 22 g spinal needle with the stylet in place is preferable to a 20 g spinal needle.
• The presence of bacteria in some tissue samples indicated that even with routine surgical preparation of skin, joint contamination could still occur.