Saturday, February 15, 2020

Can joint aspiration rule out an infection?

The accuracy of joint aspiration for the diagnosis of shoulder infections

These authors performed 106 aspirations with fluoroscopic guidance between 0 and 179 days before a revision surgery. Native joints and post–fracture repair, post-arthroscopy, and post-arthroplasty shoulders were included.

They were able to sample intra-articular liquid directly in 60 cases and after saline solution injection in 43 cases, whereas 3 cases remained unsuccessful.

According to intraoperative samples, 24 shoulders were infected but only 10 of 24 (42%) yielded pathogens in the aspirate. 

Among the 43 saline solution–enforced irrigations, none revealed bacteria but 8 (17%) had confirmed infection based on intraoperative samples. 

The most common pathogens were Cutibacterium acnes (50%) and Staphylococcus aureus (33%).

Altogether, aspiration missed 16 of 24 confirmed infections (67%): 8 in the successful aspiration group and 8 after saline solution irrigation.

The missed microorganisms were  all gram positived C acnes (n . 10), S aureus (n . 5), and Staphylococcus warneri (n . 1) and were equally distributed between successful aspirations and dry tap cases.

Comment: As these authors point out, presurgical shoulder joint aspiration is not reliable in excluding shoulder joint infection. Nevertheless, a positive aspiration finding can guide clinical decision making. As we try to explain the utility of an aspiration, we compare it to a needle biopsy: a positive result can be used to diagnose cancer, but a negative biopsy cannot exclude the diagnosis.

The results of this study do not support the use of irrigation as a means of gathering information from shoulders without joint fluid.

Finally, aspiration may be of use in cases where infection is strongly suspected in hopes of identifying the organism so that specific antibiotic therapy can be instituted immediately after surgery.

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We have a new set of shoulder youtubes about the shoulder, check them out at this link.

Be sure to visit "Ream and Run - the state of the art" regarding this radically conservative approach to shoulder arthritis at this link and this link

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