Tissue sampling is non-inferior in comparison to sonication in orthopedic revision surgery

The value of sonication on orthopaedic implants in an everyday clinical setting - an exploratory study

BACKGROUND

Sonication of removed orthopaedic implants in suspected implant-associated infections (IAI) is widely applied internationally. However, evaluation of the utility of sonication on all implants removed in everyday standard practice is scarce. This exploratory study was performed to evaluate the application of sonication fluid (SF) culture on removed orthopaedic implants, irrespective of the reason for removal.

METHODS

Out of 100 removed orthopaedic implants collected between August 2019 and September 2020, 77 implants with availability of concurrent tissue culture samples were included in the study. Removed implants were categorized into a confirmed or suspected IAI group and a presumed aseptic group based on pre-operative diagnosis by the responsible surgeon. Implants were sonicated and SF culture performed under both aerobic and anaerobic conditions. The significance of all bacterial isolates was evaluated based on the CFU/mL cut-offs of the EBJIS guidelines, except for C. acnes where additional investigations were performed.

RESULTS

The results of SF culture in the two groups were compared with their corresponding tissue cultures. Out of the 12 cases in the confirmed/suspected IAI group, SF culture was positive in 11 cases and had increased diagnostic yield in two (17%) cases compared to tissue culture. Increased diagnostic yield of SF compared to tissue culture was seen in seven (11%) of the 65 implants in the presumed aseptic group. If growth of Cutibacterium species isolates were interpreted based on EBJIS cut-off for SF culture instead of the study-specific criteria, then two isolates considered to represent infection might have been missed while three other isolates considered contaminants would have fallen under the 'infection confirmed' category in the EBJIS guidelines.

CONCLUSION

Sonication with SF culture has increased diagnostic yield compared to tissue cultures in all implants irrespective of reason for removal. However, positive SF cultures with Cutibacterium species should always be interpreted with extreme care.

Revision surgery after failed surgical treatment of midshaft clavicle fractures is often associated with positive detection of bacteria

BACKGROUND

Midshaft clavicle fractures are common, and the proportion of patients treated surgically has increased in recent years. With this increase in surgical treatments, the complication rate, for instance of infection, non-union, or implant failure, has also risen. This study evaluates the frequency of pathogen detection during revision surgeries occurring after a prior failed osteosynthesis of midshaft clavicle fractures.

METHODS

All patients treated in our hospital with a prior failed surgical therapy of a clavicle midshaft fracture between January 2013 and March 2022 were screened. Epidemiological data, intraoperative tissue samples, sonication, and the type of revision surgery were assessed. A postoperative follow-up at a minimum of 6 month was defined and osseous consolidation was verified.

RESULTS

Twenty-one patients (twelve male and eight female) were included with a mean age of 40.4 ± 14.1 years. Eleven of the patients showed pathogen detection (Group I), and seven remained without (Group II). A significant difference in age existed between Groups I and II (36.1 ± 12.8 and 51.6 ± 11.5, p  ≤ 0.05). The three most common pathogens were Cutibacterium acnes (n = 7), Staphylococcus epidermidis (n = 4), and Staphylococcus sacchorlyticus (n = 3), respectively. Thirteen patients presented for a follow-up. In nine patients (69%), bone healing was detectable. Four patients received a second revision surgery.

CONCLUSION

Revision surgery frequently shows pathogen detection without signs of infection. Cutibacterium acnes is the most common pathogen. Despite pathogen detection, bone healing can be achieved with revision surgery, although the rate of repeat revision surgeries is high.