Abstract
Aim
Radiologic signs such as radiolucent lines around the implant, hardware fracture or displacement and periosteal reaction have been considered suggestive of implant-associated infection. The goal of this study is to assess the correlation of these signs with confirmed internal fixation-associated infection evaluated in a prospective cohort.
Method
We evaluated the radiologic appearance of preoperative standard x-ray images in 421 surgeries performed in 380 patients with internal fixation device in place (56.8% male, mean age 53 ± 17 years). This prospective study was performed in a large single center for musculoskeletal surgery from 2013–2017. Infection was suspected preoperatively in only 23.8% of the surgeries. The most common indications for surgeries in which infection was not suspected were nonunion (84 cases) and symptomatic hardware (57 cases). All removed implants were sent to sonication for biofilm removal and detection. In addition, several peri-implant tissue samples were collected. Radiographs were analyzed in a blinded fashion for signs of radiolucent lines around the implant before removal, hardware fracture or displacement, and soft periosteal reactions suggestive of infection. Diagnosis was established according to the IDSA criteria for PJI. Contingency tables were constructed to determine sensitivity and specificity, and to perform Chi-square tests to compare the presence of infection with radiological signs of infection.
Results
Radiologic signs suggestive for infection were uncommon, including radiolucent lines in 48 cases (11.4%); hardware breakage in 542cases (12.4%); hardware displacement in 45 cases (10.7%); periosteal reaction in 30 cases (7.1%). Infection was confirmed in 27.6% of the surgeries, and radiological signs of infection were only marginally more common in this group. Only the presence of radiolucent lines (p = 0.47; OR = 1.86 [95% CI 1.00 – 3.38]) and periosteal reaction (p = 0.15; OR = 2.48 [1.17 – 5.26]) were significantly associated with confirmed infection. Sensitivity of radiolucent lines and periosteal reaction were low (16,4% and 12,1%, respectively), while specificity remained acceptable (90.5%and 94.8%, respectively).
Conclusions
Radiologic signs of infection are uncommon, even in the context of a confirmed infection. Radiolucency surrounding the implant and the presence of a soft periosteal reaction were significantly associated with the presence of infection, though sensitivity of the signs remained very low.
