Utility of conventional radiographs in the detection of traumatic knee arthrotomies: a retrospective cohort review

Abstract

Background: The most common method to determine a traumatic knee arthrotomy is the saline load challenge. Recent literature has suggested high false-negative and false-positive rates using this method and also has shown that CT was effective in detecting these arthrotomies. The purpose of this study was to evaluate another method of diagnosing these injuries. We hypothesized that plain radiographs of the knee could be an effective alternative study in diagnosing a traumatic arthrotomy. Methods: After institutional review board approval, this retrospective cohort review identified 32 patients diagnosed with a traumatic arthrotomy by direct visualization in the operating room and another 32 patients with no evidence of traumatic arthopathy, according to the surgeon. The preoperative anteroposterior and lateral radiographs from both cohorts were blinded and randomized and then submitted to a radiologist to review for the presence of air in the joint space. Sensitivity and specificity were calculated based on radiographic review compared with the gold standard of direct visualization. Results: Plain film anteroposterior and lateral knee radiographs had a sensitivity of 78.1% and a specificity of 90.6% with a positive predictive value of 89.3% for diagnosis of traumatic arthrotomy in our cohort. Conclusions: Our study suggests that radiographs, which are obtained as standard of care during work-up of knee injuries, have a relatively high sensitivity and specificity and can be used as an adjunct to help diagnose a traumatic arthrotomy of the knee joint. Level of Evidence: Level III.

Battle Royale

“…Radiographs are used to evaluate for foreign body, fracture, and intra-articular air. A retrospective cohort study showed that AP and lateral radiographs of the knee had a sensitivity of 78.1% and a specificity of 90.6% for the detection of pneumoarthrosis when the radiologists were prompted to look for intra-articular air 3 . This raises the question of whether the initial emergency evaluation should include a short description of the injury and the concern for TA to properly key in the radiologist on what to look for.…”

“…This was strengthened by the benefit of removing "operator error" of needle placement, patient procedural pain, and that imaging can be interpreted quickly by the radiologist and orthopedist when compared with the SLT. CT imaging has an increased cost reported to range between approximately $182 and $245, whereas the SLT without a cost comparison would be considerably less 2,3 . CT also carries increased radiation exposure compared with other diagnostic tests; compared with a computed radiograph of the knee, CT of the knee has over 10 times the effective radiation dose.…”

“…The standard workup for concern of TA is obtaining radiographic imaging (foreign body, fracture, and air within the joint) and direct wound observation. Sleasman et al 3 highlighted that radiographic imaging was highly sensitive (78.1%) and specific (90.6%) for detecting knee arthrotomies but noted that a large percentage of radiologists initially missed or did not note TA until reviewed for this diagnosis. This limits in some ways the use of radiographs because the single tool for diagnosis and whether other imaging may be more beneficial.…”