Session I - Tibia Fractures

Detecting Intra-Articular Incongruity: A Comparison of Plain Radiographs versus Fluoroscopy

Michael McDermott, MD, Anthony Buoncristiani, MD, William Mills, MD, Geoffrey McCullen, MD, Alexander Shin, MD

Naval Medical Center, San Diego, California, USA

Purpose: Surgeons frequently rely on intra-operative fluoroscopy to assess the adequacy of reduction of intra-articular fractures. In our experience certain fractures appear less well reduced when plain radiographs are obtained post-operatively.

The purpose of this study is to determine if significant differences exist in the ability to assess intra-articular step-off when interpretation is based on plain radiographs versus fluoroscopy.

Methods: Fresh cadaveric specimens were dissected and pre-determined fracture patterns were created for several anatomic locations well known for intra-articular fractures: distal tibia, distal radius, radial head and proximal phalanx. A minimum of four, and as many as six, fractures were created for each fracture type. All fractures were then stabilized using standard fixation methods, creating varying pre-determined step-offs. Standard plain radiographic views for each fracture type were obtained for each specimen.

Fractures were randomized and each series of radiographs were then read by three blinded, independent observers. Corresponding live fluoroscopic images were then presented in a random fashion to the same observers and readings were obtained. Multiple trials were conducted in a similar fashion at one week intervals to minimize potential bias due to recall. The accuracy of the readings for each observer was then determined for each of the fracture types and statistical comparisons were made between plain roentgenograms and fluoroscopic images, in addition to calculations for inter-observer and intra-observer error.

Results: Each observer consistently read plain roentgenograms more accurately than corresponding fluoroscopic images for varying degrees of step-off in each of the fracture types, with the exception of proximal phalanx fractures where fluoroscopy was more accurately interpreted. Significant differences (p<0.05) were noted in each of the above fracture categories with the exception of the radial head. Statistical determinations for inter-observer and intra-observer error, in general, revealed that each observer was consistent in his interpretations and disagreement among observers was infrequent.

Discussion: Fluoroscopic examinations have often been used at our institution when assessing the adequacy of reduction of intra-articular fractures prior to leaving the operating suite. The convenient and timely manner with which these images can be obtained contributes significantly to their popularity. However, this study suggests that intra-articular step-off can more accurately be assessed using plain radiography rather than fluoroscopic images.

Conclusion: Anatomic articular reduction remains the goal. This cadaveric study suggests the importance of plain radiography in intra-articular fracture assessment. The adequacy of these reductions is measured in millimeters and therefore, the importance of utilizing the most accurate method of obtaining such a measurement cannot be overstated. Any gains in time or convenience are largely outweighed by the loss to the patient should a reduction be incorrectly accepted as adequate. This study suggests that plain radiography should be considered the primary method of assessing intra-articular reductions and adequate films should be obtained on every patient prior to leaving the operating suite.