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Lateral radiographs ineffective for confirming tibial plafond fracture reductions
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Results of a cadaveric study showed lateral ankle fluoroscopy images do not fully reveal all the features of reduced tibial plafond fractures and that orthopedic surgeons need to better understand the extent of what those images can show.
The study, conducted by Matthew L. Graves, MD, and colleagues, was designed to determine how well experienced orthopedic surgeons understand lateral radiographs of reduced tibial plafond fractures through two hypotheses.
The problem is that “the lateral radiographs are really important, but do not seem to always correlate with what we are seeing on the sagittal CT reconstructions,” Graves said at the 2010 Annual Meeting of the American Academy of Orthopaedic Surgeons.
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The 5-mm sections researchers made can be seen in one of the cadaver ankles used in their study, which investigated how lateral radiographs were affected when the sections were malrotated. Images: Graves ML |
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To test the first, whether the subchondral shadow on “perfect” lateral radiographs of six rigidly fixed fresh-frozen tibial plafond cadaveric specimens is created equally by the medial, central and lateral portion of the distal tibia, they removed osteochondral segments of each specimen medially to laterally, taking an X-ray after removing each segment. They also performed the segmental removal process laterally to medially and took radiographs after each step.
“Hypothesis 1 was accepted. It seemed that the subchondral shadow of the distal tibia on the lateral radiographs was created equally by the lateral, central and medial portion of the tibial plafond,” he said.
To explore their second hypothesis, that blinded evaluators experienced in treating pilon fractures would consistently recognize displacement of 5 mm-wide osteochondral segments on lateral radiographs, investigators made three types of malreductions using a 5-mm segment. They translated it 1 cm proximally, translated and rotated it, and halved it in the coronal plane and imaged the specimens after each step.
Graves and colleagues created a PowerPoint slide show of radiographic images showing specimens without the malreductions in triplicate mixed the three malreductions. When asked on which lateral radiographs they noticed malreductions, evaluators correctly identified malreductions 45% of the time.
“There are some important implications that come out of these findings … so I think we might have to re-evaluate what we are talking about when we talk about articular reduction,” Graves said, noting the difficulty of discerning rotational and/or translational displacement of segments on perfect radiographs.
“You really need to directly visualize the articular reduction to know that you have an anatomic reduction.” — by Susan M. Rapp
Reference:
- Graves ML, Kosko JH, Barei D, et al. Lateral ankle radiographs: Do you really know what you are seeing? Paper #629. Presented at the 2010 Annual Meeting of the American Academy of Orthopaedic Surgeons. March 9-13, 2010. New Orleans.
- Matthew L. Graves, MD, can be reached at the Department of Orthopaedic Surgery and Rehabilitation, University of Mississippi Medical Center, 2500 North State St., Jackson, MS 39216; 601-815-7068; e-mail: mattgraves1@gmail.com. He is a member of the speakers bureau at and received institutional/research support from Synthes.
The authors confirmed that the fluoroscopic lateral ankle is inadequate for determining articular reduction. Their conclusion is correct with regard to evaluating the lateral fluoroscopic view in isolation. It should be recognized that fluoroscopic images are typically substandard in quality to a radiograph and that their conclusions are based on the inconsistencies of the observers’ evaluations. The observers were orthopedic surgeons experienced in pilon fractures and although experienced, they are not radiologists trained in image interpretation. It is assumed that their clinical experience is based on review of multiple views and imaging studies such that their ability to evaluate the lateral view in isolation might be limited. The authors’ conclusion that further study regarding using plain radiographs to define articular reduction as it relates to patient outcome and risk of post traumatic arthritis is valid and closer collaboration with a radiologist for these investigations might be beneficial.
– Helene Pavlov, MD,
FACR
Radiologist-in-Chief, Department of Radiology and
Imaging
Hospital for Special Surgery Professor of Radiology
Professor of
Radiology in Orthopaedic Surgery Weill Medical College of Cornell University,
New York