SLR - May 2014 - Mieasha Hicks
Reference: Marmor M, Kandemir U, Matityahu A, Jergesen H, McClellan T, Morshed S. J Orthop Trauma; 27(12);e281-e284:2013.
Scientific Literature Review
Reviewed By: Mieasha Hicks, DPM
Residency Program: Grant Medical Center, Columbus, Ohio
Podiatric Relevance: Within the realm of ankle fractures, it is not uncommon for rotational deformities to be missed with standard radiographic parameters. Malreductions of the fibula may go undetected, leading to poor functional outcomes postoperatively. The authors in this study developed a new set of radiographic criteria to help detect distal fibular internal and external rotation using conventional fluoroscopy. This new criteria helps to improve the accuracy and agreement on direction of fibula rotation.
Methods: This is a cadaveric study utilizing three pairs of fresh-frozen cadaveric specimens. Each model had simulated Weber C fractures. The proximal fibula and tibia were fixed to jigs, with a rotation arm attached to the distal fibula. The rotating arm was connected to a distal dial mechanism capable of measuring rotation to within one degree of accuracy. Fluoroscopy generated CT cuts at the level of the syndesmosis were used to further verify the rotation of the distal fibula within the incisura. C-arm fluoroscopy with 3-D rotational x-ray capabilities were used to obtain anteroposterior, mortise and lateral radiographic views as well as fluoroscopically generated CT cuts. Mortise views were prepared on slides for the right side consisting of 0 degree, 10 degree internal and external rotation, 20 degree internal and external rotation and the contralateral neutral ankle view. Two orthopedic surgeons analyzed whether the distal fibula was fixed in internal rotation, external rotation or similar to the contralateral side. At first they were asked to evaluate without knowing the criteria and then asked to repeat their evaluation knowing the criteria.
Results: Before knowing the criteria overall accuracy for detecting fibular malrotation and its direction was 43 percent. The accuracy for detecting 20 degrees of internal or external rotation was 54 percent, and detecting 10 degrees of internal or external rotation was 33 percent. After learning the radiographic criteria overall accuracy for detecting fibular malrotation was 67 percent. Accuracy of detecting 20 degrees of internal or external rotation and detecting 10 degrees of internal or external rotation were 83 percent and 54 percent respectively. Overall, radiographic criteria sensitivity for detecting any rotation was 0.73.
Conclusion: This study has shown that rotational malreduction of the distal fibula can be accurately detected using standard fluoroscopy for rotational deformities as little as 10 to 20 degrees. This new suggested criteria shows improvement in the accuracy and clinically acceptable intraobserver agreement. And although the clinical significance of detecting malrotation was not evaluated in this study, other studies have shown that a significant increase in contact pressures of tibiotalar joint occur with external rotation of the fibula at 5 to 15 degrees. With that said the authors believe that any simple tool that can improve accuracy of reduction warrants consideration.