A Method for Detection of Lateral Malleolar Malrotation Using Conventional Fluoroscopy

SLR- March 2014-James Callahan

Reference: Marmor; M. Kandemir; U. Matityahu; A. Jergesen; H. McClellan; T. and Morshed; S. A Method for Detection of Lateral Malleolar Malrotation Using Conventional Fluoroscopy. J Orthop Trauma, 27(12): e281-e284; 2013.

Scientific Literature Review

Reviewed by: James P. Callahan, DPM
Residency Program: Inova Fairfax Hospital, Falls Church, VA

Podiatric Relevance: Syndesmotic injuries of the ankle are associated with poor functional outcomes when left unrecognized or improperly treated. Reduction of the distal tibiofibular joint is imperative in restoring anatomic alignment of the ankle mortise and there by normal ankle biomechanics. Malreduction of the distal fibula is often difficult to ascertain under standard techniques and may lead to poor functional outcomes. Reproducible methods to accurately reduce the distal fibula will improve patient function and satisfaction.
 

Methods: The purpose of the study was to determine if definable radiographic criteria could better permit surgeons to detect internal and external rotation of the fibula using fluoroscopy. Three pairs of cadaveric limbs were used to simulate varying degrees of internal and external rotation of the distal fibula with a Weber C type fracture. The limbs were fixated in neutral, ten and twenty degrees of internal and external rotation and surgeons were asked to evaluate the position of the distal fibula prior to and then with the addition of the described radiographic criteria. Criteria were defined for internal rotation (IR), specifically widening of the medial clear space and spoon shaped fibula; and for external rotation (ER), tib/fib space narrowing, pointed fibula, and divergence of Shenton lines.

Results: Prior to reviewing radiographic criteria, overall accuracy in determining fibular malrotation was 43 percent, correctly detecting 20 degrees of rotation 54 percent of the time, and 10 degrees of rotation 33 percent of the time. Upon implementing radiographic criteria, overall accuracy in detecting malrotation increased to 67 percent, detecting 20 degrees of deformity improved to 83 percent, and assessing 10 degrees of malrotation improved to 54 percent.

Conclusions: Known malreduction of the distal fibula has lead to poor functional outcomes and as few as 5-15 degrees of ER has shown increased contact pressure across the ankle joint. In addition to observing the radiographic parameters described, obtaining a mortise view of the contralateral ankle is recommended to improve radiographic alignment, as a true reference to a “neutral” ankle. Increased awareness of the reviewed radiographic markers will aid the foot and ankle surgeon in pre-operative planning, intra-operative execution and most importantly, improved postoperative outcomes.