Commentary on
"Overtightening of the Ankle Syndesmosis:Is It Really Possible?"
By Paul Tornetta III, MD et al.

Commentary by Robert W. Bucholz, MD*,
The University of Texas Health Science Center, Dallas, TX

No single issue in the management of ankle fractures stimulates more controversy than syndesmosis fixation. Opinions vary widely on when, where, and how the distal tibiofibular syndesmosis should be surgically stabilized. Even if there is consensus on the need for fixation, technical details such as the location, number, length, insertion method, and eventual removal of syndesmosis screws are debated. One procedural principle which hitherto had not been challenged is the necessity of dorsiflexing the ankle during screw-tightening to avoid mediolateral narrowing of the plafond.

Dr. Tornetta and colleagues have performed a simple experiment in cadavers to measure the effect of ankle position during syndesmosis fixation on ankle dorsiflexion after the procedure. Their hypothesis was that compression of the syndesmosis with the ankle in plantar flexion would not restrict ankle dorsiflexion.

The results of any cadaveric biomechanical or radiographic study are valid only in so far as the testing design replicates clinical conditions. While the authors of this study controlled the most important variables which might affect their results, several details of their experimental design may be flawed. First, no fracture or osteotomy of the fibula proximal to the syndesmosis was created (to simulate a Weber C fracture). Depending on the location and stability of such a fracture, the placement of a syndesmosis screw may compress or distract the syndesmosis and alter the dimensions of the plafond. The position of the ankle at the time of screw compression may or may not affect these results. Second, the distance of the syndesmosis screw from the plafond was unclear. The distance should have been standardized to eliminate any unrecognized effect of screw location on plafond compression. Third, the results may have been different if there was a fracture that was shortened or malaligned above the syndesmosis screw. When syndesmosis screws are inserted without concomitant anatomic reduction of the fibula, subtle shortening and rotatory malalignment, as shown by Yablon¹are common. With such nonanatomic alignment of the lateral malleolus, the effect of syndesmosis screw-fixation may be altered. Thus, the results of this study may be valid only in the presence of an intact, non-fractured lateral malleolus.

Loss of ankle motion is predictable after all malleolar fracture/dislocations, regardless of whether anatomic reduction is achieved. In a randomized study of 155 closed, displaced malleolar fractures, we compared the radiographic and functional results of metallic screws with those of bioabsorbable screws². We reported an average loss of 3 to 4° of dorsiflexion and 10 to 12° of plantar flexion at a three-year follow-up, irrespective of the type of fixation used or the quality of reduction. Loss of ankle motion can be attributed to periarticular scarring of ligaments and the capsule, malreduction, associated injuries and/or prolonged immobilization. Knowing this natural history of malleolar fractures that have been treated by acceptable surgical techniques makes it easy to understand why clinical confirmation of the results of this cadaveric study is not feasible. There are too many variables influencing the ultimate range of ankle motion to isolate the effect, if any, of ankle position at the time of syndesmosis compression. Nevertheless, this study clearly has value. I will feel better the next time that I forget to dorsiflex the ankle during syndesmosis fixation, now knowing that I probably have done no harm to my patient.

*The author did not receive grants or outside funding in support of his research or preparation of this manuscript. He did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the author is affiliated or associated.

References

1. Yablon IG, Leach RE. Reconstruction of malunited fractures of the lateral malleolus. J. Bone Joint Surg Am. 1989;71:521-7.
2. Bucholz RW, Henry S, Henley MB. Fixation with bioabsorbable screws for the treatment of fractures of the ankle. J Bone Joint Surg Am. 1994;76:319-24.

Related Reading
Olerud C, Molander H. Bi- and trimalleolar ankle fractures operated with nonrigid internal fixation. Clin Orthop. 1986;206:253-60.
Kaye RA. Stabilization of ankle syndesmosis injuries with a syndesmosis screw. Foot Ankle. 1989;9:290-3.