TO THE EDITOR:
The investigation performed by Thordarson et al., entitled “The Effect of Fibular Malreduction on Contact Pressures in an Ankle Fracture Malunion Model” (79-A: 1809-1815, Dec. 1997), failed to determine the effect of an isolated fibular fracture on contact pressures in the ankle joint. The model selected by the authors demonstrated the effect of a combined osseous injury of the fibula and a substantial ligamentous injury of the ankle joint. I believe that this model probably resulted in a lateral talar shift that, in effect, may be a reproduction of the talar displacement described in the previous investigation by Ramsey and Hamilton2 of the effects of lateral talar translation on contact pressures in the joint. Radiographic analysis of the specimen within the testing apparatus both before and after the loading is imperative to ascertain the alignment of the talus within the ankle mortise.
I have anxiously awaited an investigation of the effects of an isolated fibular fracture on the ankle joint. Unfortunately, the study by Thordarson et al. failed to achieve this goal, and therefore the conclusion that “displacement of the fibula in these injuries should not be accepted” is incorrect.
I hope that the authors repeat this investigation in a truly isolated fibular fracture model and add radiographic control to verify their testing design.
Paul E. Levin, M.D.: 625 Belle Terre Road, Suite 202, Port Jefferson, New York 11777
Dr. Thordarson, Dr. Motamed, Dr. Hedman, Dr. Ebramzadeh, and Dr. Bakshian reply:
We are somewhat confused by Dr. Levin's inquiry. He seems to be implying that fractures of the ankle occur as isolated osseous injuries. Beginning with the study by Lauge-Hansen1, it has been a well known phenomenon that fractures about the ankle are associated with marked rotational stress and severe ligamentous disruption. If Dr. Levin is referring to the effect of an isolated fibular fracture, then he is not referring to an ankle fracture. Although we agree with Dr. Levin that radiographs of the specimen within the testing apparatus would have provided useful information, such radiographs were not available for our study. However, the jig that we employed in our study did effect displacement of the fibula, as we described. We did not report the position of the talus, just that of the fibula. If Dr. Levin is awaiting a study evaluating the effect of an isolated fibular fracture without ligamentous injury to the ankle joint, we do not suspect that this will be performed. We would not expect noticeable changes in contact pressures in the joint in the absence of ligamentous injury as there should not be noticeable displacement if the ligaments about the ankle are intact. We disagree that our conclusion is incorrect.
David B. Thordarson, M.D.; Sohel Motamed, M.D.; Thomas Hedman, Ph.D.: Department of Orthopaedic Surgery, University of Southern California, 1200 North State Street, GNH 3900, Los Angeles, California 90033
Edward Ebramzadeh, Ph.D.: 2400 South Flower Street, Los Angeles, California 90007
Sam Bakshian, M.D.: 2921 South La Cienega Avenue, Suite A, Culver City, California 90232
1. Lauge-Hansen, N.: Fractures of the ankle. II. Combined experimental-surgical and experimental-roentgenologic investigations. Arch. Surg.
, 60: 957-985, 1950.
2. Ramsey, P. L., and Hamilton, W.: Changes in tibiotalar area of contact caused by lateral talar shift. J. Bone and Joint Surg.
, 58-A: 356-357, April 1976.