Fracture.docx

FRACTURE-DISLOCATION OF THE ANKLE WITH FIXED DISPLACEMENT OF THE FIBULA BEHIND THE TIBIA In the past eighteen months, five eases of fracture-dislocation of the ankle joint have been seen, in which satisfactory reduction could not be accomplished by closed methods. On open exposure, a situation was found which, to the author's knowledge, has not previously been reported. It is probable that many other such eases occur, and that bad results ensue, due to lack of knowledge of the basic mechanical situation. The first patient was seen in December 1944. Roentgenograms showed a typical bimalleolar fracture, with marked displacement. On attempted closed reduction, Fig. 1-A : Faulty reduction, secured in fracture-dislocation of the ankle when the upper fibular fragment was caught behind the tibia. Fig. 1-B : Fig. 1-C : talus beneath tibia.

Original roentgenogram of fracture-dislocation of the ankle. Lateral view. Following attempt at closed reduction, shows faulty position of

Fig. 1-D : Postoperative reduction. After fibula had been pried from behnd tibia and the fragment had been fastened with serews.

Poor reposition of the talus beneath the tibia was secured, and even this could not be maintained (Figs. 1-A and 1-C). An open exploration was done, and even at operation it was impossible to determine at first why reduction could not be secured. Upon further extension of the incision, it was found that the proximal portion of the fibula had been dosplaced behind the ribia and was caught in back of the posterolateral ridge of the tibia. The fibula was held in this position by the tight stres of the interosseous membrane above. A pry was inserted betweeen the tibia and fibula; and, with considerable force, the fibula was pried out from in back of the tibia and moved into its proper place with a loud snap. Reduction of the fracture-dislocation was then secured easily. In February 1945, Henry Briggin, M.D., called about a patient with fracture-dislocation of the ankle in whom the fibula alone was involved. He had attempted to do two reductions by aid of the fluoroscope within half an hour of the time of injury, but was unable to replace the talus satisfactorily beneath the tibia. Indeed, when he had obtained the reduction as nearly possible, the blood supply to the rest of the foot was lacking. A diagnosis was immediately made of posterior fixation of the fibula behind the tibia; and at operation, a few hours later, this situation was found to be present. The fibula was pried out from its displaced location, and the talus could easily be replaced beneath the tibia border (Figs. 2-A, 2-B, and 2-C). In both of these instanees, metal fixation of the fractured malleoli was done.

Fig. 2-A : Fracture-dislocation of the ankle before reduction, with fibula caught behind posterolateral ridge on tibia. Fig. 2-B : Showing the best closed reduction that could be secured. At the time these roentgenograms were taken, the foot circulation was shut off by mechanical pressure of the fibula against the posterior vessels. Fig. 2-C : Reduction has been obtained by open operation, use of a pry, and fixation of the lateral malleolus with a screw. Fig. 3-A : Original reduction of fracture-dislocation of the ankle, with fibula caught behind tibia. Roentgenograms show incomplete reposition of talus beneath tibia. Fig. 3-B : Result of fifth attempt at closed reduction. Faulty reposition of talus under tibia and widened ankle mortise are shown. Fig. 3-C : Final result in a fracture-dislocation of the ankle, with fibula caught behind tibia. Attempt at closed reduction was unsatisfactory. Solid malunion was present before ankle fusion was done. The third case was seen at ehe Mary Fleteher Hospital in Burlington, Vermont. The patient appeared with the typical clinical findings of malunion of a fracture-dislocation of the ankle, which involved the lateral malleolus alone. Roentgenograms showed incomplete reduction of the talus benath the tibia and the typical findings of posterior displacement of the upper fragment of the fibula behing the tibia, although to the casual observer the fibula did not appear so dosplaced (Figs. 3-A, 3-B, and 3-C). Reduction had been done on November 17 and December 1, 1944; two reductions were done on December 3; and an attempt at re-reduction was made on December 11. In desperation, the surgeon finally accepted the bad situation. The east was still in place when the patient was firt see by the author, four months later. Arthrodesis of the ankle joint was done for disability and relief of pain. From this, one can see the importance of recognizing the occasional case with posterior displacement of th fibula behind the tibia. Two other simial cases of fracture-dislocation of the ankle, with posterior fixation of the fibula behind the tibia, have been seen. One patient, a woman, continued under conservative care, with the talus dispaleed laterally under the tibia, for two years. The malleoli became united with the tibia and fibula, buat traumatic arthritic changes occurred in the ankle joint and pain persisted. Two years after the fracture, the patient was seen by the author and ankle fusion was performed. A police offieer,who was seen nine months after injury, had union of the fibular fracture and widening of the tibial mortise. A diagnosis was made of posterior fixation of the fibula behind the tibia, at operation, the diagnosis was confirmed. The widening of the tibial mortise could not be overcome even with the lateral malleolus separated entirely from the fibula above and from all other structures except the collateral ligament until the proximal fragment had been displaced from behind the tibia and returned to its normal location. This was apparently due to the traction attachment of soft tissue from the talus and calcaneus to the proximal fragment of the fibula.since the patient was an active and youthful person. Reconstruction of the ankle mortise was attemped by simple fixtation of the fibular fragments with screws. Six months after the operation, this patient

returned to light police duty and has no demonstrable defects in or about the region of his damaged ankle. The author belevies that the situation described ariscs as follows, as the foot twists under the talus, with the leg continuing to push forward and to rotate outward, the lateral collateral ligaments draw the intact fibula behind the tibia. Continuation of the force rotating the talus beckward and out from its position bencath the tibia causes further force on the lateral collateral ligaments, finally, the fibula is broken off against the posterior tibial border, as one would break a bone over a wedge in doing an osteoclasis. Following the fracture and the cessation of the forces , there is nothing left attached to the upper fragment of the fibula by wich it can be drawn back into place. One may tear off the periosteum and swing the talus under, or nearly under, the tibia . it is impossible, however, to force the upper fibular fragment back around the posterolateral ridge on the lower tibia. Because of the tight pull of the still intact interosscous membrane. Only by insertion of a pry between the two bones will enough leverage be produced to replace the fibula in its proper location on the lateral surface of the tibia. Upon inserting such a pry. One will find that it passes transversely between the two bones instead of in an anteroposterior direction, because of the displaced osseous structures, a great amount of force in necessary for replacement, even with pry. The reason all such fractures do not have the upper fragment of the fibula impacted behind the tibia is that , in most of them, the fibula breaks off(due to leverage against the lateral surface of the tibia) before it has been swung backward over the posterolateral tibial ridge. The interosscous membrane is undoubtedly too tough and tight in most instances to allow displacement of the fibula to occur before the fracture takes place. Photographs and roentgenograms of an articulated specimen of a tibia and fibula show that, on the lateral view in normal position the tibia and fibula become superimposed and he almost in the same straight line (fig 4-a). it has always been felt, in interpreting roentgenograms, that the fibula would be at a posterior level, because the medial malleolus is anterior to the lateral malleolus .this is not so,since the medial malleolus really arises from the front half of the medial surface of the tibia. When the fibula is slightly displaced and caught behind the posterolateral ridge only (fig 4-B). on the anteroposterior view it appears to be in its normal position on the lateral surface of the tibia. The lateral views, both in the photograps and the roentgenograms, show that the fibula is truly caught behind the lateral ridge of the distal portion of the tibia. Oftentimes roengenograms are interpreted as showing no displacement of this upper fibular fragment, because it is believed by the roentgenologist that the view taken was not truly lateral or

FRACTURE-DISLOCATION OF THE ANKLE 135 truly anteroposterior. In the badly displaced upper fibular fragment (Fig. 4-C) , there should be no difficulty in interpreting the roentgenograms properly, if the roentgenologist understands that posterior fixation of the fibula behind the tibia can occur in fracturedislocation of the ankle. Actually, the interpretation is generally wrong, because the possibility of such a situation has not occurred to the roentgenologist. Having these facts in mind, if one reviews the roentgenograms for the first there cases presented here, it will be noted in each instance that gross discrepancies appear in the roentgenograms, pathognomonic of posterior dislocation of the fibula behind the tibia, and that in no preoperative roentgenogram shown was the fibula clearly seen to be in its normal relationsihip to the tibia.

SUMMARY In fracture-dislocation of the ankle, one should make sure that the upper fragment of the fibula is not caught behind the posterolateral ridge of the tibia. In some instances, fracture of the lateral malleolus does not occur until the foot has twisted beneath the ankle joint, drawing the fibula behind the tibia and breaking it off against the posterior margin there of. When this occurs, the fibula is firmly caught and needs open reduction with a pry; severe disability is likely to occur unless accurate replacement is made by operative means. DISCUSSION DR. R. I. HARRIS, TORONTO, ONTARIO, CANADA: A recent experience, fresh my memory, is clarified by Dr. Boswortlm’s presentation. It can best be presented by illustrations. Figure 1-A shows the fracturedislocation sustained by a farmer, forty-seven years old. In Figure 1-B is seen the result obtained by manipulations. Figure 1-C shows the best result which could be obtained by repeated manipulations. Open operation was undertaken. The lower end of the upper fibular fragnment was deeply buried behind the tibia. It was fixed firmly in this position, and strongly resisted replacement. Unlike Dr. Boswortim, ı did not detect time true state of affairs. Strong leverage finally shifted the fragment, which then suddenly snapped back into something like its normal position. It was secured to the lower fragment by a suture of stainlaıs-steel wire. The result of the operation is shown in Figure 1-D. I now recognize that this difficult fracture problem was of the type described by Dr. Boswortlm. It is well timat it simould be recorded, for I feel certain timat imis observations will explain imitherto unsatisfactory