CHAPTER XL VIII.
DISLOCATIONS OF THE ANKLE.
Surg-ical Anatomy. — The bones entering into the formation of the ankle-joint and the ligaments holding these bones in apposition, have alread}" been mentioned in the surgical anatomy- of "Pott's fracture," on page 659. The manner in whiclr the malleoli are placed on either side of the body of the astragalus explains the frequency with which fracture complicates dislocations of this ar- ticulation. Nearly all the luxations of the ankle are accompanied by fracture of either the tibia, fibula or astragalus. One or both malleoli may be broken off and displaced with the foot.
The bones of the ankle are not deeply situated and it is not uncommon to see compound luxations of the ankle. When severe and direct violence is applied to the ankle, the foot may be torn away from the tibia and tibula and displaced in any direction. The gi^eater the violence producing the injury the greater the probability of the condition being compound and complicated by fracture of the malleoli or astragalus. In severe cases the bones of the foot may be entirely torn from the lower end of the leg with only the soft tissues connecting the two, and a large rent in the skin. In such instances the character of the deformity is not typical of any of the forms of ankle luxation to be described.
The typical luxations of the ankle in their order of frecpienc}- are : outward, inward, backward, forward, and upward. It should be remembered, however, that a given luxation may present a dis- placement resembling two forms of dislocation. Thus the foot may be displaced forward and inward so that the deformity shows some of the characteristics of l30th the forward and inward types of dislocation. In many of these luxations (especially the lateral types) there may be a rotary element present in which the foot is turned either inward or outward on a more or less vertical axis. This form of displacement has been described as a separate form of luxation, and may occur as such, but is almost always secondary to one of the other dislocations just mentioned.
684
DISLOCATIONS OF THE ANKLE
685
Fig. 764. — YieM' of ligaments of foot from fibular A., Astragalus: N., Navicular; C.M., Middle cuneiform Calcaneum ; Cub., Cuboid.
side. E.M., External malleolus; C.E., External cuneiform; Gal.,
Fig. 765. — View of ligaments of foot from tibial side. Ciin.I., Internal Cuneiform: N., Navicular; A., Astragalus; T., Tibia; Cal., Calcaneum; T.I'., Tendon of tibialis posticus; (?., Groove for the passage of the tendon of the tibialis posticus.
686 FRACTURES AND DISLOCATIONS
In outivard luxations the lesions are somewhat variable. The less severe forms of this dislocation are the same as Pott's fracture, which has already been described. When the force w^hich pro- duces Pott's fracture continues to act, the lower tibio-fibular liga- ments are either ruptured, or tear away their tibial attachment, including a fragment of bone, and the astragalus continues in its outward course. If the displacement is great enough to allow the trochlear surface to clear the tibial articular surface, the astragalus will be displaced upward as well as outward and is described as one of the upw^ard luxations of the ankle (Dupuytren's disloca- tion). The more pronounced the lateral displacement of the ankle (until it clears the tibia) the greater the tendency of the astragalus to rotate on a more or less horizontal antero-posterior axis. When this rotation occurs the foot corresponds to the position assumed by the astragalus. The outer side of the foot is raised and the sole looks downward and outward. The surgical anatomy of this fracture luxation is the same as Pott's fracture (see page 659).
In inward luxations of the ankle ("inverted" or "reversed" Pott's fracture) the fibula is usually fractured at the level of the joint and the inner malleolus is broken off at its base. The line of fracture in the tibia is usually oblique, extending upward and inward from the junction of the horizontal and vertical portions of the lower tibial articular surface. The usual position of the fracture is well illustrated in Fig. 753, The astragalus commonly shows more or less rotation in a direction opposite to that usually seen in Pott's fracture. The foot is displaced inward according to the degree of causative violence. Inward rotation of the foot is particularly common in this form of luxation.
Backivard luxations are extremely rare and almost invariably accompanied by fracture. They may result from extreme plantar flexion of the foot or from a force ^hich drives the foot backward when the leg is fixed. The reverse mechanism may obtain in which the lower end of the leg is driven forward while the foot is fixed. When this type of luxation is the result of extreme plantar flexion the posterior margin of the tibia is almost invariably broken off. It is common for one or both of the malleoli to be broken off and displaced backward with the foot. The lower end of the tibia rests on the scaphoid and cuneiform bones while the astragalus is dis- placed backward. The ligaments of the joint suffer extensive laceration. If one malleolus and its corresponding lateral ligament
DISLOCATIONS OF THE ANKLE 687
remain intact the backward displacement will be accompanied by more or less of a rotary deformity with the sound malleolus as the center of the arc described.
Forward luxations are extremely rare and almost invariably accompanied by fracture of the malleoli or the anterior edge of the tibia. This type of dislocation of the ankle is produced by a force which drives the lower end of the leg backward while the foot is fixed, or the same result may follow a blow on the heel which drives the foot forward while the leg is fixed. Extreme dorsal flexion, alone or combined with an antero-posterior force, may be responsible for the luxation. When caused by flexion the anterior edge of the lower end of the tibia is almost always broken off. The reported cases of this luxation are very few, being less than fifteen in all and have usually been accompanied by fracture. Most of the uncomplicated cases were reported before the X-ray came into use and some writers question the occurrence of this luxation un- accompanied by fracture. The case shown in Fig. 768, however, is a pure luxation, as demonstrated by the X-ray plate which was taken following reduction and which showed no fracture.
Upward luxations of the ankle are extremely rare. Two forms are described. The first is simply an exaggerated Pott's fracture with diastasis of the lower tibio-fibular articulation and an upward displacement of the astragalus between the lower ends of the tibia and fibula. This luxation has already been described with out- ward dislocations of the ankle and is known as Dupuytren's lux- ation. The second form of upward dislocation is one in which the astragalus is displaced upward between the lower ends of the tibia and fibula following a diastasis of the tibio-fibular joint, without the usual complicating fracture of the fibula.
Symptoms. — In all forms of ankle luxations the pain, tenderness, loss of function and swelling are usually pronounced. Ecchymosis often develops within twelve to twenty-four hours and is much more constant if the condition is accompanied by fracture. The deformity varies with the type of luxation.
In outward luxations the appearance of the ankle is usually typical of Pott's fracture and the exaggerations of this deformity just described.
In inward luxations of the ankle, the foot is usually markedly inverted with more or less adduction. The inner side of the foot is higher than normal while the outer edge of the sole is depressed.
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FRACTURES AND DISLOCATIONS
The deformity is symmetrically opposite to that seen in Pott's frac- ture. AYhen rotary deformity accompanies the condition it is usually inward, and may be as much as ninety degrees, so the toes point directly toward the opposite foot.
Fig. 76';
Figs. 766 and 767. — Inward fracture-luxation of the ankle a few minutes follow- ing the injury. Inner malleolus broken off and displaced Avith the foot. The external malleolus remains intact. Note the prominence of the external malleolus and the way the skin is stretched betAveen it and the foot. Reduction accomplished without difficulty.
Fig. 768. — Anterior dislocation of ankle. The entire tarsus is displaced forward at the tibio-astragaloid articulation. Note the prominence of the internal malleolus in its backward displacement. Injury sustained in automobile accident. Dislocation caused by blow on posterior aspect of heel. Trauma of vulnerant body was sufficiently great to penetrate counter of shoe, without, however, injuring skin on heel. Reduction easily accomplished by pressure in bend of ankle accompanied by traction on the foot. Picture taken about two hours following accident. X-ray plate taken folloAving reduction showed no fracture.
In hacTxward dislocations the dorsum of the foot is shorter than normal and the heel is unduly prominent. The foot is usually held in a position of more or less pronounced plantar flexion as a result of the increased leverage of the muscles attached to the
DISLOCATIONS OF THE ANKLE 689
tendo Aeliillis. A transverse ridge is felt anteriorly, in the bend of the ankle, and the extensor tendons may be palpated passing across it from the leg to the foot. If the malleoli are not frac- tured they will be found displaced forward with the leg.
In forward luxations the appearance of the foot and ankle is the reverse of that just described. The dorsum of the foot is lengthened and the heel shortened. The malleoli are both dis- placed backward unless broken off. The trochlear surface of the astragalus can, as a rule, be felt in the bend of the ankle, and when the usual fracture is present it may be possible to palpate the de- tached tibial fragment.
In upward luxations accompanied by fracture of the fibula the clinical picture is that of an exaggerated Pott's fracture. Abnor- mal lateral mobilit}^ broadening of the malleoli, more or less ever- sion and crepitus are usually present on examination. The con- dition is often compound. When upward luxation exists without fracture of the fibula abnormal lateral mobility may be absent. The malleoli are lowered (nearer the sole of the foot) and widely separated. The leg above the ankle is broader than normal.
Diagnosis. — With a knowledge of the anatomy of the parts it is not difficult to recognize the different types of luxation which occur at the ankle. The presence of complicating fracture, how- ever, is often not easy to determine without the aid of the X-ray. If the case is not seen until some hours have elapsed following the injury the swelling may be so intense that palpation is quite diffi- cult. The disturbance in the alignment of the foot and leg, as viewed from the side and antero-posteriorly, should be recognized by inspection even if the swelling is pronounced. Motion of the foot will usually reveal the nature of the injury. An X-ray exam- ination of these conditions cannot be considered complete unless two plates at right angles to each other are made.
Treatment. — The nature of the injury should be appreciated by the surgeon before an attempt at reduction is made. There is usually little difficulty in returning the articular surfaces to their normal relations but when fracture complicates the condition, as it frequently does, some trouble may be experienced in maintaining reduction. A short plaster stirrup, as already described in the treatment of fractures of the tibia and fibula, is the most satisfac- tory method of treating these luxations but the application of this dressing should be delayed until the swelling (if pronounced) has
690 FRACTURES AND DISLOCATIONS
subsided. During this time the ankle may be treated in the pillow splint or fracture-box with the foot elevated and the ice cap ap- plied. If no fracture exists the most comfortable position for the foot is at an angle of about 100 degrees with the leg. In other words the foot should be immobilized in a position a little more than a right angle. If the anterior edge of the tibia has been frac- tured the foot should be fixed in plantar flexion, if the posterior edge is broken off it should be placed in dorsal flexion. In fracture of the malleoli there is usually little tendency to the recurrence of deformity if good reduction has been accomplished. In the treatment of Pott's fracture the foot is inverted as far as possible and there is no danger of overcorrecting the deformity, but in inward luxations of the ankle the reverse is not true. The deform- ity can be overcorrected and if the foot is put up in extreme ever- sion the result will be recovery with pronounced deformity. The reasons for this are apparent if we note the lines of fracture in an inward luxation as compared with a Pott's fracture. In an inward luxation the foot should be brought back into alignment with the bones of the leg and fixed with a plaster stirrup.
Operative Treatment. — Operative treatment is usually not called for except in compound luxations and in instances in which com- plicating fractures cannot be satisfactorily reduced by non-oper- ative methods. The fragment of a fractured malleolus may become displaced and wedged between the astragalus and end of the tibia, requiring removal before proper reduction can be effected. If one of the malleoli or a portion of the lower end of the tibia re- mains displaced, in spite of attempts at reduction, it may be ad- visable to fix it in position through an open incision.
Compound dislocations of the ankle should be treated along the lines laid down in the treatment of ''Compound Luxations" on page 789. The cavity of the articulation should be irrigated with a few gallons of sterile salt solution, devitalized tissue trimmed away and the wound closed. Fragments should not be wired at this time. If internal fixation is found necessary it should be per- formed at a later date after the primary wound has healed. If severe infection develops amputation may be necessary especially if the patient is old and feeble. Amputation, however, is rarely called for, even in compound cases, if proper surgical measures are carried out.
After-Treatment. — The care of these cases following reduction
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varies greatly with the complications. In simple dislocations of the ankle without fracture, ligamentous union will be firm at the end of about three weeks. Function should be resumed gradually. Gentle passive motion should be begun at the end of ten days. When the condition is complicated by fracture of the lower ends of either the tibia or fibula the after-treatment will be practically the same as that already given for "Pott's fracture" (page 673) and in "Fracture of the Lower Ends of the Tibia and Fibula."
Prognosis. — In simple luxations the prognosis is good but when fracture complicates the dislocation (as it almost invariably does) the outlook varies with the nature of the break. The prognosis is essentially that of the complicating fracture and may be considered the same as set down under "Fractures of the Lower Ends of the Tibia and Fibula," page 683, and under "Pott's Fracture," page 673.