Joint dislocation

Dislocations. A dislocation is a displacement from each other of the articular ends of the bones which enter into the formation of a joint. A diagnosis can usually be made from certain objective and subjective symptoms, taken in conjunction with an accurate history of the manner in which the accident occurred.

Examination should be made in a systematic manner in every case, us follows:

(1) Inspection. The limb should be first inspected to note the position, the alterations of contour, or of the axis of the limb, or the projection or absence of certain bony prominences. The position is often so characteristic that a diagnosis can be made by inspection alone.

(2) Palpation. By this one can learn the relation of the displaced articular ends to each other, unless the swelling is too great, or the patient is very stout. This method also enables one to ascertain the absence of normal prominences or the presence of abnormal ones. The end of the displaced bone may be felt in an abnormal position.

(3) Measurement. The limb may only appear to be or is actually shortened. In the latter event the normal measurements between bony prominences will be altered.

(4) A skiagraph  should be made in all doubtful cases to confirm the diagnosis of dislocation, and also to ascertain whether there is an accompanying fracture.

When the patient is stout, or when considerable swelling exists the use of the X-ray is of especial value.

The attitude of the limb is often so characteristic that simple inspection will enable one to make a diagnosis by this means alone. In stout persons, a change in the axis of the limb or a change in position is apt to be overlooked. The relation of the articular surfaces can be determined by palpation, unless the swelling is too great. Measurement of the limb will usually show a shortening, depending upon the position in which the limb is held. The movements of a dislocated joint are usually limited. If any movement of the end of one of the bones is felt, it is always at an abnormal point. Pain is referred to the dislocated joint and the patient is unable to use the limb.

Treatment. As a rule, a dislocation should be reduced as soon as the diagnosis is made, and, if necessary, an anesthetic should be administered.

When reduction has been accomplished, the bone often goes back with a snap, the contour of the limb is restored, and the movements of the joint are free again.

If it is impossible to reduce a recent dislocation, the following obstacles must be considered: (a ) interposed portions of the capsule; (b ) interposed muscles or tendons or sesamoid bones; (c ) torn off fragments of bone; (d ) a fracture of the shaft close to its articular end, which would prevent its being used as a lever for reduction.

The after-treatment of a dislocation is usually quite simple. A bandage or splint should be applied, which will keep the joint immobilized for a period of two weeks, after which passive motion and massage can be begun for fifteen minutes twice daily, the splint or bandage then to be reapplied for another two weeks.

Dislocations at the Ankle Joint

Backward Dislocations  occur more frequently than those in a forward direction.

The injury usually is the result of a fall backward while the foot is flexed. This causes an extreme plantar flexion of the foot. The astragalus, and with it the foot, is displaced backward. The lateral ligaments are usually extensively torn. In the majority of cases there is an accompanying fracture of either one or both malleoli or of the shaft of the fibula.

Diagnosis. The front portion of the foot is shortened while the heel is more prominent than normal. The lower end of the tibia protrudes over the dorsum of the foot and the sharp edge of its articular surface can be distinctly felt. The extensor tendons and the tendo Achillis are tense and prominent. It may be distinguished from a supramalleolar fracture by the fact that the malleoli in the latter have moved backward with the foot, while in a dislocation backward they are prominent at some distance in front of the heel.

Treatment. Reduction is usually effected by forced plantar flexion, the foot being pulled forward and the lower end of the tibia being pushed backward. These steps are then followed by dorsal flexion of the foot.

After reduction, the leg should be immobilized for three weeks in a molded posterior splint. Light passive motion can be begun during the fourth week. In old unreduced cases an arthrotomy is indicated.

Forward Dislocations. These are much rarer than the backward form. They are usually due to a forced dorsal flexion of the foot. This form is less often accompanied by a fracture of the malleoli than is the case in the backward dislocation. The fibula is seldom broken, the usual seat of the fracture being in the tip of the internal malleolus or in the articular surface of the tibia.

Diagnosis. The whole foot appears to be lengthened. The prominence due to the heel has disappeared; the upper articular surface of the astragalus can be felt, the tibia and the malleoli being nearer to the heel.

The condition can be differentiated from a fracture of both bones of the leg above the malleoli by the fact that in a forward dislocation the malleoli are further back than normal, while in a supramalleolar fracture they have moved forward with the foot.

Treatment. Reduction is readily effected by marked dorsal flexion of the foot, pressure being made in a forward direction upon the lower end of the tibia, and the foot pushed backward. Plantar flexion now completes the reduction. The after treatment is the same as in the backward form.

Lateral Dislocations. The other forms of dislocations seen in the ankle are those in a lateral direction, either inward or outward. The diagnosis is usually easy. The upper convex surface of the astragalus is directed toward the external malleolus and can be felt there. The inner border of the foot is raised; the outer rests upon the bed.

This form of dislocation is very frequently a compound one, or it is accompanied by fractures of the bones of the leg or of the astragalus; but it may occur without these injuries.

Treatment. The treatment of these lateral dislocations differs but little from that of fractures of the lower end of the tibia and fibula. Reduction is effected by adduction or abduction of the foot. The chief danger is from infection on account of the extensive injury of the skin and soft parts. If reduction is impossible, perform an arthrotomy.

Subastragaloid Dislocation. Two forms of dislocation can occur in the joint between the astragalus and the two tarsal bones (os calcis and scaphoid) with which it articulates. In the true subastragaloid form, the astragalus continues to articulate with the tibia and fibula, but it is displaced from its articulation with the os calcis and scaphoid. In the second form of subastragaloid dislocation, the astragalus is completely separated from its articulation with the bones of the leg as well as with the calcaneus and scaphoid. To this form the name total dislocation of the astragalus is given.

True Subastragaloid Dislocations. These dislocations may occur in four directions, inward, outward, forward, and backward.

Dislocation inward. The most frequent cause is a forcible adduction of the foot combined with violence acting in the direction of the long axis of the foot. The diagnosis can be made from the position of the foot. The foot is adducted and rotated inward, as in a case of clubfoot. The sole of the foot is directed inward. The inner edge of the foot is concave and shortened while the outer edge appears lengthened. The external malleolus and head of the astragalus are very prominent on the outer side of the foot. Below and behind the inner malleolus the scaphoid projects beneath the skin.

Dislocation Outward. This occurs after forced adduction of the foot. The symptoms are the opposite of those of the inward variety. The foot is in the position of a flat foot, its inner edge depressed and outer edge raised. The inner malleolus is close to the sole of the foot, and in front of it the head of the astragalus forms a prominence. The injury is not infrequently compound, so that the astragalus presents into the wound.

Dislocation Backward. The cause is usually a plantar flexion of the foot. The signs are very pronounced; the head of the astragalus can be seen and felt lying upon the upper surface of the scaphoid and cuneiform bones. The anterior portion of the foot is shortened while the heel is lengthened and the tendo Achillis is very prominent.

Dislocation Forward. This follows forced dorsal flexion of the foot, the patient falling forward after landing with his heels upon the ground. The diagnosis can be made because of the lengthened anterior portion of the foot and the shortened heel. An important point in the diagnosis of subastragaloid dislocation is the absence of any prominence due to the projection of the body of the astragalus, in front, behind, or to either side of the malleoli, as is seen in the case of the tibiotarsal dislocations. A second diagnostic point is the abnormal position of the calcaneus and scaphoid with relation to the malleoli and astragalus. The swelling is usually so great that a diagnosis is very difficult without the use of the X-ray.

Treatment of Subastragaloid Dislocations. Reduction can usually be effected in recent cases by manipulation and traction. In the inward variety the existing adduction is at first increased. Pressure is now made over the outer side of the adduction and the inner side of the foot, and the foot is then strongly abducted. In the outward variety, the abduction is first increased. Pressure is then made over the outer side of the foot until reduction is effected. In the backward variety, the plantar flexion is first increased and the foot is then strongly flexed in the opposite direction. In the forward type, forced dorsal flexion will effect reduction. The foot should be placed upon a posterior molded splint for three weeks, after which passive motions are begun. If the reduction is impossible, an arthrotomy with excision of the astragalus may be necessary.

Total Dislocation of the Astragalus. This form of dislocation is much more frequent than those of the ankle joint proper, or of the articulation between the astragalus, calcaneus, and scaphoid. The displacement of the astragalus may occur in one of six directions: forward; outward and forward; inward and forward; inward; backward, and by rotation.

The most frequent variety is the “outward and forward.” In this variety the foot is rotated markedly inward and the external malleolus is very prominent. The foot is in a clubfoot position. The dislocated astragalus can be felt as an irregular angular bone just below the external malleolus.

Treatment  is the same as in subastragaloid dislocations.

Dislocation of the Metatarsal Bones. This may be either complete or incomplete at Lisfranc's joint. It occurs most often in an upward direction. The dorsum of the foot is more convex than normal, while the sole of the foot is flattened. One can see and feel the displaced ends (upper) of the metatarsals on the dorsum of the foot. The foot is shortened and the toes point inward.

Dislocations of the individual metatarsal bones are much rarer. The middle ones are displaced upward, and the first and fifth, inward and outward respectively.

Dislocation of the Toes. This occurs most often in the metatarsophalangeal joint of the great toe after forcible flexion. The dislocation may be complete or incomplete. In the former case, the proximal end of the first phalanx and the dorsum of the foot are prominent, and the head of the metatarsal bone projects on the sole of the foot. The reduction of toe dislocations presents no difficulties.