CHAPTER XL.
FRACTURES AND LUXATIONS OF THE SEMILUNAR CARTILAGES.
Surgical Anatomy. — The semilunar cartilages are two crescentic masses interposed between the articular surfaces of the tibia and femur and serve to deepen the articular surfaces on the head of the tibia. The superficial margins are thick, correspond roughly with the outline of the upper end of the tibia and are attached to the deep surface of the capsule of the knee-joint. The central margins of these cartilages are thin and lie free in the joint. Be- tween the articular surfaces of the tibia we have attached from before backward : the anterior end of the internal semilunar carti- lage, the anterior crucial ligament, the anterior end of the external cartilage, the posterior end of the same cartilage and, lastly, the posterior crucial ligament. It will be seen from this, that the two extremities of the external cartilage practically meet at the spine of the tibia while the extremities of the internal cartilage are separated by a considerable distance. The deep structure of these cartilages is fibrous while the surface is composed of hyaline carti- lage. They are triangular on cross-section. The circumference of each cartilage is bound to the borders of the tuberosities of the tibia by the capsule of the joint, which is continuous on the outer and inner aspects of the articulation with the lateral ligaments. The portion of the capsule thus attaching the cartilages to the tibia is known as the coronary ligaments, and fibres stretching between the anterior convexity of the two cartilages has been described as the transverse ligament. The knee-joint is of the hinge type with complimentary gliding and rotary motion. In extension, lateral motion is prevented by the lateral ligaments, but in flexion this function is performed by the crucial ligaments. The angle at which the tibia joins the femur in extension, normally throws greater strain on the internal lateral ligament than on the external. The internal cartilage is much more intimately attached to the in- ternal lateral ligament than is the external to the external lateral
587
588 , FRACTURES AND DISLOCATIONS
ligament. Rupture and displacement of the internal lateral liga- ment will therefore be much more likely to disturb the internal cartilage than would be the case with the external cartilage if the external ligament were injured. The normal lateral angle of the knee is such that the longitudinal stress produced by the weight of the body tends to separate the articular surfaces on the inner side of the joint. The circumference of the cartilage is attached to the internal lateral ligament and when this structure is torn the carti- lage may be displaced inward and jammed between the articular surfaces. When the femur is displaced laterally on the tibia the condyles ride upward on the semilunar cartilages and thus serve to bring the crucial ligaments to a tension. In sprains of the knee the semilunar cartilages may be fractured or displaced. They may be found free in the joint or only partially detached. A portion of the cartilage may be fractured and partially or completely separated from the remainder. It may be folded upon itself and in cases of long standing various degenerative changes have been noted in the entire joint as well as in the cartilage. Cases are on record in which the cartilage from one side of the articulation has been found on the opposite side of the joint cavity.
Symptoms. — In the typical case the clinical picture is quite characteristic. The patient gives a history of having been taken with severe pain in the knee (usually on the inner side) while the joint was partly flexed and under strain. The joint locked, so that he was unable to extend the leg, though it may have been possible for him to hobble some distance Avith the knee in a position about half way between complete extension and semiflexion. By repeated attempts at flexion and extension or with medical aid something was felt to give within the joint and the knee was again found to be free and capable of full extension.
Following the accident evidences of traumatic arthritis develop and the patient is confined to the house for a period varying from a few days to a few weeks according to the severity of the reaction. It is during this time that the surgeon usually first sees the case. If the patient gets about as soon as the swelling subsides recurrence of the accident is almost sure to occur when the knee is subjected to similar strain and position. The reaction following subsequent luxations is usually less severe than that attending the first dis- placement. In the atypical case there may be no history of the knee having locked. The patient may complain only of a sense of
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589
insecurity in the joint and of pain under strain, at times. In old cases the only evidences of the condition may be found in secondary changes such as chronic hypertrophic arthritis. For a number of days following the accident it is the rule to find tenderness in the region of the cartilage, usually the internal, and in some instances
Fig. 656. — Subluxation of the knee Avitli later;ri disluratiuu i.l the patella. The in- ternal lateral ligaments are torn and the semilunar cartilage displaced toward the spine of the tibia.
Fig. 657. — ^Another view of the same case showing between the tibia and femur.
how the finger may be inserted
a gap between the bones may be produced by manipulation. Pain may be referred to the patella rather than the region of the carti- lage though the tenderness is always more pronounced at the site of the cartilage. The absence of physical signs, however, is char- acteristic following the traumatic reaction. When the condition
590 . FRACTURES AND DISLOCATIONS
becomes recurrent it is not infrequently quite disabling. The time consumed in recovering from the traumatic reaction and the sense of insecurity which the patient experiences during the intervals are important sources of disability. The fact that the knee may be thrown out of function at any time deters him from many ac- tivities. The degenerative changes which so often follow in the articulation are important.
Diagnosis. — With the typical history of sudden pain and "lock- ing" of the joint, with complete release of the articulation when the cartilage is reduced, the diagnosis is easy. In atypical cases, however, without the characteristic symptoms of locking of the knee, it may be impossible to arrive at a diagnosis until the joint is explored. It might seem that a diagnosis should be made in all cases, yet experience will show that mistakes are common even among those most thoroughly versed in the internal derangements of the knee. When the case is not typical the condition must be differentiated from : dislocations of the patella, synovial fringes, joint mice, lipomata and subluxations of the knee.
If the patient is seen daring the acute disability there will be little difficulty in differentiating lesions of the semilunar cartilages from luxations of the patella. If, however, we are obliged to rely on the history given by the patient it may become an extremely difficult matter to arrive at a diagnosis. If the patella has been dislocated the region of the knee cap will be tender for a few days following the displacement and it is often possible, especially under anesthesia, to displace the bone beyond its normal limits. More- over the characteristic tenderness on the inner side of the knee at the site of the semilunar cartilage is absent. If the case is seen some weeks or months following the accident it may be impossible to determine the conditions that existed, if the patient gives the usual imperfect history. When synovial fringes are pinched, the locking is not as pronounced and solid as occurs in luxations of the semilunar cartilages. IMoreover the point at which the motion of the knee is interfered with is not constant and the pain is usually more intense and acute than occurs when the semilunar is at fault. When joint mice are present it may be possible to palpate one or more of the loose bodies within the articulation, and the point at which the action of the knee is interfered with varies with different attacks. If the disturbance in function is due to lipomata the acute symptoms are less severe and the subsequent acute traumatic ar-
FRACTURES AND LUXATIONS OF SEMILUNAR CARTILAGES 591
thritis is usually negligible. In addition a permanent puffiness is usually noted on either side of the patellar ligament which repre- sents the enlarged fat pad beneath the ligament. In subluxations of the knee the history of trauma and the abnormal mobility will usually clear the diagnosis. The joint cavities have been injected with hydrogen and the X-ray used to determine the outlines of the semilunar cartilages but this method of diagnosis is seldom indi- cated in general practice. When it is employed the dangers of infecting the articulation should be kept in mind. In chronic dis- turbances of the knee the important points to be determined are whether or not the disturbance in function is sufficient to warrant opening the knee and whether or not good functional results can be obtained without operation.
Treatment. — If the case is seen while the cartilage is luxated, reduction should be effected at once. Reduction of the displaced cartilage is usually easy though cases are occasionally encountered in which open incision is necessary. Reduction is effected by acute flexion of the knee, the leg is then rotated back and forth on its axis and laterally deviated from side to side and finally extended. In acute flexion of the knee the most convex portions of the femoral condyles are in contact with the articular surfaces of the tibia and accordingly there is more room for the cartilages than when the knee is extended. This accounts for the release of the pinched cartilage during acute flexion. The rocking and rotary motions just described also tend to free the cartilage. If the surgeon flexes the knee over his wrist, the latter acts as a fulcrum and aids ma- terially in separating the articular surfaces of the femur and tibia. If these manipulations have been successful and the cartilage has been freed, complete and active extension of the knee will be pos- sible and painless. If they have failed the knee, will be blocked just short of full extension and the patient will be unable to hold the leg extended in the horizontal position. Moreover the attempt will be attended by pain. The proof of reduction is the free active extension of the joint unattended by pain. The patient will almost invariably be able to state when the cartilage is reduced. His con- duct reminds one of luxations of the shoulder in which the sufferer exclaims with satisfaction as the head of the bone slips back into the glenoid. The care of the case following reduction will be taken up in the after-treatment.
Operative Treatment. — The indications for operative treatment
592 FRACTURES AND DISLOCATIONS
var}^ with the social state of the patient and the nature of the lesion. If this luxation occurs for the first time in a gentleman of leisure, who has ample time for non-operative methods and can avoid subsequent strain to the joint, the condition may be treated expectantly. If on the other hand the patient is a laboring man, whose time and activity mean his living, the cartilage causing the trouble should be removed at once. The advisability of operating following the first luxation is a question. If reduction is accom- plished and the joint immobilized for a period sufficiently long to allow complete healing of the ligaments and cartilage, the condition may not recur. Cases of habitual luxation, with or without evi- dences of degenerative changes within the joint, call for operative intervention. Nothing can be expected from non-operative meth- ods under these circumstances.
A vertical incision is made beginning about one inch behind the lateral border of the patella and a little above the horizontal plane of the articulation. This is carried downward across the articu- lation and continued backward in a curved direction as soon as the scalpel comes opposite the tuberosity of the tibia. After the skin incision is made the cutaneous edges are covered with gauze, which is held in position by tenaculse. The tissues are then divided down to the capsule of the joint, which is incised with the least possible trauma. The half of the joint cavity to be operated upon is then open for inspection and the nature of the lesion may be determined. The most rigid asepsis sliould he ohserved; the gloved fingers should not be introduced within the articulation and instruments having come in contact with the hands should not enter the cavity. Sponges should be used but once. If the cartilage is fractured, detached (partially or completely), folded upon itself or degen- erated it should be removed. Anchoring of the cartilage to prevent luxation should not be attempted as the results are not satisfactory. Removal of the cartilage should be accomplished with as little trauma as possible. If other derangements are encountered within the articulation they should be corrected. Following operation the joint should be immobilized and an ice cap applied to the knee to control any traumatic arthritis which may develop.
After-Treatment. — The care of the case following non-operative reduction consists in immobilizing the knee on a posterior splint in complete extension. Elevation of the lower extremity and the use of the ice cap will tend to control the traumatic reaction. If trau-
FRACTURES AND LUXATIONS OF SEMILUNAR CARTILAGES 593
matic arthritis develops Buck's extension should be employed. Immobilization should be maintained for a period of three weeks and the resumption of function should be gradual. Strain to the knee in the flexed or semi-flexed position should be avoided for three or four months. If the inner side of the sole of the shoe is built up and the patient forms the habit of "toeing in" in walking, much of the strain will be removed from the internal lateral liga- ment and thus the chances of recurrent luxations of the internal semilunar will be reduced. Following operation and removal of the cartilage motion may be begun at the end of ten days and the patient may return to w^ork within two weeks if there are no com- plications.
Prognosis.^ — Fracture or dislocation of a semilunar cartilage may occur only once if proj^er immobilization has been carried out fol- lowing the accident. If on the other hand function is resumed immediately or as soon as the traumatic arthritis has subsided, re- currence is almost sure to follow. Restoration of function fol- lowing operation is prompt and complete. The patient is able to resume his original occupation or to follow the sport in which the injury was sustained.