CONGENITAL DEFORMITY OF KNEE-JOINT AND LEG Congenital malformations of the knee are of rare occurrence. De formities of the patella arc generally found combined with other abnor malities. The patella, which is in reality simply a sesamoid bone, varies greatly in its size and shape and is dependent on the development and activity of the muscle and tendon in which it is imbedded. This is the reason we find small patelhe in cases of club-foot—due to deficient action of the muscles. Bogen describes a ease of dislocation and very small patella in one family where the mother, children, and grand children exhibited the same abnormality. The patella is exceptionally small in congenital dislocation of the knee, yet with an increase of func tion it may grow and attain its normal size.
Congenital dislocation of the patella is similar to displacement of the tendon of the quadriceps muscle.
Outward dislocation, which occurs most frequently, produces func tional disturbances in older children. There may be inability to extend the leg fully on account of the faulty action of the quadriceps muscle, which, together with the patella, appears to have slipped off the femoral pulley. This deformity is sometimes found in members of the same fam ily. The author has found heredity in six out of sixty-eight reported cases.
Therapeutic measures are necessary when the dislocation cannot be reduced, thereby preventing perfect extension of the knee and giving insufficient support to the weight of the body. In the cases of sudden dislocation which disappear spontaneously or by manual reduction, some disturbance in gait and impaired function of the joint often remain and require treatment and relief. When the dislocation is combined with marked bens valgum, the correction of the genu valgum will generally eliminate the patellar dislocation, on account of its tendency to produce secondarily such a dislocation. In other eases the capsule is doubled in on the internal side according to the method of Le Dentur or Iloffa, or, following :11i Krogius's suggestion, it loop is cut out of the external cap sular wall, drawn across the patella, and anchored in a previously pre pared fissure in the internal capsular wall. Roux performs an osteoplastic operation in very pronounced cases, grafting the insertion of the patellar tendons upon the inner surface of the tibia.
Dislocation of the knee forward (gene recurvatinn eongenitum) is the most frequent form (Fig. 52). This produces marked disturbance in the movements of the knee-joint. The action of the shortened quad riceps muscle prevents flexion when the leg is overextended. The tibia
rests on the anterior articulating surface of the eondyles and the smooth cartilaginous lining is lacking in the posterior surfaces. A tumor repre senting the projecting posterior surfaces of the condyles is palpable in the poplitcal space. The patella is generally very small and the capsule of the joint, although uninjured, is greatly distended posteriorly. The displacement of the insertions of the muscles interferes with muscular mechanism to such an extent that the flexors become extensors and increase the deformity.
From an etiological standpoint we are dealing with an embryonic anomaly in growth, which arises from pressure and fixation of the extended leg with the thigh flexed at the hip against the abdomi nal surface of the body. This condition is d tie to narrowness of the uterus, small amount of amniotic fluid, fixation by the umbilical cool or by amniotic bands. symptoms (popliteal folds) indicate that fixation even in later embryonic life is sufficient to bring about dis turbances in growth. The frequent occurrence of the deformity in one family, as well as its repeated combination with other malformations (spina bifida, disturbances of the hip, club-foot), proves that primary developmental disturbances are all fartor, :A1(110)101 inherited narrowness and lack of space may also cause further deficient develop ment.
The prognosis is favorable in so far as that there will be no further progress of the ailment. Joachimstlial has reported cases in which there had been a spontaneous in motion.
The treatment is more effective in cases seen early when apparatus can be applied to Etna the flexibility of the joint. But in most cases the tension is too great to overcome without resorting to reduction by operation. Hubscher elongates the tendon of the quadriceps muscle in the form of steps and makes a subcutaneous reposition after a ra I1S-• VerSC incision is made through the anterior capsular wall.
Congenital Deformities of the Leg.—Tolal or partial defects of both bones occur as in the forearm. They cause fixation and faulty position of the foot. For example, a defective fibula is accompanied by marked proration in the astragalus joint, and the fifth toe may be missing.
The treatment of such deformities consists in osteoplastic opera tions—substitution of the tibia by the fibula—and in some eases in the employment of prothesis.
The so-called Volkmann's deformity of the astragalus joint C011 sists of an outward distortion of the foot where both bones of the leg are intact. This is a rare occurrence.