Congenital Dislocation Of The Patella Associated With Congenital Short Tibia And Fibula, And Partial Adactylia

Chestley L. Yelton, M.D.


It is comparatively rare for a patella to be dislocated at birth and never occupy a normal position unless placed in this position surgically. In reviewing the English literature we were unable to find any reports of a case with this condition combined with congenital short tibia and fibula, and partial adactylia. The case being reported here has been followed in the Birmingham Child Amputee Clinic for more than 20 years.

Case Presentation

V.R., a white female, was born on June 12, 1948, and was first seen in the Crippled Children's Clinic at the age of three and one-third months at which time she was described as having a congenital hypoplastic anomaly of the right foot. A longitudinal deficiency of the foot was noted with an adactylia of the first and second metatarsals and an aphalangia of the third toe. The hind foot appeared to be normal. As the foot was in some equinus and would not come up to a right angle at the ankle, a series of casts was applied to bring the foot into some dorsiflexion, after which a long-leg brace with a right-angle stop was applied. At the age of two years it was noted that the right leg was one-half inch shorter than the left and that the right knee continued to "buckle" when unsupported. The patella could be felt lying over the lateral condyle of the femur. No femoral shortening was apparent and the pelvis and hips appeared to be normal on roentgenographic examination.

The Early Bracing

A long-leg brace with drop locks at the knee and an equinus stop at the ankle was applied to the child's right shoe to which a buildup of three-eighths of an inch was added. At the age of three years and ten months, the ossification center for the patella had not appeared but the result of an X-ray examination of the right knee was reported as "negative for bone pathology." The patella could be palpated and, as in the earlier examination, it was lying over the lateral femoral condyle. Passively, the knee could be extended fully and, when extended, the patella could be pushed forward so that it would lie anterior to the lateral femoral condyle if a medial pressure was applied continually. It could not be pushed as far as the anterior midline. Once the pressure was removed, the patella would slip back into a lateral position. The patient continued wearing a long-leg brace and a buildup on her shoe. Longitudinal growth of the femora continued to be equal but, as she grew older, leg length inequality increased with all of the shortening occurring below the right knee.

Shoe Buildup Increased

At the age of 14 years, the right foot was in equinus (Fig. 1 ) and the girl was wearing an unsightly shoe which had been built up on the inside to allow her to walk with the foot in an equinus position. In addition to the inside buildup, a buildup of three and one-half inches was added to the heel. Even with the inside and outside buildups, she still stood with a slight pelvic tilt to the right.

Exposure to PTB Prostheses

V.N. was invited to visit the Amputee Clinic so that she might have an opportunity to observe other girls wearing PTB prostheses. This she did and she developed a desire to be able to wear such a prosthesis in the future. She was advised that, in order to wear a limb of this type, it would be necessary for her to be able to actively extend her leg and that surgery would be required to make this possible. Her parents had been and were refractory to any type of surgery but they finally acquiesced and in July of 1964, when the patient was 16 years of age, surgery was performed. Roentgenograms of the right knee just prior to surgery are seen in Fig. 2 . It is rare to find a patella as dislocated as is seen here.

Knee Surgery

At surgery it was found that the lateral femoral condyle was somewhat undeveloped, its anterior projection was less than normal and the intercondylar groove was extremely shallow anteriorly. In addition, the vastus internus was very poorly developed. A transplantation of the semitendinosus tendon to the patella combined with a lateral capsular release, medial capsular reefing, creation of an intercondylar groove for articulation with the patella and transplantation of the tibial tubercle and patellar tendon to a more distal and medial position on the tibia using intrinsic internal fixation as described by McKeever 1,2, was carried out. We could not advance the tendon far enough distally to bring the patella down into a normal position. Roentgenograms of the knee 18 months following surgery are shown in Fig. 3 . The limb was immobilized in a light long leg cast for three weeks with the knee flexed to 15 degrees. The girl was placed on quadriceps exercises and soon redeveloped this muscle group to where the knee no longer "buckled" and her lack of confidence in the knee disappeared.

Amputation and Prosthesis

Beginning in July of 1966, she was followed in the Amputee Clinic and was promised that we would convert her to an amputee when her parents consented or when she became of age. Finally she obtained her parents' consent and in July of 1968, at the age of 20, a below-the-knee amputation was carried out with a six-inch below-knee stump being obtained. Roentgenograms of the right ankle and foot taken three months prior to the amputation are shown in Fig. 4 and Fig. 5 . Because of the displaced bone ends, no consideration was given to a Syme's amputation. In Fig. 6 , the right and left legs are shown just prior to surgery for purposes of comparison. At this time the leg length discrepancy was approximately six inches.

As there was not much muscle mass below the knee, shrinkage was soon obtained and a prosthesis was prescribed. Because of some lateral knee instability, she was fitted with a Patellar-Tendon-Bearing Supracondylar prosthesis which is seen from the front and side in Fig. 7 . Today she is walking extremely well without any obvious limp. She is comfortable in the prosthesis and very pleased with the improvement in cosmesis.

Summary

An instance of lower limb deficiency, which combined partial adactylia T/3:1,2, according to the Frantz and O'Rahilly classifications system3, with congenital short tibia and fibula and congenital dislocation of the patella,is reported. No redislocation of the patella has occurred in the four and one-half years since the dislocation was surgically corrected.

Chestley L. Yelton, M.D. is associated with Birmingham Child Amputee Clinic Birmingham, Alabama

References:
1. McKeever, D.C.: "Recurrent Dislocation of the Patella," Clin. Orthop., 3:55-60, 1954. 
2. McKeever, D.C.: "Transplantation of the Tibial Tubercle," J. Bone and Joint Surg., 43-A:478-479, Apr. 1951. 
3. Frantz, C.H., and O'Rahilly, R.: "Congenital Skeletal Limb Deficiencies," J. Bone and Joint Surg., 43-A: 1202-1224, Dec. 1961.