Congenital Hypoplasia of the Tibia with Deficiency of the Distal Tibial Epiphysis
Leslie C. Meyer, M.D.
The various morphological patterns in meromelia of the lower extremity make classification difficult, particularly when some of the related epiphyseal deficiencies are studied. This report presents two cases involving the distal tibial epiphysis and the ankle joint in the hypoplastic tibia. No attempt is made to present these cases as rare or different, although a preliminary search of the literature shows no large number of cases described and no great experience in regard to their management1,3,6,7,8,9. The classification of limb-deficient children presented by Frantz and O'Rahilly4 and the modification of their classification by the Subcommittee on Child Prosthetics Problems as reported by Burtch2 do not elaborate on this problem.
Henkel and Willert5 in evaluating and classifying their patients found disturbances in the skeletal maturation of bones not directly involved in the defect. The disturbance is most marked at the very end of the bone where the adjacent metaphysis is affected by the defect. This has been shown as a retardation of cartilaginous ossification. These authors found bony structures appearing which were not present in early childhood, indicating delayed ossification. Histological study of these cartilaginous masses located near the long bones have demonstrated that they are capable of late ossification. In addition, it has been noted that in the humerus and femur delayed ossification can often be expected in the region of the head and neck, whereas in the radius and tibia it occurs at the very distal end of the defect zone.
In the two cases presented here a deficiency of the ossification centers in the hypoplastic tibia resulted in a deformity of the ankle. Neither of these cases presented a significant deformity of the foot except for some hypoplasia of the first ray. This digit appeared to be normal in its configuration, but smaller in size.
Case No. 1-D.E.H. (S. H. #9675) was born Apr. 16, 1961. A Caucasian male, he was admitted to Shriners Hospital at the age of 5 1/2 months with a diagnosis of clubfoot on the right limb which had been treated with an exercise program. No other abnormalities were noted. The right ankle demonstrated a marked enlargement of the medial malleolus with a mild varus deformity of the forefoot which was freely movable and correctable. The heel cord was not tight.
X-rays revealed an incomplete development or hypoplasia of the lateral portion of the distal tibia (Fig. 1 ). The fibular segment appeared to be normal but slightly enlarged. An associated proximal displacement of the talus with spreading of the distal tibiofibular articulation was evident. There was 1.5 cm. of shortening of the right tibia in comparison with the left.
During ambulation the talus slipped upward between the medial and lateral segments of the tibia and fibula causing ankle joint instability.
On Sept. 28, 1962, an osteotomy at the midshaft of the right fibula was carried out with transplantation of the right distal fibular segment into the tibia to create a surgical synostosis (Fig. 2 ).
Partial excision of the prominent right distal medial tibial epiphysis was done on July 16, 1965 (Fig. 3 ).
On February 17, 1972, epiphysiodeses were performed on the proximal left tibia and fibula and the right proximal fibula.
The surgical synostosis increased the stability of the ankle with a definite increase in size of the distal fibular segment as soon as it began to take more stress. The synostosis prevented the spreading of the two bones distally thereby adding to their stability. As the child developed, a rather poor distal tibial epiphysis began to form. With continued weight-bearing the distal tibial and fibular segments began to conform to the adjacent talus to give some semblance of a normal ankle joint (Fig. 4 ).
An arthrogram revealed separate-joint cavities for the tibia and fibula. A leg-length discrepancy of 4.3 cm., all occurring in the tibia, was corrected by proximal left tibial and fibular epiphysiodeses. The overgrowth of the proximal fibula on the right is being corrected by a proximal fibular epiphysiodesis.
Yelton9 in a detailed description of a single case showed an x-ray almost identical to that of this patient. However, in his case the limb was deleted because of excessive shortening.
While it is possible that this patient may ultimately require an ankle arthrodesis, at present the contour of this ankle is quite satisfactory, and he walks without difficulty (Fig. 5 ).
Case No. 2-E.D.C. (S H. #9052) was born on Jan. 1, 1949. A Negro female, this child was admitted at the age of 19 months with congenital deformities of all four extremities: (1) Meromelia, terminal, longitudinal, metacarpal I, left; (2) Meromelia, intercalary, longitudinal, metacarpal I, right; (3) Meromelia, intercalary, longitudinal, tibia, right and meromelia, intercalary, longitudinal, metatarsal I, right, P and M; (4) Hypoplasia right femur; (5) Tibial hypoplasia, left, with malformation of the distal tibial epiphysis (Fig. 6 and FIg. 7 ).
This patient had numerous surgical procedures: (1) Lengthening of the tendo Achillis, posterior tibial tendon, flexor hallucis longus, flexor digitorum longus, right; (2) posterior capsulotomy ankle and lengthening of tendo Achillis, left; (3) transplantation of the patellar tendon to the fibula, right; (4) arthrodesis fibula to femur, right; (5) osteotomy tarsal bones right with ankle arthrodesis; (6) pollicization of the right thumb; (7) growth arrest, distal femoral epiphysis, left; and proximal tibial and fibular epiphysis, left; (8) osteotomy of the tarsal bones, right.
The problem under consideration in this girl is the hypoplastic right tibia with malformation of the distal epiphysis and the associated clubfoot deformity. No abnormality of the tarsus or metatarsals was evident. There was overgrowth of the medial aspect of the tibia (medial malleolus) with its own epiphysis (Fig. 8 ). Definite failure of normal longitudinal growth in this tibia was evident although it could not be measured accurately because of shortening on the opposite side. However, approximately 2 cm. of overgrowth of the fibula proximally was noted. The ankle of this child had a surprisingly normal appearance and she was able to walk satisfactorily without discomfort (Fig. 9 ).
The patient was lost to follow-up at the age of 13 years. On her last visit, deletion of the right foot was advised to convert her to a prosthetic wearer because of the excessive shortening of the right lower extremity. After growth was complete, it was planned to excise the excessively long medial segment of the tibia (medial malleolus) on the left limb. Ankle fusion was to be considered only if the ankle became painful.
These two patients showed two different morphological patterns in the distal tibial epiphysis of a hypoplastic tibia. Initially, at the age of approximately 18 months, the two patients showed rather similar patterns of the distal tibia and ankle joint on x-ray. In watching these two children develop it was apparent that all patients with hypoplastic tibiae should be treated conservatively until the distal tibial epiphysis makes its appearance. This is particularly true if the foot is satisfactory and any leg-length discrepancy present is not in excess of what can be corrected by growth-arrest procedures.
Shriners Hospital for Crippled Children Greenville, South Carolina
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