Orthopedics - Oleksa A.P. 2006

Congenital and acquired deformities of the lower limb
Congenital deformities of the lower leg
Congenital pseudarthrosis of the tibia

Congenital pseudarthrosis of the Tibia is extremely rare (according to Boychev (1968), more than 400 cases have been described in the literature). Some authors consider it a consequence of tibial bowing (Reinberg S.A., 1968), while others view it as a distinct clinical entity (sui generis) caused by mesenchymal hypoplasia, i.e., an intrauterine fetal malformation. Codevilla points to an embryonic vascular defect of the lower leg, confirmed by angiographic data; Borellini notes the absence of the a.tibialis anterior, and Bochi points to generalized vascular hypoplasia of the lower leg. The cause of pseudarthrosis is believed to be an intrauterine fracture, localized Osteogenesis Imperfecta, amniotic bands, etc. Reinberg interprets this defect as an intrauterine bone remodeling of the Fibrous Dysplasia type of neurotropic origin.

Clinically, pseudarthrosis of the lower leg presents with the following signs: a typical deformity — crus antecurvatum, pathological stiff mobility at the apex of the deformity (at the junction of the middle and lower thirds of the tibia) accompanied by limb hypotrophy (Fig. 180, a).

At birth, these signs are subtle, so parents often do not notice the pathology. As the child begins to stand and walk, the deformity of the lower leg gradually worsens, accompanied by the appearance of pathological mobility at the apex of the deformity. Children experience no pain, bear weight on the limb, and quickly adapt to the defect. Due to the angular deformity of the lower leg bones, gradual shortening of the triceps surae Muscle and the Achilles tendon occurs. The FOOT is in hyperextension relative to the distal segment of the lower leg. Due to the limb shortening, children limp, the pelvis tilts, the spine curves, and static deformities develop in the joints adjacent to the pseudarthrosis.

Radiologically, bone changes typical of congenital pseudarthrosis are revealed, although they vary in severity (Fig. 180, b). Characteristically, the pathological process is localized in the tibial diaphysis at the junction of the middle and lower thirds, and sometimes in the Fibula as well. We treated a 10-year-old boy who presented with typical angular deformity of the left lower leg with pathologically stiff and painless mobility. The radiograph revealed congenital pseudarthrosis with tapered (icicle-like) ends of the two tibial segments and a diastasis of about 3 mm between them. The fibula was intact and slightly curved in two planes (varus and antecurvation).

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Fig. 180. Congenital pseudarthrosis of both BONES OF THE lower leg: a - clinical view, b - radiographic view.

S.A. Reinberg (1964), describing pseudarthrosis of the lower leg bones, points out that this disease is "non-standard" and has variations. A child may be born with only a typical angular deformity of the lower leg bones, and as weight-bearing on the limb increases, bone remodeling occurs at the apex of the deformity, characterized by cystic lucencies and rarefaction, followed by an incomplete or complete fracture.

Reinberg believes that this defect is a congenital deformity of the lower leg, a congenital angulation, and at most, it should be called "so-called pseudarthrosis." He provides radiographic data to support his interpretation.

Radiologists and clinicians distinguish three forms of congenital pseudarthrosis.

The first form is stiff pseudarthrosis, characterized by slight arcuate bowing and shortening of the lower leg, with radiographically sclerotic ends of the pseudarthrosis. The fibula is intact. This condition is identified after birth and attempts at conservative Treatment.

The second form is mobile pseudarthrosis, in which the ends of the bone fragments are tapered, atrophic, and form a significant angular deformity of the limb segment. Concurrently, pseudarthrosis of the fibula may occur. According to B. Boychev (1968), this form most commonly originates prenatally.

The third form is pseudarthrosis with a significant loss of bone mass, representing a partial ectromelia. The bone ends are sclerotic, with diastasis between them. A pseudarthrosis is always present at the same level in the fibula.

Treatment. Although conservative treatment of congenital pseudarthrosis of the tibia is ineffective, it should still be used in all cases until the child is old enough for surgery. As mentioned, bowing of the lower leg at the level of the pseudarthrosis progresses once the child begins to bear weight on the limb. Therefore, during this period, it is crucial to prevent severe deformity and disruption of anatomical relationships within the segment.

These children undergo muscle massage, manual correction, and are prescribed a corrective thin plastic splint in which they can walk.

The timing of surgery remains controversial because very often, despite bone grafting, the tibial fragments fail to unite, leading to a recurrence of the pseudarthrosis. This can be explained by the low reparative potential of the Bone tissue and periosteum, as well as impaired local Blood supply. It was previously believed that pediatric patients should not undergo surgery before 4–5 years of age, and some even suggested delaying surgery until after Puberty. We believe that the age of 4–5 years is optimal for Surgical treatment.

We operated on the 10-year-old boy mentioned above. The surgical Procedure was as follows: The pseudarthrosis site of the tibia was exposed via a linear incision. Dense scar tissue was removed from around and between the sharp tibial fragments. On one side, the cortical layer of both fragments was decorticated to accommodate a bone allograft, and the medullary canals were opened. An osteotomy was performed at the apex of the fibular curvature, and the axis of the lower leg was aligned with some difficulty, without lengthening the Achilles tendon. This eliminated the existing diastasis between the fragments. The bone graft was perfectly fitted to the decorticated surfaces of the tibia and secured with two wire cerclage sutures. The wounds were closed, and a long leg plaster cast extending to the middle third of the thigh was applied, as we did not yet have the Ilizarov apparatus at that time.

Three months later, the knee was freed, and the patient was discharged home (to a Romani family in a neighboring region) with a recommendation to return for a follow-up examination in three months. The boy arrived on his own, unattended, a year and a half later. The antecurvation of the lower leg was minimal, and no significant pathological changes were visible. The radiograph revealed a typical pseudarthrosis of the tibia in the form of a very narrow transverse cleft, but with flat, wide ends of the fragments, because the graft had achieved bony union and remodeled, but was fractured or resorbed in the middle. It was impossible to determine how long the lower leg had remained in the plaster cast and when the patient had started bearing weight on the leg. After prolonged walking, the boy experienced pain in his leg, which prompted him to return for a follow-up visit.

Fig. 181. Diagram of the staged treatment of congenital pseudarthrosis of the lower leg bones using the G.A. Ilizarov apparatus method.

Considering the width of the fragment ends and the narrow transverse cleft of the pseudarthrosis, it was decided to perform a fibular osteotomy, apply a four-ring Ilizarov apparatus, and stabilize the tibia after applying some compression. Bone union was achieved after 7 months.

We believe that today the optimal method for treating congenital pseudarthrosis of the tibia is bone grafting combined with stable fixation using the Ilizarov apparatus. During treatment, It is important to monitor the tension of the wires and, if necessary, enhance stability by adjusting them on the rods. The apparatus must not be remo

ved until bony union of the tibial fragments is achieved. In the event of an inflammatory process around a wire, one should not wait for suppuration to develop, but rather reposition the wire in a timely manner.

The attempt to transfer a fibular graft on a vascular pedicle was successful (Fig. 181).

Historical operations (Fig. 182) such as the Hahn-Huntington (a), Putti (b), and Lexer-Khakhutov (c) Procedures are no longer performed. Attempts at tibial osteosynthesis by driving a Küntscher nail from the SOLE OF THE foot through the calcaneus and talus were also ineffective without bone grafting. Today, orthopedists resect the sharp ends of the tibia at the pseudarthrosis site and reconstruct the defect using a gradually developing distraction regenerate according to Ilizarov after performing a bone osteotomy in the proximal metaphysis.

Fig. 182. Operations for congenital pseudarthrosis of the lower leg bones: a - Hahn-Huntington, b - Putti, c - Lexer-Khakhutov.