Orthopedics - Oleksa A.P. 2006

Congenital and Acquired Deformities of the Lower Extremity
Congenital and Acquired Hip Deformities
Coxa Vara (Varus Deformity of the Femoral Neck)

The term "coxa vara" refers to a deformity of the proximal end of the Femur, characterized by a reduced neck-shaft angle—sometimes approaching a right angle—accompanied by shortening of the femoral neck.

Varus deformity of the proximal femur in children and adolescents accounts for 5–9% of all hip joint disorders (Bogdanov, F. R., 1959; Kurochkina, A. M., 1966; Revenko, T. A., & Kompaniets, A. P., 1975).

Varus deformities of the femoral neck can be either congenital or acquired.

Radiologically, at birth, the cartilaginous greater trochanters and femoral heads are not visible. Secondary ossification centers of the femoral heads appear only after 5 to 6 months. As the child grows, these centers undergo progressive ossification, and the femoral neck increases in length. This process is interconnected with the physeal Cartilage of the greater trochanters, which also gradually ossifies. The proximal end of the femur is fully formed between the fifth and eighth years of life. The neck-shaft angle, which is 150° at birth, decreases to 142°. Furthermore, physiological retroversion of the neck transitions into anteversion due to rotational growth. These physiological changes depend on the growth and position of the physis, proceeding slowly until human skeletal maturity is reached.

Congenital disorders of femoral neck ossification are caused by an abnormal, more sagittal orientation of the physeal cartilage, whereas under normal conditions, it is positioned more horizontally and perpendicularly to the axis of the neck and its load-bearing vector. This leads to varus deformity of the neck and stunted longitudinal growth.

According to Frejka, B. (1968), congenital varus deformity of the femoral neck may develop As a result of hypoplasia or impaired Development of the inferior metaphyseal vessels entering the inferior aspect of the neck region.

Ogden, J. (1984) and other researchers note that the deformity associated with coxa vara developing within the neck leads to significant disruption of the local vasculature. Inadequate arterial supply results in diminished activity and bioplasticity of the physeal cartilage, a fact already demonstrated by Delitala, F. in 1913 following histological studies.

According to Winquist and other classifications, varus deformities of the femoral neck present in various forms.

Occasionally, congenital varus deformity of the femoral neck may be associated with: 1) Femoral hypoplasia and acetabular limbus abnormalities; 2) Anomalies of the proximal femur; 3) multiple epiphyseal Dysplasia, spondylometaphyseal dysplasia, etc. (Kozlowski, K., & Napiontek, 1992; Lachman, R. S., 1988; Kabatiy, M. S., Goshko, V. Yu., 1998, among others).

Yet another group comprises acquired forms of femoral neck varus deformity: 1) post-traumatic occurring in early childhood; 2) secondary to Rickets; 3) associated with Perthes disease; 4) following congenital hip dislocation or hip dysplasia (Fig. 153), etc.

There is also a group of patients with isolated varus deformity of the neck who present no associated congenital anomalies, trauma, or Metabolic Disorders that would explain the insufficiency of the neck or growth plate abnormalities. Some authors (McDougall, A., 1961; Kozłowski, Napiontek, M., & Beim, E., 1992) suggest that coxa vara results from intrauterine trauma and the persistence of such factors postnatally. These patients show no limb shortening at birth; therefore, the Diagnosis is established only as the child's body weight increases and the structural endurance of the neck decreases, aggravating the varus deformity. This most commonly occurs when the child begins to walk (Hoyt, W. A. et al., 1984; Stevens, P. M., 1985).

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Fig. 153. Radiological view of femoral neck varus deformity resulting from hip dysplasia.

Several other classifications of femoral neck varus deformities exist. For instance, Reinberg, S. A. (1964) radiologically distinguishes four types of deformities:

1) congenital isolated varus deformity (coxa vara congenita); 2) infantile deformity (coxa vara infantilis); 3) adolescent deformity (coxa vara adolescentium); 4) symptomatic deformity (coxa vara symptomatica).

Congenital varus deformity of the neck (coxa vara congenita), occurring independently of other skeletal disorders, is universally recognized today. It is extremely rare and diagnosed immediately at birth due to visible shortening of the thigh and high positioning of the greater trochanter. In some cases, congenital hip dislocation may be suspected, necessitating additional examinations to clarify the diagnosis.

Physical examination reveals shortening of the lower extremity at the expense of the femur. The greater trochanter is palpable at a higher level than the contralateral side. The hip is weight-bearing since the femoral HEAD remains seated within the acetabulum. The diagnosis is confirmed sonographically.

When the child begins to walk, a limp appears. Subsequently, a positive Trendelenburg sign may be detected. In a one- to two-year-old child, radiographs reveal typical signs of congenital femoral neck varus deformity, where the neck is bent downward to a right angle and is somewhat shortened. The physeal cartilage lies in the sagittal plane almost vertically, while the femoral head is sometimes enlarged, rotated, and tilted downward, yet remains within the acetabulum (Fig. 154). The acetabulum appears shallow and flat when the neck-shaft angle drops below 110° (Schmidt, T. L., & Kałamchi, 1982). When this angle is corrected to 140° or more, the acetabulum develops normally. The greater trochanter lies above the level of the neck and is slightly tilted medially, increasing in size as the neck deformity progresses (Hoyt, W. et al., 1984).

Infantile varus deformity of the femoral neck (coxa vara infantilis) develops in children between the ages of three and five. Parents seek medical attention because the child has begun to limp and waddle while walking, although experiencing no pain in the limb. History-taking typically reveals that the child was born normal and had been healthy prior to onset.

Fig. 154. Radiograph of congenital coxa vara dextra: a — preoperative, b — postoperative, c — 5 years postoperatively.

Examination reveals Displacement of the greater trochanter above the Nélaton-Roser line and minor shortening of the lower extremity. Flexion and adduction of the hip are generally normal, but abduction is severely restricted. Lateral Rotation of the hip is also limited or impossible, and normal physiological hyperextension disappears.

The diagnosis is confirmed radiographically (Fig. 155). Findings include varus deformity of the neck, which is tilted downward, with a neck-shaft angle potentially as low as 90°. The physeal cartilage is located in the sagittal plane with a radiolucent zone on the neck side. Inferiorly, the cartilage appears branched due to a wedge of bone extending from the neck into it as a detached triangular fragment, with several smaller fragments at its base ("neck fragmentation"). The radiolucent cleft has an irregular shape, and the adjacent bone surfaces are jagged and mildly sclerotic (Fig. 155). It should be noted that in coxa vara, the femoral neck is never widened; rather, it progressively shortens and appears smaller due to delayed growth.

The greater trochanter is displaced superiorly and, as the varus deformity progresses, may lie several centimeters above the superior margin of the acetabulum, with the neck-shaft angle falling significantly below 90°. Consequently, the femur assumes a "shepherd's crook" appearance. The head fuses with the neck in patients aged 17–20 years; however, cases may occur where fusion fails or the head separates from the neck, resulting in upward displacement of the femur.

Fig. 155. Radiograph of infantile coxa vara.

The causes of coxa vara infantilis are considered to be (Chung S., Riser W., 1978; Nilsonne H., 1924) vascular disorders in this area and a predisposition to the disease.

When studying the Variability of the epiphyseal cartilage, Ogden emphasized the vulnerability of the Blood Vessels in the superior-posterior region of the femoral neck.

Adolescent coxa vara (coxa vara adolescentium) begins in the prepubertal period: at 14–16 years of age in boys and 10–12 years of age in girls. In nearly 30% of cases, the condition is bilateral.

Boys are affected more frequently (4:1), predominantly overweight individuals, athletes, or those engaged in heavy physical labor, whereas affected girls tend to be tall with a well-proportioned constitution (Reinberg L.S., 1968).

In the past, trauma and physical overload of the hip joint were considered the causes of the disease, though convincing evidence was lacking. Later studies put forward The Theory of hormonal disorders, as the condition is more frequently observed in adolescent males with adiposogenital features, accounting for 75% of cases (Rüther P., 1972). A decrease in the secretion of the gonadotropic hormone by the anterior Pituitary Gland was indicated by Schneider, Frejka, and others.

Unlike coxa vara infantilis, coxa vara adolescentium has a more rapid progression and is accompanied by pain that hinders patients from leading a normal life. They are forced to spare the affected leg, limp when walking, and experience only slight pain relief after rest. Examination reveals a limited range of rotational movements in the hip joint, particularly medial rotation.

The diagnosis is confirmed by radiography. In contrast to infantile coxa vara, radiographic findings in the adolescent form primarily show Changes in the region of the growth epiphyseal cartilage. In the early stages, radiography reveals only widening and softening of the enchondral zone with resorption of the adjacent spongy bone Structure OF THE neck. Subsequently, the femoral head remains within the acetabulum while rotating slightly, and the neck progressively shifts upward in a manner similar to Slipped capital femoral epiphysis, resulting in a varus deformity with an angle open downward and posteriorly. In such cases, the epiphyseal cartilage is either invisible on the anteroposterior radiograph or appears as a crescent due to the shadow of the head overlapping the displaced neck. These relationships between the neck and the head, as well as epiphyseal lucency, are clearly visible on computed tomography scans.

The femoral head retains its structure and density, whereas the pathologically altered spongy bone of the neck adjacent to the cartilage undergoes remodeling. Reactive sclerotic islands can be observed against a Background of varying bone density.

During the patient's growth, under METABOLISM/18.html">The Influence of mechanical load, a classic varus deformity of the femoral neck develops, accompanied by upward displacement of the greater trochanter and shortening of the lower extremity. The process concludes with the fusion of the head with the femoral neck (Fig. 156) within normal age-related timeframes.

Abnormal anatomical relationships in the proximal end of the femur lead to deforming arthrosis of the hip joint.

Fig. 156. Radiograph of coxa vara adolescentium complicated by osteoarthritis.

Frejka B. (1968) divides the course of the disease into four periods:

1) Osteoporosis of the femoral neck and head;

2) the period of head displacement (actually the subepiphyseal region of the neck);

3) the late period following epiphyseal displacement;

4) resolution of osteoporosis.

However, this Classification is of little clinical significance.

Thus, the mainstay in diagnosing both infantile and adolescent forms of femoral neck varus deformity is radiographic or sonographic examination, supplemented by tomographic imaging when necessary.

Depending on the stage of the disease, varus deformity sometimes needs to be differentiated from traumatic slipped capital femoral epiphysis and femoral neck fractures.

The diagnosis of slipped capital femoral epiphysis is based on Anamnesis data and is radiographically manifested by the upward displacement of the femoral neck with its anteversion at the level of the epiphyseal cartilage, while The structure of the neck remains unchanged and the normal neck-shaft angle is preserved.

Femoral neck fractures in children are extremely rare; the radiograph reveals a clear fracture line without structural changes in the spongy bone adjacent to the epiphyseal cartilage, along with a normal neck-shaft angle.

The fourth type of proximal femoral varus deformity (coxa vara symptomatica) can occur at any age. It is associated with osteodystrophies, post-rickets conditions, Osteogenesis Imperfecta, chondrodystrophy, epiphyseal and Spondyloepiphyseal Dysplasia, Bone Cysts or tumors, and even improperly healed transcervical or intertrochanteric fractures in individuals of any age. This pathological condition is rare compared to dystrophic coxa vara and represents merely a symptom of an underlying disease.

The Treatment of coxa vara has a long history. Attempts at single-stage correction of the neck axis under anesthesia—specifically neck inversion—yielded poor results and led to its damage. Furthermore, treatment via skeletal traction, closed manual reduction in plaster casts, or The Use of orthopedic devices failed to influence the disease course or prevent The Development of the neck deformity.

Considering the diminished pituitary function, Frejka B. (1968) treated patients with coxa vara adolescentium using Hormones from this endocrine gland (methylandrostenediol 1 tablet every other day, 20 tablets per course, or "Schering" gonadotropic anteron in equivalent doses) combined with calcium and vitamin D₂ supplements alongside quartz lamp irradiation. When necessary, he repeated the course of treatment and achieved favorable outcomes through limb unloading via traction.

Undoubtedly, limb unloading throughout the course of the disease is of paramount importance, yet the questions of accelerating the healing process and preventing the progression of deformity remain critical.

Weinstein J. et al. (1984) proposed a prognostic Scheme for the course of coxa vara (Fig. 157). They pointed out that when the neck-shaft angle relative to the horizontal line is less than 45°, conservative treatment is effective and spontaneous recovery is possible. Conversely, if this angle reaches 60° or more, the neck deformity will inevitably progress despite conservative treatment. An angle between 46° and 59° is essentially indeterminate from a prognostic standpoint, as the pathological process may either regress or occasionally progress under treatment, thus necessitating close clinical monitoring.

Upon diagnosing coxa vara, many orthopedists began employing surgical fixation of the femoral neck using a thin Smith-Petersen metal nail, screw, or pins inserted from the subtrochanteric region into the femoral head. Hovorth utilized bone grafts introduced via an open approach from the neck through the growth plate into the head. The use of bone grafts significantly shortened the duration of the pathological process.

In cases of severe varus deformity of the neck, attempts were made to correct its axis openly by performing a wedge resection of the neck followed by fragment fixation. However, this surgical Procedure was frequently complicated by aseptic Necrosis of the femoral head due to vascular injury and consequently failed to gain widespread acceptance among orthopedic surgeons.

Fig. 157. Schematic diagram of congenital coxa vara from a prognostic perspective: a — deformity will inevitably progress; b — spontaneous recovery is possible; c — requires careful active monitoring.

Intertrochanteric or subtrochanteric osteotomy of the femur is more commonly employed in cases of persistent deformity following the complete remodeling of the varus-deformed neck (Fig. 158). This surgical approach allows for the correction of not only the neck-shaft angle but also the femoral neck anteversion that developed during its slippage. Valgus displacement of the head should be achieved such that in children aged 5–13 years, the upper pole of the head lies above the tip of the greater trochanter: by (16±3) mm in girls and by 23±4 mm in boys (Fig. 159).

The Y-shaped osteotomy introduced by Pauwels (Pauwels F., 1936) is considered the most justified approach, as it enables deformity correction in accordance with pre-operative skiagrams and intra-operative calculations by Müller (Müller M., 1964). Stable internal fixation using a standard L-shaped plate with a 110–130° angle and a long shaft (utilizing 8–12 screws, per M.S. Kabatsiy and V.Y. Goshko, 1998) promotes rapid healing of the compromised bone. Recurrence of femoral neck varus deformity has not been observed following this procedure.

Fig. 158. Diagram of wedge intertrochanteric osteotomy of the femur.

Fig. 159. Normal level of the femoral head apex relative to the tip of the greater trochanter.