Coxa Vara: Causes, Diagnosis, and Treatment Options

• What is Coxa Vara?
• What causes this hip deformity?
• What are the symptoms?
• Diagnosis
• Complications
• Treatment and therapy for Coxa Vara
• Prevention

What is Coxa Vara?

Coxa Vara describes a hip deformity in which the angle between the femoral neck and the shaft, the long, vertical, straight part of the bone, decreases below its normal value for age, being less than 120 degrees. The condition can be congenital (present at birth) or a developmental problem that becomes apparent as a child grows.

The condition is most likely a growth disorder of the femoral neck of vascular origin in either hip, or from secondary causes related to trauma, infections, skeletal dysplasia, and pathological bone disorders.  

Coxa Vara as a congenital condition occurs in one in 25,000 births; with an increased familial incidence; it affects both sexes equally. Coxa vara occurs in rare cases at birth and, in these cases, is usually associated with other conditions, such as proximal femoral focal deficiency, fibular hemimelia (fibular aplasia), or other congenital problems.

The condition is unilateral in two-thirds of cases, more frequently affecting the left hip. Due to the condition, one leg may be shorter and can lead to a limping or waddling gait (the length difference between the two legs can be 1.5–4 cm). The condition is not evident in the child until the age of two or three.

Coxa Vara is classified into several subtypes:

• True congenital Coxa Vara - present at birth, mild or severe coxa vara, with associated congenital abnormalities. It is associated with a hypoplastic femur (especially proximally), which causes lower limb length inequality.
• Congenital Coxa Vara - associated with various congenital dysplasias such as multiple epiphyseal dysplasia, familial osteoporosis, achondroplasia.
• Infantile or developmental Coxa Vara  - appears normal at birth, then, once the child starts walking or later, the condition appears and progressively develops. This is an isolated deformity of the proximal femur. It tends to go unnoticed until the child reaches walking age, when the deformity leads to a leg length difference or an abnormal gait pattern. It usually appears between the ages of two and six, with characteristic radiographic features.
• Acquired Coxa Vara - caused by an underlying condition, such as fibrous dysplasia, rickets, or traumatic closure of the proximal femoral epiphyseal plate following a fracture of the femoral neck, secondary to tuberculosis or another systemic infection, or against the background of diseases such as osteogenesis imperfecta, cretinism, Paget's disease, or osteoporosis.

The condition can cause the femur to turn outward, and there may be problems with the knee. Hip surgery and, sometimes, femoral lengthening, are performed to improve joint movement, reduce any difference in leg length, and reduce rotation in the femur.

What causes this hip deformity?

Congenital Coxa Vara

The causes of the hip deformity in this case are associated with:

• an abnormality of the embryonic limb buds,
• dysplasia of the upper extremity of the femur,
• an intrauterine condition that causes significant proximal femoral varus.

 The condition cannot be observed clinically until childhood, as the coxa vara deformity continues to progress as the child grows.

Developmental Coxa Vara

Developmental coxa vara can occur in the context of:

• secondary metabolic, neoplastic, dysplastic, or traumatic conditions,
• the labor period in some newborns,
• childhood fractures,
• systemic infections,
• traumatic injuries to the vascular system of the hip joint that can cause ossification, which alters and stops bone growth,
• a complication of non-surgical treatment of the femoral neck.

What are the symptoms?

Symptoms of Coxa Vara  may include:

• pain in the leg and/or hip  (the condition can also be painless),
• a unilateral limp that worsens,
• stiffness when trying to move the leg sideways,
• a small difference in leg length of up to 4 cm.

Diagnosis is usually made using X-rays, and treatment will depend on the severity of the condition.

Risk factors

Risk factors that may predispose to the onset of the disease include:

• a significant family history of Coxa Vara,
• systemic infections (tuberculosis, sepsis),
• rickets, Paget's disease, osteogenesis imperfecta, cretinism, dyschondroplasia.

Diagnosis

Clinically, the condition presents as an abnormal but painless walking pattern. A slight limp is sometimes associated with unilateral coxa vara, and a waddling gait is often associated with bilateral coxa vara.

X-rays can be used to determine the Hilgenreiner angle.

Radiological diagnosis reveals a narrowing of the angle between the shaft and the neck to 90° or less, a shortened neck positioned inferiorly, a shorter, more hypotrophic, and thinner femur, and a widened growth plate positioned almost vertically.

MRI can be used to visualize the epiphyseal plate, which may be widened in coxa vara.

CT can be used to determine the degree of femoral anteversion or retroversion.

Complications

Cases of Coxa Vara requiring treatment that are left undiagnosed or untreated can lead to mobility problems later in life, difficulty moving, and will increase the risk of osteoarthritis.

Treatment and therapy for Coxa Vara

The goal of treatment is to stop the progression of Coxa Vara by speeding up the closure of the cartilage and correcting the deformities. Treatment can be orthopedic, or elective surgery.

The timing of surgery will depend on the age at which the child is diagnosed, the severity of the condition, and the treatment center. Sometimes, when a child is diagnosed at a very young age, surgery is delayed until the age of five or six. In other cases, a child may undergo surgery at around 18 months, depending on their individual circumstances.

The goal of medical interventions is to improve the hip joint, realign the epiphyseal plate to reduce shear forces, and promote ossification of the femoral neck defect. This is achieved by performing a Pauwels valgization osteotomy +/- subtrochanteric derotation - the growth plate is restored and made horizontal, and the valgus position of the femoral neck improves the action of the gluteus muscles, normalizing the cervico-diaphyseal angle, increasing the total length of the limb, and improving joint congruence.

Physical therapy is recommended once surgical correction of coxa vara has taken place and approval from the doctors has been received.

Mild cases that are treated successfully will have a reduced impact on a child into adulthood. 

Prevention

People affected by Coxa Vara must continue the home exercise therapy program provided to them at the time of discharge. The therapy is meant to maximize functional strength and mobility and minimize the risk of future injury.

Pregnant women:

• balanced diet and lifestyle,
• avoiding trauma during pregnancy,
• avoiding pregnancy in women with metabolic or neoplastic diseases.

Note! This presentation is for informational purposes only.

Conclusion

Coxa Vara is a condition that can be successfully treated in most cases by the orthopedics department, if it is diagnosed and its cause is addressed in time, and the person also follows a medical rehabilitation program.