Coxa vara is a

deformity A deformity, dysmorphism, or dysmorphic feature is a major abnormality of an organism that makes a part of the body appear or function differently than how it is supposed to. Causes Deformity can be caused by a variety of factors: *Arthritis a ...

of the hip, whereby the angle between the head and the shaft of the

femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...

is reduced to less than 120 degrees. This results in the leg being shortened and the development of a limp. It may be

congenital A birth defect is an abnormal condition that is present at childbirth, birth, regardless of its cause. Birth defects may result in disability, disabilities that may be physical disability, physical, intellectual disability, intellectual, or dev ...

and is commonly caused by

injury Injury is physiological damage to the living tissue of any organism, whether in humans, in other animals, or in plants. Injuries can be caused in many ways, including mechanically with penetration by sharp objects such as teeth or with ...

, such as a

fracture Fracture is the appearance of a crack or complete separation of an object or material into two or more pieces under the action of stress (mechanics), stress. The fracture of a solid usually occurs due to the development of certain displacemen ...

. It can also occur when the

bone tissue A bone is a Stiffness, rigid Organ (biology), organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red blood cell, red and white blood cells, store minerals, provi ...

in the neck of the femur is softer than normal, causing it to bend under the weight of the body. This may either be congenital or the result of a bone disorder. The most common cause of coxa vara is either congenital or developmental. Other common causes include metabolic bone diseases (e.g.

Paget's disease of bone Paget's disease of bone (commonly known as Paget's disease or, historically, osteitis deformans) is a condition involving Bone remodeling, cellular remodeling and deformity of one or more bones. The affected bones show signs of dysregulated bone ...

), post-Perthes deformity,

osteomyelitis Osteomyelitis (OM) is the infectious inflammation of bone marrow. Symptoms may include pain in a specific bone with overlying redness, fever, and weakness. The feet, spine, and hips are the most commonly involved bones in adults. The cause is ...

, and post traumatic (due to improper healing of a fracture between the greater and

lesser trochanter In human anatomy, the lesser trochanter is a conical, posteromedial, bony projection from the shaft of the femur. It serves as the principal insertion site of the iliopsoas muscle. Structure The lesser trochanter is a conical posteromedial p ...

). Shepherd's Crook deformity is a severe form of coxa vara where the proximal femur is severely deformed with a reduction in the neck shaft angle beyond 90 degrees. It is most commonly a sequela of

osteogenesis imperfecta Osteogenesis imperfecta (; OI), colloquially known as brittle bone disease, is a group of genetic disorders that all result in bones that bone fracture, break easily. The range of symptoms—on the skeleton as well as on the body's other Or ...

, Paget's disease, osteomyelitis,

tumour A neoplasm () is a type of abnormal and excessive growth of tissue (biology), tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tiss ...

and tumour-like conditions (e.g.

fibrous dysplasia Fibrous dysplasia is a very rare nonhereditary genetic disorder where normal bone and marrow is replaced with fibrous tissue, resulting in formation of bone that is weak and prone to expansion. As a result, most complications result from fract ...

). Coxa vara can happen in

cleidocranial dysostosis Cleidocranial dysostosis (CCD), also called cleidocranial dysplasia, is a congenital disorder, birth defect that mostly affects the bones and teeth. The collarbones are typically either poorly developed or absent, which allows the shoulders to be ...

Anatomy

In early skeletal development, a common physis serves the greater trochanter and the capital femoral epiphysis. This physis divides as growth continues in a balance that favors the capital epiphysis and creates a normal neck shaft angle (angle between the femoral shaft and the neck). The corresponding angle at maturity is 135 ± 7 degrees. Another angle used for the measurement of coxa vara is the cervicofemoral angle which is approximately 35 degrees at infancy and increases to 45 degrees after maturity.

Types

Developmental

* primary defect in endochondral ossification of the medial part of the femoral neck (Most common cause) * Excessive interuterine pressure on the developing fetal hip * vascular insult * Faulty maturation of the cartilage and metaphyseal bone of the femoral neck Clinical feature: presents after the child has started walking but before six years of age. Usually associated with a painless hip due to mild abductor weakness and mild limb length discrepancy. If there is a bilateral involvement the child might have a waddling gait or trendelenburg gait with an increased lumbar lordosis. The greater trochanter is usually prominent on palpation and is more proximal. Restricted abduction and internal rotation. X-ray: decreased neck shaft angle, increased cervicofemoral angle, vertical physis, shortened femoral neck decrease in femoral anteversion. HE angle (Hilgenriener epiphyseal angle- angle subtended between a horizontal line connecting the

triradiate cartilage The triradiate cartilage (in Latin cartilago ypsiloformis) is the Y-shaped epiphyseal plate between the ilium, ischium and pubis to form the acetabulum of the os coxae. Human development In children, the triradiate cartilage closes at an appr ...

and the epiphysis); normal angle is <30 degrees. Treatment: HE angle of 45–60 degrees: observation and periodic follow up. Indication for surgery: HE angle more than 60 degrees, progressive deformity, neck-shaft angle <90 degrees, development of Trendelenburg gait Surgery: subtrochanteric valgus osteotomy with adequate internal rotation of distal fragment to correct anteversion; common complication is recurrence. If HE angle is reduced to 38 degrees, less evidence of recurrence; post operative spica cast is used for a period of 6–8 weeks. Coxa vara is also seen in Niemann–Pick disease.

Congenital

Presence at birth is extremely rare and associated with other congenital anomalies such as proximal femoral focal deficiency, fibular hemimelia or anomalies in other part of the body such as cleidocranial dyastosis. The femoral deformity is present in the subtrochanteric area where the bone is bent. The cortices are thickened and may be associated with overlying skin dimples. External rotation of the femur with valgus deformity of knee may be noted. This condition does not resolve and requires surgical management. Surgical management includes valgus osteotomy to improve hip biomechanics and length and rotational osteotomy to correct retroversion and lengthening.

References

* S.Swischuk, S.John: Differential Diagnosis in Pediatric Radiology, Williams & Wilkins 1995, * D Resnick: Diagnosis of Bone and Joint Disorders Vol V, Saunders 1995,

External links