Orthopaedic Surgery - Femoral Anteversion

Basics

Femoral torsion describes the rotational relationship between the axis of the femoral neck and the transcondylar axis of the distal femur.

When the femoral neck is rotated excessively anteriorly relative to the distal femur, the condition is termed increased femoral anteversion.

Increased anteversion commonly produces in-toeing during walking or running.

In most children, the condition is benign and improves spontaneously as growth occurs.

Synonym

In-toeing caused by femoral anteversion is sometimes referred to colloquially as pigeon-toed gait, although this term can also describe other causes of in-toeing.

Epidemiology

In-toeing from increased femoral anteversion often becomes increasingly apparent during the first several years of childhood, commonly reaching its greatest visibility around 4–5 years of age.

Thereafter, spontaneous improvement usually occurs, with substantial correction by approximately 8 years of age.

Sex and Symmetry

Increased femoral anteversion is typically bilateral and relatively symmetric.

Females, on average, demonstrate somewhat greater femoral internal rotation and femoral version than males.

Incidence

Increased femoral anteversion is one of the most common causes of in-toeing in early childhood.

Risk Factors

A positive family history of rotational abnormalities increases the likelihood that a child will demonstrate increased femoral anteversion.

Etiology

Normal Development

Many newborns have substantial femoral anteversion together with an external rotation contracture of the hip and internal tibial torsion.

The external rotation contracture can initially conceal the increased femoral anteversion, so the in-toeing may not become obvious until later in childhood.

Anteversion at Birth

Femoral anteversion is approximately 40° at birth.

With normal growth and remodeling, it progressively decreases.

Adult Values

By approximately 8 years of age, much of the remodeling has occurred, with femoral anteversion approaching the typical adult range of approximately 10–15°.

Some additional variation persists among individuals.

Genetic and Connective-Tissue Factors

Differences in inheritance, connective-tissue characteristics, and skeletal development contribute to the variation in femoral rotation seen among children.

Femoral Version and Torsion

The terminology can vary.

Femoral version generally refers to the rotational orientation of the femoral neck relative to the distal femur, while femoral torsion may be used to describe rotational contribution from the femoral shaft.

The term total femoral version recognizes that both proximal and shaft anatomy contribute to the overall rotational alignment.

Associated Conditions

Increased femoral anteversion may coexist with internal tibial torsion.

The overall direction of the foot during gait reflects the combined rotational contributions of the femur, tibia, and foot.

Diagnosis

Signs and Symptoms

The characteristic presentation is in-toeing during walking or running, often accompanied by an appearance of the knees and patellae turning inward.

Most affected children have no pain.

W-Sitting

Children with increased anteversion often prefer to sit in the W position, with the hips internally rotated and the knees flexed while the feet lie outside the hips.

This position is comfortable because of their increased internal hip rotation.

Parental Concerns

Parents commonly seek evaluation because of frequent tripping, falling, unusual shoe wear, or concern about the appearance of the child’s gait.

These concerns are often most noticeable during running.

Knee Pain

Pain is uncommon in isolated childhood femoral anteversion.

Anterior knee pain may occasionally occur when excessive femoral anteversion is combined with external tibial torsion and patellofemoral malalignment, sometimes termed miserable malalignment syndrome.

History

Birth History

A birth and developmental history should be obtained.

This is particularly important when abnormal muscle tone, delayed milestones, or gait abnormalities raise concern for an underlying neurologic disorder such as cerebral palsy.

Family History

The family history should include rotational deformities, skeletal dysplasias, metabolic bone disorders such as rickets, and significant childhood gait abnormalities.

Physical Examination

General Principles

The diagnosis can usually be established clinically without advanced imaging.

Examination should begin with gait observation and then proceed systematically from the hips to the feet.

Gait

During walking, affected children demonstrate in-toeing with the patellae often pointing medially.

This helps distinguish femoral anteversion from isolated tibial or foot abnormalities.

Running Pattern

During running, the legs may demonstrate a characteristic circumduction or “eggbeater” appearance, reflecting excessive internal femoral rotation.

Rotational Profile

A complete rotational profile should be recorded when evaluating pediatric in-toeing.

This helps determine whether the deformity arises from the femur, tibia, foot, or a combination of levels.

Foot Progression Angle

The foot progression angle describes the angle between the long axis of the foot and an imaginary straight line representing the direction of walking.

A negative or inward angle reflects in-toeing, while an outward angle indicates out-toeing.

Hip Rotation

Passive internal and external rotation of the hip is an important clinical estimate of femoral rotational alignment.

The child is commonly examined prone with the knees flexed to 90°.

Hip Rotation in Infants

In infants, average internal rotation is approximately 40°, with a broad normal range of roughly 10–60°.

Average external rotation is about 70°, with a range of approximately 45–90°.

Hip Rotation by Age 10

By around 10 years of age, internal rotation averages approximately 50°, while external rotation averages about 45°, although substantial individual variation remains.

Increased Internal Rotation

Markedly increased internal rotation combined with reduced external rotation supports increased femoral anteversion.

Internal rotation approaching 70°, 80°, or 90° may correspond clinically to mild, moderate, or severe rotational excess.

External Rotation

Increased anteversion is typically associated with decreased external hip rotation.

The asymmetry between internal and external rotation is often more useful than any isolated number.

Accuracy of Clinical Examination

Clinical hip rotation measurements provide a useful estimate of femoral anteversion and correlate reasonably well with CT-based rotational measurements in many patients.

Tibial Torsion Assessment

Thigh-Foot Axis

The thigh-foot axis is measured with the patient prone and the knees flexed.

It is the angle between the longitudinal axis of the thigh and the axis of the foot.

This measurement primarily reflects tibial rotational alignment.

Transmalleolar Axis

The transmalleolar axis compares a line connecting the medial and lateral malleoli with the distal femoral condylar axis.

It provides another estimate of tibial torsion.

Foot Assessment

Heel-Bisector Line

The heel-bisector line is used to evaluate forefoot alignment.

A line is projected from the center of the heel through the forefoot to determine the presence of metatarsus adductus or abduction.

Definition of Abnormal Rotation

A rotational measurement approximately two standard deviations outside the normal mean for age is generally considered abnormal.

Clinical significance, however, depends on symptoms and functional impairment rather than measurement alone.

Imaging

General Role

Routine imaging is unnecessary for most children with typical symmetric femoral anteversion and a normal neurologic and hip examination.

Indications for Radiographs

Radiographs should be considered when there is marked asymmetry, significant pain, short stature, progressive deformity, or an unusually abnormal rotational profile.

Pelvic Radiographs

A pelvic radiograph is appropriate when the hip examination is abnormal or when developmental dysplasia of the hip or another structural hip disorder is suspected.

CT

CT can quantify femoral version accurately and may be useful in patients being considered for corrective surgery.

Because of radiation exposure, it is not routinely required for uncomplicated childhood in-toeing.

Concerning Findings

A progressive, highly asymmetric, or painful rotational deformity should prompt evaluation for underlying pathology rather than being assumed to represent physiologic femoral anteversion.

Cerebral Palsy

A gait combining equinus and in-toeing, particularly when accompanied by abnormal tone, weakness, or delayed development, may suggest cerebral palsy.

Developmental Dysplasia of the Hip

A Trendelenburg gait, restricted hip movement, limb-length inequality, or other abnormal hip findings should raise concern for developmental dysplasia of the hip.

Differential Diagnosis

Internal Tibial Torsion

Internal tibial torsion is another common cause of childhood in-toeing.

Unlike femoral anteversion, the patellae may face forward while the feet turn inward.

Developmental Dysplasia of the Hip

DDH can alter lower-extremity rotation and gait and should be excluded when the hip examination is abnormal.

Cerebral Palsy

Neuromuscular rotational abnormalities may mimic idiopathic anteversion but are usually accompanied by abnormal tone, weakness, contracture, or other neurologic findings.

Metatarsus Adductus

Forefoot adduction can also produce in-toeing and is identified through examination of the foot and heel-bisector line.

Treatment

General Principles

Most children require no active treatment because femoral anteversion improves naturally with growth.

Education and reassurance are the mainstays of management.

Natural Remodeling

Substantial spontaneous remodeling occurs before approximately 8 years of age.

After this point, further rotational correction is usually limited.

Observation

Children with a typical, symmetric deformity and no significant functional impairment can be observed.

The appearance may remain noticeable for several years even while gradual improvement is occurring.

Bracing and Shoe Modifications

Special shoes, braces, twister cables, and similar devices do not alter the natural history of femoral anteversion and are generally unnecessary.

Activity

Routine activity should not be restricted.

Most children can participate fully in sports and normal play.

Physical Therapy

Exercises and stretching do not change the underlying femoral rotation.

Physical therapy is therefore not required solely to correct idiopathic anteversion.

Therapy may be useful when another associated condition produces weakness, balance problems, or abnormal movement patterns.

Persistent Femoral Anteversion

Some children retain increased anteversion beyond 8 years of age.

Most remain asymptomatic and do not require treatment even when the rotational profile remains outside average values.

Indications for Surgery

Corrective surgery is rarely necessary.

It may be considered in a child older than approximately 8 years who has severe persistent anteversion, substantial functional impairment, and a deformity that is unlikely to remodel further.

Functional Indications

Potential indications include recurrent tripping or falling that interferes with sports or activities of daily living, marked gait dysfunction, or persistent pain clearly related to the rotational deformity.

Cosmetic appearance alone is usually insufficient.

Degree of Anteversion

Femoral anteversion greater than approximately 50° has historically been used as one factor supporting surgery when significant symptoms are also present.

The rotational measurement should never be used in isolation.

Miserable Malalignment Syndrome

Surgery may also be considered in carefully selected patients with excessive femoral anteversion combined with external tibial torsion, increased Q-angle, patella alta, and persistent anterior knee pain.

This combination is sometimes referred to as miserable malalignment syndrome.

Surgery

Femoral Derotation Osteotomy

The definitive surgical treatment is a femoral derotation osteotomy.

The femur is divided, rotated into more appropriate alignment, and stabilized with internal fixation.

Osteotomy Level

The osteotomy may be performed at the proximal femur, diaphysis, or distal femur.

No single level is ideal for every patient because excessive rotation may arise from different portions of the femur.

Preoperative planning should therefore be individualized.

Intramedullary Fixation

A diaphyseal derotation osteotomy can be stabilized with an intramedullary nail.

In adolescents, this approach can provide reliable rotational correction and may improve function and pain in carefully selected symptomatic patients.

Weight Bearing

Depending on fixation stability and surgeon preference, patients may be allowed to bear weight relatively early, sometimes as tolerated.

Combined Femoral and Tibial Osteotomy

Patients with miserable malalignment syndrome may require both femoral and tibial derotation osteotomies when clinically significant abnormalities exist at both levels.

Follow-Up

Prognosis

The prognosis is excellent.

Most children experience substantial spontaneous improvement by approximately 8 years of age and have no long-term functional limitation.

Arthritis Risk

Isolated increased femoral anteversion in otherwise healthy children has not been clearly associated with an increased risk of hip or knee osteoarthritis.

Rotational alignment at the opposite extreme, particularly decreased femoral anteversion or excessive retroversion in some settings, may have different biomechanical consequences.

Surgical Complications

Potential complications of femoral derotation osteotomy include nonunion, malunion, hardware prominence, infection, overcorrection, undercorrection, and persistence of pain or functional symptoms.

Careful patient selection is therefore essential.

Patient Monitoring

Children with mild typical femoral anteversion generally need only routine observation.

Those with severe deformity may be reviewed annually or every 6–12 months to document expected rotational improvement with growth.

Follow-up should assess gait, hip rotation, foot progression angle, functional symptoms, symmetry, pain, and the development of any findings suggesting an underlying neurologic or structural disorder.