Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Femoral Anteversion

Basics
Description
  • Femoral torsion is the angular difference between the femoral neck axis and the transcondylar axis of the knee.
  • Increased femoral anteversion can result in in-toeing.
  • Synonym: Pigeon toes
Epidemiology
  • In-toeing from increased femoral anteversion usually increases until age 5 years and then resolves by age 8 years.
  • Increased femoral anteversion is symmetric and tends to occur in females.
Incidence
Increased femoral anteversion is the most common cause of in-toeing in early childhood.
 
Risk Factors
Positive family history
 
Etiology
  • Many infants are born with a substantial amount of femoral anteversion, an external rotation contracture of the hip, and internal tibial torsion.
  • The external hip contracture initially masks increased femoral anteversion.
  • Femoral anteversion at birth is ~40°.
  • Femoral anteversion decreases until adult values (10-15°) are reached by age 8 years.
  • Differences in inheritance and connective tissue account for the variation in anteversion among patients.
Associated Conditions
Internal tibial torsion
 
Diagnosis
Signs and Symptoms
  • In-toeing and abnormal appearance of the child’s legs during walking or running
  • Parents will note that the child sits in the W or reverse-tailor position that is characteristic of patients with increased anteversion.
History
  • Tripping, shoe wear difficulty, and falling are common reasons that parents seek medical attention.
  • Knee pain is associated with increased femoral anteversion and external tibial torsion (miserable malalignment syndrome).
  • A birth history should be obtained to ascertain risk factors for cerebral palsy.
  • A family history should obtain information about rotational disorders, rickets, and skeletal dysplasias.
Physical Exam
  • Diagnosis typically can be made by physical examination.
  • Physical examination begins with inspection of the gait and progresses to an assessment from the hips to the toes.
  • Affected children run with an egg-beater-type motion.
  • In-toeing and medial-facing patellar alignment are seen during walking.
  • The rotational profile and its 5 components should be recorded.
  • The sum total of the entire extremity alignment is quantified by the foot progression angle (i.e., the angle of the foot relative to an imaginary straight line in the patient’s path).
  • Hip rotation, measured in the prone position, reflects the degree of femoral anteversion.
  • Normal hip rotation by age:
    • Infants:
      • Internal: Average, 40° (range, 10-60°)
      • External: Average, 70° (range, 45-90°)
    • By age 10 years:
      • Internal: Average, 50° (range, 25-65°)
      • External: Average, 45° (range, 25-65°)
  • Hip internal rotation of 70°, 80°, or 90° is evidence of a mild, moderate, or severe increase in femoral anteversion, respectively.
  • Increased femoral anteversion is associated with decreased hip external rotation.
  • The thigh-foot axis, in the prone position, is the angle subtended by the longitudinal axis of the thigh and the foot; this angle reflects the amount of tibial torsion present.
  • The transmalleolar axis, the angle formed at the intersection of a line between the malleoli and a line between the femoral condyles, also reflects the amount of tibial torsion.
  • The final component of the rotational profile, the heel-bisector line, identifies forefoot abduction and adduction; this line goes through the mid-axis of the hindfoot and forefoot.
  • A rotational profile 2 standard deviations outside the mean for that child’s age is considered abnormal.
Tests
Imaging
  • Radiography:
    • Are indicated in children with highly abnormal rotational profiles, short stature, marked asymmetry, or pain.
    • A pelvic radiograph is indicated if the patient has an abnormal hip examination.
  • CT may be used to quantitate the degree of femoral anteversion and for preoperative planning.
Pathological Findings
  • A progressive or asymmetric deformity suggests a possible underlying pathology and should be investigated.
  • A gait with equinus and in-toeing may suggest cerebral palsy.
  • A Trendelenburg gait or abnormal hip examination may suggest DDH.
Differential Diagnosis
  • Tibial torsion
  • Associated conditions that may lead to femoral anteversion and should be excluded:
    • DDH
    • Cerebral palsy
Treatment
General Measures
  • Pathologic processes (cerebral palsy or hip dysplasia) should be addressed.
  • Because increased femoral anteversion tends to resolve by age 8 years, no treatment is indicated for most cases.
  • Care consists of reassurance and education about the natural history.
  • Bracing and shoe modifications are unnecessary.
  • Some cases of increased femoral anteversion may persist, and remodeling after age 8 years is minimal, but most patients with persistent increased anteversion are asymptomatic.
  • Surgical intervention may be indicated in a child >8 years old with a marked functional deformity (tripping and falling during sports or activities of daily living) and femoral anteversion of >50°; careful patient selection is critical.
  • Surgery also may be indicated in children with increased femoral anteversion associated with external tibial torsion, patella alta, increased Q-angle, and anterior knee pain (miserable malalignment syndrome); again, careful patient selection is critical.
Special Therapy
Physical Therapy
Physical exercises do not affect the natural history of anteversion.
 
Surgery
  • Femoral (proximal, diaphyseal, or distal) derotation osteotomy rarely is required.
  • Fixation of a diaphyseal derotation osteotomy can be achieved with a rigid, bent nail inserted through the lateral aspect of the greater trochanter.
    • Patients may bear weight as tolerated after the procedure.
  • Derotational osteotomies of the femur and tibia may be performed for miserable malalignment syndrome.
Follow-up
Prognosis
  • Prognosis is good, and most cases resolve by age 8 years.
  • No relationship exists between increased femoral anteversion and hip arthritis.
  • No relationship exists between increased femoral anteversion and knee osteoarthritis, but decreased anteversion does place the knee at risk for osteoarthritis.
Complications
  • The potential postoperative complications of derotation osteotomy are:
    • Nonunion, malunion
    • Implant prominence
    • Overcorrection or undercorrection
    • Failure to relieve pain or other symptoms
Patient Monitoring
For patients with severe cases, annual or biannual observation and examination are recommended to document expected rotational change with growth.
 
Miscellaneous
Codes
ICD9-CM
755.63 Femoral anteversion
 
Patient Teaching
Explanation of the expected resolution and benign natural history of increased femoral anteversion
 
Activity
No limitation of activity
 
FAQ
Q: What is the natural history of increased femoral anteversion?
A: In-toeing from increased femoral anteversion usually increases until age 5 years, then resolves by age 8 years.
 
Q: How is increased femoral anteversion diagnosed?
A: By physical examination. The rotational profile shows medially directed patellae and increased hip internal rotation.
 
Q: What is the treatment for increased femoral anteversion?
A: Primarily observation. There is no role for bracing or physical therapy. In rare cases, correctional derotational osteotomy may be indicated for increased femoral anteversion that persists after age 8 years and causes functional impairment.

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