What are Bow Legs?

Definition of Bow Legs:

Anatomy Overview:

The primary skeletal anatomy involves the lower extremity, including the femur (thigh bone), tibia, and fibula (shin bones). The bow-legged condition consists of abduction of the hip joint, a folding inward at the knee joint (adduction), and inversion of the ankle joint. While bow legs are primarily a frontal plane deviation, this typically is accompanied by knee hyperextension and internal or external rotation of the lower leg that involve movements in the sagittal and transverse planes.

The boney landmarks observed in the postural assessment of bow legs include the hip, knee, and ankle joints. Examination of these areas indicates the degree of varus (outward angulation) present.

Synonymous Posture Terms:

• Genu varum
• Varus knees
• Varus stress
• Bow-legged
• Bow-leggedness
• Bowed legs
• Bowing of the legs
• Bowlegs

The Biomechanics of Bow Legs

Skeletal and Muscular Structures:

In bow legs, the muscles on the outside (lateral side) of the legs vary in length based on which joint or joints they cross. The lateral hip muscles, for instance, typically become shortened and tight as the hip joint abducts. In contrast, the muscles on the hips' inside (medial side) may be lengthened and weak with the same hip joint abduction.

Specific muscles, such as the biceps femoris (part of the hamstrings), may be shortened or lengthened depending on the rotation of the knee and relative extension or flexion of the knee. Focusing on the frontal plane motions of abduction and adduction, we typically see the following:

• At the hip joint, the adductor muscles, including the adductor longus, adductor magnus, adductor brevis, pectineus, and gracilis, are lengthened, leaving them susceptible to injuries. The abductors of the hip, including the gluteus medius, gluteus minimus, and gluteus maximus, are normally in a shortened position.
• The knee joint actions do not include abduction or adduction (side-to-side bending) since it is primarily a hinge in the sagittal (front-to-back) plane. The two-joint adductors that lengthen at the hip may shorten at the knee, with the opposite holding true for the IT band on the lateral knee.
• The ankle joint is affected since the angle of the tibia coming down from the knee joint is angled in, causing ankle eversion. This postural positioning shortens the peroneal muscles (peroneus longus and brevis) and extensor digitorum longus, while lengthening the tibial muscles (tibialis anterior and posterior), flexor digitorum longus, flexor hallucis longus, and extensor hallucis longus.

Postural Deviations and Bow Legs:

Accompanying posture deviations often include the following:

• Anterior pelvic tilt
• External hip rotation or internal hip rotation
• Knee hyperextension
• Ankle pronation
• Duck feet (everted feet)
• Flat feet

What are the Symptoms of Bow Legs?

Common Pains and Limitations:

Due to the uneven stress distribution across these joints, the following symptoms are common.

• S-I joint pain
• Knee pain
• Hip pain
• Ankle pain
• Foot pain

Long-Term Risks and Issues:

Long-term untreated bow legs can lead to conditions due to abnormal load and wear on joints, muscles, bones, and various structures, such as:

• Premature arthritis in the knees
• Degenerative knees
• Hip arthritis
• Degenerative hips
• Low back pain
• Calf strain
• Plantar fasciitis
• Weak pelvic floor
• Osteoporosis
• Osteopenia

Physiological and Systemic Implications:

Due to the misaligned leg positioning, the pelvis and pelvic floor can be negatively affected. This can cause incontinence, urinary incontinence, constipation, pelvic organ prolapse, and reduced sensation in the genitals. The tightness across the lengthened adductors can cause limited mobility and reduced circulation at the hips, leading to decreased lymph flow, varicose veins, spider veins, and swelling in the legs and feet.

What Causes Bow Legs?

Bow legs in toddlers and young children are a normal physiological condition. Pediatric orthopedic surgeons often note that a child's legs appear curved due to their intrauterine positioning, which can persist during the first years of life. However, as the child starts walking, the legs typically start to straighten out and achieve a normal alignment. Proper motor learning and development, along with postural alignment, is highly dependent on adequate physical activity and variety of movements and demands.

In some cases, however, the bow legs persist even after age 3. This scenario requires a visit to an orthopedic surgeon or a pediatric specialist because it may indicate a more serious medical condition. Two conditions that can cause bow legs in older children include Blount's disease and rickets.

Blount's disease is a growth disorder that affects the growth plates at the knees, leading to a deformity of the tibia bone. This bone disease usually manifests itself in toddlers and young adolescents; an X-ray is often required to diagnose it.

On the other hand, rickets is a medical condition commonly caused by a deficiency in Vitamin D, calcium, or phosphorus. These nutrients are vital for healthy bone development, and their deficiency can lead to bone dysplasia, which can present as bow legs. This condition is often diagnosed through blood tests, physical examinations, and X-ray imaging.

One common symptom of these conditions is an abnormal walking pattern or intoeing. This is when the child walks with their feet turning inwards instead of pointing straight ahead. If you notice any of these signs in your child, it may be important to seek medical attention.

Treatment options vary depending on the underlying condition causing the bow legs. Physiologic bow legs in young children often resolve themselves and do not require specific treatment. However, if the condition is due to underlying bone disease, treatment can range from dietary supplements to correct nutritional deficiencies, physical therapy exercises to improve muscle strength and joint flexibility, or even surgery in severe cases.

So, while bow legs are common and usually harmless in young children, persistent bow legs in older children can be a sign of an underlying medical condition. Parents should monitor their child's development and seek medical advice if they notice any concerns. Remember, early detection and treatment can significantly improve the outcome for children with bow legs related to a medical condition.

Posture Terms Related to Bow Legs

• Knock Knees (Genu Valgum): This is the opposite of bow legs and refers to a condition where the knees angle in and touch each other when the legs are straightened. Also referred to as valgus knees or valgus stress.
• Hip External Rotation and Hip Internal Rotation: These often accompany bow legs, when the hip joint is rotated outwards away from the body's midline or inward toward the midline.
• Foot Pronation: This may also accompany bow legs and refers to the inward roll of the foot while walking or running.
• Anterior Pelvic Tilt: Due to the abnormal angles of the femurs coming into the hip sockets, the pelvis often tilts to find stability.