Valgus is an orthopedic term describing an angular deviation in a limb where the segment of the bone furthest from the body’s center is angled away from the body’s midline. This structural misalignment occurs in the coronal plane, the vertical plane dividing the body into front and back sections. Valgus specifically denotes an outward angulation, contrasting with varus, which signifies an inward angulation toward the midline. This deviation affects joints by creating an altered mechanical axis that changes how weight is distributed.
Understanding the Valgus Alignment
Valgus alignment describes a change where the distal part of a limb moves laterally relative to the proximal part. In a properly aligned limb, the mechanical axis—the line of force transmission—runs straight through the center of the joint. When valgus is present, this axis shifts laterally, often resulting in a “knock-kneed” appearance.
This lateral shift places a greater proportion of compressive forces onto the lateral compartment of the affected joint. In the knee, valgus alignment results in increased pressure on the outer side of the joint, which can lead to premature cartilage wear. The change in alignment also affects the entire kinetic chain, potentially causing compensating internal rotation at the hip and excessive pronation in the foot during walking. This altered loading pattern impacts surrounding ligaments and tendons, which struggle to stabilize the misaligned joint.
Common Forms of Valgus Deformity
The manifestation of valgus can occur in several common areas of the body, each with a distinct name and set of consequences.
Genu Valgum (Knock-Knees)
One of the most recognized forms is Genu Valgum, commonly known as knock-knees, where the knees touch or nearly touch when a person stands with their ankles apart. This presentation is considered a normal, temporary stage of development in up to 75% of children between the ages of three and five, typically self-correcting by age seven or eight. When Genu Valgum persists into adolescence or adulthood, it becomes a pathological condition that alters gait mechanics. This persistent misalignment causes chronic stress on the lateral side of the knee joint and increases the long-term risk of developing lateral compartment osteoarthritis. For adults, a tibiofemoral angle exceeding 10 degrees of valgus is often considered outside the normal range.
Hallux Valgus (Bunion)
Another frequent valgus condition is Hallux Valgus, commonly called a bunion, which affects the big toe joint. This deformity is characterized by the big toe deviating laterally toward the second toe. This lateral angulation is accompanied by the metatarsal bone shifting medially, creating a bony prominence (the characteristic visible bump) on the medial side of the foot at the base of the toe.
Ankle Valgus (Pes Valgus)
Ankle Valgus, also known as Pes Valgus or hindfoot valgus, is a condition where the heel bone angles outward, often causing the foot to flatten and the arch to collapse. This outward turning of the heel results in a flat-foot presentation and excessive eversion at the subtalar joint. This foot alignment can initiate a chain reaction of misalignment up the leg, contributing to a dynamic valgus force at the knee during movement.
What Leads to Valgus Development
The development of a valgus alignment can be traced to a combination of factors, ranging from normal growth patterns to acquired disease processes. The physiological valgus that occurs in early childhood is a developmental stage that resolves naturally as the child’s bones mature.
Valgus can also be a sign of underlying systemic conditions, particularly those involving bone health. Nutritional deficiencies, such as a lack of Vitamin D and calcium, can lead to rickets, a disease that weakens the bones and causes improper growth and alignment. This type of valgus is often bilateral, affecting both limbs symmetrically.
Acquired valgus can result from local factors like trauma, where a fracture near a growth plate in a child can cause premature closing or damage, leading to progressive angular deformity. In adults, the condition may develop secondary to degenerative joint diseases like rheumatoid arthritis or severe osteoarthritis, which can erode joint surfaces and compromise ligament stability. Genetic disorders, bone dysplasias, or syndromes, such as hereditary multiple exostoses, can also predispose an individual to developing a persistent valgus alignment.
Signs That Require Seeing a Doctor
While some mild valgus alignments are asymptomatic, certain signs indicate the need for a professional medical evaluation by an orthopedic specialist. Persistent pain in the knee, hip, ankle, or foot suggests the misalignment is causing pathological stress on the joints and surrounding soft tissues. This discomfort results from uneven load distribution and subsequent joint wear.
A rapid or noticeable progression of the deformity, or the development of valgus in an older child (over age seven) or an adult, should prompt a doctor’s visit. Asymmetry, where only one limb is affected or one side is significantly worse, often suggests a pathological cause like a prior injury, infection, or tumor. Functional limitations, such as a noticeable limp, difficulty running, or instability when walking, also require professional assessment. For Genu Valgum, an intermalleolar distance—the gap between the ankles when the knees are touching—that exceeds 8 centimeters warrants investigation.