Genu valgum, commonly known as knock-knees, describes an angular deformity where the knees angle inward and touch or nearly touch when a person stands with their feet apart. This alignment issue creates a noticeable gap between the ankles, altering the mechanical axis of the leg. It is a common condition, especially observed during certain phases of childhood development, but it can persist or develop later in life due to various factors. Treatment approaches for genu valgum are highly individualized, depending on the patient’s age, the underlying cause of the deformity, and the overall severity of the misalignment.
Understanding the Underlying Causes
The reasons for a valgus knee can be broadly categorized into physiological and pathological causes. Physiological genu valgum is a normal developmental phase, most prominent in children between the ages of three and five, and it typically self-corrects by age seven or eight as the child grows. This developmental pattern is a benign process and rarely requires active intervention beyond observation.
Pathological genu valgum occurs when the condition is severe, affects only one leg, or persists beyond the typical self-correction age. Underlying conditions include metabolic bone diseases, such as rickets (caused by Vitamin D deficiency), which weakens the bones. Trauma to the growth plates from an injury or infection, certain skeletal dysplasias, and arthritis in the knee joint can also lead to acquired valgus deformity. Mechanical imbalances, often linked to obesity, place excessive stress on the knees, potentially worsening the alignment over time.
Non-Surgical Management Strategies
For cases that are not severe or are associated with muscular imbalance, management involves targeted physical therapy and lifestyle modifications. The goal of these non-surgical strategies is to improve the biomechanics of the lower extremity by strengthening specific muscle groups. Strengthening the muscles surrounding the hip is often prioritized, as weakness in these areas can allow the femur to rotate inward, contributing to the knee valgus.
Exercises focus heavily on the hip abductors, particularly the gluteus medius, which stabilizes the pelvis and controls the inward rotation of the thigh bone. Clamshell exercises and side-lying leg raises are effective for isolating and strengthening this muscle group. Exercises targeting the vastus medialis oblique (VMO), the inner portion of the quadriceps, improve kneecap tracking and overall knee joint stability. Squats or step-ups performed with a focus on maintaining proper knee alignment are often incorporated into a rehabilitation program.
Stretching tight structures is important for restoring optimal alignment. The iliotibial (IT) band and the hip adductor muscles can become tight, pulling the leg into a position that exacerbates the valgus angle. Consistent stretching helps release this tension and allows the leg to move closer to a neutral position. Managing body weight also reduces compressive forces and abnormal loading on the misaligned knee joint, preventing the condition from worsening.
Supportive Devices and Orthotics
Supportive devices are frequently used in conjunction with physical therapy to manage alignment and reduce symptoms. Custom-designed foot orthotics (specialized shoe inserts) adjust the foot and ankle alignment. By correcting excessive pronation or flat feet, orthotics improve the overall lower limb axis.
These devices provide cushioning and support, distributing weight more evenly across the foot. Orthotics may feature a medial post (a thicker portion on the inner edge) to counteract the inward collapse. In pediatric cases, specific braces or splints, sometimes worn nocturnally, may be prescribed to guide the growth of the long bones into a straighter alignment.
Criteria and Types of Surgical Correction
Surgical intervention is reserved for severe cases of genu valgum that cause significant pain, functional limitations, or have failed to respond to conservative treatments. Criteria for surgery include progression of the deformity in adolescents or a mechanical axis deviation significant enough to predict future joint damage, such as early-onset osteoarthritis. The type of surgical procedure chosen depends primarily on the patient’s skeletal maturity.
For children and adolescents with open growth plates, guided growth surgery (hemiepiphysiodesis) is the preferred technique. This minimally invasive procedure involves temporarily placing a small plate or screws on the inner side of the growth plate. By slowing growth on the inner (medial) side of the bone, the outer (lateral) side continues growing, which gradually straightens the limb. The hardware is removed once the desired correction is achieved.
For skeletally mature adolescents and adults whose growth plates have closed, an osteotomy is the definitive procedure for correcting the alignment. This surgery involves cutting the bone (typically the distal femur or proximal tibia) and realigning the segments to restore the mechanical axis. The corrected bone is then stabilized with internal fixation (such as plates and screws) to allow for healing in the new position. This approach achieves immediate correction and relieves excessive pressure on the knee joint.