In general, a varus or bowlegged deformity refers to an outward bending of a specified deformed body part away from the midline of the body. In a varus deformity of the knee, the angulation of the knees is bent outward, away from the midline of the body. The opposite of genu varus or genu valgus (knock kneed) refers to a deformity toward the midline of the body.

This deformity may be present as a normal stage that most children pass through, and grow out of by age 9. However it may persist later in life if the legs do not straighten or are not treated. It may be also be caused by trauma; injury to the cruciate ligaments; joint disease; muscle weakness; or fracture. It is often times associated with obese children and early walkers.

Manifestations may be related to the underlying cause of the condition and may include: pain; swelling; weakness; deformity; alteration in gait; abnormal erosion of articular cartilage with loss of flexibility of the joint; or instability of the knee.

Diagnostic measures may involve a physical examination which includes: stability testing (Lachman's test varus/valgus stress testing); x-ray; magnetic resonance imaging (MRI); and range-of-motion (ROM) testing (normal ROM for the knee is from 0 to 130°-140°). In addition, laboratory tests may be done to rule out non-mechanical disorders.

Varus deformities often times correct spontaneously at a young age. Normal genu varum evolves to a physiologic genu valgum by three years of age in normal growth and development. Conservative treatment may involve immobilization with orthotics followed by mobilization and rehabilitation. Anti-inflammatory medications may be implemented. Surgery may be indicated which includes stapling of the epiphysis or some sort of osteotomy procedure if marked deformity persists.

Following injury, if the knee is stabilized, a return to pre-injury activity level may be possible. A long-term, secondary or chronic instability of the knee may result if serious injury is untreated. Degenerative osteoarthritis of the knee may occur if the deformity is not corrected or treated.

• Congenital or developmental defects refer to normally static, structural or inherent body abnormalities which are typically present at birth and are generally incapable of improvement or deterioration.  These include but are not limited to vertebral anomalies. Congenital or developmental defects are not diseases or injuries within the meaning of applicable legislation as outlined in 38 CFR 3.303(c) and 38 CFR 4.9. The M21-1 includes a section devoted entirely to this subject (Service Connection (SC) for Congenital, Developmental, or Hereditary Disorders). Diseases of congenital, developmental, or familial, hereditary origin may be subject to SC if they first manifest in service, pre-exist service but progress at a high rate during service, are presumptively related to service, or for disabilities resulting from an overlying injury or disease of a congenital defect.

• When there is evidence showing a history of in-service trauma to a joint, utilize 38 CFR 4.71a, DC 5010 for rating purposes, which indicates the etiology of the condition is trauma-based. Post-traumatic arthritis is evaluated based on limitation of motion (LOM), dislocation, or other specified instability of the affected joint under the corresponding DC for the joint, and not evaluated utilizing arthritis criteria, such as 38 CFR 4.71a, DC 5003.

• The rating schedule for musculoskeletal was updated on February 7, 2021. Protection still does apply and should be considered with existing evaluations (38 CFR 3.951(a)).

• When evaluating genu recurvatum, which involves hyperextension of the knee beyond 0 degrees of extension, under 38 CFR 4.71a, DC 5263

  • do not also evaluate separately under 38 CFR 4.71a, DC 5261, but

  • DO evaluate separately under other evaluations if manifestations that are not overlapping, such as limitation of flexion under 38 CFR 4.71a, DC 5260, are attributed to genu recurvatum, and

  • do not evaluate separately under 38 CFR 4.71a, DC 5257; however, if instability is manifested from genu recurvatum evaluate based on the criteria that will provide the highest evaluation.

• None.