Genu varum, commonly known as bow legs, describes an outward bowing of the legs at the knees, leaving a noticeable gap when the feet are together. While this alignment is a common and often self-correcting developmental stage in infancy, its persistence or acquisition in adulthood can become a significant medical issue. For skeletally mature individuals, this mechanical misalignment places undue stress on the knee joint, frequently leading to chronic pain and functional decline. The primary purpose of medical intervention in adults is to restore proper mechanical alignment to the lower limb, reducing joint stress and preventing long-term damage.
Understanding Genu Varum in Skeletally Mature Individuals
The medical concern surrounding persistent bow legs in adults arises from weight distribution across the knee joint. In a leg with varus alignment, the mechanical axis—the line of force from the hip center to the ankle center—shifts inward, passing through the inner, or medial, compartment of the knee. This malalignment results in a disproportionate loading of the medial compartment, which can bear up to 70 to 80% of the joint load during walking.
This uneven pressure accelerates the wear and tear of the articular cartilage on the medial side, a process known as medial compartment overload. This structural stress leads to the accelerated development of unicompartmental osteoarthritis, causing pain, stiffness, and joint deterioration. Since the adult bone structure is fixed, the underlying anatomical issue cannot resolve spontaneously. The goal of addressing adult genu varum is to preserve the joint by correcting this mechanical flaw before the arthritis becomes severe.
Non-Surgical Approaches for Symptom Management
For adults with mild genu varum or those who are not candidates for surgery, non-surgical methods focus primarily on managing symptoms and slowing the progression of joint degeneration. These conservative strategies do not physically straighten the fixed bone structure but instead work to alleviate the pain and mechanical stress caused by the malalignment.
Physical therapy is a common treatment, with exercises aimed at strengthening the muscles surrounding the knee and hip to improve gait stability and overall posture. Weight management is also a highly effective non-surgical approach, as a lower body weight directly reduces the total load transmitted across the stressed knee joint.
Custom-made orthotic insoles, specifically lateral wedge insoles, are sometimes used to mechanically shift the weight-bearing axis slightly away from the damaged medial compartment. While they provide symptom relief by redistributing pressure, their effect is limited to biomechanical support and they do not create a permanent correction of the bony alignment. Pain relief medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs), may also be prescribed to control inflammation and discomfort associated with early arthritis.
Surgical Realignment Procedures
Surgery is the definitive method for correcting the underlying bony alignment in adults with genu varum. The primary goal of these procedures is to shift the mechanical weight-bearing axis of the leg back toward the center or slightly to the outer (lateral) side of the knee. This realignment offloads the damaged medial compartment, which alleviates pain and potentially halts the progression of osteoarthritis.
The most common procedure for correcting genu varum is the High Tibial Osteotomy (HTO), which involves surgically cutting and reshaping the upper part of the shin bone (tibia). In an open wedge HTO, a wedge-shaped gap is created and held open with a bone graft or a metal plate to physically straighten the leg and redirect the weight line. HTO is typically recommended for younger, active patients who have localized arthritis in the medial compartment, as it allows them to retain their natural knee joint.
If the angular deformity originates higher up in the thigh bone, a Distal Femoral Osteotomy may be performed to correct the alignment from the femur. For patients with severe varus deformity, surgeons may perform a double-level osteotomy involving both the tibia and the femur to achieve the necessary correction. These realignment surgeries aim to preserve the natural knee joint, often delaying the need for a total joint replacement.
When genu varum has progressed to severe, widespread arthritis that is no longer localized to one compartment, or for older adults, a Total Knee Arthroplasty (TKA), or knee replacement, becomes the appropriate treatment. During TKA, the damaged joint surfaces are removed and replaced with artificial components, and the surgeon simultaneously corrects the bow leg alignment to restore a neutral mechanical axis. In cases of extreme deformity, specialized constrained implants may be necessary to ensure the new joint is stable after correction.
Post-Intervention Recovery and Expectations
Recovery following surgical correction, particularly High Tibial Osteotomy, involves a structured rehabilitation process. Patients typically require restricted weight-bearing, often using crutches, for the first six weeks or more to allow the altered bone to heal. Progression to full weight-bearing is gradual and determined by X-ray evidence of bone union and the surgeon’s protocol.
Post-operative physical rehabilitation is a necessary component of recovery, beginning soon after surgery to manage swelling and restore joint range of motion. Dedicated physiotherapy sessions focus on strengthening the quadriceps and other surrounding muscles to improve stability and gait mechanics as the patient begins to bear weight. A complete recovery, allowing a return to most normal activities, can take approximately three to six months, with a full return to high-impact sports sometimes taking up to nine to twelve months.
Following a successful osteotomy, the long-term expectation is reduced pain, improved knee function, and a significant delay in the progression of severe osteoarthritis. The mechanical correction provided by the surgery is an enduring alteration that improves the distribution of forces across the knee, offering a long-term strategy for joint preservation. Patients who undergo a Total Knee Arthroplasty can expect a quicker return to walking, typically within weeks, with the long-term prognosis being a substantial reduction in pain and restored mobility.