Knock Knee Deformity

Knee discomfort can significantly affect daily life, and when accompanied by swelling, tenderness, or redness, it is important to seek medical attention. One possible cause of knee pain is knock knee deformity, where the knees angle inward, often leading to symptoms such as pain, instability, and difficulty walking. At Complete Orthopedics, our specialists are committed to providing the best care for knee pain, offering both non-surgical and surgical treatment options.

How Common It Is and Who Gets It? (Epidemiology)

Knock knee deformity, also known as genu valgum, is common in children and typically resolves as they grow older. However, it can persist into adulthood, especially if it is caused by underlying conditions such as arthritis. The condition is often seen in young children as part of normal growth, but in adults, it is more commonly linked to degenerative joint diseases, such as osteoarthritis or rheumatoid arthritis.

Why It Happens – Causes (Etiology and Pathophysiology)

Knock knee deformity often develops during childhood as part of normal skeletal growth. However, it can persist or develop later in life due to various factors, including rickets (a vitamin D deficiency), genetic disorders like Morquio syndrome, and injuries to the knee joint. In adults, knock knees are frequently caused by osteoarthritis or rheumatoid arthritis, which lead to cartilage damage and joint misalignment.

How the Body Part Normally Works? (Relevant Anatomy)

The knee joint consists of the femur (thigh bone) and tibia (shinbone), with the patella (kneecap) sitting on the front of the femur. The knee is designed to allow smooth flexion and extension. When a person has knock knees, the alignment of the femur and tibia is altered, causing the knees to angle inward. This misalignment can affect the patella’s position and may lead to additional strain on the knee joint.

What You Might Feel – Symptoms (Clinical Presentation)

Common symptoms of knock knee deformity include knee pain, especially on the outer side of the knee, and difficulty walking or standing. The pain may be aggravated by activity, and the individual may develop a noticeable limp. In more severe cases, the knees may rub together, and there may be a visible gap between the ankles when standing. The misalignment can also increase the risk of patellar dislocation and lead to chronic knee pain.

How Doctors Find the Problem? (Diagnosis and Imaging)

Diagnosing knock knee deformity involves a thorough physical examination, including an assessment of gait and leg alignment. The doctor may take measurements of the legs to check for discrepancies and evaluate joint movement. Imaging studies such as X-rays may be used to assess the severity of the deformity and any underlying joint damage. Blood tests may also be conducted to rule out deficiencies in vitamin D, calcium, or phosphate.

Classification

Knock knee deformity is classified by severity, from mild cases where the misalignment is minimal to more severe cases with significant angular deformity. In children, the deformity is often physiological and resolves on its own, while in adults, the condition is usually associated with degenerative joint diseases.

Other Problems That Can Feel Similar (Differential Diagnosis)

Other conditions that may present with symptoms similar to knock knees include flat feet, osteoarthritis, and patellofemoral pain syndrome. These conditions can also cause knee pain, gait abnormalities, and misalignment, so a proper diagnosis is necessary to differentiate between them.

Treatment Options

Non-Surgical Care

For children with physiological knock knees, no treatment is usually required, but regular monitoring is necessary to ensure that the condition resolves as they grow. In adults, non-surgical management may include physical therapy to strengthen the muscles around the knee and improve alignment. Orthotic devices such as braces, arch pads, and specially designed shoes may also help. For individuals with obesity, weight loss may reduce the severity of the deformity.

Surgical Care

Surgery is required in more severe cases, especially when the deformity is caused by underlying bone diseases or arthritis. In children, guided growth procedures may be used to correct the alignment. In adults, total knee replacement is often recommended, especially in cases of osteoarthritis or rheumatoid arthritis. High tibial osteotomy may be performed for milder cases to realign the knee.

Recovery and What to Expect After Treatment

Recovery from knock knee deformity treatment depends on the type of intervention. After surgery, patients typically require postoperative care, including pain management, icing, and rest. Physical therapy is crucial for rehabilitation and includes exercises to restore knee function and strength. Gradual return to activity is encouraged, with an emphasis on low-impact exercises initially. Follow-up appointments will monitor progress and ensure proper healing.

Possible Risks or Side Effects (Complications)

Possible complications from knock knee treatment include infection, blood clots, or nerve damage, particularly if surgery is required. In total knee replacement surgeries, excessive stretching of the knee joint structures could lead to damage to the common peroneal nerve, which controls foot movement.

Long-Term Outlook (Prognosis)

The long-term prognosis for individuals with knock knee deformity varies depending on the severity and underlying cause. In children, the condition often improves with age. For adults, early intervention and appropriate treatment can prevent further joint damage and improve mobility. Surgical options like total knee replacement offer long-term relief from pain and deformity, providing patients with improved function and quality of life.

Out-of-Pocket Costs

Medicare

CPT Code 27475 – Guided Growth (Hemiepiphysiodesis): $158.81
CPT Code 27447 – High Tibial Osteotomy (HTO) / Total Knee Replacement (TKR) (Medial Opening Wedge): $303.02
CPT Code 27418 – Tibial Tubercle Osteotomy: $193.59

Under Medicare, 80% of the approved amount for these procedures is covered once the annual deductible has been met. The remaining 20% is typically the patient’s responsibility. Supplemental insurance plans—such as Medigap, AARP, or Blue Cross Blue Shield—usually cover this 20%, meaning most patients will have little to no out-of-pocket expenses for Medicare-approved surgeries. These supplemental plans work directly with Medicare to ensure full coverage for the procedure.

If you have secondary insurance—such as Employer-Based coverage, TRICARE, or Veterans Health Administration (VHA)—it serves as a secondary payer once Medicare processes the claim. After your deductible is satisfied, these secondary plans may cover any remaining balance, including coinsurance or small residual charges. Secondary plans typically have a modest deductible, ranging from $100 to $300, depending on the specific policy and network status.

Workers’ Compensation
If your knee surgery is work-related, Workers’ Compensation will fully cover all treatment-related costs, including surgery, hospitalization, and rehabilitation. You will have no out-of-pocket expenses under an accepted Workers’ Compensation claim.

No-Fault Insurance
If your knee injury resulting in surgery is caused by a motor vehicle accident, No-Fault Insurance will cover all medical and surgical expenses, including guided growth, high tibial osteotomy, and total knee replacement. The only possible out-of-pocket cost may be a small deductible depending on your individual policy terms.

Example
James, a 61-year-old patient with knee osteoarthritis, required high tibial osteotomy (CPT 27447) and tibial tubercle osteotomy (CPT 27418). His estimated Medicare out-of-pocket costs were $303.02 for the HTO and $193.59 for the tibial tubercle osteotomy. Since James had supplemental insurance through Blue Cross Blue Shield, the 20% that Medicare did not cover was fully paid, leaving him with no out-of-pocket expenses for the procedures.

Frequently Asked Questions (FAQ)

Q. What causes knock knee deformity?
A. Knock knee deformity can be caused by a variety of factors, including normal growth in children, rickets, genetic disorders, trauma, and arthritis in adults.

Q. Can knock knee deformity be treated without surgery?
A. Yes, in many cases, non-surgical treatments like physical therapy, weight loss, and orthotic devices can help manage knock knee deformity.

Q. How long does recovery take after surgery?
A. Recovery time depends on the surgery performed, but generally, it takes several weeks to months, with a focus on physical therapy to regain strength and mobility.

Q. Is surgery always necessary for knock knee deformity?
A. No, surgery is not always necessary. In many children, the condition resolves naturally as they grow. In adults, surgery is usually considered when the deformity causes significant pain or functional limitations.

Q. Can knock knee deformity lead to other problems?
A. Yes, if left untreated, knock knee deformity can lead to osteoarthritis, meniscal tears, and other knee joint issues due to increased stress on the affected areas.

Summary and Takeaway

Knock knee deformity is a condition that causes the knees to angle inward, which can lead to pain, gait abnormalities, and other joint problems. While it is often a normal part of childhood development, it may persist or develop later in life due to various causes such as arthritis or trauma. Early diagnosis and appropriate treatment, whether non-surgical or surgical, are key to managing the condition and improving quality of life.

Who Performs This Treatment? (Specialists and Team Involved)

Orthopedic surgeons specializing in pediatric and adult knee surgery typically perform treatment for knock knee deformity. A team of physical therapists, radiologists, and other specialists may also be involved in the diagnosis and rehabilitation process.

When to See a Specialist?

If you or your child has knock knee deformity that persists beyond the typical age of correction, or if the condition causes pain or difficulty walking, it’s important to seek evaluation by a specialist.

When to Go to the Emergency Room?

Seek emergency care if you experience severe knee pain, swelling, or instability, especially if the knee appears to be dislocated or if there is significant trauma to the joint.

What Recovery Really Looks Like?

Recovery from knock knee deformity treatment typically involves a structured plan of physical therapy, gradual return to activity, and regular follow-up appointments to monitor progress. Most patients can expect to resume normal activities after a period of rehabilitation.

What Happens If You Ignore It?

Ignoring knock knee deformity can lead to worsening pain, gait abnormalities, and the development of osteoarthritis. It may also increase the risk of further joint damage and functional limitations.

How to Prevent It?

While some causes of knock knee deformity are genetic or related to growth, maintaining a healthy weight, engaging in regular physical activity, and addressing any joint issues early can help prevent or reduce the severity of the condition.

Nutrition and Bone or Joint Health

A balanced diet rich in calcium and vitamin D is essential for maintaining bone health and preventing conditions like rickets, which can lead to knock knee deformity. Proper nutrition supports bone strength and joint function.

Activity and Lifestyle Modifications

To prevent or manage knock knee deformity, it’s important to engage in regular low-impact exercises such as swimming or cycling. Avoiding activities that put excessive strain on the knee joint can also help reduce symptoms and prevent further damage.