Why Does My Knee Give Out When I’m Walking?

Your knee may give out when you’re walking if the ligaments, cartilage, meniscus, or muscles that stabilize the knee are damaged or weakened. When these structures cannot properly support the joint, the knee may suddenly buckle or feel unstable during movement. In some cases, previous knee surgery or nerve-related conditions may also lead to knee instability.

If your knee frequently gives out, our fellowship-trained knee specialist, Dr. Charles Ruotolo, at Total Orthopedics & Sports Medicine, can perform a comprehensive evaluation to identify the exact cause of your knee instability. He carefully reviews your symptoms and may use advanced imaging tests to assess ligament injuries or other structural problems. Call 855-321-6784 to book your appointment with Dr. Charles Ruotolo in Commack.

What Are the Most Common Causes of Knee Instability?

The most common causes of knee instability include ligament injuries, cartilage damage, muscle weakness, and previous knee surgery. Patellar tracking issues, nerve-related conditions (such as peripheral neuropathy), or poor joint alignment can also cause persistent knee instability. Here’s how these conditions can make your knee unstable and contribute to joint pain:

Cartilage Damage

When your knee cartilage is damaged, the smooth cushioning between the bones starts to wear down. In these cases, the bones may no longer glide smoothly during walking and other activities. This uneven joint movement can lead to weakness or instability in the knee. At the same time, increased friction between the bones can irritate surrounding tissues and trigger inflammation. As the damage progresses, you may experience stiffness and pain during weight-bearing activities, such as:

• Walking for extended periods
• Climbing or descending stairs
• Squatting or kneeling
• Standing for long periods
• Getting up from a seated position
• Long-distance running
• Carrying heavy objects

Ligament Injuries

If the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), or lateral collateral ligament (LCL) is torn, your knee may feel unstable. You may also notice your knee shift, buckle, or give out while walking or changing direction. This abnormal movement can put extra stress on the cartilage, leading to permanent joint wear over time.

In fact, according to an NCBI study, clinically significant ligament injuries led to knee instability in 15.46% of patients. Among these cases, ACL, PCL, MCL, LCL, and multi-knee injuries were commonly associated with knee instability. Additionally, 16 patients developed delayed knee instability during fracture healing and later required ligament reconstruction.

Muscle Weakness

The muscles surrounding the knee play an important role in supporting and controlling joint movement. However, if your quadriceps, hamstrings, or hip muscles are weak, they cannot provide proper support during walking or exercising. This lack of muscular support can make your knee joint unstable or prone to frequent buckling. Moreover, abnormal movement patterns can put additional strain on ligaments and cartilage. Over time, this increased strain may lead to knee pain, inflammation, and reduced knee function.

Previous Knee Surgery

Prior knee surgery can sometimes contribute to instability if your joint did not fully recover after the procedure. In some cases, scar tissue formation may restrict normal knee movement and affect joint mechanics. Similarly, weakened muscles after surgery can reduce the structural support that stabilizes the knee.

For example, according to the NIH, muscle weakness after total knee arthroplasty (TKA) can temporarily affect knee stability. In this study of 20 patients, knee extensor strength decreased by 42% and knee flexor strength decreased by 34% one month after surgery. But muscle strength and functional mobility generally returned to preoperative levels within three to six months after surgery.

Patellar Tracking

Patellar tracking problems can cause knee instability if the kneecap moves out of its normal position during knee motion. Normally, the patella glides smoothly at the end of the femur as you bend and straighten your knee. However, if the kneecap shifts too far to one side, it can cause uneven pressure across the joint and affect normal knee mechanics. Patellar tracking can also increase friction between the kneecap and the surrounding cartilage, leading to pain.

Neurological Issues

If the femoral, sciatic, or peroneal nerves are damaged, they may not send proper signals to the muscles that stabilize the knee joint. This nerve damage can weaken muscle control and coordination, causing knee instability. For example, peripheral neuropathy can impair sensation, balance, and muscle function in the legs, making it more difficult to control knee movement during walking. As time passes, this instability may also increase the risk of falls, joint pain, and further knee injury.

Is a Knee Giving Out a Sign of Arthritis?

Yes, a knee giving out (buckling or feeling unstable) is a common symptom of knee arthritis. As arthritis progresses, the cartilage that cushions the knee bones gradually degenerates, reducing the knee’s ability to absorb shocks. This cartilage loss also increases friction within the joint, which can trigger pain, swelling, and inflammation during daily activities.

In addition, arthritis can lead to bone spurs. These bony growths can interfere with normal joint movement and place additional stress on the surrounding tendons, including:

• Quadriceps tendon (connects the quadriceps muscles to the kneecap)
• Popliteus tendon (helps control knee rotation and stability)
• Patellar tendon (connects the kneecap to the shin bone)
• Hamstring tendons (support the back of the knee and help with stability)
• Pes anserine tendons (assist with knee flexion and provide medial knee support)

When these tendons are under constant stress, they can get irritated, inflamed, or weakened over time. This reduced support can make your joint unstable and prone to sudden knee buckling. In such cases, our expert knee specialist, Dr. Charles Ruotolo, carefully examines the condition of your knee cartilage, bone spurs, and tendons using advanced imaging tools.

Based on the diagnosis, he creates a personalized treatment plan that may include non-surgical treatments such as RICE protocol, NSAIDs, and PRP to reduce pain and manage knee osteoarthritis. If the joint damage is severe, Dr. Charles Ruotolo may recommend advanced surgical treatments to remove bone spurs and repair damaged structures. Call 855-321-6784 to explore your treatment options.

Can a Meniscus Tear Make Your Knee Feel Unstable?

Yes, a meniscus tear can make your knee feel unstable. The meniscus acts as a shock absorber between your thigh bone and shin bone. It also helps stabilize your knee joint and surrounding muscles. However, when the meniscus is torn, it no longer distributes pressure evenly across the knee or supports normal joint movement. As a result, you may experience sensations of the knee giving out, frequent knee buckling, and locking during daily activities.

In some cases, a torn meniscus fragment may get stuck between the joint surfaces, disrupting normal knee motion. This mechanical interference can cause sudden knee instability. ACL or meniscus tears may also trigger pain, swelling, and muscle weakness, which can reduce knee joint function. In fact, according to a PubMed-indexed cohort study of 327 patients, lateral meniscus tears (LMTs) were associated with a higher risk of residual rotatory knee instability.

How Is Knee Buckling Different From Knee Weakness?

Knee buckling refers to a sudden loss of knee stability that causes joint collapse while standing or walking. In contrast, knee weakness occurs when the muscles around the knee, particularly the quadriceps and hamstrings, cannot properly support the joint. Besides that, knee buckling is often associated with ligament injuries, meniscus tears, or joint instability. On the other hand, knee weakness is more commonly linked to nerve-related conditions or prolonged inactivity.

While knee weakness can also contribute to knee buckling, buckling typically involves a sudden loss of joint stability rather than a gradual loss of strength. For example, a person with weak quadriceps muscles may struggle to support the knee during movement. However, a patient with an ACL tear may experience unexpected knee buckling during walking or pivoting. In some cases, both ACL symptoms and muscle weakness can co-occur, further reducing knee stability. Here are some additional differences between knee buckling and knee weakness:

Knee Buckling	Knee Weakness
Happens suddenly	Develops gradually
Often causes falls	Rarely causes falls
Triggered by movement	Triggered by fatigue
May include locking/catching	No locking sensation
Often one-sided	Can affect one or both knees
May need immediate treatment	Improves with rest

When Should You See a Doctor for Persistent Instability?

You should consult our knee specialist, Dr. Charles Ruotolo, if you experience repeated knee buckling, ongoing instability while walking, or difficulty supporting your body weight. You should also seek medical attention if the instability is accompanied by pain, swelling, stiffness, locking, or difficulty walking. Other than that, medical care is essential if you notice a reduced range of motion, difficulty climbing stairs, or weakness around the knee.

These symptoms may indicate an underlying knee condition that requires prompt evaluation and treatment. However, if you delay treatment in these cases, it may lead to permanent structural damage, such as:

• Cartilage breakdown: Progressive degeneration of the knee cartilage can lead to osteoarthritis and loss of smooth joint movement.
• Worsening meniscus tears: Minor tears can worsen over time, increasing pain and instability.
• Joint space narrowing: Loss of cushioning leads to bone-on-bone contact and increased pain.
• Bone spur formation: Extra bone growth can restrict movement and worsen stiffness.
• Reduced mobility: Progressive loss of normal knee movement and function.
• Muscle atrophy: Weakening and shrinking of thigh muscles due to reduced use and pain.
• Joint misalignment: Abnormal knee tracking that affects gait and balance.
• Persistent inflammation: Long-term swelling that increases pain and stiffness.

How Do Doctors Identify the Cause of Knee Buckling?

To identify the underlying cause of knee buckling, our orthopedic specialist, Dr. Charles Ruotolo, reviews your symptoms, medical history, and any prior knee surgeries. During the physical examination, he assesses your knee stability, muscle strength, range of motion, and walking patterns to identify signs of joint dysfunction. After that, he may order imaging tests such as X-rays, MRI scans, or an ultrasound.

X-rays can show bone alignment and signs of arthritis, while MRI scans provide detailed images of soft tissues, including ligaments, meniscus, and cartilage. Similarly, ultrasound can help evaluate soft tissue injuries and inflammation in real time. In addition to physical examination and imaging tools, Dr. Charles Ruotolo may ask the following questions to confirm the diagnosis:

• When did you first notice your knee giving out?
• Does the knee buckle during specific activities, such as walking, climbing stairs, or exercising?
• Do you feel a popping sound, catching, or locking sensation before the knee gives out?
• Have you experienced a recent knee injury or fall?
• Do you have a history of ACL tears, meniscus injuries, or previous knee surgery?
• Is the instability accompanied by pain, swelling, or stiffness?
• Do you feel the knee shifting or moving out of place during activity?
• Have you noticed weakness, numbness, or tingling in your leg?

What Is the Best Treatment for Chronic Knee Instability?

For mild to moderate knee instability, our surgeon may recommend knee bracing, targeted injections, PRP, and ice therapy. These treatments can help improve joint stability, reduce inflammation, and restore function. However, if you have persistent knee instability, our knee specialist, Dr. Charles Ruotolo, may recommend the following surgical treatments to improve joint function:

• ACL Reconstruction: Replaces a torn ACL to restore knee stability during movements.
• PCL Reconstruction: Rebuilds the posterior cruciate ligament to improve knee support and control.
• Meniscus Repair: Preserves damaged meniscal tissue to improve stability and shock absorption.
• Meniscus Transplantation: Replaces a missing meniscus to restore cushioning and joint function.
• Patellar Stabilization Surgery: Fixes kneecap instability and prevents recurrent dislocations during activity.
• Cartilage Restoration Procedures: Repairs damaged cartilage surfaces to improve joint movement and reduce pain.
• Osteotomy: Realigns knee bones to reduce pressure on damaged joint compartments.
• Arthroscopic Debridement: Removes damaged tissue and loose fragments interfering with knee mechanics.
• Partial Knee Replacement: Replaces the damaged part of the knee while preserving healthy cartilage and bone.
• Total Knee Replacement: Restores stability and mobility by replacing severely damaged knee joint surfaces.

How Long Does Knee Instability Recovery Take?

It typically takes a few weeks to more than a year to recover from knee instability, depending on the underlying cause and the treatment required. For instance, mild instability caused by muscle weakness or minor soft tissue injuries may improve within 4 to 8 weeks with non-surgical treatment. However, recovery can take 3 to 6 months if you have cartilage damage, meniscus injuries, or patellar instability. Similarly, if surgery is necessary, recovery is often longer and may range from 6 to 12 months or more.

How Can You Prevent Knee Instability While Walking?

To reduce the risk of knee instability while walking, avoid sudden twisting movements and use assistive devices or a knee brace if recommended by your doctor. You should also walk on even surfaces to reduce unnecessary stress on the knee and lower the risk of sudden buckling. Similarly, maintaining good posture and taking shorter, controlled steps may improve balance and joint stability during movement.

Here are some additional strategies that can help lower the risk of knee instability while walking:

• Use handrails on stairs: Provides extra support and reduces the risk of sudden knee buckling.
• Wear properly fitted footwear: Improves balance and helps maintain proper lower-limb alignment.
• Replace worn-out shoes regularly: Avoids uneven weight distribution that can affect knee stability.
• Avoid carrying heavy loads: Excess weight can increase pressure on an affected unstable knee.
• Take breaks during prolonged walking: Prevents fatigue that may reduce knee control and stability.
• Follow your prescribed knee treatment plan: Helps manage underlying conditions contributing to instability.
• Proprioception training: Improves your body’s ability to sense knee position and movement, helping reduce unexpected buckling.

What Exercises Can Help Improve Knee Joint Stability?

Straight leg raises, mini squats, wall sits, and single-leg balance exercises can improve knee stability. Other than that, hamstring curls, side leg raises, calf raises, resistance band walks, and terminal knee extensions can also improve joint control and balance. Here’s how you can perform these strengthening exercises effectively to improve overall knee joint function:

• Straight Leg Raises: Lie on your back with one leg bent and the other straight. Tighten your thigh muscle and lift the straight leg to the height of the bent knee.
• Mini Squats: Stand with feet shoulder-width apart. Slowly bend your knees slightly (about 30–45 degrees), keeping your back straight.
• Wall Sits: Stand straight with your back against a wall and slide down until your knees are slightly bent. Hold this position while keeping pressure evenly through both feet.
• Single-Leg Balance: Stand on one leg while keeping your body upright. Hold your balance for a few seconds, then switch legs.
• Hamstring Curls: Stand holding support, bend one knee to bring your foot toward your buttocks, then slowly lower it back down.
• Side Leg Raises: Lie on your side and slowly lift the top leg straight up, then lower it.
• Calf Raises: Stand upright and slowly rise onto your toes, hold briefly, then lower your heels back down.
• Resistance Band Walks: Put a resistance band around your legs and take slow side steps while keeping tension in the band.
• Terminal Knee Extensions: Attach a resistance band behind the knee, slightly bend the knee, then fully straighten it while tightening the thigh muscles.

We Can Help You Identify the Root Cause of Knee Buckling — Visit Us Now in Commack!

If you have persistent knee buckling, even simple activities such as walking or climbing stairs may become difficult. You may experience recurring pain, swelling, stiffness, and an increased risk of permanent joint degeneration. Without treatment, these symptoms can worsen, leading to progressive cartilage damage.

As a Castle Connolly Top Doctor, our knee specialist, Dr. Charles Ruotolo, at Total Orthopedics & Sports Medicine, has extensive experience diagnosing the underlying causes of knee buckling. After identifying the source of your symptoms, he designs a personalized treatment plan that may include non-surgical treatments or surgical procedures to restore joint function. Call us today at 855-321-6784 or visit 500 Commack Road, Building E, Suite 150B, Commack, NY 11725 to book your appointment.

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