Table of ContentsView AllTable of ContentsSymptomsCausesRisk FactorsDiagnosisTreatmentPrevention
Table of ContentsView All
View All
Table of Contents
Symptoms
Causes
Risk Factors
Diagnosis
Treatment
Prevention
Several issues can cause your knees to give out. A ligament or meniscus tear are obvious ones, but knee instability can also be due to arthritis and other inflammatory conditions, nerve damage, injuries such as dislocation, or a few other causes.
Knee weakness and instability may begin suddenly or develop slowly over time. It may be the only symptom you have, or your knee may also hurt, pop, bruise, or swell.
This article explores seven possible reasons why your knees are giving out, symptoms of knee weakness, how these problems are diagnosed, and the treatment options that are available to you.
Martin-dm / Getty Images
What Are the Signs and Symptoms of Knee Weakness?
With some conditions, you may only experience the symptom of having unstable knees.
However, with others, you may also have:
Complications of Knee Buckling
Complications of weak knees may include:
You should see your healthcare provider if you are experiencing the sensation of your knee giving out.
Seek immediate medical care if your knee gives out and you experience severe pain, significant swelling, or a fever.
What Causes My Knee to Suddenly Give Out?
Injuries or medical conditions that can cause your knee to feel weak or give out include:
Ligament Tears
The knee is a hinge joint that connects the large thigh bone to the lower leg bones. Connective tissues called ligaments connect bones to bones and help stabilize the joint.
There are severalligaments in the knee, but the four major ones are:
Partial or complete tears to one or more of the ligaments in the knee can cause knee instability. Types of ligament tears include:
Anatomy of the Knee
Meniscal Tear
The cartilage pads, known asmenisci, are the shock absorbers of the knee and help stabilize it. There are two per knee—one on the inside and one on the outside.
A meniscus tear may occur with activities such as twisting, turning, and pivoting. A meniscal tear is more common in people ages 30 and older, as the menisci start to weaken around this time.
Symptoms may include:
Patellar Dislocation or Subluxation
The kneecap, or patella, normally glides through a groove. A direct blow to the kneecap, usually from an accident or sports injury, can dislocate it from this groove. This is called patellar instability.
Two types of patellar instability include:
Plica Syndrome
Symptoms include:
Natural Ways to Fight Inflammation
Arthritis
Arthritis, an inflammatory condition, can lead to the knee giving out. There are many types of arthritis that can impact the knee. These includeosteoarthritis,rheumatoid arthritis, andinflammatory arthritis.
In general, symptoms of knee arthritis may include:
Nerve Damage
Thefemoral nerveis located in the pelvis and goes down the thigh and the shinbone. Femoral nerve damage can make it feel like your knee could give out or is giving out. It can also cause a tingling or burning pain around the knee.
Femoral nerve damage can happen if:
Multiple Sclerosis
Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system and damages the protective covering of nerve cells.
MS can cause muscle weakness in the hamstring and quadriceps muscles that support the knee. It can also lead to muscle spasms as well as balance and gait problems.Each of these issues may contribute to a feeling that the knee is giving out.
Who Is at Risk for Injuries Related to Knee Instability?
Risk factors for injuries related to knee weakness include:
How Is Knee Instability Diagnosed?
To diagnose knee instability your doctor will first take a detailed medical history. You may also get a physical exam, as well as imaging tests done.
Physical Exam
An examination of the knee first looks for general findings, such as:
Special tests may also be done during this example. For example, to examine for meniscal tears and to evaluate the ligaments, a healthcare provider may perform the:
Imaging Studies
The type of imaging test done depends on the suspected problem.
For example, X-rays may be helpful for evaluating a dislocation, but magnetic resonance imaging (MRI) may be used to identify ligament and cartilage injuries.
How Do You Treat Weak Knees?
Treatment for knee instability will vary depending on the specific cause. Treatments may include rest, ice, compression, and elevation, better known as theRICEmethod, as well as nonsteroidal anti-inflammatory medications for pain.
Conditions such as a torn ACL or arthritis may require knee surgery, but other conditions may benefit more from physical therapy andknee rehab exercises.
A knee brace may also be used in some cases.
How Do You Prevent Knee Instability?
See your healthcare provider if you are experiencing any knee-related symptoms so a knee condition, if present, can be treated as early as possible. In some cases, this may help you avoid knee instability.
Other preventative measures include:
Unloader Knee Brace for Osteoarthritis
Summary
Knees may buckle due to tears, dislocation, certain conditions, as well as nerve damage. Your knees giving out may be the only symptom, or you may also experience symptoms such as popping, pain, stiffness, and reduced movement.
To diagnose knee instability your doctor will take a detailed medical history, give you a physical exam, and may also have you get an imaging test. Depending on your diagnosis, treatment may include the RICE method, medication, and possibly surgery.
To help prevent knee instability, be sure to see your doctor as soon as possible if you start to have knee related symptoms. You can also try knee strengthening exercises and avoid overusing your knee.
27 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Gupte C, St. Mart JP.The acute swollen knee: diagnosis and management.J R Soc Med. 2013;106(7):259-68. doi:10.1177/0141076813482831Cleveland Clinic.Patellar instability.Nevitt, M., Tolstykh, I., Shakoor, N. et al.Symptoms of knee instability as risk factors for recurrent falls.Arthritis Care and Research. 2016. 68(8):1089-1097. doi:10.1002/acr.22811Johns Hopkins Medicine.Arthritis? Joint symptoms you can’t ignore (and ones you can).Cleveland Clinic.Knee ligaments.Cleveland Clinic.ACL (anterior cruciate ligament) tear.Cleveland Clinic.Posterior cruciate ligament (pcl) injury.American Academy of Orthopaedic Surgeons.Collateral ligament injuries.Cleveland Clinic.Meniscal transplantation.Cleveland Clinic.When is knee surgery for a meniscus tear your best option?Johns Hopkins Medicine.Patellar instability.Lee PYF, Nixion A, Chandratreya A, Murray JM.Synovial plica syndrome of the knee: a commonly overlooked cause of anterior knee pain.Surg J (N Y). 2017;3(1):e9-e16. doi:10.1055/s-0037-1598047American Academy of Orthopaedic Surgeons.Arthritis of the knee.MedlinePlus.Femoral nerve dysfunction.Güner S, Hagharı S, Inanıcı F, Alsancak S, Aytekın G.Knee muscle strength in multiple sclerosis: relationship with gait characteristics.J Phys Ther Sci. 2015;27(3):809-813. doi:10.1589/jpts.27.809Michigan Medicine.Knee problems and injuries.Lee JW, Kang SH, Choi HG.Analysis of the associations between arthritis and fall histories in korean adults.IJERPH. 2021;18(7):3758. doi:10.3390/ijerph18073758Matsumoto H, Okuno M, Nakamura T, Yamamoto K, Hagino H.Fall incidence and risk factors in patients after total knee arthroplasty.Arch Orthop Trauma Surg. 2012;132(4):555-563. doi:10.1007/s00402-011-1418-yJohns Hopkins Medicine.Knee pain and problems.Cedars Sinai.Word: crepitus.Johns Hopkins Medicine.Knee pain and problems.Michigan Medicine.Rest, ice, compression, and elevation (rice).Johns Hopkins Medicine.Knee replacement surgery procedure.The Orthopedic Institute of New Jersey.5 acl injury prevention exercises.Orthopedic Associates.How helpful is using a knee brace?Johns Hopkins Medicine.Overuse injuries.Centers for Disease Control and Prevention.Facts about seat belt use.
27 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Gupte C, St. Mart JP.The acute swollen knee: diagnosis and management.J R Soc Med. 2013;106(7):259-68. doi:10.1177/0141076813482831Cleveland Clinic.Patellar instability.Nevitt, M., Tolstykh, I., Shakoor, N. et al.Symptoms of knee instability as risk factors for recurrent falls.Arthritis Care and Research. 2016. 68(8):1089-1097. doi:10.1002/acr.22811Johns Hopkins Medicine.Arthritis? Joint symptoms you can’t ignore (and ones you can).Cleveland Clinic.Knee ligaments.Cleveland Clinic.ACL (anterior cruciate ligament) tear.Cleveland Clinic.Posterior cruciate ligament (pcl) injury.American Academy of Orthopaedic Surgeons.Collateral ligament injuries.Cleveland Clinic.Meniscal transplantation.Cleveland Clinic.When is knee surgery for a meniscus tear your best option?Johns Hopkins Medicine.Patellar instability.Lee PYF, Nixion A, Chandratreya A, Murray JM.Synovial plica syndrome of the knee: a commonly overlooked cause of anterior knee pain.Surg J (N Y). 2017;3(1):e9-e16. doi:10.1055/s-0037-1598047American Academy of Orthopaedic Surgeons.Arthritis of the knee.MedlinePlus.Femoral nerve dysfunction.Güner S, Hagharı S, Inanıcı F, Alsancak S, Aytekın G.Knee muscle strength in multiple sclerosis: relationship with gait characteristics.J Phys Ther Sci. 2015;27(3):809-813. doi:10.1589/jpts.27.809Michigan Medicine.Knee problems and injuries.Lee JW, Kang SH, Choi HG.Analysis of the associations between arthritis and fall histories in korean adults.IJERPH. 2021;18(7):3758. doi:10.3390/ijerph18073758Matsumoto H, Okuno M, Nakamura T, Yamamoto K, Hagino H.Fall incidence and risk factors in patients after total knee arthroplasty.Arch Orthop Trauma Surg. 2012;132(4):555-563. doi:10.1007/s00402-011-1418-yJohns Hopkins Medicine.Knee pain and problems.Cedars Sinai.Word: crepitus.Johns Hopkins Medicine.Knee pain and problems.Michigan Medicine.Rest, ice, compression, and elevation (rice).Johns Hopkins Medicine.Knee replacement surgery procedure.The Orthopedic Institute of New Jersey.5 acl injury prevention exercises.Orthopedic Associates.How helpful is using a knee brace?Johns Hopkins Medicine.Overuse injuries.Centers for Disease Control and Prevention.Facts about seat belt use.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Gupte C, St. Mart JP.The acute swollen knee: diagnosis and management.J R Soc Med. 2013;106(7):259-68. doi:10.1177/0141076813482831Cleveland Clinic.Patellar instability.Nevitt, M., Tolstykh, I., Shakoor, N. et al.Symptoms of knee instability as risk factors for recurrent falls.Arthritis Care and Research. 2016. 68(8):1089-1097. doi:10.1002/acr.22811Johns Hopkins Medicine.Arthritis? Joint symptoms you can’t ignore (and ones you can).Cleveland Clinic.Knee ligaments.Cleveland Clinic.ACL (anterior cruciate ligament) tear.Cleveland Clinic.Posterior cruciate ligament (pcl) injury.American Academy of Orthopaedic Surgeons.Collateral ligament injuries.Cleveland Clinic.Meniscal transplantation.Cleveland Clinic.When is knee surgery for a meniscus tear your best option?Johns Hopkins Medicine.Patellar instability.Lee PYF, Nixion A, Chandratreya A, Murray JM.Synovial plica syndrome of the knee: a commonly overlooked cause of anterior knee pain.Surg J (N Y). 2017;3(1):e9-e16. doi:10.1055/s-0037-1598047American Academy of Orthopaedic Surgeons.Arthritis of the knee.MedlinePlus.Femoral nerve dysfunction.Güner S, Hagharı S, Inanıcı F, Alsancak S, Aytekın G.Knee muscle strength in multiple sclerosis: relationship with gait characteristics.J Phys Ther Sci. 2015;27(3):809-813. doi:10.1589/jpts.27.809Michigan Medicine.Knee problems and injuries.Lee JW, Kang SH, Choi HG.Analysis of the associations between arthritis and fall histories in korean adults.IJERPH. 2021;18(7):3758. doi:10.3390/ijerph18073758Matsumoto H, Okuno M, Nakamura T, Yamamoto K, Hagino H.Fall incidence and risk factors in patients after total knee arthroplasty.Arch Orthop Trauma Surg. 2012;132(4):555-563. doi:10.1007/s00402-011-1418-yJohns Hopkins Medicine.Knee pain and problems.Cedars Sinai.Word: crepitus.Johns Hopkins Medicine.Knee pain and problems.Michigan Medicine.Rest, ice, compression, and elevation (rice).Johns Hopkins Medicine.Knee replacement surgery procedure.The Orthopedic Institute of New Jersey.5 acl injury prevention exercises.Orthopedic Associates.How helpful is using a knee brace?Johns Hopkins Medicine.Overuse injuries.Centers for Disease Control and Prevention.Facts about seat belt use.
Gupte C, St. Mart JP.The acute swollen knee: diagnosis and management.J R Soc Med. 2013;106(7):259-68. doi:10.1177/0141076813482831
Cleveland Clinic.Patellar instability.
Nevitt, M., Tolstykh, I., Shakoor, N. et al.Symptoms of knee instability as risk factors for recurrent falls.Arthritis Care and Research. 2016. 68(8):1089-1097. doi:10.1002/acr.22811
Johns Hopkins Medicine.Arthritis? Joint symptoms you can’t ignore (and ones you can).
Cleveland Clinic.Knee ligaments.
Cleveland Clinic.ACL (anterior cruciate ligament) tear.
Cleveland Clinic.Posterior cruciate ligament (pcl) injury.
American Academy of Orthopaedic Surgeons.Collateral ligament injuries.
Cleveland Clinic.Meniscal transplantation.
Cleveland Clinic.When is knee surgery for a meniscus tear your best option?
Johns Hopkins Medicine.Patellar instability.
Lee PYF, Nixion A, Chandratreya A, Murray JM.Synovial plica syndrome of the knee: a commonly overlooked cause of anterior knee pain.Surg J (N Y). 2017;3(1):e9-e16. doi:10.1055/s-0037-1598047
American Academy of Orthopaedic Surgeons.Arthritis of the knee.
MedlinePlus.Femoral nerve dysfunction.
Güner S, Hagharı S, Inanıcı F, Alsancak S, Aytekın G.Knee muscle strength in multiple sclerosis: relationship with gait characteristics.J Phys Ther Sci. 2015;27(3):809-813. doi:10.1589/jpts.27.809
Michigan Medicine.Knee problems and injuries.
Lee JW, Kang SH, Choi HG.Analysis of the associations between arthritis and fall histories in korean adults.IJERPH. 2021;18(7):3758. doi:10.3390/ijerph18073758
Matsumoto H, Okuno M, Nakamura T, Yamamoto K, Hagino H.Fall incidence and risk factors in patients after total knee arthroplasty.Arch Orthop Trauma Surg. 2012;132(4):555-563. doi:10.1007/s00402-011-1418-y
Johns Hopkins Medicine.Knee pain and problems.
Cedars Sinai.Word: crepitus.
Michigan Medicine.Rest, ice, compression, and elevation (rice).
Johns Hopkins Medicine.Knee replacement surgery procedure.
The Orthopedic Institute of New Jersey.5 acl injury prevention exercises.
Orthopedic Associates.How helpful is using a knee brace?
Johns Hopkins Medicine.Overuse injuries.
Centers for Disease Control and Prevention.Facts about seat belt use.
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