Weak In The Knees: Top 8 Reasons You Must Know

Are you feeling weak in the knees? Or are you also facing difficulties getting up and sitting down and are worried about it? Don’t worry; we have got you covered. Here are some things you must know when your knees start giving out.

1. Anatomy of The Knees

The knee is one of the most important, largest, and most complex joints of the human body. Bones forming the knee joint are the femur or the thigh bone, the Tibia or the shin bone, and the patella¹ or the kneecap.

These three bones come in contact with one another, forming two sub-joints: the Tibiofemoral and Patellofemoral joints. The knee has several structures like the ligaments, capsule, meniscus, bursae, cartilages, tendons, and muscles.

This complex structure makes this site most vulnerable, leading to its frequent weakness frequently.

2. What Exactly Do We Mean by Weak in the Knees?

Weak in the knees does not have a specific definition. It is a vague term.

It is an idiom that means feeling unsteady or about to faint, usually due to emotional reasons such as excitement, nervousness, or attraction. The phrase is used to describe a physical manifestation of intense feelings that make someone feel unstable or unable to stand firmly.

It happens when the knees give out and do not function normally. When a person presents with symptoms that interfere with daily activities -like pain or difficulty in walking- they are weak in the knees.

3. Typical Weak Knee Symptoms

• Pain
• Swelling
• Difficulty in weight-bearing
• Difficulty in walking
• Inflammation
• Stiffness of the knee
• Redness
• Burning or prickling sensation
• Instability
• Difficulty in transitions like sitting to stand or stand to sit positions
• Crepitus-a popping noise heard when the knee is bent
• Inability to straighten the knee
• Difficulty in performing activities of daily living

Once someone starts becoming weak in the knees, all these symptoms come into the picture. 

4. Basic Terminologies

Before we discuss further the causes and management of knee weakness, let’s get familiar with some basic terminologies that will help us understand better.

a) Ligaments – Ligaments are bands of tough elastic tissue that connect one bone to another, support the joints, and prevent the joints’ hypermobility. The knee complex has 11 ligaments in all.

b) Joint capsule – It is a dense fibrous connective tissue attached to the bones, forming a sleeve around the knee that seals the joint space, forms an articular surface, and provides stability.

c) Bursae – These are small fluid-filled sacs lying near joints and other bony prominences. They reduce friction and improve lubrication between the bones. As many as 12 bursae are present in the knee complex.

d) Menisci – These are crescent-shaped, fibrocartilaginous structures sitting between the knees. They reduce friction and disperse the weight of the body.

5. What Causes the Knees to be Weak?

Several factors are responsible for alteration in the biomechanism of the knee, leading to pain and weakness:

5.1 Aging

This is the most commonly known underlying cause of weakened knees. As age increases, degenerative changes in joints take place. Joints become stiff and less flexible as the ligaments shorten. Synovial fluid decreases, leading to increased friction, which causes erosion of the bony ends, resulting in weakening.

5.2 Gender

When we speak about gender, we know that women are more prone to weakening their knees as compared to men. This is because of the difference in the female biomechanics owing to pregnancies. Also, women have comparatively smaller cartilaginous volumes and different gait patterns compared to men.

5.3 Sports Injuries

Sports injuries are the major causes of the weakening of the knee complex as these injuries cause damage to the supporting structures. Fall, twisting of the legs, a direct blow by the competitors, or the ball cause injuries leading to weakening of the knee, discomfort, and other symptoms. The quality and severity of trauma determine the severity of injury and discomfort.

5.4 Ligamentous Injuries

Out of the 11 ligaments around the knee, four ligaments play a major role in the mobilization as well as stabilization of the knee, these being the Anterior and Posterior Cruciate ligaments ²and the Medial and Lateral Collateral ligaments. The type of ligamentous injury depends upon the direction of the force and its severity.

The ligaments may tear at either of its attachments which is either the origin or the insertion. Sometimes, it may also take a chip of bone from its attachment. The rupture may vary from a few fibers to a complete tear, depending on the severity of the trauma.

Pain and swelling are significant symptoms of ligament tears. Also, there is an increase or decrease in the angulation of the knee depending on which ligament is injured.

5.5 Meniscal Injuries

Meniscal injury takes place when a person is standing half-bent and with the body twisted to one side. The meniscus is ripped off during this motion due to rotation between the two bony articulations. Pain, swelling, and locking of the knee are the presenting features.

5.6 Arthritis

Arthritis is a degenerative disease occurring in the elderly, usually bilaterally. The presenting clinical features are pain, swelling, stiffness, crepitus, cramping, and weakness.

Arthritis is a term used to describe a group of over 100 medical conditions that affect the joints, causing pain, stiffness, and swelling. It is a common condition, especially among older adults, and can affect people of all ages, genders, and races.

There are several types of arthritis, including osteoarthritis, rheumatoid arthritis, psoriatic arthritis, and gout. Symptoms of arthritis can range from mild to severe and can impact daily activities and quality of life. Treatment for arthritis typically involves a combination of medications, physical therapy, and lifestyle changes. In severe cases, surgery may be necessary.

5.7 Metabolic Bone Diseases

Metabolic bone diseases are a group of conditions that affect the bones and how they function. These diseases result from abnormal metabolism, which is the way the body processes food and other substances to produce energy and maintain healthy tissues and organs.

Some common examples of metabolic bone diseases include osteoporosis, osteomalacia³, Paget’s disease, and rickets. These conditions can lead to decreased bone density, weakened bones, and an increased risk of fractures.

Symptoms can vary depending on the specific disease but may include pain, fractures, joint deformities, and difficulty walking.

Treatment for metabolic bone diseases typically involves medications to strengthen bones, supplements to replace missing nutrients, and lifestyle changes to improve bone health. In severe cases, surgery may be necessary.

Following are some of the metabolic bone diseases that cause people to be weak in the knees:

• Osteoporosis (reduced bone density)
• Rickets (vitamin D deficiency)
• Osteomalacia (softening of bones)

5.8 Infection of the Bones

An infection of the bones, also known as osteomyelitis, is a serious condition that occurs when bacteria, fungi, or other microorganisms invade the bone tissue and cause inflammation and damage.

The infection can spread to the bone from an adjacent area, such as the skin or bloodstream, or it can be the result of a direct injury to the bone. Symptoms of bone infection may include fever, pain and swelling in the affected area, redness, and warmth.

The diagnosis of bone infection is typically made through a combination of medical history, physical examination, imaging tests (such as X-rays, CT scans, or MRI), and blood tests.

Treatment for bone infection typically involves antibiotics to eliminate the infection and surgery to remove any dead or damaged bone tissue. In some cases, an infected bone may need to be replaced with a bone graft or artificial implant.

Osteomyelitis and myelitis are infections that make the knees weak.

Other causes include-

• Sedentary lifestyle
• Overuse
• Increased body weight
• Trauma like road traffic accidents, fall, or direct blow over the knees
• Muscles weakness- hamstrings or quadriceps weakening
• Bursitis
• Sprains
• Strains
• Torn cartilage or ligament
• Bone tumors

6. How to Treat Weak Knees?

Before treatment, we need to properly diagnose the pathology ⁴that is leading to weak knees.

Investigations to be carried out to rule out weak in the knees are:

• X-Ray
• Bone scan
• Computed Tomography
• Bone biopsies
• Magnetic resonance imaging
• Blood tests
• Bone density tests

6.1 Treatment of Weak Knees

Treatment for weak knees depends on the underlying cause. Here are some common approaches:

1. Physical therapy: Physical therapy can help improve the strength and flexibility of the knee joint, reducing knee weakness and improving overall function.

2. Medications: Over-the-counter pain relievers and anti-inflammatory medications can help reduce pain and swelling in the knee.

3. Injections: Corticosteroid injections can help reduce pain and swelling, while hyaluronic acid injections can help lubricate the knee joint and improve mobility.

4. Bracing or assistive devices: Wearing a knee brace or using a cane or crutches can help reduce stress on the knee and improve stability.

5. Lifestyle changes: Maintaining a healthy weight, engaging in regular exercise, and avoiding high-impact activities can help reduce stress on the knee and improve overall knee health.

6. Surgery: In severe cases, surgery may be necessary to repair or replace damaged knee structures.

7. Strengthening Exercises:

   • Straight and side leg raises
   • Prone leg raises
   • Full squats
   • Half squats
   • Step exercises
   • Knee bends

It is important to consult a doctor for a proper diagnosis and individualized treatment plan for weak knees.

7. Conclusion

In a nutshell, weak knees reduce the quality of life and keep the patient feeling nervous and agitated due to pain and dependence on others for walking and other daily activities.

Care should be taken beforehand by practicing a healthy lifestyle and keeping oneself physically active, As we all know: Prevention is better than cure!

Reviewed by: Omejua Chimdike (B.MLS), Biomedical Scientist (UNN)

About Omejua Chimdike .G.

A talented, knowledgeable, and certified medical laboratory scientist with experience in carrying out standard laboratory practices (tests) on patients of various cultural backgrounds with the aim of researching and developing diagnostic approaches that will aid in the diagnosis of diseases and increase patient outcomes to treatment. Currently, working as a research scientist at Everight Diagnostic Laboratory Services Limited (Centre for Research and Molecular Studies), Nigeria.

LinkedIn: https://www.linkedin.com/in/chimdike-omejua-520859199

WordPress: https://omejuachimdikeacademia.wordpress.com/

Gmail: chimdike.omejua.188155@unn.edu.ng

Frequently Asked Questions (FAQs) 

1. What Makes Men Go Weak in the Knees? 

It is a figurative expression used to describe a feeling of emotional instability or unsteadiness, often due to intense feelings such as excitement, nervousness, or attraction. Men can experience these feelings just like anyone else and they may also describe themselves as “weak in the knees” in these situations. It’s a way of expressing a physical manifestation of intense emotions and should not be taken literally.

2. Why Do My Knees Feel Weak After Doing Exercise?

Knees feeling weak after exercise can be caused by several factors, including:

1. Fatigue: Engaging in intense physical activity can cause muscle fatigue, which can make your knees feel weak or unsteady.

2. Dehydration: Dehydration can cause electrolyte imbalances, leading to muscle weakness and unsteadiness, including in the knees.

3. Muscle strain or injury: Overusing or overloading the knee muscles can lead to strain or injury, causing knee weakness or instability.

4. Arthritis: Knee pain and weakness can be symptoms of arthritis, a condition that affects the joints and causes inflammation and damage.

5. Poor posture or alignment: Poor posture or misalignment of the legs and hips can put extra stress on the knee joints, leading to weakness and instability.

If your knee weakness persists after exercise or is accompanied by other symptoms, such as pain, swelling, or redness, it is important to consult a doctor for a proper evaluation and treatment. In some cases, physical therapy or other forms of rehabilitation may be necessary to improve knee strength and stability.

3. What is the Diagnosis of Feeling Weak in the Knees After Squats?

Feeling that after squats can have several possible causes, including:

1. Muscle fatigue: Engaging in intense physical activity, such as squats, can cause muscle fatigue, which can make your knees feel weak or unsteady.

2. Poor form or technique: Incorrect form or technique while performing squats can put extra stress on the knee joints, leading to weakness or instability.

3. Knee injury: Overloading or overusing the knee joints can lead to injury, causing knee pain and weakness.

4. Arthritis: Knee pain and weakness can be symptoms of arthritis, a condition that affects the joints and causes inflammation and damage.

5. Neurological conditions: In some cases, knee weakness may be a symptom of a neurological condition, such as peripheral neuropathy, that affects the nerves that control the muscles in the legs.

A proper diagnosis of the cause of knee weakness after squats can be made through a combination of medical histories, physical examination, and imaging tests, such as X-rays or MRIs⁵. If knee weakness persists after squats or is accompanied by other symptoms, such as pain, swelling, or redness, it is important to consult a doctor for a proper evaluation and treatment. In some cases, physical therapy or other forms of rehabilitation may be necessary to improve knee strength and stability.

4. What Would Cause Extreme Knee Weakness After Weight Loss?

Extreme knee weakness after weight loss can have several possible causes, including:

1. Muscle wasting: Rapid weight loss can cause muscle wasting, leading to weakness in the legs, including the knees.

2. Vitamin and mineral deficiencies: Certain vitamins and minerals, such as calcium and vitamin D, are important for maintaining healthy bones and muscles. Deficiencies in these nutrients can cause muscle weakness, including in the knees.

3. Dehydration: Dehydration can cause electrolyte imbalances, leading to muscle weakness and unsteadiness, including in the knees.

4. Hormonal changes: Hormonal changes that occur with rapid weight loss can affect muscle mass and strength, leading to knee weakness.

5. Knee injury: Sudden weight loss can increase the stress on the knee joints, leading to injury and knee pain and weakness.

If you are experiencing knee weakness after rapid weight loss, it is important to consult a doctor for a proper evaluation and treatment. In some cases, dietary changes, vitamin and mineral supplements, or physical therapy may be necessary to improve knee strength and stability.

1. Hargett, Damayea I., Brent R. Sanderson, and Milton TM Little. “Patella fractures: approach to treatment.” JAAOS-Journal of the American Academy of Orthopaedic Surgeons 29.6 (2021): 244-253. ↩︎
2. Lynch, Thomas B., Jorge Chahla, and Clayton W. Nuelle. “Anatomy and biomechanics of the posterior cruciate ligament.” The Journal of Knee Surgery 34.05 (2021): 499-508. ↩︎
3. Florenzano, Pablo, et al. “Tumor-induced osteomalacia.” Calcified Tissue International 108 (2021): 128-142. ↩︎
4. Vorobjeva, N. V., and B. V. Chernyak. “NETosis: molecular mechanisms, role in physiology and pathology.” Biochemistry (Moscow) 85 (2020): 1178-1190. ↩︎
5. Wald, Lawrence L., et al. “Low‐cost and portable MRI.” Journal of Magnetic Resonance Imaging 52.3 (2020): 686-696. ↩︎

Last Updated on March 9, 2024 by Suchi