Weak In The Knees: Top 8 Reasons You Must Know

Photo by Terry Shultz on Unsplash/Copyright 2021

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.

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 -Femur or the thigh bone, Tibia or the shin bone, and the patella 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 weakness frequently.

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 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.

32089852 osteoarthitis of both knees
by Nawoot / unlimphotos

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. 

Before we discuss further the causes and management of knee weakness, let’s get familiar with some basic terminologies which 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.

36075184 sporty senior man
Source: By djoronimo/Unlimphotos photos/Copyright 2021

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.

What causes the knees to be weak?

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

1) Aging

This is the commonest 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.

2) Gender

When we speak about gender, we know that women are more prone to weakening the 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.

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.

4) Ligamentous Injuries

Out of the 11 ligaments around the knee, four ligaments play a major role in mobilization as well as stabilization of the knee, these being the Anterior and Posterior Cruciate ligaments and 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 attachment 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 the 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) 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.

16562904 woman and hologram with knee radiography
Source: by videodoctor, Unlimphotos/Copyright 2021

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.

7) Metabolic Bone Diseases

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)

8) Infection Of The Bones

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

How to treat weak knees?

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

Investigations to be carried out for ruling out weak in the knees are:

  • X-Ray
  • Bone scan
  • Computed Tomography
  • Bone biopsies
  • Magnetic resonance imaging
  • Blood tests
  • Bone density tests
24768920 human anatomy with visible skeleton and muscles
Source: by kentoh, Unlimphotos/Copyright 2021

Treatment of weak knees is mainly physiotherapy and exercise-based.

  • Icing and elevation reduce joint pain
  • Rest as much as you can
  • Proper diet to reduce weight (as suggested by the physician)
  • Prevent re-injury
  • Medications- painkillers like non-steroidal anti-inflammatory drugs and antibiotics
  • Bracing
  • Proper footwear
  • Compression sleeves
  • Surgeries – Replacement Surgeries or Osteotomies (depending on the condition and the physician). 


You can do Strengthening Exercises Like-

  1. Straight and side leg raises
  2. Prone leg raises
  3. Full squats
  4. Half squats
  5. Step exercises
  6. Knee bends

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



While at times contributed by guest authors, our content is medically reviewed periodically by professionals for accuracy and relevance. We pride ourselves on our high-quality content and strive towards offering expertise while being authoritative. Our reviewers include doctors, nurses, mental health professionals, and even medical students. 

Do note that any information found on the site does not constitute legal or medical advice. Should you face health issues, please visit your doctor to get yourself diagnosed. Icy Health offers expert opinions and advice for informational purposes only. This is not a substitute for professional medical advice.


Please enter your comment!
Please enter your name here