Knee Instability: What You Need To Know - Brace Direct

Knee Instability: What You Need To Know

Chronic knee instability is when you feel the knee gives away under your weight. Patients complain of the knee twisting when or feeling unstable performing any activity that puts slight pressure on the knee, like exiting a car. . Multiple causes can lead to an unstable knee. 

Knee abnormality is highly prevalent in sportspeople and players. Per reports, knee instability has a prevalence of around 22% in athletes. 

Women are more prone to developing knee instability than men due to wider hips. 

This article will serve as a comprehensive overview of all you need to know about knee instability. Read on to learn more!


man sitting on bleachers holding knee in pain

The main reason for the wear and tear of the cruciate ligaments is trauma. Sports injuries make up a significant part of knee instability cases. 

Sports injuries involve sudden twisting of the knee. Frisbee and tennis players can experience excessive stretching and twisting of the knee ligaments leading to chronic instability. 

Roadside accidents can also damage the knee ligaments and make them unstable.

Genetics and pre-existing conditions can also put you at risk of knee instability.

There are many potential causes of knee instability, as discussed below:

Patellar Instability 

Your kneecap (patella) sits perfectly in the trochlear groove. Patellar instability involves the shifting of the kneecap out of place. 

Patellar instability can be the result of anatomical deformities. Weak muscles and a torn patellofemoral ligament due to traumatic injury can also contribute to patellar instability. 

Research suggests that patellar instability is a common cause of knee discomfort and disability. The patella's typical "giving way" makes it hard to move.

Symptoms of kneecap shifting under pressure include soreness and swelling in the knee region. Pain reduces the range of motion too. 

Damage to Knee Ligaments

xray of knee joint showing knee damage

Your knee joint is held together by various ligaments. Ligaments are connective tissues that play a crucial role in allowing knee joint movement and rotation during walking, jumping, and stretching. 

Injury to the knee ligaments, like a tear or rupture, can lead to knee instability.

Anterior Cruciate Ligament (ACL) 

The anterior cruciate ligament, or ACL, is a tendon that connects the leg and the thigh bones, i.e., the femur to the tibia. 

Sharp injury or straining of the knee joint can tear the soft tissue. It most commonly occurs in athletes. 

A study highlighted the role played by the anterior cruciate ligament in the knee's stability. Surgical correction is of pivotal importance in treating ACL injury-induced knee instability.

Improper treatment of ACL injuries in active youngsters can lead to knee instability and degeneration.

Medial Cruciate Ligament (MCL)

Injury to the medial cruciate ligament (MCL) can trigger chronic instability of the knee. This ligament extending on the knee's downside prevents excessive knee joint rotation. 

MCL injuries contribute to anteromedial instability of the knee. Injury to this ligament is often due to direct impact to the knee and can be treated without surgery.

Posterior Cruciate Ligament (PCL)

The posterior cruciate ligament (PCL) also stabilizes your knee joint. The primary purpose of this ligament is to stop the knee from sliding too far backward. Excessive rotation of the knee can trigger PCL tears and subsequent knee instability.

Injuries to the PCL are often referred to as dashboard injuries because they occur due to direct blows or trauma to the knee joint, like during a car accident or a fall.

Knee Osteoarthritis

older couple walking through park with bicycle

Osteoarthritis (OA) of the knee is a degenerative joint disease common in old age people. The disorder causes the knee joint (s) to wear down, leading to pain and inflammation. 

It can make your knee unstable and wobble. The prevalence of knee instability in knee patients was 44%. The instability was felt during daily activities. 

Functional decline in knee OA patients hinders them from putting weight on the knee. There are numerous self-reported cases of knee instability in OA patients.

The findings of a study suggest that senile people suffering from knee OA experience episodes of knee instability. The instability is associated with gait issues.

Risk Groups for Knee Instability 

Based on the potential causes of knee instability, there are certain risk groups identified for knee instability. 

It includes young people like athletes, players (basketball, rugby, etc.), dancers, and manual laborers. 

Individuals with a family history of osteoarthritis also have a greater risk of falling prey to instabilities, especially old-aged people. 

Obese people are also at a higher risk of instability, as the additional weight places extra pressure on the knee joint.


doctor examining injured knee

Knee instability can present as several mild to severe symptoms as follows:


According to a study, knee instability is associated with pain and activity limitations. Those with knee instability typically experience bursts of mild, moderate, or severe pain. 

Pain frequently arises during twisting movements. The majority of patellar instability patients feel anterior knee pain.


An evident symptom of knee instability is muscle weakness. You may find yourself incapable of twisting and freely moving your knee. Chronic knee weakness is present in almost all cases of knee instability.

Inability to Straighten the Knee 

woman holding knee in pain

Knee pain and weakness are often accompanied by an inability to straighten the knee due to constant pain restricting movement. 

The ligaments are responsible for bending and straightening the knee, so the restrictions in the movement are understandable. 

Pop Sound

A "pop" sound indicates an underlying ACL injury. Filling of the fluid in the knee (effusion) and pop sound are significant events in cases of trauma to the knee. The symptoms show up within two hours of injury.

Authentic studies show that chronic instabilities like knee instability have mechanical symptoms such as:

  • Catching¬†
  • Clicking¬†
  • Locking¬†
  • Giving away

The symptoms are felt during twisting movements of the knee. The popping sound and other symptoms add to the disability of the patients who fear bearing weight on the knee. 

You should consult a doctor if the symptoms last more than 72 hours after injury.


During your visit, the doctor will physically examine the knee. That comprises looking for popping for licking sounds and evaluating the extent of knee movement (restrictions). 

They might ask you for any underlying bone conditions, such as OA or rheumatoid arthritis, and your history of injury or trauma. 

For a proper diagnosis, you might have to undergo some tests, including the Lachman testor pivot shift test. 

Your orthopedic doctor may use radiographic images to check for soft tissue damage. MRI scans and X-rays aid in pointing out ligament injuries. 3D CT scans are used for better scanning of the knee joint. 

Knee instability is often associated with gait disturbances (especially in knee OA patients). Therefore, a gait lab analysis may also be undertaken to diagnose the disorder. 


Mild cases of knee instability are treated with non-interventional therapies. However, severe cases of ligament tears require surgical treatment.

RICE approach 

woman holding ice on a knee injury

Mild to moderate instability cases can be treated with home remedies. Adopting the RICE approach can help effectively manage swollen and painful knee ligaments in unstable knees. Rest, ice, compression, and elevation are effective methods. 

Rest allows the ligaments to heal and prevents further twisting and damaging of the knee structures.  

Ice application several times a day is a good way of alleviating inflammation and swelling. Cryotherapy has shown promising results in reducing effusion/edema in the injured ligaments. Studies show that the strategy effectively reduces ligament injury patients' symptoms.e

Compression of the knee joint pushes out the accumulated fluid in the knee joint. However, you should consult your physician before applying compression. 

Elevating the knee above heart level can increase the fluid drainage from your joint. That allows rapid healing of the soft tissues. 


person taking medication

Over-the-counter painkillers can offer pain relief. Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, diclofenac sodium, and naproxen sodium help reduce inflammation and instability-related pain.

Your doctor may also prescribe muscle relaxants to ease the pain and help you sleep better. 

Knee Braces 

Protecting your knee joint can help alleviate the symptoms and aid in healing the instability by immobilizing it. Using knee braces is the prevalent way of providing additional support to the knee muscles and ligaments while preventing further injury.

A study highlighted that knee bracing could reduce pain and improve joint stabilization.

Another study concluded knee braces reduce pain and dynamic instability in knee OA patients. Using a soft knee brace improves movement and boosts the confidence of old patients with knee instability.

A 2018 study revealed that wearing of soft knee brace evidently reduces the objectively assessed dynamic knee instability among OA patients. You can choose between a non-tight or a tight brace. 

The same study concluded that both types (tight and non-tight) have the same results in stabilizing the knee. 

Valgus knee bracing (muscle braces) and gait modification can improve the quality of life in knee instability patients. 

Physical Therapy 

physical therapist working on an injured knee

The main aim of physical therapy is to increase the strength and mobility of the joint muscles/ ligaments. There are multiple benefits of physical therapy for knee instability. 

According to a randomized controlled trial, physiotherapy helped restore knee stability and reduce pain. Your physiotherapist will devise specialized knee joint stabilization training programs to help you move and do daily chores easily. The program is usually paired with strengthening and functional exercises. 

Individuals with isolated MCL tears are normally treated with bracing and physical therapy. The combination of treatment modalities provides outstanding results.

Knee Ligament Surgery 

For extensive ligament or bone injuries, you might have to undergo surgery for correction. Injury to the ACL is the most common cause of knee instability. Therefore, ACL reconstruction is the most effective surgical method of regaining stabilization of the knee. 

Mild MCL injuries are managed well with nonoperative methods. However, severe (grade 3 MCL) injuries require operative repair and surgical reconstruction.

Recover takes about three to six months, and you might have to use crutches for up to two months.