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Pulled muscle in knee cap: Knee Strain or Sprain | Orthopedics

Knee Strain or Sprain | Orthopedics

What is a knee strain or sprain?

A knee strain occurs when a muscle or tendon is torn or stretched. The tendons are fibrous cords that connect muscles to bones.

A knee sprain occurs when the ligaments in the knee joint stretch or tear. Ligaments connect the bones of your lower leg to the bones in your thigh together in your knee joints.

Common related conditions

Anterior Cruciate Ligament (ACL) Injury
Lateral Collateral Ligament (LCL) Injury
Medial Collateral Ligament (MCL) Injury
Posterior Cruciate Ligament (PCL) Injury

Causes of a knee strain or sprain

  • Injuries — trauma, sports injuries or falls that overstretch the joints and soft tissue that surround the knee and cause a knee sprain or strain.
  • Overuse — building up too quickly in a sport, such as running, can overwhelm the body and lead to knee strains or sprains.
  • Muscle weakness — muscles that can’t support the knee joints can cause a knee strain or sprain.
  • Reduced flexibility — tight muscles can restrict joint motion and lead to functional weaknesses at the knee joint to cause a knee strain or sprain.
  • Running form — overpronating when running or walking can increase stress to the knee and cause a knee strain or sprain.

Risk factors for a knee strain or sprain

  • Contact sports — participating in contact sports such as football, basketball and soccer put you at a higher risk for knee sprains or strains.
  • Prior knee strains or sprains — prior sprains or strains to the knee make you more likely to suffer another knee sprain or strain.
  • Improper footwear — wearing improper footwear can put additional pressure on the knee joint and cause a knee strain or sprain.

Symptoms of a knee strain or sprain

  • Pain and tenderness in the knee
  • Stiffness, bruising and swelling in the knee
  • Instability when walking
  • Popping noise when injured

Diagnosis of a knee strain or sprain

Diagnosing a knee sprain or strain is challenging due to the complexity of the knee. Your physician will perform a variety of physical tests, as well as take a full medical history, to determine the exact cause and location of the injury.

A patient could have multiple knee injuries at one time, so your doctor may order an x-ray or MRI. These imaging modalities will be able to identify what is causing the symptoms and help the provider determine the best treatment for your case.

Treatment for a knee strain or sprain

Many patients can self-treat knee strain or sprain with rest, ice, compression, elevation and anti-inflammatory medication. If the pain is moderate to severe, your physician may require you to wear a brace over the knee to provide stability. More advanced knee strains or sprains can be treated with the following treatments:

  • Physical therapy and rehabilitation — physical therapy is crucial to help strengthen the knee after a strain or sprain; your physical therapist will work with you to gradually add exercises that will help restore mobility in the knee.
  • PRP therapy (Platelet-rich plasma) — PRP therapy for knee strains or sprains is a newer therapy where your orthopedic physician will remove a blood sample from the patient, put the blood in a centrifuge to separate out the platelets (which contain growth factors that are important in healing injuries) and then inject them back into the patient at the affected site in the knee.

Recovery from a knee strain or sprain

It is important to work with your physician closely before you return to your everyday routine. When recovered, you should be able to perform simple exercises such as squatting, running, side to side motions and jumping without pain.

A mild sprain is healed after six weeks of resting and treating the knee. A severe strain or sprain can take as long as three to four months. The exact recovery time will depend on the treatment plan that your doctor and physical therapist recommend for you as well as the nature of the injury.

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Symptoms, causes, treatment options, and more

Knee strains are a common injury involving a torn muscle or tendon around the knee. Strains are often related to sports injuries.

According to a 2012 analysis, knee sprains and strains are the most common knee injuries seen in emergency rooms in the United States, accounting for 42.1% of cases.

This article explores the symptoms and possible causes of knee strains and sprains, along with available treatment options.

Knee strains affect the muscles or tendons.

The National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) state that they occur when a tendon or muscle stretches or tears. A tendon is a structure in the body that connects muscles to a bone.

A muscle strain around the knee is often due to overuse. The NIAMS indicate that a person may strain their knee from stressing the muscles, lifting heavy weights, or a sudden injury.

There are three grades of muscle strain based on severity.

They include:

  • Grade 1: A few muscle fibers are torn or stretched, and the muscle retains full strength.
  • Grade 2: This involves more muscle fibers being stretched and torn. The muscle becomes weaker and is more painful.
  • Grade 3: The most severe type of strain involving significant or complete tearing of the muscle or tendon, which causes loss of function.

There are several potential symptoms of a knee strain. According to the NIAMS, they commonly include:

  • cramping in the muscles around the knee
  • spasms in the muscles
  • swelling
  • bruising
  • difficulty with moving the muscles or walking

The severity of symptoms will vary according to the severity of the strain.

While strains affect the muscles and tendons, sprains affect the ligaments.

The NIAMS define a sprain as an injury to one or more ligaments from a stretch or tear. Ligaments are tough connective tissues linking bones to other bones.

There are four major ligaments of the knee joint. Of these, the anterior cruciate ligament (ACL) experiences the most injuries. A person can injure their ACL through contact, such as a football tackle, or without contact, which commonly occurs due to a sudden twisting motion.

Although both cause pain and swelling, knee sprain symptoms also often include difficulty putting weight on the leg, alongside pain with range of motion.

Learn more about sprains vs. strains here.

The most common causes of knee strains include:

  • twisting or lifting a heavy object without proper support
  • recent injury to the knee or muscle
  • overuse of the muscle

A tear to the tendons that run through the knee is a common sports injury.

According to the American Academy of Orthopaedic Surgeons (AAOS), two common tendon tears in the knee include a patellar tendon tear and a quadriceps tendon tear.

Common causes of tears to these tendons include:

  • landing awkwardly
  • direct force to the front of the knee
  • falling
  • misstepping and “jamming” the knee

Often, people can treat knee strains at home.

The NIAMS and AAOS recommend following the RICE method following a knee injury, which stands for:

  • Rest: May include using assistive walking devices to avoid moving or putting weight on the knee.
  • Ice: Wrap ice with a towel and apply to the knee to help reduce swelling.
  • Compression: This can involve using a wrap or specialized bandage to apply pressure to the knee.
  • Elevation: This can help reduce swelling.

Learn more about the RICE method here.

In addition to RICE, over-the-counter anti-inflammatory medications, such as acetaminophen or ibuprofen, may reduce pain and swelling.

It is always best to consult with a doctor if a person is unsure which medication to use, or if they take regular prescription medications.

Although people may need surgery for some knee injuries, a doctor may recommend several non-surgical treatments before discussing surgical options.

According to the AAOS, some common treatments may include:

  • physical therapy
  • immobilizing the knee with a brace
  • using crutches

If the knee strain or sprain is severe, surgery may be necessary to restore stability and function.

Recovery time varies greatly from person to person, according to the severity of the injury and whether they underwent an operation.

The United Kingdom’s National Health Service (NHS) note that people experiencing strains will feel better after 2 weeks. However, more severe injuries can take significantly longer.

Following a knee strain or sprain, a person should avoid strenuous exercise, such as running and jumping, until symptoms improve significantly. This recommendation is to avoid the risk of further damage.

The AAOS note the following recovery times for a tendon tear:

  • for mild cases, it can take 3–6 weeks to recover
  • after surgery, it can take 6 months to a year for complete recovery

Although a person can treat most minor knee sprains and strains at home, the AAOS recommend seeking immediate medical attention for a knee injury if people experience any of the following:

  • severe pain at the site
  • hearing or feeling a popping noise or sensation at the time of injury
  • limping
  • inability to move the knee
  • swelling at the injury site

A person should also seek medical attention if the pain or swelling gets worse, or if new symptoms develop. Always consult with a doctor if there is no improvement in symptoms following home treatment.

To diagnose a knee strain or sprain, a doctor will ask questions about a person’s symptoms, medical history, and if they participate in sport or similar activities.

They will then examine the knee and test for strength and range of motion, alongside other tests.

Healthcare professionals will usually obtain X-rays to check for broken bones. A doctor may also order an MRI to examine the tendons and ligaments of the knee.

Preventing a knee sprain or strain is not always possible, but there are ways to reduce the chances of sustaining injury.

The NIAMS recommend the following:

  • eating a healthful diet
  • maintaining a moderate weight
  • wearing properly-fitted shoes
  • avoiding exercising or playing sports when tired or in pain
  • running on flat surfaces
  • warming up and stretching before exercise
  • taking part in regular exercise
  • wearing protective equipment when playing sports

A knee strain occurs when a muscle or tendon stretches or tears. The severity of the strain can vary from mild to severe.

Mild cases often do not require medical attention, and a person can treat them at home.

More severe cases may require immobilization, physical therapy, or surgery. Recovery times can vary based on how severe the strain is and can range from several weeks to a year.

Sprain of the knee joint – symptoms, causes, treatment

This disease is treated by a neurologist.

Make an appointment


Sprain of the ligaments of the knee joint – damage to the structures of the ligamentous apparatus due to excessive physical or mechanical stress on the knee. According to the localization of the injured area, they are divided into stretching of the medial, lateral, anterior and posterior cruciate ligaments.

CMDT specialist tells

Kuchenkov A.V.

Orthopedist • Traumatologist • Surgeon • Phlebologist • Sports doctor • 25 years of experience

Publication date: May 11, 2021

Verification date: January 08, 2023

All facts have been verified by a doctor.

Contents of the article


    Symptoms of knee sprain

    Stages of development

    The pathological condition is divided into three degrees according to the severity of injuries:

    • Mild first degree – minimal manifestation of symptoms that disappear within the next two weeks
    • Medium second degree is characterized by difficulty in movement, pain, swelling. Damaged ligaments are not able to maintain the integrity of the joint
    • Severe third degree with complete or partial rupture of the ligaments. It occurs with severe pain, loss of joint stability. Accompanied by rupture of nerve fibers, blood vessels, bleeding into the articular cavity.

    More often, damage to several ligaments is diagnosed at the same time: injuries of the internal collateral plus anterior cruciate ligament, or external collateral with damage to the meniscus, tendons. This is due to the anatomically complex structure of the external lateral section.

    How to diagnose

    The doctor makes a preliminary diagnosis based on the patient’s complaints, visual examination, determination of injuries and their severity. Additionally assigned:

    • radiography to exclude a fracture
    • MRI is an informative method of layer-by-layer examination in different projections of all structures – ligaments, cartilage, tendons, soft tissues
    • ultrasound to detect inflammation, increase the volume of synovial fluid

    In some cases, arthroscopy is prescribed – an invasive, low-traumatic method for examining and treating sprains of the internal ligaments of the knee.

    Restoration of the knee joint: material from the specialists of the RC “Laboratory of Movement”


    Which doctor to contact

    How to treat a sprain

    Rehabilitation after a sprain



    Treatment and rehabilitation after a knee sprain in CMRT clinics

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    Jumper’s knee

    The most common traumatic injury seen in acyclic, speed-strength sports is patellar ligament tendonitis, or “jumper’s knee” as it is called. The specific inflammation associated with overload during landing after a jump requires an integrated approach to treatment and gradual physical rehabilitation.

    Injury of the medial collateral ligament

    One of the most common injuries of the ligamentous apparatus is damage to the medial collateral ligament of the knee joint. A strong connective tissue structure in most cases is not completely, but partially ruptured. However, a close connection with the internal meniscus invariably leads to a violation of its functionality with all the ensuing consequences. And only a timely appeal to a traumatologist increases the chances of a full recovery.

    Knee ligament rupture

    Knee ligament rupture is the second most common injury after meniscus injury. The pathological condition is accompanied by a violation of the integrity of the vessels, the ingress of blood into the joint. There are three stages – from mild to complete rupture, characterized by local pain, swelling of varying degrees and the onset of disability in severe cases.

    Ankle sprain

    The most common injury, typical for patients of various age categories, is an ankle sprain. Damage to the capsular-ligamentous apparatus with preservation or partial violation of its anatomical integrity is recognized as a serious medical and social problem. It can cause chronic instability and lead to degenerative changes in the joint. And only adequate orthopedic care and competent rehabilitation give a real chance for a full recovery.

    Recovery after rupture of ligaments

    One of the most insidious injuries that significantly limits a person’s motor activity is damage to the tendon-ligamentous apparatus. Violation of the integrity of the connective tissue fibers entails mechanical instability, persistent pain, partial or complete loss of function.

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    Damage to the medial collateral ligament – symptoms, causes, treatment

    A neurologist deals with the treatment of this disease.

    Make an appointment


    One of the most common injuries of the ligamentous apparatus is damage to the medial collateral ligament of the knee joint. A strong connective tissue structure in most cases is not completely, but partially ruptured. However, a close connection with the internal meniscus invariably leads to a violation of its functionality with all the ensuing consequences. And only a timely appeal to a traumatologist increases the chances of a full recovery.

    CMRT specialist tells

    Kuchenkov A.V.

    Orthopedist • Traumatologist • Surgeon • Phlebologist • Sports doctor • 25 years of experience

    Publication date: June 07, 2021

    Verification date: January 12, 2023

    All facts have been verified by a physician.

    Contents of the article

      Causes of damage

      Symptoms of damage

      Traumatic damage to the internal stabilizer of the knee is accompanied by a characteristic click and sharp pain. The joint in the projection of the ligament swells, movements are limited, hemarthrosis may develop within a few hours. With a partial isolated rupture, hemorrhage into the joint area is insignificant. Complete rupture of the tibial junction is accompanied by massive edema, diffuse hematoma, excessive mobility (instability) of the knee.

      Long-standing (chronic) injury is characterized by frequent clicks in the joint, pain of varying intensity, stiffness due to flexion contractures, functional blocks and sub-blocks.

      Degrees of damage

      There are 3 degrees of damage, established depending on the severity of the harm caused to health:

      • I – sprain with minimal rupture of the medial collateral ligament of the knee joint
      • II – partial tear of individual fibers
      • III – complete break; often combined with separation of the tibial junction from the place of attachment and injury to other articular structures.


      To clarify the nature of the injury and establish the final diagnosis,

      • valgus medial stress test (determination of ligament failure)
      • radiography in 2 projections (exclusion of intra-articular fracture)
      • CT
      • MRI
      • aspiration puncture (in the presence of hemarthrosis)
      • diagnostic arthroscopy

      Among the generally accepted diagnostic methods, magnetic resonance imaging is recognized as the most reliable, safe and informative. The high-tech imaging method allows not only to identify the exact localization of the stretch or rupture of the internal lateral ligament, but also provides an objective assessment of the state of all nearby soft tissue structures.

      Restoration of the knee joint: material from the specialists of the RC “Laboratory of Movement”


      Which doctor to contact

      How are knee stabilizer injuries treated?



      Treatment and rehabilitation after damage to the medial collateral ligament in CMRT

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