Types of Knee Sprains & Tears

An injury to the ligament [overstretching or tearing of fibers] is called a sprain. Ligaments are tough fibrous tissues that link two bones in a joint and provide support and limit excessive movements.

A tear occurs when the body’s soft tissues, such as a muscle, ligament, or cartilage, are ripped apart in two or separated from its bone attachment.

Structures of the Knee

The knee is the largest joint in the body and comprises ligaments, bones, cartilage, tendons, and bursa that support and stabilize it during movements.

Ligaments of the knee. Anterior and Posterior cruciate ligaments, Patellar and Quadriceps, tendons, Medial and Lateral collateral ligaments. joint anatomy. Vector illustration for biological, medical, science and educational use

The ligaments of the knee are categorized into two: the cruciate ligaments consisting of the ACL (anterior cruciate ligament) and the PCL (posterior cruciate ligament); and the collateral ligaments consisting of the MCL (medial collateral ligament) and the LCL (lateral collateral ligament).

The ACL and the PCL cross each other to form the “X” structure in the middle of the knee joint. They are responsible for stabilizing the knee and preventing the lower leg’s bone from slipping forward or backward excessively relative to the thigh bone.

The MCL and the LCL are ligaments at the knee’s inner side and outer side, respectively. The MCL is attached from the inner side of the thigh bone (femur) to the bigger bone of the lower leg (tibia) and prevents the lower leg from moving excessively inward.

Meanwhile, the LCL is attached from the outer side of the tibia to the smaller bone of the lower leg (fibula) and prevents the lower leg from moving excessively outward. Together, they limit excessive side-to-side motions of the knee.

Another important structure in the knee joint is the cartilage.

  • The articular cartilage is strong, slippery material that covers the surface of bones and enables bones to move over one another smoothly.
  • The thick pad of cartilage between the femur and tibia in the knee joint is called menisci (plural of meniscus). The medial meniscus and lateral meniscus are crescent-shaped cartilages that act as a cushion protecting the knee from stress brought by walking, running, climbing, and jumping.

Knee Sprain and Knee Tear: Definition and Classification

A knee sprain occurs when any of the cruciate or collateral ligaments are stretched or torn due to sudden or excessive force. It can be classified as

  • Mild (grade I) or stretched
  • Moderate (grade II) or partially torn
  • Severe (grade III) or completely torn.

Knee tear occurs when any of the ligaments or menisci are ripped apart or separated from the bone where it attaches. The ligament or meniscus can be partially damaged or fully damaged, or detached from the bone. Knee tears are classified into three types:

Cruciate Ligament Tears

The ACL is the most commonly torn ligament and occurs mostly as a result of athletic activities. The PCL is the strongest ligament among the four ligaments of the knee; thus, it is less commonly injured.

Collateral Ligament Tears

MCL and LCL tears are fairly uncommon to occur independently and are usually accompanied by a tear in either of the cruciate ligaments. Similar to the ACL, collateral ligament tears are frequently obtained through contact sports.

Meniscal Tears

The menisci of the knee face each other to form a ring that encircles the ACL and the PCL located in the middle of the knee joint. Meniscal tears are commonly known as “torn cartilage,” and they also occur due to contact sports injury.

Causes of Knee Sprain and Knee Tear

A knee sprain can be due to a sudden force or movement that causes stress to the knee’s ligaments.

ACL sprain or tear can happen due to sudden stopping, twisting, pivoting, or changing direction or when there is direct and forceful impact at the back of the lower leg.

The most common cause of PCL sprain or tear directly impacts the front of the lower leg, such as in a “dashboard injury” typical in automobile accidents. It can also occur due to landing hard when the knee is bent during a sports activity.

A blow on the outer side of the knee that moves the lower leg excessively inwards results in an MCL sprain or tear. An impact on the inner side of the knee that moves the lower leg excessively outwards results in an LCL sprain or tear. Injuries to both collateral ligaments can occur due to sports and activities that require frequent twisting or pivoting.

Meniscal tears can occur when there is excessive pressure or extreme rotation on the knee. Activities that may cause a tear in any of the menisci include deep squatting, sudden twisting, and heavy lifting.

A worn meniscus due to age or micro-tears that occurred over time may result in degenerative tears. These are common in elderly individuals, which puts them at risk for damaging the meniscus even with simple activities such as awkward stepping during walking or getting up from a chair.

Damage to a single knee structure is fairly uncommon; most are a combination of different structures as they work together as a unit.

The “unhappy triad” is a severe injury to the knee joint that involves damage to the ACL, MCL, and medial meniscus. When the foot is planted on the ground, the knee is slightly bent, and there is forceful twisting or rotating on the knee.


The RICE protocol is frequently recommended by doctors for Grade I or II knee sprain. It stands for:

  • Rest the affected leg and avoid weight-bearing
  • Ice the injured part for 20 minutes to lessen the pain and swelling.
  • Compress using an elastic bandage or sleeve.
  • Elevate above the level of the heart.

Although the RICE protocol has been used for decades, several studies have debunked it and claimed that it could even hinder tissue healing.

Instead of the RICE protocol, the PEACE and LOVE are being suggested by many orthopedics and physical therapists. Immediately after a soft tissue injury, it is recommended to perform PEACE which stands for:

  • Protect the area by restricting movement for 1 to 3 days.
  • Elevate higher than the heart.
  • Avoid anti-inflammatory modalities such as medication and use of ice which can potentially delay tissue healing.
  • Compress using bandage or tape.
  • Educate the patient in his/her condition, recovery time, and the importance of active participation.

After a few days of healing, LOVE is suggested, which stands for:

  • Load the injured part using active, controlled exercises to promote repair and healing.
  • Optimism should be encouraged to lessen the effect of barriers to recovery such as fear and depression.
  • Vascularization through early mobilization and aerobic exercise to improve function and facilitate return to activity.
  • Exercise to restore mobility, strength, and function while avoiding pain and using it to guide exercise progression.

Knee injuries are mostly managed conservatively. However, severe damage to the knee structures may require surgery depending on which structure is affected, the extent of the injury, and the individual’s lifestyle.


Physical therapy intervention is usually enough to manage knee sprain or tear. Whether the doctor recommends conservative treatment or surgery, both will require physical therapy management.

It aims to strengthen the muscles of the knee, restore normal range of motion, improve balance and coordination, and facilitate proper body mechanics and joint conservation techniques.

Physical therapy aims to depend on the type of knee injury, the goal of the patient and referring physician, and the lifestyle, occupation, and daily activities of the patient.

Exercises are usually done in a slow, progressive manner. It includes direct strengthening of muscles, flexibility, balance, and aerobic exercises for general body conditioning.

Questions to Ask Your Doctor

Sustaining an injury and recovering from it is a long and difficult process. Having the proper knowledge could save one from obtaining another injury or causing re-injury to the already vulnerable knee.

These are some of the questions that can be asked during a visit to the doctor:

  • What are the activities that I can perform while recovering from the injury?
  • How do I prevent re-injury on the same leg or the same injury on the unaffected leg?
  • What are the things that I should look for that indicate that my injury is getting worse?
  • What should I expect from physical therapy?
  • How can I say that I am doing the exercises correctly and not harming the injured leg?

Leave a Comment