Knee Injuries

Overview of Common Knee Sports Injuries

In 2014, there were 10.4 million visits to a doctor’s office because of knee injuries. The knee is a complex joint with multiple components. This complexity makes it vulnerable to a variety of injuries. Knee injuries can be successfully treated using simple measures, such as physical therapy rehabilitation exercises and bracing.

Knee Components

The structures and components of the knee joint include:

  • Bones – Three bones meet to form the knee joint: femur (thighbone), tibia (shinbone), and patella (kneecap).Knee anatomy picture
  • Articular cartilage – The ends of the tibia and fibula, and back portion of the patella, are covered with a slippery articular cartilage. This allows the bones to glide smoothly across each other as you bend or extend the leg.
  • Meniscus – Two wedge-shaped pieces of cartilage that act as shock absorbers are the menisci (singular – meniscus). This tough, rubbery material stabilizes the joint.
  • Ligaments – Bones are connected to other bones via ligaments, and the knee contains four main ligament structures.
  • Tendons – These fibrous structures connect bones to muscles.

Knee Sprains and Strains

A sprain is a tear or stretch of a ligament, which holds bone to bone. A strain is injury of a tendon and/or muscle. You are at increased risk for knee injury if you have a history of strains and sprains, are overweight, or are in poor physical condition. Sprains and strains are categorized according to severity:

  • Mild – Tendon or ligament is stretched slightly, but there is no joint loosening.
  • Moderate – There are partial tears of the tendon or ligament, producing joint instability and some swelling.
  • Severe – Produces excruciating pain during movement, and the tear is complete.


The most common knee bone that is broken is the patella. Many patellar fractures are caused by high energy trauma, such as in a motor vehicle collision or a fall from a high structure. The patella is injured during sports by falling directly on it, or when there is a high impact collision with another player.


During sports play, a dislocation can occur when the bones of the knee go out of place. Dislocations are either partial or complete. The tibia and femur can be forced out of alignment, or the patella can slip out of position. A dislocation occurs as a result of sports-related contact.

Anterior Cruciate Ligament (ACL) Tears

The anterior cruciate ligament is often injured with sports play, such as football, basketball, and soccer. This ligament is torn when the athlete changes direction rapidly, or when he/she lands from a jump incorrectly. About 50% of ACL tears occur along with damage to another knee structure, such as meniscus, other ligaments, or articular cartilage.

Posterior Cruciate Ligament (PCL) Injuries

Tearing of the posterior cruciate ligament occurs from a direct blow to the front of the knee when the knee is in a bent position. PCL tears are usually partial tears and can heal without surgery.

Collateral Ligament Injuries

The collateral ligaments are torn or injured by a force that pushes the knee sideways, as with contact sports. Injury to the medial collateral ligament (MCL) often occurs from a direct blow outside of the knee, whereas the lateral collateral ligament (LCL) is injured from a blow to the inside of the knee.

Meniscal Tears

Tears to the meniscus occur when cutting, twisting, pivoting, or being tackled. These injuries also occur from arthritis or aging. A meniscal tear to a weakened meniscus can occur from an awkward twist when rising from a chair.

Tendon Tears

The patellar and quadriceps tendons can be torn or stretched easily during sports activities. These occur from falls, landing awkwardly from a jump, or from a direct force to the front aspect of the knee.

OSPI offers the top sports medicine specialists in Arizona serving Gilbert, Chandler, Mesa, Queen Creek and Maricopa AZ. All types of tendon and ligament injuries are treated with regenerative medicine procedures, bracing, physical therapy and operative procedures when necessary.

Most insurance is accepted, and the Board Certified orthopedic surgeons in Gilbert are experts at getting athletes back to activity quickly, call today!


Overview of Knee Collateral Ligament Injuries and Treatment

The lateral collateral ligament (LCL) and medial collateral ligament (MCL) are important for avoiding rotational instability of the knee joint, as well as preventing cartilage damage. A collateral ligament injury often requires reconstruction using the patient’s own tissue or donor tissue.

What is the purpose of the collateral ligaments?

The LCL is on the outer portion of the knee, and it connects the thigh bone (femur) to the leg bone (fibula). This

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ligament’s purpose is to avoid stress across the knee where it buckles outward. Along with other ligaments, the LCL forms a complex that provides external rotation stability. The MCL connects the thigh bone (femur) to the shin bone (tibia). It keeps the knee from buckling inward.

What are the symptoms of lateral collateral ligament injuries?

Injury to the LCL can lead to buckling of the knee. A direct blow on the inside of the knee can cause hyperextension stress on the LCL. This ligament often is torn along with the anterior cruciate ligament, which occurs from high-force sporting injuries. Symptoms include instability of the knee joint, mild knee pain, tenderness and swelling on the outer region of the knee, as well as weakness and/or numbness of the foot.

What are the symptoms of medial collateral ligament injuries?

With MCL injuries, you can have pain, tenderness, and swelling. Several hours after the initial injury, the pain may increase. You may also notice some bruising on the inner aspect of the knee.

How are collateral ligament injuries diagnosed?

The doctor diagnoses collateral ligament injuries based on symptoms, history of injury, physical examination, and magnetic resonance imaging (MRI) scans. X-rays can be normal, but MRI has a 90% accuracy rate for showing ligament tears. Ligament injuries are graded using a scale as follows:

  • Grade 1 injuries – Mild and usually gets better within 1-3 weeks. Only requires non-surgical treatment and use of crutches for a short while.
  • Grade 2 injuries – Moderate and usually gets better in 4-6 weeks. May require wearing a hinged knee brace and limited weight-bearing.
  • Grade 3 injuries – Severe and require wearing a hinged brace for several months. Weight-bearing is limited for 4-6 weeks. Often requires surgery.

What is the treatment for collateral ligament injuries?canstockphoto7107950

The LCL does not heal as well as the MCL. For minor tears, the doctor will recommend rest for a few weeks, use of ice to decrease swelling, elevation of the leg, and a compression bandage (ACE wrap). Physical therapy is used to restore strength and range of knee motion.

For high-grade tears, surgery is necessary. The doctor will reattach the ligament using large stitches or a suture anchor. If the ligament is torn into two pieces, the pieces can be sewed together. When a graft is used, the new structure is attached to replace the torn ligament.

How common are collateral ligament injuries?

According to statistics, the incidence of acute knee injury in the U.S. is 300 cases per 100,000 persons per year. Collateral ligament injuries make up 25% of all acute knee emergency room visits. These injuries are more common in adults aged 20 to 34 years. The NCAA reports 2 collateral injuries per 1,000 player exposures in a year.

OSPI has been the top sports medicine orthopedic doctors in the East Valley for years, with sports medicine physicians providing comprehensive operative and nonoperative care for all types of knee injuries. Call us today!


National Collegiate Athletic Association. NCAA Injury Surveillance System. 1999-2000.

Yawn BP, Amadio P, Harmsen WS, et al. Isolated acute knee injuries in the general population. J Trauma. 2000 Apr. 48(4):716-23.