Common Knee Injuries with Dr. Jason Tarno

The knee is commonly injured. What are the most common injuries to the knee in sports?

Twisting injuries are by far the most common. This can happen with the quick change-of-direction inherent in any sport, or after landing awkwardly after a jump.

What are the bones at the knee?

The bones that make up the knee joint consist of the femur (thigh bone), the tibia (shin bone), patella (knee cap), and fibula (A smaller long bone just lateral to the tibia. This bone is non-weight bearing).

What are the ligaments at the knee?

There are four major ligaments in the knee. On the outside (lateral) and inside (medial) of the knee are the collateral ligaments. They help keep the knee straight. Any weakness or tearing of these ligaments can cause the knee to bow or become knock-kneed depending on which ligament is injured. Within the knee joint itself, there are two ligaments that attach from the femur to the tibia and give stability to the knee with stopping/ starting. These ligaments are termed the cruciate ligaments (Cruciate is Latin for cross). The two ligaments cross one another, one in front, the anterior cruciate ligament (ACL), and the one behind, the posterior cruciate ligament (PCL). The ACL is very critical in sports such as basketball, soccer, football, etc… where there are rapid changes in direction. Without this ligament, the tibia can translate forward on the femur with change of direction. This leads to extreme instability with sporting events. Also, when the knee gives out, the joint surfaces of the femur and tibia can be damaged, leading to arthritis.

What kind of shock absorber is in the knee?

The knee possesses a rubbery type of shock absorber between the femur and tibia, which we call meniscus. The meniscus is made of cartilage. There are two menisci in the knee – a medial and lateral. Occasionally the menisci can be damaged, leading to pain, swelling, stiffness, and sometimes a feeling of “locking” within the knee joint.

What is the difference between an x-ray and an MRI?

X-ray imaging uses very small amounts of radiation, projected from a tube through your body and onto a film plate. Structures in your body block a portion of the rays and result in different shades of exposure on the film plate. Denser structures, such as bone, will block more rays and show up as a lighter image on the exposed film you see. MRI stands for magnetic resonance imaging. This is an imaging technique that utilizes magnetic fields in an interaction with atoms from a person’s body. A computer analyzes the information, and an image is produced.

Is there any radiation exposure with an MRI scan?

No. There is no radiation exposure. The magnetic field is safe for any person unless certain metal devices have been placed, such as a cardiac pacemaker.

What is better: an x-ray or an MRI?

It really depends on what type of information the physician is trying to obtain. X-rays are very helpful in looking at bony abnormalities. They give a better “lay of the land” type of view of the body part in question. Ligaments, tendons, and muscles do not show up on plain film x-rays, but physicians can often make assessments about them based on what the osseous (bony) structures look like. The MRI gives very good information regarding integrity of ligaments, tendons, muscles, and cartilage.

We often hear about an athlete injuring their knee, having an MRI, and then going for arthroscopic surgery. How is arthroscopic surgery different from a “regular” surgery?

Arthroscopic surgery is generally an outpatient procedure that usually does not take as long as open surgery. Two to three small incisions are made at the knee (each about 1 cm) in length. Instruments are then placed within the joint. One of the instruments is a video camera, and that is attached to a monitor that the surgeon uses to visualize the joint. The surgeon can then remove any debris or tears within the knee. The benefit of this type of surgery is that it is shorter, has less anesthesia, and usually shorter rehab periods.

Is physical therapy necessary after a knee injury?

Depending on the injury, the patient and the physician make that decision in concert. Usually after a surgical procedure, some type of therapy is prescribed. During surgery the knee is subjected to stresses that it is not normally exposed to. These stresses, combined with the need to strengthen the athlete’s knee from the initial injury, require a specific amount of therapy and rehabilitation tailored to the athlete’s individual need.

- Jason M. Tarno, D.O., is Board Certified and Fellowship trained in Sports Medicine. Dr. Tarno is an associate of Crovetti Orthopaedics and Sports Medicine.

For further information call: 990-2290.

Or visit us at: www.CrovettiOrtho.com