The anterior cruciate ligament (ACL) is a ligament in the knee that prevents the tibia from sliding forward relative to the femur. It is an important stabilizer in the knee. The ACL can be injured during a pivot, when the foot is planted and the knee twists, or when landing awkwardly from a jump. Female athletes are 3 times more likely to sustain an ACL injury compared to males.

Symptoms of an ACL tear may include:

• Feeling or hearing a popping noise in the knee
• Pain on the outside and back of the knee
• Constant swelling within the first few hours of the injury
• Limited knee movement because of pain or swelling or both
• The knee feeling unstable, buckling, or giving out

It is worth noting that over 50% of patients who tear their ACL also suffer from an injury to the meniscus.

Causes of the injury may include:

• Taking a hit very hard on the side of the knee, forcing it to twist unnaturally
• Overextend the knee joint
• A quick change of direction while running, landing from a jump, or turning

The posterior cruciate ligament (PCL) is a ligament located in the back of the knee that connects the femur to the tibia. The PCL keeps the tibia from moving backwards on the femur.

Symptoms of a PCL injury typically include pain and swelling at the time of injury which may also be felt in the calf region. The patient will feel instability in the joint and the feeling of the knee giving out. Pain is reproduced by attempting to bend the knee the wrong way, which strains the PCL. There may be visual deformity

An injury to the PCL requires quite an impact. A common cause of the injury is a bent knee during a motor vehicle accident or an athlete falling on a knee that is bent. If the ligament is not torn but only sprained surgery is rarely needed, but when the PCL is torn it is very common for other ligaments to be torn as well, making surgery a challenge.

The Medial Collateral Ligament (MCL) is the ligament located on the inner side of the knee responsible for connecting the shin bone to the thigh bone. A strain or sprain most often occurs if excessive directional force is applied to the ligament.  

MCL injuries are a common occurrence in sports and more specifically, contact sports.  Direct force is often applied by the opponent to the outside of the leg directly above the knee.  This force causes the ligaments to be stretched past their intended capacity which causes the injury.

Another common incidence for this injury is shoes or cleats getting stuck in the grass or turf.  As the player attempts to change direction the foot remains planted and sudden excessive force is applied to the ligament causing damage.

Symptoms may include:

• Soreness in the knee
• Sensitivity to touch or pressure
• Pain when bending or bearing weight on the knee
• Inability to bear any weight on the knee
• Swelling within 24 hours of injury
• Fluid in the knee
• Damage to other knee structures

The two menisci of the knee are labeled the medial meniscus and the lateral meniscus. They are wedges of cartilage that fill the gap between the tibia and femur. The menisci provide stability in the knee by creating a cup for the end of the femur to sit in.

The meniscus can be torn during activities that cause direct contact to or pressure on the knee. A sudden pivot, deep squatting, or heavy lifting can lead to an injury to the meniscus. Sports that require sudden turns and stops, put someone at higher risk for an injury to the meniscus as well.

A “popping” noise will often accompany a meniscus tear. In most cases the patient will be able to walk on the injured knee. In fact, many athletes keep playing with a tear. Over 2 to 3 days, the knee will gradually become more stiff and swollen.

The most common symptoms of meniscal tear are:

• Pain
• Stiffness and swelling
• The knee catching or locking
• The feeling of the knee “giving way”
• Loss of full range of motion in the knee

Arthritis of the knee is a common condition in the aging population.  Traditionally, arthritis of the knee will take three forms: Osteoarthritis, Rheumatoid Arthritis and Post-traumatic Arthritis

• Osteoarthritis is usually a form of arthritis that progresses slowly.  As we age, the joint cartilage of the knee tends to degenerate as a result of long term wear and tear and degeneration.  This degeneration can cause bones in the knee to rub together resulting in pain and bone spurs.
• Rheumatoid Arthritis (RA) is an inflammatory arthritis that slowly destroys the cartilage of the knee.  RA can occur at any age and the likelihood of RA is based on a combination of genetic and environmental factors.  Those with RA most often experience the condition in both knees.
• Post-traumatic Arthritis may occur over a longer period of time much like Osteoarthritis. In most instances, the degeneration occurs as a result of a previous injury to the cartilage, ligaments or unhealed fracture.  Symptoms may not arise until years after the initial injury occurs.

Signs and Symptoms of Knee Arthritis can vary depending on type:

• Swelling of the knee
• Stiffness of the knee
• Sensitivity to touch
• “Locking” or “buckling” of the joints
• Increased pain when walking, climbing or after periods of activity

A patella injury is caused by damage to the cartilage under the kneecap. This cartilage acts as a shock absorber and distributes weight and force throughout the knee. Degeneration of this cartilage can be a result of repetitive concussive forces to the knee joint or the patella. When this cartilage becomes worn or damaged it can cause the kneecap to rub directly against the knee joint resulting in a dull pain. The pain is most often felt during physical activity or prolonged periods of sitting.

This can be a common athletic injury in sports that require excessive running, use of the knee for generating force or change in direction (soccer, tennis, basketball, cycling, gymnasts, equestrians, skate/snowboarders).

Signs and symptoms of a patella injury can include:

• Dull pain in the knee
• Aching in the knee
• Limited range of motion in the knee
• Sensitivity to touch
• Difficulty climbing stairs

A patella injury would result in one of these conditions:

• Chondromalacia Patellae (Runner’s knee) – The result of irritation to the cartilage under the kneecap. This is the most common condition associated with the patella.
• Prepatellar Bursitis (Housemaid’s Knee) – Swelling and inflammation over the front of knee. Caused by kneeling for an extended period.
• Patellar Subluxation- The result of an unstable kneecap. The kneecap does not track evenly within its groove. MPFL Reconstruction is required.
• Kneecap Dislocation- This occurs when the kneecap comes completely out of its groove. This condition is also called a patella dislocation. MPFL Reconstruction is required to fit the kneecap back into the groove.
• Patellar Tendon Tear- This is a very serious injury that occurs when the tendon connecting the kneecap to the shin is ruptured. There is a 6 month recovery period and 8-10 months for a return to physical activity.

Patella dislocations occur fairly regularly, especially with the younger generation. This injury can occur either in contact or non-contact situations. An athlete can dislocate their patella when the foot is planted and a rapid change of direction or twisting occurs. Usually a pre-existing ligamentous laxity (loose ligaments) is required to allow a dislocation to occur without any contact. Direct blows to a knee will cause dislocations as well. The force of these is obviously much greater and usually causes more severe damage, especially to the surrounding ligaments.

Symptoms may include:

• Rapid swelling.
• Excruciating pain until relocation occurs.
• Continued pain along medial ligaments.
• Discoloration/deformity at site of ligament injury.

This injury can be treated non-operatively, with immobilization for 7-14 days and a recovery period of 3 to 6 weeks total. Unfortunately, if the injury occurs where the patient’s ligaments are loosened, there will still be a risk for dislocation if the knee is not operated on. Surgical procedures on the patella are usually done in the outpatient setting. Procedures limited to altering soft-tissue tension begin rehabilitation within a week and return to activity can be expected as early as six weeks. Procedures that will repair injuries to the bone itself will require a period of relative immobilization and need 10 to 12 weeks before a return to athletic activity is permitted.

Chondromalacia patella is a softening of the cartilage underneath the kneecap and is known as one of the main causes of knee pain. Degeneration of cartilage is often the result of poor alignment of the patella it slides over the lower end of the thighbone (femur). This process is also sometimes referred to as patellofemoral syndrome.

The primary goal for treatment and rehabilitation of chondromalacia patella is to create a straighter pathway for the patella to follow during quadriceps contraction. This generally means resting and icing the knee often, and avoiding movements that are known to irritate the kneecap.

Non-surgical treatment is recommended and would always be the first option, but in some cases arthroscopic surgery must be performed to relieve the pain. This procedure would smooth off the arthritic wear and tear and release the fibrous band of tissue attached to the outside of the patella. This would provide a permanent stabilization similar to a knee brace.

Patella Maltracking is an imbalance in the gliding of the kneecap that aggravates the cartilage in back of the knee. Rather than moving vertically as the knee bends, a maltracking patella is pulled to the outward side as it moves upward in the groove. This may result in pain on the outward and front sides of the knee, clicking sounds, swelling, and pain from both activity and long bouts of sitting.

Common causes of patella maltracking include problems with foot alignment and muscle strength. Muscle imbalances in the quadriceps or gluteus maximus may aggravate this condition as well.

Non-surgical treatment is recommended and would always be the first option, but in some cases arthroscopic surgery must be performed to relieve the pain. This procedure would smooth off the arthritic wear and tear and release the fibrous band of tissue attached to the outside of the patella. This would provide a permanent stabilization similar to a knee brace.

A pulled hamstring is a common term that refers to a strain of one or more of the hamstring muscles, which are located in the back of the thigh. Depending on the severity of the strain injury, the muscle can actually tear and many people can hear an audible “popping” noise when the muscle is damaged.

These injuries are labeled as acute or chronic. Causes that may lead to an acute injury are:

• A poor job warming up/stretching
• Poor lower back flexibility
• Abnormal biomechanics

Chronic hamstring injuries are usually the result of an improperly rehabilitated acute injury, but may occur as the result of small amounts of trauma over a long period (common for distance runners). Poor hamstring flexibility increases the likelihood of a small tear in the muscle, which in turn causes the muscle to shorten and become tighter. Prompt and appropriate initial treatment are very important so that a viscous circle does not become established.  Tears of the hamstring from their origin in the buttock may require surgical repair.

Osteochondritis dissecans involves a loss of blood supply or even death to part of the cartilage within the knee joint. The cause of this may be related to repetitive trauma (undiagnosed injury(s) that damage the bone and cartilage). It can also come about due to genetic family history.

This condition most often affects teens between the ages of 11-18, especially teens who are active in high-impact sports, such as football, basketball, soccer and weight-lifting. As noted above, it is thought to be related to repeated impact to, or use of the knee, which over time slows or stops the blood flow to the cartilage. It is very common for the patient not to be aware that any cartilage injury has taken place until pain or loss of mobility occurs.

Some common symptoms of Osteochondritis Dissecans are:

• Pain, especially when fully bending or straightening the knee
• Knee catching and locking when bending
• Swelling and tenderness
• Difficulty moving
• Loss of full range of motion