Cruciate and Collateral ligaments
Anterior Cruciate Ligament (ACL)
How it happens: A twisting injury involving the knee often causes the ACL to reach a maximum level of loading force and the ACL ruptures. Another way the ACL is torn is with an impact or a tackle to the outside of the knee while the leg is straight.
Symptoms: patients hear a “pop” in their knee, knee giving way (instability), swelling hours after the injury, stiffness, pain, bruising.
Posterior Cruciate Ligament (PCL)
How it happens: Usually tears when the front of the tibia is impacted with a large force like during a motor vehicle accident and the patient’s lower leg slams into the dashboard.
Symptoms: knee giving way (instability), swelling hours after the injury, stiffness, pain, bruising.
Medial Collateral Ligament (MCL)
How it happens: With an impact or a tackle to the outside of the knee while the leg is straight. While the outside of the knee takes the brunt of the force, the inside of the knee joint gets very wide and the MCL fails. This is common in football, baseball and soccer. The MCL is also a ligament that can tear along with the injury that caused the ACL to tear.
Symptoms: tenderness on the inside of the knee, swelling
Lateral Collateral Ligament (LCL)
How it happens: With an impact or a tackle to the inside of the knee while the leg is straight. While the inside of the knee takes the brunt of the force, the outside of the knee joint gets very wide and the LCL fails. This is common in football and soccer during a tackle.
Symptoms: tenderness to the outside of the knee, swelling, stiffness.
Rest, Ice, Compression, and Elevation The RICE method may help reduce discomfort and swelling:
- Rest—Avoid putting any pressure on your knee by not walking on that leg
- Ice—Apply ice or a cold pack to the knee to reduce pain and swelling
- Compression—Wrap your knee in an elastic bandage to limit swelling and provide support
- Elevation—Keep the injured knee raised above the level of your heart. This will help drain fluid and reduce swelling
Exercises may be advised to restore flexibility, range of motion, and strength. A referral to a physical therapist may be needed.
Surgery may be needed if a ligament is torn completely.
To reduce the risk of knee sprains:
- Warm up and stretch before exercise. Cool down and stretch after exercise
- Take a break from sports and exercise when you feel tired
- Do exercises that strengthen the leg muscles
- Learn the proper technique for sports and exercise. This will decrease stress on all muscles, ligaments, and tendons, including those around the knee. Also, wear the proper equipment
- Ask your doctor if you should use a brace
Patella (knee cap) dislocation
A patella dislocation occurs when the kneecap slides out of place. The patella is the bone more commonly known as the kneecap. It fits securely in a V-shaped groove in front of the knee so that the patella can move up and down when the leg is bent or straightened.
Patella dislocation is very common and occurs when the knee is bent. The patella is out of the groove when the knee is bent and can be vulnerable to dislocation with trauma. Straightening the knee will bring the patella back in place in the groove of the knee when a dislocation occurs.
Treatment includes nonsurgical manipulation of the patella, immobilization, medications, and physical therapy. In some cases, surgery may be required to repair damage caused by the dislocation.
Trauma or abnormal movement at the knee causes patella dislocation. Examples include:
- A direct blow to the knee or from injury, such as a fall
- Tension that applies force from side-to-side on the patella
- Sudden twisting motions
Factors that may increase your chance of patella dislocation include:
- Shallow V-shaped groove on front of your knee
- Knock knees—knees angled inward and touching when the legs are straight
- Flat feet —fallen arches in the feet
- Excess pronation of the feet—inward roll of the feet when walking or running
Other factors that can create instability in the patella include:
- Weak thigh muscles
- A patella that sits too high on the thigh bone
- Weakened and stretched ligaments from a previous patella dislocations
Patella dislocation may cause:
- Extreme pain and swelling at the knee
- Buckling under your own weight
- Abnormal appearance of the knee
Your doctor will ask about your symptoms and medical history. A physical exam will be done. This will include a thorough exam of your patella to check for tenderness and swelling. If possible, your doctor will have you walk. Your doctor may be able to make the diagnosis based on your symptoms.
Images may be taken of your knee. This can be done with:
- CT scan
- Computed tomography angiography (CTA) scan
- MRI scan
If the patella did not return to the V-shaped groove on its own, the doctor will manipulate it back into place.
The knee will be immobilized in a brace for stability and support. A brace may be needed for up to 4 weeks. Activities will be limited until the knee is stable again.
Medications may be given to help reduce swelling and reduce pain.
Physical therapy may be recommended to:
- Stretch and condition the quadriceps and hamstring muscles
- Maintain muscle strength, flexibility, and endurance
- Improve balance and range of motion
Improving leg strength may help prevent future dislocations.
Surgery may be needed for recurrent patella dislocation or dislocations with severe injuries to soft tissue. It may also be needed for those who don’t recover with standard medical therapy. Surgical procedures include:
- Arthroscopic repair of damaged cartilage, or to realign ligaments or tendons that stabilize the patella
- Reconstruction of medial patellofemoral ligament to help with stability and prevent recurrent dislocations
To help reduce your chance of patella dislocation, keep your quadriceps and hamstring muscles strong with strengthening and stretching exercises.
Patella (knee cap) Fracture
A patella fracture occurs when there is a break in the patella, better known as the kneecap. The patella is a large, movable bone at the front of the knee.
Some common causes of this injury include:
- Sharp blow to the knee
- Excessive stress on the knee
Factors that may increase your risk of a patella fracture include:
- Increased age
- Decreased muscle mass
- Decreased bone mass— osteoporosis
- Participation in contact sports such as football and soccer
- Obesity, which places strain on muscles, bones, tendons, and ligaments
- Violence, such as car or car-pedestrian accidents
Patella fracture may cause:
- Sudden, excruciating pain in the kneecap
- Swelling, bruising, and tenderness
- Inability to extend the knee
- Difficulty walking
You will be asked about your symptoms and medical history. A physical exam will be done. The doctor will look closely at the knee to see if there are signs of fracture. A straight leg test may be done.
Images can evaluate your knee and surrounding structures. These may include:
- CT scan
- MRI scan
Treatment options include the following:
After the tests, the doctor will determined whether surgery is needed. If the patella is not badly injured, the doctor will place the knee in a cast. This cast may need to be worn for 6 weeks. After that, a knee brace and physical therapy will be needed. A cane or crutches may be needed.
Medication may be advised to reduce swelling and pain.
If the patella is in pieces, then surgery will be needed. There are 2 kinds of surgery that are commonly used to treat this injury:
- Open reduction-internal fixation surgery —The doctor uses pins and screws to put the broken pieces back together
- Patellectomy—Rarely, the doctor removes part of the kneecap or the entire kneecap
After surgery, physical therapy will be needed. This can involve range-of-motion exercises and stretching. In some cases, another surgery will be needed to remove the pins and screws.
Depending on the injury, recovery can take weeks to several months.
To help reduce your chance of a patella fracture:
- Do not put yourself at risk for trauma to the bone
- Do weight-bearing exercises to build strong bones
- Build strong muscles to support the knee, prevent falls, and to stay active and agile
- Wear proper padding and safety equipment when participating in sports or activities
Tendons are thick bands of connective tissue that connect muscle to bone. Similar to ligaments, they are made of collagen and can withstand increased tension. Tendons are the reason a muscle can move the bones in our body when muscles contract.
The tendons involved in the knee include the quadriceps tendon, the patella tendon, hamstring tendons, and the iliotibial band.
The quadriceps tendon connect the quadriceps muscle to the patella (kneecap) and provides the power for straightening the leg. The quadriceps muscle is a group of four muscles; from outside to inside they are vastus lateralis, vastus intermedius, vastus medialis with rectus femoris lying over top of vastus intermedius.
A common injury in jumpers is a quadriceps tendon rupture. On an X-ray view of the side of the knee the patella would be lower than normal as it migrates down the front of the knee because of losing its attachment with the quadriceps muscle. Often times, this needs surgical repair.
The patellar tendon is not actually a real tendon as it does not connect muscle to bone. The patellar tendon connect the patella to the front of the tibia (shinbone). It’s named a tendon because in a sense it is the continuation of the quadriceps tendon after the patella. This tendon is helpful in straightening the knee as well.
The patellar tendon can rupture in jumpers as well with a hard landing. On an X-ray view of the side of the knee the patella would be higher than normal as it migrates up the front of the knee because of losing its attachment with the tibia (shinbone). This tendon can also rupture if the front of the knee is hit hard or a person falls and takes the impact on this tendon. This often needs surgical repair.
A common problem with this tendon is known as patellar tendonitis or tendinosis and is often seen in runners and jumpers. The tendon becomes very irritated and small tears occur in the tendon. As the tendon tries to heal itself, scar tissue may build up which can become painful. This is treated with rehabilitation.
The hamstrings tendon starts at the bottom of the pelvis and runs along the back of the thigh to connect to the knee at the shinbone. Hamstrings is a group of four muscles; Gracilis, Semimembranosus, Semitendinosus and Biceps Femoris. Respectively, the first three connect to the inside part of the knee and the fourth connects to the outside. Together, they are responsible for bending the knee and swinging your leg behind you while straight. This group of muscles help propel us forward or backward when sprinting. Many factors can contribute to an injury to the hamstrings including improper stretching where the muscle is too tight, the muscle getting too tired or muscle imbalance due to poor conditioning and strengthening of this muscle group. These factors can lead to hamstring strains or a partial rupture which are more common. Although a complete rupture of this muscle is not common, if it were to happen it would more than likely occur at the bottom of the pelvis and the muscle is left as a bundle along the back of the thigh. This rarely needs surgery and can be rehabilitated back to no pain.
The iliotibial band is the longest tendon in the body. It arises from the ends of the tensor fascia latae muscle and gluteus maximus muscle to connect from the outside of the hip down to the outside of the knee at the shinbone. This thick and wide tendon helps us raise our leg to the side (abduct) and rotate our leg outward at the hip joint. A common problem with the IT band causing pain at the knee is called IT band syndrome. This is seen in runners where the attachment segment of the tendon at the knee joint becomes very irritated as it rubs against the side of the shinbone during repeated bending and straightening of the knee. If the IT band is very tight and not well conditioned this area of the knee can become very irritated. Another common problem is called snapping hip. With this, the tendon has a “popping” or “snapping” sensation at the hip where an individual may think their hip is popping out of joint when in fact, the IT band is making all the noise. When you are standing up the IT band lays behind a bony prominence on the femur called the greater trochanter of your hip and when you bend your knee the band moves to the front of the greater trochanter. This popping is a result of the IT band gliding across this bony structure of the femur while walking or running or even getting up from a chair.
Lastly, the gastrocnemius muscle (calf muscle) attaches to the back of the knee and arises from the Achilles tendon at the ankle. The gastroc has two segments; the inside (medial) and the outside (lateral) segment. Each of them attach to the end of the thigh bone to help in bending the knee, walking and raising your heel off the ground when going up on your toes. A common injury is a medial gastroc tear with a sudden pop in the upper third of the calf muscle. There will be bleeding, bruising, and pain with walking. This is an injury that needs rest and rehabilitation, but will heal over time.
Meniscus and Cartilage of the knee
These two structures serve as shock absorption for the knee. The cartilage is the most important surface in the knee for absorbing shock. It serves as a gliding surface for when the knee bends, straightens and slightly rotates. It is made of a thick, smooth tissue that acts as a protective covering over the ends of the longs bones at the joint space.
Injuries to the cartilage occur either with trauma or over long periods of time where these surfaces slowly deteriorate due to wear and tear. When the process is slow and gradual the damage is often worse. Eventually the cartilage is worn off and the surface of the two ends of bone are no longer gliding on a smooth surface with movement, but instead grinding together. This is very painful to the person when walking. It can also cause swelling and stiffness in the knee joint.
The meniscus in the knee is like a gasket and also serves as a shock absorber. The knee is the only place in the body that you find meniscus. And it is only found on the surface of the tibia (shinbone) that makes contact with the femur (thigh bone). The curvature of the meniscus as it extends from the tibia match the curvature of the end the femur (thigh bone). The fibers of the meniscus is made of a complex interlocking matrix to withstand twisting forces as the two ends of bone glide across the surface during movement. They help distribute the forces through the knee. The meniscus on the outside (lateral) part of the knee is wider, more curved and covers more surface area than the meniscus on the inside (medial) part of the knee.