Lateral Patellar Instability and the Medial Patellofemoral Ligament (MPFL)

Lateral patellar instability occurs when the kneecap dislocates out of place. The kneecap or patella is a small bone in the front of the knee. It glides along the femoral groove (a groove in the femur bone) as the knee bends and straightens. If the patella comes out of the groove completely, it is referred to as patellar dislocation. If the patella comes out of the groove partially, it is referred to as patellar subluxation.

Symptoms of dislocations of the kneecap are as follows:

-          Pain at the knee joint
-          Swelling
-          Obvious displacement of the kneecap (kneecap can often briefly dislocate and return, but pain and swelling will still be present)

When the kneecap dislocates, it often tears the medial patellofemoral ligament on the inside of the knee. The MPFL is a thin band of tissue that attaches the kneecap to the inner part of the knee. The medial patellofemoral ligament or MPFL is important for stability in the knee.

There are surgical and non-surgical treatments for patellar instability. Rest, ice and bracing have been known to heal the injury and prevent recurrent dislocations. However, surgical intervention is sometimes needed to correct recurrent dislocations.

If the MPFL is torn, the patient can potentially benefit from a surgical procedure known as MPFL reconstruction. Reconstruction of the MPFL is a surgical procedure that restores patellofemoral stability. The most successful and widely accepted approach to this procedure is to use an approach that restores the MPFL to its anatomically correct position. This procedure, along with other options, such as tibial tubercle osteotomy, and/or a trochleoplasty can be used to correct the problem. The exact treatment protocol varies by individual.

 

ACL SURGICAL NEWS: ALLOGRAFT VS. AUTOGRAFT

When the ACL is torn, is can rarely be repaired. Surgery is often required to reconstruct the ACL. If reconstruction is not performed, the knee is at increased risk of cartilage damage, meniscal tear and osteoarthritis. Especially in younger patients, surgical repair is recommended following an ACL tear.

Surgery is performed arthroscopically and the ACL is either repaired or replaced. If the torn ligament cannot be repaired, the ACL is replaced with a tissue graft. The surgeon and patient have the option to use autograft tissue or allograft tissue.

Autograft tissue is a tendon from another location on the patient’s body. Most commonly a surgeon would use a hamstring tendon or patellar bone tendon bone. With the patellar bone tendon bone, the middle third of the tendon is removed and used as the new ACL.

Allograft tissue is a cadaver tendon that is taken from another person. In this case, the surgeon would use the achilles tendon, patellar bone tendon bone or a hamstring tendon.

Autograft is recommended for patients 30 years old or younger. The failure rate of allograft tendons is much higher in those under the age of 30 and the risk of infection is very low. The downside of using the patient’s tissue is that the operation is more involved and painful. The surgeon must surgically remove the autograft tendon and then also repair the ACL. The patient is undergoing two procedures as opposed to one. 

Allograft tendons are preferred in patients over the age of 30. The advantage of allograft is that it involves less surgical time and is less painful. The disadvantage of allograft is increased risk of infection and rejection. It is important to mention that the advances in allograft testing and sterilization have improved significantly in recent years. Risk of infection and disease is extremely low. Another advantage with allograft is that there are now numerous options to choose from, which allows the surgeon some flexibility in deciding which option is best for each individual patient.

In summary, if you are having surgery on your ACL, it is best to talk to your orthopedic surgeon about which option is best for you. Each case is unique and should be evaluated thoroughly before making a final decision.  

What is the ACL?

There are four major ligaments in the knee. The ligaments attach three bones: the thighbone (femur), the shinbone (tibia) and the knee cap (patella). There are 2 groups of ligaments in the knee; the collateral ligaments and the cruciate ligaments. The anterior cruciate ligament or ACL is one of the cruciate ligaments.

The two collateral ligaments are known as the medial collateral ligament and the lateral collateral ligament. The medial collateral ligaments are on the side of the knee and control sideways motion of the knee. These bands of tissue are intended to protect the knee from extending too far to either side.

The two crutiate ligaments are known as the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). These two bands cross each other to form an “X”. The ACL is in the front and runs diagonally across the middle of the knee. The ACL and PCL keep the knee from moving too far forward or backward.

The ACL is the most commonly injured of all the ligaments in the knee. The ACL is key to providing stability in the knee and minimizing stress within the knee joint. When injured, surgery is typically required to recover from the injury. 

In future articles, we will discuss ACL injuries and injury prevention in greater detail. If you feel you may have injured your ACL it is extremely important to consult an orthopedic surgeon.

What is Runners Knee?

Runner’s knee or Patellofemoral pain syndrome (PFPS) is a condition where the cartilage under the knee cap begins to wear away. Running can cause irritation where the kneecap rests on thighbone, which causes pain. The pain can be sharp or a dull ache that does not go away.

Causes

Runner’s knee can result from a biomechanical issue or from weak quadriceps and tight hamstrings. Some common biomechanical issues are flat feet, high arches in the feet, size and placement of the patella and worn cartilage. Weak quadriceps can cause alignment issues, while tight hamstrings and calves can put pressure on the knee. Also, the repetitive, jarring motion of running can often be enough to cause runner’s knee.

Symptoms

Symptoms of runner’s knee include pain behind or around the patella. Pain may also be felt toward the back of the knee. Some report a feeling of the knee ‘giving out’ and others have cracking in the knee.

Runner’s knee is more common in women due to the q-angle (see previous post on q-angle) – wider hips, which results in a larger angle of the thighbone to the knee, putting more pressure on the kneecap. It is also a condition that tends to strike younger athletes.

Prevention

Run on softer surfaces and make sure you are wearing the correct shoes. Local specialty running stores can be a great resource to see that you are fitted properly. Orthotics can also be helpful in the prevention of runner’s knee. 

Strength training is another great way to prevent runner’s knee. Focus on strengthening the quadriceps, hamstrings and calves. By doing this, you will reduce pressure on your knees. Also, remember to stretch the hamstrings and calves as this will also help with prevention.

If pain occurs, cut back on your running and avoid activities that involve extensive knee bending. Giving the knee a rest is the best way to begin to heal. If the pain persists, see a doctor.