Anterior Knee Pain Syndrome
(Patello-Femoral Syndrome and Chondromalacia Patella)

Introduction

These are all name for the same problem and they are used interchangeably. Chondromalacia patella literally translates to chondro or cartilage, malacia or bad, and patella or kneecap all put together “bad cartilage on the kneecap”.  This is one of the most common reasons for knee pain.  The pain is usually in the front of the knee, but it can be diffuse.  It can vary in severity from a mild discomfort to a sharp disabling pain.

Anatomy

The patella is encased in tendons (tissue that attaches muscle to bone) and ligaments (tissue that attaches bone to bone) and it articulates with a groove in the femur or thighbone called the trochlear groove.  The tendons and ligaments control the motion of the patella.  The trochlear groove is the “track” in the femur where the patella moves.  The three functions of the patella are protection of the knee joint, extra leverage for the quadriceps muscles to straighten the leg, and improve the cosmetic look of the knee.

Symptoms

Pain is the most common complaint.  The pain is usually worse when walking up or down hills and stairs, squatting, kneeling, and sitting with the knees bent for long periods of time.  There may be a feeling of grinding or creaking under the patella.  An effusion (fluid inside the knee joint) may be present.  The knee may feel unstable or it wants to “give-out”.  Or there may be some stiffness.

Causes

Trauma is a known cause of chondromalacia patella.  However, the exact mechanism of injury is frequently not known.  Some of the other contributing factors are:

Repetitive flexion activities such as kneeling, crawling, squatting, and stair climbing.

Tightness, imbalance or weakness of the thigh muscles.

The hamstring muscles are too tight (not flexible enough).

The femoral neck is turned too far forward (femoral anteversion).

The angle between the femur and the tibia is too large, “knock-kneed” (genu valgum).

The foot is rotated out (external tibial torsion) too much.

The forefoot is overly pronated (the arch is flattened).

All of the above stresses on the knee, and the patella in particular, may eventually cause the articular cartilage to breakdown. Damaged cartilage has a limited ability to heal and will progress first from softening, quickly to fraying, then cracks, and then cartilage loss. Damaged cartilage can’t distribute pressure evenly and this leads to more stress on the bone.    Pain is caused by the abnormal stress on the bone and by the inflammation this causes.

Prevention

Stay in shape: Good general conditioning is important. If you’re too heavy, you need to lose weight. (The knee experiences 4-10 times body weight during activities such as walking and going up and down stairs.)

Exercises: Both stretching and strengthening are important in helping to keep the stress on the patello-femoral joint under control. It is important that the muscles of the back and legs are well “balanced.”

Training: Avoid sudden changes in your workouts. Gradually increase the intensity and duration of your activities and exercises.

Foot wear: Running shoes should have good shock absorption and be changed every 300-500 miles of use. Other shoes should be well maintained and appropriate for your activities. Shoe inserts may be needed for certain foot types.

Proper form: It is not enough to just exercise/train. It is important to do them correctly. Please check with a professional to make sure your form is not causing some of your problems.

Diagnosis

The diagnosis of chondromalacia patella can really only be made by directly looking at the patella.  However, a very reliable diagnosis of chondromalacia patella can be made with a good history and physical exam.  X-rays, MRI, a bone scan, and possibly other tests can be very useful.

Medical History: This is used to determine the type of problem/pain, its severity, and what the cause may be. Important information will include; “When did the pain start?”, “What activities aggravate the pain?”, “What makes the pain better?”

Physical Examination: This is used to help pinpoint the possible muscle, bone, tendon, ligament, and alignment abnormalities that may be contributing to the problem.

Diagnostic Tests: These are used to help determine the extent of tissue damage and abnormality. 

The cartilage damage is graded for its severity at surgery.  One of the most commonly used grading systems has the following grades: Grade I is softening of the cartilage.  Grade II is fraying of the cartilage with small cracks.  Grade III is when there are deeper cracks with partial loss of cartilage thickness.  Grade IV is when there is full loss of cartilage and bone is exposed.

Treatment

The treatment plan developed by your physician will try to reduce the pressure between the patella and the trochlear groove.  The plan may change slightly from one patient to another and is based on the cause of the Anterior Knee Pain Syndrome if it can actually be determined.

Conservative (non-surgical) treatment options may include Tylenol or NSAID (such as Advil or Aleve), bracing, exercises and/or Physical Therapy (PT), orthotics, activity modification, and injections.  Tylenol and/or NSAID are used to help reduce pain and swelling.  Bracing helps the patella move better inside the trochlear groove.  Exercises and/or PT help to regain an appropriate amount of strength, flexibility, and the balance of the muscles around the knee.  Orthotics can be helpful if there is an abnormal alignment of the foot.  And, injections may help reduce inflammation, swelling and pain.  Conservative care may take as much as 1 to 2 years to demonstrate significant benefits. 

There are three “phases” that you must go through in conservative treatment.  The amount of time each phase will take varies from one person to the next and the phases may overlap slightly.  The first phase is the “Pain Reduction Phase.”  In this phase, we will try to work with you to reduce your pain.  The second phase is the “Rebuilding Phase.”  In this phase, we or a therapist or athletic trainer will guide you through workouts to build muscle and flexibility.  The third phase is the “Functional Phase.”  In this phase, we or a therapist or athletic trainer will guide you back to activities.  There is no way to know what activities you will be able to participate in when you have reached maximal healing.  If conservative care is “unsuccessful” (as determined by you and your doctor), surgery may be considered. 

There are a number of surgical options for chondromalacia patella if conservative treatment has failed.  However, the response that patients get from surgery varies from complete relief to no relief at all.  In addition, if relief is obtained, there is no good way to know how long it will last.  Of all the procedures done, arthroscopy is the simplest with the fewest complications.  The arthroscopy is first a diagnostic tool in that it helps the surgeon determine the full extent and location of the problem.  Second, the surgeon can smooth out the cartilage surface and possibly release some tissue that can relieve some of the patellofemoral pressure.  Other surgeries are more extensive, but under the right circumstances can be very helpful. You will need to discuss these further with your doctor.

In all, Anterior Knee Pain Syndrome is a problem of the knee that won’t go away easily or quickly.  It requires quite a lot of time and energy on the patient’s part to make this problem improve.  In addition, it is important to remember that this problem never really goes away and will always require some level of care.

Written by James A. Shapiro, MD