Knee surgeon

Patellofemoral or knee cap


What problems can we find in the patellofemoral joint?

There are basically two: pain and instability, although sometimes they can be seen as interconnected.

The patellofemoral pain syndrome or anterior knee pain manifests as pain in the anterior aspect of the knee and is reckoned to generate 50% of all knee pain. Although the origin of this pain is not well known, it is thought that it is generated by irritation of the synovial tissue that surrounds the joint. 

The patella or kneecap is a bone that has very special characteristics. It is supported at all its edges by muscles and ligaments, sliding into the trochlear groove. 

Patellofemoral instability occurs when this mobility is abnormally increased and may or may not cause pain. In other words, when the tracks are arranged irregularly, or the train (the kneecap) has characteristics that do not match very well on those tracks.

Anterior knee pain

The pain is generated after an increase in pressure between the patella and the trochlea. The more the knee is flexed, especially if done loading weight on it, the greater the pressure that can generate irritation and wear on the articular cartilage. That is why this pain presents so characteristically upon coming down or climbing stairs or by spending a great deal of time with the knees bent.

Predisposing factors

Although the pain starts spontaneously for no apparent reason in a high percentage of patients, there are factors that predispose to the patellofemoral pain syndrome in most cases:


There is very little pressure between the patella and femur when the knee is extended or minimally bent. Therefore, the best activities are those that limit flexion to 45°.  

Good sports:

They are those that most people can do without pain or discomfort

Questionable sports

They are those that some people can do but generate pain or discomfort in others.

Harmful sports

Son realmente malos para el dolor femoropatelar.


It is based on two principles: reduce inflammation and improve the dynamic between the patella and femur. 


Only in those cases of a painful and swollen knee. The pain should be the guide for the conduct of activities. Some discomfort or bother is not a problem, rest only when there is pain.


It is recommended in the initial periods, especially at the end of the day or sports activity. It should be applied for about 15 minutes each time.

Nonesteroidal anti-inflammatories drugs

With the same objective as rest and ice, that is, to reduce inflammation and pain.

In summary:


The essential element of any treatment of patellofemoral pain. Up to 95% of patients improve with correctly performed rehabilitation. Keep in mind that if the thigh muscles are strong, the patella will move within the trochlear groove with less pressure. Unfortunately, it is usual to see them being done improperly as well as the lack of continuity with the exercises by patients. In general, the lack of detailed medical information generates an incorrect execution of the exercises by the patient that does not yield any improvement. This generates disappointment that leads patients to abandoning the routines. 

Exercises should be done at least 3 times a week with maximum intensity, about 45-60 minutes per session. There are five essential types of exercises to execute:

  • Isometric quadriceps
  • Hamstring stretches
  • Hip external rotators
  • Core
  • Propiocepción


Access to the videos for exercises.

Femoropatelar instability

Patellofemoral instability occurs when the mobility of the patella is abnormally increased and may or may not cause pain. The patella has a complex movement as it slides at different degrees of knee flexion on the trochlea or femoral groove. It may be that it has an abnormal shape, or that the kneecap is not centered on it. In other words, when the tracks (femoral slide or trochlea) are arranged irregularly, or the train (the kneecap) has characteristics that do not match very well with each other.

Predisposing factors

In most cases there are factors that predispose to patellar or patellofemoral instability:


A percentage of patients will need surgery to treat the pain and/or patellofemoral instability. This is generally indicated in the case of pain that has failed to improve after 3 to 6 months of correctly performed exercises. In cases of instability, surgical treatments are recommended sooner. It is considered that in the event of a second episode of dislocation, the most appropriate would be a surgical correction, because each episode generates irreparable damage to the articular cartilage. There are even cases where surgery is recommended for just the first episode of dislocation

The choice of the multiple available surgical techniques to be performed is based on the specific alterations of each patient:

These are determined through physical examination and through radiological studies such as torsional computed tomography and standard radiology. The role of MRI in patellofemoral pathology is also essential to determine elements such as cartilage wear and other associated injuries.

Given the observed changes, surgical options are usually found among:

Each of these techniques can be done alone or concomitantly with others.

Medial patellofemoral reconstruction is currently considered the crucial step in any patellar instability surgery. It may be associated to additional surgical techniques. However, this ligament needs to be always reconstructed

Dr. Gelber uses an innovative, differential medial patellofemoral ligament reconstruction technique that has widely demonstrated it outstanding results. He has also published several scientific studies on this topic. This technique allows complete sports return only 3 months after surgery, as opposed to 6-8 months for the rest of the techniques used by the vast majority of surgeons.

The different can see what is invisible to others.


Before the surgery

Dr. Gelber evaluates the knee through clinical tests, x-rays, magnetic resonance imaging, and a torsional study with tomography to determine the origin of the problem and what alterations need to be corrected. For the diagnostic and therapeutic discernment between the different degrees of injury and specifically which alterations should or should not be corrected, precision and experience are required. All of this is explained in detail to the patient for their complete understanding of the injury.

After surgery

On the day of discharge from the hospital and before going home, the patient receives all the necessary information regarding postoperative care and leaves the hospital with an appointment approximately 10 days later to review the surgical wound and remove the stitches.


The type of rehabilitation varies depending on the surgery performed, but it always focuses on the same principles described previously, with strengthening of the quadriceps, core and hip rotators, and with muscle stretching, especially of the hamstrings (see videos). Most patients obtain almost complete functional improvement between 3 and 6 months, although minor additional progress is expected up to one year after the intervention.

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