The Patellar Tendon

The patellar tendon is an extremely functional tendon that connects the patella (kneecap) to the tibia (shin bone). In reality, it is a continuation of the quadriceps muscle, so sometimes you may see patellar tendon and quadriceps tendon used interchangeably. Some people like to categorize the regions of the tendon, whereby the consider the part above the patella to be the quadriceps tendons, and the part below the patella to be the patellar tendon. Given the tendon connects the tibia to one of the strongest muscle groups in the body, it has to be robust and strong enough to take on this responsibility.

So why does the patella have to be involved at all? Why isn't there just one continuous tendon emerging from the quadriceps muscle that attaches directly to the tibia? The answer is two-fold. First, the patella offers protection for the knee joint capsule. Think how many times you have fallen on or banged your kneecap against something. Second, the patella offers mechanical leverage, making the movement of knee extension much more efficient, providing more strength in the process.

Light Red = Line of pull without knee cap.
Dark Red = Line of pull with kneecap.

Patellar Tendon Injuries

Patellar Tendinitis (a.k.a. Jumpers Knee)

Patellar tendinitis, or jumpers knee, is a very common overuse injury that anyone can develop, but sports that involve lots of repetitive jumping can predispose an individual to a higher risk of developing this condition. Repetitive stress, especially when the level of stress is high (e.g. jumping), will cause tiny tears to form in the tendon. At first, this may not be a problem, but as the tears accumulate and the tendon tries to keep up with repairs, you can end up with a combination of damage from the tears and inflammation from the constant ongoing healing process.

At first, patellar tendinitis may only manifest itself during activity, whereby you only feel slight pain when performing activities like intense exercise or jumping. As the condition progresses, pain will become more recurrent, and it may also intensify. If left totally untreated, it could eventually get to the point where you experience pain and stiffness from simple tasks like walking or climbing stairs.

By simultaneously strengthening other muscles, those muscle can take on some of the load previously placed upon the patellar tendon. While these are the preferred treatment options, they are only effective to a certain extent, beyond which more severe cases may require corticosteroid injections, or in the worst case, surgery. If the patellar tendinitis has persisted for quite some time, many health care professionals would term this patellar tendinopathy.

So how does a patellar tendonitis strap help with symptoms associated with this condition? After all, the design of these straps seem extremely simple. Fortunately, this simple design is actually highly effective. Basically, it works by placing pressure directly over the patellar tendon. This acts to redistribute the internal forces away from the tendon, so it experiences a lower degree of stress. This won't necessarily treat the condition completely, but it can certainly help you maintain your level of activity while you treat the patellar tendinitis.

For more information about general stretching and strengthening techniques for patellar tendonitis, check out this great demonstration courtesy of Strength Side.

Osgood-Schlatter Disease

Osgood-Schlatter disease is actually pretty similar to patellar tendinitis, but with two main differences. First, this disease is typically limited to growing adolescents. Secondly, the affected region is usually the interface of the patellar tendon and the tibia, not simply tears within the tendon itself.

Like patellar tendinitis, this disease is more common in adolescents who are involved in sports, especially ones that involve lots of jumping. It used to be thought that boys were more predisposed to this, but the constantly narrowing gender gap suggests this was simply a result from boys having previously participated in sports more than girls, which is not always the case now. The pain involved is similar to patellar tendinitis, but different individuals will experience different levels of pain, from pain only during activity, to almost constant and extreme pain no matter what the situation.

As the tendon repeatedly pulls on the the tibia in adolescents, it can gradually weaken the interface, almost lifting off from the bone, but not completely separating. Given that adolescents are actively growing, the bone can repair itself by adding more bone to the damaged area, which acts as an attempt to catch up with the tendon and restore the connection. This can result in a bony lump at the top of the shin bone, which is a telltale sign of Osgood-Schlatter disease.

Treatments for Osgood-Schlatter disease are actually quite minimal, as the disease should regress as soon as the adolescent's bones stop growing. In the mean time, patellar tendon straps can help reduce the pain during activity, physical therapy (focus on stretching and strengthening) can help reduce some of the stress placed upon the tendon, and mild pain relievers and NSAID's, like Tylonel and Advil, can help reduce the pain.

Patellofemoral Pain Syndrome (PFPS)

Patellofemoral pain syndrome (PFPS) occurs most often in runners, as well as people who do lots of squats, or make drastic changes to their physical activity levels. It's a fairly mysterious condition, which is why the word "syndrome" is still in use when describing it. While many underlying causes have been discovered, it still remains a tricky condition to treat.

Like patellar tendinitis, PFPS can result from simple overuse of the knee joint, especially when it is being placed into flexion where the quadriceps muscles are being lengthened and contracting at the same time (eccentric contraction), thus placing a lot of stress on the patella and its associated tendon.

One of the more recently discovered mechanisms of PFPS results from patellar misalignment, as well as patellar tracking in the lateral directions. Instead of moving nicely up and down in the patellar along the patellar track, imbalances in muscle strength and flexibility, particularly in the vastus lateralis (outside portion of quadriceps), can cause the patella to shift around as it moves up and down, irritating the patella and surrounding structures. This can also lead to an unbalanced knee joint overall, and therefore the pain can extend to many different anatomical structures.

Pain is the most common symptom and generally arises during activity that involves bending the knees. Other symptoms include pain after long periods of sitting, pain related to a change in activity or setting of the activity, or popping and cracking sounds in the knee after long periods of sitting or while climbing stairs. Of course, these symptoms are present in many other conditions as well, which makes PFPS sometimes difficult to identify right away.

There are a variety of treatments, including home remedies that involve resting the knee with ice and in an elevated position, as well as simple over-the-counter pain medications. Physical therapy can also be effective by restoring balance to the knee joint through strengthening and stretching, and in some cases, orthotics can help as well. Like most conditions, the worst case scenario is surgery, but this has shown a decent level of success.

What about knee straps? Some people find they work, others don't. Success likely depends on the exact conditions, the degree to which it has advanced, where activity is being performed, as well as individual anatomy. Some studies have shown that using knee straps just below AND just above the knee can help delay the onset of vastus lateralis contraction, which in some specific cases, could help alleviate PFPS pain. However, research is still in the early stages, so if you suspect you have PFPS, it's best to get diagnosed on an individual level through consulting with your doctor and physiotherapist.

Summary

Given the importance of a well-functioning patellar tendon, it's best to address any issues you are having as soon as possible. This will help save you a lot of pain and recovery time in the long run, allowing you to stay as healthy and active as possible. These aren't the only problems that can arise. For example, full on patellar tendon ruptures are more than possible, but the ones described above are the most common and tend to occur over a gradual period of time that leaves you wondering whether or not you should get it checked out. At the end of the day, it's always best to play it safe.

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