Patellar Tendinopathy: What It Is and How To Treat It

Do you have pain just below your knee cap when you squat? Does going downstairs make it worse? Does it hurt just to sit down into a chair? Does this pain keep you from pursuing your athletic endeavors? You may be experiencing patellar tendinopathy, a condition commonly experienced by relatively young male athletes and otherwise known as “jumper’s knee”. While this condition is mostly prevalent in basketball and volleyball players, even everyday fitness enthusiasts can find themselves struggling to complete the simplest of knee-dominant movements without pain.

What is patellar tendinopathy?

Patellar tendinopathy occurs when the tendon that connects the patella (knee cap) to the tibia (shin bone) becomes inflamed due to overuse from repetitive activities or repeated hard impacts. Pain is typically present with knee dominant movements, such as: descending stairs, squatting, prolonged sitting, and jumping. Weakness of muscles that control the knee can result in compensatory patterns that effect movement quality. Micro-failure of the tendon occurs and limits its ability to properly transmit force through the bone to the muscle.

Cook & Purdam described tendon injury as occurring in three distinct phases that fall into a continuum:

1. Reactive tendinopathy

2. Tendon disrepair

3. Degenerative tendinopathy

Reactive Tendinopathy

In the early stages of the process, the tendon experiences a non-inflammatory proliferative response to tensile or compressive overload. A short-term adaptation occurs in which the tendon thickens and increases in cross-sectional area. This is an abnormal response, as a normal tendon responds to load by increasing in stiffness.

Tendon Disrepair

As the tendon continues to attempt to repair itself, there is an increase in proteoglycan (protein) production due to the influx of cells in the extracellular matrix (ECM). The presence of extra proteoglycans disrupts the ECM and induces collagen separation. This stage is mostly associated with chronic conditions. This is the stage that we generally think of when we talk about tendinopathy.

Degenerative Tendinopathy

The final stage is characterized by areas of cell death in the tendon. Large areas of the ECM are disordered and filled with byproducts of matrix deterioration. There is heterogeneity throughout the tendon, with areas of varying pathology mixed with normal tendon tissue. There is little room for reversal of pathological changes at this stage. This stage is typically observed in the older person.

How to Reverse the Injury Process 

It is important that we begin restoring the injured tendon to a more normal physiological state quickly to avoid further degeneration. To do so, we need to load the tendon appropriately. But how do we properly load the tendon when load is the cause of pain?

Recently, multiple studies have shown that performing sub-maximal isometric contractions are superior to eccentrics in reducing pain, minimizing quadriceps inhibition, and improving tendon structure and function. An isometric contraction occurs when a muscle contracts but does not experience a change in length.

In a study of 6 volleyball players with patellar tendinopathy, the authors found that performing 5 rounds of 45 second isometric quadriceps contractions at 70% of the subjects 1-repetition maximum and 60o of knee flexion significantly reduced the subjects pain during a single leg decline squat when compared to isotonic contractions (Rio et. al., 2015). The same study found that cortical inhibition (the process in which inhibitory neurons selectively limit activity of other neurons in the motor cortex) was also reduced by isometric contractions when compared to isotonics.

A systematic review from 2018 found that high-intensity isometric contractions (³70% 1RM) were required to improve tendon structure and function. This study also found that no matter the intensity of the isometric contraction, substantial improvements in muscular hypertrophy and maximal force production were made.

How can I perform isometrics on my own?

If you have access to a gym, a good place to start is on the leg extension machine. The leg extension is ideal for performing sub-maximal isometrics. This is because you can isolate the quadriceps muscles and set the padded resistance bar at the appropriate position to limit knee extension. Pick a weight that cannot be moved with 70% of your max effort. Hold for 45 seconds and then rest for 1.5 – 2 minutes. Repeat 5 times.

An example of how to do this can be viewed in the video below.

If you do not have access to gym equipment like this, you can perform a simple wall sit instead! The same dosage listed above applies.

If you do have access to gym equipment, feel free to experiment with other exercises that target the quads. Leg press, lunges, etc. are good options to experiment with if you’re feeling ambitious.

If you have minimal access to equipment like heavy resistance bands, you can perform a Spanish Squat shown below.

Are isometrics the only exercise I need to perform? 

It depends. If you just want to reduce your pain and do not wish to return to a specific activity or sport, you are probably fine with only performing isometrics. If you wish to return to a specific sport or activity, it is essential that you expose the tendon to specific, graded activity so that your tissues are well prepared.

If you are looking for guidance in regards to Return to Sport/Activity Rehab, then come on in to Trifecta Therapeutics and schedule an evaluation!

Stephen Gibson, SPT

References:

Oranchuk, D. J., Storey, A. G., Nelson, A. R., & Cronin, J. B. (2019). Isometric training and long-term adaptations: Effects of muscle length, intensity, and intent: A systematic review. Scandinavian Journal of Medicine & Science in Sports, 29(4), 484–503. https://doi.org/10.1111/sms.13375

Patellar tendinopathy. Physiopedia. (n.d.). Retrieved May 5, 2023, from https://www.physio-pedia.com/Patellar_Tendinopathy?utm_source=physiopedia&utm_medium=search&utm_campaign=ongoing_internal#cite_note-:0-12

Rio, E., Kidgell, D., Purdam, C., Gaida, J., Moseley, G. L., Pearce, A. J., & Cook, J. (2015). Isometric exercise induces analgesia and reduces inhibition in patellar tendinopathy. British Journal of Sports Medicine, 49(19), 1277–1283. https://doi.org/10.1136/bjsports-2014-094386