Patellar Tendinopathy: Definition, Etiology, and Diagnosis

Patellar tendinopathy is a common condition seen in orthopedic clinics and a frequent diagnosis related to sports. Also known as Jumper's Knee, it is associated with sports that place demands on the knee extensor apparatus, such as basketball, cycling, athletics, soccer, or volleyball. Its average incidence is around 15%, and its prevalence can reach 30% (basketball) or even 40% in volleyball.

The most common site of involvement is located at the proximal junction of the tendon with the inferior pole of the patella (10% of cases will affect the quadriceps insertion on the superior pole of the patella). The initial symptoms will be pain in the inferior pole of the patella, with a sudden onset after or after jumping, or gradual onset after a training session or competition.

Its symptoms can sometimes be indistinguishable from the typical patellofemoral pain (pain when going up or down stairs, pain when sitting with a flexed knee, or when driving a car). The diagnosis will be clinical: pain upon palpation of the proximal insertion of the tendon to the lower pole of the patella with a history of pain in the same location during sports activities.

In growing patients, these tendinopathies usually present as osteochondrosis of the tibial insertion of the tendon (Osgood-Schlatter disease. If you would like to learn more about this condition, (visit /en/dr-jordi-jimenez/blog-take-care-of-your-health/osgood-schlatter-disease), or as osteochondrosis of the patellar insertion of the tendon in the lower pole of the otella (Sinding-Hansen-Johansson disease).

The cause of this tendon damage is unknown, with the most widely accepted theory being degenerative overuse, which leads to muscle stiffness with reduced extensibility of the muscle-tendon complex and a reduced capacity for rapid contraction, which increases traction on the tendon. The main causal factor is deceleration upon landing after a jump.

Factors that contribute to the development of patellar tendinopathy

Several factors can contribute to the development of this condition, which we will divide into:

1.-Intrinsic factors:

• biomechanical alterations and malalignments, such as foot pronation, tibia vara, femoral anteversion, etc.
• soft tissue stiffness
• muscle dysfunctions such as atrophy of the vastus medialis or adductors.

2.-Extrinsic factors:

• inappropriate footwear
• training surfaces
• excessive workload
• poor planning of training loads

Classification of patellar tendinopathy

Regarding diagnosis, a thorough history and physical examination will be essential to establish a diagnosis, supported by complementary tests such as X-rays, ultrasound, and MRI, although the latter may occasionally be normal.

The most widely accepted clinical classification for determining the functional implications of pain in patellar tendinopathy is the Blazina classification, which is as follows:

• Grade I: Pain after exercise.
• Grade II: Pain at the beginning of activity that disappears after warming up and reappears after exercise.
• Grade IIIa: Pain during and after activity that allows the athlete to participate in competitions and training at their usual level.
• Grade IIIb: Pain during and after activity that prevents the athlete from participating in competitions and training at their usual level.
• Grade IV: Complete rupture of the tendon

In the following post, we will discuss the acute and chronic phase treatment of patellar tendinopathy and preventive measures to avoid it.

Do you have pain in your knee? Make an appointment with Dr. Jordi Jiménez. He will see you in the center of Palma and help you regain your quality of life.