Quadricep tendinopathy or patellar tendinopathy can be referred to as Jumper’s knee as it is common in individuals that participate in jumping sports. The difference between these two tendons is that the quadricep tendon attaches from the bony kneecap to the quadricep muscle and the patellar tendon attaches from the bony kneecap to the tibia bone. A tendon has less stiffness the closer it is to muscle, whereas there is greater stiffness closer to bone. The quadriceps muscle will contract eccentrically when landing from a jump to absorb the impact. If the tendon was stiff close to the muscle and there was an inability for the muscle to lengthen, then there may be an increased risk of injury.
The patellar tendon has superficial and deep layers of tissue that run parallel to one another. The superficial layer is a continuation of the quadriceps tendon from the rectus femoris muscle. The quadricep tendon is complex and arises from four separate muscles. The three layers reflect the muscles they attach to: rectus femoris, vastus lateralis and medialis, and vastus intermedius. Because these muscles have a unique line of action, the quadriceps tendon is subjected to nonuniform load and shear forces, where the parallel structure of the patellar tendon makes it more uniform.
Frequently Asked Questions
What is patellar tendinopathy vs quadricep tendinopathy?
Patellar tendinopathy is pain at the inferior pole of the patella (bottom of kneecap) where the majority of elite jumping athletes will experience these symptoms. Extreme forces including acceleration and deceleration, jumping and landing can lead to patellar tendinopathy. Quadriceps tendinopathy is pain at the superior pole of the patella (top of kneecap) where it attaches to the quadriceps muscle, these symptoms are worsened with deep knee flexion. An acute incident where high levels of eccentric quadriceps loading that occurs with knee flexion with landing is the most common mechanism of injury.
How is patellar tendinopathy and quadriceps tendinopathy diagnosed?
A thorough history and physical examination is taken including where is the pain, how did the injury occur and what aggravates symptoms. Typically someone will point to the tendon as being the source of pain – so quite localised rather than diffuse pain presentation. Tenderness on palpation of the affected area, as well as swelling, can help identify tendinopathy. For patellar tendinopathy, special tests may include single leg decline squat test, jumper’s knee test or step down test. For quadriceps tendinopathy, special tests may include resisted knee extension test, active straight leg raise test, isometric quadriceps contraction, or single leg hop test.
Although not necessary, diagnostic imaging can be conducted to rule out other pathologies. An ultrasound can show thickening or partial tears of the tendon, though an MRI can show a more detailed view of the tendon and any degeneration present.
What is the evidence-based treatment for patellar tendinopathy and quadriceps tendinopathy?
A period of activity modification and graded exposure to load applies to all tendinopathies – rest is not best for an irritable tendon. All tendinopathies are overuse injuries where the affected tendon is overloaded and does not have adequate capacity to deal with the loads. With greater loads, there is greater pain and typically the quadriceps tendon will experience greater loads than the patellar tendon. An exercise program for quadricep tendinopathy may include end-range deep knee flexion to maximise loading of the quadriceps tendon and tibial rotation and hip extension can alter the loading of the quadriceps muscles, targeting the affected layer.
For patellar tendinopathy, a period of rest or activity modification is necessary to reduce load on the patellar tendon. This involves avoiding deep knee flexion, running and jumping. A gradual progression back to these activities will occur through graded exposure and a progressive overload program aimed at the knee joint. Exercises begin with eccentric partial weight-bear loading of the patellar tendon and strengthening of the hip and knee. Soft tissue mobilisation can be used to reduce pain in early rehabilitation. Once pain has decreased and is manageable, exercises can be progressed to full weight-bearing and weighted resistance. Following this, jumping and other dynamic movements can be reintroduced to prepare for a return to sport, or normal activities.
Corticosteroid injections can negatively affect tendon strength and can lead to tendon rupture. Therefore, these injections are not advised in the management of patellar tendinopathy.
As patellar tendinopathy and quadriceps tendinopathy are overuse injuries, rapid progression should be avoided to limit exacerbation of symptoms.