Depending on the duration of symptoms, jumper's knee can be classified into 1 of 4 stages:
- Stage 1 - Pain only after activity, without functional impairment
- Stage 2 - Pain during and after activity, although the patient is still able to perform satisfactorily in his or her sport
- Stage 3 - Prolonged pain during and after activity, with increasing difficulty in performing at a satisfactory level
- Stage 4 - Complete tendon tear requiring surgical repair
The cause of jumper's knee remains unclear. Tissue specimens don’t usually show inflammation, which is more commonly seen in a true tendonitis. Since the 1970’s, this has been thought to be more of a tendinosis, which is tendon injury without inflammation. Biomechanical research has shown that a greater mechanical and tension load is borne by the anterior (front-side) fibers of the patellar, or kneecap, tendon, which produces the typical symptoms and physical exam findings.
- The diagnosis of jumper's knee is based on the history and clinical findings. Laboratory tests are rarely needed. They may, though, be considered if other problems, such as infection, could be causing the joint problem.
- X-ray imaging is usually not needed, but it could be helpful for making the diagnosis or excluding other potential causes.
- Ultrasonography and MRI are both highly sensitive for detecting tendon abnormalities in both symptomatic and asymptomatic athletes.
Most patients respond to a conservative management program such as the one suggested below.
- Activity modification: Decrease activities that increase kneecap and upper leg pressure (for example, jumping or squatting). Certain "loading" exercises may be prescribed.
- Cryotherapy: Apply ice for 20 to 30 minutes, 4 to 6 times per day, especially after activity.
- Joint motion and kinematics assessment: Hip, knee, and ankle joint range of motion are evaluated.
- Stretching: Stretch (1) flexors of the hip and knee (hamstrings, gastrocnemius, iliopsoas, rectus femoris, adductors), (2) extensors of the hip and knee (quadriceps, gluteals), (3) the iliotibial band (a large tendon on the outside of the hip and upper leg), and (4) the surrounding tissues and structures of the kneecap.
- Strengthening: Specific exercises are often prescribed.
- Other sport specific joint, muscle, and tendon therapies may be prescribed.