context: Background The term jumper's knee was first used in 1973 to describe an insertional tendinopathy. That's a tendon injury seen in athletes at the point where the tendon attaches to bone. Jumper's knee usually involves the attachment of the kneecap tendon to the lower kneecap pole. Jumper's knee refers to functional stress overload due to jumping. Frequency United States Jumper's knee is one of the more common tendinopathies affecting athletes with mature skeletons. It occurs in as many as 20% of jumping athletes. With regard to bilateral tendinopathy (both sides), males and females are equally affected. With regard to unilateral tendinopathy (one side), twice as many males as females are affected. Sport Specific Biomechanics Jumper's knee is believed to be caused by repetitive stress placed on the patellar or quadriceps tendon during jumping. It is an injury specific to athletes, particularly those participating in jumping sports such as basketball, volleyball, or high or long jumping. Jumper's knee is occasionally found in soccer players, and in rare cases, it may be seen in athletes in non-jumping sports such as weight lifting and cycling. Risk factors include gender, greater body weight, being bow-legged or knock-kneed, having an increased angle of the knee, having an abnormally high kneecap or an abnormally low kneecap, and limb-length inequality. Impairment linked to jumper's knee includes poor quadricep and hamstring flexibility. Vertical jump ability, as well as jumping and landing technique, are believed to influence tendon loading. Overtraining and playing on hard surfaces have also been implicated as risk factors. Interestingly, the kneecap tendon experiences greater mechanical load during landing than during jumping, because of the eccentric (off center) muscle contraction of the quadriceps. Therefore, eccentric muscle action during landing, rather than concentric (symmetrical) muscle contraction during jumping, may exert the mechanical and tension loads that lead to injury. History Jumper's knee commonly occurs in athletes involved in jumping sports such as basketball and volleyball. Patients report front side knee pain, often with an aching quality. Symptoms sometimes come on slowly and may not be associated with a specific injury. 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 Causes 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. Physical Therapy 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. Ultrasound or phonophoresis (ultrasound delivered medication) may decrease pain symptoms. A special brace with a cutout for the kneecap and lateral stabilizer or taping may improve patellar tracking and provide stability. Sometimes arch supports or orthotics are used to improve foot and leg stability, which can reduce symptoms and help prevent future injury. The treatment of jumper's knee is often specific to the degree of involvement. Stage 1 Stage I, which is characterized by pain only after activity and no undue functional impairment, is often treated with cryotherapy. The patient should use ice packs or ice massage after terminating the activity that exacerbates the pain and later again that evening. If aching persists, a course of regularly prescribed anti-inflammatory medications should be administered for 10 to14 days. Stage II In stage II, the patient has pain both during and after activity but is still able to participate in the sport satisfactorily. The pain may interfere with sleep. At this point, activities that cause increased loading of the patellar tendon (for example, running or jumping) should be avoided. A comprehensive physical therapy program, as discussed above, should be implemented. For pain relief, the knee should be protected by avoiding high loads to the patellar tendon, and cryotherapy should continue. The athlete should be instructed in alternative conditioning to avoid injury to the affected area. Once the pain improves, therapy should focus on knee, ankle, and hip joint range of motion, flexibility, and strengthening. If the pain becomes increasingly intense and if the athlete becomes more concerned about his or her performance, a local corticosteroid injection may be considered. The doctor will explain the pros and cons of these injections. Stage III In stage III, the patient's pain is sustained, and performance and sport participation are adversely affected. Though discomfort increases, therapeutic measures similar to those described above should be continued along with not participating in activities that may worsen or prevent recovery from the injury. Relative rest for an extended period (for instance 3 to 6 weeks) may be necessary in stage III. Often, the athlete will be encouraged to continue an alternative cardiovascular and strength-training program. If the condition does not improve with treatment, surgery may be considered. Some athletes will not be able to continue to participate in activities that worsen or prevent recovery from the problem. Stage IV Tendon rupture requires surgical repair. Medical Issues and Complications Knee immobilization is not recommended because it results in stiffness and may lead to other muscle or joint problems, further prolonging an athlete's return to activity. Consultations Consultation with a physical medicine and rehabilitation specialist or an orthopedic specialist is recommended, particularly for Stage I cases that do not respond to conservative treatment and more severe cases ( Stages II, III, and IV). Primary care sports medicine physicians can also be consulted. Recovery Phase Physical Therapy An in-depth, stage-specific description of a conservative therapy program is described above. In brief, in the recovery phase, the athlete and therapist should work to restore pain-free joint range of motion and muscle flexibility, symmetric strength in the lower extremities, and joint sensation. Sport-specific training, including high-level sport specific exercises, should then be initiated. Consultations Consultation with a physical medicine and rehabilitation specialist or an orthopedic specialist is recommended, particularly for Stage I cases that do not respond to conservative treatment or more severe cases ( Stages II, III, IV). Surgical Intervention Surgical intervention is indicated for stage IV, and refractory stage III tendinopathy as noted above. Maintenance Phase Rehabilitation Program Physical Therapy An in-depth, stage-specific description of a conservative therapy program is described above (see Acute Phase). Briefly, once in the maintenance phase, the athlete should complete a sport-specific training program before returning to competition. The physician and physical therapist can assist the athlete in determining when to return to competition based on the patient's symptoms, current physical examination findings, and functional test results. Once the athlete returns to play, he or she must work to maintain gains in flexibility and strength. Consultations Consultation with a physical medicine and rehabilitation specialist or an orthopedic specialist is recommended, particularly for Stage I cases that do not respond to conservative treatment or more severe cases ( Stages II, III, IV). Surgical Intervention Surgical intervention is indicated for stage IV disease. See Acute Phase above. Non-steroidal anti-inflammatory drugs are often used for pain and inflammation control. Drugs in this category include naproxen ( Naprosyn, Aleve), ibuprofen ( Motrin, Advil) and others. These should be used per the doctor's instruction and according to label directions. People with certain conditions should not use these medications. Your doctor will help you know if these drugs are right for you. Return to Play Return to play should be based on an athlete's ability to safely and skillfully perform sport-specific activities. When symptoms persist despite conservative or surgical treatment, the athlete must weigh the benefits and the consequences of playing in pain or chances of re-injury. Functional testing at the end of the recovery phase of rehabilitation, administered by a physical therapist, athletic trainer, or physician, is helpful in determining the athlete's readiness to return to his or her sport. The doctor will help to determine whether it is safe or not to resume activities. Complications The most common complication is persistent pain during jumping. Re-injury or worsening of the problem is also possible. Prevention Sport-specific training and physical fitness prior to competition may help prevent jumper's knee. Prognosis The prognosis for jumper's knee stage I or II is typically excellent with conservative treatment. Stage III carries a guarded prognosis for a full-recovery, while those few with stage IV injury (complete tendon rupture) require surgical repair of the tendon and are least likely to return to competitive play. Education Jumper's knee affects jumping athletes. It is nearly always amenable to conservative treatment with a comprehensive rehabilitation program. The persistence of pain during and after play guides the staging and treatment of this problem. Use of relative rest, reducing pain and inflammation, and alternative conditioning methods help to improve the chances of an athlete's return to competition. The doctor will help in deciding what activities are appropriate.