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What is Jumpers knee?
Jumpers knee is an accepted term for patellar tendinitis. It is common in high jumpers and volleyball or basketball players. This injury is characterized by pain at the inferior pole of the patella at its attachment to the patellar tendon.
It occurs as a result of repetitive stress whose frequency of occurrence exceeds the body’s rate of natural repair or healing.
Jumper’s knee is characterized by pain at the inferior or superior pole of the patella; it occurs in 20% of jumping athletes at some point in their careers.
The pain may affect one or both knees and affects men twice as commonly as women when just one knee is affected. It is usually the result of overuse or misuse of the knee joint, such as running, jumping, or overtraining on hard surfaces, or direct trauma to the quadriceps or patellar tendon from kicks or head butts during football or kickboxing.
Weak or poor quadriceps and hamstring muscle flexibility and congenital variants of the anatomy of the knee, such as patella alta or baja and limb length discrepancies, also have been implicated as risk factors for the development of jumper’s knee.
Jumper’s knee is a repetitive stress disorder that causes tendinosis of the quadriceps and patellar tendons and is a clinical entity distinct from tendinitis of the quadriceps or patellar tendons or quadriceps expansion syndrome, which may coexist with jumper’s knee and confuse the clinical picture. It is postulated that the strong eccentric contraction of the quadriceps muscle to strengthen the knee joint during landing is the inciting factor during jumping, rather than the jump itself. The quadriceps tendon also is subject to acute calcific tendinitis, which may coexist with acute strain injuries and the more chronic changes of jumper’s knee. Calcific tendinitis of the quadriceps has a characteristic radiographic appearance of whiskers on the anterosuperior patella.
Patients with jumper’s knee have pain over the superior or inferior pole (or both) of the sesamoid. In contrast to quadriceps expansion syndrome, which has a predilection for the medial side of the superior pole of the patella, jumper’s knee affects the medial and the lateral sides of the quadriceps and the patellar tendons. The patient notes increased pain on walking down slopes or down stairs. Activity using the knee, especially jumping, worsens the pain; rest and heat provide some relief. The pain is constant and is characterized as aching. The pain may interfere with sleep.
What are the Symptoms of Jumpers knee
On physical examination, tenderness of the quadriceps tendon or patellar tendon or both is noted, and a joint effusion may be present. Active resisted extension of the knee reproduces the pain. Coexistent suprapatellar and infrapatellar bursitis, tendinitis, arthritis, or internal derangement of the knee may confuse the clinical picture after trauma to the knee joint.
How is Jumpers knee diagnosed?
Plain radiographs are indicated in all patients with knee pain. Based on the patient’s clinical presentation, additional tests may be indicated, including complete blood count, erythrocyte sedimentation rate, and antinuclear antibody testing.
Magnetic resonance imaging (MRI) and ultrasound imaging of the knee are indicated if jumper’s knee is suspected, because they readily show the tendinosis of the quadriceps or patellar tendons responsible for this common pain syndrome. Bone scan may be useful to identify occult stress fractures involving the joint, especially if trauma has occurred.
Differential Diagnosis
The most common cause of anterior knee pain is arthritis of the knee; this should be readily identifiable on plain radiographs of the knee and may coexist with jumper’s knee. Another common cause of anterior knee pain that may mimic or coexist with jumper’s knee is suprapatellar or superficial and deep patellar bursitis. Internal derangement of the knee or torn medial meniscus also may confuse the clinical diagnosis, but should be readily identifiable on MRI of the knee.
Treatment
Initial treatment of the pain and functional disability associated with jumper’s knee should include a combination of nonsteroidal antiinflammatory drugs (NSAIDs) or cyclooxygenase-2 (COX-2) inhibitors and physical therapy. Local application of heat and cold also may be beneficial. For patients who do not respond to these treatment modalities, injection of the suprapatellar and infrapatellar space with a local anesthetic and steroid may be a reasonable next step.
Clinical studies suggest that injection of platelet rich plasma may aid in tendon healing. Ultrasound guidance may improve the accuracy of needle placement and decrease the incidence of needle-related complications.
Clinical reports have also suggested that ultrasonic tenotomy as well as injection with botulinum toxin may provide symptomatic relief. Rarely, surgical treatment will be required to provide symptomatic relief or to repair ruptured tendons.
Complications and Pitfalls
The major complication of injection of jumper’s knee is infection. This complication should be exceedingly rare if strict aseptic technique is followed.
Approximately 25% of patients report a transient increase in pain after injection of the quadriceps tendon of the knee, and patients should be warned of this possibility. The clinician also should identify coexistent internal derangement of the knee, primary and metastatic tumors, and infection, which, if undiagnosed, may yield disastrous results.
Clinical Pearls
Injection of the knee is extremely effective in the treatment of pain secondary to the previously mentioned causes of jumper’s knee.
Coexistent bursitis, tendinitis, arthritis, and internal derangement of the knee may contribute to the patient’s pain and may require additional treatment with more localized injection of local anesthetic and depot steroid preparation. Injection of jumper’s knee is safe if careful attention is paid to the clinically relevant anatomy in the areas to be injected.
Care must be taken to use sterile technique to avoid infection; universal precautions should be used to avoid risk to the operator. The incidence of ecchymosis and hematoma formation can be decreased if pressure is placed on the injection site immediately after injection.
The use of physical modalities, including local heat and gentle range-of-motion exercises, should be introduced several days after the patient undergoes this injection technique for tibiofibular pain.
A patellar strap may help provide symptomatic relief. Vigorous exercises should be avoided because they would exacerbate the symptoms. Simple analgesics and NSAIDs may be used concurrently with this injection technique.
