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Jumper's Knee Print

Jumper's Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Sports Medicine, Figure 1

Anterior knee pain in the athlete can be a difficult problem for the sports medicine physician to treat given the numerous causes and refractory nature. Although the symptoms are often vague, many athletes develop discrete pain over the various anatomic structures of the knee which helps lead toward a diagnosis.

The patellar tendon is a large tendon connecting the patella to the anterior tubercle of the tibia. It is the continuation of the quadriceps muscle and functions to transmit the pull of the quads to the tibia, resulting in extension of the knee. Some athletes involved in jumping sports develop pain at the junction of the patella and patellar tendon, the so called "jumper's knee". This condition results from repeated trauma to the area from repetitive forceful contraction of the quads required in jumping sports such as basketball and volleyball. Athletes generally complain of gradual onset of pain at the inferior border of the patella that is exacerbated by activity.

The pain is usually caused by multiple small tears that develop in the tendon from the repeated trauma. The tears usually occur at the tendon's attachment to bone since the tendon is stiffer and less vascular in this area, predisposing it to trauma. These small tears undergo degeneration and discrete areas of pain develop.

Physical Examination

Patients usually present with tenderness localized to the patellar tendon that is exacerbated by activity. They often report a gradual onset of symptoms and can not relate the pain to a specific traumatic event. Athletes who develop patella tendonosis are usually involved in jumping sports, although any sport that requires large forces to be generated through the extensor mechanism of the leg can lead to this disorder. The progression of symptoms can be broken down into phases.

Phase 1) Pain after activity only with no decrease in performance during activity.

Phase 2) Pain during activity also, but the athlete is still able to compete

Phase 3) Pain during activity that precludes satisfactory play

On physical examination, patients have localized tenderness over the patellar tendon that is usually at the inferior border of the patella. This can be assessed most easily with the knee in full extension, where pressure on the proximal pole of the patella lifts the distal pole to make it more accessible to palpation. Patients may have patella alta (high patella) which can cause increased forces to be transmitted to the patellar tendon. Another commonly associated finding is patellar malalignment and patellar laxity. Tracking of the patella should therefore be assessed, along with its commonly associated findings of vastus medialis obliquus weakness, lateral tilting, apprehension sign, etc. Many researchers have also associated muscle tightness with this problem, so flexibility in the quads, hamstrings and gastrocs should be assessed.

Jumper's Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Sports Medicine, Figure 2

Diagnostic Imaging

Standard x-rays are valuable in showing associated malalignment of the patella and presence of patella alta. Also, sometimes degeneration or cyst formation can be seen in the inferior pole of the patella. However, x-rays are not necessary to make the diagnosis.

Ultrasound has also proven valuable in showing areas of degenerated tendon, but it has largely been replaced by MRI

MRI scanning (left) is the most valuable tool in delineating the extent of degeneration and precisely localizing the areas of focal degeneration.  MRI scanning should be reserved for the resistant case, cases of equivocal diagnosis or as a pre-operative tool.

Treatment

Most cases of patellar tendinitis are treated non-surgically. In the early phases, ice, rest and non-steroidal medications are the mainstays of treatment. However, when the tendon begins to heal, usually after 3 or 4 days of rest, it will repair itself based on the stresses imposed on the tendon. Therefore, most surgeons will not recommend prolonged periods of rest. Instead, gentle exercises are usually begun early to help the tendon heal.

Rehabilitation is the mainstay of treatment for patellar tendinitis. As noted above, many patients with tendinitis have tight muscles. Strengthening exercises for the quads, hamstrings and ankle musculature can prove curative. If patellar tracking problems exist, strengthening exercises that promote proper tracking are begun. Recent research has pointed to weakness in the ankle dorsiflexors as contributing to this problem, so the rehab program must include exercises to strengthen these muscles.

Jumper's Knee, Dr. Allen F. Anderson, Nashville, Orthopaedic Sports Medicine, Figure 3

Along with the rehab program, therapeutic modalities are begun including massage, ultrasound therapy, iontophoresis, phonophoresis, heat etc. It should be noted that these provide symptomatic relief only and do nothing to address the underlying problem.

Many trainers and surgeons use infrapatellar straps to provide symptomatic relief. This is simply a band of elastic material that wraps around the knee, compressing the patellar tendon. This will theoretically alter the mechanical forces across the tendon and provide relief.

Many athletes are unable to tolerate infrapatellar straps during sporting activities, saying the pain caused by the strap across the back of the knee is worse than the original problem. Most find that taping the patella (McConnel taping) provides more relief and is more comfortable during activities.

Steroid injections into the patellar tendon should be avoided. Cortisone weakens tendinous tissue and can lead to patellar tendon rupture. Patients with very resistant cases in which a steroid injection is considered, must be counseled about the possible complications. Also, injections should be followed by a prolonged period of rest from sports, to allow the tendon to heal, although this does not insure a rupture will not occur.

In those patients with resistant symptoms, who fail to improve with a lengthy rehab protocol, surgery may be the only option. Surgery usually involves removal of degenerated tissue and some form of procedure to stimulate healing. Procedures include debridement of the degenerated tendon, making multiple drill holes in the distal pole of the patella to stimulate a healing response, excising a portion of the inferior pole of the patella and finally, making multiple longitudinal cuts in the tendon. The results of these surgical procedures are generally good although patients should be informed that there is no guarantee of success. Many surgeons will perform arthroscopy at the same time to assess patellar tracking problems and impingement of the fat pad, which can mimic this disorder. If tracking problems are seen, corrective action, such as a lateral release, may be undertaken to help healing.

Return to Sports

When athletes have eliminated the causative problems such as inflexibility and have regained strength, a gradual return to sports is permitted as symptoms allow.

 
© Allen F. Anderson, M.D. 2017