Epidemiology of Chronic Knee Pain1:
- 30-35 million children play organized sports, with many playing a single sport year round
- 1.5% of child athletes are injured each year playing sports, accounting for 2.5 million emergency room visits. Chronic, overuse injuries are more common than acute injuries
- Overuse injuries occur when athletes repeat the same submaximal motions over and over without allowing for adequate recovery
- Knee injuries account for 20-36% of all musculoskeletal injuries in college athletes, and the knee is the second most common joint to be injured in sports
- Three main compartments: medial, lateral, and patellofemoral
- Two main joints: tibiofemoral articulation and patellofemoral articulation
YouTube video by Dr. Randale Sechrest showing animation of knee anatomy
YouTube video by Dr. Chris Centeno on how to read a knee MRI
Knee Physical Exam:
- Pain assessment while gathering the patient’s history should include: onset and duration of knee pain, specific location within the knee joint of the pain and whether it radiates, quality and severity of the pain, and whether any movement aggravates or alleviates the pain
- A complete history should also include:
- What sports the child plays
- How long the child has played each sport,
- How long of an “off-season” the child has each year
- What the child’s training and/or conditioning program has been,
- If the child has had prior injuries from overuse.
- Dr. Dan Smith of the University of Wisconsin demonstrates how to perform a proper knee exam:
Chronic Overuse Knee Injuries:
- Improper technique, poorly fitting equipment, training errors, and muscle weakness or imbalance increase risk for sports-related overuse injuries
- When no obvious trauma or other cause of an acute knee injury is present, the differential for chronic knee pain includes:
- Patellofemoral pain syndrome (running or excessive knee flexion),
- Osgood-Schlatter disorder (boys 10-15, jumping sports),
- Iliotibial band syndrome (excessive hip/knee flexion, running),
- Prepatellar bursitis (prolonged kneeling)
Non-Athletic Causes of Disease:
- Infectious: 60% of patients with untreated Lyme disease experience recurring joint effusions, swelling, and warmth; likely monoarthritis; treat with doxycycline or amoxicillin2
- Malignancy: 14% of AML patients develop migratory polyarthritis due to synovial infiltration by leukemic blasts; treating the underlying leukemic process is necessary for treating the pain3
- Malignancy: Osteosarcoma is most common primary bone tumor affecting children or adolescents (peak age 13-16). Malignancy often presents in the distal femur or proximal tibia with localized pain waxing and waning over several months. Physicial exam may reveal a tender palpable mass that will require biopsy4
Increasing Awareness of Overuse Injuries:
- Physicians, athletic trainers, and other medical professionals are working together to raise awareness about overuse injuries, as many are caused by the increasing prevalence of children playing only one sport. They encourage pediatricians to join the campaign, as educating patients and families is the best way to prevent overuse injuries.
- Many are using social media to reach coaches, parents, and teenagers and to further the campaign to stop overuse injuries. Groups using this approach include the Play Safe Initiative (website: http://www.playsafeinitiative.ca/about.html and Twitter: @_playsafe or #preventinjury) and STOP Sports Injuries (website: http://www.stopsportsinjuries.org/ and Twitter: @SportsSafety).
- Cunill-de Sautu B, Gereige RS. Knee conditions. Pediatrics in Review. 2014; 35(9):359-70.
- Steere AC, Schoen RT, Taylor E. The clinical evolution of Lyme arthritis. Ann Intern Med. 1987; 107(5):725).
- Aviña-Zubieta JA, Galindo-Rodriguez G, Lavalle C. Rheumatic manifestations of hematologic disorders. Curr Opin Rheumatol. 1998;10(1):86.
- Mirabello L, Troisi RJ, Savage SA. Osteosarcoma incidence and survival rates from 1973 to 2004: data from the Surveillance, Epidemiology, and End Results Program. Cancer. 2009;115(7):1531.