Knee Pain
Knee pain is a common complaint that is readily evaluated by focusing on the anatomic structures. A focused history and exam will often give the diagnosis. Because hip pain can radiate to the knee, a thorough lower extremity exam should always be performed.
Differential Diagnosis
- Septic arthritis
–Characterized by redness, swelling or effusion, warmth, pain with active and passive ROM, fever or chills
–Requires urgent evaluation and diagnosis
- Osgood-Schlatter disease (OSD)
–Repetitive microtrauma to the bone-tendon junction where patellar tendon inserts into the secondary ossification center of the tibial tubercle
–Onset at early adolescence, more often in athletes
- Sinding-Larsen-Johansson disease
–Similar to OSD, except localized to distal pole of the patella
- Meniscal pathology
–Meniscal tears are usually associated with acute trauma, and involve pain and swelling with mechanical symptoms such as popping, clicking, or locking
–Discoid meniscus: Mechanical symptoms and plain X-rays show squaring, widening, and cupping
- Ligamentous injury
–Medial collateral ligament sprain via overuse injury or valgus force to knee
–Anterior cruciate ligament tear associated with sport noncontact pivoting injury, associated with a “pop” and immediate swelling
–Posterior cruciate tear associated with direct trauma to anterior tibia or hyperflexion with plantar flexed foot
–Lateral collateral ligament injury is rare
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Osteochondritis dissecans
–Trauma resulting in separation of subchondral bone and cartilage at lateral aspect of medial femoral condyle
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Patellar subluxation/dislocation
–Lateral displacement of patella associated with increased Q angle, genu valgum, and femoral anteversion (more common in women)
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Bursitis
–Chronic friction over pes anserine, iliotibial band, or capsular bursa leads to inflammation and thickening of the bursa
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Bipartite patella
–Common variant of patellar ossification
Workup and Diagnosis
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History
–Specific location, duration, onset, aggravating or alleviating factors, and pain characteristics
–Previous trauma, preceding illness, or associated symptoms
–Past medical history and family history including bone, hematologic, or metabolic disorders
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Physical exam
–Bilateral hip, knee, and ankle exam
–Redness, warmth, effusion, active and passive ROM
–Palpate joint line, patella, tibial tubercle, pes anserine,
and medial/lateral ligaments
–Patella tracking or apprehension, varus/valgus stress, Lachman, and anterior posterior drawer tests
–Crepitus along the flexion arc and McMurray test
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Labs
–Often not needed unless concerned about infection
–CBC with differential, platelets, PT/INR, ESR, CRP
–Knee aspirate for cell count and differential with Gram stain, culture, and crystals
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Radiography
–Plain X-ray: Screening knee films include AP, lateral, Merchant views
–AP pelvis and frog-leg lateral of the pelvis or femur films if indicated by exam findings
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MRI to show soft tissues such as meniscus and ligaments
–May demonstate joint effusion in synovitis/infection, marrow edema in osteomyelitis, ligament rupture
Treatment
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Septic arthritis requires immediate surgical intervention and, unlike hip sepsis, the knee may be easily ruled out by aspiration in either emergency room or clinic
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Generally rest, ice, NSAID therapy, and short course of physical therapy to improve strength is the treatment of choice for many of the more common ailments, including bipartite patella, bursitis, patella subluxation, small osteochondritis dissecans lesions, ligament sprain, Osgood-Schlatter and Sinding-Larsen-Johanssen disorders
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Knee immobilization is warranted in acute injuries and non-weight bearing when fracture or ligament injury is suspected, to allow time for diagnostic evaluation to be performed while keeping the patient comfortable and protected from further injury
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Knee arthroscopy is minimally invasive and helpful with diagnosis or treatment in case of ligament repair, Osteochondritis dissecans repair and realignment procedures
Book Source Details
- Book Title: In A Page: Pediatric Signs and Symptoms
- Author(s): Jonathan E. Teitelbaum, Kathleen O. Deantonis, Scott Kahan
- Year of Publication: 2007
- Copyright Details: In A Page: Pediatric Signs and Symptoms, Copyright © 2007 Lippincott Williams & Wilkins.
Other Book Chapters Related to Pain
Read excerpts from these other book chapters related to Pain:
Copyright Details: In A Page: Pediatric Signs and Symptoms, Copyright © 2008 Williams & Wilkins.
More About Causes of Pain
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More About This Book:
Title: In A Page: Pediatric Signs and Symptoms
Authors: Jonathan E. Teitelbaum, Kathleen O. Deantonis, Scott Kahan
Publisher: Lippincott Williams & Wilkins
Copyright: 2007
ISBN: 1-4051-0427-9
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» Next page: Scrotal Pain (In A Page: Pediatric Signs and Symptoms)
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