Acute Knee Pain Following Trauma
Radiology Cases in Pediatric Emergency Medicine
Volume 4, Case 11
Loren G. Yamamoto, MD, MPH
Kapiolani Medical Center For Women And Children
University of Hawaii John A. Burns School of Medicine
     This is a 16-year old male who injured himself 
playing basketball.  He was running backward when he 
tripped and fell directly onto his right knee with 
immediate severe pain.  He was unable to ambulate.  
His past medical history is unremarkable.
     Exam:  VS T37.0 (oral), P88, R18, BP 130/50.  He is 
alert.  He is uncomfortable but not in acute distress.  He 
is of average height and weight for his age.  His right 
knee shows obvious swelling over his pre-patellar 
region.  His patella is non-tender, but pushing on the 
patella results in some tenderness over his upper 
anterior tibia just below the patella.  There is tenderness 
over the upper anterior tibia.  There is no instability 
about the knee.  The drawer sign is negative.  His 
patella is not dislocated.  There is no tenderness over 
his femur.  There is no tenderness over his mid and 
distal tibia.  His fibula is non-tender.  There are no 
deformities.  His pulses and sensation are intact 
distally.  He is unable or unwilling to bear weight on his 
right leg.  He says he can't move his knee on his own 
very well.
     He is given some analgesics.  Radiographs of his 
right knee are obtained.

View knee radiographs.

     Clinically, he does not seem to have a patella 
fracture so a sunrise view of the knee is not obtained.  
His problem appears to be more distal, in the upper 
tibia.  The AP view shows no abnormalities of the distal 
femur.  The tibial plateau and the metaphysis appear to 
be normal.  However, there is a bony fragment to the 
left of the image superimposed over the joint space.
     The lateral view is more revealing in that it shows 
this bony fragment clearly resulting from an avulsion of 
the tibial tuberosity.  The patellar tendon is not visible of 
     His knee is immobilized and he is placed on 
crutches.  Orthopedic follow-up is arranged.
     Osgood-Schlatter's disease results from repeated 
stress of the tibial tuberosity apophysis.  It usually 
occurs in adolescents who  jump a lot (basketball 
players and volleyball players).  Repeated pulling on the 
quadriceps and patellar tendon at the insertion of the 
tibial tuberosity results in microfracture or stress 
fracture (apophysitis).  This manifests as pain and 
tenderness over the tibial tuberosity during athletic 
     In a more extreme injury, the tibial apophysis is at 
risk for avulsion.  It may rupture fully or partially 
resulting from a forced flexion when the quadriceps is 
contracted, by extreme contraction, or from direct 
trauma (i.e., falling onto the tibial tuberosity).  The 
typical history is that of sudden buckling of the knee 
with extreme pain.  The pain subsides to some degree.  
If the patella is inferior to its usual position, this 
suggests a proximal rupture of the quadriceps tendon.  
If the patella is superior to its usual position, this 
suggests a patellar tendon rupture at the tibial 
tuberosity.  Interestingly, the patient may be able to 
weakly flex and extend the knee despite the tendon 
rupture, but will not be able to hold up their lower leg 
against gravity.
     Also of interest is that many of these injuries are 
missed on initial evaluation.  Such patients may present 
with an old tendon disruption with complaints of knee 
buckling and inability to climb stairs.  Patients with 
patellar tendon ruptures should be immobilized.  Partial 
tendon ruptures can be treated conservatively with 
immobilization and casting.  More severe tendon 
ruptures require early surgical repair.

     Harder JA.  Fractures and dislocations of the 
proximal tibia and fibula.  In:  Letts RM (ed).  
Management of Pediatric Fractures.  New York, 
Churchill Livingston, 1993, pp. 625-626.
     The knee.  In:  Simon RR, Koenigsknecht (eds).  
Emergency Orthopedics, The Extremities, second 
edition.  Norwalk, CT, Appleton & Lange, 1987, pp. 
     Bachman D, Santora S.  Orthopedic trauma.  In:  
Fleisher GR, Ludwig S (eds).  Textbook of Pediatric 
Emergency Medicine, third edition.  Baltimore, William 
& Wilkins, 1993, pp. 1273-1274.

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Web Page Author:
Loren Yamamoto, MD, MPH
Associate Professor of Pediatrics
University of Hawaii John A. Burns School of Medicine