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
course.
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
activity.
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.
References:
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.
362,363.
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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