Pediatric orthopedic cases 36

CASE                               36                               

 

A 12-year-old boy is brought to your clinic for evaluation after being seen in the ER yesterday due to a twisting injury to his left leg from a bike fall. He had intense pain in the knee which started to swell almost immediately. On examination, you note that he has an effusion and is holding the leg in about 10 degrees of flexion. He is very guarded on examination, making ligamentous testing unreliable. You order knee x-rays to further assess (Figs. 10–58 and 10–59).

 

 

 

Figure 10–58

 

 

Figure 10–59

 

Based on the x-rays, you explain to the family that the patient has the following:

1. ACL tear

2. Tibial tubercle fracture

3. Tibial eminence fracture

4. Osteochondral defect

5. A transient patella dislocation

 

Discussion

The correct answer is (C). The patient has a tibial eminence fracture. On the AP view, there is an irregularity of the tibial spine that can be seen, but the lateral view is the view that best shows this injury. You can clearly see that the tibial spine is displaced on this view. The Meyers and McKeever classification is what is used to describe tibial eminence fractures—type 1 injury is a minimally displaced fracture of the tibial eminence. A type 2 tibial eminence fracture is lifted anteriorly, but has an intact posterior hinge. In a type 3 fracture, the fracture fragment is completely displaced.

You explain to the family that the fracture is displaced and you would like to get

additional information before making a recommendation as to how to proceed. You order the following:

1. Ultrasound of the knee

2. Bone scan and MRI

3. Ultrasound and MRI

4. CT and MRI

5. CT and ultrasound

 

Discussion

The correct answer is (D). A CT scan is useful in visualizing the details of the fracture pattern, the shape, size, and position of the tibial spine. The MRI is very important because in nearly 40% of patients there are associated injuries such as meniscus, capsule, collateral ligament injuries, or an osteochondral fracture. Ultrasounds and bone scans are not utilized in the evaluation of tibial spine fractures. Some surgeons who have access to high-resolution MRI are no longer obtaining CT scans (or doing so much more selectively) because the high-resolution MRI is providing sufficient information about the bony anatomy as well as the soft tissue involvement and the radiation associated with a CT scan can be avoided.

The advanced imaging studies show a completely displaced tibial eminence fracture, and you recommend surgery. You explain that your preferred surgical technique is an arthroscopic approach, but an open arthrotomy would also be acceptable (no studies yet show one to be superior to the other you explain, but your personal preference is arthroscopic repair). At the time of surgery, you find that there is soft tissue blocking the reduction. What anatomic structure is most likely to be blocking the reduction?

1. Anterior horn of lateral meniscus

2. Posterior horn of medial meniscus

3. Anterior horn of medial meniscus

4. Intermeniscal ligament

5. Plica

 

Discussion

The correct answer is (A). Kocher found that there was soft tissue entrapment in 26% of type 2 fractures and 65% of type 3 fractures. In cases where there was soft tissue entrapment, the anterior horn of the medial meniscus was the most likely

culprit, followed by intermeniscal ligament and rarely the anterior horn of the lateral meniscus. The posterior horn of medial meniscus and plicas are not in an anatomic location to affect the tibial spine reduction.

Surgery goes well and you are confident with your surgical fixation of the tibial eminence fracture. You explain to the family that after an initial brief period of rest and limited ROM, you would like to start range of motion exercises. If ROM is started more than 4 weeks after surgery, the child is at risk of what?

1. Arthrofibrosis

2. Nonunion

3. ACL laxity

4. No risk—waiting more than 4 weeks to begin ROM is your plan

 

Discussion

The correct answer is (A). Patel et al. showed, in a retrospective review of 40 patients, that patients who didn’t start range of motion exercises until more than 4 weeks after surgery were 12 times more likely to develop arthrofibrosis. Nonunion is very rare—especially in patients who had surgery. ACL laxity is a known finding after tibial eminence fractures. A study by Willis showed that as many as 74% of patients had ACL laxity on KT-1,000 testing when compared to the uninjured side, but this was not clinically relevant in the majority of patients. Laxity is more common in those treated nonsurgically than in surgical patients. D is not correct since there has been increased risk of arthrofibrosis shown in patients who do not begin ROM until more than 4 weeks after surgery.

 

Objectives: Did you learn...?

 

The classification of tibial eminence fractures?

 

 

 

The diagnostic imaging evaluation of tibial eminence fractures? Nonsurgical and surgical options for tibial eminence fractures? Blocks to reduction?

 

Outcomes and anticipated complications?