September 01, 2009
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Tibial spine injuries in children similar to adult ACL injuries

One study, looking at X-ray and MRI results, has found little or no difference between the injuries.

Though some have suggested that the biomechanics of tibial spine injuries that occur frequently in children are somehow different from an adult ACL injury, a recent study has found that the differences are negligible.

In a presentation by Kevin G. Shea, MD, to colleagues at the American Academy of Orthopaedic Surgeons annual meeting, MRI studies were revealed to have provided insight into the mechanism of the injuries.

Injury patterns

“The purpose of this study was to describe MRI findings and associated bone contusion frequency in tibial spine avulsion injuries to determine if the injury patterns were similar to those seen in adult knees,” Shea said.

“We tend to see these bone contusions in at least 70% — and some say as much as 90% — of acute ACL tears,” he added.

Shea and associates reviewed the X-rays and MRIs of 16 tibial spine avulsion injuries in patients ranging from 7 to 15 years old. All of the patients were skeletally immature; four were girls, 12 were boys. Their injuries were classified by the Myers McKeever classification scale, enabling the fracture type to be qualitatively determined.

The MRI findings for other injuries such as contusions and injuries to the ligaments or meniscus were also recorded in addition to the locations of bone contusion patterns.

Nondisplaced tibial spine avulsion

Bone contusion in the lateral compartment

MRI images showing nondisplaced tibial spine avulsion and bone contusion in the lateral compartment.

Images: Shea KG

Surprising results

As classified by the modified Myers McKeever system, the distribution of fracture types was: four type I; three type II; and nine type III. Eighty-eight percent of the patients investigated were found to have bone contusions and 69% of the bone contusion patterns were located in the medial femoral condyle — 75% in the lateral femoral condyle, 81% in the lateral tibial plateau and 31% in the medial tibial plateau.

According to the results of the study, meniscus tears were present in 44% of the patients. Meniscus tears were identified in two of the four type I fractures.

These findings go against that of the existing literature, as the incidence of meniscus injury was significantly higher than what had previously been reported. Furthermore, meniscus tears being found in type I injuries suggests that these injuries — frequently seen as ‘benign’ — may need to be evaluated with MRI, according to Shea. MRI evaluation of meniscus tears have a high false positive rate in children, these need to be considered in this evaluation.

Similar mechanism of injury

The results of the study point toward the bone contusion patterns seen in the lateral compartment being similar to those seen in adult ACL tear patients, suggesting a similar mechanism of injury for ACL tears and tibial spine avulsions.

“I think the patterns of the bone contusions that we saw are very similar to that which you see in adults,” he said.

For more information:
  • Kevin G. Shea, MD, is co-director of the Intermountain Orthopaedics Sportsmedicine Program. He can be reached at Intermountain Orthopaedics, 600 Robbins Road, #401 Boise, ID 83702; 208-383-0201; e-mail: kgshea@aol.com. He has no financial interest in any products or procedures mentioned in this article.

Reference:

  • Shea, KG, Grimm N, Laor T, et al. MRI findings in tibial spine injuries: a look at bone contusion patterns. Paper #598. Presented at the American Academy of Orthopaedic Surgeons 76th Annual Meeting. Feb. 25-28, 2009. Las Vegas.