OTA 1999 Posters

Evaluation of Soft-Tissue Injuries in High-Energy Tibial Plateau Fractures

Stephan V. Yacoubian, MD; Russell T. Nevins, MD; Julian G. Sallis, MD; Hollis G. Potter, MD; Dean G. Lorich, MD, Albert Einstein College of Medicine, Bronx, NY

Purpose: MRI is more advantageous in bony and soft tissue evaluation in high energy tibial plateau fractures when compared to CT and X-rays.

Methods: Forty-nine (49) consecutive high-energy tibial plateau fractures (pedestrian struck, motor vehicle accidents, jumpers) received x-rays (AP/Lateral/ Obliques) and a CT scan in the emergency room, followed by an MRI prior to the definitive treatment. Three experienced trauma surgeons participated in the three arms of the study by randomly reading X-rays alone, X-rays with the CT, and the MRI alone in a blind and independent fashion. The fractures were classified according to both the AO and the Schatzker classification. After evaluating each radiographic study, the surgeons would state their operative plan. Soft tissue evaluation by MRI was made by an experienced MRI radiologist. In addition, all plain radiographs (AP/Lateral/oblique) were evaluated for maximal depression and lateral displacement of fracture fragment. These values were correlated to soft tissue injuries observed by MRI.

Results: Soft Tissue Injuries: For all fracture patterns, 49% had an acute lateral meniscal tear and 49% had lateral capsular separation; 43% had an avulsion fracture of the ACL footprint; 38% had at least an acute partial ACL intra-substance tear. 14% had an acute medial meniscal tear; 55% had at least a partial medial collateral ligament injury; 11% had PCL foot print avulsions, and 11% had a partial PCL intra-substance tear. In addition, the lateral collateral ligament was damaged in 36% of patients. The popliteal muscle tendon junction was injured in 26%. The popliteal-fibular ligament was involved in 28% of cases, and the popliteus tendon was involved in 36%.

Statistical analysis of these injuries revealed that there is a significant association (P=<.05) between the incidence of acute ACL tears and acute lateral meniscal intra-substance tears.

Joint Depression: For all fracture patterns, there was a statistical correlation between joint depression measured on the plain films and lateral meniscal tears. When joint depression was measured > 4mm, there was a 95% chance of lateral meniscal pathology (64% had lateral meniscal intra-substance tears and 31% had peripheral detachment from the capsule). In Shatzker II alone, joint depression > 4mm yielded a 95% chance of a lateral meniscal pathology (68% had lateral meniscal intra-substance tears, and 27% had peripheral detachment from the capsule).

Lateral Displacement: For all fracture patterns, there was also a statistical correlation between lateral displacement measured on the plain films and lateral meniscal tears. When lateral displacement measured > 8mm, there was a 95% incidence of lateral meniscal pathology (61% had lateral meniscal intra-substance tears, and 34% had peripheral detachment from the capsule). In Shatzker II alone, lateral displacement > 4mm yielded a 95% chance of lateral meniscal pathology (68% had lateral meniscal intra-substance tears, and 27% had peripheral detachment from the capsule).

Discussion: MRI has the distinct advantage over CT and X-rays of providing valuable information regarding soft tissue injuries. We found a statistically significant correlation between acute ACL tears and lateral meniscal intra- substance tears which has never been described before. These results also show a correlation between bony injuries on X-ray and soft tissue injuries diagnosed by MRI, in that measuring joint depression and lateral displacement on plain films may predict lateral meniscal pathology. MRI thus provides a more complete assessment of high-energy tibial plateau fractures and allows for a more accurate classification of the fracture as well as a change in the operative management, as seen in 38% of our cases.