Meniscal translocation and deformation throughout the range of motion of the equine stifle joint: an in vitro cadaveric study.

This study investigates the translocation and deformation of equine menisci—a type of cartilage in the knee—in stifle joint motion to gain understanding about potential injury risk factors to the cranial horn of the medial meniscus in horses. The research used radiographic markers, magnetic resonance imaging and motion evaluations to examine the behavior of the menisci in cadaver specimens.

Study Methodology

• The study examined meniscal translocation and deformation in the stifle joint across a full range of equine motion. This was done using six cadaver specimens where the researchers embedded radiographic markers in the periphery of the menisci.
• To detect any variation in translocation between the medial and lateral menisci, the researchers captured proximal-distal radiographs at 15-degree intervals. The test range was from full flexion (30 degrees) to full extension (160 degrees).
• To further enhance the study, MR images of three additional cadaver stifles were captured in axial and sagittal planes at pre-determined stifle angles.

Study Results

• The research found out that the lateral meniscus recorded a significantly higher mean cranial-caudal translocation (1.6 times) from full extension to full flexion, in comparison to the medial meniscus.
• The cranial horn of the medial meniscus was the least mobile of the four meniscus horns. However, it recorded a significant cranial displacement relative to the cranial horn of the lateral meniscus in the terminal 10 degrees of extension.
• MRI images showed a considerably higher axial compressive strain in the cranial horn of the medial meniscus compared to the cranial horn of the lateral meniscus in the terminal 10 degrees of extension.

Study Conclusion

• The study concluded that the equine menisci exhibit cranial-caudal translocation over the tibia within the full range of the stifle joint movement.
• The cranial horn of the medial meniscus, even though it’s the least mobile of the four meniscal horns, undergoes significant cranial translocation and axial compression in the final 10 degrees of extension.
• Hyperextension of the stifle may place the cranial horn of the medial meniscus at risk of injury, potentially explaining the higher prevalence of meniscal tears at this location.