Hiroshi Ito, Toshiki Nakamura, Tatsuya Sato, Yasuhiro Nishida, Hiromasa Tanino and Masaru Higa
Background: It has been reported that the function of the labrum is to ensure that an increased surface area encountered the femoral head and spares the cartilage from excessive strain. The purpose of this study was to determine whether early deformation of the hip articular cartilage occurs under high-load conditions in the presence/absence of the labrum.
Methods: The hip joints of 4 beagle dogs were retrieved. A continuous static load of 80 Kg was applied for 2.5 hours. Magnetic resonance imaging (MRI) was performed immediately after the loading and at 30, 60, 90, 120, and 150 minutes after the loading. The load was then removed, and the specimens were stored for 14 h to allow the cartilage to recover. The labrum was then carefully removed, and the experiment was performed again.
Results: The maximum percentage change in cartilage thickness was 35.3 ± 17.4% when the labrum was intact and 55.7± 7.5% after the labrum had been excised (p=0.060). Labral excision resulted in a reduction in cartilage thickness. Cartilage thickness was significantly decreased in the normal and labral excision models immediately after loading (p=0.003 and p=0.022, respectively).
Conclusion: The labrum plays a role in dispersing loads equally across the joint cartilage and reduces the load placed on the maximum weight-bearing region of cartilage. Early articular cartilage deformation occurred under high-load conditions both before and after the excision of the labrum.