Fresh Meniscus Degradative and Extracellular Matrix Responses Mirror Acetabular Labral Responses Under Tensile Strain...

To compare clinically relevant cellular responses from acetabular labrum, tendon, and knee meniscus to biaxial tensile loading in culture.

Human acetabular labrum (LAB), quadriceps tendon (TEN), and knee menisci (MEN) cultured cells were subjected to mechanical stimulation with a biaxial sinusoidal waveform with three different elongation strains for 5 days using the Flexcell FX-4000T strain system. Concentrations of prostaglandin E₂ (PGE2), matrix metalloproteinase (MMP)-1, MMP-2, MMP-3, MMP-9, MMP-13, interleukin (IL)-6, IL-8, IL-1β, monocyte chemoattractant protein (MCP)-1, and growth regulated protein (GRO)-α and proteoglycans (GAG) were then measured. Statistical analysis was performed to detect differences in media biomarker concentrations among load groups within each cell type and among cell types within each load group.

TEN produced higher concentrations of MMP-3 than LAB at 0% (P < .001, 95% confidence interval [CI] [45,656.46, 191,119.273]), 4% (P = .012, 95% CI [11,753.043, 157,215.857]), and 10% (P = .016, 95% CI [9463.91, 154,926.723]) strain levels. LAB produced lower concentrations of IL-8 compared with MEN (P = .003, 95% CI [-152.318, -20.275]) and TEN (P = .011, 95% CI [-143.375, -11.332]) cells at 0% strain. At 0% strain, MEN produced higher concentrations of PGE2 compared with LAB (P < .001, 95% CI [36.369, 102.511]) and TEN (P < .001, 95% CI [23.002, 89.145]). The production of MCP-1 for TEN tenocytes in the 0% strain group was higher than TEN tenocytes in the 4% (P = .03, 95% CI [48.614, 1608.22]) and 10% (P = .003, 95% CI [233.124, 1792.73]) strain groups.

Meniscofibrochondrocyte responses more closely resembled those from labrum cells; however, MEN inflammatory biomarker levels were significantly higher than LAB at all strain levels. The absence of strain was associated with significant inflammatory and degradative cellular responses in both labral graft types.

The results of this study provide further support for use of fresh meniscus allografts for acetabular labrum reconstruction and highlight potential advantages over tendon grafts based on cellular responses to load in comparison to native acetabular labrum.