Describe the clinical relevance of cement viscosity in cemented arthroplasty and its effect on cement interdigitation.

• A. Higher viscosity yields a thicker mantle with less penetration
• B. Lower viscosity improves interdigitation but may risk cement mantle defects
• C. The optimal viscosity balances fixation and mantle integrity
• D. All of the above

Answer: (D)

The key idea is how cement viscosity controls flow and how deeply it penetrates bone to achieve fixation. When cement is high in viscosity, it flows less and tends to form a thicker surrounding mantle around the implant, but penetrates less into the cancellous bone, reducing interdigitation. Lower viscosity allows the cement to flow into bone porosity more readily, improving interdigitation and fixation, but it can also lead to over-penetration or irregularities in the cement mantle, risking mantle defects. The clinically effective approach is to use a viscosity that provides sufficient interdigitation for stable fixation while maintaining a solid, uniform cement mantle. Since these effects all describe real trade-offs and together point to balancing fixation with mantle integrity, the best answer accounts for all of them.