Bearing Surfaces in THR — Metal, Ceramic, Polyethylene

Part of The Joint Replacement Guide — Phase 4: The Operation · Article 22 of 42 · Hip

Key Points

  • The “bearing” is the pair of surfaces that move against each other inside your new hip, and several material combinations are used.
  • Modern highly cross-linked polyethylene, combined with either a ceramic or metal head, is the most commonly used and best-evidenced combination today.
  • Metal-on-metal bearings, once popular, are now rarely used after well-publicised problems in a subset of patients.
  • Your surgeon will choose the combination best suited to your age, activity level and anatomy.

What the Bearing Actually Is

Inside every hip replacement, a femoral head (the “ball”) moves against a liner inside the acetabular cup (the “socket”) with every step you take — this pair of surfaces is called the bearing. The materials chosen for the head and the liner affect how the bearing wears over time, which in turn affects the long-term durability of your implant, so this is a genuinely important decision, though one your surgeon will make with you based on well-established evidence rather than personal preference alone.

Polyethylene

Modern highly cross-linked polyethylene, a significantly improved descendant of the material Charnley pioneered, is the most widely used liner material today. It has excellent wear characteristics and a long, well-documented track record in national registries, and can be paired with either a metal or ceramic femoral head.

Ceramic Heads

Ceramic femoral heads are extremely hard and smooth, producing very low wear rates when paired with a modern polyethylene liner (a combination often called “ceramic-on-poly”), and are frequently favoured in younger, more active patients for this reason. Ceramic-on-ceramic bearings (a ceramic head against a ceramic liner) are also used in some cases, offering very low wear but carrying a small, well-recognised risk of an audible squeak from the joint in a minority of patients, and a rare risk of the ceramic component fracturing — both factors your surgeon will discuss if this combination is being considered for you.

Metal Heads

A metal femoral head paired with a polyethylene liner (“metal-on-poly”) remains a well-established, reliable option, particularly favoured in older, less active patients, and has an excellent long-term track record.

Metal-on-Metal — Why It’s Rarely Used Now

Metal-on-metal bearings, popular in the 2000s for their theoretical wear advantages, were found in a subset of patients — particularly with certain hip resurfacing and large-head implant designs — to release metal particles and ions into the surrounding tissue and bloodstream, occasionally causing local soft tissue reactions requiring further surgery. This led to close monitoring requirements and, ultimately, a substantial move away from metal-on-metal bearings across most of orthopaedic practice. If you have an older metal-on-metal hip replacement, you should continue attending any follow-up monitoring your surgeon has recommended, even if you have no symptoms.

In More Depth

The evolution of bearing surfaces is one of the clearest examples of how national joint registries have directly improved patient safety — the problems associated with certain metal-on-metal designs were identified relatively quickly through registry surveillance and regulatory alerts, allowing affected devices to be withdrawn and follow-up protocols established for patients who already had them implanted. Today’s most commonly implanted bearing combinations — highly cross-linked polyethylene with either a ceramic or metal head — have some of the best long-term registry survivorship data of any combination in the history of hip replacement, reflecting decades of incremental material science improvement since Charnley’s original polyethylene design.

This article is general information and does not replace individual clinical advice.

Sources

  • National Joint Registry — Annual Report, bearing surface survivorship data
  • Medicines and Healthcare products Regulatory Agency (MHRA) — metal-on-metal hip guidance
  • British Hip Society — bearing surface guidance

← Back to the Joint Replacement Guide · Previous: Cemented, Uncemented and Hybrid Fixation in THR · Next: Surgical Approaches in TKR