Ceramic-on-Ceramic (CoC) Total Hip Replacement

Overview

Material Properties

• Very high surface hardness - more scratch-resistant than metal
• Surface finish smoother than metal implants due to high density
• Highest Young's modulus (stiffest implant material) compared to cobalt-chrome, titanium, and zirconia-reinforced alumina
• Biologically inert debris - no ionization, no cancer risk, no dysplastic/metaplastic effects on local soft tissues

• Campbell's Operative Orthopaedics 15th Ed 2026, p. 247

Generations of Ceramic Implants

• Flawed implant design with very thick neck required for strength
• Thick neck adversely reduced the head-neck ratio
• Poor manufacturing technique, low ceramic density, coarse microstructure
• High fracture rates, inadequate fixation, occasional rapid wear with osteolysis

• Hot isostatic pressing (HIP) manufacturing technique
• High ceramic density, finer microstructure
• Skirt elimination - better head-neck ratio
• Substantially lower fracture rate

• Fracture rate approximately 1 in 100,000 (0.001%) vs. 1 in 5,000 (0.02%) with pure alumina
• Excellent wear properties and increased fracture toughness
• Miller's Review of Orthopaedics 9th Ed, p. 447

FIG. 5.41 - Retrieved first-generation CoC THA. Note the thick neck (required for strength) which reduced head-neck ratio, and acetabular fracture resulting from neck impingement. - Miller's Review of Orthopaedics 9th Ed

Advantages

• Campbell's Operative Orthopaedics 15th Ed 2026, p. 246-247
• Bailey & Love's Short Practice of Surgery 28th Ed, p. (Table 39.6)

Disadvantages

1. Hip Squeaking

• Reported incidence: up to 10% of CoC bearings, though generally lower in most series
• Onset typically >1 year after implantation
• Psychologically distressing; may require revision

• Implant malpositioning
• Lever-range wear (microseparation during swing phase of gait)
• Stripe wear - arcuate area of roughness on head/cup from repetitive subclinical subluxation at extremes of motion (e.g., rising from a chair)
• Disrupted lubrication
• Implant resonance - vibrational resonance amplified by the prosthetic construct into the audible range

2. Fracture

• Historically a major concern due to ceramic's low toughness
• More common with smaller head sizes (28 mm) and shorter neck lengths
• Modern alumina matrix composite: fracture rate ~0.001% (very low)
• Fracture treatment: Replace with another CoC bearing - because microscopic ceramic shards remain after fracture and are severely abrasive; placing a traditional PE bearing risks rapid PE wear (highly cross-linked PE is preferred if PE bearing used after ceramic fracture)

3. Head Size Limitation

• Ceramic socket must sit within a metal acetabular shell, and must have minimum thickness to resist fracture
• This limits the ultimate head size achievable
• Stability is less than large-diameter MoM bearings
• Fluid film lubrication is less optimal with smaller head radii

4. Head Length / Offset Limitation

• No skirted heads available - limited neck length options
• Can limit hip offset, predisposing to hip impingement and instability
• Careful preoperative templating required

5. Component Constraints

• Lipped and offset liners are unavailable
• Locking mechanism not universally compatible between manufacturers
• Chipping on implantation reported - careful assembly required to ensure insert is properly oriented before impaction

6. Cost

• Significantly more expensive to manufacture than polyethylene bearings

7. Stripe Wear / Edge Loading

• CoC is more sensitive to implant malposition than other bearings
• Excessively vertical cup orientation leads to greater ceramic wear and edge loading
• More demanding surgical technique required

Surgical Considerations

• Ceramic insert mates with metal shell via taper junction
• Some manufacturers use metal backing to protect the insert rim from impingement
• Special care during insertion - the insert must be correctly oriented before impaction

• Limited range of neck lengths available
• No skirted heads
• If placing a new ceramic head on a previously used femoral neck (revision): must use a ceramic head fitted with an internal titanium adapter sleeve - a roughened/corroded trunnion can cause burst fracture of a bare ceramic head

• Campbell's Operative Orthopaedics 15th Ed 2026, p. 247

Oxidized Zirconium (Ceramicized Metal) - Related Material

Indications / Patient Selection

• Young, active patients - where long-term wear performance justifies cost and specific complication profile
• Patients in whom osteolysis from PE wear is a dominant concern
• Patients without metal hypersensitivity who need hard-on-hard bearing for wear reduction

Recent Evidence (2024-2026)