Chemical Vapour Deposition:

• A skeleton (scaffold) of Reticulated Vitreous Carbon is placed in a vacuum chamber.
• Tantalum gas is deposited onto the skeleton.
• Result: 99% Pure Tantalum surface with a carbon core.

Structure:

• Cellular: Resembles trabecular bone (dodecahedron shape).
• Porosity: 75-80% (Standard sintered beads are only ~30-40% porous).
• Pore Size: 400-600 microns (Ideal for osteoblast ingrowth).

1. Acetabular Revision:

   • "Paprosky" defects.
   • Tantalum Cones/Wedges fill large bone voids.
   • Trabecular Metal cups bridge defects with minimal screws due to high friction.

2. Knee Revision:

   • Metaphyseal Cones (Femur and Tibia).
   • Provide structural support where cancellous bone is lost.

3. Spine:

   • Cages (interbody fusion).
   • Bioactive surface + Radiolucent properties (sort of - less artifact than steel).

Young's Modulus Comparison:

• Cortical bone: 15-20 GPa
• Cancellous bone: 0.1-2 GPa
• Tantalum: 3 GPa ✓ Closest match to cancellous bone
• Titanium alloy: 110 GPa (excessive stiffness)
• Stainless steel: 200 GPa (severe stress shielding)

Clinical Significance:

• Minimizes stress shielding
• Promotes physiological load transfer
• Stimulates bone remodeling
• Reduces risk of peri-implant bone loss

1. Bobyn JD, et al. Characteristics of bone ingrowth and interface mechanics of a new porous tantalum biomaterial. JBJS Br. 1999.
2. Sporer SM, Paprosky WG. The use of a trabecular metal acetabular component for the treatment of severe acetabular defects. J Arthroplasty. 2006.

Cost:

• Significantly more expensive than traditional implants
• 3-5 times the cost of standard titanium components
• Economic consideration in public hospital systems

Removal Difficulty:

• Extensive bone ingrowth makes revision extremely challenging
• May require extended trochanteric osteotomy or acetabular osteotomy
• Bone loss inevitable during removal
• Consider carefully before use in young patients

Radiopacity:

• More radiopaque than titanium
• Can obscure radiographic assessment of bone-implant interface
• May create artifact on CT imaging (though less than stainless steel)
• MRI compatible but creates some artifact

Not a Panacea:

• Cannot substitute for massive bone loss without structural support
• Still requires reasonable host bone contact
• Pelvic discontinuity may still require additional fixation (plates, THA cage)

Limited Long-term Data:

• Most studies have 5-10 year follow-up
• 20+ year data still emerging
• Uncertain performance in very young patients (less than 40 years old)

Tantalum (Trabecular Metal) products are TGA-approved and widely available in Australia for revision arthroplasty. The use of tantalum implants has increased significantly in Australian orthopaedic practice over the past decade, particularly in tertiary referral centres managing complex revision cases. Data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) demonstrates excellent mid-term survivorship for tantalum components in revision hip and knee arthroplasty, comparable to international outcomes.

In the public hospital system, the high cost of tantalum implants (typically 3-5 times more expensive than standard revision components) requires careful consideration and often needs senior approval or specific funding allocation. Most major metropolitan hospitals have tantalum cones, augments, and cups available on their arthroplasty instrument sets for complex revision cases. However, access may be more limited in regional centres, where patients with severe bone loss may require transfer to tertiary facilities.

From a training perspective, RACS-accredited orthopaedic training programs emphasize understanding the biomaterial properties of tantalum as part of the basic science curriculum. Trainees are expected to know the specific numbers (80% porosity, 3 GPa modulus, 0.98 friction coefficient) and be able to explain why these properties make tantalum superior to traditional porous coatings in revision settings. The decision to use tantalum versus alternative solutions (structural allograft, custom triflange components, or reinforcement cages) is a common exam scenario in both written and viva examinations.