Tibial component with and without stem extension in a trabecular metal cone construct

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Materials Science

Background:

• Trabecular metal cones are used to reconstruct major bone defects in total knee arthroplasty.
• The necessity of stem extension for tibial components after trabecular metal cone reconstruction remains unclear.
• Stem implantation can enhance stability but may carry potential negative side effects.

Purpose of the Study:

• To evaluate the stability and strain distribution of tibial plateau reconstructions using trabecular metal cones with and without stem extension.
• To determine if prosthetic stability is influenced by bone mineral density.
• To compare biomechanical outcomes of stemmed versus non-stemmed tibial components in this context.

Main Methods:

• Seven pairs of cadaveric tibiae underwent tibial revision arthroplasty for 2B bone defects, with one tibia per pair receiving a stemmed component and the other a non-stemmed component.
• Specimens were subjected to one bodyweight load, alternating between medial and lateral tibial components.
• Implant-bone micro-motions, bone strains, and bone mineral density were measured and analyzed.

Main Results:

• No significant difference in strain distribution was observed between stemmed and non-stemmed components.
• Non-stemmed components exhibited a slight, clinically insignificant increase in varus tilt (0.14°).
• Bone mineral density significantly correlated with anterior/posterior tilt (ρ: -0.72).

Conclusions:

• Tibial components implanted with or without a stem after trabecular metal cone reconstruction yield comparable biomechanical conditions regarding stability and strain distribution.
• The findings suggest that stem extension may not be mandatory in these cases.
• Further in vivo studies are recommended to confirm these biomechanical observations and guide clinical decision-making.