The effect of altering head length on corrosion using a material loss method

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Tribology

Background:

• Corrosion at taper junctions in total hip arthroplasty (THA) is a growing concern.
• Factors like increased offset and head length may increase tribocorrosion risk.
• The clinical significance of this corrosion remains debated.

Purpose of the Study:

• To investigate the impact of femoral head length on corrosion in metal-on-polyethylene (MOP) THA.
• To quantitatively assess material loss at the head neck taper junction.

Main Methods:

• Analysis of 56 retrieved 28-mm cobalt chromium alloy femoral heads (12/14 taper) from a single manufacturer.
• Quantification of corrosion using a material loss method and coordinate measuring for maximum linear wear depth (MLWD).

Main Results:

• No significant difference in mean MLWD was observed across different head lengths (-3, 0, +4, +8 mm).
• No correlation was found between MLWD and explant duration (minimum 2 years).
• No significant difference in MLWD was noted between high and standard offset stems.

Conclusions:

• Within the constraints of this study (28-mm head, single taper construct, MOP articulation), head length did not correlate with material loss.
• Results contrast with qualitative studies and caution against broad generalization.
• Further investigation is warranted for different taper designs and articulation types.