Medial Tibial Periprosthetic Bone Resorption and Its Effect on Clinical Outcomes After Total Knee Arthroplasty: Cobalt-Chromium vs Titanium Implants.

BACKGROUND

Recently, concerns arose over the medial tibial bone resorption of a novel cobalt-chromium implant. This study aimed at investigating the effects of tibial component material, design, and patient factors on periprosthetic bone resorption and at determining its association with clinical outcomes after total knee arthroplasty (TKA).

METHODS

A total of 462 primary TKAs using 5 types of implants were included. To evaluate tibial periprosthetic bone resorption, we assessed radiolucent lines and change in bone mineral density at the medial tibial condyle (BMDMT). Factors related to bone resorption were assessed using regression analysis. Clinical outcomes were also evaluated with respect to periprosthetic bone resorption.

RESULTS

Compared to titanium implants, cobalt-chromium implants showed a higher incidence of complete radiolucent lines (23.1% vs 7.9% at 2 years post-TKA) and a greater degree of BMDMT reduction. However, there was no significant difference between the implants made of the same material. Increased medial tibial bone resorption was associated with male sex, osteoporosis, larger preoperative varus deformity, longer follow-up period, and lower body mass index. The periprosthetic bone resorption was not associated with clinical outcomes including changes in range of motion and Western Ontario and McMaster Universities Osteoarthritis Index score. Furthermore, no cases warranted additional surgery.

CONCLUSION

Periprosthetic bone resorption was associated with implant material but not with implant design. Moreover, patient factors were related to the medial tibial bone resorption post-TKA. However, the periprosthetic bone resorption was not associated with short-term clinical outcomes. We contend that researchers should incorporate integrative considerations when developing and assessing novel implants.