The influence of radiologic bone transparency after hybrid total knee arthroplasty on clinical outcomes: Minimum 6-year follow up of 214 cases

Abstract

Background: This study aimed to investigate how bone transparency affects loosening of the cementless femoral component by serially analyzing radiologic images in hybrid total knee arthroplasty (TKA).

Methods: A total of 214 cases of TKA performed using the hybrid technique that were followed up for at least 6 years were retrospectively investigated. Bone transparency around the femoral component during the follow up period was evaluated. All TKA cases were divided into two groups and compared: those with radiologic bone transparency (bone transparency group, n = 51) and those without radiologic bone transparency (no bone transparency group, n = 163).

Results: The incidence of revision TKA in all patients was 6.1%, and obesity, preoperative and postoperative mechanical alignment did not affect surgical outcomes. All bone transparency cases were asymptomatic, and only 8/51 cases (15.7%) of bone transparency spontaneously resolved. Between the bone transparency and no bone transparency groups, there was no difference found in the preoperative and postoperative radiologic parameters and clinical outcomes. During the follow up period, there were four (1.9%) cases with a definite radiolucent line in the femoral component, all of which belonged to the bone transparency group.

Conclusions: The bone transparency around the femoral component that appears on radiography after hybrid TKA could be an early sign of aseptic loosening; therefore, follow up serial radiography is essential.