Five-year clinical and radiographic outcomes of Accolade TMZF and Accolade II stem use

Abstract

PurposeAlthough good mid-term results of the first- and second-generation cementless stems have been reported, no study has compared outcomes between generations. This study aimed to compare the mid-term results of Accolade Ti–12Mo–6Zr–2Fe (TMZF) and Accolade II over a 5-year period. MethodsThis retrospective, single-institution, single-surgeon observational study included patients who underwent primary total hip arthroplasty using the Accolade TMZF (n ​= ​71, group I) or Accolade II (n ​= ​73, group II) between January 2009 and July 2015. Revision and conversion cases were excluded. Functional evaluations were performed using the Japanese Orthopaedic Association hip (JOA) score. Radiographic evaluations were performed using anteroposterior radiographs. Spot welds, radiolucency, cortical hypertrophy, and stress shielding around the stem were assessed for each Gruen zone. Subsidence and stem alignment were evaluated. ResultsThe 5-year postoperative stem survival rate was 100% in both groups. The JOA score improved from 44.0 ​± ​10.2 to 90.6 ​± ​7.6 in group I and from 49.1 ​± ​10.1 to 91.7 ​± ​6.6 in group II. There were no significant differences in preoperative and postoperative JOA scores and subscale scores in either group. Significant spot welds were observed in group II in Gruen zones 3 and 5. Stress shielding progressed over time in both groups, and the prevalence of grade 3 shielding was significantly lower in group II (p ​= ​0.028). ConclusionBoth stems had a survival rate of 100%. The incidence of severe stress shielding seemed to be lower with Accolade II, but further investigations should be needed.