Survival analysis of the femoral component retained in isolated acetabular revision of the hip prosthesis

Introduction Isolated acetabular revision with the retention of a well-fixed and aligned femoral component is the priority treatment method in aseptic acetabular loosening. The aim of the research was to predict the survival rate of a well-fixed and aligned femoral component retained during the isolated acetabular revision surgery. Material and methods We used the survival tables and the Kaplan-Meier method to create the survival curves. The object of the study was the database of 44 patients (45 interventions) who underwent isolated acetabular revision surgeries with their well-fixed and aligned femoral components that was retained. The average age of the patients was 59.5 [50; 69.5] years. The ratio of women to men was 25:19, respectively. The observation period was 1374 days. The creation of tables and graphs was carried out in Statistica 13.3 software package. Results The survival rate of the retained well-fixed and aligned femoral component in isolated acetabular revision within the period up to 4 years was high and amounted to 0.9524 ± 0.03. The probability density and the hazard rates were 0.0017 and 0.00320, respectively. Discussion The retention of a well-fixed and aligned stem in acetabular revision features high survival of the components as well as a low risk of endoprosthesis failure within 3 to 4 years. This fact confirms the need to maintain a stable and correctly oriented stem to reduce the surgical trauma, obtain good functional results and reduce rehabilitation terms. Conclusion Isolated acetabular revision in isolated aseptic cup loosening is a priority method of surgical treatment with a low risk of complications in the postoperative period.

Is there a problem with modular dual mobility acetabular components in revision total hip arthroplasty at mid-term follow-up?

Aims Modular dual mobility (MDM) acetabular components are often used with the aim of reducing the risk of dislocation in revision total hip arthroplasty (THA). There is, however, little information in the literature about its use in this context. The aim of this study, therefore, was to evaluate the outcomes in a cohort of patients in whom MDM components were used at revision THA, with a mean follow-up of more than five years. Methods Using the database of a single academic centre, 126 revision THAs in 117 patients using a single design of an MDM acetabular component were retrospectively reviewed. A total of 94 revision THAs in 88 patients with a mean follow-up of 5.5 years were included in the study. Survivorship was analyzed with the endpoints of dislocation, reoperation for dislocation, acetabular revision for aseptic loosening, and acetabular revision for any reason. The secondary endpoints were surgical complications and the radiological outcome. Results The overall rate of dislocation was 11%, with a six-year survival of 91%. Reoperation for dislocation was performed in seven patients (7%), with a six-year survival of 94%. The dislocations were early (at a mean of 33 days) in six patients, and late (at a mean of 4.3 years) in four patients. There were three intraprosthetic dissociations. An outer head diameter of ≥ 48 mm was associated with a lower risk of dislocation (p = 0.013). Lumbrosacral fusion was associated with increased dislocation (p = 0.004). Four revision THAs (4%) were further revised for aseptic acetabular loosening, and severe bone loss (Paprosky III) at the time of the initial revision was significantly associated with further revision for aseptic acetabular loosening (p = 0.008). Fourteen acetabular components (15%) were re-revised for infection, and a pre-revision diagnosis of reimplantation after periprosthetic joint infection (PJI) was associated with subsequent PJI (p < 0.001). Two THAs had visible metallic changes on the backside of the cobalt chromium liner. Conclusion When using this MDM component in revision THA, at a mean follow-up of 5.5 years, there was a higher rate of dislocation (11%) than previously reported. The size of the outer bearing was related to the risk of dislocation. There was a low rate of aseptic acetabular loosening. Longer follow-up of this MDM component and evaluation of other designs are warranted. Cite this article: Bone Joint J 2021;103-B(7 Supple B):66–72.