Liner malseating is rare with two modular dual-mobility designs

Abstract

Aims The aim of this study was to evaluate the incidence of liner malseating in two commonly used dual-mobility (DM) designs. Secondary aims included determining the risk of dislocation, survival, and clinical outcomes. Methods We retrospectively identified 256 primary total hip arthroplasties (THAs) that included a DM component (144 Stryker MDM and 112 Zimmer-Biomet G7) in 233 patients, performed between January 2012 and December 2019. Postoperative radiographs were reviewed independently for malseating of the liner by five reviewers. The mean age of the patients at the time of THA was 66 years (18 to 93), 166 (65%) were female, and the mean BMI was 30 kg/m2 (17 to 57). The mean follow-up was 3.5 years (2.0 to 9.2). Results Three liners (1.2%) were malseated, including two MDMs (1.4%) and one G7 (0.9%). No clinical consequence was identified from malseating. The five-year survival free of dislocation was 97.1%, including two DM and one intraprosthetic dislocation. The five-year survival free of revision was 95.4%, with seven revisions. The mean Harris Hip Scores increased from 46 (24 to 69) preoperatively to 81 (40 to 100) at two years postoperatively (p < 0.001). Conclusion The incidence of DM liner malseating after primary THA was low, with no known clinical consequences at mid-term follow-up. Malseating is not exclusive of design, and these findings emphasize the importance of careful evaluation of the liner after impaction to avoid this complication. Cite this article: Bone Joint J 2022;104-B(5):598–603.

No clinical consequence of liner malseating in dual-mobility THAs at short term: a systematic review

“…After removal of duplicates, 17 articles were screened for study inclusion, and 12 records considered to be possibly eligible based on their title. After exclusion of 7 studies on non-dual-mobility THAs, 5 retrospective cohort studies, published between 2019 and 2021, were included in the final analysis (Table 1) [6,[12][13][14][15]. Except one multicenter study, all were single institution cohorts, and all conducted at major university-based US institutions between 2010 and 2020.…”

“…Patients without both an AP and cross table lateral radiograph were excluded in all studies. Radiographic follow-up was précised by 3 studies only, with two using a minimum of 6 weeks [ 6 , 15 ], one reporting of a mean follow-up of 6 and 10 months for Stryker and Zimmer Biomet implants, respectively [ 13 ]. Liner malseating was defined in 4 studies, with all proposing a similar definition of gap, asymmetry, angulation, or disruption between liner and acetabular component [ 6 , 12 , 13 , 15 ].…”

“…Liner malseating in dual-mobility THAs Guntin et al [12] Siljander et al, [13] Salem et al [14] Chalmers et al [15] Romero et al [ with Biomet Zimmer shells (2.14%; Fig. 3).…”

“…Differentiation based on sex was performed in 2 studies, with 35 malseatings occurring in females, 9 in men [6,12]. Clinical follow-up was described inconsistently among studies with 3 reporting of a mean follow-up (overall mean 2.2 years) [12,13,15], 4 including a minimum follow-up (overall mean 1.27 years) [12][13][14][15], and another 4 reporting of a maximum follow-up (overall mean 6.36 years) [6,12,13,15]. Except one patient reporting of pain at 2 years [6], no clinical consequence was noted in the group of malseated liners, including no revision or negatively impacted functionality.…”

Dual Mobility for Oncological Hip Reconstruction: Significantly Reduced Dislocation Rates at 5 years

“…Unrevised cases with radiographs taken at least 1 week postoperatively were analyzed for (1) zones of progressive radiolucency, as described by Gruen et al 17 for femoral components and by DeLee et al 18 for sockets, (2) definite radiographic signs of loosening based on Fowler 19 and Zweymüller et al, 20 and (3) signs of liner malseating and intraprosthetic dislocation in case of DMs. 21,22 European Cooperative Oncology Group (ECOG) 23 scores were obtained as a reflection of functionality status, and patients classified as (0) asymptomatic, (1) completely ambulatory, (2) less than 50% bedbound, (3) more than 50% bedbound, (4) bedbound, and (5) dead.…”