2020 Otto Aufranc Award: Malseating of modular dual mobility liners

Abstract

Aims This combined clinical and in vitro study aimed to determine the incidence of liner malseating in modular dual mobility (MDM) constructs in primary total hip arthroplasties (THAs) from a large volume arthroplasty centre, and determine whether malseating increases the potential for fretting and corrosion at the modular metal interface in malseated MDM constructs using a simulated corrosion chamber. Methods For the clinical arm of the study, observers independently reviewed postoperative radiographs of 551 primary THAs using MDM constructs from a single manufacturer over a three-year period, to identify the incidence of MDM liner-shell malseating. Multivariable logistic regression analysis was performed to identify risk factors including age, sex, body mass index (BMI), cup design, cup size, and the MDM case volume of the surgeon. For the in vitro arm, six pristine MDM implants with cobalt-chrome liners were tested in a simulated corrosion chamber. Three were well-seated and three were malseated with 6° of canting. The liner-shell couples underwent cyclic loading of increasing magnitudes. Fretting current was measured throughout testing and the onset of fretting load was determined by analyzing the increase in average current. Results The radiological review identified that 32 of 551 MDM liners (5.8%) were malseated. Malseating was noted in all of the three different cup designs. The incidence of malseating was significantly higher in low-volume MDM surgeons than high-volume MDM surgeons (p < 0.001). Pristine well-seated liners showed significantly lower fretting current values at all peak loads greater than 800 N (p < 0.044). Malseated liner-shell couples had lower fretting onset loads at 2,400 N. Conclusion MDM malseating remains an issue that can occur in at least one in 20 patients at a high-volume arthroplasty centre. The onset of fretting and increased fretting current throughout loading cycles suggests susceptibility to corrosion when this occurs. These results support the hypothesis that malseated liners may be at risk for fretting corrosion. Clinicians should be aware of this phenomenon. Cite this article: Bone Joint J 2020;102-B(7 Supple B):20–26.

Implant survival of 662 dual-mobility cups and 727 constrained liners in primary THA: small femoral head size increases the cumulative incidence of revision

“…As a result, size of the dual-mobility head is smaller in Trident than in the 1-piece cup DMC designs. The Trident has also been associated with a risk of mal-insertion of the liner (Langdown et al 2007, Romero et al 2020. The "DMC Trident group" included all Trident DMCs (n = 399), and the "DMC Others group" (n = 263) included the rest of the DMCs.…”

Adverse reaction to metal debris due to fretting corrosion between the acetabular components of modular dual-mobility constructs in total hip replacement: a systematic review and meta-analysis

“…Screening by title and abstract excluded a further 21, leaving 32 articles which underwent full-text review. Out of these, 16 were identified for overall inclusion 16 - 31 ( Fig. 1 32 ), with meta-analysis performed on specific subsets as described below.…”

“…Another theory is provided by the radiographic study of 551 cases, finding that 5.8% of MDM liners were malseated on retrospective evaluation. 31 Subsequent in vitro modelling in the same study suggested that liner malseating can lead to lower fretting onset loads. Taken together, these results corroborate findings by Kolz et al 30 describing three different patterns of wear, and suggest that debris generation in MDM constructs is likely a combination of intrinsic (component design) and extrinsic (surgical) factors.…”

Modular Dual-Mobility Liner Malseating: A Radiographic Analysis

“…Otherwise, the incidence of the problem may have been higher and corroborating studies are needed in this regard. By comparison, we are aware of one study that demonstrated an incidence of MDM liner malseating of 5.8% in a cohort of patients who underwent THA, in which the surgery was performed by 17 surgeons, where routine liner testing was not performed [ 18 ]. Furthermore, it was previously noted by Miller et al.…”

“…However, added modularity introduces additional potential complications, including modular liner malseating and/or dissociation and intraprosthetic dislocation (IPD) [ 16 , 17 ]. The notion that a stiff cobalt-chrome liner has a potentially higher risk of malseating because of less-conforming tolerance than that of polyethylene is supported by experiences with incomplete seating of the liner with metal-backed ceramic liners [ 18 , 19 ]. However, there is a paucity of data on modular dual-mobility (MDM) liners incompletely seating, any untoward consequences, and how to minimize and manage the occurrence [ 20 ].…”