Dual mobility bearings withstand loading from steeper cup‐inclinations without substantial wear

Abstract

Steep cup abduction angles with adverse joint loading may increase traditional polyethylene bearing wear in total hip arthroplasties. However, there have been few reports evaluating the effect of cup inclination on the wear of dual-mobility devices. In a hip joint simulation, we compared the short-term wear of two-sizes of modular highly cross-linked dual-mobility bearings (28 mm femoral head diameter/42 mm polyethylene insert outer diameter/54 mm acetabular shell diameter; 22.2 mm femoral head diameter/ 36 mm polyethylene insert outer diameter/48 mm acetabular shell diameter) at 50 and 65˚of cup inclination with modular 28 mm femoral head on 54 mm cup diameter metal-on-highly cross-linked polyethylene bearings. Increasing inclination from 50-65˚had no changes in volumetric wear of 28/42/54 mm (mean, 1.7 vs. 1.2 mm 3 /million cycles, respectively; p ¼ 0.50) and 22.2/36/48 mm (mean, 1.7 vs. 1.2 mm 3 /million cycles, respectively; p ¼ 0.48) dual mobility bearings. At 65˚, 22.2/36/48 mm dual-mobility bearings had lower volumetric loss (mean, 2.2 vs. 6.3 mm 3 ; p ¼ 0.03) and wear rates (mean, 1.2 vs. 2.7 mm 3 /million cycles; p ¼ 0.02) compared to metal-onhighly cross-linked polyethylene bearings. Modern-generation dual-mobility designs with highly cross-linked polyethylenes may potentially withstand edge-loading from steeper cup-inclinations without substantial decreases in wear. ß

Catastrophic failure of a dual mobility bearing in a revision total hip arthroplasty

“…Although studies have shown that in vitro testing of particular DM bearing sizes at an abduction angle of 65° does not increase wear, there have been no in vivo reports confirming this. In that same study, it was hypothesized that DM bearings may even withstand edge loading at steeper inclination cup abduction angles without a substantial increase in wear [10].…”

“…Looking at this question, Loving et al. [10], [11] found a significantly lower wear rate and volumetric loss with the 22.2-, 36-, or 48-mm DM bearings in comparison to single articulation THA at an inclination angles of 65° in vitro. Although this may be the case in vitro, we are unaware of any studies replicating these results in vivo [12].…”

Wear of dual-mobility cups: a review article

“…Wear rates were smaller than those with single articulation for each testing condition. In another study, [14] the same authors examined the influence of cup inclination (50°and 65°) on wear behavior of the HXLPE bearing surface. The authors found that steep cup inclination had no influence on poly wear in DM cups, exhibiting even better results compared with standard metalon-PE bearings.…”

“…Such complication was widely reported with the first-generation of DM bearings [7,8] but notably reduced-up to 0%-with newer-generation designs and adoption of smoother and thinner necks [9][10][11][12]. Moreover, the advent of highly cross-linked PE (HXLPE) seems to have improved this issue, as both in vitro tests [13,14] and early clinical data have shown encouraging results in comparison with conventional PE [15][16][17].…”

The dual mobility poly liner: A worthwhile articulation choice?

“…They are particularly useful for treatment of patients at high risk of dislocation, including those with femoral neck fractures [25,28,37,38] or spastic disorders [36]. There have been concerns with polyethylene wear [19,21,29,32] and intraprosthetic dislocation [19,30,32,[42][43][44][45][46]; however, improvements in polyethylene quality and component designs have reduced these risks [33,[47][48][49][50][51]. Dual mobility liners are perhaps best used in the revision setting for prevention of recurrent dislocation (Table 2).…”