Abstract
The bearing surface is the critical element in determining the longevity of a total hip arthroplasty. Over the past decade problems associated with bearing surfaces and modular femoral tapers have had an impact on surgeon selection of both acetabular liners and modular femoral heads. The purpose of this study was to analyse THA bearing surface trends from 2007 through 2014 using a large national database.
A retrospective review of the Nationwide Inpatient Sample (NIS) database was conducted from 2007 to 2014. All patients who underwent a primary THA were identified using International Classification of Diseases, 9th edition (ICD-9) procedure codes. Bearing surface data was extracted by identifying patients with ICD-9 procedure modifier codes. Patient and hospital characteristics were recorded for each patient. Descriptive statistics were employed to characterise bearing surface trends for the following bearing surfaces: metal on polyethylene (MoP); ceramic on polyethylene (CoP); ceramic on ceramic (CoC) and metal on metal (MoM). Univariate analysis was performed to identify differences between the bearing surface groups.
During the study period, 2,460,640 primary THA discharges were identified, of which 1,059,825 (43.1%) had bearing surface data available for further analysis. The breakdown of the bearing surfaces used for these THAs were as follows: MoP − 49.1% (496,713); CoP − 29.1% (307,907); CoC − 4.2% (44,823); and MoM − 19.9% (210,381). MoM utilization peaked in 2008 with 51,033 cases representing 40.1% of THAs implanted that year. The usage steadily declined and by 2014 there were only 6,600 MoM cases representing only 4.0% of the THAs. From 2007 to 2014, the use of CoP bearing surfaces increased from 11,482 discharges (11.1% of cases) in 2007, to 83,300 discharges (50.8% of cases) in 2014. CoP utilization surpassed MoP in 2014. MoP accounted for 54.7% of discharges in 2011 and just 42.1% in 2014.
During the study period, MoM bearing surface usage declined precipitously, while CoP surpassed MoP as the most prevalent bearing surface used in total hip arthroplasty patients. These changes in bearing surface usage over time were clearly influenced by concerns regarding high failure rates associated with MoM articulations and reports of taper corrosion associated with modular metal femoral heads.
