Aseptic Loosening at the Tibia in Total Knee Arthroplasty: A Function of Cement Mantle Quality?

ABSTRACT

BACKGROUND: Aseptic loosening remains one of the leading causes for failure of total knee arthroplasty (TKA). We sought to identify early radiographic measures that may associate with aseptic tibial component loosening, emphasizing systematic evaluation of the cement mantle. METHODS: All TKA revisions from 2007 to 2015 with the primary indication of tibial aseptic loosening were identified using in an institutional implant retrieval database. After exclusion criteria, 61 TKAs comprised the study group. A matched control group of 59 TKAs that had not failed at a minimum of 3 years was identified for comparison. Radiographic analysis on all 6-week postoperative radiographs included angulation of components, cement penetration depth, and presence of radiolucency at the implant-cement and bone-cement interfaces. Groups were compared with Student's t-test, chi-squared test, and Mann-Whitney U-test. A final multivariable logistic regression model was formed for the outcome of aseptic loosening. RESULTS: On multivariable analysis, failure was associated with a greater number of zones with cement penetration <2 mm (5.6 vs 3.4 zones, odds ratio [OR] 1.89, P < .001), increasing percent involvement of radiolucency at the implant-cement interface (8.7% vs 3.1%, OR = 1.15, P = .001), and increased varus alignment of the tibial component (1.5° vs 0°, OR = 1.35, P = .014). A greater number of zones with a radiolucent line at the bone-cement interface did not significantly associate (1.1 vs 0.3, P = .091). CONCLUSION: Our results suggest that radiographic indicators of poor cement mantle quality associate with later aseptic loosening. This emphasizes the need for surgeons to perform careful cement technique in order to reduce the risk of TKA failure. LEVEL OF EVIDENCE III (Case-control).