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

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).

In-Hospital Acute Kidney Injury After TKA Revision With Placement of an Antibiotic Cement Spacer.

BACKGROUND: There is mounting evidence that treatment of periprosthetic joint infection of the knee with an antibiotic cement spacer (ACS) may increase risk for acute kidney injury (AKI). We sought to determine the incidence, as well as potential risk factors, of in-hospital AKI in this cohort. METHODS: We retrospectively identified 75 patients that received either a static or articulating ACS at a single institution. In-hospital AKI was defined by a more than 50% rise in serum creatinine from preoperative baseline to at least 1.4 mg/dL. Our secondary outcome was percent change in creatinine from preoperative to peak postoperative value. Variables were analyzed for the outcome of AKI with univariate logistic regression. A final multivariate model for percent change in creatinine was formed while controlling for age, gender, body mass index, and baseline creatinine. RESULTS: The incidence of AKI was 14.6%, occurring at a mean of 6.3 days (2-8 days). A lower preoperative hemoglobin (odds ratio = 1.82, P = .015) significantly increased risk for AKI on univariate analysis. Diagnosis of either hypertension or diabetes also showed a strong statistical trend (P = .056). On multivariate regression, lower preoperative hemoglobin significantly correlated with a greater percent rise in creatinine postoperatively (ß = 0.30, P = .015). CONCLUSION: The incidence of AKI in patients who receive ACS is relatively high, raising clinical concern in the care of periprosthetic joint infection patients. Our results suggest that a lower baseline hemoglobin may be involved in the etiology of AKI in this population. Therefore, it may be clinically appropriate to monitor anemic patients for AKI when implanting an ACS.

Aseptic Tibial Implant Loosening After Total Knee Arthroplasty: Preventable?

Aseptic loosening is a considerable complication that affects the longevity of total knee arthroplasty (TKA) implants. Surgeon technique may help minimize aseptic loosening after TKA. Meticulous cementation of the prosthesis and the bone surface during various stages of cement polymerization will maximize cement adherence to the prosthesis and the bone, respectively. Pressurization of the cement in the canal and at the cut surface to achieve at least 2 mm of cement depth penetration has been reported to increase TKA implant longevity.