Donald L. Pomeroy

Why are Total Knee Arthroplasties Being Revised

Despite technical improvements, revision rates for total knee arthroplasties (TKAs) remain high. Our goal was to report the reason(s) for revision TKA in a large, current, multicenter series and compare those reasons with previously published reasons. We retrospectively identified 820 consecutive revision TKAs (693 patients, 2000-2012) from our 3 centers and recorded the primary reason for the revision. The top seven reasons for the revision were aseptic loosening (23.1%), infection (18.4%), polyethylene wear (18.1%), instability (17.7%), pain/stiffness (9.3%), osteolysis (4.5%), and malposition/malalignment (2.9%). Comparison with previously published reasons showed fewer TKA revisions for polyethylene wear, osteolysis, instability, and malalignment. These changes may represent improvements in surgical technique and implants.

The Coventry Award Paper: Factors Influencing Wear and Osteolysis in Press-fit Condylar Modular Total Knee Replacements

The purpose of this study was to determine the factors influencing wear and osteolysis in patients who have had total knee arthroplasty with the Press-Fit Condylar modular system. Two-thousand ninety-one primary total knee replacements in 1737 patients were done using the Press-Fit Condylar system at three centers. Radiographic and manufacturing data were obtained for 2016 of the 2091 implants (96.4%). For the 1287 of 2016 knees (64%) with more than 5 years of followup, the prevalence of wear-related failure was 8.3%. The 13-year survivorship for all patients was 82.6%. Cox hazards analysis revealed five variables that were correlated with wear-related failure: patient age, patient gender, polyethylene sheet vendor, polyethylene finishing method, and polyethylene shelf age. We were unable to identify one factor as the defining reason for these wear-related failures. The multiple changes in manufacturing methods during the life of this implant may have precluded such a determination. These results may be specific to inserts sterilized in air with gamma irradiation and should not be generalized to current manufacturing techniques. This study emphasizes the potential deleterious effects that small changes in the manufacturing process may have on the outcome of a prosthesis with an initially favorable survivorship.

Midterm Results of All-Polyethylene Tibial Components in Primary Total Knee Arthroplasty

Our goal was to determine the 7-year survivorship of a total knee arthroplasty system with all-polyethylene tibial components. From June 1996 to December 1997, 129 consecutive patients (177 knees) (>/=70 years old) underwent such primary arthroplasty at 2 centers in the United States. The 88 patients (120 knees) with 7 years or more of follow-up were evaluated radiographically and functionally. Average results included: Knee Society Score, 93.7 points (SD, 8.1); Knee Society function score, 68.9 points (SD, 27.6); range of motion, 119 degrees (SD, 10.9); osteolysis, 0%; stress shielding, 6.6%; progressive radiolucencies, 2.5%; Kaplan-Meier survivorship (revision), 99.4% (95% confidence intervals, 98.2%-100.0%). At midterm follow-up, an all-polyethylene tibial component proved to be an excellent surgical option for total knee arthroplasty in an elderly patient population.

Tranexamic Acid Decreases Incidence of Blood Transfusion in Simultaneous Bilateral Total Knee Arthroplasty

Blood management for simultaneous bilateral total knee arthroplasty (TKA) patients is more challenging than in unilateral arthroplasty. We examined if administration of tranexamic acid (TXA) to patients undergoing simultaneous bilateral TKA would reduce blood loss and decrease allogeneic blood transfusion requirements. A retrospective review of 103 patients, 57 in the control and 46 in the TXA group, was performed. There was higher postoperative day 1 hemoglobin in patients receiving TXA (2.95±1.33 versus 4.33±1.19, P<0.0001). There was also a decrease in the transfusion incidence with administration of TXA (17.4% versus 57.9%, P<0.0001). In conclusion, we have shown that TXA is an effective tool in reducing the transfusion rates by almost 70% in simultaneous bilateral total knee arthroplasty.

In Vivo Performance of Moderately Crosslinked, Thermally Treated Polyethylene in a Prospective Randomized Controlled Primary Total Knee Arthroplasty Trial

Cross-linked bearings have been developed for use in total knee arthroplasty that exhibit improved wear properties, but at the expense of a decrease in mechanical strength of the cross-linked material. Adoption has been slow due to fears of mechanical failure secondary to this alteration in mechanical properties. This prospective, randomized study compared mid-term survivorship, clinical and radiographic results of a conventional polyethylene (GVF) to a cross-linked polyethylene (XLK) in total knee prostheses of the same design. At minimum 5-year follow-up there was no difference in survivorship, clinical performance or radiographic findings between the groups. There were no revisions for polyethylene wear, osteolysis or tibial insert dissociation. Most importantly, there were no revisions for mechanical failure or fracture of the polyethylene bearing in either group.