Mid-term survivorship and clinical outcomes of revision knee arthroplasty using a mobile bearing tibial tray: A single-center registry review.

BACKGROUND: Revision total knee arthroplasty can successfully restore function and relieve pain for patients with failed knee replacements. Mobile-bearing implants were designed to provide greater congruency between the implant and the polyethylene insert. The goal of this study was to review the clinical outcomes and survivorship for a revision mobile-bearing tibial design. METHODS: A retrospective outcomes review was conducted to assess survivorship and clinical outcomes for a mobile bearing tibial tray, used with metaphyseal sleeves, in revision total knee arthroplasty. RESULTS: At time of furthest follow-up, KM estimates (95% CI; n with further follow-up) for all-cause revision were 82.5% (75.8%; 87.5%; 42) at 7 years for the clinical assumption (CA), and 88.5% (84.4%,91.6%; 53) at 13 years for the registry assumption (RA). For revision of the tray as the endpoint, survivorship estimates were 93.4% (87.0%,96.7%; 42) at 7 years for CA, and 96.2% (93.2%,97.9%; 53) at 13 years for RA. CONCLUSION: In this single-center registry evaluation, we found excellent mid-term survivorship and clinical outcomes for a mobile-bearing tibial tray used with metaphyseal sleeves in revision total knee arthroplasty.

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.

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.

Comparison of patient-reported and clinician-assessed outcomes following total knee arthroplasty.

BACKGROUND: Although the necessity of long-term follow-up after total knee arthroplasty is unquestioned, this task may become burdensome as greater numbers of total knee arthroplasties are performed. We sought to use comparisons with clinician-assessed values to determine whether patients could reliably assess their own outcome with use of a combination of American Knee Society Score and Oxford Knee Score questionnaires and self-reported knee motion. We hypothesized that patients would self-report worse pain and function and a similar range of knee motion than clinicians would. METHODS: One hundred and forty patients (181 knees) scheduled for routine follow-up at two centers after primary total knee arthroplasty were mailed American Knee Society Score and Oxford Knee Score questionnaires, a set of photographs illustrating knee motion in 5° increments for comparison with the patient's range of knee motion, and a goniometer with instructions. The patient's American Knee Society Score, Oxford Knee Score, and knee motion were then independently assessed within two weeks of the self-evaluation by one of three clinicians who had not been involved with the surgery. Patient-reported and clinician-assessed measures were compared with use of a paired-sample t test and the Spearman correlation coefficient. RESULTS: The mean patient-reported American Knee Society pain subscore was 4 points worse than the clinician-assessed score, and the function subscore was 10 points worse (p < 0.001 for both). The mean Oxford Knee Score did not differ significantly between the patient self-assessment and the clinician assessment (p = 0.05). The mean maximum flexion reported by the patient with use of the photographs differed by <1° from the mean value reported by the patient with use of the goniometer or the mean value measured by the clinician; these differences were not clinically important. CONCLUSIONS: Patients' self-reported American Knee Society pain and function subscores were worse than the corresponding clinician assessments, but the two Oxford Knee Scores were similar. Range of knee motion may reasonably be self-assessed by comparison with photographs. Long-term follow-up of patients after total knee arthroplasty may be possible with use of patient-reported measures, alleviating the burden of clinic visits yet maintaining contact, but further studies involving other validated instruments is warranted.

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.

Sterilization and wear-related failure in first- and second-generation press-fit condylar total knee arthroplasty.

UNLABELLED: We compared the incidence of wear-related failures between two large cohorts of patients undergoing total knee arthroplasty implanted with identical modular tibial trays and polyethylene inserts sterilized by different methods. A total of 1183 second-generation press-fit condylar prostheses having inserts packaged and sterilized in an oxygen-free environment were assessed at a minimum 5-year followup (mean, 7.0 years). Wear-related failure was defined as (1) osteolysis greater than 100 mm2 or (2) revision of the implant resulting from osteolysis, polyethylene wear, chronic synovitis, and/or effusion. Wear-related survivorship was calculated using Kaplan-Meier survival analysis. Results were compared with our previously published study of 1287 first-generation press-fit condylar modular knees having inserts sterilized by gamma irradiation in air at 5-year minimum followup (mean, 7.8 years). The wear-related failure rate for the second-generation design was 1.1% and 10-year survivorship was 97.0% compared with 8.3% failure and 87.7% 10-year survival for the first-generation design. For second-generation components, patient age was the only variable correlated with wear-related failure. For first-generation components sterilized in air, several variables were correlated to wear-related failure with shelf age of the polyethylene insert being the most important factor. These data emphasize the dramatic effect improvements in polyethylene manufacturing, specifically sterilization methods, can have on implant survivorship. LEVEL OF EVIDENCE: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

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.