Comparison of patient reported outcomes after Triathlon(®) and Kinemax Plus prostheses

Conventional Versus Highly Cross-Linked Polyethylene in Primary Total Knee Replacement: A Comparison of Revision Rates Using Data from the National Joint Registry for England, Wales, and Northern Ireland

BACKGROUND

There is evidence to support the use of highly cross-linked polyethylene (HXLPE) in patients undergoing total hip arthroplasty. However, the benefits for those undergoing total knee arthroplasty are uncertain, with conflicting reports based on previous cohort analyses. The purpose of the present study was to compare the revision rates following primary total knee arthroplasty with use of HXLPE as compared with conventional polyethylene (CPE) using data from the National Joint Registry (NJR) for England, Wales and Northern Ireland.

METHODS

We performed a retrospective analysis of primary total knee arthroplasties recorded in the NJR from 2003 to 2014. Cobalt-chromium (CoCr)-CPE and CoCr-HXLPE bearing surfaces were compared using all-cause revision, aseptic revision, and septic revision as end points. Survival analyses were conducted using rates per 100 years observed, Kaplan-Meier survival estimates, and Cox regression hazard ratios (HRs) adjusted for age, sex, American Society of Anesthesiologists (ASA) classification, body mass index (BMI), lead surgeon grade, and implant constraint. Secondary analyses compared the most commonly used HXLPEs (Zimmer Prolong, DePuy XLK, and Stryker X3) against CPE for the 3 most common total knee arthroplasty systems (NexGen, PFC Sigma, and Triathlon).

RESULTS

In the present study of 550,658 total knee arthroplasties, the unadjusted aseptic revision rates were significantly lower following procedures performed with CPE (n = 513,744) as compared with those performed with HXLPE total knee replacements (n = 36,914) (0.29 [95% confidence interval (CI), 0.28 to 0.30] compared to 0.38 [95% CI, 0.35 to 0.42], p < 0.01). The 10-year HR associated with CPE was 0.4 (95% CI, 0.1 to 0.8, p = 0.03). There were no significant differences between the adjusted revision rates of HXPLE compared with CPE in individual analyses of the most common total knee arthroplasty systems. However, for the subset of patients who were both <60 years of age and had a BMI of >35 kg/m, the "second-generation" Stryker X3 HXLPE demonstrated significantly better survival than its respective CPE, with CPE having an HR of 2.6 (95% CI, 1.2 to 5.9) (p = 0.02).

CONCLUSIONS

Alternative bearings are marketed as having improved wear properties over traditional CoCr-CPE. This registry-based analysis demonstrated no overall survival benefit of HXLPE after a maximum duration of follow-up of 12 years. Because of their increased cost, the routine use of HXLPE bearings may not be justified. However, they may have a role in specific "higher demand" groups such as patients <60 years of age and/or those with a BMI of >35 kg/m.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete list of levels of evidence.

Excellent 10-year patient-reported outcomes and survival in a single-radius, cruciate-retaining total knee arthroplasty

PURPOSE

Over 2 million Triathlon single-radius total knee arthroplasties (TKAs) have been implanted worldwide. This study reports the 10-year survival and patient-reported outcome of the Triathlon TKA in a single independent centre.

METHODS

From 2006 to 2007, 462 consecutive cruciate-retaining Triathlon TKAs were implanted in 426 patients (median age 69 (21-89), 289 (62.5%) female). Patellae were not routinely resurfaced. Patient-reported outcome measures (SF-12, Oxford Knee Scores (OKS), satisfaction) were assessed preoperatively and at 1, 5 and 10 years when radiographs were reviewed. Forgotten Joint Scores (FJS) were collected at 10 years. Kaplan-Meier survival analysis was performed.

RESULTS

At 10-11.6 years, 123 patients (128 TKAs) had died and 8 TKAs were lost to follow-up. There were four aseptic failures (two cases of tibial loosening, two cases of instability) and four septic failures requiring revision. Symptomatic aseptic radiographic loosening was present in three further cases at 11 years. Four (1%) patellae were secondarily resurfaced. OKS score improved by 17.7 ± 9.7 points at 1 year (p < 0.001), and was maintained at 34.7 ± 9.6 at 10 years with FJS 48.5 ± 31.4. Patient satisfaction was 88% at each timepoint. Ten-year survival was 97.9% (95% confidence interval 96.5-99.3) for revision for any reason, 98.9% (97.7-100) for mechanical failure, and 98.6% (97.4-99.8) for aseptic loosening (symptomatic radiographic or revised).

CONCLUSION

The Triathlon TKA continues to show excellent longer-term results with high implant survivorship, low rates of aseptic failure, consistently maintained PROMs and excellent patient satisfaction rates of 88% at 10 years.

LEVEL OF EVIDENCE

II, Prospective cohort study.

Prospective Randomized Comparison of Posterior-Stabilized Versus Condylar-Stabilized Total Knee Arthroplasty: Final Report of a Five-Year Study

BACKGROUND

This report presents the minimum 5-year results of a prospective, randomized, Level of Evidence I study that evaluated cruciate-sacrificing total knee arthroplasty using either a posterior-stabilized (PS) device or a condylar-stabilized (CS) device. We hypothesized that the clinical outcomes of both groups would be equivalent and that there would be differences in operative time and/or blood loss parameters.

METHODS

One-hundred eleven patients undergoing total knee arthroplasty were randomized to receive either a post-cam style tibial insert (PS, n = 56) or a more congruent anterior-lipped tibial insert (CS, n = 55). All posterior cruciate ligaments were sacrificed.

RESULTS

Comparison of the clinical scores and radiographic results between both groups were essentially equivalent with no statistically significant differences at the final 5-year evaluation, although the CS knee group had significantly fewer incidences of postoperative mechanical sensations (P = .01).

CONCLUSION

These results demonstrate that the CS knee provides excellent clinical, functional, and radiographic outcomes that are comparable to the results achieved with the PS knee, with a lower incidence of mechanical sensations, and support the use of a CS device as an alternative to the PS device.

Perioperative and Early Postoperative Comparison of a Modern Cemented and Cementless Total Knee Arthroplasty of the Same Design

BACKGROUND

Cementless total knee arthroplasty (TKA) designs that incorporate a highly porous, titanium surface have the potential to achieve biologic fixation and improve component survivorship. This study's purpose was to compare perioperative and early postoperative outcomes of a cemented vs cementless TKA of the same design.

METHODS

This was a retrospective review of a consecutive series of TKAs performed at a single institution using a cemented or cementless TKA of the same design (Triathlon, Stryker Inc, Mahwah, NJ). All patients with a minimum of 1-year clinical and radiographic follow-up were reviewed, with 1:1 matching performed for age, gender, body mass index, and preoperative Oxford Knee Score. Chi-square or independent student t tests were used for statistical analyses.

RESULTS

Overall, 62 cemented and 66 cementless TKAs were reviewed, with secondary analyses performed after 1:1 matching of 38 patients in each cohort. In both overall and secondary 1:1 matching analyses, there was no difference in baseline demographics (P = .6-.9). Total operative times were decreased in the cementless cohort (P = .03), but there was no difference in the estimated blood loss or change in hemoglobin levels (P = .2-.7). At a mean of 1.4 ± .5 years postoperatively, patients in both cohorts demonstrated similar improvements in Oxford Knee Scores and satisfaction scores (P = .2-.8), with no patients requiring a revision surgical procedure.

CONCLUSION

A recently introduced cementless TKA design demonstrates excellent perioperative and early postoperative results without failures. Continued surveillance is necessary to elucidate the survivorship and potential long-term benefits of this cementless design.

Outcome Assessment in Total Knee Arthroplasty: A Systematic Review and Critical Appraisal

BACKGROUND

The Outcome Measures in Rheumatology (OMERACT) initiative developed a core outcome set (COS) of domains to assess effectiveness of interventions for knee osteoarthritis. These domains (pain, physical function, patient global assessment, imaging at 1 year) should be assessed in every trial to make research evidence meaningful and comparable. We systematically evaluated and critically appraised the use of measurement instruments and outcome domains in prospective studies evaluating patients with knee osteoarthritis undergoing total knee arthroplasty (TKA) and assessed their accordance with the OMERACT COS.

METHODS

Literature search was performed until August 26, 2014, in Medline and Embase. Clinical trials and prospective observational studies with ≥50 participants and a follow-up of ≥1 year were included. We collected general study characteristics, comprehensive information on measurement instruments, and corresponding domains used.

RESULTS

This systematic review identified low accordance of used outcome domains with the OMERACT COS of domains published in 1997. Only 4 of 100 included studies included all recommended core domains. Pain (85% of studies) and physical function (86%) were assessed frequently, whereas patient global assessment (21%) and joint imaging (≥1 year; 27%) were rarely assessed. There was substantial heterogeneity in the use of measurement instruments (n = 111) investigating TKA.

CONCLUSION

More efforts are required to implement the existing COS. In addition, a more consistent use of adequate measurement instruments is important to make research evidence on TKA more relevant, better comparable, and thus more useful for guideline developers and clinical decision makers.