Total knee arthroplasty in patients with severe obesity provides value for money despite increased complications

Cementless TKA use as an alternative to cemented TKA in high BMI patients: A systematic review and meta-analysis

Purpose

Obesity is prevalent, with nearly one-third of the world's population being classified as obese. In patients with high body mass index (BMI)/body mass undergoing total knee arthroplasty (TKA), there is an increase in strain placed on the implant fixation interfaces. As such, component fixation is a potential concern when performing TKA in the obese patient. To address the growing concerns around the longevity of implant fixation, some have advocated cementless over cemented fixation. However, there is no clear consensus on whether a cementless fixation has more favourable outcomes. The aim of this paper was to present a systematic review and meta-analysis of the existing evidence to establish if cementless TKA has a lower rate of aseptic loosening in high BMI patients when compared to cemented TKA procedures.

Methods

A systematic review was performed, and the following databases Medical Literature Analysis and Retrieval System Online (1946 to date), PubMed (1966 to date) and Excerpta Medica Database (1974 to date) were searched. All studies comparing cementless to cemented TKA in patients with BMI > 30 were considered. Meta-analysis compared aseptic loosening and all-cause revision between cemented and uncemented implant use in BMI > 30 patients.

Results

The search returned 91 articles in total; after duplicates were removed, the yield was 44 studies. Of the remaining studies that were assessed, three studies met the inclusion criteria for meta-analysis. The pooled odds ratio for all-cause revisions was 0.17 (95%, 0.08-0.36) in favour of uncemented implants (p < 0.01). The pooled odds ratio for aseptic loosening was 0.15 (95% confidence interval, 0.02-0.90) in favour of uncemented implants (p = 0.04).

Conclusions

Meta-analysis demonstrated a significant decrease in all-cause revisions and revisions for aseptic loosening when using uncemented fixation in high BMI patients when compared to the use of cemented implants.

Level of Evidence

The level of evidence is 1 for our systematic review.

Cost-utility analysis of total knee arthroplasty using 10-year data from a randomised controlled trial: Implant design influences quality-adjusted life year gain

BACKGROUND

The aim of this study was to perform a cost-utility analysis for total knee arthroplasty (TKA) over a 10-year follow up period.

METHODS

Two-hundred and twelve patients were randomised to receive either a Kinemax or a Triathlon TKA. Patients were assessed pre-operatively, and at 6 months, and 1, 3, 7 and 10 years postoperatively. The costs of the primary and revision surgery were accounted for. One-year quality-adjusted life year (QALY) gain was used to estimate 10-year gains using the established annual health gain discounts.

RESULTS

Forty-eight patients died and eight were revised during the follow up period. Overall QALY gain per patient over the 10-year period was 2.594 and the cost per patient was £6559, which resulted in a cost per QALY of £2761 at 10 years. The Triathlon group had a significantly greater QALY gain compared with the Kinemax (mean difference (MD) 0.53, 95% CI 0.03-1.03, P = 0.02), which resulted in a cost per QALY for the Triathlon group of £2521 compared with £3107 for the Kinemax group at 10 years. The 5% annual discount resulted in a significantly lower QALY gain (MD 0.135, 95% CI 0.201-0.354, P = 0.002), whereas the 3.5% annual discount resulted in non-significant difference in QALY gain compared with the actual gain (MD 0.021, 95% CI -0.084 to 0.077, P = 0.292).

CONCLUSIONS

TKA was a cost-effective intervention, and the Triathlon was associated with a greater cost effectiveness at 10 years. The 3.5% annual discounts for QALY gain would seem to be the most accurate, with an underestimation being observed with the 5% discount.

Total knee arthroplasty in patients with severe obesity: outcomes of standard keeled tibial components versus stemmed universal base plates

BACKGROUND

Patients with severe obesity [body mass index (BMI) ≥ 40 kg/m²] potentially overload the tibial component after total knee arthroplasty (TKA), risking tibial subsidence. Using a cemented single-radius cruciate-retaining TKA design, this study compared the outcomes of two tibial baseplate geometries in patients with BMI ≥ 40 kg/m²: standard keeled (SK) or universal base plate (UBP), which incorporates a stem.

METHODS

This was a retrospective, single-centre cohort study with minimum 2 years follow-up of 111 TKA patients with BMI ≥ 40 kg/m²: mean age 62.2 ± 8.0 (44-87) years, mean BMI 44.3 ± 4.6 (40-65.7) kg/m² and 82 (73.9%) females. Perioperative complications, reoperations, alignment and patient-reported outcomes (PROMS): EQ-5D, Oxford Knee Score (OKS), Visual Analogue Scale (VAS) pain score and satisfaction were collected preoperatively, and at 1 year and final follow-up postoperatively.

RESULTS

Mean follow-up was 4.9 years. SK tibial baseplates were performed in 57 and UBP in 54. There were no significant differences in baseline patient characteristics, post-operative alignment, post-operative PROMs, reoperations or revisions between the groups. Three early failures requiring revision occurred: two septic failures in the UBP group and one early tibial loosening in the SK group. Five-year Kaplan-Meier survival for the endpoint mechanical tibial failure was SK 98.1 [94.4-100 95% confidence interval (CI)] and UBP 100% (p = 0.391). Overall varus alignment of the limb (p = 0.005) or the tibial component (p = 0.031) was significantly associated with revision and return to theatre.

CONCLUSIONS

At early to mid-term follow-up, no significant differences in outcomes were found between standard and UBP tibial components in patients with BMI ≥ 40 kg/m². Varus alignment of either tibial component or the limb was associated with revision and return to theatre.