Higher body mass index is associated with larger postoperative improvement in patient-reported outcomes following total knee arthroplasty

BACKGROUND

Total knee arthroplasty is known to successfully alleviate pain and improve function in endstage knee osteoarthritis. However, there is some controversy with regard to the influence of obesity on clinical benefits after TKA. The aim of this study was to investigate the impact of body mass index (BMI) on improvement in pain, function and general health status following total knee arthroplasty (TKA).

METHODS

A single-centre retrospective analysis of primary TKAs performed between 2006 and 2016 was performed. Data were collected preoperatively and 12-month postoperatively using WOMAC score and EQ-5D. Longitudinal score change was compared across the BMI categories identified by the World Health Organization.

RESULTS

Data from 1565 patients [mean age 69.1, 62.2% women] were accessed. Weight distribution was: 21.2% BMI < 25.0 kg/m2, 36.9% BMI 25.0-29.9 kg/m2, 27.0% BMI 30.0-34.9 kg/m2, 10.2% BMI 35.0-39.9 kg/m2, and 4.6% BMI ≥ 40.0 kg/m2. All outcome measures improved between preoperative and 12-month follow-up (p < 0.001). In pairwise comparisons against normal weight patients, patients with class I-II obesity showed larger improvement on the WOMAC function and total score. For WOMAC pain improvements were larger for all three obesity classes.

CONCLUSIONS

Post-operative improvement in joint-specific outcomes was larger in obese patients compared to normal weight patients. These findings suggest that obese patients may have the greatest benefits from TKA with regard to function and pain relief one year post-op. Well balanced treatment decisions should fully account for both: Higher benefits in terms of pain relief and function as well as increased potential risks and complications. Trial registration This trial has been registered with the ethics committee of Eastern Switzerland (EKOS; Project-ID: EKOS 2020-00,879).

Overview, history, evaluation and future developments of the AutoGrouper 16-C

This paper presents an overview and history of the Technicon blood-grouping machine from the first single-channel AutoAnalyser of 1963 through to the new, fully automated AutoGrouper 16-C. The report includes an analysis of facts drawn from a detailed evaluation of the AutoGrouper 16-C including its installation, performance, reliability, simplicity of operation, detection of irregular antibodies, syphilis screening, use of reagents and a brief cost analysis.

Automated readout of sample identification and test results in a BG-8 blood grouping machine

A fully automated readout unit for the BG-8 blood-grouping machine, printing Idee identification numbers with matching ABO grouping and rhesus (D) typing results is described. In 6,737 samples, no incorrect blood group was recorded. Two rhesus (D) positive samples were overlooked, however, and 16.4% of the samples had to be retested because of irregular reaction patterns. Better results are to be expected with properly selected test cells and anti-D serum. The readout unit is easily operated and is not disturbed by clots. The additional equipment needed replaces the modules which were necessary for recording on filter paper.

Automated readout of the BG-8 blood-grouping machine. Results of 10,000 blood group and 4,000 rhesus D factor determinations

An automated readout device recording light transmission in the eight channels of the BG-8, blood-grouping machine after removal of agglutinates is described. Using a continuous recording of positive or negative signals in the eight channels independently, 7.5% of 10,000 blood group determinations had to be retested because of clots in the samples, lacking reactions or excess reactions on the recorder. No incorrect recordings of blood groups were obtained, however. Using anti-D serum together with anti-CDE serum, the rhesus D factor was correctly detected in 99.92% of 3,891 samples, and the Du factor was detected in all 5 samples known to carry this antigen. Using a discontinuous recording of integrated and synchronised signals, adapted to fully automated data processing, another 5% of the samples had to be retested because of inadequate phasing of the reactions in the eight channels of the BQ-8. The results described are influenced by the poor quality of the blood samples used for the study.