Less wear in deep-dished mobile compared to fixed bearing total knee arthroplasty of the same design at 5-year follow-up: a randomised controlled model-based Roentgen stereophotogrammetric analysis trial

PURPOSE

The aim of this prospective randomised controlled study was to compare wear characteristics and functional outcome between deep-dished mobile bearing (MB) and fixed bearing (FB) cemented total knee arthroplasty (TKA). We hypothesised that deep-dished MB reduces polyethylene wear and improves patient-reported outcome measures.

METHODS

A total of 50 patients were randomised to receive a MB or FB tibia component of the same cemented TKA design. Patients were evaluated over a 5-year follow-up period. Medial and lateral wear were assessed using model-based Roentgen Stereophotogrammetric Analysis (RSA) and compared with the direct postoperative minimal joint space measurement. Functional outcome was assessed by the clinician-derived KSS and OKS, WOMAC, LEAS, and FJS-12. All data were derived using a general linear mixed model.

RESULTS

At 5-year follow-up, decreased wear in the MB compared to the FB group was observed on the lateral side (0.07 ± 0.17 mm, p = 0.026), but not on the medial side (0.31 ± 0.055 mm, p = 0.665). Functional outcomes improved with a statistical significant effect over time, with no significant differences between groups (all p > 0.17).

CONCLUSION

This model-based RSA study with 5-year follow-up showed that cemented deep-dished MB reduced lateral polyethylene wear as compared to FB in a single TKA system, whilst clinical outcomes were comparable. Longer follow-up is needed to establish clinical implications of these altered wear patterns and determine type of wear.

LEVEL OF EVIDENCE

Level 1 randomised controlled trial.

Gut microbiota composition strongly correlates to peripheral insulin sensitivity in obese men but not in women

Gut microbiota composition may play an important role in the development of obesity-related comorbidities. However, only few studies have investigated gender-differences in microbiota composition and gender-specific associations between microbiota or microbial products and insulin sensitivity. Insulin sensitivity (hyperinsulinemic-euglycemic clamp), body composition (dual energy X-ray absorptiometry), substrate oxidation (indirect calorimetry), systemic inflammatory markers and microbiota composition (PCR) were determined in male (n=15) and female (n=14) overweight and obese subjects. Bacteroidetes/Firmicutes-ratio was higher in men than in women (P=0.001). Bacteroidetes/Firmicutes-ratio was inversely related to peripheral insulin sensitivity only in men (men: P=0.003, women: P=0.882). This association between Bacteroidetes/Firmicutes-ratio and peripheral insulin sensitivity did not change after adjustment for dietary fibre and saturated fat intake, body composition, fat oxidation and markers of inflammation. Bacteroidetes/Firmicutes-ratio was not associated with hepatic insulin sensitivity. Men and women differ in microbiota composition and its impact on insulin sensitivity, implying that women might be less sensitive to gut microbiota-induced metabolic aberrations than men. This trial was registered at clinicaltrials.gov as NCT02381145.

Dietary fat, plasma lipoproteins, and immune function in middle-aged American men

Dietary fat has been incriminated as a positive risk factor for the development of neoplasia in human populations. We used adipose tissue fatty acid analysis as an index of dietary fat intake to study the association between dietary fat and immune function in a group of 94 free-living American males (avg age 47 years). Immunocompetence was tested by a battery of T- and B-lymphocyte stimulation tests and also by natural killer (NK) cell activity. Correlations were sought between fatty acid composition, plasma lipids, and immune responsivity. The degree of unsaturation of the diet over a polysaturated-to-saturated fat ratio range of 0.54-1.01 had no predictable effect on the immune function. Stepwise regression analysis showed that the concentrations of plasma triglycerides and cholesterol and its subfractions did not explain any of the variance in the immune tests. Palmitic acid (16:0) was associated with 7% of the variance of the response to C. albicans and E. coli, perhaps through influencing B-cell activity. Stearic acid (18:0) was correlated negatively to concanavalin A responsivity (18% of the variance) and positively to NK activity (20% of the variance). If impaired in vitro immune function is a marker of increased risk for carcinogenesis, then our data do not support a role for dietary fat influencing in any systematic manner lymphocyte function in vitro, as reflected by proliferative response or NK activity. Further, plasma lipoproteins, in particular cholesterol levels, did not appear to affect any immune function test. It remains to be studied whether dietary fat, lipoproteins, or fat-soluble substances may influence membrane structure and function and prostaglandin formation as alternative pathways in the promotion of neoplasia.

Chronic liver disease in abusers of alcohol and parenteral drugs: a report of 204 consecutive biopsy-proven cases

We studied a consecutive series of 204 patients who were admitted to a hospital for addictive diseases during 40 months and who had a liver biopsy. Parenteral drug abusers (n = 34) were significantly younger than alcohol abusers (n = 23) or abusers of both (n = 147) and had lower levels of serum alkaline phosphatase, total bilirubin, and aspartate aminotransferase than the other two groups. Chronic active hepatitis and chronic persistent hepatitis were more frequent (p less than 0.001) in abusers of parenteral drugs alone, whereas cirrhosis was found most often (p less than 0.001) in abusers of both alcohol and parenteral drugs. Cirrhosis was present in 10 of 39 (26%) simultaneous abusers of alcohol and parenteral drugs compared with 58 of 96 (60%) alcohol-abusing former parenteral drug abusers (p less than 0.001). Methadone maintenance treatment was not associated with cirrhosis. Thus, methadone-maintained patients who abuse alcohol and develop cirrhosis should remain in methadone maintenance treatment and receive concomitant alcoholism treatment. Also, these data further support the hypothesis that abusers of both alcohol and parenteral drugs have an increased risk of developing cirrhosis.

The relationship of dietary fat to plasma lipid levels as studied by factor analysis of adipose tissue fatty acid composition in a free-living population of middle-aged American men

We have used adipose tissue biopsies to assess the quality of fat in the diet and its influence on plasma lipid levels in 413 free-living normolipidemic male subjects. Factor analysis identified three factors which separated the fatty acids on the basis of their chemical structure. F1--monounsaturates--animal fats; F2--saturates--carbohydrates; F3--polyunsaturates--vegetable oils. An increase in F1 was associated with an increase in plasma triglycerides (TG), plasma total cholesterol (TC), and VLDL-C: an increase in F2 led to a decrease in VLDL-C. A rise in F3 was associated with lowered TG, VLDL-C, and HDL-C but increased LDL-C. However, the contribution of each of these factors to the variance in TG, TC, LDL-C, and HDL-C was small, namely: 5.48, 1.30, 2.57, and 2.02%, respectively. A special relationship between F3 and VLDL-C was found such that 16.22% of its variance could be attributed to F3. Our conclusion is that adipose tissue composition and, by implication, the type of dietary fat intake, explains only a small proportion (1-19%) of the variance in plasma lipids in normolipidemic subjects.

The role of dietary fat in human obesity

Both the amount and quality of dietary fat have been implicated in the pathogenesis of obesity. Adipose tissue fatty and composition, which is known to reflect dietary intake, was sampled in 413 free-living, healthy American males appearing for a routine medical examination. The average age was 46.8 +/- 11.4 years (mean +/- s.d.) and body mass index (BMI)--weight/height--was 25.2 +/- 3.4. The BMI was correlated (P less than 0.01) with known risk factors for cardiovascular disease as follows: total cholesterol (TC) r = 0.18, triglycerides (TG) r = 0.32, low-density lipoprotein cholesterol (LDL-C) r = 0.18, high-density lipoprotein cholesterol (HDL-C) r = -0.24, systolic and diastolic blood pressure (BP) r = 0.30. Underlying patterns which might be related to diet were sought in the distribution of the seven major fatty acids in adipose tissue. Statistical analysis permitted delineation of three factors which were hypothetically related to animals fat intake (F1--monounsaturates), carbohydrate intake (F2--saturates) and vegetable oil intake (F3--polyunsaturates). F1 and F3 together accounted for 12 percent of the variance in BMI while F2 had no influence. Our conclusions are that the variance in BMI is related much more to non-dietary factors than to adipose tissue fatty acid composition and that the nature of dietary fat was not a major distinguishing factor in obesity in this population. There was also no evidence for a high dietary carbohydrate (low fat) intake in the obese.