Preoperative Fasting and the Gut Microbiome Before Hip Replacement

Summary

Postoperative complications occur in 5-15% of patients undergoing elective primary total hip arthroplasty (THA), including periprosthetic joint infection (PJI), thrombosis, wound healing disorders, and metabolic dysregulation. The gut microbiome and the systemic immune profile have both been implicated as modifiable contributors to perioperative complication risk. Preoperative therapeutic fasting has been shown to remodel the gut microbiome, lower proinflammatory cytokines, and improve metabolic parameters. This single-center, prospective, randomized, two-arm controlled trial at Charité - Universitätsmedizin Berlin investigates whether a structured 20-day preoperative fasting intervention (alternating cycles of the Buchinger Fastenbox and intermittent fasting) modulates two co-primary endpoints - plasma IL-8 (a central proinflammatory marker) and gut microbial alpha-diversity (Shannon index) - compared with standard preoperative care. Secondary endpoints include further immune markers (TNFα, IL-10, T-/B-/NK-cell subsets, activation/exhaustion markers, monocyte HLA-DR), microbiome composition and function, continuous glucose-monitoring and daily metabolic measures, patient-reported outcomes (HOOS, PROMIS-33, infection self-report), and clinical outcomes (postoperative complications per EBJIS criteria, length of stay). Adults aged 18-75 undergoing elective primary THA are stratified by metabolic status (metabolically healthy vs. metabolically unhealthy according to harmonized metabolic-syndrome criteria) and randomized 1:1 to the fasting intervention versus standard care. Stool and whole-blood samples are collected at baseline (Day -21), and at Day +7 post-operatively for shotgun-metagenomic sequencing and multiparameter flow cytometry, with additional cytokine blood samples at Day -1 and 6 h / 24 h / 72 h post-operatively. Continuous glucose monitoring is performed in all participants from Day -21 until surgery. Planned enrollment is 130 participants.

Eligibility

Inclusion Criteria:

* Adults aged 18-75 years (inclusive)
* Scheduled for elective primary total hip arthroplasty (THA)
* Able and willing to provide written informed consent
* Able to follow the 20-day preoperative fasting protocol independently at home (if randomized to the fasting arm) or willing to be randomized to either arm

Exclusion Criteria:

* Resorption disorder due to bowel disease (e.g. inflammatory bowel disease, short-bowel syndrome, active celiac disease)
* Antibiotic therapy within the last 2 months before baseline (T0)
* Probiotic, prebiotic, or symbiotic supplementation within the last 2 months before baseline (T0)
* Inability or unwillingness to provide informed consent
* Severe comorbidity precluding fasting (e.g. ASA ≥ IV, advanced renal/hepatic impairment, eating disorder)
* BMI \< 18.5 kg/m² (underweight)
* Concurrent participation in another interventional drug or device trial
* Pregnancy or breastfeeding

Conditions6

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