An interventional study of Buchinger Fastenbox + intermittent fasting (20-day preoperative schedule) in Hip Osteoarthritis, Arthroplasty, Replacement, Hip and Postoperative Complications, sponsored by Charite University, Berlin, Germany. Recruiting at 1 site in Germany. Open to participants aged 18 Years to 75 Years. Per ClinicalTrials.gov, last updated 2026-06-22.
Sponsored by Charite University, Berlin, Germany · Not applicable, Interventional, and Prevention
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.
Background. Periprosthetic joint infection (PJI) and other postoperative complications after THA carry substantial clinical and economic costs. Recent evidence links the gut microbiome and systemic immune homeostasis to perioperative complication risk, and preoperative caloric restriction has been shown to lower proinflammatory cytokines and shift gut microbial composition toward a less inflammatory profile.
Hypotheses. Primary: A structured 20-day preoperative fasting intervention reduces plasma IL-8 and increases gut microbial alpha-diversity (Shannon index) at Day +7 post-operatively compared with standard preoperative care.
Secondary (exploratory): Fasting modulates broader immune (TNFα, IL-10, immune-cell subsets, activation/exhaustion markers, HLA-DR) and microbiome (taxonomic, functional) parameters, improves metabolic indicators captured by continuous glucose monitoring and daily measures, and reduces postoperative complications, patient-reported infection symptoms, and length of stay.
Design. Single-center, prospective, two-arm, parallel-group, randomized, open-label controlled trial. Randomization is stratified by metabolic status (metabolically healthy vs. metabolically unhealthy per harmonized metabolic-syndrome criteria, Alberti et al. 2009). Planned enrollment: n = 130 (65 per arm; balanced across metabolic strata).
Intervention (Fasting arm). Structured 20-day preoperative fasting schedule self-administered at home with study-team supervision:
Control arm. Standard preoperative care per institutional protocol; no fasting and no probiotic, prebiotic, or symbiotic supplementation as part of the study.
Specimen collection and assessments.
Analyses. Stool: shotgun metagenomic sequencing (Illumina NovaSeq 6000) with bioinformatic processing (Trimmomatic, DIAMOND, QIIME, Centrifuge, MetaPhlAn/HUMAnN, LEfSe). Blood: multiparameter flow cytometry (CD3, CD4, CD8, CD16/56, CD19, plus CD28, CD57, HLA-DR, PD-1) and standard inflammatory chemistry (CRP, IL-6, IL-8, IL-10, TNFα).
Statistics. Two co-primary endpoints (IL-8, alpha-diversity) tested with a fixed-sequence (gatekeeping) procedure: IL-8 first at α=0.05 two-sided; if significant, alpha-diversity is then tested at α=0.05. Linear mixed models or generalized estimating equations are used to model time × group interactions for repeated measures. Microbiome differential abundance: ANCOM/DESeq2 with covariate adjustment (BMI, age, sex). Multiple testing controlled with FDR. Clinical secondary endpoints are analyzed descriptively.
641 studies on the registry are indexed under Osteoarthritis, Hip; 120 are open to participants now.
This study's planned enrollment of 130 is above the median of 90 across 457 interventional studies indexed under Osteoarthritis, Hip.
Browse Osteoarthritis, Hip studies →Charite University, Berlin, Germany is the lead sponsor of 857 studies on the registry; 129 are open to participants now.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Adults aged 18-75 scheduled for elective primary total hip arthroplasty follow a structured 20-day preoperative fasting schedule self-administered at home with study-team supervision. Schedule: Day -20 to -16 - Buchinger Fastenbox (5 days); Day -15 to -11 - intermittent fasting (5 days); Day -10 to -6 - Buchinger Fastenbox (5 days); Day -5 to -1 - intermittent fasting (5 days). No fasting is performed post-operatively. Daily self-monitored ketones, weight, waist circumference, and blood pressure are recorded throughout the fasting window. All other perioperative care follows the standard institutional protocol.
Other: Buchinger Fastenbox + intermittent fasting (20-day preoperative schedule)
Adults aged 18-75 scheduled for elective primary total hip arthroplasty receive routine preoperative care according to the institutional standard at Charité Centrum für Muskuloskeletale Chirurgie. No fasting protocol is provided as part of the study. Continuous glucose monitoring and daily weight, waist circumference, and blood pressure are recorded during the same pre-operative window as the fasting arm. Stool and blood samples are collected at the same study time points as the fasting arm.
Two 5-day cycles of the Buchinger Wilhelmi Fastenbox (hypocaloric, low-carbohydrate, plant-based vegetable broths) alternating with two 5-day cycles of intermittent fasting (time-restricted feeding), totaling 20 days immediately preceding surgery. Self-administered at home; participants receive structured instructions, daily symptom and metabolic logs, and contact options with the study team for the duration of each cycle.
Change in plasma interleukin-8 (IL-8) concentration from baseline to Day +7 post-operatively
IL-8 plasma concentration (pg/mL), measured by validated immunoassay
Time frame: Baseline (Day -21, before start of intervention) and Day +7 post-operatively
Change in gut microbial alpha-diversity (Shannon index) from baseline to Day +7 post-operatively
Shannon diversity index from shotgun-metagenomic stool sequencing
Time frame: Baseline (Day -21, before start of intervention) and Day +7 post-operatively
Perioperative kinetics of plasma cytokines (TNFα, IL-10, IL-6, IL-8)
Serial plasma concentrations of TNFα, IL-10, IL-6, and IL-8 measured by validated immunoassays.
Time frame: Baseline (Day -21), Day -1 pre-op, and 6 h, 24 h, 72 h, and Day +7 post-operatively
Serum C-reactive protein (CRP)
Serum CRP concentration (mg/L).
Time frame: Baseline (Day -21) and Day +7 post-operatively
T-cell subsets (CD3+, CD4+, CD8+) by flow cytometry
Absolute and relative frequencies of CD3+, CD4+, and CD8+ T cells in whole blood.
Time frame: Baseline (Day -21) and Day +7 post-operatively
B-cell frequency (CD19+)
Frequency of CD19+ B cells.
Time frame: Baseline (Day -21) and Day +7 post-operatively
NK-cell frequency (CD16+/CD56+)
Frequency of CD16+/CD56+ natural killer cells.
Time frame: Baseline (Day -21) and Day +7 post-operatively
T-cell activation / exhaustion markers (CD28, CD57, HLA-DR, PD-1)
Frequencies of CD28-, CD57+, HLA-DR+, and PD-1+ T-cell subpopulations.
Time frame: Baseline (Day -21) and Day +7 post-operatively
Monocyte HLA-DR expression (mHLA-DR)
Median fluorescence intensity of HLA-DR on circulating monocytes.
Time frame: Baseline (Day -21) and Day +7 post-operatively
Neutrophil-to-lymphocyte ratio (NLR)
NLR derived from differential blood count.
Time frame: Baseline (Day -21) and Day +7 post-operatively
Gut microbial beta-diversity
Bray-Curtis and weighted UniFrac dissimilarity between time points, analyzed with PERMANOVA.
Time frame: Baseline (Day -21) and Day +7 post-operatively
Differential microbial abundance
Differential abundance of bacterial taxa at genus and species level between arms (ANCOM/DESeq2 with covariate adjustment).
Time frame: Baseline (Day -21) and Day +7 post-operatively
Microbial functional gene profile
Functional gene profiling (HUMAnN) including CAZyme abundance and SCFA-related pathways.
Time frame: Baseline (Day -21) and Day +7 post-operatively
Continuous glucose monitoring (CGM) metrics
Mean interstitial glucose, glucose variability (SD, CV), time-in-range (70-180 mg/dL) derived from a continuous glucose monitor worn from Day -21 until surgery, compared between arms.
Time frame: Day -21 to day of surgery (continuous)
Daily self-monitored ketones (fasting arm)
Daily urinary or capillary ketone measurements during the 20-day fasting window.
Time frame: Day -20 to day of surgery
Daily body weight
Daily self-measured body weight (kg) during the preoperative window, and at follow-up (Week 6, Month 3, Month 6).
Time frame: Day -20 to day of surgery, then Week 6, Month 3, Month 6 post-operatively
Daily waist circumference
Daily self-measured waist circumference (cm) during the preoperative window.
Time frame: Day -20 to day of surgery
Daily blood pressure
Daily self-measured systolic and diastolic blood pressure (mmHg) during the preoperative window.
Time frame: Day -20 to day of surgery
Hip disability and Osteoarthritis Outcome Score (HOOS)
Validated patient-reported hip-specific outcome score; change from baseline to each follow-up time point. HOOS subscale scores range from 0 to 100, with 0 indicating extreme hip symptoms/worst outcome and 100 indicating no hip symptoms/best outcome. Higher scores indicate a better outcome.
Time frame: Baseline (Day -21), Week 6, Month 3, Month 6 post-operatively
Patient-Reported Outcomes Measurement Information System 33-item Profile (PROMIS-33)
Validated multi-domain patient-reported outcomes (PROMIS-33); change from baseline to each follow-up time point. ROMIS-33 is reported as domain-specific T-scores plus a pain intensity item. Domain T-score ranges are: Physical Function 22.5-57.0; Anxiety 40.3-81.6; Depression 41.0-79.4; Fatigue 33.7-75.8; Sleep Disturbance 32.0-73.3; Ability to Participate in Social Roles and Activities 27.5-64.2; Pain Interference 41.6-75.6; Cognitive Function 25.0-61.1. Pain Intensity ranges from 0 to 10. Higher scores indicate a better outcome for Physical Function, Ability to Participate in Social Roles and Activities, and Cognitive Function, and a worse outcome for Anxiety, Depression, Fatigue, Sleep Disturbance, Pain Interference, and Pain Intensity.
Time frame: Baseline (Day -21), Week 6, Month 3, Month 6 post-operatively
Dietary intake (DEGS1 food frequency questionnaire)
Habitual dietary intake captured at baseline using the DEGS1 food-frequency questionnaire.
Time frame: Baseline (Day -21)
Patient-reported postoperative infection symptoms (study-specific questionnaire)
Study-specific questionnaire on infection-relevant signs and symptoms, completed weekly by the patient during the first 6 weeks post-operatively.
Time frame: Weekly from Day +1 to Week 6 post-operatively
Postoperative infectious complications (EBJIS)
Incidence of periprosthetic joint infection per EBJIS criteria within 90 days post-operatively.
Time frame: Day 0 to Day 90 after surgery
Wound healing disorders
Incidence of any wound healing disorder requiring intervention within 90 days post-operatively.
Time frame: Day 0 to Day 90 after surgery
Reoperation rate
Incidence of reoperation related to the index joint within 90 days post-operatively.
Time frame: Day 0 to Day 90 after surgery
Length of hospital stay (LOS)
Length of inpatient stay for the index admission, in days.
Time frame: From day of surgery to day of discharge (assessed up to 30 days)
Metabolic complications
Incidence of postoperative metabolic complications (hyper-/hypoglycemia, electrolyte imbalance, sarcopenia risk markers).
Time frame: Day 0 to Day 30 after surgery
Plan to share: No — Aggregated and de-identified data will be made available through peer-reviewed publications. Individual participant data will not be shared due to data-protection requirements under the Berliner Datenschutzgesetz (BlnDSG) and the EU GDPR.
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