A Phase 2 interventional study of Vitamin C and Placebo in Chronic Pain, Knee Pain Chronic and Post Operative Pain, sponsored by University Health Network, Toronto. Recruiting at 3 sites in Canada. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-06-23.
Sponsored by University Health Network, Toronto · Phase 2, Interventional, and Prevention
Phase II Multicentre, pilot, parallel-group, blinded, 1:1 randomized controlled trial to determine the feasibility of conducting a larger definitive trail of using vitamin C to reduce persistent pain in patients undergoing total knee arthroplasty surgery.
PROVISION is a multicentre, pilot, parallel-group, blinded, randomized controlled trial of 400 patients undergoing total knee arthroplasty surgery. Consented eligible patients will be randomized to receive vitamin C: 2000 mg taken orally within 4 hours of the start of surgery, followed by 500 mg of vitamin C taken twice daily from post-operative day 1 to day 56 (8 weeks). Patient in the control group will receive placebo lactose monohydrate capsules. Study medications will be prepared to look similar and labelled as per regulatory requirements. Patients will follow up on post-operative days 1-3, weeks 2,4,6, and 8 post-operatively, and at 3- and 12-months post-operatively to report on pain, opioid and analgesic consumption, medication adherence, adverse events, functional, mood, and quality of life outcomes.
2,930 studies on the registry are indexed under Chronic Pain; 701 are open to participants now.
This study's planned enrollment of 400 is above the median of 60 across 2,161 interventional studies indexed under Chronic Pain.
Browse Chronic Pain studies →University Health Network, Toronto is the lead sponsor of 1,411 studies on the registry; 292 are open to participants now.
Of its 17 completed or terminated interventional studies of FDA-regulated products, 3 (18%) have results posted.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
Preoperative Vitamin C capsules
Drug: Vitamin C
Preoperative placebo capsules
Drug: Placebo
Drug: Patients in the intervention group will receive 2g Vitamin C orally within 4 hours of the start of the surgery followed by 500 mg of Vitamin C to be taken orally twice a day from post-op day1 to day 56.
Also known as: Ascorbic Acid
Drug: Patients in the placebo group will receive identical placebo capsules taken orally within 4 hours of the start of the surgery followed by placebo capsules taken orally twice a day from post-op day 1 to day 56.
Also known as: Lactose (Monohydrate)
Study will determine feasibility of enrolling, recruiting, and follow-up with patients.
The study will assess the feasibility of enrolling, recruiting, and following-up with patients undergoing a primary total knee arthroplasty (TKA) through active monitoring of recruitment/enrollment rates on a monthly basis for a total of one year using excel trackers. The follow-up rate of patients will be assessed at 12 months based on completion of all 12 month questionnaires.
Time frame: 12 months
Clinical site compliance
Clinical site compliance with trial protocol will be determined based on number of protocol deviations at each site as logged on the deviation logs. This will be assessed on a monthly basis for a full year to maintain active monitoring of compliance.
Time frame: 12 months
Resource Assessment
This pilot study will help determine the resources required for larger definitive trial based on critical analysis of recruitment trackers to assess time spent on recruitment/enrollment.
Time frame: 12 months
Prevalence of persistent pain
Pain intensity measured using 0-10 Numeric Rating Scale (NRS) scale at rest and movement
Time frame: 3 months and 12 months
Qualities and characteristics of persistent pain
Pain qualities measured using the 0-10 scale of the Short Form McGill Pain Questionnaire 2 (SF-MPQ-2)
Time frame: 3 months and 12 months
Persistent Neuropathic Pain
Neuropathic pain assessed on a binary scale of Yes or No using the Douleur Neuropathique 4 (DN4) symptoms interview
Time frame: 3 months and 12 months
Acute and chronic analgesic consumption
Analgesic and oral morphine-equivalent opioid consumption
Time frame: Day of surgery, post-operative day 1-3, 3 months, and 12 months
Development of Complex Regional Pain Syndrome (CRPS)
Presence of CRPS measured by a physical assessment of sensory, vasomotor, sudomotor/edema, and motor/tropic categories using the Budapest Criteria
Time frame: 3 months and 12 months
Physical function
Patient reported outcome measure to assess level of function, daily living activities and their affect on pain measured by answering 12 questions using the Oxford Knee Score (OKS)
Time frame: 3 months and 12 months
Emotional functioning
Patients emotional functioning measured on a scale of 1-5 using the EQ-5D-5L
Time frame: 3 months and 12 months
Patient Satisfaction
Assessment of patient satisfaction with surgery on scale of 0-100
Time frame: 3 months and 12 months
Quality of life assessment
Patient reported assessment of mobility, self-care, usual activities, pain/discomfort, and anxiety/depression on a scale of level 1 - level 5 using the EuroQol 5-dimension 5-level (EQ-5D-5L)
Time frame: 3 months and 12 months
Adverse events
Monitored as a secondary safety outcome using an assessment of follow-up visits for drug related adverse events and passive surveillance of clinical notes
Time frame: 3 months and 12 months
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University Health Network, Toronto