Surgery for Thumb Base Osteoarthritis: Joint Replacement vs. Trapeziectomy

BASTION - BASe of Thumb Osteoarthritis Management Non-inferiority Trial: Surgical Treatment of First Carpometacarpal Joint Osteoarthritis: A Comparison Between Joint Replacement and Trapeziectomy

The goal of this clinical trial is to learn if the surgical method with total joint arthroplasty, (TOUCH joint prosthesis), is as good as or better than the traditional surgical method, trapezectomy, to treat thumb base joint osteoarthritis.

The main questions it aims to answer are:

Does surgery with total joint arthroplasty provide better power grip and pinch grip strength compared to traditional surgery?

What is the long-term risk of complications for both methods?

Which method is more cost-effective for the healthcare system?

Researchers will compare total joint arthroplasty (TOUCH) to trapezectomy (a procedure where a bone in the thumb base is removed) to see which method provides the best results for the patient.

Participants will:

Be randomized to undergo either an operation with total joint arthroplasty or a trapezectomy.

Undergo an initial evaluation and a health economic cost analysis after one year.

Attend follow-up checkups at 2, 5, and 10 years post-surgery to evaluate long-term function and the durability of the prosthesis.

Background and Rationale:

Basal joint arthritis of the thumb (trapeziometacarpal osteoarthritis) is a common condition causing pain and reduced hand function. While trapeziectomy with ligament reconstruction/capsuloplasty has long been a gold standard, total joint arthroplasty, such as the TOUCH prosthesis, has gained popularity. However, there is a lack of high-quality prospective randomized controlled trials (RCTs) comparing these methods regarding long-term functional outcomes, complication rates, and cost-effectiveness. This study aims to compare the clinical and health-economic outcomes of total joint arthroplasty with TOUCH prosthesis versus trapeziectomy with capsuloplasty.

Study Design and Randomization:

This is a prospective, randomized controlled trial. Following informed consent obtained by the attending surgeon, participants are randomized to either:

1. Total joint arthroplasty using the TOUCH prosthesis.
2. Trapeziectomy with capsuloplasty. Randomization is performed in close proximity to the day of surgery. Due to the nature of the interventions, participants are informed of the surgical method postoperatively.

Procedures and Follow-up

• Surgical Intervention: Both procedures are performed according to standardized institutional protocols.
• Postoperative Care (Trapeziectomy): The thumb is immobilized in a cast for 3 weeks, followed by a standardized rehabilitation program led by occupational and physical therapists.
• Postoperative Care (total joint arthroplasty): A stable soft dressing is applied for 3 weeks, followed by the same rehabilitation protocol.
• Follow-up Schedule: Participants are evaluated at 3 weeks, 6 weeks, 12 weeks, 12 months, 24 months, 5 years, and 10 years postoperatively.
• Imaging: Radiographic evaluations are performed for the prosthesis group at 6 weeks, 12 months, 24 months, 5 years, and 10 years to monitor for prosthesis loosening or "z-deformity" (MCP joint hyperextension) compared to the trapeziectomy group.

Data Management and Quality Assurance:

Data is collected and managed using REDCap (Research Electronic Data Capture) to ensure data integrity and validation. Physical informed consent forms are stored securely at the Department of Hand Surgery. Source data verification is performed by comparing registry data against electronic medical records and paper-based Case Report Forms (CRFs).

Sample Size and Power Calculation:

The primary outcome is Jamar grip strength at 12 months. Based on a Minimal Clinically Important Difference (MCID) of 6.5 kg and a standard deviation (SD) of 8.5 kg (derived from existing literature and pilot data), a power calculation (90% power, alpha 0.05, two-sided t-test) determined a requirement of 37 patients per group. To account for a 10% dropout rate, the total cohort size is set at 84 patients (42 per arm).

Health Economic Analysis:

A comprehensive health economic evaluation will be conducted to compare the total costs of both methods. This analysis includes:

• Direct Costs: Implant costs, anesthesia, surgical time, and healthcare utilization (number of visits).
• Indirect Costs: Duration of sick leave and time to return to work.
• Secondary Metrics: Analgesic consumption (paracetamol and opioids), patient-reported quality of life (EQ-5D), and "pain-free days" based on NRS (Numerical Rating Scale) assessments.

The objective is to determine if the higher initial cost of the TOUCH prosthesis is offset by faster recovery, reduced sick leave, and improved long-term productivity.

Inclusion Criteria:

• Age 40-80 years at inclusion
• CMC-joint osteoarthritis grade 1-3 (Eaton-Littler classification)
• Rest pain or pain reducing hand function with indication for surgery
• Insufficient relief from non-operative treatment for ≥3 months (orthosis, OTC analgesics, cortisone injection)
• Eligible for both prosthesis and trapezectomy per including surgeon
• Non-smoker or complete smoking cessation ≥6 weeks prior to surgery

Exclusion Criteria:

• Previous surgery to thumb base or STT-joint
• Ongoing chronic pain condition
• Dementia or cognitive impairment
• Trapezium height <7 mm on plain radiograph
• Active smoker
• Osteoarthritis grade 4 (Eaton-Littler)