Surgery for Thumb Base Osteoarthritis: Joint Replacement vs. Trapeziectomy (BASTION)

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.