Trapeziometacarpal Joint Arthroplasty Versus Trapeziectomy for Thumb Carpometacarpal Osteoarthritis

Aim and objectives The primary aim is to compare early postoperative pain trajectories after CMC-1 arthroplasty versus trapeziectomy for symptomatic thumb carpometacarpal osteoarthritis, using day-by-day patient-reported pain measurements during the first 90 postoperative days.

Secondary aims are to compare:

(i) Daily analgesic consumption during the first 90 postoperative days (ii) Orthosis use after cast removal (iii) Patient-reported hand/upper limb function using HQ-8, QuickDASH and Nelson score (iv) Blinded clinical measures of thumb range of motion, grip strength and pinch strength (v) Long-term clinical outcomes up to 10 years. Additionally, in the arthroplasty group, a long-term aim is to evaluate migration and radiological signs of implant loosening using cone beam computed tomography (CBCT). Similarly, in the trapeziectomy group, CBCT will be used to monitor and quantify metacarpal 1 proximal migration.

This protocol has been prepared in accordance with SPIRIT 2025 guidance \[18\], and includes a PRO EDI participant characteristics (Table 1).

Trial design This is a single-centre, assessor-blinded randomised controlled trial (RCT) with 1:1 allocation to prosthetic CMC-1 arthroplasty or trapeziectomy.

Study setting The study will be conducted at the Hand Surgery Clinic, Sahlgrenska University Hospital, Gothenburg, Sweden. All operations will be performed by surgeons experienced in both techniques at least level 3 according to Giddins-Tang classification \[19\] and have at minimum overcome the previously described learning curve thresholds \[20,21\].

Eligibility criteria

Inclusion criteria:

* Pain at the base of the thumb affecting activities of daily living and insufficient response to at least 3 months of non-operative treatment (orthosis, non-steroidal anti-inflammatory drugs, and/or corticosteroid injections). * Radiographic thumb carpometacarpal osteoarthritis, Eaton grade 2-4. * For Eaton grade 2, age ≥50 years. * Age 18-69 years. * Provision of written informed consent.

Exclusion criteria:

* Symptomatic osteoarthritis of adjacent joints (e.g., scaphotrapeziotrapezoid joint, STT-joint). * Need for concurrent surgery in the metacarpophalangeal joint (e.g. arthrodesis or capsulodesis). * Post-traumatic thumb carpometacarpal osteoarthritis. * Previous surgery for thumb carpometacarpal osteoarthritis in the contralateral hand. * Inflammatory arthritis (e.g., rheumatoid arthritis or systemic lupus erythematosus). * Osteoporosis/osteopenia of such severity that secure cup placement in the trapezium is not possible (for arthroplasty). * Ongoing systemic corticosteroid treatment. * Other hand surgical condition in the same hand that could confound outcomes (e.g., carpal tunnel syndrome or de Quervain tenosynovitis). * Cognitive impairment preventing reliable participation. * Ongoing, or suspected ongoing, alcohol or drug misuse. * Insufficient Swedish language proficiency to complete the questionnaires.

Participant identification, recruitment and consent Potential participants will be identified among patients referred for surgical evaluation of symptomatic thumb carpometacarpal osteoarthritis at the study site. Eligible patients will receive verbal and written information about the study. Written informed consent will be obtained before any study-specific data collection.

At baseline, participants will complete the HQ-8, QuickDASH and Nelson score questionnaires. Baseline demographic characteristics will be recorded in line with the PRO

• Analgesics used [Time frame: daily for three months]
• Use of Orthosis [Time frame: Daily for three months]
• Patient-reported thumb symptoms [Time frame: at 30, 45, 60, 75 and 90 postoperative days]
• Patient-reported upper extremity function [Time frame: at 30, 45, 60, 75 and 90 postoperative days]
• Patient-reported hand function [Time frame: at 30, 45, 60, 75 and 90 postoperative days]
• Range of motion [Time frame: at 45 and 90 postoperative days and at 6 months and 1, 2, 5 and 10 years.]
• Strength [Time frame: at 45 and 90 postoperative days and at 6 months and 1, 2, 5 and 10 years.]
• Migration of prosthesis on cone beam computed tomography [Time frame: at 6 months and 1, 2, 5 and 10 years (with a 1-week reference scan).]