Trial purpose is to research the outcome after thumb carpometacarpal injection with stromal vascular fraction (SVF) derived from adipose tissue. The study compares SVF injection therapy with thumb splinting vs. splinting only.

Patients with radiologically and clinically confirmed Eaton-Glickel II osteoarthritis are randomized (1:1 computer generated sequence with random block size) to two parallel groups and will undergo SVF injection and splinting vs. splinting only.

Baseline data is collected preoperatively and patients are followed at 1, 3 and 6 months after enrollment. The primary end-point is 6 months and the primary outcome is pain visual analogue scale and patient-rated wrist evaluation (PRWE).

Inclusion Criteria:

• Age 40-70 years
• Eaton-Glickel II thumb CMC osteoarthrosis
• Symptom duration > 3 months
• Pain visual analogue score > 30 mm
• < 3 months of treatment with thumb splinting
• American Society of Anaesthesiologists physical status (ASA) I-III
• Fluent in written and spoken Finnish

Exclusion Criteria:

• Age <40 or >70 years
• Eaton-Glickel I, III-IV
• Symptom duration < 3 months
• Pain VAS < 30 mm
• Post-traumatic osteoarthrosis of thumb CMC I
• Rheumatoid arthritis or other inflammatory joint disease
• The use of per oral corticosteroids or other immunomodulatory drugs
• Less than 6 months after another operation of the same upper limb
• Other condition of the same upper limb requiring surgery
• Malnutrition
• Neurological condition affecting upper limb function
• Heavy smoking (> 20 cigarettes per day)
• Alcohol or drug abuse
• Previous history or active cancer
• Previous history of allergic reaction to local anaesthetic