Background: Thumb carpometacarpal joint (CMC) osteoarthritis is the most symptomatic hand arthritis but the long-term healthcare burden for managing this condition is unknown. We sought to compare total healthcare cost and utilisation for operative and nonoperative treatments of thumb CMC arthritis. Methods: We conducted a retrospective longitudinal analysis using a large nationwide insurance claims database. A total of 18,705 patients underwent CMC arthroplasty (trapeziectomy with or without ligament reconstruction tendon interposition) or steroid injections between 1 October 2015 and 31 December 2018. Primary outcomes, healthcare utilisation and costs were measured from 1 year pre-intervention to 3 years post-intervention. Generalised linear mixed effect models adjusted for potentially confounding factors such as the Elixhauser comorbidity score with propensity score matching were applied to evaluate the association between the primary outcomes and treatment type. Results: A total of 13,646 patients underwent treatment through steroid injections, and 5,059 patients underwent CMC arthroplasty. At 1 year preoperatively, the surgery group required $635 more healthcare costs (95% CI [594.28, 675.27]; p < 0.001) and consumed 42% more healthcare utilisation (95% CI [1.38, 1.46]; p < 0.0001) than the steroid injection group. At 3 years postoperatively, the surgery group required $846 less healthcare costs (95% CI [-883.07, -808.51], p < 0.0001) and had 51% less utilisation (95% CI [0.49, 0.53]; p < 0.0001) annually. Cumulatively over 3 years, the surgical group on average was $4,204 costlier than its counterpart secondary to surgical costs. Conclusions: CMC arthritis treatment incurs high healthcare cost and utilisation independent of other medical comorbidities. At 3 years postoperatively, the annual healthcare cost and utilisation for surgical patients were less than those for patients who underwent conservative management, but this difference was insufficient to offset the initial surgical cost. Level of Evidence: Level III (Therapeutic).