The impact of thumb carpometacarpal osteoarthritis and the effectiveness of splinting

Abstract

Background: Thumb carpometacarpal (CMC) osteoarthritis (OA) is a common, disabling condition, affecting substantial numbers of working and older-age people. It is the single commonest site affected by OA yet its unique characteristics, distinct from general hand OA, have received little individual attention – far less than hip and knee OA. In particular, little is known from patients’ perspectives about the impact of thumb CMC OA. Furthermore, international guidelines recommend splinting as a non-surgical, non- pharmacological treatment option for CMC OA; however, evidence supporting splinting in people with thumb CMC OA is sparse and inconsistent. The aims of this research were to: 1) explore the impact of thumb CMC OA from the perspective of people living with the condition; 2) investigate the effectiveness of splinting interventions for thumb CMC OA. Methods: Three main studies were conducted: 1) a pragmatic qualitative study exploring the impact of thumb CMC OA in 30 individual interviews of people with the condition; 2) a systematic review with meta-analyses of previous studies reporting on the effectiveness of splinting for thumb CMC OA; 3) a feasibility study for a future fully-powered randomised controlled trial (RCT) investigating the effectiveness of a soft splint intervention combined with standardised best practice usual care vs best practice usual care alone comparator intervention. Design of the feasibility study was based on the findings from the qualitative study and the systematic review. Results: The qualitative study identified five main themes representing five inter-related levels of health impact: negative experience of symptoms, functional limitations, restricted social activities and roles, negative thoughts and feelings, and altered sense of self. Pain, including pain at night, was the major concern. CMC OA impact was influenced by: dominant hand involvement; cold climate; people’s financial, social, and societal support; and attitudes to the condition. Many areas of impact are unidentified and missing in currently recommended patient-reported outcomes. The study found a strong desire for access to high-quality information about self-management and effective non-surgical, non-pharmacological treatment options. All evidence for splinting was of low quality. Splints cause a moderate-to-large reduction in pain (SMD -0.7 [95% CI -1.04, -0.35], < 0.0001) and small-to-moderate improvement in function (SMD -0.42 [-0.77, -0.08], p = 0.02) in the medium-term (3-12 months). No effect exists in the short-term. The review identified: variability in self-reported outcomes, case definitions, and rationale for splinting; low and variable splint dosage; lack of standardised usual care; unassessed QoL; and inappropriate study designs. In the feasibility study, all primary outcomes surpassed the a priori thresholds for feasibility. Of thirty enrolled participants, 29 (97%) were retained at the 4-week and 6-month follow-ups. Interventions were acceptable and safe. Preliminary clinical findings suggested greater improvements in pain in the splint group vs comparator intervention in the short-term. Conclusions: Thumb CMC OA has a profound impact on a person’s health and well-being. Splinting is an acceptable and promising intervention although good quality evidence to support its use is lacking. A full RCT of splinting in addition to standardised best practice usual care for thumb CMC OA pain is feasible but should be preceded by exploration of dose effect and optimisation of outcome measures.