A Review of the Methodology in Studies on the Treatment of the Proximal Interphalangeal Joint to Analyze Homogeneity and Detect Inconsistencies

Background/Objectives: The treatment of proximal interphalangeal joint stiffness is challenging due to methodological inconsistencies in existing studies. While many studies report range of motion improvements, their limitations raise concerns about result reliability. This review examines whether studies follow standardized protocols or present inconsistencies that hinder evidence-based clinical recommendations. Methods: A systematic review was conducted following PRISMA 2020 guidelines. A literature search in PubMed, Cochrane, PEDro, and ScienceDirect included randomized controlled trials, observational studies, case reports, and systematic reviews. Study quality was assessed based on design, blinding, data collection, and reporting consistency, focusing on standardized range of motion measurements. Results: Most studies showed significant methodological deficiencies, including a lack of controls, inconsistent outcome measures, small samples, and failure to report essential data such as baseline and final range of motion values with standard deviations. These inconsistencies prevented determination of whether reported improvements were treatment-induced or influenced by external factors. Conclusions: Greater methodological rigor is needed in research on the proximal interphalangeal joint. Without standardized protocols, rigorous data collection, and proper controls, treatment effectiveness cannot be reliably assessed. Future studies must ensure methodological consistency to generate evidence-based recommendations.