The Aim of This Study is to Assess the Feasibility of the Study Protocol and the Acceptability of the Mobile Application-Based Intervention. The Results Will Guide the Design and Evaluation of a Definitive, Larger-scale Study to Further Examine the Efficacy of the Refined Intervention.

This study is a pilot study for a larger future research project aimed at examining the effects of patient education delivered via a mobile application on patients' self-reported receipt of information in relation to their information needs, as well as on patient-reported quality of life, pain, and functional capacity, compared with traditional patient education provided during in-person appointments or by telephone. The primary objective of this pilot study is to assess the feasibility of conducting the forthcoming larger-scale study. Research questions: 1. How does patient education delivered via a mobile application meet the information needs of patients undergoing joint replacement surgery, and is the intervention feasible to implement in a larger research setting? 2. How do the instruments used in the pilot study (EKhp/RKhp, EQ-5D-5L, NRS, and OKS/OHS) and the study design function when delivered via a mobile application for the intervention group and in conjunction with traditional patient education for the control group, and are the instruments and study design suitable for conducting a larger-scale study. The study will be conducted as a randomized controlled trial (RCT). Patients will be allocated into two groups: Intervention group: receives patient education via a mobile application. Control group: receives traditional patient education during face-to-face clinic visits or by telephone. Data will be collected using questionnaires before surgery (three measurement points) and after surgery (two measurement points).

Inclusion Criteria: * Primary knee or hip joint replacement surgery * No previous visits to Coxa * Age 18-75 years * Proficiency in the Finnish language * Body mass index (BMI) below 40 * Moderate alcohol consumption (AUDIT \< 20) * Ability to use a mobile application (access to a compatible smartphone) * The patient may have a mild systemic disease that does not significantly limit functional capacity (ASA I-II) * The patient may also have a somewhat more severe condition, provided that underlying diseases are well controlled (ASA III) * Medication use is moderate, consisting of 1-5 medications in addition to pain medication * No use of anticoagulant medication * No previously identified anesthetic complications Exclusion Criteria: * Previous joint surgery * Functional impairment / disability * Insufficient proficiency in the Finnish language * No possibility to use a mobile application (no mobile phone) * Patient with multiple comorbidities (multimorbid patient) * The patient does not proceed to the surgical waiting list