## 4 Discussion
### Implications for Clinical Practice and Health Policy  
The treatment of PIPJ stiffness remains a significant challenge in hand rehabilitation, and for clinical studies in this area to be useful and replicable, it is crucial that clinicians collect data systematically and in a standardized manner. First, the research objectives must be clearly defined, with specific research questions and well-established null and alternative hypotheses. The research question should focus on a key aspect of PIPJ treatment, such as the effectiveness of a specific intervention, and be formulated in a way that allows for a precise evaluation of the intervention under study. Clinicians must measure the ROM of the joint in a standardized way, using validated measurement tools such as digital goniometers or 2D or 3D analysis systems, ensuring that the same techniques are consistently used for each patient. Furthermore, it is necessary to record the standard deviation of measurements to accurately assess the variability of the data. The treatment should follow standardized protocols that clinicians can replicate consistently. This includes specifying the type of intervention (e.g., orthoses, PIPJ manipulation, etc. ), its frequency, duration, and intensity, and ensuring that the same criteria apply to all patients. The intervention must be clearly documented to guarantee that it can be replicated in future studies or other clinical settings. Additionally, it is crucial to limit co-interventions or carefully record any other treatments the patients may be receiving to avoid interference with the results. It is essential that studies not only focus on clinical data but also include patient-centered outcomes, such as QoL, pain reduction, and functional improvements. These data provide a comprehensive picture of how treatment impacts the daily lives of patients. To achieve this, clinicians should use standardized questionnaires that measure these outcomes, such as DASH or QuickDASH, which capture the patient's subjective experience regarding their function and well-being. Long-term follow-up is essential to assess whether the effects of treatment are sustainable. Clinicians should perform ROM measurements and other outcomes at regular intervals, such as 1, 3, 6, and 12 months, to assess the patient's progress and whether PIPJ stiffness recurs after treatment. It is important that all measurements are taken under similar conditions to ensure the reliability and consistency of the data. Additionally, clinicians must record all aspects of the patient's progress in detail. This includes not only ROM measurements but also the patient's progress in terms of functionality, pain level, and any changes in treatment or symptoms. This information provides context and helps interpret the results more accurately. One of the major issues identified in previous studies is the lack of standardized protocols to prevent the recurrence of stiffness after treatment. Clinicians should implement clear and documented preventive strategies that include recommendations for the use of orthoses, exercise, and other interventions to reduce the risk of stiffness reoccurrence. Since each patient may respond differently to interventions, it is important for clinicians to follow a personalized approach. Protocols should allow for adaptations based on the patient's response to treatment. This includes adjustments to the intensity or duration of interventions depending on the ROM evolution and the patient's tolerance. Clinicians should document these changes and make dynamic adjustments to the treatment plan as needed. It is essential that clinicians and researchers work closely in data collection, ensuring that all values and measurements are reported consistently and in detail. This includes ensuring that the data are accessible for subsequent analysis, which will facilitate the interpretation of the results.