The development of patient-specific medical systems poses challenges for requirements engineering and their traceable integration into system models, as regulatory frameworks require transparent and traceable links between stakeholder needs and product requirements. Document-based approaches lack the formal structure required to derive verifiable product requirements and integrate patient-individual parameters into testing processes. This study investigates how Model-Based Systems Engineering (MBSE) can formalize user needs, user requirements, and patient context parameters to enable a traceable, model-based testing of patient-specific systems. A SysML-based formalization approach is developed that extends the motego method. New stereotypes for user needs and user requirements are introduced and linked via SysML relations to stakeholders, use scenarios, and product requirements. A patient context model is proposed to represent patient-individual parameters and integrate them into a model-based test framework. The approach is demonstrated using an exemplary use case by instantiating representative user needs, user requirements, and patient context parameters and linking them to functions, solutions, and domain model elements within the test framework. An exemplary use case demonstrates the integration and transfer of context parameters. The results show a traceable chain between stakeholders and product requirements, as well as the consistent transfer of context parameters into domain model elements. The simulation is used exclusively as an executable component to demonstrate data integration and model consistency; no validation of physical accuracy is performed.