INTRODUCTION: Knee osteoarthritis often starts in the patellofemoral compartment of the knee and is diagnosed in about 39% of people with knee pain aged above 30 years. Patellofemoral osteoarthritis plays a crucial role in the reduction of quality of life and in the rise of healthcare costs. There is still no consensus for treatment recommendation for isolated patella-femoral osteoarthritis in clinical guidelines. Current therapeutic approaches are limited to pain management, alleviation of symptoms or total knee replacement. Nasal chondrocyte tissue-engineered cartilage (N-TEC) has already been successfully introduced in clinical studies phase I and II for the treatment of focal cartilage lesions and in pilot studies in osteoarthritis patients. METHODS AND ANALYSIS: A randomised controlled trial involving 75 patients with patellofemoral osteoarthritis from nine different clinical centres in Switzerland, Germany and Croatia is being conducted to evaluate the effectiveness of N-TEC implantation compared with standard treatment with platelet-rich plasma (PRP). In the intervention group, an autologous nasal cartilage cell-derived graft is implanted into the cartilage defects of the patella and/or trochlea during an open surgical procedure. The control group receives three PRP injections at weekly intervals. The primary outcome is the mean Knee Injury and Osteoarthritis Outcome Score Pain Change from baseline to 24 months between groups. Secondary outcomes, including patients' self-assessed questionnaires, X-ray and MRI scans, physiotherapeutic assessments and safety, will be assessed and compared between the intervention and control group. In addition, the study is complemented with a health-economic evaluation to establish the intervention's value for money and impact on productivity in working-age individuals. The planned duration of the study is 4 years including baseline and follow-up measurements at 6, 12 and 24 months. ETHICS AND DISSEMINATION: All centres involved in the implementation of the intervention have obtained approval from their respective competent ethics committees. This includes approval from the following ethics committees: Ethics Committees of North-Western and Central Switzerland (EKNZ): 2024-00075 (associated ethical committees: Cantonal Ethics Committee Bern, Cantonal Research Ethics Commission Geneva (CCER), Cantonal Ethics Committee Ticino, Cantonal Ethics Committee Zurich). The EKNZ covers several cantons in Switzerland, including Basel. The site in Lugano falls under the Cantonal Ethics Committee Ticino. Ethics Germany according to CTIS: 2023-508640-21-00 (Medicinal Ethical Commission of the Julius-Maximilians-University Wuerzburg, Ethical Commission of the Albert-Ludwigs-University Freiburg) and Central Ethical Committee Croatia, Republic of Croatia Ministry of Health: 2023-508640-21-00. The Swissmedic reference number is 701788.Prior to participation, all participants must have signed informed consent. Study information will be disseminated via hospital websites, newsletters and an open-access publication of the protocol. Results will be published in peer-reviewed journals, presented at national and international conferences and shared with the public. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registration No.: NCT06163573; Registration number CTIS: 2023-508640-21-00.