Aim: to develop a score for assessing the state of the knee joint (KJ) after the total knee arthroplasty (TKA). Materials and methods. Patients were examined before treatment, before the patient was discharged from the clinic, and during follow-up examinations after 3, 6, 12 months, and annually thereafter. For the clinical evaluation of the KJ after TKA, we used the algofunctional Leken index. Patients underwent X-ray, X-ray densitometric and ultrasound examination with dynamic functional testing (forced bending in the KJ). Results. A scoring system for the operated KJ was developed. For the first time, the data of X-ray, densitometric and ultrasound examination were used to diagnose early instability of KJ endoprosthesis components. Conclusion. Implementation of the developed score will improve diagnosis, prevent the development of postoperative complications, and increase the effectiveness of treatment of patients after TKA.