Features of Biomechanics and Rehabilitation of the Shoulder Joint after Reverse Arthroplasty: а Review

Reverse shoulder arthroplasty is one of the methods used to treat shoulder joint diseases. The indications for this type of surgery are as follows: clinically expressed arthrosis, including defect arthropathy, rheumatoid arthritis, fracture–dislocation and fractures of the humeral head, oncopathology of the shoulder joint, avascular necrosis, massive rotator cuff tear and dysfunction of the previously installed prosthesis. To date, various models of reverse endoprostheses based on the principles of P. Grammont are used in clinical practice. Shoulder joint arthroplasty is now being used more and more frequently worldwide. The number of shoulder joint replacement surgeries is expected to increase by more than 200% by 2025. One of the features of reverse arthroplasty is the change of the polarity of the articular surfaces. The design of the prosthetic implant significantly changes the biomechanics of the shoulder joint. Different variations of the design parameters affect the functioning of the joint. In order to achieve optimal volume of movement, it is necessary to carefully select the following characteristics of the implant: the diameter of the glenoidal sphere, the displacement of the scapular component, the displacement of the rotation center and the change in the angle of inclination of the neck of the shoulder component.Understanding the biomechanical features of the shoulder joint after reverse endoprosthetics makes it possible to determine the optimal approach to the rehabilitation treatment of patients after surgery. The main goals of rehabilitation after reverse arthroplasty are: pain minimization and ensuring the healing of postoperative wounds, prevention of postoperative complications (dislocations and periprosthetic fractures), gradual progress of the shoulder motion range, increasing the strength and endurance of the muscles of the shoulder girdle, especially the deltoid muscle. Despite the existence of standard protocols, there are differences in many issues related to postoperative management of patients. This topic needs further development.