Understanding elbow joint loads after total elbow arthroplasty

A total elbow arthroplasty (TEA) helps people with severe elbow problems regain functional use of their arm. However, such a prosthesis does not last a lifetime. Overloading is a key cause of long-term wear, while current recommendations – such as “do not lift more than 1 kilogram” – are barely supported by biomechanical evidence. This dissertation uses musculoskeletal models to investigate elbow joint load during everyday activities. It examines the joint moments acting on the elbow and the ulnohumeral joint reaction forces: the forces between the humerus and the ulna. The results show that the 1-kg lifting restriction does not reduce elbow loading. In fact, it was not lifting 1 kilogram, but rather more complex pushing and pulling tasks – such as opening a door – that generated the highest loads. Additionally, it appeared that not the flexion–extension direction (bending and straightening) but the varus–valgus direction was most critical: the sideways forces on the joint. This can be likened to a door designed to open and close normally, but suddenly being pushed sideways; the hinge experiences stress in a direction it was not designed for. These findings indicate that current postoperative guidelines, which focus on limiting lifting weight, do not adequately reflect the actual loads experienced during daily activities. Shoulder elevation and full elbow extension, in particular, were found to increase joint loading and may need to be limited during early rehabilitation. The insights from this research can support the development of more task-specific, biomechanically grounded advice and contribute to more durable prosthesis designs in the future.