Postoperative rehabilitation and mobilisation generally begins on the first day after surgery. Here, the ability to perform weight-bearing activities depends upon the initial stability of the implant: whilst a cemented implant allows full weight-bearing activity from the first post-operative day onwards, uncemented implants require the patient to weight-bear only partially for a period of 3 months in order to ensure osseointegration of the implant. Loads of 200-300% times bodyweight have been shown to cause micromotion of >150 µm between the implant and bone, which might be detrimental to optimal osseointegration. Recommendations for physiotherapeutic exercises have now been established based on these findings, which consider exercises to be more or less strenuous, although these assumptions have not yet been confirmed scientifically. Our approach to addressing this gap in knowledge is to use instrumented implants, where we are able to determine the actual joint loading throughout postoperative physiotherapy.
Intra-articular loading during physiotherapeutic exercises
Our primary goal is to determine the joint loading during common physiotherapeutic exercises, but we also aim to investigate the influence of different movement patterns, including faster movement velocity or greater range of motion. Furthermore, the influence of several gait modifications is being investigated, such as the often observed limping of patients with osteoarthritis.
Understanding the loading conditions in the hip, knee, shoulder and spine will provide comprehensive knowledge of the acting loads. These findings will provide a basis for revising recent recommendations for implant requirements, as well as support patients, clinicians and therapists in order to improve individual strategies for rehabilitation. [Schwachmeyer et al., 2013]
Heat application on the skin and its influence on the intra-articular temperature
Many patients with rheumatoid or orthopaedic symptoms report joint pain. Rheumatoid joints, especially with acute inflammatory arthritis, often exhibit an increased intra-articular temperature. This raise in temperature may increase the activity of cartilage-destroying enzymes and accelerate degeneration of joint cartilage. Pain is often treated using thermal applications in the form of heat or cold packs applied to the skin. Hence, an increase of intra-articular temperature caused by superficial heat application could also have a similar detrimental effect on rheumatoid joints. Through using instrumented implants with the ability to measure the intra-articular temperature, it is now possible to investigate the influence of thermal applications on joint temperature.