[Early assessment of the risk of later implantloosening using Roentgen Sterophotogrammetric Analysis (RSA)]. / Früherkennung des Risikos der späteren Implantatlockerung mittels der Röntgen Stereophotogrammetrischen Analyse (RSA).

BACKGROUND: Aseptic implant loosening is the most common cause of implant revisions in total hip and total knee arthroplasty. Roentgen Stereophotogrammetric Analysis (RSA) represents the current gold standard for the in-vivo assessment of implant fixation. PRESENT SITUATION: Long-term clinical trials have shown that continuous implant migration within the first two postoperative years correlates strongly with a later aseptic loosening. Thus, the implant migration measured with RSA can be regarded as a reliable surrogate marker for later implant loosening. Over the past 40 years, RSA has been continuously further developed, and the model-based RSA approach has reduced the effort involved since markers attached to implant are no longer needed. PERSPECTIVES: The RSA method is gaining importance in the certification process of new orthopaedic implants-for example, the Dutch Orthopedic Society has recommended phased-introduction and RSA studies for new hip implants. Furthermore, in the context of the new EU Medical Device Regulation (MDR), which took effect in May 2017, RSA gained relevance for investigating clinically unproven implants. Critics who associate MDR with hindering innovation can be countered in that the RSA method provides a predictive assessment of implant fixation after only two years of follow-up, which is significantly shorter than standard long-term clinical trials.

[Instrumented gait and movement analysis of musculoskeletal diseases]. / Instrumentelle Gang- und Bewegungsanalyse bei muskuloskelettalen Erkrankungen.

Instrumented 3-dimensional gait analysis is increasingly being used for the evaluation of movement disorders in orthopedic and neurological musculoskeletal diseases. Due to the high reliability of the measurements the procedures are appropriate for diagnostic purposes as well as for outcome assessment after conservative or surgical interventions. Contrary to conventional clinical assessments gait analysis parameters are able to demonstrate a normal physiological gait pattern that can be achieved with improved kinematic and kinetic parameters. For a suitable application in clinically relevant problems the limitations of the procedures should be taken into account. Due to the high instrumental involvement combined with time and cost expenditure instrumented gait analysis will probably not develop to a clinical routine procedure. Nevertheless, an excellent set of information for answering clinical questions is provided. The present contribution presents selected measurement procedures and technologies and illustrates the wide variety of possibilities with the use of selected clinical examples.

Development and clinical validation of an unobtrusive ambulatory knee function monitoring system with inertial 9DoF sensors.

Patients suffering from end-stage knee osteoarthritis are often treated with total knee arthroplasty, improving their functional mobility. A number of patients, however, report continued difficulty with stair ascent and descent or sportive activity after surgery and are not completely satisfied with the outcome. State-of-the-art analyses to evaluate the outcome and mobility after knee replacement are conducted under supervised settings in specialized gait labs and thus can only reflect a short period of time. A number of external factors may lead to artificial gait patterns in patients. Moreover, clinically relevant situations are difficult to simulate in a stationary gait lab. In contrast to this, inertial sensors may be used additionally for unobtrusive gait monitoring. However, recent notable approaches found in literature concerning knee function analysis have so far not been applied in a clinical context and have therefore not yet been validated in a clinical setting. The aim of this paper is to present a system for unsupervised long-term monitoring of human gait with a focus on knee joint function, which is applicable in patients' everyday lives and to report on the validation of this system gathered during walking with reference to state-of-the-art gait lab data using a vision system (VICON Motion System). The system KINEMATICWEAR - developed in close collaboration of computer scientists and physicians performing knee arthroplasty - consists of two sensor nodes with combined tri-axial accelerometer, gyroscope and magnetometer to be worn under normal trousers. Reliability of the system is shown in the results. An overall correlation of 0.99 (with an overall RMSE of 2.72) compared to the state-of-the-art reference system indicates a sound quality and a high degree of correspondence. KINEMATICWEAR enables ambulatory, unconstrained measurements of knee function outside a supervised lab inspection.