DOS Afhandlingsdatabase

Titel på arbejdetKinematic investigation of knee osteoarthritis and arthroplasty designs - employing dynamic radiostereometry
NavnEmil Toft Petersen
Afdeling / StedUniversity Clinic for Hand, Hip, and Knee Surgery, Holstebro Regional Hospital and Department of Orthopaedics, Aarhus University Hospital
UniversitetAarhus University
  • Hip and knee surgery
Abstract / Summary

Osteoarthritis is a highly prevalent chronic disorder causing degenerative joint changes often associated with joint pain and disability limiting daily activities.1 The knee is the most commonly affected weightbearing joint in osteoarthritis. The prevalence of painful and disabling knee osteoarthritis (KOA) in adults over 55 years of age is 10%, and a quarter of those affected are severely disabled. Thus, KOA has a considerable impact on the patients’ physical and psychosocial health and well-being, but also generates a significant financial burden on the healthcare systems. In Denmark, with 60,000-65,000 patients consulting their general practitioner for KOA annually, and with half of these being allocated surgery, the present Danish arthritis- related expenses accrue to 11 billion DKK annually. In step with the increasing life expectancy and demographic changes, an increase is expected in the number of patients with disabling KOA and in the ensuing financial healthcare burden.

End-stage KOA can be treated surgically with total knee arthroplasty (TKA), which is a well-documented and successful treatment. However, up to 20% of patients are dissatisfied with the outcome. Considerable efforts have been devoted to reducing the number of dissatisfied patients; however, these efforts have not yet been successful. The search for ways to enhance patients’ health-related quality-of-life, performance and satisfaction have resulted in the widespread application of various TKA implant designs. However, for development of naturally functioning implants, it is fundamental to first understand the normal knee kinematics, the underlying pathomechanics of the osteoarthritis affected knees and the implant designs’ influence on knee mechanics.

The overall aim was two-fold: A methodological aim was to evaluate the accuracy of automated dynamic radiostereometric (dRSA) image registration methods; and a clinical aim was to investigate knee pathomechanics in osteoarthritic knees and the mechanical influence of knee arthroplasty designs during gait as a daily activity utilizing dRSA.
Study I presented an automated 2D/3D image registration for dRSA of the knee utilizing computed tomography (CT)-based volumetric bone models which was compared with model-configuration models as gold standard. Two different dRSA setups were evaluated. The image registration accurately measures the tibiofemoral joint kinematics and was not sensitive to the RSA setup. The automated method presented is clinically applicable for functional evaluation of native tibiofemoral joint kinematics and pathomechanics related to specific conditions such as ligament instability and bone dysplasia; and it is applicable for assessment of surgical results.
Study II presented an automated marker-free bone image registration method using radiostereometric analysis (RSA) for an arthroplasty knee joint in which the radiopaque implant components occluded or replaced a large part of the bone. The results revealed similar accuracy as the gold standard marker-based method. In addition, a synthetic volumetric implant model utilizing digitally reconstructed radiographs (DRR), which may provide more information to the automated registration, was designed and studied. However, in its present form, the volumetric implant model and DRR method did not markedly improve the traditional automated method.
Study III presented kinematic heterogeneity in patients with KOA during gait. The results revealed four subgroups, each displaying distinguished kinematic gait patterns that relate well to their clinical characteristics. In addition, these subgroups exhibited joint kinematics clearly different from those of healthy volunteers without KOA, including differences that were not present when comparing the entire KOA cohort with the healthy group.
Study IV demonstrated that the more anatomical Persona® Medical Congruent® (MC) bearing design changes tibiofemoral joint kinematics compared with the Persona® Cruciate Retaining (CR) bearing. The MC bearing provided an enhanced area of congruency while exhibiting more tibial anterior drawer throughout the gait cycle and greater external tibial rotation during the second half of the swing phase. Thus, the MC bearing design may help prevent so- called paradoxical motion, produce a more effective screw-home movement and contribute more stability during knee motion. This may improve the patient’s confidence in knee function during daily activities and thereby potentially lead to improved patient satisfaction.

The four studies together contribute to an enhanced understanding of the native and the artificial knee joint, which may inspire the development of improved and more patient-specific treatment strategies in the future. Furthermore, a method to aid clinicians to evaluate the implant fixation in any TKA patient was developed.

Andre oplysninger

Download afhandling