Measuring functional outcome after total hip replacement with subject-specific hip joint loading

Abstract

Total hip replacement is an often-performed orthopedic surgical procedure; the amount of procedures undertaken will increase since our life expectancy is growing. In order to optimize function, hip biomechanics should be restored to as near normal as possible. The goal of this pilot study was to determine whether or not it is feasible to compute the vectorial hip reaction force pathways on the head of the prosthesis and the force angles relative to the cup of the prosthesis that occur during gait in total hip replacement patients, serving as an objective measurement of the functional outcome following hip replacement.A three-dimensional gait analysis, measuring ground reaction forces and kinematics, was performed. The data retrieved from the gait analysis was used as the input for the musculoskeletal model to compute vectorial joint reaction forces for data processing. To evaluate the position and orientation of the joint reaction forces, the force path, as well as the force angles for the operated and non-operated joint, has been calculated during the stance phase of the specific leg.The force path for subject 2 on the non-operated side is only located in the posterior-lateral quarter, as is the force path for subject 1. In contrast to this subject, the force path for subject 2 at the operated hip joint can be found only within the anterior quarter of the head of the implant, where it is nearly equally distributed in the medio-lateral half of the prosthesis head. The force-inclination angles on the cup of subject 1, with respect to the plane of the socket face, indicates that the force vector is mainly positioned in the same quadrant when compared with subject 2 (in a cup-fixed coordinate system). The force-anteversion angle behaves similarly to the force-inclination angle, even when the effects are not as pronounced.The proposed methods in this article are aiming to define two functional outcomes of total hip replacement that are related to wear and rim loading. It is accepted that wear is not only a function of time, but a function of use. Owing to the methods listed in this article, we are able to determine a) the applied force and b) the sliding distance (force pathway) in a subject-specific manner. The computed hip-reaction force angles and the distance to the rim cup are a measurement for cup or rim loading, and occurs in the so-called safe-zones. This method may well give us insight into the biomechanical situation during gait, after receiving total hip replacement, that we need to fully understand the mechanisms acting on a hip joint and to prove a possible increase of functional outcome after receiving total hip replacement.

Identifying clinically meaningful benchmarks for gait improvement after total hip arthroplasty

“…9,11,17,21 Normal walking mechanics may also not necessarily be desirable, because high values of certain gait parameters may increase potentially damaging joint forces. [22][23][24] Finally, although we know from our recent work that there is an association between gait improvement and clinical improvement, 20 we do not yet know how much improvement, or what final postoperative outcome may be meaningful to a given patient. There is a need for clinically relevant benchmarks for gait improvement after THA.…”

“…A tacit assumption is that normal walking mechanics is the goal, but this goal may be unattainable for many patients because of the significant impairment present before surgery . Normal walking mechanics may also not necessarily be desirable, because high values of certain gait parameters may increase potentially damaging joint forces . Finally, although we know from our recent work that there is an association between gait improvement and clinical improvement, we do not yet know how much improvement, or what final postoperative outcome may be meaningful to a given patient.…”

Optimization-based dynamic prediction of kinematic and kinetic patterns for a human vertical jump from a squatting position

“…Virtual human modeling software systems, such as musculoskeletal modeling tools and digital manikins, are commercially available and used in many fields like industrial design [1], sport equipment design and performance optimization [2], orthopedics [3][4][5], ergonomics [6,7], occupational biomechanics [8], rehabilitation [9], and clinical biomechanics [10]. In B S. Davoudabadi Farahani sdf@m-tech.aau.dk 1 these applications, the human models must usually be driven by motion capture data.…”

Musculoskeletal Modeling for Hip Replacement Outcome Analyses and Other Applications

“…Then detailed biomechanical analyses of the postoperative loading conditions can be performedfor example, the differences between operated and nonoperated joints can be quantified. 2 Furthermore, this approach can then be combined with simulation at the tissue level through, for example, finite element analysis, to tease out the mechanobiologic effects of surgical intervention. 3 In addition to becoming a standard analysis tool for surgery and postoperative analyses, MM is also set to have an impact on longer-term follow-up issues such as rehabilitation programs, further improving patient care.…”