QUANTIFYING PROSTHESIS ALIGNMENT IN TRANSTIBIAL BONE-ANCHORED PROSTHESIS USERS

We aim to investigate whether a standing x-ray has the potential to being used
for optimizing prosthetic alignment. In clinical practice, frontal prosthetic
alignment adjustments are often made to help solve the frequently present knee
pain in transtibial bone-anchored prosthetic (BAP) users. Knee pain limits
activity and participation level in the short term, and in the long term may
ultimately lead to permanent damage in the knee, such as knee osteoarthritis.
Currently, optimizing prosthetic alignment is an iterative process and although
it often results in fewer complaints, it is still unclear which alignment is
most optimal for BAP users. Additionally, we lack insight into the impact of
prosthetic alignment on the implant and on other joints.
We hypothesize that a symmetric weight-bearing line alignment results in more
symmetrical frontal plane hip- and knee moments during gait. A standing x-ray
is a tool for obtaining this weight-bearing line and may therefore be a useful
tool to optimize prosthetic alignment in BAP users. By respecting the
individual anatomy, we expect that this alignment strategy has a preventive
effect on the development of knee pain. Secondly, we hypothesize that imposed
systematic alignment adjustments result in a structural change on knee and hip
and implant moments. This relation is of clinical importance, since it could be
used to determine the necessary prosthetic alignment adjustments for BAP users
who present themselves with pain or discomfort within clinical practice.
Since it is important to translate the knowledge of the weight bearing line in
a x-ray, towards widely accessible resources, we introduce a tertiary purpose.
We will investigate if the accessible tools for the Prosthetic and Orthotic
Industry, such as the LASAR 3D and 3D motion capture, will be of use to
implement findings of this study. While these systems are widely accepted, the
use of the LASAR3D has not been validated. It is therefore necessary to
investigate the clinimetric properties of the LASAR3D and its potential role in
optimizing and monitoring the prosthetic alignment in transtibial BAP users.
A better understanding of alignment and developing a more objective alignment
approach will result in shift from a reactive treatment towards a proactive
treatment strategy within prosthetic facilities. It has the potential to
prevent or reduce prosthetic related problems limiting health-related quality
of life.

The primary aim is to investigate if the weightbearing line alignment using a
full-leg radiographic image results in more symmetrical frontal plane hip- and
knee moments during gait. As a secondary aim, we will evaluate a) the
relationship between imposed systematic changes in alignment and knee, hip, and
implant moments and b) the effects of weight-bearing line alignment method on
short term (within 2 weeks) physical complaints. The tertiary aim is to
investigate the correlation between the weight-bearing line in a radiographic
image and a weight-bearing line that can be obtained using 3D motion capture.
Additionally, we will investigate the clinimetric properties of the LASAR3D.

A mono-center cross-sectional study.

The burden or risks associated with this research are limited and are not
basically different from the risks and burden of patients visiting a
rehabilitation facility for regular bone anchored prosthetic adjustments.
Standing x-rays and alignment changes are routinely conducted during
rehabilitation and follow-ups for bone-anchored prosthetic users at the
Radboudumc. The participants of this study may benefit from an optimized
alignment. In general, a better understanding of prosthetic alignment
potentially prevents BAP users from experiencing pain and discomfort during
prosthetic use and may lead to preventing permanent damage of the knee.