TLEMsafe: Improving safety and predictability of complex musculo-skeletal
surgery using a patient-specific navigation system. Part IIa: validation with sarcoma patients pre and post OR.

In the treatment of sarcoma of the lower limb, whether it be osteosarcoma,
Ewing sarcoma or soft tissue sarcoma, the surgeon has to make many important
decisions. The first is whether to amputate or to attempt to preserve the limb.
With increased surgical expertise and improved diagnostic imaging techniques,
amputation can nowadays be avoided for the vast majority of patients. These
patients undergo limb-saving surgery. In this procedure, the surgeon always
excises the tumor with a margin around it to prevent local recurrences. In
spite of all the advancements made in the surgical treatment of sarcoma, the
consequences of a specific excision margin on post-OR functionality for a
specific patient is sometimes unknown to the surgeon. In the case of an
osteosarcoma, the surgeon removes the affected part of the bone including a
margin of surrounding soft tissue after which a bone-replacing prosthesis has
to be placed. The consequences of this extensive surgery on post-OR
functionality are hard to predict. To improve the predictability of limb-saving
surgery, the surgeon would benefit greatly from a pre-planning system that
could show him the effects of several surgical scenarios on post-OR
functionality. The TLEMsafe project will create such a system. To this end, we
will use a state-of-the-art musculo-skeletal (M-S) model of the lower limb
which has recently been developed. In this model, the performance of basic
activities of daily living after surgery can be simulated. In order to simulate
activities of daily living after surgery in an accurate manner, the model first
has to be made patient-specific and undergo rigorous validation. In the first
part of the project (CMO 2011/011), healthy-subject-specific M-S models have
been created, which are currently being validated. In the present phase of the
project, we will create and validate patient-specific post-OR M-S models of
sarcoma patients. This is a crucial step towards the construction of a reliable
surgical pre-planning system.

To create and validate patient-specific post-OR M-S models of the lower limb of
sarcoma patients. The primary goal is to see if the model can accurately
predict whether a patient can or cannot walk after surgery.

Observational prospective cohort study.

Participation entails an MRI scan pre-OR and 6-9 months post-OR, and a session
6-9 months post-OR during which the patient performs basic activities of daily
living. Each MRI scan takes about 45 minutes. The scans are made exclusively of
the lower limb. The activities of daily living that patients have to perform
6-9 months post-OR take place in the motion laboratory of the department of
Rehabilitation. This session takes three to four hours to complete. In this
session, 3-D kinematics, ground reaction forces measurements and
electromyography will be employed to measure the patient*s post-OR
functionality during activities of daily living such as walking, getting up
from a chair, stepping over an obstacle, and maintaining balance while standing
on a moveable platform.

The MRI scans are painless and not dangerous. The largest burden of
participation lies in the fact that patients have to be informed about the
study, asked for participation, and undergo an extra pre-OR MRI scan in the
month between the first outpatient visit to the surgeon and the surgery itself.
To lower this burden, the scan will be scheduled as much as possible on a day
that the patient is already at the RUMC for other treatment-related visits. The
post-OR MRI scan and the motion laboratory session will also be planned on the
same day as treatment-related visit days as much as possible. All of the
measurements in the motion laboratory are regularly performed in this
laboratory and are non-invasive and painless. If a patient anticipates or
experiences pain during any of the exercises, that exercise will be skipped.