Patient-Specific 3D Guided Correction in High Tibial Osteotomy

The use of patient specific cutting guides with high tibial osteotomy is
thought to achieve a higher accuracy of the planned correction compared to the
conventional osteotomy planning and surgical technique. The achieved accuracy
of the conventional osteotomy depends greatly on the experience of the surgeon
to plan the correction pre-operatively and carry out this correction during the
operation. Using a CT-scan to plan the tibial correction automatically and
subsequently using 3D-printed cutting guides during the operation removes this
dependence on the skill-level of the surgeon. This study aims to investigate
the effect of this new technique on the accuracy of correction during a high
tibial osteotomy.

The primary objective is to investigate whether the use of patient-specific
cutting guides for an open wedge high tibial osteotomy (HTO) provide a more
accurate correction relative to the preoperative planning compared to the
conventional osteotomy method.

The secondary objective evaluates the difference between the CT-based model
planning compared to the conventional planning method performed by surgeons on
full-leg X-rays. Furthermore, the costs of the radiology department (CT-scan),
3D planning and printing, surgical costs (sterilization unit) and operative
time in using patient-specific cutting guides versus conventional osteotomy
surgery will be compared between the two methods.

This is a prospective single-blinded randomized controlled study, where the
patients will be blinded for the use of the 3D planned and printed saw guide.

In the intervention group a patient-specific cutting guide will be used to
assist positioning and angle of the saw cut, and provide guidance on the degree
of angular correction from the pre-operative plan. In the control group the
conventional surgical osteotomy technique, without a patient-specific cutting
guide will be used.

For all study patients both a full-leg radiograph as well as a CT-scan will be
made. The former will be used to perform the standard practice osteotomy
planning, while the latter will be used to automatically calculate the planned
correction angle. Post-operatively, all patients will receive another CT-scan
to determine the achieved correction.

Patients will undergo a pre- and postoperative CT-scan (integrated in regular
care, which means combined with a regular visit to clinic) of the affected leg
additionally to standard care. Other pre-, per- and postoperative care are
identical between the two groups and identical to regular care.

The radiation load from the CT is calculated by our radiology expert and
estimated at 0.82 mSv per scan (1,64 mSv total). This extra radiation load
leads therefore to a slight increased risk. According to the publication ICRP
62 *Radiological Protection in Biomedical Research*, this is justified because
this study will lead to acquisition of knowledge, directly aimed at cure of
disease.