Surgical navigation robot improves hip surgery training
20 February 2008
A pilot study at Imperial College, London has shown that a surgical
navigation robot could improve hip surgery and help end painful repeat hip
operations. The new robot, called the Navigation Wayfinder, was developed by
Imperial College spin-out Acrobot and UK medical device company Corin Group.
It made medical undergraduates three times more accurate during practice hip
Professor Justin Cobb, Head of the Biosurgery and Surgical Technology
Group at Imperial College London, and co-founder of Acrobot, conducted the
trial using 32 undergraduate medical students practising hip resurfacing
arthroplasty procedures — a method for correcting painful hip bone
deformities by coating the femoral head with a cast of chrome alloy.
The pilot study tested whether planning before an operation, combined
with the new robot could increase the success rates of students.
The operation is technically demanding and requires precision and
accuracy. Surgeons rely on years of experience and on different cameras,
lasers and hand-held tools to help them navigate during an operation.
Inexperienced surgeons often face a steep learning curve to gain the
experience necessary to carry out hip resurfacing operations. Until now,
this has only been gained through repeatedly performing the operations. This
can cause problems because if hip bones are repaired incorrectly wear and
tear occurs, requiring patients to undergo further painful and expensive
Wayfinder (see image on right) navigation system is similar to a GPS
tracking system. It helps the user to navigate during surgery by plotting
correct surgical incisions. It also calculates the correct angles for
inserting chrome alloy parts needed to repair hip bones.
It has twin digital arms protruding from a console. One senses the
movement of surgical tools as they slice through a patient’s hip area. The
other takes detailed images of the bones. This information is fed into
software which generates a virtual model of a patient’s hip as it is being
operated on. Similar to a 3D roadmap, it allows the user to plot the
progress of an operation as they are performing it — a vital technique for
ensuring that it is being carried out correctly.
Professor Cobb saw the benefits of incorporating the Wayfinder into
undergraduate training and developed a three-step training programme.
Students used model replicas of deformed hip bones for the trial, scanned
by the Wayfinder’s digital arm. This information was used to create a 3D
virtual model of the bone area.
The Wayfinder’s computer programme developed an operation plan setting
out the actions required for undergraduates to correct the hip deformity.
Students were asked to carry out a virtual operation on the 3D model of
the hip. Using the tool tracking arm, they practised techniques for
fastening chrome alloy on virtual deformed hip bones. This built up their
confidence, technique and skill.
They were asked to perform surgery on model casts of real hip bones. By
using the Wayfinder to help them navigate, undergraduates were able to
attach a post to the centre of the femoral head and thread it, via a guide
wire, to the femur.
A resurfaced hip bone with a
cast of chrome alloy
Professor Cobb then asked students to perform the same operation using
conventional navigation tools. One method involved the use of jigs and
alignments. Similar to geometry sets, they are metal surgical guides which
helped undergraduates to manually align the femoral head as they attached it
to the femur.
The second method required students to operate using an optical
navigation device. A camera and pinpoint lights were used to create an image
of the hip on a computer screen. This was used by undergraduates for visual
navigation during the procedure.
Professor Cobb compared how undergraduates performed with each different
method. He found that they were three times more accurate and precise using
the Wayfinder than if they used the two other conventional methods.
Clinical trials using the Wayfinder are currently being carried out at
Warwick Hospital, Bath Hospital, Truro Hospital and the London Clinic.
Professor Cobb believes his training method could be applied throughout the
UK to improve outcomes for patients. He said:
“Our research proves that we can take untrained surgeons and make them an
expert in a new technique rapidly. More importantly, we’ve also demonstrated
that no patient has to be on an inexperienced surgeon’s learning curve. This
could significantly improve a patient’s health and wellbeing and ensure they
do not have to undergo repeat operations.”