ORIGINAL ARTICLE
Robotic technique improves entry point alignment
for intramedullary nailing of femur fractures compared
to the conventional technique: a cadaveric study
Eduardo M. Suero
1
•
Ralf Westphal
2
•
Musa Citak
1
•
Nael Hawi
1
•
Emmanouil Liodakis
1
•
Christian Krettek
1
•
Timo Stuebig
1
Received: 31 May 2017 / Accepted: 1 August 2017 / Published online: 11 August 2017
Ó Springer-Verlag London Ltd. 2017
Abstract We aimed to test whether a robotic technique
would offer more accurate access to the proximal femoral
medullary cavity for insertion of an intramedullary nail
compared to the conventional manual technique. The
medullary cavity of ten femur specimens was accessed in a
conventional fashion using fluoroscopic control. In ten
additional femur specimens, ISO-C 3D scans were
obtained and a computer program calculated the ideal
location of the cavity opening based on the trajectory of the
medullary canal. In both techniques, the surgeon opened
the cavity using a drill and inserted a radiopaque tube that
matched the diameter of the cavity. The mean difference in
angle between the proximal opening and the medullary
canal in the shaft of the femur was calculated for both
groups. Robotic cavity opening was more accurate than the
manual technique, with a mean difference in trajectory
between the proximal opening and the shaft canal of 2.0°
(95% CI 0.6°–3.5°) compared to a mean difference of 4.3°
(95% CI 2.11°–6.48°) using the manual technique
(P = 0.0218). The robotic technique was more accurate
than the manual procedure for identifying the optimal
location for opening the medullary canal for insertion of an
intramedullary nail. Additional advantages may include a
reduction in total radiation exposure, as only one ISO-C 3D
scan is needed, as opposed to multiple radiographs when
using the manual technique.
Keywords Entry point Á Intramedullary nailing Á Robotic
fracture reduction Á Telemanipulated fracture reduction
Introduction
Intramedullary (IM) nailing is a common surgical approach
for the treatment of femoral shaft fractures. This is a
minimally invasive technique by which a nail is inserted
longitudinally along the medullary canal of the femur
through an opening at the proximal end of the bone. This is
a highly successful procedure with union rates above 90%
[1, 2].
However, the initial access to the medullary cavity at the
proximal end of the femur can be challenging due varying
anatomic features, and experts differ as to where the
location of the optimal entry point lies [3]. When the entry
point is not well aligned with the proximal portion of the
medullary cavity, the additional force required to insert the
nail can cause it to deform. In addition, malalignment and
repeated reaming may lead to iatrogenic fractures [4–6].
Moreover, the conventional manual technique requires the
use of radiographic imaging for guidance in two planes and
radiation exposure is a concern.
Computer navigation has been implemented to improve
accuracy and precision in orthopedic procedures. Wilharm
et al. demonstrated the feasibility of fluoroscopy-based
navigation for intramedullary nail insertion [7]. Crook-
shank et al. showed that fluoroscopy-based computer nav-
igation has similar accuracy and improved precision
compared to the conventional technique [8].
In an effort towards achieving more accurate and precise
placement of intramedullary nails for femoral shaft frac-
tures [9–12], a robotic technique has been described that
may improve the accuracy and precision of the entry point
& Eduardo M. Suero
EduardoSueroMD@gmail.com
1
Trauma Department, Hannover Medical School,
Carl-Neuberg-Str. 1, 30625 Hannover, Germany
2
Institute for Robotics and Process Control, Braunschweig
University of Technology, Brunswick, Germany
123
J Robotic Surg (2018) 12:311–315
https://doi.org/10.1007/s11701-017-0735-8
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