PRAXIM SELECT PEER-REVIEWED PUBLICATIONS
TOTAL KNEE RECONSTRUCTION
Navigated revision knee arthroplasty using a system designed for
primary surgery.
Massin P, Boyer P, Pernin J, Jeanrot C.,
Comput Aided Surg. 2008 Jul;13(4):179-87.
Abstract
While
navigation is now recognized as an efficient tool for improving
femoro-tibial alignment of primary knee prostheses, its use in
revision surgery has not yet been fully evaluated. We describe a
procedure based on a bone morphing acquisition performed on the
surface of the original implants, followed by a dependant bone cut
sequence (tibia first). Using the current system, a preoperative
CT-scan measurement of the original femoral component was required.
Knee balancing was achieved using spacer blocks, with the trial tibial
component and the original femoral component still in place.
Preliminary experience from 19 cases, some with severe bone loss
requiring reconstruction, is reported. A retrospective comparison to
10 non-navigated revision cases performed concomitantly by the same
operating surgeon was carried out. Although there was no significant
difference in the number of outliers for the two series, navigation
appeared to be a valuable aid in reconstructing both bone extremities,
while controlling the level of the joint line. However, definitive
validation requires further prospective and comparative investigations
in larger series.
Clinical
Results of Navigated Total Knee Arthroplasty in Patients with
Posttraumatic Deformity and Arthrosis
A.P. Schulz, S. Magerlein, S Fuchs, A. Unger, L. Simon, B. Kienast, M. Faschingbauer and A. Paech,
Research Journal of Medical Sciences 1 (3):
178-182, 2007
Abstract
Trauma surgeons are often less exposed to large caseloads of
primary osteoarthritis, compared to purely `elective`orthopaedic
surgeons. The experience in total knee arthroplasty is thereby
markedly On the other hand, posttraumatic knee arthrosis is often
accompanied by severe deformity and axis deviation. In theory,
navigated arthroplasty can overcome some of the problems in this
setting. Aim was the evaluation of the navigated technique of
Total Knee Arthroplasty (TKA), including the technical
difficulties, the learning curve and the feasibility in severe
bony deformity. Setting is a level I trauma center. Patients and
Methods: Between July 2004 and December 2005 we treated 49
Patients with a mean age 62 yrs. (32-82). All had a severe
Arthritis of the knee joint due to trauma (diagram 1), 58% were
male, in 51% the treatment was under the Workers injury
compensation scheme. On average patients had 3.02 previous
operations (1-9, including arthroscopies). In all cases a
navigational system (PRAXIM, Tronche/France) was used with
infrared-tracking and bone-morphing software. The implant was a
mobile bearing LCS knee (DePuy/USA). Study setup was prospective,
follow up on average 14.5 months (11-25) including the Knee
Society Score results, In 4 cases the procedure was finished in a
conventional technique, reasons were decision of the surgeon, a
missing femoral cut block and a broken screw of the
tracker-fixation. In one case a hinged prosthesis was implanted
due to instability. There was no failure of the navigational
system. There was a clear learning curve. Preoperative extension
deficit was improved from average 7.1° (0-30°)-1.67° (0°-10°)
postop., flexion contracture improved from av. 95°-103°. The
combined knee society score improved from 83 points preoperatively
to 157 points at F/U. Navigated knee endoprosthesis is reliable
tool for the trauma surgeon with few technical problems.
Especially for surgeons with less experience in TKA, planning of
implant size and position is very helpful. With posttraumatic
deformity the surgeon can gain valuable information and assistance
to improve alignment and ligamentous balancing.
Bone
Morphing: 3D reconstruction without pre- or intra-operative imaging
E.Stindel, N.Perrin, JL.Briard, S.Lavallée, C.Lefevre, J.Troccaz,
Stiehl James B., Navigation and MIS in Orthopedic
Surgery (Hardcover), Chapter 5, Springer, 2006
Navigated Total Knee Arthroplasty and the Surgetics Bone Morphing
System
E.Stindel, JL.Briard, C.Plaskos, J.Troccaz,
Stiehl James B., Navigation and MIS in Orthopedic
Surgery (Hardcover), Chapter 16, Springer, 2006
Detection of the center of the hip joint in computer-assisted surgery:
an evaluation study of the Surgetics algorithm.
Stindel E, Gil D, Briard JL, Merloz P, Dubrana F, Lefevre C.
Comput Aided Surg. 2005 May;10(3):133-9.
Abstract
OBJECTIVE: The aim of this paper is to assess the accuracy of an
algorithm implemented by PRAXIM in the SURGETICS navigation station
for detection of the hip center. This study will assess the robustness
and accuracy of the algorithm in various clinical situations such as
those involving non-sphericity of the femoral head, motion of the
pelvis during hip center detection, and restricted range of motion.
MATERIALS AND METHODS: The localization of the hip center, based on
kinematics, relies on the recording of n successive positions of the
femoral rigid body in the localizer reference system during a passive
circumduction motion of the hip joint. Therefore, the shape of the
clouds of points acquired may vary from one acquisition to the next.
To allow a comprehensive study of the consequences of these variations
for hip center detection, we developed a simulator to generate
numerous clouds of points. Results given subsequently for each test
are the values of the difference between the femoral mechanical axis
computed with C(c), the computed hip center, and the same axis
computed with C(o), the reference hip center. RESULTS: Test 1:
Sensitivity to noise. The errors ranged from 3.33 E - 12 (SD 3.29E -
12) for a noise of 0 mm to 8.18E - 1 (SD - 7.05E - 1) for a noise of
15 mm. Test 2: Sensitivity to the shape of the acquisition motion. All
trajectories gave an error < 1 degrees . Test 3: Sensitivity to
restricted range of motion. No value > 1 degrees was found during this
test. Test 4: Sensitivity to the distance between two points of the
cloud. No value > 0.5 degrees was found during this test. Test 5:
Sensitivity to the number of points included in the cloud. No value >
1 degrees was found during this test. CONCLUSIONS: The Surgetics
algorithm is robust to noise, can compensate for pelvic motion, and
can be used even in the case of restricted range of motion.
Bone Morphing versus
freehand localization of anatomical landmarks: consequences for the
reproducibility of implant positioning in total knee arthroplasty
Perrin N, Stindel E, Roux C.
Comput Aided Surg. 2005 Sep-Nov;10(5-6):301-9
Abstract
OBJECTIVE: This
study analyzed the influence of the acquisition method in image-free
computer-assisted total knee arthroplasty (CAS-TKA), and the
reproducibility of implant planning using BoneMorphing, a 3D
morphometric model obtained by a 3D-to-3D elastic registration of
statistical models to sparse point clouds acquired directly on the
bone surface with a pointer. MATERIALS AND METHODS: Five surgeons (one
expert, four trainees) each performed a CAS-TKA hybrid protocol based
on morphometric models and landmarks on a cadaveric knee 10 times. In
addition, several additional landmarks were digitized during each
acquisition. The reproducibility of the implant positioning and
sizing, as determined by an implant planning algorithm with
morphometric models, was compared to direct digitization accuracy.
RESULTS: Femoral and tibial implant positioning parameters with the
hybrid protocol resulted in intra-surgeon standard deviations (SDs) of
less than+/-1.4 degrees for rotation and 1.9 mm for translation for
all surgeons in all directions except for tibial axial rotation (the
only parameter determined by a digitized landmark and not recomputed
in the 3D model). The variability in individual landmark digitization
varied from 2 to 5 mm SD for certain landmarks, with ranges of 15-25
mm across all surgeons. The comparison study showed an improvement in
femoral rotation reproducibility with the morphometric model when
using the posterior condylar axis. Tibial implant reproducibility for
each method was comparable, with the morphometric model giving better
results in well-digitized areas such as the tibial plateau.
CONCLUSION: A CAS-TKA protocol based on a deformed statistical model
offers reproducible implant positioning. Some landmarks, such as
distal condyles, show sufficient reproducibility in the direction of
interest, while others, such as the anterior tibial tubercle, can lead
to hazardous implant positioning. This should be taken into
consideration when designing a CAS-TKA system with bony landmarks. In
areas where a sufficient number of points have been digitized with
good coverage, such as on the distal and posterior femoral condyles or
the tibial plateau areas, the information derived from the 3D model is
more accurate and reproducible than that derived from digitization.
Good training and a guiding user interface are essential to guarantee
coverage quality.
Computerised and
technical navigation in total
knee-arthroplasty
U.
Böhling, H. Schamberger, U. Grittner, J. Scholz,
J Orthopaed Traumatol (2005) 6:69–75
Abstract
The
objective of the study was to evaluate the precision, concordance,
practicability and the early clinical outcome of the use of a
computerised navigation system in a comparative study with a group of
100 patients. Two groups of 50 patients each underwent implantation of
a bicondylar knee prosthesis either by means of the freehand
navigation system or by means of technical instrumentation. We found
that the computerised navigation system provided a higher precision
than the technically instrumented implantation: 94% of the prostheses
implanted with the navigation system have an alignment within a range
of -3° to 3° on of the Mikulicz line. Only 46% of the patients
operated by means of the technical instrumentation reached this
aspired result. Furthermore, the navigation system showed smaller
ranges in the deviation of the aspired alignment. The radiological and
computer-modeled alignment values differed both pre- and
postoperatively, but to a larger extent before surgery. The varus or
valgus deviations of the axis were more distinct radiologically under
the weight of the patient’s body than in the computer model. The
clinical outcome examined by the use of the HSS score after a mean
followup of 7 months is good in both groups, and without significant
differences. On average, the duration of surgery was 13 minutes longer
in the computerised navigation group. We conclude that the benefit of
the computerised navigation system is represented by the high
improvement of precision. Achieving early clinical results identical
to those in the technical instrumentation group, we expect a reduction
of aseptic loosening in the computerised navigation group.
Knee
Prosthesis navigation System
J.Sholtz, V.Makris, H.Schamberger, G.Panides,
Journal of Bone & Joint Surgery Br. 2004, 86-B:SUPP
II; 181
Surgetics Total Knee Arthroplasty using Bone-Morphing-preliminary
results based on 60 clinical cases
E.Stindel, JL.Briard, P.Merloz, F.Dubrana, S.Plaweski, C.Lefevre,
Proceedings of CAOS 2003, Marbella – Spain.
The bone
morphing : 3D morphological data for Total Knee Arthroplasty
Stindel E., Briard J., Merloz P., Plaweski S., Dubrana F., Lefevre C., Troccaz J.
Computer-Aided Surgery 7(3) , (2002) 156-168
Abstract
OBJECTIVE: The clinical outcome of a total knee arthroplasty (TKA) is
mainly determined by the accuracy of the surgical procedure itself. To
improve the final result, one must take into account (a) the alignment
of the prosthesis with respect to the mechanical axis, and (b) the
balance of the soft tissues. Therefore, morphologic data (such as the
shape of the epiphysis) and geometric data are essential. We present a
new method for performing TKA based on morphologic and geometric data
without preoperative images. MATERIALS AND METHODS: The global method
is based on the digitization of points with an optical 3D localizer.
For the morphologic acquisitions, we use a method based on the
registration of sparse point data with a 3D statistical deformable
model. To build the mechanical axis, we use a kinematics method for
the hip center and digitization of anatomical landmarks for the ankle
centers. The knee center is not determined by digitization or
kinematics of the knee, as this would not be accurate. The surgical
planning relies totally on the soft-tissue balance, which is the key
issue for a good kinematics result. RESULTS: We have used this system
for 6 months in a randomized clinical trial involving 35 patients to
date. For the first 11 patients that could be measured in the
navigation group, the postoperative frontal alignment was within the
range of 180 +/- 3 degrees. Fluoroscopic assessment of the soft-tissue
balancing will be performed at the conclusion of an extended 2-year
study to evaluate the results from a functional point of view.
CONCLUSION: Bone Morphing is an accurate, fast, and user-friendly
method that can provide morphologic as well as geometric data. We have
introduced the important notion of soft-tissue balancing into the
intraoperative planning step to optimize the kinematics as well as the
anatomy. Therefore, this method should be considered as an alternative
to the CT-based method.