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Computer-Assisted Surgery (CAS) with
Minimally-Invasive Surgery (MIS)
Total Knee Replacement
A summary of some article on the
literature
Blood loss after total knee replacement:
effects of computer-assisted surgery.
J Bone Joint Surg Br. 2005
Nov;87(11):1480-2.
Kalairajah Y, Simpson D, Cossey
AJ, Verrall GM, Spriggins AJ.
Sportsmed SA, 32 Payneham Road, Stepney,
Adelaide 5069, South Australia. yega@orthospecialist.net
They evaluate the blood loss in 60 patients
having a total knee arthroplasty and divided randomly into two equal
groups, one having a computer-assisted procedure and the other a
standard operation.
The mean drainage of blood was 1351 in the
computer-aided group and 1747 in the conventional group.
There was a highly significant reduction in
blood drainage and the calculated Hb loss between the
computer-assisted and the conventional techniques.
This reduces risks at transfusion.
Computer-assisted surgery may also be useful for patients in whom
blood products are not acceptable.
Early assessment of the likely
cost-effectiveness of a new technology: A Markov model with
probabilistic sensitivity analysis of computer-assisted total knee
replacement.
Int J Technol Assess Health
Care. 2006 Spring;22(2):191-202.
Dong H, Buxton M. Brunel
University.
The objective of this study is to apply a
Markov model to compare cost-effectiveness of total knee replacement
(TKR) using computer-assisted surgery (CAS) with that of TKR using a
conventional manual method
Conclusions: Compared with conventional TKR,
computer-assisted TKR is a cost-saving technology in the long-term.
The "effect of CAS" is to reduce revision rates and complications
through more accurate and precise alignment,
Randomized control trial comparing
radiographic total knee arthroplasty implant placement using
computer navigation versus conventional technique.
J Arthroplasty. 2005
Aug;20(5):618-26.
Chin PL, Yang KY, Yeo SJ, Lo NN.
Department of Orthopaedic Surgery, Singapore
General Hospital, Singapore, Singapore.
The aim of this study is to assess the
radiological outcome of conventional techniques versus
computer-navigated surgery for total knee arthroplasty. Ninety
patients with knee arthritis were prospectively randomized into 3
groups: conventional technique: extramedullary (EM) and
intramedullary (IM) tibia guide versus computer navigation surgery
(CAS).
Our results showed that CAS had greater
consistency and accuracy in implant placement. In the coronal view,
93.3% in the CAS group had better outcomes compared with EM (73.4%)
and IM (60.0%). In the sagittal axis, 90.0% CAS also had better
outcomes compared with EM (63.3%) and IM (76.7%). Computer-navigated
total knee arthroplasty helps increase accuracy and reduce
"outliers" for implant placement.
J Bone Joint Surg [Br] 2004; 86-B; 372-7
CHAUHAN, S. K.; SCOTT, R. G.;
BREIDAHL, W.; BEAVER, R. J.
The Royal Perth Hospital,
Shenton Park Campus, Selby Street, Perth 6008, Western Australia.
It was decided to perform a blinded interim
analysis on the first 58 patients and a further 12 patients were
enrolled before the results of the interim analysis were available.
These showed a statistical significance in a number of radiographic
variables favouring computer navigation over the conventional
technique. The trial was therefore stopped on ethical grounds with
recruitment of 70 of the 75 patients.
One goal of computer-navigated surgery is to
implant components with greater accuracy, and reduce individual
defects and their cumulative effect. The statistically significant
improvement in seven of the eight radiological parameters for
alignment of the component using computer navigation over
conventional surgery is clear from the results. Furthermore, the
free-hand method avoids the need to penetrate the medullary canal
with its associated morbidity. In our matched study, 28% of the
conventional patients who had their femur instrumented, experienced
confusion, which was attributed to transient hypoxia. None of these
patients, nor the single patient in this group who experienced a
transient ischemic attack, suffered any long-term sequelae.
Almost as important as the improved accuracy is
the reduction in the number of outliers for the various radiographic
parameters. the reduction in outliers was greater in the navigation
group.
We observed more loss of blood in the
conventional group than in the computer-assisted group. We believe
this to be due partly to non-penetration of the femoral medullary
canal but also to care in soft-tissue management.
We believe that we have shown that
computer-assisted knee arthroplasty is more accurate than jig-based
knee arthroplasty and has a reduced morbidity in the short term.
J Bone Joint Surg [Br] 2004; 86-B; 682-7
BÄTHIS, H.; PERLICK, L.; TINGART,
M.; LÜRING, C.; ZURAKOWSKI, D.; GRIFKA, J.
In a prospective study two groups of 80
patients undergoing TKA had operations using either a
computer-assisted navigation system or a conventional technique.
Alignment of the leg and the orientation of components were
determined on post-operative long-leg coronal and lateral films.
Axial alignment of the limb with restoration
of the mechanical axis is a determinant of the outcome. A mechanical
axis within a range of ±3° varus/valgus is thought to be associated
with a better outcome. However, in previous studies post-operative
alignment of the limb exceeded a range of ±3° in up to 30% of cases.
The mechanical axis of the leg was
significantly better in the computer-assisted group (96%, within ±3°
varus/valgus) compared with the conventional group (78%, within ±3°
varus/valgus). The coronal alignment of the femoral component was
also more accurate in the computer-assisted group.
Computer-assisted TKA gives a better correction
of alignment of the leg and orientation of the components compared
with the conventional technique. Potential benefits in the long-term
outcome and functional improvement require further investigation.
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