Computer-assisted orthopaedic surgery (CAOS) leverages computer technology for enhanced accuracy in surgical procedures, including preoperative planning and intraoperative navigation. The document details various components and technologies involved in CAOS, such as tracking systems, smart tools, and robotic assistance, as well as their applications in hip and knee arthroplasties and spinal stabilization. Additionally, it addresses potential complications and challenges in navigation procedures and emphasizes the advantages of robotic surgery in terms of precision and minimal invasiveness.

1. COMPUTER ASSISTED
ORTHOPAEDICS SURGERY
MODERATOR: DR. SIVAPRASAD
PROFESSOR OF DEPARTMENT OF ORTHOPAEADICS
PRESENTOR:DR.SHEKHER MISRA

2. INTRODUCTION
• Computer assisted orthopaedic surgery(CAOS): It’s a
surgical technique that uses computer technology
preoperatively, intraoperatively and postoperatively to improve
the accuracy and outcome of orthopaedic surgical procedures.
• CAOS includes
• Pre operative planning
• Intraoperative navigation system
• Smart tools
• Remote surgery technologies

3. • Computers augment orthopaedic surgery by taking
advantage of these fundamental characteristics
Geometric precision
Reproducibility
Perfect memory
Lack of fatigue

4. HISTORY
• ROBOT is a term used for a machine that
automatically carries out various tasks, requires little or
no assistance from outside and can be programmable
• ROBODOC was first robot which was introduced in
1992 for planning and performance of total hip
replacement

5. What does the NAVIGATION in CAOS means?
Where is my (anatomical) target?
How do I reach my target safely ?
Where am I anatomically?
Where and how shall I position my implant?
So navigation is a successor or natural evolution of frame based stereotaxy.
• Guide the surgeon to find the specific anatomical target
• Avoid areas of risk
• Offer intraoperative orientation in the absence of anatomical landmarks
• Optimal alignment of implants
• 3D measurement system

6. COMPONENTS OF NAVIGATION SYSTEM
DATA ACQUISITION
TRACKING
REGISTRATION
VISUALISATION
VALIDATION

7. REGISTRATION
It matches the virtual word of images
to the real word of the patient and
operating room environment.
Registration refers to the correlation
between CT or fluoroscopic images and
a fixed points on the patient’s anatomy

8. CONNECTION
It is referred to as TRACKERS.
Connection is the actual or virtual link between the
patient and the CAOS system.
The most type of connection is via light emitting diode
arrays placed in the instruments used in surgery, which
provide better than 0.3 mm accuracy
Used with 2 or more optical sensors in the operating
room allows adequate triangulation to calculate 3
dimensional localisation

10. CONNECTION
Combined with the data from registration, these
connection allow real time tracking of
instrumentation with patients anatomy
A direct connection is also used with robotic arms
to compensate instantly for relative motion between
the bone and robotic arm, will automatically stop the
system if movement of greater than 2mm is detected

11. SMART TOOLS
 Smart tools are the standard or customised
orthopaedic instruments whose 3D
characteristics have been taught to the CAOS
system to allow their display on a navigation
system
 This involves attaching a tracking array to the
handle of an instrument to confirm a
connection between the handle and the system
 The working end of the instrument is then
placed onto a known location, and a
REGISTRATION between the handle and
working tip of the instrument is made, including
the offset and the orientation device

12. CLASSIFICATION OF COMPUTER ASSISTED
ORTHOPAEDIC SURGERY SYSTEMS

13. CLASSIFICATION OF COMPUTER ASSISTED ORTHOPAEDIC SURGERY
SYSTEMS

14. APPLICATION OF COMPUTERS AND NAVIGATION IN ORTHOPAEDICS
1. Navigation Arthroplasty of Hip and Knee
2. Spinal stabilisation
3. Trajectory Navigation- drill guide application (Tumour biopsies, drill
and entry point placements in trauma surgeries)
4. Osteotomies
5. Ligament reconstruction
6. Designing patient specific implants (PSI)
7. Computer assisted manufacturing (CAM) and Computer assisted
Designing (CAD) of implants, prosthesis

15. COMPONENTS OF NAVIGATION UNIT
Computer unit
Tracking unit
Tracker Mounting hardware

19. MODE OF OPERATION OF NAVIGATION
• The tracking base unit receives and integrates the
signals from position sensor and the trackers.
• The computer integrates the signals from the base unit
with fluoroscopic radiography or CT images and
instrument models (registration), creates one or more
views for display(visualisation)

20. MODE OF OPERATION OF NAVIGATION
• The Navigated images are updated in real
time by the computer as the instruments
and anatomy move
• The tool calibration unit is used to obtain
geometric data of surgical tools fitted with
trackers, such as tool tips offset
• These geometric data are used to create
the instruments model for display

21. TRACKING
• Tracking requires a position sensors and one or more trackers
• The position sensor determines the spatial location of the trackers
at any given point of time
• By attaching trackers to surgical tools and bone structures, their
relative spatial position can continuously be followed and updated
in the computer display
• Trackers are rigidly mounted on tools and bones tracker mounting
jigs, which are the mechanical jig similar to screws and clamps

22. • When fluoroscopic radiographic images are used for navigation, the
computer unit is also connected to a C-arm and imports images
acquired with it
• The C-arm is usually fitted with own tracker to determine its relative
location with respect to the tracked objects and imaged anatomy
• Types of tracking technologies are available for medical application
• OPTICALTRACKING – commonly used
• MAGNETICTRACKING
TRACKING

23. OPTICAL TRACKING
• In optical tracking, the position sensor consists of two or more
optical cameras that detect light emitted or reflected by markers
• Each camera measures the distance of the markers from the
camera
• Because the base distance between the optical camera is known,
the position of the marker with respect to the camera base line
can be computed by method known as TRIANGULATION

26. FUNCTIONING OF TRACKER- 3
DIMENSIONAL CAPTURE ANALYSIS

27. MAGNETIC TRACKING
• It works by measuring variations of general magnetic field
• The position sensor consists of a magnet that generates a
uniform magnetic field and a sensor that measures its
phase and intensity variation
• Magnetic trackers are susceptible to the presence of
ferromagnetic objects and other disturbances in the EM
fields

28. REGISTRATION
• Registration is a process of establishing a common reference frame
between objects and images
• It is a prerequisite for creating a reliable image of the intraoperative
situation to accurately show the relative locations of operative landmark
and the surgical tools on the navigation system
• It is achieved by activating the trackers placed accurately on precise bony
landmarks using a handled devise.
• Once activated, trackers are captured by the sensors and the registration
of bony landmarks are incorporated in to the computer to template the
relevant anatomy and coordinate with preoperative radiographs

30. TYPES OF NAVIGATION SYSTEM
• Image based navigation
• Passive navigation system/Kinematic systems
• Active or Robotic navigation systems

31. IMAGE BASED NAVIGATION SYSTEM
Fluoroscopy based systems: 2D imaging
3D fluoroscopy
CT based Navigation
MRI based systems

32. GENERATIONS OF IMAGE ACQUISITION
MODALITY
•1st
generation- preoperative CT based
•2nd
generation- Fluoroscopy based 2D and 3D system
•3rd
generation- Intraoperative CT based

33. • CT based image system are almost ideal preoperative images modality for the
needs of CAOS, they present the bony anatomy with high resolution and good
contrast and without any geometrical distortions
• MRI comparatively suffers from poor hard tissue representation and sometimes
considerable geometric distortions compared to CT, Hence MRI are not widely
used in orthopaedic navigation nowadays
• X ray fluoroscopy has geometrical imprecision due to the fact that they capture
only 2D projections of a 3D structure when compared to CT

34. CT BASED NAVIGATION
With CT imaging , 3D image is created by reconstruction of the
transverse planar images acquired in a systematic and sequential order
from a source- receiver assembly that rotates in a circular pattern
Because of its relatively high accuracy and the bone imaging
characteristics CT scans are very suitable for surgical navigation,
especially in orthopaedics

36. MAIN ADVANTAGES OF CT- BASED SYSTEMS OVER
CONVENTIONAL FLUOROSCOPY
1. They provide axial and spatial, real time multi-image visualisation of bony
anatomy and surgical tools
2. They significantly reduce the use of fluoroscopy in the operating room
Pre-operative planning is typically done in three orthogonal cross-sectional views
made through the CT scan

37. Pre operative
planning of the
acetabular implant

38. Preoperative
planning/templating
of the femoral stem
implant

39. PASSIVE NAVIGATION SYSTEMS
Passive navigation system utilizes a device calledTracker top
determine the spatial 3D positions and orientation of object in
real time
 Optical tracking by far most commonly used tracking
modality
It utilizes infrared light that is either actively emitted or
passively reflected from the tracked objects

41. STEPS IN NAVIGATION
Data acquisition
Surgical planning
Registration of patient anatomy in OR
Use computer based navigation algorithm
Guide implant placement

42. VISUALISATION
• It creates updated images that show the location
of moving objects with respect to the anatomy
• The Navigation images are created by merging the
preoperative and intraoperative images with the
tools and bone location information

44. VALIDATION
• Validation is the task of verifying that the images
and data used for intraoperative navigation closely
correspond to the clinical situation
• Its essential step otherwise the data can mislead
the surgeon and yield unwanted results
• It is performed both before the surgery starts and
at key points during the surgery

45. CAOS- TOTAL KNEE
ARTHROPLASTY
• Although mechanical instruementation in traditional TKA
has significantly increased the accuracy and reliability with
which knee reconstructions area performed, still the
errors in implant and limb alignment continue to occur,
even when the procedure is performed by experienced
surgeons
• Computer assisted surgical techniques have been
developed to address the inherent limitations of
mechanical intruementation

46. CURRENTLY USED NAVIGATION SYSTEM
FOR TOTAL KNEE ARTHROPLASTY
1. CT free BasedTotal knee Navigation
arthroplasty-Passive Navigation
2. CT based Navigation Arthroplasty
3. Robotic or Active Navigation Arthroplasty

47. PASSIVE NAVIGATION IN TKR
• Optical localisation using infrared light is currently the
most widely used method of communication
• The tracking markers attached to surgical instruements
and reference frames attached to bony landmarks have
light emitting diode(LED) which send out light pulses
top camera (optical localizer)
• The camera system to which the light is sent consists
of 2 planar or 3 linear charge couple devices(CCD)that
are rigidly mounted onto a solid housing

48. SURGICAL TECHNIQUE- PASSIVE NAVIGATION TKR
• The initial step is the placement of the reference spatial
frames(with tracker attached) in the distal femur and proximal
tibia
• These are placed outside of the skin incision in a position that
avoids injury to neurovascular structures and allows clear
visualisation of the trackers by the camera

50. • Once the skin incision is made and the distal femur and proximal
tibia are exposed, anatomic landmarks critical for CAS guided
navigation are located
• The centre of femur head is determined using kinematic
registeration technique
• The hip is circumducted in a path guided by the visual cues
displayed upon the computer screen
• The centres of the knee and ankle joint can be established by using
kinematic or surface registeration technique or a combination of
both

52. OTHER ANATOMICAL LANDMARKS REGISTERED WITH A HANDHELD
CAS PROBE
The distal femur
The posterior condyle line
The anterior femoral cortex
The transepicondylar axis
The medial and lateral tibial articular surfaces

55. • Femoral and tibial stem
preparation done
• The CAS determination of
femoral implant size and
anterior and posterior
placement can be made using
anterior and posterior
referencing technique

56. Resection of distal femur
Computer interface indicating position
of distal femoral cutting block with
regard to frontal 0 degrees and sagittal 3
degrees anterior slope mechanical
alignment and depth of resection 9mm

57. Resection of proximal tibia:
Computer interface indicating position of proximal tibial
cutting block with regard to frontal 1degree varus and sagittal 0
degree mechanical alignment and depth from least involved tibial
surface 9mm

58. • Once the femoral and tibial resections are completed, a trial reduction is carried
out
• The polyethylene inserts that best, balances the knee in flexion and extension is
selected
• The navigation system is used to measure the final alignment of the extremity,
the amount of medial-lateral laxity in extension and flexion and the final range of
motion
• After the actual implants are inserted, the navigation system is used to measure
the final frontal and sagittal alignment of the extremity, the final medial-lateral
stability and final range of motion

62. CAOS IN HIP ARTHROPLASTY

63. • CAOS in Total hip arthroplasty is divided into using
Preoperative CT based(image based navigation) or
intraoperative mapping of osseous anatomical landmarks
on a generic model of pelvis(imageless navigation)
• CAOS in Total hip Arthroplasty improves accuracy in
achieving the planned acetabular cup positioning compared
to conventionalTHA
• Improves Precision and reduces outliers in restoring the
planned centre of hip rotation compared to conventional
THA

64. • Computer Navigation provides patient specific anatomical data with
recommendations for bone resection and optimal implant
positioning
• Robotic THA uses computer software to convert anatomical
information into a virtual patient specific 3D reconstruction of the
pelvis, which operating surgeon can calculate and plan optimal
implant positioning
• Depending on the degree of the control that the robotic device
provides the operating surgeons, robotic system classified as either
fully active or semi active

65. STAGES OF ROBOTIC THR
1. Preoperative CT scans of pelvis and proximal femur are
used to create a patient specific virtual 3D model of the
native hip anatomy.
This model accounts for pelvic orientation in
the axial, sagittal and coronal planes, which
enables accurate assessment and planning for
restoration of hip biomechanics

66. 2. The surgeon uses this virtual 3D reconstruction to template
the optimal implant positions and sizes for achieving desired
bone coverage, restoration of hip biomechanics, component
version, component inclination and leg-length correction.
Software calculates the depth of acetabular reaming, femoral
osteotomy site and angle and component positioning
STAGES OF ROBOTIC THR

67. 3. The surgeon intraoperatively maps the osseous anatomy of
acetabulum and proximal femur to establish bone geometry and
confirm pelvic position prior to bone resection
4. A robotic device is used to execute the planned bone resection and
guide final implant positioning with live onscreen changes in bone
coverage, implant inclination, implant version, offset any impingement
and leg length correction displayed throughout the procedure
STAGES OF ROBOTIC THR

73. COMPLICATIONS AND TECHNICAL PITFALLS DURING
NAVIGATION PROCEDURE
Loss of line of sight:
An obstructed view between the optical camera and the trackers
at all times is the basic requirement of optical navigation
Loss of line of sight occurs when the view between the optical
camera and one or more of the trackers is obstructed by the
surgeon or another member of surgical team, the patients body,
the fluoroscopic c arm or any other object in the vicinity of the
surgical field

74. Tool deliberation It occurs when the geometric data of the
tracked tool do not maych its actual geometry
Navigation image inaccuracy: inaccuracy of navigation images
is the mismatch between the displayed images and intraoperative
situation
Inaccuracy is the result of errors in the registration chain
COMPLICATIONS AND TECHNICAL PITFALLS DURING NAVIGATION
PROCEDURE

75. System robustness issues
Robustness is the ability of a system to perform its intended tasks
with a minimum number of failures over time
The more the robust the system, the more acceptable it will be to
the surgeon. Robustness depends on both software and hardware
components
COMPLICATIONS AND TECHNICAL PITFALLS DURING NAVIGATION
PROCEDURE

76. Shifting of the dynamic reference frame/Tracker positioning
Maintaining the rigid attachment between the bone tracker and the bone,
throughout the surgery is essential in order to guarantee registration accuracy
Shifting is usually the result of bone fixation loosening, poor jig fixation, or
unintentionally pushing or hitting the tracker and its monitoring jig
COMPLICATIONS AND TECHNICAL PITFALLS DURING NAVIGATION
PROCEDURE

77. HYBRID SYSTEMS
NAVIGATION +
ROBOT
It is a hand held Robot
showing here

78. TYPES OF ROBOTIC SURGERY SYSTEMS
• Haptic (Tactile or surgeon guided)
• Autonomous system
Haptic system requires surgeon’s continuous input for efficiently performing and
completing surgery. Surgeon uses or drives Robot to perform an operation.
While,Autonomous system differ from haptic system by having more
independency.After the operative site is approached by the surgeon, he sets up
the machine and then engages the Robot, which completes the remaining task
without the help of a surgeon

79. CATEGORIES OF CAOS
• ACTIVE SYSTEM: in this entire procedure can be carried out
by robot with guidance of surgeon or independently.
• PASSIVE SYSTEM: in which the robot or computerized
program aids the surgeon in completing surgical procedure
Note: Regardless of active or passive system, CAOS requires a
mode of navigation to accurately carry out the procedure

80. ADVANTAGES OF ROBOTIC SURGERY
Minimal invasive surgery(MIS) is possible
Implants can be placed more accurately
Radiologically, improved alignment of
extremities

81. HAPTIC ROBOTIC SYSTEM
• ROBOTIC ARM INTERACTIVE ORTHOPEDIC
SYSTEM(RIO,MAKO SURGICAL CORPORATION.)
• Its commercially available tactile system for
Unicondylar Knee Replacement(UKR)
• It is an tactile system so surgeons participation is
must to complete the UKR
• Preoperatively, CT scan of knee is required with
which 3D computer model of the knee is
prepared which forms the basis of planning

82. • Based on this, surgeon will mark the bony surfaces of femur and
tibia during operation
• Surgeon merges the preoperative model into active anatomy of
the knee.
• After taking the knee through full range of motion, the flexion
extension gap assessed, component size and implant placement
finalized and a cutting zone is created for the Robot.
• Preoperative planning and templating process forms the base for
the systems algorithm
• By viewing the 3D model of the knee on the monitor, the
surgeon accurately manipulates the burr and resects the bone.

83. • Forced controlled tip of the rotating burr cannot resect the bone
outside the predefined cutting space.
• The safety system automatically stops the Burr when goes beyond
the cutting zone
Other Robotic systems for UKR is ACROBOT SYSTEM
ACROBOT SYSTEM MAKO RIO

84. AUTONOMUS ROBOTIC SYSTEMS
They differ from Tactile system by their independency, It do not require surgeon’s
assistance
 Defined on the preset program they carry on and complete the surgery on their own
ROBODOC(California): It is autonomus robotic system developed in 1980 and taken
into surgical practice in 1992 for THA.
Other examples of AUTONOMUS ROBOTIC SYSTEM
MINI BONE ATTACHED ROBOTIC SYSTEM(MBARS):Pittsburgh, Pensylvania
Praxiteles: developed in France

85. MAKOTHRVIDEO

86. MAKO TKR VIDEO

87. ROBOTIC SURGHERY:PITFALLS AND LIMITATIONS
The setup required for performing robotic surgery is a expensive
It constantly requires software upgradations and caliberations, making it
more expensive
Superiority and cost efficiency of robotic surgery in routine are yet to be
demonstrated by long term outcome studies
Robots can well identify the Bony anatomy, but itself cannot manage soft
tissue dissection
Currently, high quality level 1 studies including randomized control trails
are not available for the use of robotic surgery in clinical practice
The autonomous robotic system ROBODOC fell into disrepute because it
was associated with increased risk of blood loss, infection and neurological
damage perhaps increased rate of litigation

88. TELESURGERY
• Using robotics and/or other computer assisted devices
experienced surgeons can supervise, assist or perform surgical
procedures at remote location
• The 1st
telesurgery procedure was reported in 2001 whwn
surgeons from NewYork operated on 68 year lady in
Strasbourg, France for cholecystectomy by remotely
manipulating robotic tools
• In orthopaedics, telesurgery is not yet well developed

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90. Thank you