Caos and robotic surgeries

Computer Assisted Orthopaedic Surgery (CAOS)

&Robotic Surgeries.

Dr. S.K.Venkatesh Gupta, M.S,M.Ch(Ortho)

Professor & HODMAMATA MEDICAL

COLLEGE,KHAMMAM,AP,INDIA

Dr. Y. Ranjith Kumar

Post graduate

drranjithkumar@gmail.com

Computer-assisted orthopaedic surgery is defined as the use of computers and robotic technology to assist the orthopaedician in providing musculoskeletal care.

This technology includes; ◦ Pre-operative planners, ◦ Intraoperative navigation equipment, ◦ Smart tools,◦ Remote surgery technologies.

INTRODUCTION

Computers augment orthopaedic surgery by taking advantage of these fundamental characteristics

geometric precision, reproducibility, perfect “memory,” lack of fatigue.

The synergy of these characteristics combined with an orthopaedic surgeon’s inherent judgment, experience, adaptability, and knowledge is crucial to the success of computer-assisted orthopaedics.

1906 – Clark and Horsley first described principles and designs for stereotaxis.

1974 – Schlondorff and co-workers first used these principles of stereotaxis in navigational calculations on bone.

1980 – CAM & CAD designs using CT scan templates for mega prosthesis was started.

1985 – First Robotic surgery done for a brain biopsy. 2000 – Computer assisted spine surgery was done at

Oklahama State university. 2002 - The first CT-based systems in trauma for percutaneous

iliosacral screw insertion and for intra-medullary nailing of femoral shaft fractures.

History

Computer-assisted orthopaedic surgery (CAOS) or image guided orthopaedic surgery (IGOS) is an area in which machine capability is coupled with human judgment and skills to perform a task better than either could do alone.

Robotic surgery is a semi-autonomous procedure performed by a robotic arm under direct or indirect control of surgeon.

DEFINITIONS

REGISTRATION

It matches the virtual world of images to the

real world of the patient and operating room

environment.

Registration refers to the correlation between CT or

fluoroscopic images and a fixed point on the patient’s

anatomy.

Connection is the actual or virtual link between the patient and the CAOS system.

Referred to as TRACKERS.

The most common type of connection is via light emitting diode (LED) arrays placed on the instruments, which provide better than 0.3 mm accuracy.

Used with 2 or more optical sensors in the operating room allows adequate triangulation to calculate a three dimentional (3D) localization.

CONNECTION :

Combined with the data from the registration, these connections allow real time tracking of instrumentation with the patient’s anatomy.

A direct connection is also used with robotic arms to compensate instantly for relative motion between the bone and robotic arm, stopping the system if movement of greater than 2 mm is detected.

Surgical navigation is the intra-operative display

of the operative field with the location of a probe or

instrument overlaid onto any image such as

fluoroscopic data, an MRI, or CT scan.

Surgical navigation :

Smart tools are standard or customized 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 form 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 orientation of the device.

SMART TOOLS :

S.No CATEGORY Sub Category MECHANISM

1. NAVIGATION Image FreeImage Based(pre-op)Image Based(Intra-op)

Passively acts as Position tracking devicesand information systems, sub-classifiedbased on imaging needs

2. ROBOTICS IndustrialHand-heldBone-mounted

Actively perform surgical actions, subclassifiedbased on ergonomics

3. HYBRIDTECHNIQUES

Image FreeImage Based

Combine features of robotic and navigation,sub-classified based on imaging needs

CLASSIFICATION OF COMPUTER ASSISTED ORTHOPAEDIC SURGERY SYSTEMS:

S.No

CATEGORY Sub Category MECHANISM

4. TEMPLATING GuideTool

Both are image based

Provide guidance and/or tooling, sub-classifiedbased on the mechanism of action ofthe templates

5. SIMULATION

( EXAMPLES :ROM simulators Knee arthroscopy simulatorsImage overlay)

Planning simulatorsVirtual realityAugmented reality

Improve visualization through intuitiveuser interfaces ― interactive animation,sub-classified based on the way data aremanipulated

6. TELESURGERY

(UNDER DEVELOPMENT)

TelepresenceTelementoring

Allows the surgeon to remotely operate ormentor other surgeons

Facilitates minimal invasive surgery (MIS) by reducing soft tissue damage, thus shortening the postoperative rehabilitation process.

Improves the accuracy of fracture reduction and implant placement compared with that obtained with conventional methods and reduces outcome variability

Significantly reduces radiation exposure to both the patient and the surgeon

Creates a powerful educational and quality control tool

ADVANTAGES of CAOS

1. Trajectory navigation—drill guide applications (hip and pelvic fractures; Tumour biopsies; pedicle screw placements; drill and entry point placements in trauma surgeries)

2. Fracture reduction and assesment.

3. Intra-articular fracture fixation.

4. Localization of bone lesions or removal of surgical hardware and shrapnel.

5. Navigation arthroplasty of Hip and Knee.

6. Spinal stabilisation.

Applications of Computers & Navigation in Orthopaedics

7. Individualizing tunnel placement in ligament surgery,8. Open wedge osteotomy9. ligament reconstruction, and balancing and tensioning

of the ligaments during the procedure.10. Surgical technical skills Training.11. Bone morphing – in implant designing and sizing

templates for new implants taking average anthropometric cadaveric data.

12. Designing Patient Specific implants (PSI).13. CAM ( Computer Assisted Manufacturing) and CAD

( Computer assisted Designing) of Implants, prosthesis and megaprosthesis.

◦Computer Unit,

◦Tracking Unit,

◦Tracker Mounting Hardware.

Components of a NAVIGATION UNIT :

COMPUTER UNIT

TRACKING UNIT

TRACKING MOUNTING

The tracking base unit receives and integrates the signals from the position sensor and the trackers.

The computer integrates the signals from the base unit with fluoroscopic radiography or CT images and instrument models (registration), and creates one or more views for display (visualization).

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 the tool tip's offset.

These geometric data are used to create the instrument model for display.

Tracking requires a position sensor and one or more trackers.

The position sensor determines the spatial location of the trackers at any given moment 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 with tracker mounting jigs, which are mechanical jigs

similar to screws and clamps.

TRACKING

When fluoroscopic radiography 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 its own tracker to determine its relative location with respect to the tracked objects and imaged anatomy.

Currently, two types of tracking technologies are available for medical applications:◦Optical tracking.◦Magnetic Tracking.

optical being by far the most commonly used .

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 cameras is known, the position of the marker with respect to the camera's base line can be computed by a method known as triangulation.

Optical Tracking

Each surgical tool is equipped with passive markers – white dots are the markers.

Functioning of a tracker – 3 dimensional capture analysis.

Magnetic tracking works by measuring variations of generated magnetic fields.

The position sensor consists of a magnet that generates a uniform magnetic field and a sensor that measures its phase and intensity variations.

Magnetic Tracking

In EM tracking the emitting coil emits an electromagnetic field that induces the electricity current in the receiving coil.

The position of the receiving coil is detected by measuring the induced current and solving the EM field equation for spatial variables.

This method does not require the line of sight between the localizer and its target and can therefore enable better operating room ergonomics.

Magnetic trackers are susceptible to the presence of ferromagnetic objects and other disturbances in the EM field.

Registration is the 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 the operative landmarks and the surgical tools on the navigation screen.

Registration :

Registration is achieved by activating the trackers placed accurately on precise bony landmarks using a handheld device.

Once activated, trackers are captured by the sensors and the registration of the bony landmarks are incorporated in to the computer to template the relevant anatomy and coordinate with preoperative radiographs.

Visualization 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.

VISUALIZATION

Validation is the task of verifying that the images and data used for intraoperative navigation closely correspond to the clinical situation.

It is essential to verify and quantify the correlation; otherwise the data can mislead the surgeon and yield unwanted results.

Validation is an integral part of the navigation surgical protocol.

It is performed both before the surgery starts and at key points during the surgery.

VALIDATION

Image Based NAVIGATION

PASSIVE NAVIGATION SYSTEMS / KINEMATIC SYSTEMS.

ACTIVE or ROBOTIC NAVIGATION SYSTEM – HYBRID SYSTEMS

TYPES OF NAVIGATION SYSTEMS :

Fluoroscopy-Based Systems – 2D Imaging.

Three-Dimensional Fluoroscopy : by taking about 100 fluoroscopic radiography images at 1-degree intervals with a motorized isocentric C-arm and translating in to a 3D image.

CT based Navigation

Ultrasound based systems helpful in identifying soft tissues, ligaments and vasculature

MRI based systems – currently under development.

 Image Based NAVIGATION :

Passive navigation systems utilizing a device called tracker to determine the spatial 3D positions and orientations of objects in real time.

Optical tracking is by far the most commonly used tracking modality.

It utilizes infrared light that is either actively emitted or passively reflected from the tracked objects.

PASSIVE NAVIGATION SYSTEMS / KINEMATIC SYSTEMS :

The robotic system in conjunction with the position sensors attached to the individual joints of the robotic arm is used to precisely position mounted surgical tools to perform specific tasks as part of the therapeutic treatment.

ACTIVE or ROBOTIC NAVIGATION SYSTEM /HYBRID SYSTEM

CTs are an almost ideal preoperative image modality for the needs of CAOS: they present the bony anatomy with high resolution and good contrast and without any geometrical distortions.

Magnetic Resonance Imaging (MRI) in contrast suffers from poor hard tissue representation and sometimes considerable geometric distortions compared to CT. Hence, MRIs are not widely used in orthopaedic navigation nowadays.

X-ray flouroscopy has geometrical imprecision due to the fact that they capture only a two-dimensional (2D) projection of a three-dimensional (3D) structure when compared to a CT scan.

With CT technology, three-dimensional image is created by a 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.

CT BASED NAVIGATION

The two main advantages of CT-based systems over conventional fluoroscopy are :

◦1) They provide axial and spatial, real-time multi-image visualization 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.

Pre-operative planning of the acetabular implant.

Pre-operative planning/templating of the femoral stem implant.

After the landmarks are automatically detected in the planner, the alignment of implant components can be uniquely defined.

The surgeon selects the implant components from the database and places them in a desired position and orientation, using both cross-sectional CT views and 3D surface models.

In the final stage, the virtual replacement joint is assembled and tested for the range of motion simulation.

The range of motion analysis is performed for any desired leg motion path, to test the impingement limits of that motion for that implant for that patient.

Both prosthetic and bone impingent limits are detected.

The effects of the change of any relevant parameter (orientation, size, position, pelvic flexion) on ROM and on component offset and leg length can be examined in real time, helping the surgeon in optimizing the plan.

The implants orientation can be modified, or alternative components can be selected, so that the safe range of motion is maximized, and the leg length change is properly considered.

Pre-operative analysis of implant – Testing range of motion simulation. a) Neutral position b) joint in Internal rotation & flexion.

Red dot indicates the impingement point.

Typical indications for direct 2D navigation:◦ Long bones: Insertion of intramedullary nails including

distal locking.

◦ Corrective osteotomy of long bones.

◦ Hip endoprosthetics, especially acetabulum and shaft navigation.

◦ Insertion of screws in the femoral neck

Flouroscopy based Navigation

Positioning reference frames with trackers during a hip surgery and registering them with a hand held device.

Image seen on computer display during insertion of the cannulated screws demonstrates three screw trajectories. The length and diameter of the wires are measured and displayed on the lower part of the display.

In Pedicle screw fixation using fluoroscopy guided navigation, two single X-ray views from A-P and lateral positions are acquired within the area that has to be operated on (here a lumbar vertebra)

All the dots refer to the radio opaque elements on the C-arm plate. These dots on the image serve as reference points in the

2D navigation system.

A computer-generated projection of the surgeon's surgical tool is displayed in each view. A real-time navigation in several views is possible simultaneously.

The surgical instruments are navigated and thus placement of the pedicle screws and positioning can be tracked accurately.

Typical indications for direct 3D navigation:◦Fractures which include the artcular region: upper

and lower limbs (elbow, distal radius, scaphoid bone, knee, distal tibia, calcaneus, talus, etc.), and acetabulum.

◦Spine: positioning of pedicle screws in the lumbar and thoracic spine, cervical spine fixation.

◦Pelvis: fractures, insertion of screws in the iliosacral region, osteotomies

Screw Osteosynthesis in Tibial Plateau fractures – 3D navigation by C - Arm

Although mechanical instrumentation has significantly increased the accuracy and reliability with which knee reconstructions are performed, errors in implant and limb alignment continue to occur, even when the procedures are performed by experienced surgeons.

The accuracy with which these procedures are performed using manual instrumentation is dependent upon the knowledge and experience of the surgeon and the frequency with which the surgeon performs the procedures.

Computer-assisted surgical techniques have been developed to address the inherent limitations of mechanical instrumentation

CAOS – Total Knee Arthroplasty

Navigation systems for total knee arthroplasty currently used are

1. CT-Free-Based Total Knee Navigation Arthroplasty – Passive Navigation

2. CT based Navigation arthroplasty

3. Robotic or active navigation arthroplasty.

Optical localization using infra-red light is currently the most widely used method of communication.

The tracking markers attached to surgical instruments and reference frames attached to bony landmarks have light emitting diodes (LED) which send out light pulses to a camera (optical localizer).

The camera system to which the light is sent consists of 2 planar or 3 linear charge couples devices (CCD) that are rigidly mounted onto a solid housing.

PASSIVE NAVIGATION in 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 visualization of the trackers by the camera.

Surgical Technique – Passive Navigation TKR

Once the skin incision is made and the distal femur and proximal tibia are exposed, the anatomic landmarks critical for CAS guided navigation are located.

The centre of the femoral head is determined using a kinematic registration 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

using kinematic or surface registration techniques or a combination of both.

Computer interfaces illustrating motion necessary to acquireadequate kinematic information to establishlocation of the center of: a,b hip joint, c,d knee joint, e,f ankle joint

The other anatomic landmarks registered with a hand held CAS probe are:◦ the distal femur. ◦ the posterior condylar line .◦ the anterior femoral cortex. ◦ the epicondylar axis.◦ the medial and lateral tibial articular surfaces.

REGISTRATION

Mechanical Axis assesment intraoperatively by tracker detection

Femoral and tibial stem preparations are done. The CAS determination of femoral implant size and

anterior-posterior placement can be made using either anterior or posterior referencing techniques.

Anterior cortical reference beingestablished by using computer guidance

Resection of distal femur. a 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 (9 mm).

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

Checking of the ligament balancing

Once the femoral and tibial resections are completed, a trial reduction is carried out.

The polyethylene insert 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.

The system can be used to guide the release of tight soft tissues medially, laterally and posteriorly if this is necessary to establish a balanced, well-aligned knee.

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.

Final frontal and sagittal alignment depicted on computer screen correlates with post-operative standing long x-ray.

Due to problems including fixation of cumbersome reference frames and trackers, signal acquisition, soft tissue trauma, and operative constraints, a technology using a signal that does not require line-of-sight of detection was desirable.

An electromagnetic computer-assisted surgery (EM-CAS) system has this capability.

Electromagnetic Passsive Navigation Surgery.

EM magnetic wires are less cumbersome and act as source of input to the computer

Freshening up unsatisfactory cuts to perfect alignment iseasily done without cumbersome correction jigs. The surgeon can maintain constant updates of correction progress without losing navigational signals when the surgeon or assistants are inthe way of the receiver

Criteria for anatomical placement of the tibial tunnel: The tibial exit point on the tibial plateau should

satisfy the following criteria:◦ 7 mm distance from the anterior margin of the posterior

Cruciate ligament with the knee joint in app. 80° flexion,

◦ Center between the anterior horn of the lateral meniscus and the spine of the medial tibial tubercle,

◦ 44% of the coronary width of the tibial plateau beginning from the most medial position.

Navigation in ACL reconstruction :

The femoral entry point in the notch should satisfythe following criteria:

◦3–5 mm distance from the posterior margin of the fossa.

◦ Placement of tunnel in Left knee: 12.30–01.30 o’clock position, Right knee: 10.30–11.30 o’clock position

Notch topography Is obtained.

On the tibial side, the precise location of the tip of the aimer is identified in relation to the PCL, lateral meniscus, medial tibial eminence, and the medial and lateral walls and roof of the intercondylar notch.

The femoral tunnel is identified with respect to distance from the over-the-top position and the

clock-face location.

Intra-operatively drawer test aquisition can be madeDisplay of the medial and lateral translation laxity and rotation during a drawer test can be done. The stability for each compartment can be assessed in real-time.

The blue circles correspond to the insertion points of the tunnels – the red area on the right image of the femur shows the potential impingement area between the graft and the notch for the selected centre of the tunnels.

Fluoroscopy based ACL reconstruction

It is more accurate and has an advantage of elimination of registration needed for tracking navigation system.

Fluoroscopy based navigation showing entry point for tunnel placementsGreen line shows the trajectory path and the pink line show the guide wire.

Computer assisted HIP ARTHROPLASTY

Acetabular reamer navigation

Acetabular cup impaction - Navigation

Stem navigation using the fluoroscopic application. The surgeon gains additional information about the leg length, offset and varus/valgus alignment

Hip Resurfacing Arthroplasty

Planning screen for screw position centrally within the femoral neck

Registration of bone and anatomy

Alignment of head and positioning with trial simulator for sizing of implant and impingement checked with range of motion simulator.

Pre-op planning, intra op navigation and post op x ray

The aims of a high tibial osteotomy are:◦correction of the joint deformity to release the

loading of the medial joint compartment,◦pain-reduction and improvement of the joint-

function,◦possibility of a biological joint healing with

additional intra-articular procedures to enhance regeneration of the joint-surface.

HIGH TIBIAL OSTEOTOMY

The principle of the high tibial osteotomy seems to be easy, but for this operation precise planning and an exact intra-operative transformation of the planning is required.

The failure analysis leads to the assumption, that the results of high tibial osteotomies could be improved by means of a navigation-system.

lateral tibial metaphysis is preparated for the osteotomy and the first reference marker (rigid body) is fixed 10 cm below the joint space.

An additional marker is fixated at the distal femur. By moving of hip, knee and ankle-joint the joint centers and the leg-axis is determined exactly by the system.

Closed wedge technique :

By means of the navigation-system the saw-jig for the first, horizontal osteotomy can be positioned exactly according to the preoperative planning.

Pre-operative X ray. Post – operative x ray at 6 months showing wedge closed with conventry staples.

During the cutting procedure the positioning of the sawblade and the distance between the tip of the saw-blade and the medial cortex of the tibia can be controlled on the monitor.

The exact cutting angle of the saw blade is also documented on the monitor in real time.

After removal of the lateral based bone-wedge the osteosynthesis can be performed with Coventry staples or a bone plate.

The main problem with transpedicular screws is the proximity of the spinal cord in the thoracic area and the proximity to the nerve roots at the lumbar spine with the possibility of neurological complications as a consequence of screw mal-placement especially medial-screw mal-placement. using conventional pedicle screw-insertion techniques.

CAOS overcomes this complication.

CAOS in Spine Surgery

Pedicle screw fixation Scoliosis correction surgeries Spinal Tumour Biopsies

Indications in Spinal surgery :

Reference arc is attached to aspinous process

Determination of the screw-entrypoint with the pointer

Preparation of the pedicel with a trackable tool

Placement of the screw with a trackable screwdriver to know the angulation of screw and alignment and length.

Red : actual position of the pointer; green: simulated screw length and diameter to acertain the size of screw to fit in to pedicle in both AP and lateral planes.

Case of Kyphoscoliosis

Three dimensional reconstruction of deformity and BLUE Shaded portion showing planned site of posterior vertebrectomy.

Post operative pedicle screw fixation.

CAOS in tumours and metastatic lesions in Spine and Pelvis

Depending on the extent of the disease, the main goals of tumour surgery of the spine are tumour reduction, decompression of the neural structures, and stable fixation of a malignancy-induced destabilized spine.

Another disadvantage in standard spine tumour surgery is that the extension of the tumour cannot be accurately determined intra-operatively.

Pre-op CT Image of L5 vertebral body tumour under evaluation.

Navigation used in biopsy of tumour

Green Spot – Target of biopsy site

Line – Representing the trajectory of biopsy needle

Radiation Reduction : An advantage of fluoroscopy based navigation is the

reduction of radiation to both the patient and the surgical team.

One minute of intraoperative fluoroscopy of the pelvis is equivalent to about 40 mSv (milli Sievert) of radiation, 250 radiographs of the chest, or one pelvic CT scan. Thus, the maximum allowable amount of radiation to the hands and eyes is reached after 50 cases.

A prospective randomized study of navigated versus standard distal locking of intra-medullary nails showed significant radiation reduction when using navigation.

CAOS in Trauma

Navigation is helpful in the following situations of trauma management :◦ Articular fractures◦ Interlocking nails for beginners and distal locking◦ Percutaneous Pelvic and acetabular fracture fixation with

screws.◦ Calcaneal fractures◦ Implant simulation and sizing

Percutaneous Ilio-sacral screw fixation.

The pink line shows the actual drill guide axis and tip;the greenone its predicted trajectory. The diameterand extension of the trajectory line areshown at the centre bottom of the screen.

The safe zone for screw placement is narrow due to the presence of nearby nerve structures.

A classical example is the placement of an anterior column screw for the transverse component of an acetabular fracture via a posterior approach.

Their placement requires repeated use of intra-operative fluoroscopy, which can be totally avoided with navigation.

The starting point can be determined with a tracked cannulated drill guide by choosing an entry point and observing the planned trajectory on the screen.

Very helpful for beginners.

Faster and more accurate placement of nails.

Aids in Reduction assesment.

Interlocking Nails

Determining an implant position after fracture reduction by positioning an implant template on post reduction fluoroscopic images particularly in trochanteric fractures

Fracture reduction. computer screen showing the proximal (top, green line) and the distal (bottom, red line) fragment axes.

Foot and Ankle trauma

A case of C-armbased correction of hindfoot deformity after mal-unitedcalcaneus fracture.

Fixation of a wireless Dynamic Reference Base(DRB) to the talar neck and the tuber calcanei

1. Management of Old and intra-articular calcaneal and talus

fractures.

2. Hallux valgus deformity correction.

Antero-posterior and lateral digitalradiographic images were obtained, and the data were transferred tothe navigation device. During the correction, the angle motion and translational motion between the bones or fragments in all degrees of freedom were displayed on the screen.Bohlers angle calculated and assesment of intraarticular reduction done.

Improve visualization through intuitive user interfaces ― interactive animation .

ROM simulators Knee arthroscopy simulators Planning simulators Virtual reality Augmented reality

4. SIMULATORS :

Femoro-acetabular impingement syndrome – Computer assisted simulation

Normal hip with sufficient clearance for range of motion

Pincer impingement:

The overcovering area of the acetabular rim (OA) leads to an early contact of the femoral head withthe acetabulum.

Cam impingement: The aspherical part(AP) of the femoral head is jammed into the acetabulum resulting intears of the labrum (L) and considerable pre-arthrotic damage of thefemoral and the acetabular cartilage

With navigation by trackers and dynamic hip movement, the area of impingement can be marked and assesed by simulator.

the impingement zones are detected both for the femur and the acetabulum with localization on the virtual three-dimensional model

A) Quantification of the acetabular segment to be trimmed is achieved with a superimposition imaging system and the width of theAcetabular Rim to be resected is measured in mm (x).

B) For the femur, head-neck offset is created by millimetre-stepwise removing of the non-spherical femoral neck portion (y) inthe antero-superior aspect of the femoral head-neck offset

Arthroscopic simulators are commercially available that gives hands on learning experience in using the arthroscopic portals for trainees.

The simulation exercises are designed for all the pathologic conditions and gives good amount experience for trainee surgeons to use and acclamatize to the instrumentation.

Computer assisted technical skill training of orthopaedic procedures.

Knee simulator for arthroscopy

Augmented reality (AR) is the combination of real world and computer-generated data.

In orthopaedic surgery, this computer display technique can superimpose computer images over the surgeons’ direct view of the real anatomy.

Currently under research to implement in arthroscopic surgeries.

AUGMENTED REALITY

Using AR, endoscopic camera view, visualization of instrument position can be visualized in their actual location overlaid into a stereoscopic real time image in front of the surgeon between him and operative field.

For any kind of reduction or correction at the foot and ankle an immediate biomechanical assessment of the reduction result would be desirable.

Normally, analyzing the bones and fracture reduction radiographically allows conclusions about the biomechanics of the foot by surgeons experience.

Pedography is considered to be more effective for the analysis of the biomechanics of the foot.

Intraoperative pedography

Computer-Assisted Ligament Balancing of the Femoro-Tibial Joint Using Pressure Sensors in TKR

Pressure-sensing device is sandwiched between the tibial trial insert and a protective low molecular weight polyethylene covering.

PATIENT SPECIFIC IMPLANTS (PSI)

Loss of line-of-sight : An unobstructed 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 the surgical team, the patient's body, the fluoroscopy C-arm, the overhead lamps, or any other object in the vicinity of the surgical field.

Complications and Technical Pit falls during Navigation Procedures.

Tool decalibration Tool decalibration occurs when the geometric data of the tracked tool do not match its actual geometry.

Navigation image inaccuracy Inaccuracy of navigation images is the mismatch between the displayed images and the intraoperative situation.

The inaccuracy is the result of errors in the registration chain.

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 robust the system, the more acceptable it will be to the surgeon. Robustness depends on both software and hardware components.

Shift of the dynamic reference frame/ Tracker positioning :

Maintaining a 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 mounting jig.

HYBRID SYSTEMS

Free Hand Sculptor (a handheldrobot)

NAVIGATION+

ROBOT

The term “Robot” is derived from the Polish word, “robota”, which means, “forced labour” and is used to describe a machine that carries out multiple tasks automatically or with a minimum of external impulse, especially one that .is programmable

Robotic surgeries

Medical Robotics

Principle : Computer-enhanced surgical dexterity through telemanipulation

Surgeon’s Console

• 3D visual immersion

• Eye - hand alignment

Eye - Hand Alignment

• Image of instruments appears in place of hands

• Hand motions replicated

inside patient

• Scaled and indexed motion

• Camera and cautery control

Two systems for Robotic Surgery exist: 1)Autonomous 2) Haptic (Tactile) System

In autonomous systems, the surgeon performs the approach, sets up the machine and then engages the robot to complete the surgery without the surgeons help .

Haptic systems allow the surgeon to drive, or use the robot to perform the operation

Constant input of the surgeon is mandatory for efficient functioning of the system

Advantages of Robotic Surgery include:-

◦Ability to perform MIS

◦Improved accuracy of implant placement

◦Improved radiological alignment of extremities

Commercially available tactile systems for Unicondylar knee replacement: Robotic Arm Interactive Orthopaedic System (RIO, Mako Surgical Corp.)

Uses preoperative CT scans to generate 3D computer model of the knee

Helps for preoperative planning Surgeon will intraoperatively mark the bony surfaces

of the femur and tibia allowing the preoperative model to be merged into the active anatomy of the knee

HAPTIC ROBOTIC SYSTEMS:

The knee is taken through a full range of motion, the flexion-extension gaps assessed, component size and implant placement finalized and a cutting zone is created for the robot.

The system’s algorithm is wholly based on the preoperative planning and templating.

While manipulating the burr, for resection of bone, the surgeon can view the 3D model on the monitor.

Resection of bone is confined to the predefined cutting space on the forced controlled tip of the rotating burr.

In any case if the surgeons goes beyond the cutting zone, the safety system automatically stops the burr.

ACROBOT System –

Unicompartmental knee arthroplasty.

Bone mounted Robots

MBARS≪ robotpositioned for patello-femoral arthroplasty

MINARO≪ robot positioned for cement removal in revisionTHA

Cobb et al..used Acrobot systems (UK), and compared Robot assisted UKR versus Conventional UKR

They found that in patients who underwent Robot assisted UKR, there were better AKS scores(American Knee Society) , increased operating time,  tibiofemoral alignment and implant positioning within 2 degree of preoperative plan in all patients

In the conventional UKR group, only 40% of patients achieved tibiofemoral alignment within 2 degree of the preplanned position

Acrobot Systems

Autonomous robotic systems complete the surgery without assistance of a surgeon

Though the robot operated independently, the surgeon is in control of an emergency shut-off switched

ROBODOC was such a system that was developed in the 1980s and was introduced into surgical practice in 1992 (Curexo Technology, California).

AUTONOMOUS ROBOTIC SYSTEMS

ROBODOC was very popular in Germany with many trials conducted in THA demonstrating good component positioning, but soon fell into disrepute amidst safety concerns

A hybrid system has been developed in Carnegie Mellon University, Pittsburgh, Pennsylvania. In this system the Mini Bone Attached Robotic System(MBARS), mounts on to the femur and completes the bony resection in TKR.

Praxiteles (Praxim, France) is another similar robotic system developed in France.

The setup required for performing robotic surgery is expensive.

Also contant software upgradations and calibrations will add to the cost. It may still be cost efficient in high volume institutions

Though proposed advantages like short hospital stay, less blood loss, greater accuracy are present, long term outcomes studies are necessary to demonstrate superiority and cost efficiency of Robotic surgery in routine practice

Robots, can identify bony anatomy well. But cannot manage soft tissue dissection by it self for orthopaedic practise.

ROBOTIC Surgery: Pitfalls

The autonomous robotic system, the ROBODOC fell into disrepute because it was associated with increased risk of infection, blood loss, neurological damage and perhaps an increased rate of litigation.

Currently, high quality level I studies including Randomised Control Trials are not available for the use of Robotic Surgery in Clinical Orthopaedic Practice.

Using robotics and/or other computer-assisted devices experienced surgeons can supervise, assist or perform surgical procedures at remote locations.

The first telesurgical procedure was reported in 2001 when surgeons from New York operated on 68-year-old lady in Strasbourg, France to remove her gall bladder by remotely manipulating robotic tools.

Telesurgery has been used in several other surgical procedures such as Hernia repair and bowel resection in addition to other specialties such as urology and neurosurgery.

In orthopaedics, telesurgery is not yet well developed.

Telesurgery :

Textbook of Navigation and MIS in orthopaedic surgery – Steihl, Konermann,Haaker & Diogia – 1st Edition.

Textbook of Minimally invasive arthroplasty – Scudery 9th Annual meeting of CAOS proceedings – Davis, Kackskowicz,

Murphy. Textbook of Computer and Robotic assisted Hip and Knee Surgery –

Anthony Digio 1st edition. Manuals of Medtronic Navigation equipment ; Brain Lab; Vectoronics

; Depuy. Rockwood and Green Textbook of Orthopaedics 7 th edition. Healios – Orthopaedics Today 2007 edition – Navigation in ACL

reconstruction. Ganga Hospital : Scoliosis – Navigation course publication. JBJS journals

REFERENCES :

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