Dr Sanjeev Jain performs all his joint replacement surgeries using latest state of the art navigation system for knee replacement and hip resurfacing. Computer-aided methods in joint replacement improve the precision and accuracy of implant positioning and ligament balancing, producing better clinical results that improve the life of the implants.
Principle of CAS
The principle of CAS is straightforward. A similarity can be drawn between CAS to assist in surgery and GPS to assist with navigating and route planning. Both provide a means for getting to the next stage, ie. In providing accurate positional information that allows better decision-making
CAS is incorporated with software to process images real time. A digital model is produced that serves as a map for each particular procedure. The image is then made available to surgeons to guide them through the operation.
Surgical instruments can be incorporated into the map so that instrument position, attitude, and progress can be monitored and controlled to within fractions of millimeters. Surgeons can use this real-time data to correct the procedure intra-operatively. This is much different from non-CAS surgery as the prosthetic evaluation by X-ray is done post-operatively. Should there is any incorrect prosthetic alignment; there is a greater likelihood of requiring a subsequent revision. There is a greater risk for post-operative complication as well as increased costs. In this case of incorrect prosthetic alignment from non-CAS surgery, the patient and physician must accept the surgical outcome, including the likelihood of shortened total knee arthroplasty life span.
How CAS Works
A sensing device is attached to the patient’s for patient data registry and an infrared camera will help receive the data for processing and create each patient’s digital model. The software contains data for various types and sizes of prostheses. The computer will then assist the surgeon with enough information to prepare the best bone bed surface for each particular type of prosthesis, as well as assisting the surgeon in choosing the optimal prosthetic size for the patient.
The surgeon will then apply the data from the CAS system to shape a fitted bone bed. CAS also helps in monitoring the accuracy of the bone bed shape preparation. If there is a mal-alignment, timely correction can be performed right away. The latest version of the software enables the surgeon to determine the balance of the surrounding ligament and muscle. The ultimate goal is for optimum functionality and durability over time.
Advantages of Computer Assisted Surgery
- Cutting bone and positioning the components with an accuracy up to 0.5 degrees and 0.5 mm
- Constant guidance, monitoring and confirmation during surgery -ability to judge the bony cuts before actually making the cuts
- Ability to verify the cut to very precise accuracy
- Increased implant longevity.
- 3 Dimensional planning.
- No radiation during surgery.
- Range of motion analysis to achieve maximum function.
- Correct implant selection and placement.
- Decreased incidence of pulmonary embolism in knee surgery.
- Minimally invasive surgery, hence
a) Decreased blood loss.
b) Decreased hospital stay.
- Reduced complications like
c) Limb length inequality
CAS and MIS (Minimally Invasive Surgery)
Presently, a new procedure of Minimally Invasive Surgery (MIS) is widely recognized as it produces minimal incision and enhances cosmetic results. That is why CAS must be incorporated with MIS if adequate results are expected. When CAS is applied with MIS, the surgeon can see through the incision using a CAS monitor, enhancing visualization and surgical accuracy. The likelihood of prosthesis mal-alignment will then be reduced. It is believed that CAS in conjunction with MIS is a promising area in orthopedic surgery.