Author: Dr. Ravikumar Mukartihal

21 October, 2022

Total Knee Replacement (TKR) is widely acclaimed as the gold standard management for advanced knee osteoarthritis.

This procedure is performed in more than 600000 patients per year in the United States (US) and the number is projected to grow by 673% in 2030.

Alignment of limb and implant placement accuracy are increasingly considered among the very important prognostic factors for long-term implant survivorship, satisfaction and clinical outcome of patients.

Robotic technology in TKR is utilized to increase accuracy in implant positioning, and decrease outliers in limb alignment.

Three types of robotic system exist depending upon degree of control over the robot: autonomous (active), hands-on (semi-active) and passive. The passive systems do not perform independently the operation. They are called computer-assisted or navigation systems depending on patient- and instrument- centered reference points to provide surgeon with perioperative recommendations and guide positioning of the surgical tool.

Active robots hold cutting tool and autonomously make bone resections. Semi-active robots combine both principles with the surgeon maintaining overall control over bony resections under robot surveillance that gives a live intraoperative feedback to confine diversion from the preoperative surgical plan.

The first TKR robotic systems were active robots based on CT images: ROBODOC® (Think Surgical, Fremont, CA, USA, originally by Integrated Surgical Systems) in 1992, and CASPAR System® (U.R.S.-ortho GmbH & Co. KG, Rastatt, DE). The surgeon used to perform the surgical approach and exposition of distal femur and proximal tibia, secure limb to a fixed device and let the robot perform planned bone resections. The CASPAR system was somewhat restrictive: femoral and tibial bone screws had to be placed preoperatively (during an initial first surgery) as standard registration markers of CT-scan to allow for intraoperative robotic functions. Autonomous robots went out of choice due to fear of nerve and soft tissue injury and have been progressively superceded by semiautonomous systems.

A 3-D knee model is obtained either intra-operatively or from dedicated preoperative images via integrated surgical planning system which enables planning of bone resections and implant positioning.

The incidence of pin-related fracture as technique-related complication is quite low and overall not reported in the literature.

What is the Current evidence?

Soft tissue injury: Improved preservation of the periarticular soft tissue in robotic TKA may reduce local postoperative inflammatory response, pain and postoperative soft tissue swelling. Current literature supports that increased soft tissue protection is associated with reduced postoperative pain and periarticular swelling, leading to better early clinical outcomes.

Operating time: No significant difference exists regarding operating time between the two techniques which indicates that longer time is not associated with increased complication.

Clinical outcomes: There is increased patient satisfaction was seen in RA-TKA group with better early clinical outcomes and no significant differences of ROM were reported between the two groups. Causes of insufficient knee ROM including inappropriate component sizing, a tight extension or flexion gap, component malalignment or malrotation, dearth of rehabilitation and swelling of periarticular soft tissue seen in Conventional surgery are avoided. WOMAC and KSS scoring systems showed significantly higher scores in the RA-TKA group.

Radiological outcomes: Lower incidence of outliers was assessed for mechanical axis, coronal and sagittal femoral inclinations and coronal and sagittal tibial inclinations confirming the higher accuracy and precision of the technique. The significant higher accuracy and precision in alignment correction and the lower incidence of outliers in both coronal and sagittal planes might represent a strong determinant for implants long-term survivorship.

Learning curve: According to most studies, 12 number of RA-TKAs was required to obtain greater accuracy and precision compared with the conventional manual technique.

Cost: According to the current literature, increased costs may be partially offset since RA patients had statistically significantly lower 90-day Episode-of-Care costs, lower facility costs, shorter length-of-stay, and higher chance of being dismissed at home. One potential cost related concern is the preoperative imaging such as CT-scans; however, this enhanced imaging modality did not contribute to net higher overall healthcare costs. In robotic-assisted technique, tibial subluxation and patellar eversion are not required in order to achieve an optimal visualization, thus reducing length of hsopitalizartion.

RA-TKA in Unicompartmental Total Knee Arthroplasty: Promising results of the robotic-assisted technique have been reported in the unicompartmental total knee arthroplasty using the Robotic Arm Interactive Orthopedic (RIO) System (MAKO Surgical Corp., Ft. Lauderdale, FL, USA) with 2-to 3 year survivorship of 98.8%. Significant improved outcomes have been reported with regards to a better overall alignment and lesser complications directly related to the robotic technique.

Why Choose Robotic Total Knee Arthroplasty?

The advantages of Robotic Total Knee Arthroplasty include:

1. Precision

The surgery is completed with the help of robotics which means there is more accuracy in the area of the knee which needs the surgery. The surgery is precise and restricted as exact incisions and angles can be targeted. This helps in securing the adjacent tissues which need no repair. The functioning of the robot is such that it decreases the chance of putting the patient at risk. But one should be clear that it is a robot-controlled and not robot-centered technique.

2. Minimal Trauma:

Because robotic knee replacement is minimally invasive, there are smaller incisions and less trauma to surrounding tissues, blood vessels, nerves, muscles, and ligaments.

3. Higher Safety:

The robotic arm is programmed to remain within certain parameters based on your individual knee. This helps protect soft tissues from unintentional injury.

4. Increased Consistency and pristine accuracy

It takes the help of a computer program to ensure consistent and accurate results. It leaves no chance of any error. Such programs specifically work to deliver the best result of the surgery.

5. Faster recovery and shorter rehabilitation

Many times robotic knee replacement can be performed in an outpatient setting. A shorter hospital stay, smaller incisions, and greater accuracy all lead to faster recovery times.

6. Flexibility

Another one of the knee replacement surgery benefits is flexibility. It offers multiple implant options and dynamic ligament balancing at multiple stages.

7. Confidence

There is virtual confirmation of cuts pre and post bone removal in achieving long leg alignment and joint balance for normal knee kinematics.

8. Surgeon Controlled yet not Surgeon Dependent

The robotic replacement surgery is surgeon-controlled yet not surgeon-dependent. So it is safer and more scalable.

9. Advanced Instrumentation

The surgery proceeds with the use of advanced instruments. It is designed to enforce bone resurfacing within the surgeon defined plan. Instruments and the surgeon’s plan go hand in hand. Another thing to be kept in mind is that the surgery is not totally dependent upon the instruments. They play a crucial role in the successful completion of the surgery.

10. Longer life

Robotic knee replacement decreases implant loosening and failure. Typically, patients say that the implant feels more natural which leads to better support from the ligaments and muscles. As a result of greater outcomes, there is an increase in life expectancy for the implant itself.

11. Clinically Proven

This surgery produces clinically proven results which have been tested and verified before bringing it into operation. Robotic-assisted technique has been associated with better early functional outcomes and reduced limb malalignment compared with conventional manual-jig technique.

However, further high-quality long-term studies and RCTs comparing modern robotic systems and conventional manual technique are needed to validate the relationship between improved accuracy and implant survivorship, complication rates, functional outcomes and cost-effectiveness.

This blog is written by Dr. Ravikumar Mukartihal, Consultant Orthopaedic and Robotic Joint Replacement Surgery

Category: Orthopedics