A novel technique using sensor-based technology to evaluate tibial tray rotation

Variability between the trial and final implant measurements during the sensor-guided total knee arthroplasty

PURPOSE

Compartmental load-sensing technology has been used in the attempt to achieve optimal soft tissue balance during total knee arthroplasty (TKA). This study was conducted to investigate the validity of such use of intraoperative sensing technology.

METHODS

Ninety-three knees scheduled to undergo total knee arthroplasty for knee osteoarthritis with a tibial sensor were prospectively enrolled. Measurements were divided into three groups according to the three different time points of intraoperative load testing: group Trial (with the trial components), group Final (with the definitive cemented implants and an open joint capsule), and group Closed (with the definitive cemented implants and a closed joint capsule). Load measurements and component rotational alignments were documented at 10°, 30°, 45°, 90°, and 120° of flexion for all three groups, and compared. One year postoperatively, the joint line obliquity angle was obtained radiographically in the valgus and varus stress views at 10° and 30° flexion to evaluate the clinical instability. The Knee Society, Hospital for Special Surgery, and Western Ontario McMaster Universities Osteoarthritis Index scores were used to determine functional outcomes. The correlations of the above outcomes with intraoperative load were evaluated.

RESULTS

There were significant differences in medial and lateral loads at all flexion angles (except at a 120° lateral load) between group Trial and group Final (p < 0.05). Tibial trays were internally rotated to a significantly higher degree in group Final than in group Trial (p = 0.010). The lateral compartmental load significantly decreased after patellar inversion (p = 0.037). There were no correlations of intraoperative load with clinical instability and functional outcomes.

CONCLUSION

Significant variability was observed between the trial and final implant measurements and intraoperative sensing data were not correlated with instability or functional outcomes over a 1-year period. Therefore, intraoperative sensor technology provides limited feedback and clinical efficacy in the adjustment of the soft tissue balance during TKA.

LEVEL OF EVIDENCE

Level II.

Optimal designs and surgical technique for hip and knee joint replacement: The best is yet to come!

Over the last three decades, there have been significant advancements in knee and hip replacement technology. The implants and the surgical technology we now have to aid in their implantation are advancing and improving functional outcomes and survivorship. Despite these advancements, there are still issues with patient satisfaction, functional limitations, and early revisions due to instability and aseptic loosening. This article reviews the state of current technology in hip and knee replacement implant design and surgical technique, and reviews some of the current implant designs and surgical technologies that may be able to solve some of the most common issues in the knee and hip replacement surgery.

Soft-Tissue Balancing Technology for Total Knee Arthroplasty

» Improperly balanced total knee arthroplasties are at increased risk for complications including residual pain and/or instability, which are often corrected by a revision surgical procedure. » Because of the morbidity and financial burden associated with revision total knee arthroplasty, different technological applications, such as tibial insert sensors and computer-assisted gap balancing, are being used to assist with soft-tissue balancing during primary total knee arthroplasty. » Computer-assisted gap balancing increases the accuracy of mechanical alignment and improves the precision of balancing flexion and extension gaps during total knee arthroplasty. It is unclear whether this translates to improved short-term or long-term outcome measures. Considerations of this technology include increased cost, increased operative time, and a steep learning curve. » Intraoperative sensors increase the accuracy of balancing by quantifying the mediolateral intercompartmental load distribution through the range of motion, which may lead to improved outcome scores, patient satisfaction, higher activity levels, and decreased pain. The advantages of this technology compared with computer assistance include decreased cost and no disruption of operative time or workflow. Limited availability with constrained implants, limited implant choices, and a lack of long-term follow-up data have reduced utilization of intraoperative sensors. » Computer-assisted gap balancing and intraoperative sensors are not yet universally accepted, and the cost-benefit ratio associated with their use remains a consideration in today’s cost-conscious health-care environment. Future research should focus on longer-term follow-up to evaluate implant survivorship, cost-effectiveness, and clinical outcomes.

Advances in Computer-Aided Technology for Total Knee Arthroplasty

Technology such as computer-assisted navigation systems, robotic-assisted systems, and patient-specific instrumentation has been increasingly explored during the past decade in an effort to optimize component alignment and improve clinical outcomes. Computer-assisted navigation accurately restores mechanical-axis alignment, but clinical outcome data are inconsistent. Computer-assisted navigation gap balancing has shown early promise in establishing mechanical-axis alignment with improved functional outcomes. Robotic-assisted systems more accurately restore component alignment when compared with computer-assisted navigation, but clinical outcomes have yet to be determined. Patient-specific instrumentation does not consistently improve alignment, accuracy, or patient outcomes. Studies demonstrating implant survivorship, cost-efficiency, and improved clinical outcomes and patient satisfaction are needed. [Orthopedics. 2017; 40(6):338-352.].

Can We Really "Feel" a Balanced Total Knee Arthroplasty?

BACKGROUND

Balancing techniques in total knee arthroplasty are often based on surgeons' subjective judgment. However, newer technologies have allowed for objective measurements of soft tissue balancing. This study compared the use of sensor technology to the 30-year surgeon experience regarding (1) compartment loads, (2) soft tissue releases, and (3) component rotational alignments.

METHODS

Patients received either sensor-guided soft tissue balancing (n = 10) or manual gap balancing (n = 12). Wireless, intraoperative sensor tibial inserts were used to measure intracompartmental loads. The surgeon was blinded to values in the manual gap-balancing cohort. In the sensor cohort, the surgeon was unblinded, and implant trials were placed after normal releases were performed to guide further ligament releases after femoral and tibial resections, as needed. Load measurements were taken at 10°, 45°, and 90°.

RESULTS

The sensor cohort had lower medial and lateral compartment loading at 10°, 45°, and 90°. The sensor group had lower mean differences in intercompartment loading at 10° (-5.6 vs -51.7 lbs), 45° (-9.8 vs -45.9 lbs), and 90° (-4.3 vs -27 lbs) compared to manually balanced patients. There were 10 additional soft tissue releases in the sensor cohort (2 initial ones before sensor use), compared to 2 releases in the gap-balanced cohort. In the gap-balanced cohort, tibial trays were positioned at a mean 9° external rotation, compared to a mean 1° internal rotation in the sensor-guided cohort.

CONCLUSION

Sensor-balanced total knee arthroplasties provide objective feedback to perform releases and potentially improve knee balancing and rotational alignment. Future work may clarify whether these changes are beneficial for our patients.

A Systematic Literature Review of Three Modalities in Technologically Assisted TKA

In effort to reduce the revision burden of total knee arthroplasty (TKA), industry emphasis has focused on replacing manual techniques—which are subject to variability—with technological implements. Unfortunately, technological innovation often continues before adequate time for critical evaluation has passed. Therefore, the purpose of this descriptive literature review was to collect a large sample of international data and report on the clinical and economic efficacy of three major types of technologically assisted TKA: navigation, patient-specific instrumentation, and sensorized trials.