Total knee arthroplasty with a computer-navigated saw: a pilot study

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.

Assessment of Limb Alignment and Component Placement After All Burr Robotic-Assisted TKA

BACKGROUND

All burr robotic-assisted total knee arthroplasty (R-TKA) is the new way of doing TKA without conventional jigs and saw. The aim of this study is to assess the accuracy of limb alignment and component placement after R-TKA.

METHODS AND MATERIALS

This is the prospective study of 63 patients who underwent R-TKA between March and October 2019. Standing scanogram and AP/lateral radiograph were done on day of discharge, 5th day after surgery to calculate limb alignment and component placement angles in coronal and sagittal plane. Deformity correction Bone Ninja software had been used to calculate all this angles.

RESULTS

Mean difference between robotic achieved and postoperative limb alignment was 1.24°. Mean difference between planned and achieved component placement in coronal and sagittal plane for tibia was 0.33° and 0.66° and for femur was 0.62° and 0.30°, respectively. Posterior condylar offset difference was 0.03. As per planned by Navio software, R-TKA had reduced the overall outlier of coronal limb alignment from 3° to less than 1.2° and component placement malposition to less than 1° in coronal and sagittal plane.

CONCLUSION

R-TKA provides near perfect limb alignment and near accurate femoral/tibial component placement as planned in both coronal and sagittal plane. Posterior condylar offset was also perfectly maintained. R-TKA had reduced the overall outlier of coronal limb alignment from 3° to less than 1.2° and component placement malposition to less than 1° in coronal and sagittal plane.

Kellgren-Lawrence grade of osteoarthritis is associated with change in certain morphological parameters

BACKGROUND

To compare selected morphological parameters between normal and osteoarthritic (OA) knees, as well as to evaluate differences in these parameters between Kellgren-Lawrence (K-L) grades of OA.

METHODS

Knee joint morphology was evaluated using magnetic resonance (MR) images of 200 participants with knee OA (50 each of K-L grades 1-4) and 50 without knee OA, matched for age, body mass index, sex, and tibiofemoral angle. Knees with a coronal alignment within five degrees of neutral and no apparent bone loss on radiographs were included. Twenty-one morphologic parameters of the distal femur and proximal tibia were measured on MR images. Correlation between the K-L grade and measured parameters and differences in measured parameters across the K-L grades and between the OA and control groups were evaluated.

RESULTS

The K-L grade was significantly correlated with multiple distal femur measurements including the posterior condylar angle (PCA), lateral epicondyle to posterior condylar cartilage (LEPC) length, medial epicondyle to posterior condylar cartilage (MEPC) length, medial epicondyle to distal cartilage (MEDC) length, medial tibial slope angle, femoral condylar cartilage height difference (FCHDc), and femoral condylar bone height difference (FCHDb) (P < 0.05). A significant difference was identified between the different K-L grades with regard to PCA, LEPC, MEPC, MEDC, and FCHDc (P < 0.05). There was no correlation between K-L grade and measured proximal tibial parameters.

CONCLUSIONS

Among knees without significant angular deformity, progression of knee OA is associated with a change in the morphology of the femoral condyles but not of the proximal tibia.

Accuracy assessment of a novel image-free handheld robot for Total Knee Arthroplasty in a cadaveric study

Surgical navigation has been shown to improve the accuracy of bone preparation and limb alignment in total knee arthroplasty (TKA). Previous work has shown the effectiveness of various types of navigation systems. Here, for the first time, we assessed the accuracy of a novel imageless semiautonomous handheld robotic sculpting system in performing bone resection and preparation in TKA using cadaveric specimens. In this study, we compared the planned and final implant placement in 18 cadaveric specimens undergoing TKA using the new tool. Eight surgeons carried out the procedures using three types of implant designs. A quantitative analysis was performed to determine the translational, angular, and rotational differences between the planned and achieved positions of the implants. The mean femoral flexion, varus/valgus, and rotational error was -2.0°, -0.1°, and -0.5°, respectively. The mean tibial posterior slope, and varus/valgus error was -0.2°, and -0.2°, respectively. We obtained higher flexion errors for the femoral implant when using cut-guides as compared to using a bur for cutting the bones. The image-free robotic sculpting tool achieved accurate implementation of the surgical plan with small errors in implant placement. Future studies will focus on determining how well the accurate implant placement translates into a clinical and functional benefit for the patient.

Robotic Total Knee Arthroplasty: Surgical Assistant for a Customized Normal Kinematic Knee

Although current total knee arthroplasty (TKA) is considered a highly successful surgical procedure, patients undergoing TKA can still experience substantial functional impairment and increased revision rates as compared with those undergoing total hip arthroplasty. Robotic-assisted surgery has been available clinically for almost 15 years and was developed, in part, to address these concerns. Robotic-assisted surgery aims to improve TKA by enhancing the surgeon's ability to optimize soft tissue balancing, reproduce alignment, and restore normal knee kinematics. Current systems include a robotic arm with a variety of different navigation systems with active, semi-active, or passive control. Semi-active systems have become the dominant strategy, providing a haptic window through which the surgeon consistently prepares a TKA based on preoperative planning. A review of previous designs and clinical studies demonstrates that these robotic systems decrease variability and increase precision, primarily with the mechanical axis and restoration of the joint line. Future design objectives include precise planning and consistent intraoperative execution. Preoperative planning, intraoperative sensors, augmenting surgical instrumentation, and biomimetic surfaces will be used to re-create the 4-bar linkage system in the knee. Implants will be placed so that the knee functions with a medial pivot, lateral rollback, screw home mechanism, and patellar femoral tracking. Soft tissue balancing will become more than equalizing the flexion and extension gaps and will match the kinematics to a normal knee. Together, coupled with advanced knee designs, they may be the key to a patient stating, "My knee feels like my natural knee." [Orthopedics. 2016; 39(5):e822-e827.].

Alignment in knee flexion position during navigation-assisted total knee arthroplasty

PURPOSE

The aim of this study was to demonstrate the lower limb alignment in knee flexion position after navigation-assisted total knee arthroplasty using the gap technique and to identify the correlative factors.

METHODS

One hundred and twenty consecutive osteoarthritic knees (120 patients) were prospectively enrolled for intraoperative data collection. All TKA surgeries were performed using the navigation system (OrthoPilot™, version 4.0; B. Braun Aesculap, Tuttlingen, Germany). Before and after final prosthesis implantation, the lower limb navigation alignment in both knee extension (0°) and knee flexion (90°) position was recorded. The knee flexion alignment was divided into three groups: varus, neutral and valgus alignment. To determine the factors of the alignment in knee flexion position, preoperative demographics, radiologic and intraoperative data were obtained. Pearson's correlation (r) analysis was performed to find the correlation. The Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index were compared between groups.

RESULTS

Although all postoperative extension alignment was within neutral position (between -2° and +2°), postoperative knee flexion alignment was divided into three groups: varus (≤-3°), 24 cases (20 %); neutral (between -2° and +2°), 85 cases (70.8 %) and valgus (≥+3°) alignment, 11 cases (9.2 %). There were a good correlation of alignment in knee flexion position with the rotation of femoral component relative to posterior condylar axis (r = -0.502, p = 0.000) and weak correlations with posterior femoral cut thickness (lateral condyle) (r = 0.207, p = 0.026), medial flexion (90°) gap after femoral component rotation adjustment (r = 0.276, p = 0.003). Other variables did not show correlations. There were no statistical clinical differences between varus, neutral and valgus knee flexion alignment groups.

CONCLUSION

About 30 % of the cases showed malalignment of more than 3° in knee flexion position although with neutral alignment in extension position. The knee flexion alignment had a good correlation with the rotation of femoral component relative to posterior condylar axis. Neutral alignment in knee flexion position may be adjusted by femoral component rotation especially by the use of navigation system.

LEVEL OF EVIDENCE

IV.

Alignment of the lower extremity mechanical axis by computer-aided design and application in total knee arthroplasty

PURPOSE

The success of total knee arthroplasty (TKA) depends on many factors. The position of a prosthesis is vitally important. The purpose of the present study was to evaluate the value of a computer-aided establishing lower extremity mechanical axis in TKA using digital technology.

METHODS

A total of 36 cases of patients with TKA were randomly divided into the computer-aided design of navigation template group (NT) and conventional intramedullary positioning group (CIP). Three-dimensional (3D) CT scanning images of the hip, knee, and ankle were obtained in NT group. X-ray images and CT scans were transferred into the 3D reconstruction software. A 3D bone model of the hip, knee, ankle, as well as the modified loading, was reconstructed and saved in a stereolithographic format. In the 3D reconstruction model, the mechanical axis of the lower limb was determined, and the navigational templates produced an accurate model using a rapid prototyping technique. The THA in CIP group was performed according to a routine operation. CT scans were performed postoperatively to evaluate the accuracy of the two TKA methods.

RESULTS

The averaged operative time of the NT group procedures was [Formula: see text] min shorter than those of the conventional procedures ([Formula: see text]  min). The coronal femoral angle, coronal tibial angle, posterior tibial slope were [Formula: see text], [Formula: see text], [Formula: see text] in NT group and [Formula: see text], [Formula: see text], [Formula: see text] in CIP group, respectively. Statistically significant group differences were found.

CONCLUSIONS

The navigation template produced through mechanical axis of lower extremity may provide a relative accurate and simple method for TKA.

Alignment of the tibial component in total knee arthroplasty procedures using an intramedullary or extramedullary guide: double-blind randomized prospective study

Objectives

To evaluate the results obtained through using an intramedullary or extramedullary guide for sectioning the tibia in total knee arthroplasty procedures, with a view to identifying the accuracy of these guides and whether one might be superior to the other.

Methods

This was a randomized double-blind prospective study on 41 total knee arthroplasty procedures performed between August 2011 and March 2012. The angle between the base of the tibial component and the mechanical axis of the tibia was measured during the immediate postoperative period by means of radiography in anteroposterior view on the tibia that encompassed the knee and ankle.

Results

There was no demographic difference between the two groups evaluated. The mean alignment of the tibial component in the patients of group A (intramedullary) was 90.3° (range: 84–97°). In group B (extramedullary), it was 88.5° (range: 83–94°).

Conclusion

In our study, we did not find any difference regarding the precision or accuracy of either of the guides. Some patients present an absolute or relative contraindication against using one or other of the guides. However, for the other cases, neither of the guides was superior to the other one.