How Does Robotic-Arm Assisted Technology Influence Total Knee Arthroplasty Implant Placement for Surgeons in Fellowship Training?

Implant malalignment during total knee arthroplasty (TKA) may lead to suboptimal postoperative outcomes. Accuracy studies are typically performed with experienced surgeons; however, it is important to study less experienced surgeons when considering teaching hospitals where younger surgeons operate. Therefore, this study assessed whether robotic-arm assisted TKA (RATKA) allowed for more accurate and precise implant position to plan when compared with manual techniques when the surgery is performed by in-training orthopaedic surgical fellows. Two surgeons, currently in their fellowship training and having minimal RATKA experience, performed a total of six manual TKA (MTKA) and six RATKAs on paired cadaver knees. Computed tomography scans were obtained for each knee pre- and postoperatively. These scans were analyzed using a custom autosegmentation and autoregistration process to compare postoperative implant position with the preoperative planned position. Mean system errors and standard deviations were compared between RATKA and MTKA for the femoral component for sagittal, coronal, and axial planes and for the tibial component in the sagittal and coronal planes. A 2-Variance testing was performed using an α = 0.05. Although not statistically significant, RATKA was found to have greater accuracy and precision to plan than MTKA for: femoral axial plane (1.1° ± 1.1° vs. 1.6° ± 1.3°), coronal plane (0.9° ± 0.7° vs. 2.2° ± 1.0°), femoral sagittal plane (1.5° ± 1.3° vs. 3.1° ± 2.1°), tibial coronal plane (0.9° ± 0.5° vs. 1.9° ± 1.3°), and tibial sagittal plane (1.7° ± 2.6° vs. 4.7° ± 4.1°). There were no statistical differences between surgical groups or between the two surgeons performing the cases. With limited RATKA experience, fellows showed increased accuracy and precision to plan for femoral and tibial implant positions. Furthermore, these results were comparable to what has been reported for an experienced surgeon performing RATKA.

Robotic-Arm Assisted Total Knee Arthroplasty Demonstrated Soft Tissue Protection.

INTRODUCTION: While total knee arthroplasty (TKA) procedures have demonstrated clinical success, occasionally intraoperative complications can occur. Collateral or posterior cruciate ligament injury, instability, extensor mechanism disruption, and tibiofemoral or patellofemoral dislocation are among a few of the intraoperatively driven adverse events prevalently ranked by The Knee Society. Robotic-arm assisted TKA (RATKA) provides a surgeon the ability to three-dimensionally plan a TKA and use intraoperative visual, auditory, and tactile feedback to ensure that only the desired bone cuts are made. The potential benefits of soft tissue protection in these surgeries need to be further evaluated. The purpose of this cadaver study was to assess the a) integrity of various knee soft tissue structures (medial collateral ligament [MCL], lateral collateral ligament [LCL], posterior cruciate ligament [PCL], and the patellar ligament), as well as b) the need for tibial subluxation and patellar eversion during RATKA procedures. MATERIALS AND METHODS: Six cadaver knees were prepared using RATKA by a surgeon with no prior clinical robotic experience. These were compared to seven manually performed cases as a control. The mean Kellgren-Lawrence score was 2.8 (range, 0 to 4) in RATKA and 2.6 (range, 1 to 4) in the manual cohort. The presence of soft tissue damage was assessed by having an experienced surgeon perform a visual evaluation and palpation of the PCL, MCL, LCL, and the patellar ligament after the procedures. In addition, leg pose and retraction were documented during all bone resections. The amount of tibial subluxation and patellar eversion was recorded for each case. RESULTS: For all RATKA-assisted cases, there was no visible evidence of disruption of any of the ligaments. All RATKA cases were left with a bone island on the tibial plateau, which protected the PCL. Tibial subluxation and patella eversion were not required for visualization in any RATKA cases. In two of the seven MTKA cases, there was slight disruption noted of the PCL, although this did not lead to any apparent change in the functional integrity of the ligament. All MTKA cases required tibial subluxation and patellar revision to achieve optimal visualization. DISCUSSION: Several aspects of soft tissue protection were noted during the study. During bone resections, the tibia in RATKA procedures did not require subluxation, which may reduce ligament stretching or decrease complication rates. Potential patient benefits for short-term recovery and decreased morbidity to reduce operative complications should be studied in a clinical setting. Since RATKA uses a stereotactic boundary to constrain the sawblade, which is generated based on the implant size, shape, and plan, and does not have the ability to track the patient's soft tissue structures, standard retraction techniques during cutting are recommended. Therefore, the retractor placement and potential for soft tissue protection needs to be further investigated. RATKA has the potential to increase soft tissue protection when compared to manual TKA.

A pre-operative approach of range of motion simulation and verification for femoroacetabular impingement.

BACKGROUND: Femoroacetabular impingement (FAI) is increasingly recognized as a potential cause of hip osteoarthritis. A system capable of pre-operatively simulating hip range of motion (ROM) by given surface models from either healthy or FAI diseased bone is desirable. METHODS: An impingement detection system using bounding sphere hierarchies was first developed. Both precision and accuracy of the impingement detection system were verified by a custom-designed phantom to imitate ball-and-socket hip movement. The impingement detection system was then implemented into the hip ROM simulation system to simulate the ROM of (1) healthy pelvis and femur, and (2) healthy pelvis and pathologic femur. The ROM simulation system was also verified by manipulating sawbones under the navigation of an optical tracking system. RESULTS: The impingement detection system achieved a distance error of 0.53 ± 0.06 mm and an angular error of 0.28 ± 0.03°. The impingement detection accuracies were 100%, 100%, and 96% in three different phantom orientations, respectively. The mean errors between simulated and verified ROM were 0.10 ± 1.39° for the 'healthy pelvis and femur' group, and - 2.38 ± 3.49° for the 'healthy pelvis and pathologic femur' group. CONCLUSION: The present study demonstrates a pre-operative approach to virtually simulate and predict the functional hip ROM based on the given bone models. The impingement detection and ROM simulation systems developed may also be used for other orthopedic applications.

Three-dimensional A-mode ultrasound calibration and registration for robotic orthopaedic knee surgery.

BACKGROUND: Registration is a key step for computer-navigated robot-assisted surgery. Registration links the live patient anatomical location to the prescanned CT or MRI images, so that predesigned procedures can be performed accurately. Fiducial markers or mechanical probes are usually used to identify anatomical features or collect data points for registration. This conventional invasive approach is common; however, using ultrasound probes may provide a non-invasive alternative. METHODS: This report presents investigations of selecting an A-mode ultrasound transducer, calibrating it, analysing the ultrasound signal and using it to register phantom-sawbones of tibia and femur as well as cadaveric specimens. To ensure accurate registration, the A-mode ultrasound probe is calibrated by a designed calibration system. Detailed mathematical derivation and procedures for the calibration are provided in the Appendix. The calibration and registration experiments were performed in conjunction with MAKO Surgical Corporation's Tactile Guidance System (TGS) at their headquarters and at the South Florida Spine Clinic for cadaveric experiments. RESULTS: Calibration results show that an A-mode ultrasound probe can reach the same accuracy level as a mechanical probe. By using the A-mode ultrasound probe, averaged root mean square errors (RMSE) are <0.5 mm for calibration, <1.0 mm for phantom-sawbones and <2.0 mm for cadaveric specimens. CONCLUSION: The registration results from phantom and cadaveric experiments are suitable for clinical applications. A-mode ultrasound registration is a viable option for registration of the bones in orthopaedic knee surgery but with reduced incision size.