Development of a 9 Axes Machine Tool for Bone Cutting

BackgroundThe primary objective of this study was to determine the accuracy and precision of component positioning of the ROSA Robotic System for total knee arthroplasty (TKA). MethodsA Preferred Reporting Items for Systematic Reviews and Meta-Analysis systematic review was conducted using 4 electronic databases (MEDLINE, EMBASE, Pubmed, and Cochrane Library) to identify all clinical and radiological studies reporting information about the use and results of the ROSA system. The criteria for inclusion were published research articles evaluating the accuracy of component positioning, learning curve, component alignment, complications, and functional outcomes in adults who underwent robotic-assisted TKA. The National Institutes of Health Quality Assessment Tool was used to evaluate the quality of all the included studies. ResultsA total of 26 studies were assessed for eligibility, and 17 met the inclusion criteria. Nine studies reported on the accuracy and precision of component positioning. The ROSA platform for TKA had a cutting error of less than 0.6° for all coronal and sagittal parameters. Pooled analysis demonstrated accuracy within 0.61-1.87° and precision within 0.97-1.34° when the final intraoperative plan was compared to postoperative radiographs with fewer outliers. Four studies reported improved functional scores with ROSA-assisted TKA than conventional TKA within 1 year of surgery. There was no difference in overall complication rates when compared to conventional TKA. ConclusionsThe ROSA system is both highly accurate and precise, with fewer outliers when analyzed at various time points, including postoperative standing radiographs. Future studies with robust methodology and longer follow-up are required to demonstrate whether these findings have any clinical benefits in the long term.

PurposeThe aim of this study is to assess the accuracy of alignment determined by patient-specific instrumentation system in total knee arthroplasty (TKA).Materials and MethodsTwenty-seven TKAs using patient-specific instrument were reviewed. The intraoperative pin location determined by the patient-specific guide was recorded using imageless navigation software. Data recorded included tibial coronal alignment and posterior slope, femoral coronal alignment and sagittal alignment, and transepicondylar axis. A discrepancy within ±3° in each plane was considered an acceptable result.ResultsOn the tibia, an acceptable alignment was obtained in 24 (88.1%) in the coronal plane and 21 (77.8%) in the sagittal plane. On the femur, a satisfactory alignment was obtained in 25 (92.6%) in the coronal plane and 24 (88.1%) in the sagittal plane. Based on the transepicondylar axis, a satisfactory alignment was obtained in 23 (85.1%).ConclusionsSatisfactory alignment was obtained in more than 85% of each plane of the femur and in the coronal plane of the tibia and relative to the transepicondylar axis. Sufficeint experience and precise preoperative planning are required to improve the accuracy of sagittal alignment of the tibia.

Technological advances alongside increased demand for knee replacement surgery have led to the development of a novel image-free bed rail-mounted robotic-assisted system for total knee arthroplasty (TKA). The device is capable of real-time tracking to accommodate for leg motion during bone resection allowing for precise control and positioning of the bone saw in the planned resection plane. The purpose of this study is to discuss the versatility and accuracy of this novel image-free robotic-assisted technology in TKA. The novel robotic-assisted system underwent a stepwise assessment to verify its versatility and accuracy. First, functional accuracy was bench tested to evaluate predetermined surgical plans independent of user variability and anatomic variability compared to conventional instrumentation. This was followed by assessments utilizing cadaveric specimens for resection accuracy, implant positioning, and soft tissue involvement. Test bench accuracy revealed overall pooled linear positional accuracy of 0.326 ± 0.249mm and pooled angular positional accuracy of 0.365 ± 0.611°. Resection errors for both robotic and conventional cohorts ranged between 0.6° and 1.9°. Concerning coronal alignment, 33/40 robotic specimen were within ± 1° and 38/40 within ± 3° of the femoral varus-valgus target, compared with 17/40 and 37/40 with conventional instrumentation, respectively. Twenty-four of the 40 robotic specimens were within ± 1° and 40/40 within ± 3° of the tibial varus-valgus target compared with 15/40 and 32/40 with conventional instrumentation, respectively. Soft tissue structures were uncompromised in all robotic-assisted cases. Conventional instruments revealed two cases of partial cleavage of the posterior cruciate ligament and two instances of a compromised posterior medial capsule. There were no significant differences between the two techniques concerning the samples that were uncompromised and fully functional (40/40 vs. 38/40, p = 0.49). The novel image-free robotic-assisted surgical system demonstrates excellent benchtop accuracy to aid bony resection in cadaveric specimens. It offers notable improvement in coronal implant alignment compared to conventional instrumentation.

Intraoperative kinematic analysis using a navigation system in total knee arthroplasty (TKA) has been increasing. The purpose of the present study was to assess the reproducibility of the intraoperative kinematics analysis in TKA using the image-free knee navigation system. Fifty-one knees in 45 patients who received TKA, performed by a single surgeon (the senior consultant) with the resident, were included in this retrospective study. There were 7 men and 38 women and the mean age was 74.3 years. Cruciate retaining (CR) type and posterior stabilized (PS) type implants were inserted into 38 and 13 knees. The senior consultant and the resident analyzed initial kinematics, the axial rotation of the tibia and the coronal alignment of the lower limb, three times in each knee on manual passive knee flexion intraoperatively using the navigation system. Intra-class correlation coefficients (ICC) with 95 % confidence intervals were calculated to determine the reproducibility of this analysis. In regard to intra-rater reproducibility with axial rotation of the tibia, the ICC of the senior consultant was 0.965 for CR knees and 0.972 for PS knees while the ICC of the resident were 0.966 and 0.956. Inter-rater reproducibility was excellent for both knee types (ICC, 0.885 for CR knees and 0.864 for PS knees). In regard to intra-rater reproducibility with coronal alignment of the lower limb, ICC of the senior consultant was 0.990 for CR knees and 0.996 for PS knees while those of the resident were 0.990 and 0.995. Inter-rater reproducibility was also excellent for both knee types (ICC, 0.978 for CR knees and 0.994 for PS knees). Manual intraoperative kinematic analysis using a navigation system in TKA showed excellent reproducibility. This result may encourage further studies about intraoperative kinematic analysis using a navigation system in TKA.

Successful total knee arthroplasty is dependent on the correct alignment of implanted prostheses. Major clinical problems can be related to poor femoral component positioning, including sagittal plane and rotational malalignment. A prospective randomized study was designed to test whether an optical navigation system for total knee arthroplasty achieved greater implantation precision than a nonnavigated technique. The primary variable was rotation of the femoral component in the transverse plane, measured from postoperative radiographs and computed tomography images. Sixty-four patients were included in the study. All patients received the Duracon total knee prosthesis. The patients were randomly divided into two groups: Group C patients had conventional total knee arthroplasty without navigation; Group N patients had total knee arthroplasty using a computer-assisted knee navigation system. Analysis showed that patients in Group N had significantly better rotational alignment and flexion angle of the femoral component than patients in Group C. In addition, superior postoperative alignment of the mechanical axis, posterior tibial slope, and rotational alignment was achieved for patients in Group N. The use of a navigation system provides improved alignment accuracy, and can help to avoid femoral malrotation and errors in axial alignment.

Aim This study aims to investigate the differences between the MAKO CT-based robotic-assisted system and the conventional technique for TKA, focusing on assessing patient outcomes, surgical time and costs. Background Total knee arthroplasty (TKA) is a surgical procedure that replaces a damaged knee joint. The conventional method involves surgically removing the damaged knee joint and replacing it with an implant. In contrast, the MAKO system TKA is an amalgamation of robotic surgery with a CT-based 3D model of the patient’s knee. Method A PRISMA systematic review was conducted using 4 databases (Cochrane, Google Scholar, OVID and Pubmed) to identify all studies that reported the use and results of the CT-based robotic-assisted system to perform TKA. The outcome criteria investigated included patient-reported scores, implant alignment, analgesia requirements, estimated blood loss, surgical time, operation time, tourniquet time, implant thickness variations, and length of hospital stay. Results 141 studies were identified, of which 17 met the inclusion criteria. Of those, 13 were included in this study. The MAKO CT-based robotic-assisted system, compared to conventional methods for TKA, resulted in similar patient outcomes, higher implant precision, lower analgesia requirements, lower blood loss, longer operation time, longer tourniquet time, lower implant thickness, and shorter hospital stays. Due to several factors, the cost of the MAKO CT-based robotic-assisted system for TKA could be less than that of conventional TKA. Conclusions The MAKO CT-based robotic-assisted system for TKA does not lead to different patient outcomes but should be considered in practice in light of other supporting parameters improving surgical care.

Robotically-assisted total knee arthroplasty (TKA) has been shown to improve alignment and decrease outliers, an important goal in TKA procedures. The purpose of this cadaveric study was to compare the accuracy and reproducibility of a recently introduced TKA robotic system to conventional instrumentation for bone resections. This cadaveric study compared 14 robotically-assisted TKA with 20 conventional TKAs. Four board-certified high volume arthroplasty surgeons with no prior experience in robotics (except one) performed the procedures with three different implant systems. Angle and level of bone resections obtained from optical navigation or calliper measurements were compared to the intra-operative plan to determine accuracy. Group comparison was performed using Student t test (mean) and F test (variance), with significance at p < 0.05. The robotic group demonstrated statistically more accurate results (p < 0.05) and fewer outliers (p < 0.05) than conventional instrumentation when aiming for neutral alignment. Final limb alignment (HKA) had an accuracy of 0.8° ± 0.6° vs 2.0° ± 1.6°, with 100% vs 75% of cases within 3° and 93% vs 60% within 2°. For the robotically-assisted knees, the accuracy of bone resection angles was below 0.6° with standard deviations below 0.4°, except for the femur flexion (1.3° ± 1.0°), and below 0.7mm with standard deviations below 0.7mm for bone resection levels. This in vitro study has demonstrated that this novel TKA robotic system produces more accurate and more reproducible bone resections than conventional instrumentation. It supports the clinical use of this new robotic system. Cadaveric study, Level V.

Total knee arthroplasty performed with inertial navigation within the surgical field

Malalignment causes abnormal forces that may lead to loosening after knee replacement. Whether a computer-assisted technique can improve the precision of implant positioning guaranteeing good long-term results in total knee arthroplasty, this is a matter of discussion. The authors evaluate the alignment accuracy of 20 primary total knee arthroplasties, performed using an image-free computer navigation systems, with standardized CT protocol and three-dimensional digital model reconstruction. The results of this study demonstrate that the image-free navigation system is able to improve accuracy in axial limb alignment and positioning of the components in the majority of cases; moreover, the difference between the mean mechanical axis value of the navigation system (179.7°±1.7°) and the median mean value obtained during the post-operative evaluation (180.3°±1.9°) is not statistically significant (P=0.28).

Intraoperative Tibial Anteroposterior Axis Could Not Be Replicated After Tibial Osteotomy in Total Knee Arthroplasty

IntroductionMany of the functional complications that arise after total knee arthroplasty (TKA) are caused by a non-optimal balance of the knee after surgery. Over the past 20 years, technology has been used in the Operating Room (OR) to help improve precision and balance. The results of Computer-Assisted Surgery (CAS) and robotic systems show improved accuracy regarding implant positioning but a relatively small improvement in patient-reported outcomes and implant survival compared to conventional TKA. Recently, Augmented Reality (AR) has been proposed as a technology that could improve accuracy in orthopaedic surgery, providing a more efficient and cost-effective solution.Materials and methodsThis article describes a novel AR-based surgical guidance system that measures intra-operatively the effect of prosthesis alignment and positioning on soft tissue balance. The system is integrated in a pair of smart glasses and two small sensors and displays surgical targets directly in the field of view of the surgeon.ResultsThe system has been used in a limited number of cases. While the preliminary experience has been positive, clinical research is ongoing to confirm to confirm the performance of the system and the impact on clinical outcomes.ConclusionAugmented Reality can be a valuable tool to improve accuracy in TKA. The use of smart glasses and integrated sensors improves the efficiency of the procedure, particularly when coupled with single-use instrumentation. A novel protocol for soft tissue assessment allows for a 3-dimensional evaluation of the ligaments and a better measurement of the effect of tibial rotation.

The purpose of the study was to compare the rate of secondary resurfacing in a consecutive series of five different total knee arthroplasty (TKA) systems. It was our hypothesis that different TKA design features such as sulcus angle or trochlear height influence the rate of secondary resurfacing. A retrospective study was performed on data from patients who underwent TKA without primary patellar resurfacing from 2004 to 2012 in an university-affiliated hospital. The study cohort included 784 TKA patients (m:f=302:482, mean age at surgery±SD 71±10). Five different cruciate-retaining TKA systems were used consecutively (Group A, Triathlon, Stryker, Switzerland (n=296), Group B, PFC Sigma, DepuySynthes, Switzerland (n=215), Group C, LCS, DepuySynthes, Switzerland (n=81), Group D, Balansys, Mathys, Switzerland (n=128), Group E, Duracon, Stryker, Switzerland (n=64)). Data were retrospectively obtained from hospital archives. Patients demographics, age at surgery, type of TKA were noted. In addition, TKA component position was assessed on radiographs with respect to "The knee society total knee arthroplasty roentgenographic evaluation and scoring system" (TKA-RESS). Pearson Chi-square test was used to compare differences between groups (p<0.05). There were no significant differences between the groups in terms of age, gender, and radiological outcomes. Twenty-six of 784 patients (3.3%) underwent secondary resurfacing due to patellofemoral pain. In group A 4/296 patients (1.4%), in group B 15/215 patients (7%), in group C 5/81 patients (6.2%), in group D 1/128 patients (0.8%), in group E 1/64 patients (1.6%) underwent secondary patellar resurfacing during follow-up. Significantly higher rates of secondary patellar resurfacing were seen in groups B and C when compared to the others (p<0.001). It was found that the trochlear height in these TKA was higher than in the others. Based on the findings of this study, trochlear height influences the need for secondary patellar resurfacing. The resurfacing rate ranged from 1 to 7%, with the highest rate in the PFC Sigma TKA. Therapeutic study, Level III.

A Development of Force Distribution Measurement System in Total Knee Arthroplasty and Its Fundamental Results

Mixed-reality total knee arthroplasty (MR-TKA) allows for simultaneous viewing of the surgical field and overlaid data to potentially match the accuracy of robotic-assisted TKA (RA-TKA) but with minimal footprint and open platform compatibility. This study compared the in vivo accuracy of this novel MR-TKA system to a well-established RA-TKA system. Data was collected from 40 TKA cases utilizing an FDA-cleared MR-TKA system and 40 modern imageless RA-TKA cases from June 2024 to February 2025. Deviations from intraoperative planned coronal femoral, tibial, and hip-knee-ankle alignment to actual alignment, measured on postoperative radiographs, were compared. Mean variance values between the thickness of planned and caliper-measured resections were also compared. Operative times and postoperative complications were collected. Mean angular variance in femoral (0.9 vs 0.8°, P = .525), tibial (0.8 vs 0.7°, P = .458), and hip-knee-ankle (1.1 vs 0.8°, P = .078) coronal alignment were not significant between RA-TKA and MR-TKA cohorts, respectively. Mean depth variance in distal femoral (medial 0.6 vs 0.8 mm, P = .083; lateral 0.6 vs 0.8 mm, P = .078), posterior femoral (medial 0.6 vs 0.8 mm, P = .246; lateral 0.7 vs 0.6 mm, P = .464), and tibial (medial 0.6 vs 0.7 mm, P = .482; lateral 0.7 vs 0.7 mm, P = 1.00) resections were not significant. Mean operative time was longer with MR-TKA (107 vs 95 min, P = .002). A novel MR-TKA system provides similar accuracy in both resection depths and component alignment compared to an imageless RA-TKA platform.

The Vega System® PS (Aesculap AG, Tuttlingen, Germany) is an advanced, third generation fixed implant that aims to mimic natural knee kinematics by optimizing pivotal motion while reducing surface stress. This study evaluated mid-term survival and clinical outcomes, including range of motion (ROM) of the modern posterior stabilized implant in order to analyse whether this biomechanically successful implant reaches good results in situ. The first 100 patients to receive the Vega PS System for total knee arthroplasty were invited to take part in this single centre, single surgeon study. Of these, 84 patients were clinically assessed 5-6 years postoperatively. Data which was obtained during this follow-up examination included revision data, range of motion and clinical scores. The 5-year survival rate for exchange of any component was 97.6%, whereby two patients required replacement of the polyethylene gliding surface. Secondary patella resurfacing was performed in 7 patients. Significantly improved results in comparison to the preoperative state could be obtained at the follow-up: KOOS improved from 39.4 to 78.8, SF-12 PCS improved from 32.1 to 42 SF-12 MCS improved from 46 to 53.8 and patella pain improved from 2.7 to 0.3. The mean ROM of the 84 patients after 5 years was 133.1° and mean total KSS was 189.9. This study demonstrates a high survival rate of the Vega PS System® and significant improvements in clinical outcomes 5 years after implantation. The obtained mean ROM indicates that this implant provides good flexibility of the knee joint, allowing a high number of activities. However, due to the rate of secondary patella implantation, routine resurfacing of the patella for all PS TKA cases is highly recommended. The study was registered at clinicaltrials.gov (NCT02802085).