Total Knee Arthroplasty System Research Articles

Are asymmetric designs of tibial components superior to their symmetric counterparts for constrained condylar total knee arthroplasty using metal block augmentation?

PurposeIn total knee arthroplasty (TKA), asymmetric tibial components have been developed alongside symmetric tibial components to enhance bony coverage at the tibia. In primary TKA and revision TKA for patients with significant bone defects, augmentation is employed to fill the bone defect. However, there have been no reports on bony coverage of the tibial component of the revision system in the cases of bone defects. Therefore, we simulated bone defects using CT and compared the bony coverage of asymmetric and symmetric tibial components in the revision TKA system.MethodsThis study included 45 patients (50 knees involved) with medial osteoarthritis. Preoperative CT scans were used to simulate placement using ZedKnee. Three models were evaluated: Persona Revision PCCK (Zimmer) for the asymmetric component, NexGen LCCK (Zimmer) for the symmetric component, and the ATTUNE revision system (Depuy-Synthes). A 130-mm stem extension was utilized. Augmentations of each thickness were placed to simulate bone defects of 5, 10, and 15 mm. The coverage, overhang, and underhang rates were measured for each slice and compared among the models.ResultsIn terms of coverage, the rate was greater for PCCK at 0 mm, and only ATTUNE exhibited a significantly lower coverage at 5 and 10 mm. There was no significant difference in coverage at 15 mm. At 0 mm, PCCK demonstrated less posterior underhangs. At 5 and 10 mm, PCCK showed less anterior overhang but more anterior underhang. At 15 mm, PCCK had a less anterior overhang, with an overhang in the posterior region but less underhang. When overhang and underhang were combined and compared, the asymmetric component generally yielded superior results.ConclusionIn the cases of bone defects, asymmetric components demonstrated reduced anterior overhang and decreased posterior underhang, resulting in greater bone coverage. This may contribute to improved long-term outcomes in the revision TKA system.

Radiolucent lines and revision risk in total knee arthroplasty using the conventional versus the Attune S+ tibial baseplate.

This multicentre retrospective observational study's aims were to investigate whether there are differences in the occurrence of radiolucent lines (RLLs) following total knee arthroplasty (TKA) between the conventional Attune baseplate and its successor, the novel Attune S+, independent from other potentially influencing factors; and whether tibial baseplate design and presence of RLLs are associated with differing risk of revision. A total of 780 patients (39% male; median age 70.7 years (IQR 62.0 to 77.2)) underwent cemented TKA using the Attune Knee System) at five centres, and with the latest radiograph available for the evaluation of RLL at between six and 36 months from surgery. Univariate and multivariate logistic regression models were performed to assess associations between patient and implant-associated factors on the presence of tibial and femoral RLLs. Differences in revision risk depending on RLLs and tibial baseplate design were investigated with the log-rank test. The conventional and novel Attune baseplates were used in 349 (45%) and 431 (55%) patients, respectively. At a median follow-up of 14 months (IQR 11 to 25), RLLs were present in 29% (n = 228/777) and 15% (n = 116/776) of the tibial and femoral components, respectively, and were more common in the conventional compared to the novel baseplate. The novel baseplate was independently associated with a lower incidence of tibial and femoral RLLs (both regardless of age, sex, BMI, and time to radiograph). One- and three-year revision risk was 1% (95% CI 0.4% to 1.9%)and 6% (95% CI 2.6% to 13.2%), respectively. There was no difference between baseplate design and the presence of RLLs on the the risk of revision at short-term follow-up. The overall incidence of RLLs, as well as the incidence of tibial and femoral RLLs, was lower with the novel compared to the conventional tibial Attune baseplate design, but higher than in the predecessor design and other commonly used TKA systems.

Are all robotic technologies created equal? Comparing one of the latest image-free robotic technologies to all other robotic systems for total knee arthroplasty

BackgroundRobotic-assisted technologies have been developed to increase surgical precision and reduce surgical variability in total knee arthroplasty (TKA). Several different robotic systems have been introduced in the last decade for TKA. The DePuy Synthes VELYS™ Robotic-Assisted Solution (VRAS) is an imageless system designed to eliminate the need for preoperative CT scans and is one of the latest entrants in the rapidly evolving field of robotic technology in TKA. This study compared the clinical and economic outcomes associated with VRAS and other robotic-assisted technologies for primary TKA.MethodsA retrospective cohort study using the Premier Healthcare Database included patients who underwent primary TKA with VRAS or other robotic-assisted technologies from January 1, 2022, to April 30, 2023. The primary outcome for the study was hospital follow-up visits (revisits) within 90 days post-TKA. Secondary outcomes included readmission and revision rates within 90 days post-TKA, operating room time, length of stay, discharge status and hospital costs. Cohorts were balanced using propensity score fine stratification, and generalized linear models were constructed to evaluate outcomes.ResultsThis study included 827 VRAS TKA patients and 16,428 TKA patients treated with other robotic-assisted technologies. The 90-day all-cause and knee-related revisit rates were significantly lower for VRAS than for other robotic-assisted technologies (all-cause 13.9% vs. 22.8% and knee-related 2.8% vs. 5.4%, respectively; p value < 0.01). The all-cause and knee-related 90-day readmission rates were also lower for VRAS, although the differences were not statistically significant. The 90-day revision rates were similar for VRAS and other robotic-assisted technologies (0.48% vs. 0.45%), as was the operating room time (138 vs. 137 min). The 90-day knee-related cost for the VRAS cohort was $15,048 compared to $16,867 for other robotic technologies.ConclusionsThis database study demonstrated that early postoperative revisit rates and total cost of care are lower for VRAS than for all other robotic-assisted technologies for TKA, while operating room time and discharge status were similar. These are important findings in ever-evolving healthcare systems that are increasingly cost conscious and cognizant of principles associated with value-based care.

The Influence of Preimplant Balancing on Manipulation under Anesthesia Rates following Imageless Robotic-Assisted Total Knee Arthroplasty.

Acquired idiopathic stiffness (AIS) following total knee arthroplasty (TKA) often requires manipulation under anesthesia (MUA). Robotic-assisted TKA (RA-TKA) systems provide gap balance templates for objective correlation with the rate of AIS. The purpose of this study was to assess intraoperative balancing parameters that were associated with MUA utilizing an "anatomical" implant design.We performed a retrospective chart review of 265 imageless RA-TKA procedures performed by R.M. and K.D. between 2018 and 2020. The primary outcome for AIS or clinically significant "arthrofibrosis" was MUA. Patient intraoperative gap planning data were examined for association.The rate of MUA was 8.7% (23/265), which was performed at a mean follow-up time of 75.9 ± 32.2 days. The lateral to medial gap difference in extension was significantly less in patients requiring MUA (odds ratio [OR] = 0.86, 95% confidence interval [CI], 0.75-0.99) (p = 0.034). Significantly less preoperative varus mechanical axis was associated with knees requiring MUA (1.83° vs. 4.04°, OR = 1.09, 95% CI, 1.00-1.19). Decreased templated mechanical axis correction was associated with MUA (2.09° vs. 4.75°, p < 0.0001).A tighter lateral-to-medial gap in extension, less preoperative varus, and smaller templated mechanical axis corrections were associated with increased rates of MUA.

Application of remote sensing navigation system in total knee arthroplasty

To explore clinical accuracy of remote sensing navigation alignment (RSNA) system in total knee arthroplasty (TKA) and its influence on postoperative clinical efficacy. From May 2021 to May 2022, 60 knee osteoarthritis (KOA) patients with Kellgren-Lawrence (K-L) grade Ⅲ to Ⅳ treated by unilateral primary TKA were selected and divided into RSNA group and traditional operation group according to treatment methods, and 30 patients in each group. There were 6 males and 24 females in RSNA group, aged from 55 to 86 years old with an average of (68.06±8.23) years old;body mass index (BMI) ranged from 22.15 to 34.58 kg·m-2 with an average of (28.20±3.01) kg·m-2;the courses of disease ranged from 2 to 60 months with an average of (18.80±14.80) months;13 patients with grade Ⅲ and 17 patients with grade Ⅳ according to K-L grading. In traditional operation group, there were 8 males and 22 females, aged from 57 to 85 years old with an average of (67.26±6.32) years old;BMI ranged from 23.94 to 34.55 kg·m-2 with an average of (27.49±2.32) kg·m-2;the courses of disease ranged from 3 to 60 months with an average of (21.30±16.44) months;14 patients with grade Ⅲ and 16 patients with grade Ⅳ according to K-L grading. Western Ontario and McMaster Universities (WOMAC) osteoarthritis index and Knee Society score(KSS) were used to evaluate functional recovery of patients. Hip-knee-ankle angle (HKAA), distal femoral valgus angle (FVA) and distal fermoral flexion angle (DFFA) were measured before operation. HKAA and HKAA deviation angle were measured at 1 week after operation, and defective rate of lower limb force line, femur prosthesis valgus angle (FPVA) and femoral prosthesis flexion angle (FPFA), respectively, were calculated. There were no serious complications such as vascular and nerve injury during operation, and wound healed at stage Ⅰ. Both groups were followed up for 6 months. There were no significant difference in WOMAC index, KSS, HKAA, FVA and DFFA between two groups before operation (P>0.05). The force line defect rate, HKAA, HKAA deviation angle, FPVA deviation angle and FPFA of RSNA group were 6.7%, (178.74±1.56) °, (1.25±1.56) °, (1.84±0.16) ° and (4.85±2.46) °, respectively;while in traditional operation group were 20%, (176.73±3.46) °, (3.27±3.46) °, (2.44±0.26) °, (6.60±1.86) °;the difference between two groups were statistically significant (P<0.05). There were no significant difference in WOMAC index and KSS between two groups at 3 and 6 months after operation (P>0.05). RSNA system could reduce defective rate of lower limb force line, FPVA deviation angle and FPFA after TKA, which is more accurate and easy to operate than traditional intramedullary localization surgery while ensuring postoperative efficacy.

Long term follow-up of a completely metal free total knee endoprosthesis in comparison to an identical metal counterpart

Aseptic loosening is a feared and not yet fully-understood complication of total knee arthroplasty (TKA). Hypersensitivity reactions may be the underlying cause within some susceptible patients. Metal-free implants have been developed as a possible solution. The aim of this prospective, observational long-term study was the assessment of a completely metal-free ceramic knee replacement system compared to its identical metal counterpart 8 years after implantation, conducted as a follow-up of a previous report. A total of 88 patients (mean age 69 years) were enrolled in this prospective, observational long-term 8-year follow-up study. The “ceramic group” with a completely metal-free total knee replacement system was compared to the “conventional group” with an identical metal TKA system at the final follow-up. Clinical assessment included Knee Society Score (KSS), Oxford Knee Score (OKS), European Quality of Life 5 Dimensions 3 Level Version (EQ-5D-L), European Quality of Life 5 Dimension Visual Analogue Scale (EQ-VAS) and High Activity Arthroplasty Score (HAAS) as well as perioperative or postoperative complications and need for revision. The tibial/femoral positioning, signs of periprosthetic fissures/fractures or radiolucent lines were documented radiographically. All postoperative clinical scores in the ceramic group primarily improved from baseline to 4-year follow-up, but then decreased at the final 8-year follow-up. At the final follow-up, statistically non-significant differences were found in comparison of both groups for the KSS (ceramic: 166 ± 31, conventional: 162 ± 29; p > 0.05), OKS (ceramic: 37, conventional: 39; p > 0.05), EQ-VAS (ceramic: 77 ± 17, conventional: 72 ± 18; p > 0.05), and HAAS (ceramic: 8.29 ± 3.32, conventional: 9.28 ± 4.44; p > 0.05). A significant difference was found for EQ-5D-L (ceramic: 0.819 ± 0.284, conventional: 0.932 ± 0.126; p ≤ 0.05). Progressive radiolucent lines have been found around the uncemented tibial stem (0.8 mm at initial diagnosis (mean 19 months); 1.3 mm at 4-year follow-up; 1.6 mm at 8-year follow-up) without any clinical signs of loosening. One revision surgery was performed after a traumatic polyethylene inlay-breakage. No allergic reactions could be detected. The used ceramic TKA system meets the functional performance standards of an established identical metal TKA system after an 8-year follow-up period, offering a safe option for patients with prior hypersensitivity reactions to metallic materials. Full cementation of ceramic components is recommended.

Clinical outcomes and radiolucent line analysis in cementless mobile-bearing total knee arthroplasty: a prospective multicentre study in Japan

The objective of this study was to assess radiolucent lines (RLLs) and to determine their effect on clinical outcomes of the newly introduced cementless mobile-bearing total knee arthroplasty (TKA) system. This was prospective, multicentre study. Seventy-eight patients with knee osteoarthritis who underwent primary TKA were enrolled. Patient-reported outcome measures (PROMs) and radiographic assessments were evaluated at preoperative baseline and at 6 weeks, 1 year, and 2 years after surgery. KOOS, PKIP, 2011KSS, EQ-5D-3L and SKO improved from preoperative baseline to all postoperative timepoints, with no loosening of components. No RLLs were detected at 6 weeks after surgery. However, RLLs ≥ 1 mm developed in 2.8% of the patients for the femur and 9.7% for the tibia at 1 year after surgery, and values were 5.7% and 10.9%, respectively, at 2 years after surgery. RLL incidence was not correlated with PROMs. Age, sex, body mass index, range of motion knee flexion, posterior cruciate ligament treatment and β angle did not impact the occurrence of RLLs. There were no intraoperative complications, revisions or reoperations. This TKA system improved PROMs and showed less incidence of RLLs compared to the previous reported TKA without implant-related complications.

The use of a modern robotic system for the treatment of severe knee deformities.

Robotic-assisted total knee arthroplasty (TKA) have shown promising results in recent years with improved clinical outcomes using standard primary implants. The purpose of this study was to assess the experience of a single center in correcting severe coronal deformities with the use of a robotic-assisted TKA system and an increased constrained implant. Between July 2020 and December 2022, 30 knees in 28 patients with a major deformity and an associated ligament laxity requiring an increased constrained implant treated using an imageless robotic-assisted TKA were prospectively enrolled. Patients included in the study showed a minimum 15 degrees varus or 10 degrees valgus deviation. 20 cases were varus knees and 10 cases were valgus knees. Postoperative neutral alignment was defined as 0∘± 2.5∘. A CCK implant was used in 20 cases while a Constrained Posterior Stabilized implant was used in 10 cases. A neutral alignment was achieved in all patients. At a minimum 6 months follow up (f-u 6-30 months) clinical outcomes including ROM, KSS, HSS, OKS and WOMAC showed significant improvement and no major complications were registered. The robotic system showed the achievement of a mechanical alignment with reliable radiographic outcomes and clinical results in the treatment of major deformities of the lower limb with the use of higher constrained implants at short term follow up. Further follow up and studies are necessary to confirm and verify these promising outcomes.

The Role of a New Hinged Total Knee Arthroplasty System for Use in a Variety of Complex Knee Scenarios: A Case Series.

Hinged knee arthroplasties are commonly used in scenarios where there are major ligament deficiencies or bone loss around the knee. They are applicable in native knees with major deformities and during revisions. They can also be used as a salvage procedure after distal femoral resection. The new modular hinged device system, namely the Triathlon Hinge Knee (THK) System (Stryker, Mahwah, New Jersey), reflects the advancements of third-generation design and enhances surgical flexibility by allowing streamlined integration with the Triathlon Total Stabilized (TS) System (Stryker, Mahwah, New Jersey) and the Global Modular Replacement System (GMRS, Stryker, Mahwah, New Jersey). Additionally, the Triathlon Revision Tibial Baseplate (Stryker, Mahwah, New Jersey) has been launched as part of THK and is compatible with the Modular Rotating Hinge (MRH , Stryker, Mahwah, New Jersey) femur, which allows the Revision Baseplate to replace the existing tibial component while leaving the existing MRH Femoral Component in place. The Triathlon Revision Tibial Baseplate enables orthopaedic surgeons to use constrained or hinged prostheses, including both distal and total femoral replacement options, without changing the Tibial Baseplate. This is because the TS, MRH, THK, and GMRS femurs are compatible with the new Triathlon Revision Tibial Baseplate. Additionally, the system can be augmented with metaphyseal cone constructs to help provide a stable foundation for reconstruction. This report explores the application of a new modular hinged device system in various scenarios, starting with (1) complex primary hinged knee arthroplasty, followed by revision hinged knee arthroplasty cases including (2) failed TKA with medial collateral ligament (MCL) dysfunction, (3) severe arthrofibrosis post-TKA, (4) revisions for prosthetic joint infection, (5) extensor mechanism deficiency, and (6) arthrofibrosis with extensor mechanism disruption, concluding with a case of (7) distal femoral arthroplasty for periprosthetic fracture post-failed TKA.

Functional and radiological outcomes of total knee arthroplasty using posterior-stabilized U2 knee system: A retrospective study in 560 cases at five years of follow-up.

The purpose of this study was to assess clinical and functional outcomes as well as the prosthesis survival rates of the U2 Knee system in primary total knee arthroplasty (TKA) with a minimum follow-up of four years. We retrospectively analyzed 560 consecutively primary TKA performed between 2015 and 2019 due to osteoarthritis with a mean follow-up of 5.4 ± 1.1years. The clinical outcomes were assessed using the knee society score (KSS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Radiographic outcomes were assessed using the American knee society's roentgenographic evaluation system. Prosthetic survival was calculated using the Kaplan-Meier method. Postoperative KSS showed significant improvement at one year (Clinical: 37.4 ± 4.1 vs. 91.9 ± 3.7; p < 0.01; Functional: 41.2 ± 3.3 vs. 90.6 ± 4.8; p = < 0.01), with these improvements maintained throughout the follow-up period. The WOMAC score improved from 60 ± 10.1 preoperatively to 10.9 ± 8.3 (p = 0.02) at the end of the follow-up. There were 20 (3.7%) knees with radiolucent lines around the implant (< 2mm), and none showed evidence of loosening. There were six (1.1%) revisions-four due to prosthetic joint infections and two due to periprosthetic femur fracture. The prosthetic survival was 97.8% at the study closure. The U2 knee system demonstrates effective and safe performance for primary TKA with significant improvements in functional scores, patient-reported outcomes, and a promising prosthesis survival rate at mid-term follow-up. We will continue with the series analysis to assess the long-term outcomes.

Initiation of a novel text messaging system in total knee and hip arthroplasty

BackgroundThe primary objective of this study was to investigate whether using a novel text messaging system improves patient overall satisfaction compared to standard care. Secondary objectives included assessing the impact of the text messaging system on decreasing narcotic usage, the number of emergency department visits, the range of flexion and extension, and number of telephone calls to the surgeon’s office.MethodsWe enrolled 217 patients to either receive informative text messages (text messaging group, n = 86) or no additional text messages (conventional group, n = 131). Patients self-reported results on a questionnaire at the 6-week follow-up regarding the primary and secondary objectives. The active range of motion of total knee arthroplasty patients was recorded by the surgeon or treating physiotherapist.ResultsThere was no significant difference in overall satisfaction (P = 0.644), narcotic cessation (P = 0.185), range of motion (Flexion P = 0.521; Extension P = 0.515), and emergency department visits (P = 0.650) between the two groups. There was a statistically significant decrease in surgeon office calls favoring the text messaging group (P = 0.029). A subgroup analysis revealed that the statistical difference was mainly in the TKA group (P = 0.046).ConclusionsA novel text messaging system may help reduce the work burden by decreasing telephone calls to the surgeon’s office. While satisfaction, narcotic usage, emergency department visits, and range of motion did not significantly differ, patients endorsed the system for friends/family.

Assessment of preoperative planning and intraoperative accuracy of the AIKNEE system for total knee arthroplasty

BackgroundThe aim of this retrospective study was to evaluate the effectiveness and accuracy of the AIKNEE system in preoperative planning and intraoperative alignment for total knee arthroplasty (TKA).MethodsA total of 64 patients were planned preoperatively by the AIKNEE system, including the measurement of mechanical femorotibial angle (mFTA), lateral distal femoral angle (LDFA), and medial proximal tibial angle (MPTA) using three-dimensional reconstructed images. Intraoperatively, the actual prosthesis size and alignment were compared to the planned parameters. Postoperative outcomes, including pain levels, range of motion (ROM), and Knee Scoring System (KSS) scores, were assessed after surgery. Statistical analyses were performed to evaluate the correlation between alignment deviations and postoperative function.ResultsThe AIKNEE system accurately predicted the prosthesis size in thirty-one of femoral cases (48%) and forty-seven of tibial cases (73%). Deviations of mFTA, LDFA, and MPTA from the target value were within 3° in 88%, 92%, and 95% of cases, respectively. A significant improvement was observed in postoperative pain, ROM, and KSS scores (p < 0.001). Correlation analysis revealed that greater deviations in mFTA and LDFA were associated with increased pain (p = 0.004, 0.047) and lower KSS scores (p = 0.027).ConclusionThe AIKNEE system demonstrated promising results in predicting prosthesis size and achieved alignment within the desired range in a majority of cases. Postoperative outcomes, including pain levels and functional improvement, were favorable.

Revisiting the universal femoral component: Midterm outcomes of a modern design

IntroductionApproximately 10 years ago a total knee arthroplasty system with a modern universal femoral component was introduced. It includes a symmetrical femoral and tibial component. The purpose of this study was to evaluate the 6-year clinical outcomes of this implant from a single surgeon. Materials and methodsA retrospective chart review was performed on all patients who received a TJO Klassic® Knee from January 2014 to January 2015 (Total Joint Orthopedics Inc., Salt Lake City, Utah). In total there were 131 patients (149 knees) who underwent total knee arthroplasty with this system. A retrospective chart review was performed including demographics, preoperative and postoperative clinical assessments including Knee Society score (KSS), range of motion, and radiographic assessment. ResultsThere were 60 males (45.8 %) and 71 females (54.2 %) with 149 knees available for review. Mean age at time of surgery was 67.4 years (45–91) and BMI was 32.6 kg/m2 (16.6–54.6). The patella was left unresurfaced in 37 knees (24.8 %), KSS scores including the clinical and functional components all improved significantly (p < 0.001). ROM improved significantly (p < 0.001). 9 knees underwent reoperation within 6 years of their index operation: 2 quadriceps tendon repairs, 3 polyethylene exchanges for laxity, 2 two-stage revisions for infection, 1 revision for aseptic loosening of the femur, and 1 for post-traumatic patella fracture. Conclusion6-year outcomes of a modern universal femoral design demonstrate excellent clinical results and survivorship equal to modern asymmetrical femur designs. There were no known instances of patellar maltracking.

Development and clinical validation of a deep learning-based knee CT image segmentation method for robotic-assisted total knee arthroplasty.

This study aimed to develop a novel deep convolutional neural network called Dual-path Double Attention Transformer (DDA-Transformer) designed to achieve precise and fast knee joint CT image segmentation and to validate it in robotic-assisted total knee arthroplasty (TKA). The femoral, tibial, patellar, and fibular segmentation performance and speed were evaluated and the accuracy of component sizing, bone resection and alignment of the robotic-assisted TKA system constructed using this deep learning network was clinically validated. Overall, DDA-Transformer outperformed six other networks in terms of the Dice coefficient, intersection over union, average surface distance, and Hausdorff distance. DDA-Transformer exhibited significantly faster segmentation speeds than nnUnet, TransUnet and 3D-Unet (p<0.01). Furthermore, the robotic-assisted TKA system outperforms the manual group in surgical accuracy. DDA-Transformer exhibited significantly improved accuracy and robustness in knee joint segmentation, and this convenient and stable knee joint CT image segmentation network significantly improved the accuracy of the TKA procedure.

Cementless Total Knee Arthroplasty: A State-of-the-Art Review.

» The demographic profile of candidates for total knee arthroplasty (TKA) is shifting toward younger and more active individuals.» While cemented fixation remains the gold standard in TKA, the interest is growing in exploring cementless fixation as a potentially more durable alternative.» Advances in manufacturing technologies are enhancing the prospects for superior long-term biological fixation.» Current research indicates that intermediate to long-term outcomes of modern cementless TKA designs are comparable with traditional cemented designs.» The selection of appropriate patients is critical to the success of cementless fixation techniques in TKA.» There is a need for high-quality research to better understand the potential differences and relative benefits of cemented vs. cementless TKA systems.

Third-generation posterior-stabilised cemented system for total knee arthroplasty: Survivorship and outcomes after 20-year follow-up.

Total knee arthroplasty is a common procedure due to increased life expectancy and ageing populations, necessitating implants with long-term efficacy. After some initial designs, the third-generation modular posterior-stabilised NexGen® prosthesis aimed to enhance kinematics and reduce complications. This study evaluates the long-term outcomes, survivorship, revision rates and complications of this implant. With promising results observed up to 15 years in previous studies, this investigation aims to assess the implant's performance over extended follow-up periods, aiding in optimal implant selection for improved patient outcomes. We carried out a retrospective study on 263 total knee arthroplasties performed in our centre between 1998 and 2002. Statistical analysis of complications was performed and study of survival using the Kaplan-Meier method and competing risk analysis were calculated. Description of reinterventions and complications were also included. Results show a 20-year prosthesis survival rate of 90.8% for revision due to any reason, with an estimated survival of 92.3% considering competitive events. Estimated survivorship at 20 years is 98% for aseptic loosening as the end point, and an estimation of 98.80% considering competitive events. Twenty revisions were performed, with 10 cases due to infection and 10 for noninfectious reasons and three of them due to aseptic loosening. Radiographic analysis revealed radiolucent lines, but no clinical evidence of loosening was observed in these cases. This study offers survivorship data from longer follow-up periods, what is difficult to find in the reported literature and showed excellent results of this implant in terms of survivorship and low rates of revision in our cohort. Level IV.

Evaluating the accuracy of a new robotically assisted system in cadaveric total knee arthroplasty procedures

BackgroundRobot-assisted total knee arthroplasty (TKA) has been shown to facilitate high-precision bone resection, which is an important goal in TKA. The aim of this cadaveric study was to analyze the accuracy of the target angle and bone resection thickness of a recently introduced robotic TKA system.MethodsThis study used 4 frozen cadaveric specimens (8 knees), 2 different implant designs, navigation, and a robotic system. The 4 surgeons who participated in this study were trained and familiar with the basic principles and operating procedures of this system. The angle of the bone cuts performed using the robotic system was compared with the target angles from the intraoperative plan. For each bone cut, the resection thickness was recorded and compared with the planned resection thickness.ResultsThe mean angular difference for all specimens was less than 1°, and the standard deviation was less than 2°. The mean difference between the planned and measured angles was close to 0 and not significantly different from 0 except for the difference in the frontal tibial component angle, which was 0.88°. The mean difference in the hip-knee-ankle axis angle was − 0.21°± 1.06°. The mean bone resection difference for all specimens was less than 1 mm, and the standard deviation was less than 0.5 mm.ConclusionsThe results of the cadaveric experimental study showed that the new TKA system can realize highly accurate bone cuts and achieve planned angles and resection thicknesses. Despite the limitations of small sample sizes and large differences between cadaveric and clinical patients, the accuracy of cadaveric experiments provides strong support for subsequent clinical trials.

Complications and Learning Curve Associated with an Imageless Burr-Based (CORI) Robotic-Assisted Total Knee Arthroplasty System: Results from First 500 Cases.

The use of robotic-assisted total knee arthroplasty (RA-TKA) is gaining traction. There is evidence to suggest that RA-TKA can help to optimize the precision and accuracy of implant positioning and that there may be protective effects on surrounding bony and soft tissues. Yet, there are important differences between the various RA-TKA systems currently on the market. One such newly introduced RA-TKA system uses imageless technology and performs bony cuts with the use of a burr-based device. The learning curve and complications unique to this system have yet to be assessed. We evaluated 500 consecutive RA-TKA cases using a newly developed burr-based and imageless system which were done by a single surgeon between the months of October 2021 and February 2023. Operative times were recorded and compared to the previous 150 conventional TKA cases allowing for the learning curve to be calculated using the CUSUM method. Intraoperative and postoperative complications were categorically profiled. The learning curve of this RA-TKA system was found to be 6 cases. Intraoperative complications included unintended bony over resection (n = 3), soft tissue injury (n = 2), and robotic system hardware (n = 2) or software (n = 2) malfunction. Postoperative complications consisted of superficial pin site infection (n = 1) and periprosthetic fracture near the pin sites (n = 1). There were no identified cases of prosthetic joint infection, instability events, or wound complications. The learning curve and the complication profile of a newly introduced imageless and burr-based RA-TKA system were described. This information serves to guide surgeons in adopting this technology and can counsel them regarding the potential pitfalls and challenges associated with its integration into practice. The work sheds light on the complexity and learning curve of the recently released imageless burr-based RA-TKA system. This important information is intended to help surgeons accept this cutting-edge technology by providing advice on any errors and difficulties that can occur when integrating it into clinical practice. This information can help surgeons navigate the complexities of integrating this new burr-based robotic technology into knee replacement procedures, enabling them to make well-informed decisions and receive guidance.

High in-vivo accuracy of a novel robotic-arm-assisted system for total knee arthroplasty.

Robotic-assisted total knee arthroplasty (TKA) has been shown to improve the accuracy and precision of bony resections and implant position. However, the in vivo accuracy of the full surgical workflow has not been widely reported. The primary objective of this study is to determine the accuracy and precision of a robotic-arm-assisted system throughout the intraoperative workflow. This was a retrospective cohort study of adult patients who underwent primary TKA with various workflows and alignment targets by three arthroplasty-trained surgeons with previous experience using the ROSA® Knee System (Zimmer Biomet) over a 3-month follow-up period. Accuracy and precision were determined by measuring the difference between various workflow time points, including the final preoperative plan (PP), robot-validated (RV) resection angleand postoperative radiographs (PR). The absolute mean difference between the measurements determined accuracy, and the standard deviation represented precision. The lateral distal femoral angle, medial proximal tibial angle, femoral flexion angle and tibial slope were measured on postoperative coronal long-leg radiographs and true short-leg lateral radiographs. A total of 77 patients were included in the final analyses. The accuracy for the coronal femoral angle was 1.62 ± 1.11°, 0.75 ± 0.79°and 1.96 ± 1.29° for the differences between PP and PR, PP and RVand RV and PR. The tibial coronal accuracy was 1.44 ± 1.03°, 0.81 ± 0.67°and 1.57 ± 1.14° for PP/PR, PP/RVand RV/PR, respectively. Femoral flexion accuracy was 1.39 ± 1.05°, 0.83 ± 0.59°and 1.81 ± 1.21° for PP/PR, PP/RVand RV/PR, respectively. Tibial slope accuracy was 0.99 ± 0.72°, 1.19 ± 0.87°and 1.63 ± 1.11°, respectively. The proportion of patients within 3° was 93.2%, 95.3%, 97.3%and 94.6% for the distal femur, proximal tibia, femoral flexionand tibial slope angles when the final intraoperative plan was compared to PRs. No patients had a postoperative complication at the final follow-up. The ROSA Knee System has acceptable accuracy and precision of coronal and sagittal plane resections with few outliers at various steps throughout the platform's entire workflow in vivo. Level III.

The Vega advanced third generation posterior stabilized total knee arthroplasty system enables the restoration of range of motion for high demanding daily activities - A 5-years follow-up study.

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).