Conventional Total Knee Arthroplasty Group Research Articles

Comparison of Time Taken in Conventional versus Active Robotic-Assisted Total Knee Arthroplasty.

Computer- and robotic-assisted total knee replacement procedures have been shown to improve the accuracy of the implant size. It also allows dynamic confirmation of the implant and limb alignment during total knee arthroplasty (TKA). The major inhibition of the arthroplasty surgeon in adapting to the robotic-assisted TKA (RA-TKA) is the extra time spent during the registration process and milling of the bone with the robot. The aim of the study was to ascertain the extra time spent during these 2 steps as compared to the conventional TKA (C-TKA). It is a prospective study involving 30 patients each in the conventional TKA and RA-TKA operated by the same surgical team. The patients were given a choice between the C-TKA and RA-TKA and consecutive 30 cases in each group were studied by an independent observer. In the C-TKA group, the time for the application of appropriate zigs and execution of the bone cuts and soft-tissue release was recorded whereas in the RA-TKA group, the time taken for fixation of the tibial and femoral arrays and bone registration and bone milling with robot and required soft-tissue release was measured. The preoperative patient characteristics were the same in both groups. The time taken in the C-TKA and RA-TKA groups was 24.77 ± 1.92 minutes and 25.03 ± 3.27 minutes, respectively, which is statistically insignificant (p = 0.709). The study findings show that RA-TKA does not take additional time than C-TKA.

Effectiveness of Robotic Arm-Assisted Total Knee Arthroplasty on Transfusion Rate in Staged Bilateral Surgery.

The transfusion rate in staged bilateral total knee arthroplasty (TKA) remains high despite the application of blood management techniques. The potential of robotic arm-assisted TKA (R-TKA) in reducing the transfusion rate in staged bilateral surgery has not yet been investigated. Therefore, we aimed to evaluate the effectiveness of R-TKA on transfusion reduction compared with conventional TKA (C-TKA) in staged bilateral surgery. This retrospective study involved two groups of patients who underwent 1-week interval staged bilateral TKA-the C-TKA group and the R-TKA group-using MAKO SmartRobotics (Stryker, Kalamazoo, MI, USA). Each group comprised 53 patients after propensity score matching and was compared in terms of nadir hemoglobin (Hb) level and transfusion rate after each stage of surgery. Both groups showed no significant differences in the propensity-matched variables of age, sex, body mass index, American Society of Anesthesiologists physical status score, and preoperative Hb level. The R-TKA group showed a significantly higher nadir Hb level than the C-TKA group after the second TKA (p = 0.002). The transfusion rate was not significantly different between the two groups after the first TKA (p = 0.558). However, the R-TKA group showed a significantly lower transfusion rate in the TKA (p = 0.030) and overall period (p = 0.023) than the C-TKA group. Patients who undergo staged bilateral R-TKA have lower transfusion rate than those who undergo C-TKA. R-TKA may be effective in minimizing unnecessary allogeneic transfusions in staged bilateral surgery.

INTRODUCTION OF ROSA ROBOTIC ARM SYSTEM FOR TOTAL KNEE ARTHROPLASTY IS ASSOCIATED WITH A MINIMAL LEARNING CURVE FOR OPERATIVE TIME

The introduction of robotics for total knee arthroplasty (TKA) into the operating theatre is often associated with a learning curve and is potentially associated with additional complications. The purpose of this study was to determine the learning curve of robotic-assisted (RA) TKA within a multi-surgeon team.This prospective cohort study included 83 consecutive conventional jig-based TKAs compared with 53 RA TKAs using the Robotic Surgical Assistant (ROSA) system (Zimmer Biomet, Warsaw, Indiana, USA) for knee osteoarthritis performed by three high-volume (> 100 TKA per year) orthopaedic surgeons. Baseline characteristics including age, BMI, sex and pre-operative Kellgren-Lawrence grade were well-matched between the conventional and RA TKA groups. Cumulative summation (CUSUM) analysis was used to assess learning curves for operative times for each surgeon. Peri-operative and delayed complications were reviewed.The CUSUM analysis for operative time demonstrated an inflexion point after 5, 6 and 15 cases for each of the three surgeons, or 8.7 cases on average. There were no significant differences (p = 0.53) in operative times between the RA TKA learning (before inflexion point) and proficiency (after inflexion point) phases. Similarly, the operative times of the RA TKA group did not differ significantly (p = 0.92) from the conventional TKA group. There was no discernible learning curve for the accuracy of component planning using the RA TKA system. The average length of post-operative follow-up was 21.3 ± 9.0 months. There was no significant difference (p > 0.99) in post-operative complication rates between the groups.The introduction of the RA TKA system was associated with a learning curve for operative time of 8.7 cases. Operative times between the RA TKA and conventional TKA group were similar. The short learning curve implies this RA TKA system can be adopted relatively quickly into a surgical team with minimal risks to patients.

REMOTE EVALUATION OF POSTOPERATIVE OUTCOMES USING WEARABLE SENSORS COMPARING ROBOTIC-ASSISTED AND CONVENTIONAL KNEE ARTHROPLASTY

Patient-reported outcome measures (PROMs) have failed to highlight differences in function or outcome when comparing knee replacement designs and implantation techniques. Ankle-worn inertial measurement units (IMUs) can be used to remotely measure and monitor the bi-lateral impact load of patients, augmenting traditional PROMs with objective data. The aim of this study was to compare IMU-based impact loads with PROMs in patients who had undergone conventional total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), and robotic-assisted TKA (RA-TKA).77 patients undergoing primary knee arthroplasty (29 RA-TKA, 37 TKA, and 11 UKA) for osteoarthritis were prospectively enrolled. Remote patient monitoring was performed pre-operatively, then weekly from post-operative weeks two to six using ankle-worn IMUs and PROMs. IMU-based outcomes included: cumulative impact load, bone stimulus, and impact load asymmetry. PROMs scores included: Oxford Knee Score (OKS), EuroQol Five-dimension with EuroQol visual analogue scale, and the Forgotten Joint Score.On average, patients showed improved impact load asymmetry by 67% (p=0.001), bone stimulus by 41% (p<0.001), and cumulative impact load by 121% (p=0.035) between post-operative week two and six. Differences in IMU-based outcomes were observed in the initial six weeks post-operatively between surgical procedures. The mean change scores for OKS were 7.5 (RA-TKA), 11.4 (TKA), and 11.2 (UKA) over the early post-operative period (p=0.144). Improvements in OKS were consistent with IMU outcomes in the RA-TKA group, however, conventional TKA and UKA groups did not reflect the same trend in improvement as OKS, demonstrating a functional decline.Our data illustrate that PROMs do not necessarily align with patient function, with some patients reporting good PROMs, yet show a decline in cumulative impact load or load asymmetry. These data also provide evidence for a difference in the functional outcome of TKA and UKA patients that might be overlooked by using PROMs alone.

Introduction of ROSA robotic-arm system for total knee arthroplasty is associated with a minimal learning curve for operative time

PurposeThe introduction of robotics for total knee arthroplasty (TKA) into the operating theatre is often associated with a learning curve and is potentially associated with additional complications. The purpose of this study was to determine the learning curve of robotic-assisted (RA) TKA within a multi-surgeon team.MethodsThis prospective cohort study included 83 consecutive conventional jig-based TKAs compared with 53 RA TKAs using the Robotic Surgical Assistant (ROSA) system (Zimmer Biomet, Warsaw, Indiana, USA) for knee osteoarthritis performed by three high-volume (> 100 TKA per year) orthopaedic surgeons. Baseline characteristics including age, BMI, sex and pre-operative Kellgren-Lawrence graded and Hip-Knee-Ankle Axis were well-matched between the conventional and RA TKA groups. Cumulative summation (CUSUM) analysis was used to assess learning curves for operative times for each surgeon. Peri-operative and delayed complications (infection, periprosthetic fracture, thromboembolism, and compromised wound healing) and revisions were reviewed.ResultsThe CUSUM analysis for operative time demonstrated an inflexion point after 5, 6 and 15 cases for each of the three surgeons, or 8.7 cases on average. There were no significant differences (p = 0.53) in operative times between the RA TKA learning (before inflexion point) and proficiency (after inflexion point) phases. Similarly, the operative times of the RA TKA group did not differ significantly (p = 0.92) from the conventional TKA group. There was no discernible learning curve for the accuracy of component planning using the RA TKA system. The average length of post-operative follow-up was 21.3 ± 9.0 months. There was one revision for instability in the conventional TKA group and none in the RA TKA group. There were no significant difference (p > 0.99) in post-operative complication rates between the conventional TKA and RA TKA groups.ConclusionsThe introduction of the RA TKA system was associated with a learning curve for operative time of 8.7 cases. Operative times between the RA TKA and conventional TKA group were similar. The short learning curve implies this RA TKA system can be adopted relatively quickly into a surgical team with minimal risks to patients.

Comparison of femoral sagittal axis between navigated total knee arthroplasty and conventional total knee arthroplasty in patients with knee osteoarthritis.

To compare femoral sagittal axis between navigated total knee arthroplasty (TKA) and conventional TKA.A total of 136 cases were assigned to group 1 (navigated TKA) and 77 cases were assigned to group 2 (conventional TKA). Specifically, this study targeted patients with degenerative osteoarthritis. Only patients with primary TKA were analyzed. Hip knee ankle angle and lateral femoral bowing were measured using preoperative scanogram. Anterior femoral bowing was measured using preoperative femoral lateral X rays. The presence of anterior femoral notching and the insertion angle of the femoral implant with respect to the anatomical sagittal plane of the distal femur were checked using postoperative lateral knee X rays. Student t-test was used to compare the difference in the position of the sagittal plane of the femoral implant between the navigated TKA group and the conventional TKA group.When comparing the 2 groups, the sagittal axis of the femoral implant was more extended than the anatomical sagittal plane axis of the distal femur in group 1 than in group 2 (P = .01). There was a significant negative correlation between the value of anterior femoral bowing and the degree of flexion to the sagittal plane of the femoral implant in group 1 (correlation coefficient: –0.40, P = .01). The occurrence of anterior femoral notching was significantly higher in group 1 than in group 2.During navigated TKA, imageless navigation does not consider the anatomical variation of the femoral shaft. Therefore, surgeons should take into consideration that when performing navigated TKA, a femoral implant could be inserted more extended for the anatomical sagittal axis of the distal femur than for the conventional TKA. Also, surgeon should know that the degree of extension insertion of the femoral implant increases as femoral anterior bowing increases.

Evaluation of Blood Loss in Conventional vs MAKOplasty Total Knee Arthroplasty.

BackgroundPrimary total knee arthroplasty (TKA) has been historically associated with considerable blood loss. Allogenic transfusions, the standard of care for blood loss following TKA, carry inherent risks. With the expanding use of robotic technology in TKA, one theoretical advantage is decreased blood loss and postoperative blood transfusions requirements. The purpose of this study was to compare postoperative hemoglobin levels and the percentage of patients requiring a transfusion of allogenic packed red blood cells after conventional TKA (CTKA) vs robot-assisted TKA (RATKA).MethodsThis is a retrospective review of 486 consecutive patients undergoing either CTKA or RATKA between October 30, 2018, and June 25, 2020, by a single fellowship-trained arthroplasty surgeon. Mako SmartRobotics (Stryker, Kalamazoo, MI) was used for RATKA cases. Primary outcomes included preoperative vs postoperative hemoglobin values and postoperative blood transfusion rates between the 2 groups.ResultsThe mean hemoglobin on postoperative day 1 was 10.7 gm/dl (±1.3) in the CTKA group and 10.9 gm/dl (±1.3) in the RATKA group, P = .24. The largest decline in hemoglobin from preoperative to within 2 days postoperatively was 3.1 gm/dl (±1.1) in the CTKA group and 3.1 gm/dl (±1.1) in the RATKA group, P = .92. The percentage of patients requiring a blood transfusion was 1.1% in the CTKA group and 1.3% in the RATKA group, P = .79.ConclusionsRATKA and CTKA groups did not have significant differences in postoperative hemoglobin changes or the need for postoperative blood transfusions.

Total knee arthroplasty in Ranawat II valgus deformity with enlarged femoral valgus cut angle: A new technique to achieve balanced gap.

BACKGROUNDNearly 10% of patients undergoing primary total knee arthroplasty (TKA) have valgus deformity (VD) of the knee. For severe VD of the knee, a more lateral structural release is needed to achieve balance between medial and lateral space and neutral femorotibial mechanical axis (FTMA), which is challenging and technical.AIMTo introduce a new surgical technique of resection, soft tissue release, and FTMA for Ranawat type-II VD with a 5-year follow-up.METHODSA retrospective study was conducted on patients who underwent TKA from December 2011 to December 2014. Hip-knee-ankle (HKA), range of motion (ROM), Oxford knee score (OKS), and knee society score (KSS) were used to assess the joint activity of patients in the new theory TKA group (NT-TKA) and were compared with those of the conventional TKA group (C-TKA). RESULTSA total of 103 people (103 knees) were included in this study, including 42 patients with an average follow-up period of 83 mo in the C-TKA group and 61 patients with an average follow-up period of 76 mo in the NT-TKA group. Six patients had constrained prosthesis, one had common peroneal nerve injury, and two had joint instability in the C-TKA group, but none of these occurred in the NT-TKA group. There were significant statistical differences in constrained prosthesis usage and complications between the groups (P = 0.002 and P = 0.034, respectively). The KSS at 1 mo post-operation for the C-TKA and NT-TKA groups were 11.2 ± 3.8 and 13.3 ± 2.9, respectively, with a significant difference (P = 0.007). However, the data of HKA, ROM, OKS KSS, and prosthesis survival rate were insignificant (P > 0.05) in both the preoperative and follow-up periods.CONCLUSIONAdopting 5°-7° valgus cut angle for VD and sacrificing 2° neutral FTMA for severe VD which cannot be completely corrected during TKA can reduce the need for soft tissue release, maintain early joint stability, reduce the use of constrained prostheses, and minimize postoperative complications.

A Newly Designed “SkyWalker” Robot Applied in Total Knee Arthroplasty: A Retrospective Cohort Study for Femoral Rotational Alignment Restoration

ObjectiveThis study explored whether robotic arm‐assisted total knee arthroplasty (RATKA) has the advantage of restoring femoral rotational alignment compared to conventional total knee arthroplasty (COTKA).MethodsSixty patients (45 women and 15 men) attending our department from May 2019 to December 2020 were selected and divided into two groups, with 30 patients in each group, according to whether they underwent COTKA or RATKA. Femoral rotational alignment results, such as, posterior condylar angle (PCA), patella transverse axis‐femoral transepicondylar axis angle (PFA), radiological findings, such as, hip‐knee‐ankle angle (HKA), lateral distal femoral angle (LDFA), and medial proximal tibial angle (MPTA), and operative data (operation time, intraoperative blood loss, tourniquet time, and length of stay (LOS), and clinical outcomes, such as maximum knee flexion angle (MKFA), Knee Society Score (KSS), and Western Ontario Mac Master University Index Score (WOMAC) were compared within and between the two groups.ResultsPCA and PFA in the RATKA group were (0.6 ± 0.3)° and (0.9 ± 0.3)°, respectively, which were smaller than (1.5 ± 2.0)° and (3.1 ± 1.1)° in the COTKA group (P < 0.05), and were closer to 0°; the differences in HKA, LDFA, and MPTA were not statistically significant. With the exception of the LDFA, the HKA, MPTA, PCA, and PFA improved in both groups after surgery (P < 0.05). The blood loss and the LOS of RATKA group were 192.3 ± 23.1 mL and 8.2 ± 1.4 days, which were less than 203.7 ± 29.8 mL and 9.3 ± 1.1 days of the COTKA group, but the operation time showed no statistically significant difference, and the tourniquet time was longer (P < 0.05). The MKFA in the RATKA group was (123.0 ± 3.7)°, which was greater than (116.3 ± 4.6)° in the COTKA group (P < 0.05). In terms of scores, the postoperative results were better than the preoperative results in both groups (P < 0.05). However, there was no statistically significant difference between the groups.ConclusionThe accuracy of femoral rotational alignment reconstructed achieved by RATKA is significantly better than that of COTKA and is more conducive to the recovery of knee flexion function after surgery; although RATKA reduces intraoperative blood loss and postoperative LOS, the short‐term clinical efficacy comparison has not yet demonstrated the advantages of robotic technology, and a more optimized design is needed to improve the efficiency of RATKA surgery.

Robot-assisted (RA) versus conventional total knee replacement: a 2-year clinical comparison

Background: Robotic-assisted (RA) technology is becoming increasingly popular in total knee arthroplasty (TKA) due to its improved alignment, accuracy, and precision compared with the conventional TKA. Despite reported benefits, disagreements exist regarding patient-reported outcomes and complication rates comparing RA TKA and conventional TKA. Thus, the purpose of the study is to report differences in patient outcomes and complication rates between patients who underwent RA versus conventional TKA. Methods: The authors retrospectively reviewed 239 primary knee arthroplasty cases (n=137 robot-assisted and n=102 conventional TKA) performed by a single fellowship-trained orthopaedic surgeon from January 1, 2016 to February 26, 2019. The electronic medical record and patient outcomes database were reviewed for demographic characteristics (age, sex, body mass index, and comorbidities), patient-reported outcomes (Short Form Health Survey and Oxford Knee Score), 90-day complications, and revision rates. Results: There was no statistically significant difference in patient-reported outcomes between conventional versus RA groups at two time points: preoperative and 2-year. Differences remained insignificant after controlling for age, sex, body mass index, and comorbidities. There was no statistically significant difference between the conventional and RA groups in revision rates (0.7% and 1%, respectively; P=1.00) or complication rates (1.5% and 3.9%, respectively; P=0.406). Conclusions: There were no differences in 90-day complications, revisions, and patient-reported outcome scores between RA TKA and conventional TKA groups at short-term follow-up. Surgeons can expect similar clinical outcomes without an increase in complications while taking advantage of increased accuracy in alignment and component placement. Further long-term study of RA TKA outcomes is warranted. Level of Evidence: Level III.

HURWA robotic-assisted total knee arthroplasty improves component positioning and alignment - A prospective randomized and multicenter study.

BackgroundThe objective of this study was to compare the radiologic and clinical outcomes of HURWA robotic-assisted total knee arthroplasty (TKA) to those of conventional TKA.MethodsA total of 150 patients were randomized into two groups – 73 and 77 patients underwent robotic-assisted TKA and conventional TKA, respectively. Preoperative and postoperative Western Ontario McMaster University Osteoarthritis Index (WOMAC) score, Hospital for Special Surgery (HSS) score, 36-item Short Form Health Survey (SF-36) score, Knee Society Score (KSS) and range of motion (ROM) were obtained and compared between these two groups. The preoperative and postoperative hip-knee-ankle (HKA) angle and the rate of HKA≤3° in the two groups were also compared.ResultsThe postoperative mean HKA angle was 1.801° ​± ​1.608° of varus for the robotic-assisted TKA group and 3.017° ​± ​2.735° of varus for the conventional TKA group; these values were significantly different. The alignment rate for mechanical axis lower than 3° in the robotic-assisted TKA group and the conventional TKA group were 81.2% and 63.5%, respectively. Patients undergone robotic-assisted TKA or conventional TKA had similarly improved knee flexion and functional recovery reflected by WOMAC score, HSS score, SF-36 score and KSS.ConclusionHURWA robotic-assisted TKA is a safe and effective, resulting in better alignment for mechanical axis than conventional TKA. The improvement in knee flexion and functional recovery after HURWA robotic-assisted TKA were similar to those after conventional TKA. However, longer follow-up is needed to determine whether the improved alignment of mechanical axis will produce better long-term clinical outcomes.The translational potential of this articleRecently, the robotic-assisted TKA system has been introduced to clinical practice for TKA. Several robotic-assisted TKA systems, including CASPAR, Tsolution, ROSA, ROBODOC and Mako, have been implemented into clinical application.However, the clinical application of these robotic systems was limited due to their technical complexity, insufficient versatility and increased operative time. Until now, there are still no robotic-assisted TKA systems approved by the National Medical Products Administration of China. Therefore, more robotic-assisted TKA systems need to be designed and improved, particularly in China. Through our randomized, multicenter, single blind and parallel controlled trial, we showed that HURWA robot-assisted TKA system is a safe and effective system for TKA, which had improved knee flexion.

Postoperative radiologic outcome comparison between conventional and computer-assisted navigation total knee arthroplasty in extra-articular tibia vara

Total knee arthroplasty (TKA) is the definite treatment for osteoarthritis. Meanwhile, significant inherent extra-articular varus angulation is associated with abnormal postoperative hip-knee-ankle (HKA) angle. Computer-assisted navigation TKA (CAS-TKA) used in patients who have severe varus deformity. The purpose of this study was to compare postoperative radiologic outcome between CAS-TKA and conventional TKA for extra-articular tibia vara. A retrospective review of postoperative HKA on standing lower extremity views was conducted in patients who underwent TKA by a single surgeon from 2010 to 2018, including knee with conventional TKA (n = 83) and CAS-TKA (n = 246). Extra-articular tibia vara was assessed by measuring the metaphyseal-diaphyseal angle (MDA) of the tibia in preoperative standing lower extremity view. Postoperative alignment was assessed by measuring the HKA in postoperative standing lower extremity view. There was no significant difference in age (p = 0.063), gender (p = 0.628), body mass index (p = 0.426), preoperative range of motion (p = 0.524), preoperative HKA (p = 0.306), preoperative MDA (p = 0.523), or postoperative HKA (p = 0.416) between the two groups (conventional TKA and CAS-TKA). There was no significant difference in postoperative alignment for cases with MDA ≤4° (p = 0.351) or MDA >4° (p = 0.866) in each group. There was a positive correlation between preoperative HKA and postoperative HKA in the CAS-TKA group (p < 0.001, r = 0.243). However, there was no significant correlation between preoperative HKA and postoperative HKA in the conventional TKA group (p = 0.732). There was no significant difference in postoperative alignment between conventional TKA and CAS-TKA in extra-articular tibial vara even for cases with MDA >4°.

Robotic versus conventional primary total knee arthroplasty: clinical and radiological long-term results with a minimum follow-up of ten years

The aim of this study was (1) to compare the clinical and radiological outcomes of robotic and conventional total knee arthroplasty with a minimum follow-up of tenyears, (2) to evaluate the survival rate, (3) and to estimate the accuracy of the two techniques by analyzing the outliers of the total knee arthroplasty (TKA) patients. We evaluated 351 patients (390 knees), 155 patients undergoing robotic TKA, and 196 patients treated with conventional TKA with a mean follow-up of 11.0years. HSS, KSS, WOMAC, and SF-12 questionnaires were used for clinical evaluation. Mechanical alignment, implant radiological measurements, and outliers were analyzed for radiological results. Kaplan-Meier survival analysis was performed for survival rate. All clinical assessments showed excellent improvements in both groups (all p < 0.05), without any significant difference between the groups (p > 0.05). The conventional TKA group showed a significantly higher number of outliers compared with the robotic TKA group (0 < 0.05). The cumulative survival rate was 98.8% in the robotic TKA group and 98.5% in the conventional TKA group with excellent survival (p = 0.563). Our study showed excellent survival with both robotic and conventional TKA and similar clinical outcomes at long-term follow-up. And, in terms of radiological outcome, robotic TKA showed better accuracy and consistency with fewer outliers compared with conventional TKA. With longer follow-up and larger cohort, the accuracy and effectiveness of robotic TKA on implant survival rate can be elucidated in the future.

Short-term effectiveness of total knee arthroplasty assisted by three-dimensional printing osteotomy navigation template

To investigate the short-term effectiveness of total knee arthroplasty (TKA) assisted by three-dimensional (3D) printing osteotomy navigation template. A retrospective study was performed on 60 patients with osteoarthritis bewteen January 2016 and June 2017. Thirty cases underwent TKA assisted by 3D printing osteotomy navigation template (3D printing group) and 30 cases underwent the conventional TKA (conventional TKA group). There was no significant difference in gender, age, body mass index, surgical side, and disease duration between 2 groups ( P>0.05). The operation time, the pre- and post-operative hemoglobin values, the amount of drainage, the Hospital for Special Surgery (HSS) score and Knee Society Score (KSS) of knee joint before operation and at 3 months after operation were observed. And 6 freedom degrees of knee (the varus and valgus angle, the internal and external rotation angle, the antero-posterior displacement, the proximal-distal displacement, the flexion and extension angle, and the internal and external displacement) before operation and at 3 months after operation were recorded by Opti-Knee (the knee 3D motion analysis system). The values of 2 groups were compared with 30 healthy adults (<60 years). The operation time was shorter in 3D printing group than that in conventional TKA group ( t=5.833， P=0.000). The hemoglobin values at 1 and 3 days after operation were higher in 3D printing group than those in conventional TKA group ( P<0.05). The amount of drainage was less in 3D printing group than that in conventional TKA group ( t=5.468， P=0.000). All patients were followed up 6-9 months (mean, 7.3 months). There was no significant difference in pre- and post-operative HSS score and KSS clinical score between 2 groups ( P>0.05). There was no significant difference in preoperative KSS function score between 2 groups ( P>0.05), but the KSS function score of 3D printing group at 3 months after operation was higher than that of conventional TKA group ( P<0.05). Before operation, the varus and valgus angle, the internal and external rotation angle, the antero-posterior displacement, the proximal-distal displacement of 3D printing group and conventional TKA group were larger than that of the healthy adults ( P<0.05); there was no significant difference in the flexion and extension angle and the internal and external displacement between 2 groups and healthy adults ( P>0.05). At 3 months after operation, compared with healthy adults, the varus and valgus angle of conventional TKA group was increased, the flexion and extension angle of conventional TKA group was decreased ( P<0.05); the proximal-distal displacement and the internal and external displacement of 2 groups were decreased ( P<0.05); there was no significant difference in other freedom degrees between groups ( P>0.05). No sign of prosthesis loosening was observed by X-ray examination. Compared with the traditional TKA, TKA assisted by the 3D printing osteotomy navigation template had such advantages as shorter operation time, less postoperative blood loss, and well postoperative recovery.

Navigated versus conventional total knee arthroplasty: A prospective study at three years follow-up

ObjectiveComputer-assisted surgery application in total knee arthroplasty (TKA) has shown more accurate implant alignment compared with conventional instrumentation and is associated with more homogeneous alignment results. Although longer implant survival and superior clinical outcomes should be expected from navigated TKA, currently available evidence does not support this hypothesis. The aim of this study was to compare navigated TKA with conventional TKA regarding clinical and radiological outcomes after a 3-year follow-up under the hypothesis that navigated TKA would provide better outcomes than conventional TKA. Material and methodIn a prospective multicentre study, 119 patients underwent navigated TKA and 80 patients received conventional instrumentation. Patients were evaluated at the baseline and at postoperative months 3, 12, 24, and 36. Analysis included the American Knee Society Score (KSS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Short Form-12 (SF12) Health Survey, and radiographic assessment. ResultsAll clinical scores improved significantly for all patients during the follow-up but were significantly better in the navigation group.The percentage of patients showing a mechanical axis between 3° of varus and 3° of valgus was significantly higher in the ATR group (93%) than in the conventional TKA group (71%) (p<.01). ConclusionsThe use of computer-assisted surgery in TKA provides more accurate mechanical alignment and superior short-term functional outcomes compared to conventional TKA.

Alignment in total knee arthroplasty — A comparison of patient-specific implants with the conventional technique

BackgroundIncorrect positioning and malalignment of total knee arthroplasty (TKA) components can result in implant loosening. Restoration of neutral alignment of the leg is an important factor affecting the long-term results of TKA. The aim of our retrospective study was to compare mechanical axis in patients with conventional and patient-specific TKAs. Methods232 patients who underwent TKA between January 2013 and December 2014 were included to compare postoperative mechanical axis. 125 patients received a patient-specific TKA (iTotal CR®, Conformis) and 107 a conventional TKA (Triathlon®, Stryker). Standardized pre- and postoperative long-leg standing radiographs were retrospectively evaluated to compare the two patient cohorts. Results113 (90%) radiographs of patient-specific TKA and 88 (82%) of conventional TKA were available for comparison. The preoperative deviation from neutral limb axis was 9.0° (0.1–27.3°) in the patient-specific TKA cohort and 8.2° (0.2–18.2°) in the conventional TKA group. Postoperatively the patient-specific TKA group showed 3.2° (0.1–8.4°) and the conventional TKA cohort 2.3° (0.1–12.5°) deviation. However, the rate of ±3° outliers from neutral limb axis was 16% in the patient-specific TKA cohort and 26% in the conventional TKA group. ConclusionsPatient-specific TKA demonstrated fewer outliers from neutral leg alignment compared to conventional technique. Potential benefits in the long-term outcome and functional improvement require further investigation.

Artroplastia total de rodilla navegada versus convencional; estudio prospectivo a 3 años de seguimiento

ObjectiveComputer-assisted surgery application in total knee arthroplasty (TKA) has shown more accurate implant alignment compared with conventional instrumentation and is associated with more homogeneous alignment results. Although longer implant survival and superior clinical outcomes should be expected from navigated TKA, currently available evidence does not support this hypothesis. The aim of this study was to compare navigated TKA with conventional TKA regarding clinical and radiological outcomes after a 3-year follow-up under the hypothesis that navigated TKA would provide better outcomes than conventional TKA. Material and methodIn a prospective multicentre study, 119 patients underwent navigated TKA and 80 patients received conventional instrumentation. Patients were evaluated at the baseline and at postoperative months 3, 12, 24, and 36. Analysis included the American Knee Society Score (KSS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Short Form-12 (SF12) Health Survey, and radiographic assessment. ResultsAll clinical scores improved significantly for all patients during the follow-up but were significantly better in the navigation group.The percentage of patients showing a mechanical axis between 3° of varus and 3° of valgus was significantly higher in the ATR group (93%) than in the conventional TKA group (71%) (P<.01). ConclusionsThe use of computer-assisted surgery in TKA provides more accurate mechanical alignment and superior short-term functional outcomes compared to conventional TKA.

Effects of Femoral Lateral Bowing on Coronal Alignment and Component Position after Total Knee Arthroplasty: A Comparison of Conventional and Navigation-Assisted Surgery.

PurposeTo evaluate the effects of femoral lateral bowing on coronal alignment after total knee arthroplasty (TKA) and examine whether the use of navigation helps obtain better postoperative coronal alignment and component position.Materials and MethodsRadiological results and outlier rates were compared between the conventional TKA group and the navigation-assisted TKA group, and factors associated with postoperative alignment were evaluated. For clinical assessment, patient-reported outcomes were used.ResultsA total of 297 knees were retrospectively reviewed. Among the patients with femoral lateral bowing, a significant difference was observed between the conventional TKA group (n=72) and the navigation-assisted TKA group (n=96) in postoperative mechanical femorotibial angle (mFTA, 1.6° vs. 0.8°; p=0.005) and femoral component alignment angle (89.0° vs 90.0°; p=0.017). Preoperative mFTA (p<0.001), femoral bowing angle (p<0.001), and mechanical lateral distal femoral angle (p=0.032) had effects on postoperative mFTA in the conventional TKA group. In the navigation-assisted TKA group, only preoperative mFTA (p<0.001) had effects on postoperative mFTA.ConclusionsDespite the individualized determination of the valgus correction angle through preoperative planning, in the cases with severe lateral bowing, the outlier rate was higher in the conventional TKA group than in the navigation-assisted TKA group. However, there was no significant difference in the clinical results between the two groups in the short-term follow-up.

Kneeling and standing up from a chair as performance-based tests to evaluate knee function in the high-flexion range: a randomized controlled trial comparing a conventional and a high-flexion TKA design

BackgroundWe compared the functional outcome between conventional and high-flexion total knee arthroplasty (TKA) using kneeling and sit-to-stand tests at 1 year post-operative. In addition, the patient’s daily functioning, pain and satisfaction were quantified using questionnaires.MethodsWe randomly assigned 56 patients to receive either a conventional or a high-flexion TKA. Primary outcomes were maximum flexion angle and maximum thigh-calf contact measured during kneeling at 1 year post operatively. Secondary outcomes were the angular knee velocity and ground reaction force ratio measured during sit-to-stand performance tests, and questionnaires.ResultsAt one year post-operative, maximum knee flexion during kneeling was higher for the high-flexion TKA group (median 128.02° (range 108–146)) compared to the conventional TKA group (119.13° (range 72–135)) (p = 0.03). Maximum thigh-calf contact force was higher for the high flexion TKA group (median 17.82 N (range 2.98–114.64)) compared to the conventional TKA group (median 9.37 N (range 0.33–46.58))(p = 0.04). The sit-to-stand tests showed a significantly higher angular knee velocity in the conventional TKA group (12.12 rad/s (95%CI 0.34–23.91); p = 0.04). There were no significant differences between groups in ground reaction force ratios and patient-reported outcome scores.ConclusionAlthough no differences were found in patient-reported outcome scores, differences in performance-based tests were clearly apparent. Standing up from a chair at 90° of knee flexion appeared to be easier for the conventional group. The kneeling test revealed significantly higher weight-bearing knee flexion for the high-flex group. Hence, if kneeling is an important activity for a patient a high-flex design may be recommendable.Trial registrationThe study was retrospectively registered in ClinicalTrials.gov under identifier NCT00899041 (date of registration: May 11, 2009).

Alignment and component position after patient-matched instrumentation versus conventional total knee arthroplasty.

To compare patient-matched instrumentation (PMI) with conventional total knee arthroplasty (TKA) in terms of limb alignment and component position. Nine men and 36 women (mean age, 69.5 years) who underwent PMI TKA were compared with 20 men and 25 women (mean age, 69.3 years) who underwent conventional TKA by the same team of surgeons with the same prosthesis and protocols in terms of limb alignment and component position using the Perth protocol computed tomography, as well as bone resection measurements, operating time, and the number of trays used. The PMI and conventional TKA groups were comparable in terms of age, body mass index, tourniquet time, operating time, and the number of trays used. For limb alignment and component position, the 2 groups differed significantly in sagittal femoral component position (2.4º vs. 0.9º, p=0.0008) and the percentage of knees with femoral component internally rotated ≥1° with respect to the transepicondylar axis (20% vs. 55%, p=0.001). The difference was not significant in terms of limb alignment, coronal and rotational femoral component position, or coronal and sagittal tibial component position. Intra-operatively, all patient-matched cutting blocks demonstrated acceptable fit and stability. No instrument-related adverse events or complications were encountered. One (2.2%) femur and 6 (13.3%) tibiae were recut 2 mm for optimal ligament balancing. Two femoral components were upsized to the next size, and 2 tibial components were upsized and 2 downsized to the next size. PMI was as accurate as conventional instrumentation in TKA. There was no significant difference in limb alignment or femoral and tibial component position in the coronal and sagittal planes between PMI and conventional TKA. PMI had a higher tendency to achieve correct femoral component rotation.