True Confessions of Neutral Mechanical Disciple-How I Learned to Love a Patient-Specific Target.

INTRODUCTION: Classical neutral mechanical alignment in total knee arthroplasty (TKA) has been a standard paradigm, while more recently, other alignment schemas, such as kinematic, individualized, and functional, have been explored. This study aimed to investigate the effect of three-dimensional (3D) computed tomography (CT)-based surgical robotics inputs on a classically trained surgeon's TKA component positions and alignment targets over time. MATERIALS AND METHODS: Data from 1,394 consecutive robotically-assisted TKAs by a single surgeon from 2016 to 2020 were analyzed. Metrics collected included pre-balance planned implant component positions, final planned implant component positions after soft tissue balancing, and constitutional alignment from CT scans. Joint line obliquity was plotted against the arithmetic hip-knee angle (aHKA) using coronal plane alignment of the knee (CPAK). Three categories of alignment strategy were defined: true mechanical alignment (tMA), adjusted mechanical alignment (aMA), and no mechanical alignment (noMA). RESULTS: A shift to overall varus component positioning was observed over the years. Joint line obliquity according to CPAK showed a wider spread in later years, and the distribution of tibial and femoral coronal alignment angles expanded over time. CONCLUSION: The study revealed a change in alignment targets and final positioning of components away from neutral biomechanical axes in a large volume of TKAs by a single, classically trained surgeon over five years of using a robotic arm-assisted TKA system with CT-based planning. The most dominant factor for this change was the use of 3D CT planning, allowing the surgeon to assess patient-specific anatomy and plan accordingly. Outcome data is needed to determine if this change in behavior and surgical technique was beneficial. In summary, using a CT scan-based robotically assisted technique led to a gradual and complete shift from tMA to predominantly a non-mechanically aligned philosophy in TKA.

Results of Robotic-Assisted Versus Manual Total Knee Arthroplasty at 2-Year Follow-up.

Robotic-assisted technology has been developed to optimize the consistency and accuracy of bony cuts, implant placements, and knee alignments for total knee arthroplasty (TKA). With recently developed designs, there is a need for the reporting longer than initial patient outcomes. Therefore, the purpose of this study was to compare manual and robotic-assisted TKA at 2-year minimum for: (1) aseptic survivorship; (2) reduced Western Ontario and McMaster Universities Osteoarthritis Index (r-WOMAC) pain, physical function, and total scores; (3) surgical and medical complications; and (4) radiographic assessments for progressive radiolucencies. We compared 80 consecutive cementless robotic-assisted to 80 consecutive cementless manual TKAs. Patient preoperative r-WOMAC and demographics (e.g., age, sex, and body mass index) were not found to be statistically different. Surgical data and medical records were reviewed for aseptic survivorship, medical, and surgical complications. Patients were administered an r-WOMAC survey preoperatively and at 2-year postoperatively. Mean r-WOMAC pain, physical function, and total scores were tabulated and compared using Student's t-tests. Radiographs were reviewed serially throughout patient's postoperative follow-up. A p < 0.05 was considered significant. The aseptic failure rates were 1.25 and 5.0% for the robotic-assisted and manual cohorts, respectively. Patients in the robotic-assisted cohort had significantly improved 2-year postoperative r-WOMAC mean pain (1 ± 2 vs. 2 ± 3 points, p = 0.02), mean physical function (2 ± 3 vs. 4 ± 5 points, p = 0.009), and mean total scores (4 ± 5 vs, 6 ± 7 points, p = 0.009) compared with the manual TKA. Surgical and medical complications were similar in the two cohorts. Only one patient in the manual cohort had progressive radiolucencies on radiographic assessment. Robotic-assisted TKA patients demonstrated improved 2-year postoperative outcomes when compared with manual patients. Further studies could include multiple surgeons and centers to increase the generalizability of these results. The results of this study indicate that patients who undergo robotic-assisted TKA may have improved 2-year postoperative outcomes.

The Association of Patient and Procedural Factors on Improved Outcomes: A Cluster Analysis on 853 Total Knee Arthroplasty Patients.

Many studies involving robotic-assisted total knee arthroplasty (RATKA) have demonstrated superiority regarding soft tissue balance and consistency with alignment target achievement. However, studies investigating whether RATKA is associated with improved patient outcomes regarding physical function and pain are also important. Therefore, we performed a cluster analysis and examined factors that contributed to differences in patient-reported outcome measures (PROMs). Specifically, we analyzed: (1) reduced WOMAC (rWOMAC) scores regarding pain and function; (2) usage of RATKA; (3) common patient comorbidities; as well as (4) patient demographic factors. The rWOMAC score is an abbreviated PROM that includes pain and physical function domains. This study analyzed 853 patients (95 conventional and 758 robotic-assisted) who had completed preoperative, 6-month, and 1-year postoperative rWOMAC surveys. Two clusters were constructed using rWOMAC pain and function scores at 1 year. Cluster 1 included 753 patients who had better outcomes at 1 year (mean rWOMAC pain = 0.9, mean rWOMAC function = 1.4), and cluster 2 included 100 patients who had worse outcomes at 1 year (mean rWOMAC pain = 7.7, mean rWOMAC function = 10.4). The clusters were compared to determine (1) how scores improved and (2) what patient characteristics were significantly different between clusters. Cluster 1 demonstrated greater improvement from preoperative to 6 months or 1 year (p = 0.0013 for pain preoperative to 6 months, p< 0.0001 for other measures) and 6 months to 1 year (p< 0.0001). Comparisons demonstrated that cluster 1 had older patients (67 vs. 65 years, p = 0.0479) who had lower body mass index or BMIs (31.8 vs. 33.9 kg/m2, p = 0.0042) and no significant differences in sex (p = 0.7849). Cluster 1 also had a significantly higher percentage of RATKA patients (90 vs. 79%, p< 0.001). Cluster analyses provided differentiating factors which were associated with improved postoperative rWOMAC pain and function scores at 1 year. Patients undergoing robotic-assisted TKA were associated with better rWOMAC pain and function scores from preoperative to 6 months and 1 year.

Heterotopic Ossification Prophylaxis Following Operative Fixation of Acetabular Fractures: A Systematic Review.

INTRODUCTION: Heterotopic ossification (HO) is a well-recognized complication following operative fixation of acetabular fractures with a range of severity and clinical consequences. The purpose of this review was to: (1) report the incidence of heterotopic ossification (HO) formation following operative fixation of acetabular fractures; (2) determine the effectiveness of prophylactic treatments for HO; and (3) assess the radiographic severity of HO with and without prophylactic treatment. MATERIALS AND METHODS: A literature search for peer-reviewed articles was conducted utilizing a variety of research databases. PRISMA guidelines were followed and included in this review were full-length, English language manuscripts published before September 2019, using the following search criteria: "heterotopic ossification AND acetabulum OR acetabular." Studies that reported HO as one of the reported outcomes were included. Articles were excluded if radiographic HO was not reported and if it was evaluated in surgeries other than those involved in acetabular fractures. Extracted data included, but was not limited to: type of prophylaxis; incidence of HO; severity of HO based on the Brooker classification; and statistical significance. A methodologic quality appraisal of the included studies was also conducted. A total of 54 full-text studies with 5,890 patients with operatively fixed acetabular fractures met inclusion criteria. There were four level I studies, four level II study, 26 level III studies, and 20 level IV studies. RESULTS: The overall incidence of HO after acetabular fracture surgery was 28.4%. The rate of HO formation was: 34.9% without prophylaxis, 28.3% with non-steroidal anti-inflammatory drugs (NSAID) prophylaxis, and 21.2% with radiation therapy (RT). Patients receiving a combination of both RT and NSAIDs developed HO 21.8% of the time. The rate of radiographic severe HO was 13.9% (range, 0-75%) in patients without prophylaxis, 9.4% (range, 0-50%) with NSAID prophylaxis, 5.7% (range, 0-12.8%) with RT prophylaxis, and 11.7% (range, 0-18.5%) with the combination of RT and NSAIDs. CONCLUSION: With the current literature collected in this systematic review, there was a lower incidence and severity of heterotopic bone formation following acetabular fracture fixation using radiation prophylaxis compared to NSAIDs or no treatment. The available literature is heterogeneous in fracture characteristics, surgical approaches, and prophylactic regimens with a general lack of randomized control trials. Further prospective studies are required to make definitive claims on the optimal prophylactic strategy to prevent heterotopic ossification.

Learning Curve of Robotic-Assisted Total Knee Arthroplasty for a High-Volume Surgeon.

The learning curve has been established for robotic-assisted total knee arthroplasty (RATKA) during the first month of use; however, there have been no studies evaluating this on a longer term. Therefore, the purpose of this study was to compare operative times for three cohorts during the first year following adoption of RATKA (initial, 6 months, and 1 year) and a prior cohort of manual TKA. We investigated both mean operative times and the variability of operative time in each cohort. This is a learning curve study comparing a single surgeon's experience using RAKTA. The study groups were made up of two cohorts of 60 cementless RATKAs performed at ∼6 months and 1 year of use. A learning curve was created based on the mean operative times and individual operative times were stratified into different cohorts for comparison. Study groups were compared with the surgeon's initial group of 20 cemented RATKAs and 60 cementless manual cases. Descriptive numbers were compiled and mean operative times were compared using Student's t-tests for significant differences with a p-value of < 0.05. The mean surgical times continued to decrease after 6 months of RATKA. In 1 year, the surgeon was performing 88% of the RATKA between 50 and 69 minutes. The initial cohort and 1-year robotic-assisted mean operative times were 81 and 62 minutes, respectively (p < 0.00001). Mean 6-month robotic-assisted operative times were similar to manual times (p = 0.12). A significant lower time was found between the mean operative times for the 1-year robotic-assisted and manual (p = 0.008) TKAs. The data show continued improvement of operative times at 6 months and 1 year when using this new technology. The results of this study are important because they demonstrate how the complexity of a technology which initially increases operative time can be overcome and become more time-effective than conventional techniques.

Impact of Parkinson's Disease on Complications, Readmission Rates, and Costs of Care following Primary Total Knee Arthroplasty.

Large-scale studies evaluating the effects of Parkinson's disease (PD) on primary total knee arthroplasty (TKA) are limited. The purpose of this study was to determine if PD patients undergoing primary TKA have increased: (1) medical complications; (2) implant-related complications; (3) readmission rates; and (4) costs. A query was performed using an administrative claims database. The study group consisted of all patients undergoing primary TKA who had a history of PD. Matched non-PD patients undergoing primary TKA served as a control group. The query yielded 72,326 patients (PD = 18,082; matching cohort = 54,244). Pearson's chi-square tests, logistic regression analyses, and Welch's t-tests were used to test for significance between the cohorts. Primary TKA patients who had PD were found to have greater incidences and odds of medical complications (4.21 vs. 1.24%; odds ratio [OR]: 3.50, 95% confidence interval [CI]: 3.15-3.89, p < 0.0001) and implant-related complications (5.09 vs. 3.15%; OR: 1.64, 95% CI: 1.51-1.79, p < 0.0001) compared with the matching cohort. Additionally, the rates and odds of 90-day readmission were higher (16.29 vs. 12.66%; OR:1.34, p < 0.0001) and episodes of care costs were significantly greater ($17,105.43 vs. $15,252.34, p < 0.0001) in patients who had PD. Results demonstrate that PD patients undergoing primary TKA had higher incidences of medical and implant-related complications. They also had increased 90-day readmission rates and costs compared with controls. The findings of this study should be used in risk stratification and should inform physician-patient discussion but should not be arbitrarily used to deny access to care.

The Accuracy of Computed Tomography-Based, Three-Dimensional Implant Planning in Robotic-Assisted Total Knee Arthroplasty.

Advanced imaging used in robotic-assisted total knee arthroplasty (TKA), such as computed tomography (CT)-based three-dimensional (3D) planning, may provide an accurate means of implant sizing preoperatively. The purpose of this study was to examine preoperative CT-based implant planning accuracy for robotic-assisted TKA in patients who have (1) varus deformities, (2) valgus deformities, (3) neutral alignment, and (4) retained hardware. A total of 393 patients underwent a robotic-assisted TKA by a single surgeon received preoperative CT scans. The surgeon reviewed the CT-based model preoperatively and recorded the expected size of the components. The final implants used in each case were recorded and compared with the surgeon's preoperative plan. In all groups of patients, the surgeon's CT-based implant plan was within one size of the implant utilized 100% of the time for both the tibiae and femora. Overall, the surgeon was exactly matched in 319 (81%) and 315 (80%) cases for the femoral and tibial components, respectively. For the femoral component, the mean age for patients in whom the original plan was exactly matched was younger than those whose implants were upsized and older than patients those implants were downsized (p = 0.024). Other patient demographics and preoperative knee alignment were not associated with predictive accuracy for femoral or tibial components. Our results demonstrate how preoperative CT-based, 3D planning for robotic-assisted TKA is accurate to within one size of the components in every case (100%), and exactly matched in 80%. The results of this study are important because they demonstrate how CT-based preoperative implant planning for TKA is reliable and accurate across all native knee alignments and other patient-specific factors. In addition, they build on a previous study by the same single surgeon, demonstrating that predictive ability can improve over time. This may be important as we move toward more outpatient surgery with less ability for prostheses inventory at ambulatory sites.

Total Knee Arthroplasty in the Valgus Knee: Can New Operative Technologies Affect Surgical Technique and Outcomes?

INTRODUCTION: Valgus knee deformities can sometimes be challenging to address during total knee arthroplasties (TKAs). While appropriate surgical technique is often debated, the role of new operative technologies in addressing these complex cases has not been clearly established. The purpose of this study was to analyze the usefulness of computed tomography scan (CT)-based three-dimensional (3D) modeling operative technology in assisting with TKA planning, execution of bone cuts, and alignment. Specifically, we evaluated valgus TKAs performed using this CT-based technology for: (1) intraoperative implant plan, number of releases, and surgeon prediction of component size; (2) survivorship and clinical outcomes at a minimum follow up of one year; and (3) radiographic outcomes. MATERIALS AND METHODS: A total of 152 patients who had valgus deformities receiving a CT-based TKA performed by a single surgeon were analyzed. Cases were performed using an enhanced preoperative planning and real-time intraoperative feedback and cutting tool. The surgeon predicted and recorded implant sizes preoperatively and all patients received implants with initial and final implant alignment, flexion/extension gaps, and full or partial soft tissue releases recorded. A modified Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR.) scores were collected preoperatively and at approximately six months and one year postoperatively. Preoperative coronal alignment ranged from 1 to 13° valgus. Follow-up radiographs were also evaluated for alignments, loosenings, and/or progressive radiolucencies. RESULTS: A total of 96% of cases were corrected to within 3° of mechanical neutral. For outlier cases, initial deformities ranged from valgus 5 to 13°, with final alignment ranging from 4 to 8° valgus (mean 4° correction). Patients had mean femoral internal rotation of 2° and mean femoral flexion of 4°. The surgeon was within one size on the femur and tibia 94 and 100% of the time, respectively. Only one patient required a lateral soft tissue release and one patient had osteophytes removed, which required a medial soft tissue release. Five patients required manipulations under anesthesia. Aside from these, there were no postoperative medical and/or surgical complications and there was 100% survivorship at final follow up. WOMAC and KOOS, JR. scores improved significantly from a mean of 21 ± 9 and 48 ± 10 points preoperatively to 4 ± 6 (p<0.05) and 82 ± 15 (p<0.05) at final follow up, respectively. None of the cases exhibited progressive radiolucencies by final follow up. DISCUSSION: A limitation of this study was not evaluating dynamic kinematics in these patients to determine if rotation had any effects on kinematics. Future studies will evaluate this concern. Nevertheless, the technology successfully assisted with planning, executing bone cuts, and achieving alignment in TKAs complicated by the deformity. This may allow surgeons to predictably avoid soft tissue releases and accurately know component sizes preoperatively, while consistently achieving desired postoperative alignment. CONCLUSIONS: This study demonstrated the utility of CT-based 3D modeling techniques for challenging valgus deformity cases. Use of 3D modeling allowed the TKA components to be positioned according to the patient's anatomy in the coronal, transverse, and sagittal planes. When making these intraoperative implant adjustments, the surgeon may choose to place components outside the preoperative planning guidelines based on the clinical needs of the patient.

Surgical Tray Optimization and Efficiency: The Impact of a Novel Sealed Sterile Container and Instrument Tray Technology.

INTRODUCTION: As bundle payments have begun focusing on orthopaedic procedures, particularly total knee arthroplasties (TKAs), surgeons and hospitals have evaluated methods for improving efficiency. Few studies have investigated the impact of novel, sealed-container and instrument-tray technology on turnover and costs. Therefore, the purpose of this study was to compare traditional and sealed container-sterilized TKA surgical trays by: 1) investigating the setup and clean-down time in the operating room (OR); 2) examining trays processing time in central sterile supply (CS); and 3) estimating OR and CS costs and waste produced. MATERIALS AND METHODS: An interdisciplinary team determined points throughout a TKA tray single-case life cycle that could cause variations in turnover time. The times were recorded for two different TKA tray configurations. Process A utilized instruments housed in vendor trays that were "blue" wrap sterilized, while Process B employed optimized trays that were sealed container-sterilized. Times were recorded during preoperative setup and postoperative clean down in the OR and CS. Reductions in mean OR or CS times were used to estimate cost savings. Wastes were analyzed for each method. Statistical analyses using Student t-tests were used to determine statistical differences and a p-value of less than 0.05 was considered significant. RESULTS: Overall, the use of optimized trays and sealed sterilization containers reduced the turnover time by 57 minutes and the number of trays by a mean of three. OR and CS processing yearly savings were estimated to be $249,245. Waste disposal was an estimated 10,590 ounces and 450 ounces for traditional and sealed containers, respectively. CONCLUSION: Novel sealed sterilization containers demonstrated increased efficiency in the total turnover time of TKA trays. This is important for surgeons participating in bundle payments who perform surgery in a hospital and ambulatory surgery center. Reduced turnover time could potentially increase case load and decrease the need for extra instrumentation or loaner trays. This simple means of increasing efficiency could be used as a model for surgeons wishing to streamline surgical trays and reduce costs.

Estimation of Femoral Version During Total Hip Arthroplasty: Surgeon Visual Assessment versus Robotic-Arm Assisted Technology.

INTRODUCTION: Malposition of THA implants can lead to many complications, some of which may necessitate reoperation. Thus, proper implant placement is critical for optimizing patient outcomes. In addition, intraoperative visual estimation of stem position has been shown to be unreliable. Therefore, the purpose of this study was to compare a surgeon's visual estimation of femoral version to the actual version captured using a three-dimensional robotic-arm assisted platform. MATERIALS AND METHODS: A prospective study of 25 THAs performed by a single surgeon was performed. The mean version, as estimated by intraoperative visual assessment, was compared to that measured by the robotic-arm assisted technology software using a two-sided t-test. Outliers were evaluated for the following intervals: 1 to 5°, 6 to 10°, and greater than 10°. A separate analysis was performed for anteverted versus retroverted stems. RESULTS: The mean version, as estimated by intraoperative visual assessment, was 9.16 ± 4.02° (range, 3 to 18°) compared to 3.52 ± 8.66° (range, -12 to 19) as measured by the robotic-arm assisted software (P=0.005). The surgeon's estimates of broach version and those measured by the robotic-arm assisted software were identical in three cases (12%). The evaluation methods differed by 1 to 5° in six cases (24%), 6 to 10° in 10 cases (40%), and greater than 10° in six cases (24%). Larger differences between methods were noted for cases in which the stem was found to be in anteversion by the robotic-arm assisted software. CONCLUSIONS: Visual estimation of femoral implant version differed significantly from measurements captured by three-dimensional robotic-arm assisted imaging. This suggests that estimating stem position intraoperatively by eye is not reliable, even when done by an experienced surgeon. The use of robotic-arm assisted technology may be recommended for determining femoral stem version intraoperatively.

Computer-Assisted Navigation in Total Knee Arthroplasty.

Manual total knee arthroplasty (TKA) has successfully treated end-stage knee osteoarthritis for several years. However, recent technological advancements have enabled surgeons to perform TKA with more accuracy and precision. Aligning the femoral and tibial components perpendicular to the mechanical axes of the femur and tibia is a fundamental principle for restoring knee kinematics and soft-tissue balance. Computer-assisted robotic TKA has proven its ability to fine tune lower leg alignment, component position, and soft-tissue balancing. Furthermore, robotic-assisted TKA (RATKA) offers the additional benefit of improving soft-tissue protection compared to manual techniques. Numerous systems have been developed in the advancement of technology in computer processing, and the number of robotic surgical systems is increasing as well. The three main categories of navigation systems can be classified as: image-based console navigation, imageless console navigation, and accelerometer-based handheld navigation systems. The purpose of this review was to describe emerging technologies for TKA. Specifically, we outline the available literature pertaining to each system with regards to their: (1) accuracy and precision of component alignment; (2) soft-tissue protection; (3) postoperative outcomes; and (4) other reported outcomes such as costs.

Cementless Fixation for Total Knee Arthroplasty in Various Patient Populations: A Literature Review.

The number of total knee arthroplasties (TKAs) performed in the United States has increased considerably in recent years, with a major contribution from younger patients. Maximizing survivorship of these implants has always been a point of emphasis. Early TKA designs with cementless fixation were associated with high rates of complications and implant failures. However, recent advances in cementless designs have shown excellent results. The decision to use cemented or cementless fixation for patients undergoing TKA is typically based on the surgeon's experience and preference. However, several patient characteristics must also be taken into account. The purpose of this review was to describe the clinical outcomes of studies in which a cementless TKA system was utilized for patients who (1) were less than 60 years of age, (2) were greater than 75 years of age, (3) were obese, (4) had rheumatoid arthritis, and (5) had osteonecrosis of the knee. Based on the studies included in this review, it appears that cementless fixation is a viable option for patients who have all of the above demographics.

Benefits of CT Scanning for the Management of Hip Arthritis and Arthroplasty.

INTRODUCTION: Imaging studies for preoperative planning of total hip arthroplasty (THA) are typically obtained by two-dimensional (2D) anteroposterior radiographs. However, CT imaging has proven to be a valuable tool that may be more accurate than standard radiographs. The purpose of this review was to report on the current literature to assess the utility of CT imaging for preoperative planning of THA. Specifically, we assessed its utility in the evaluation of: 1) hip arthritis; 2) femoral head osteonecrosis; 3) implant size prediction; 4) component alignment; 5) limb length evaluation; and 6) radiation exposure. MATERIALS AND METHODS: A literature search was performed using search terms "computed tomography", "radiograph", "joint" "alignment", "hip," and "arthroplasty". Our initial search returned a total of 562 results. After applying our criteria, 26 studies were included. RESULTS: CT scans were found to be more accurate than radiographs in predicting implant size and alignment preoperatively and provide improved visualization of extraarticular deformities that may be essential to consider when planning a THA. Although radiation is a potential concern, newer imaging protocols have minimized the radiation to levels comparable to x-ray. CONCLUSION: The current literature suggests that CT has several advantages over radiographs for preoperative planning of THA including more accurate planning of implant size, component alignment, and postoperative leg length. It is also superior to x-ray in identifying extraarticular hip deformities using the minimum effective dose for CT and the minimum scan length required by templating software. The radiation can be reduced to values similar to radiography.