Tibial Component Size Research Articles

Correlation between Component Size and Functional Knee Score in Patients Undergoing Bilateral Simultaneous Total Knee Arthroplasty: A Cross-Sectional Study

Abstract Background: Simultaneous bilateral total knee arthroplasty (simBTKA) has been a favored surgical solution to reduce costs and patient suffering. We aimed to evaluate the rate of asymmetry of component size in patients undergoing simBTKA and its impact on knee function as we believe that implant asymmetry may affect the functional outcomes in those patients. Methods: A cross-sectional study design was done on on 60 patients (120 knees) with simBTKA using patient-specific templating (PST). Patients were included if they had Kellgren–Lawrence Grade III-IV osteoarthritis. Revision surgeries, staged BTKA, or patients with bone defects, valgus deformity, severe varus deformity (defined as above 20°), and extra-articular deformities were excluded from the study. The outcome measures were interlimb component asymmetry, Knee Society Score (KSS), and range of motion (ROM). The comparison between pre- and postoperative findings was done using a dependent t-test. Results: A total of 29 (48.34%) patients had symmetrical femoral and tibial components, whereas the rest had asymmetry, of them, 11.7% had both femoral and tibial component size asymmetry. There were no statistically significant differences between the changes in KSS and ROM in the smaller implant and larger implant groups (P = 0.5 and P = 0.4, respectively). The total number of complications was eight and as follows: superficial infection, aseptic loosening, rupture of the patellar tendon after a bathroom fall, anemia requiring blood transfusion, residual varus deformity, deep venous thrombosis, periprosthetic fracture, and malalignment. Conclusion: There is no correlation between the interlimb component asymmetry and the knee function. However, there was statistically significant improvement from preoperative to postoperative KSS and ROM in small and large implants.

KINEMATIC ALIGNMENT TECHNIQUE IN TOTAL KNEE ARTHROPLASTY CHANGES FEMORAL SIZING

Introduction: Kinematic alignment (KA) is an innovative approach designed to restore natural knee kinematics in Total Knee Arthroplasty (TKA). Unlike traditional mechanical alignment (MA), which focuses on aligning the femur and tibia along a mechanical axis, KA considers the three axes governing the movement of the patella and tibia relative to the femur. This difference leads to variations in femoral sizing between the two techniques. KA has shown to significantly reduce femoral size compared to MA in TKA patients. Material and Methods: This retrospective study analyzed the records of 323 patients who underwent TKA from 2017 to 2024. Patients were divided into two groups: 177 received KA, and 146 received MA. Data on femoral and tibial component sizes were collected. The primary objective was to compare differences in femoral and tibial sizing between the groups. The mean difference in femoral size was calculated. Demographic data were used to predict the expected femoral size for a subset of patients, comparing predicted to actual sizes. Discrepancies were analyzed between KA and MA groups. Results: Femoral sizing differed significantly between groups. In the KA group, 10.7% needed a smaller femoral size than tibial, 51.4% had equal sizes, and 37.9% needed a larger femoral size. In the MA group, 1.3% needed a smaller femoral size, 28.8% had equal sizes, and 69.9% needed a larger femoral size (p<0.001). The mean femoral size difference was significant: 0.29 for KA and 0.62 for MA (p<0.001). KA more often resulted in a smaller-than-predicted femoral size than MA (68.7% vs. 53.6%, p<0.05). Conclusions: This study highlights the significant impact of KA on femoral sizing in TKA. KA leads to a greater proportion of patients requiring smaller femoral components compared to MA. The substantial difference in femoral sizing distributions between the groups (p<0.001) underscores the importance of considering alignment techniques in preoperative planning and component selection for TKA.

An observational study on the functional outcomes of 100 robotic total knee replacements performed by an Indian surgeon: Early experiences

Abstract Background: We aim to share our preliminary encounter with robotic knee replacements in Indian patients, focusing on the initial 100 cases. This report will delve into our observations regarding the learning curve and provide insights from a short-term follow-up at 6 months. Materials and Methods: Following institutional ethical clearance, we conducted an observational study involving 100 robotic-assisted total knee replacement cases performed from March 2022 to November 2022. These patients underwent a 6-month follow-up to evaluate functional outcomes. Our primary objective was to investigate the learning curve associated with robotic-assisted total knee arthroplasty (RATKA), specifically emphasizing operative time. Furthermore, we examined preoperative and postoperative alignment parameters as part of our analysis. Results: In our investigation, participants had a mean age of 64.68 years, with a female-to-male ratio of 43:22 and an average body mass index of 30.71 ± 4.88. Intraoperative blood loss was recorded at an average of 91.81 ± 21.63 mL. The mean surgical duration for the initial 25 cases was 102.5 ± 11.08 min, which improved to 65.65 ± 13.07 min for the subsequent 75 cases. The average hospital stay length was 2.88 ± 0.88 days. Notably, there was a significant enhancement in the Knee Society Score (KSS), with a preoperative mean of 38.90 ± 12.72 improving to a postoperative mean of 84.89 ± 4.10 (P = 0.001), as well as in the Oxford Knee Score (OKS), which saw a rise from 16.62 ± 16.42 preoperatively to 45.58 ± 4.97 postoperatively (P = 0.001). The accuracy of preoperative determination for femoral component sizes was 100%, while for tibial component sizing, it was 97%. Conclusion: The key finding from this observational study suggests that around 25 procedures are required to reach a learning plateau. During this process, an average decrease of 36.1 min in surgical time was observed from the initial to proficient stages. Notably, no learning curve was observed for lower limb alignment and implant placement, and no significant complication rates were documented.

Preoperative predictors of implant size in patients undergoing total knee arthroplasty: a retrospective cohort study

BackgroundTraditionally, the size of total knee arthroplasty (TKA) components is predicted by preoperative radiographic templating, which is of limited accuracy. This study aimed to evaluate the role of demographic data and ankle volume in predicting implant size in TKA candidates.MethodsIn a retrospective study, 415 patients who underwent TKA at a single institution were included. The mean age of the patients was 67.5 ± 7.1 years. The mean BMI of the patients was 31.1 ± 4.7 kg/m2. TKA implants were Zimmer Biomet NexGen LPS-Flex Knee in all cases. The demographic data included age, sex, height, weight, BMI, ethnicity, and ankle volume. Ankle volume was assessed with the figure-of-eight method. Multivariate linear regression analysis was used for predicting factors of implant size.ResultsMultivariate linear regression analysis showed that the Sex (β:1.41, P < 0.001), height (β:0.058, P < 0.001), ankle volume (β:0.11, P < 0.001), and Age (β:0.017, P = 0.004) were significant predictors of tibial component size. Sex (β:0.89, P < 0.001), height (β:0.035, P < 0.001), and ankle volume(β:0.091, P < 0.001) were significant predictors of femoral component size in the multivariate analysis.ConclusionDemographic data, adjunct with the ankle volume, could provide a promising model for preoperative prediction of the size of tibial and femoral components in TKA candidates.

Tibial Component Undersizing Is Related to High Degrees of Implant Migration Following Cementless Total Knee Arthroplasty: A Study of Radiostereometric Analysis Data for 111 Patients with 2-Year Follow-up.

A total of 111 patients who underwent TKA surgery with a cementless tibial component were followed for a period of 2 years postoperatively, during which implant migration was assessed with use of RSA. RSA was performed within 7 days postoperatively and after 3, 6, 12, and 24 months. Postoperative radiographs were evaluated for component size and placement in the tibia. The evaluations were performed by experienced knee surgeons who were blinded to the migration data and clinical outcomes. A multivariable linear regression analysis was conducted. Continuous implant migration (i.e., migration occurring between 12 and 24 months postoperatively) had a negative association with tibial component size (coefficient [B], -0.2; 95% confidence interval [CI], -0.33 to -0.08). Subsidence was associated with the absence of posterior cortical bone support (B, -0.7; 95% CI, -1.09 to -0.28), the absence of lateral cortical bone support (B, 0.8; 95% CI, 0.29 to 1.37), frontal-plane varus malalignment (B, 0.6; 95% CI, 0.12 to 1.16), and component undersizing (B, -0.4; 95% CI, -0.06 to -0.68). Posterior tilt was associated only with undersizing (B, 0.6; 95% CI, 0.27 to 1.11). Undersized cementless tibial components are at a higher risk for poor fixation with continuous migration following TKA. Therefore, a higher risk of aseptic loosening should be expected. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Prognostic Factors in Staged Bilateral Total Knee Arthroplasty-A Retrospective Case Series Analysis.

Bilateral osteoarthritis of the knee is an indication for a bilateral total knee replacement (TKR) procedure. The goal of our study was to assess the sizes of the implants used during the first and second stages of TKR procedures in order to compare their size and identify the prognostic factors for the second procedure. We evaluated 44 patients who underwent staged bilateral TKR procedures. We assess the following prognostic factors from the first and second surgery: duration of anesthesia, femoral component size, tibial component size, duration of hospital stay, tibial polyethylene insert size, and the number of complications. All assessed prognostic factors did not differ statistically between the first and second TKR. A strong correlation was found between the size of femoral components and the size of tibial components used during the first and second total knee arthroplasty. The mean duration of the hospital stay associated with the first TKR surgery was 6.43 days, whereas the mean duration of the second hospital stay was 5.5 days (p = 0.211). The mean sizes of the femoral components used during the first and second procedures were 5.43 and 5.2, respectively (p = 0.54). The mean sizes of the tibial components used during the first and second TKR procedures were 5.36 and 5.25, respectively (p = 0.382). The mean sizes of the tibial polyethylene inserts used during the first and second procedures were 9.45 and 9.34 (p = 0.422), respectively. The mean duration of anesthesia during the first and second knee arthroplasty was 117.04 min and 118.06 min, respectively (p = 0.457). The mean rates of recorded complications associated with the first and second TKR procedures were 0.13 and 0.06 per patient (p = 0.371). We observed no differences between the two stages of treatment in terms of all analyzed parameters. We observed a strong correlation between the size of femoral components used during the first and second total knee arthroplasty. We noted a strong correlation between the size of tibial components used during the first and second procedure. Slightly weaker prognostic factors include the number of complications, duration of anesthesia and tibial polyethylene insert size.

Medial tibial plateau fracture following unicompartmental knee arthroplasty – characteristics, risk factors, pathogenesis and treatment methods. Literature review and case report

Introduction. Medial tibial plateau fracture (MTPF) after medial unicompartmental knee arthroplasty (UKA) is a rare but significant complication. Materials and methods. MEDLINE, ScienceDirect and Cochrane Library databases were searched using specific search terms. The inclusion criteria were articles in English, medial unicompartmental knee arthroplasty intraoperative or stress MTPF, reported patients’ demographics and fracture characteristics, the treatment process, any case with a follow-up for a minimum of 3 months and the reported outcome. The exclusion criteria were lateral tibial plateau fracture, traumatic injury, all cases with a follow-up shorter than 3 months and no reported outcome. Results. From 374 records initially found, 36 were included in the analysis highlighting the characteristics, causes and mechanisms of UKA-related MTPF. As to the treatment outcomes, only 10 studies with a total of 19 cases met our inclusion and exclusion criteria. What was also reported was a case report of a 52-year-old patient diagnosed with MTPF one week after UKA and treated using ORIF with support plate and bone augmentation. At the 8-month follow-up, the patient was complaint-free and received 88 points in the KOOS Score. Conclusions. Several measures were proposed in the literature to minimize the risk of UKA-related MTPF. One of them is appropriate patient selection (BMI, BMD). As to the operative technique, positioning tibial pins too close to the medial tibial cortex and tibial plateau, extending the sagittal and vertical cut, damaging the posterior cortex and using excessive force during hammering should be avoided. In addition, the proper tibial component size and placement (considering the gender, race and knee alignment) is also important. UKA-related MTPF was reported to be managed with either conservative treatment, ORIF or revision to total knee arthroplasty (TKA). While conservative treatment carries a high risk of failure, and the revision to TKA is a massive procedure associated with the removal of all UKA components, ORIF was reported to bring favorable outcomes, being less invasive than revision to TKA.

Efficacy of the Pre-operative Three-Dimensional (3D) CT Scan Templating in Predicting Accurate Implant Size and Alignment in Robot Assisted Total Knee Arthroplasty.

Nearly 20% of Total knee Arthroplasty patients remain dissatisfied. This is a major concern in twenty-first century arthroplasty practice. Accurate implant sizing is shown to improve the implant survival, knee balance and patient reported outcome. Aim of the current study is to assess the efficacy of pre-operative three-dimensional (3D) CT scan templating in a robot-assisted TKA in predicting the correct implant sizes and alignment. Prospectively collected data in a single center from 30 RA-TKAswas assessed. Inclusion criterion was patients with end stage arthritis (both osteoarthritis and rheumatoid arthritis) undergoing primary TKA. Patients undergoing revision TKA and patients not willing to participate in the study were excluded. Preliminary study of ten patients had indicated almost 100% accuracy in determining the implant size and position. Sample size was estimated to be 28 for 90% reduction in implant size and position error with α error of 0.05 and beta error of 0.20 with power of study being 80. Post-operative radiographs were assessed by an independent observer with respect to implant size and position. The accuracy of femoral and tibial component sizing in the study was compared with the historic control with Chi-squared test. The p value < 0.05 was considered significant. The pre-operative CT scan 3D templating accuracy was 100% (30 out of 30 knees) for femoral component and 96.67% (29 out of 30 knees) for tibial component. The implant position and limb alignment was accurate in 100% of patients. The accuracy of femoral component and tibial component sizing is statistically significant (Chi-squared test, p value 0.0105 and 0.0461, respectively). The study results show the effectiveness of pre-operative 3 D CT scan planning in predicting the implant sizes and implant positioning. This may have a potential to improve the implant longevity, clinical outcomes and patient satisfaction.

What is the best way for an inexperienced surgeon to learn total ankle arthroplasty?

BackgroundPrevious reports on the learning curve of total ankle arthroplasty (TAA) revealed that inexperienced surgeons should be more careful about operative indications and procedures during the learning curve period. Patients who underwent surgery with inexperienced surgeons may be associated with inferior clinical outcomes, such as frequent complications. This study aimed to evaluate the effect of the participation of experienced surgeons as assistants on the results of TAA performed by inexperienced surgeons. MethodsSurgeons whose experience in performing TAA included less than 15 ankles were defined as inexperienced surgeons; on the other hand, those whose experience included more than 20 ankles were defined experienced surgeons in this study. Thirteen ankles operated by inexperienced surgeons, with an experienced surgeon who participated as an assistant, were assigned to the inexperienced group. Fifteen ankles operated on by an experienced surgeon were assigned to the experienced group. TNK Ankle (Kyocera, Kyoto, Japan) was used for all experiments.The coronal and sagittal alignments and the size of the tibial component relative to the tibial shaft were measured. Preoperative and postoperative Japanese Society for Surgery of the Foot (JSSF) and the Self-Administered Foot Evaluation Questionnaire (SAFE-Q) were used for clinical assessment. ResultsThere were two malleolar fractures during the operation in both groups, and there were no cases of revision surgery. There were no significant differences in the coronal and sagittal tibial component alignment and size between the groups. The JSSF and SAFE-Q improved. There were no significant differences between groups, except for the preoperative JSSF score. ConclusionsDuring the learning curve period, careful surgical indications and surgeries are desired. However, we found that when experienced surgeons participated as assistants, favorable results could be expected even when inexperienced surgeons performed the surgery. Level of evidenceⅢ

Increased Accuracy in Templating for Total Knee Arthroplasty Using 3D Models Generated from Radiographs.

Templating prior to total hip arthroplasty is a widely adopted practice that aims to improve operative efficiency and reduce clinical outliers. Predicting implant size before total knee arthroplasty (TKA), although less common, could increase operating room efficiency by reducing necessary equipment needed for the procedure. This study compared templating accuracy in TKA using two-dimensional (2D) digital radiographs to a novel imaging technology that generates a three-dimensional (3D) model from these 2D radiographs. Two hundred and two robotic-assisted primary TKA surgical cases using Persona Knee System (Zimmer Biomet, Warsaw, IN) were retrospectively analyzed. For all cases, 3D templating was completed preoperatively using a novel radiographic image acquisition protocol. Using the same radiographs, the knee was templated using a 2D digital templating program. All surgeons were blinded to the final implant sizes, and all templating was done independently. The accuracy of predictions within ± 1 from the final implant size was determined for the femoral and tibial components. The accuracy (within 1 size) of tibial size predictions was comparable between attending surgeons and residents (87 vs. 82%, p = 0.08), but attending surgeons more accurately predicted the femoral size (77 vs. 60%, p < 0.05). The 2D to 3D imaging technology more accurately predicted both tibial and femoral sizes compared with the attending surgeons (99.5 vs. 87%, p < 0.05; 84% vs. 77%, p < 0.05). However, the imaging technology, attending surgeons, and residents were all more likely to overestimate femur size (p < 0.05). Moreover, the 3D imaging technology predicted the exact tibial component size in 93.1% of cases, which was significantly greater compared with residents (40%, p < 0.01) and attending surgeons (53%, p < 0.01). The 2D to 3D imaging technology more accurately predicted tibial and femoral component sizes compared with 2D digital templating done by surgeons. All templating predictions were more accurate for the tibial implant size than for the femoral size. The increased accuracy of implant size predictions from this 3D templating technology has the potential to improve intraoperative efficiency and minimize costs and surgical time.

Accuracies of bone resection, implant position, and limb alignment in robotic-arm-assisted total knee arthroplasty: a prospective single-centre study

ObjectiveThis study assessed the accuracy of robotic-arm-assisted total knee arthroplasty (RATKA) for bone resection, component size prediction, implant placement, and limb alignment.MethodsThis prospective cohort study included 36 patients. All procedures were performed by a single experienced surgeon, using an identical approach and implant designs. The MAKO RIO Robotic Interactive Orthopaedic Arm (Stryker, Mahwah, NJ, USA) system was used. The actual bone resection, implant placement, component size, and postoperative mechanical alignment were recorded, then compared with the preoperative plan.ResultsThe mean absolute differences from the plan for the distal (medial and lateral) and posterior (medial and lateral) femoral cuts were 0.39 mm (0.62), 0.49 mm (0.70), 0.62 mm (0.79), and 0.65 mm (0.81), respectively, with 0.57° (0.65) varus. The mean absolute differences in the medial and lateral tibial cuts were 0.56 mm (0.75) and 0.58 mm (0.76), with 0.48° (0.16) varus and 0.54° (0.25) anterior/posterior slope. Of 192 bone resections, 176 (91.7%) were within ≤ 1 mm of the preoperative plan. The accuracies of femoral and tibial component size prediction were 100% and 97.22%, respectively. The mean absolute difference in final limb coronal alignment was 0.92° (0.65). Of the alignments, 18 (75.0%) were within ≤ 1.00° of the plan, and 100% were within ≤ 3.00° of the plan.ConclusionRATKA could accurately predict the component size and execute a preoperative plan to achieve precise bone resection, and implant placement, thereby reducing alignment outliers.

Machine learning algorithms predict within one size of the final implant ultimately used in total knee arthroplasty with good-to-excellent accuracy.

To develop a novel machine learning algorithm capable of predicting TKA implant sizes using a large, multicenter database. A consecutive series of primary TKA patients from two independent large academic and three community medical centers between 2012 and 2020 was identified. The primary outcomes were final tibial and femoral implant sizes obtained from an automated inventory system. Five machine learning algorithms were trained using six routinely collected preoperative features (age, sex, height, weight, and body mass index). Algorithms were validated on an independent set of patients and evaluated through accuracy, mean absolute error (MAE), and root mean-squared error (RMSE). A total of 11,777 patients were included. The support vector machine (SVM) algorithm had the best performance for femoral component size(MAE = 0.73, RMSE = 1.06) with accuracies of 42.2%, 88.3%, and 97.6% for predicting exact size, ± one size, and ± two sizes, respectively. The elastic-net penalized linear regression (ENPLR) algorithm had the best performance for tibial component size (MAE 0.70, RMSE = 1.03) with accuracies of 43.8%, 90.0%, and 97.7% for predicting exact size, ± one size, and ± two sizes, respectively. Machine learning algorithms demonstrated good-to-excellent accuracy for predicting within one size of the final tibial and femoral components used for TKA. Patient height and sex were the most important factors for predicting femoral and tibial component size, respectively. External validation of these algorithms is imperative prior to use in clinical settings. Case-control, III.

Accuracy of Weightbearing CT vs Non-Weightbearing CT Scans for Patient-Specific Instrumentation in Total Ankle Arthroplasty

Category:AnkleIntroduction/Purpose:Total ankle arthroplasty (TAA) is a popular and viable option for end stage ankle arthritis. Accuracy and reproducibility in placing the implant on the mechanical axis has been shown to be paramount in total ankle replacement. Patient specific pre-operative navigation up until this past year has been based off of non-weightbearing computerized tomography (CT). Our institution has created a protocol to use weightbearing CT in the pre-operative patient specific navigation for TAA using the ProphecyTM system. The purpose of our study was to compare the accuracy and reproducibility of implant alignment and size using WBCT versus prior studies using NWBCT for the Prophecy reports.Methods:Patients who underwent TAA using our WBCT protocol for their Prophecy scans had their charts reviewed to see if they met the proper inclusion criteria. Inclusion criteria was a primary TAA with proper follow-up to have first post-operative weightbearing radiographs. The first post-operative weightbearing radiographs were used to measure alignment of the axis of the implant in frontal and sagittal planes comparative to the tibial axis. These results were then compared to the pre-operative prophecy scans to determine reproducibility. The size of the implants components were also recorded for each patient and compared to the pre-operative predicted implant sizes from the patient specific reports. Our results were also compared to previous studies on reproducibility of patient specific navigation when using non-weightbearing CT.Results:Ten patients met our inclusion criteria of WBCT ProphecyTM preoperative planning. 100% of the TAA were within the intended target of less than 50 varus or valgus. The average post-operative coronal alignment was an average of 0.844 degrees. Average sagittal plane deformity was 1.88 degrees post-operative. Tibial component size was properly predicted 100% of the time and talar component in all but one patient.Conclusion:This data supports superior accuracy and reproducibility in pre-operative patient specific navigation when utilizing WBCT for TAA vs published controls with non-weightbearing CT.

Can the tibial length predict the size of tibial component of total knee arthroplasty?

Total knee arthroplasty (TKA) is performed worldwide. TKA is performed to relief pain, correct deformities and improve mobility in patients with debilitating diseases of their knee joints. Templating is done as pre-operative planning for TKA. Certain parameters, such as shoe size, had been studied as predictor (s) for implant size. This study aimed to determine if the tibial length (TL) can also be as a predictor of a tibial component of TKA. TL and tibial plateau width (TPW) measurements were done on dry adult tibiae. Proximal tibiae were traced on tracing paper, to obtain anterior-posterior and lateral tracings. Length of tracings confirmed with measurement on dry bones. A TKA template, converted to 100% scale was used to estimate the tibial baseplate by two orthopaedic surgeons. A total of 51 matured, non-sexed, non-paired tibiae were studied. There was a statistically significant positive relationship between the TL and the TPW (P = 0.0001). Furthermore, a statistically significant positive relationship was also observed between the TL and the tibial implant baseplate (P = 0.0001). The study showed that a particular range of tibia length will accommodate certain sizes of the tibial implant baseplate. The tibia length can be used as a predictor of the size of tibial baseplate of TKA.

Morphometric measurement of the proximal tibia to design the tibial component of total knee arthroplasty for the Thai population

PurposeThis study evaluates the morphology of the Thai proximal tibia based on three-dimensional (3D) models to design the tibial component.MethodsThe 3D models of 480 tibias were created using reverse engineering techniques from computed tomography imaging data obtained from 240 volunteers (120 males, 120 females; range 20–50 years). Based on 3D measurements, a digital ruler was used to measure the distance between the triangular points of the models. The morphometric parameters consisted of mediolateral length (ML), anteroposterior width (AP), medial anteroposterior width (MAP), lateral anteroposterior width (LAP), central to a medial length (CM), central to a lateral length (CL), medial anterior radius (MAR), lateral anterior radius (LAR), and tibial aspect ratio (AR). An independent t-test was performed for gender differences, and K-means clustering was used to find the optimum sizes of the tibial component with a correlation between ML length and AP width in Thai people.ResultsThe average morphometric parameters of Thai proximal tibia, namely ML, AP, MAP, LAP, CM, and CL, were as follows: 72.52 ± 5.94 mm, 46.36 ± 3.84 mm, 49.22 ± 3.62 mm, 43.59 ± 4.05 mm, 14.29 ± 2.72 mm, and 15.28 ± 2.99 mm, respectively. The average of MAR, LAR, and AR was 24.43 ± 2.11 mm, 21.52 ± 2.00 mm, and 1.57 ± 0.08, respectively. All morphometric parameters in males were significantly higher than those of females. There was a difference between the Thai proximal tibia and other nationalities and a mismatch between the size of the commercial tibial component and the Thai knee. Using K-means clustering analysis, the recommended number of ML and AP is seven sizes for the practical design of tibial components to cover the Thai anatomy.ConclusionThe design of the tibial component should be recommended to cover the anatomy of the Thai population. These data provide essential information for the specific design of Thai knee prostheses.

Accuracy of Weightbearing CT Scans for Patient-Specific Instrumentation in Total Ankle Arthroplasty.

Background:Total ankle arthroplasty (TAA) is a popular and viable option for end-stage ankle arthritis. Posttraumatic arthritis is the most common etiology of ankle arthritis, which creates the additional challenge of osseus deformity. Accuracy and reproducibility in placing the implant on the mechanical axis has been shown to be paramount in all joint arthroplasty including total ankle replacement. Patient-specific preoperative navigation is a relatively new technology for TAA, and up until this past year has been based off of nonweightbearing (NWBCT) or simulated weightbearing computed tomography (WBCT). Our institution has created a protocol to use WBCT in the preoperative patient-specific navigation for TAA using the Prophecy system. The purpose of our study was to compare the accuracy and reproducibility of implant alignment and size using WBCT vs prior studies using NWBCT for the Prophecy reports.Methods:All patients from July 2019 through October 2020 who underwent TAA were evaluated. Inclusion criteria consisted of primary TAA using patient-specific preoperative navigation who had postoperative radiographs in the 4-6-week time frame. Prophecy predictions and measurements were then compared to actual implant placement and size.Results:Ten patients met our inclusion criteria of WBCT Prophecy preoperative planning using 2 different implant systems. Preoperative deformities in this cohort were small. The average postoperative coronal alignment was 0.84 degrees, range 0.19 to 2.4 degrees. Average postoperative sagittal plane deformity was 1.9 degrees, range 0.33 to 5.05 degrees. Tibial component size was properly predicted in all patients, talar component in 9 of 10.Conclusion:This initial report supports accuracy and reproducibility in preoperative patient-specific navigation when using WBCT for TAA with these implants. All TAAs were within the intended target of less than 5 degrees varus or valgus.Level of Evidence:Level III, retrospective comparative analysis.

Validation and performance of a machine-learning derived prediction guide for total knee arthroplasty component sizing.

Anticipation of patient-specific component sizes prior to total knee arthroplasty (TKA) is essential to avoid excessive cost associated with additional surgical trays and morbidity associated with imperfect sizing. Current methods of size prediction, including templating, are inconsistent and time-consuming. Machine learning (ML) algorithms may allow for accurate TKA component size prediction with the ability to make predictions in real-time. Consecutive patients receiving primary TKA between 2012 and 2020 from two large tertiary academic and six community hospitals were identified. The primary outcomes were the final femoral and tibial component sizes extracted from automated inventory systems. Five ML algorithms were trained with routinely corrected demographic variables (age, height, weight, body mass index, and sex) using 80% of the study population and internally validated on an independent set of the remaining 20% of patients. Algorithm performance was evaluated through accuracy, mean absolute error (MAE), and root mean-squared error (RMSE). A total of 17,283 patients that received one of 9 TKA implants from independent manufacturers were included. The SGB model accuracy for predicting ± 4-mm of the true femoral anteroposterior diameter was 83.6% and for ± 1 size of the true femoral component size was 95.0%. The SGB model accuracy for predicting ± 4-mm of the true tibial medial/lateral diameter was 83.0% and for ± 1 size of the true tibial component size was 97.8%. Patient sex was the most influential feature in terms of informing the SGB model predictions for both femoral and tibial component sizing. A TKA implant sizing application was subsequently created. Novel machine learning algorithms demonstrated good to excellent performance for predicting TKA component size. Patient sex appears to contribute an important role in predicting TKA size. A web-based real-time prediction application was created capable of integrating patient specific data to predict TKA size, which will require external validation prior to clinical use.

Tibial component coverage affects tibial bone resorption and patient-reported outcome measures for patients following total knee arthroplasty

PurposeThe aim of this study is to investigate the prognostic value of tibial component coverage (over-hang and under-hang) and the alignment of total knee arthroplasty (TKA) components 1 week after surgery. We select patient-reported outcome measures (PROMS) (the Knee Society score (KSS score) and the Western Ontario and McMaster Universities Osteoarthritis Index-pain score (WOMAC pain score)) and tibial bone resorption (TBR) 2 years after surgery as the end points.MethodsThe study retrospectively analyzed 109 patients undergoing TKA (fixed-bearing prosthesis with asymmetrical tibial tray) from January 2014 to December 2017 in Huashan Hospital. By using standard long-leg X-rays, anteroposterior (AP) and lateral X-rays of the knee, tibial component coverage (under-hang or over-hang), AP tibial-femoral anatomical angle (AP-TFA), AP femoral angle (AP-FA), AP tibial angle (AP-TA), and lateral tibial angle (L-TA) were measured at 1 week after surgery, while TBR was measured through postoperative 1-week and 2-year AP and lateral radiographs of the knee on three sides (medial side, lateral side on AP radiograph, and anterior side on lateral radiograph). The Pearson correlation analysis, simple linear regression, multiple linear regression, the Student’s t test, and one-way ANOVA together with Tukey’s post hoc test (or Games-Howell post hoc test) were used in the analyses.ResultsTibial under-hang was more likely to appear in our patients following TKA (42%, medially, 39%, laterally, and 25%, anteriorly). In multivariate linear regression analysis of TBR, tibial under-hang (negative value) 1 week after surgery was positively correlated with TBR 2 years later on the medial (p = 0.003) and lateral (p = 0.026) side. Tibial over-hang (positive value) 1 week after surgery on the medial side was found negatively related with KSS score (p = 0.004) and positively related with WOMAC pain score (p = 0.036) 2 years later in multivariate linear regression analysis of PROMS. Both scores were better in the anatomically sized group than in the mild over-hang group (or severe over-hang) (p < 0.001). However, no significant relationship was found between the alignment of TKA components at 1 week after surgery and the end points (TBR and PROMS) 2 years later.ConclusionUnder-hang of the tibial component on both the medial and lateral sides can increase the risk of TBR 2 years later. Over-hang of tibial component on the medial side decreases the PROMS (KSS score and WOMAC pain score) 2 years later. An appropriate size of tibial component during TKA is extremely important for patient’s prognosis, while the alignment of components might not be as important.

Component asymmetry in bilateral total knee arthroplasty in the middle eastern population

PurposeProper sizing of the femoral and tibial components is an important step in total knee replacement (TKA). When performing bilateral TKA, there is often an opinion that the same size prosthesis as the opposite side will suffice, even though there are reports of anatomical differences between sides. In this study, we quantify the incidence of asymmetry in femoral and tibial component sizes in staged bilateral TKA in a Middle East population. MethodsThis is a retrospective observational study of all patients who underwent uncomplicated bilateral TKA with the same type of prosthesis by two surgeons at the same institute, between January 2013 and January 2019. ResultsThere were 123 patients, femoral and tibial component size variationswerepresent in 42patients (34.1%) and 30 patients (24.4%) respectively. The variation was evident in both posterior substituting (PS) and cruciate retaining (CR) designs. The femoral components had a higher variation in size between the sides for both PS and CR designs than the tibial components for both designs. The percentage variation in the size of the femoral component was similar for PS and CR subgroups (32.7% and 33.3% respectively). However, for the tibial component, the size variation was higher for PS design (24.5%) than for CRdesign (18.7%). 7.3% had a side-to-side variation by 2 or more sizes in both femoral and tibial components. ConclusionVariations in the size of the femoral and tibial components is common in patients undergoing bilateral TKA. Contralateral component size should not be used as the determinant of component sizes on the other side.

Demographic data is more predictive of component size than digital radiographic templating in total knee arthroplasty

BackgroundPreoperative radiographic templating for total knee arthroplasty (TKA) has been shown to be inaccurate. Patient demographic data, such as gender, height, weight, age, and race, may be more predictive of implanted component size in TKA.Materials and methodsA multivariate linear regression model was designed to predict implanted femoral and tibial component size using demographic data along a consecutive series of 201 patients undergoing index TKA. Traditional, two-dimensional, radiographic templating was compared to demographic-based regression predictions on a prospective 181 consecutive patients undergoing index TKA in their ability to accurately predict intraoperative implanted sizes. Surgeons were blinded of any predictions.ResultsPatient gender, height, weight, age, and ethnicity/race were predictive of implanted TKA component size. The regression model more accurately predicted implanted component size compared to radiographically templated sizes for both the femoral (P = 0.04) and tibial (P < 0.01) components. The regression model exactly predicted femoral and tibial component sizes in 43.7 and 43.7% of cases, was within one size 90.1 and 95.6% of the time, and was within two sizes in every case. Radiographic templating exactly predicted 35.4 and 36.5% of cases, was within one size 86.2 and 85.1% of the time, and varied up to four sizes for both the femoral and tibial components. The regression model averaged within 0.66 and 0.61 sizes, versus 0.81 and 0.81 sizes for radiographic templating for femoral and tibial components.ConclusionsA demographic-based regression model was created based on patient-specific demographic data to predict femoral and tibial TKA component sizes. In a prospective patient series, the regression model more accurately and precisely predicted implanted component sizes compared to radiographic templating.Level of evidenceProspective cohort, level II.