Effect of training level on accuracy of digital templating in primary total hip and knee arthroplasty

The accuracy of preoperative implant size prediction achieved by digital templating in total knee arthroplasty is not affected by the quality of lateral knee radiographs

Background

Digital templating software can be used for preoperative implant size prediction in total knee arthroplasty (TKA). However, the accuracy of its prediction is reported to be low, and the impact of radiograph quality is unclear.

Purpose

To investigate on the application of lateral knee radiograph quality criteria for knee rotation (KR) and knee abduction/adduction (KA) and their impact on the accuracy of final implant size prediction achieved by preoperative digital templating for TKA.

Methods

A total of 191 radiographs of patients undergoing TKA were allocated into four groups according to their KR as measured at the posterior femoral condyles and their KA as measured at the distal femoral condyles on lateral knee radiographs: group A (KR ≤ 5 mm, KA ≤ 5 mm), B1 (KR > 5 mm, KA ≤ 5 mm), B2 (KR ≤ 5 mm, KA > 5 mm) and B3 (KR > 5 mm, KA > 5 mm). Preoperative templating of femoral and tibial implant size using digital templating software was carried out by two observers. Correlation coefficients (CCs) between planned and final implant size, percentage of cases with planned to final size match as well as percentage of cases within ±1 and ±2 of planned to final size were reported according to groups.

Results

Group A showed the highest percentage of cases with matching planned to final femoral implant size (45%) and the highest percentage of cases with ±1 planned to final implant size (86%) as compared to B1 (match 28%, ±1 84%), B2 (match 41%, ±1 84%) and B3 (match 35%, ±1 78%). CCs for planned to final implant size were reported at >0.75 in all groups. No statistically significant difference in the CCs of planned to final implant size amongst groups was found.

Conclusion

The accuracy of implant size prediction achieved by preoperative digital templating for TKA is neither affected by KR nor KA on lateral knee radiographs.

Level of evidence

Level III.

Surgeon's Experience and Accuracy of Preoperative Digital Templating in Primary Total Hip Arthroplasty

Purpose

Preoperative planning has become essential in performance of total hip arthroplasty (THA). However, data regarding the effect of the planner's experience on the accuracy of digital preoperative planning is limited. The objective of this study was to assess the accuracy of digital templating in THA based on the surgeon's experience.

Materials and Methods

A retrospective study was conducted. An analysis of 98 anteroposterior pelvic radiographs, which were individually templated by four surgeons (two hip surgeons and two orthopaedic residents) using TraumaCad® digital planning, was performed. A comparison of preoperatively planned sizes with implanted sizes was performed to evaluate the accuracy of predicting component size. The results of preoperative planning performed by hip surgeons and orthopaedic residents were compared for testing of the planner's experience.

Results

Femoral stem was precisely predicted in 32.4% of cases, acetabular component in 40.3%, and femoral offset in 76.7%. Prediction of cup size showed greater accuracy than femoral size among all observers. No differences in any variable were observed among the four groups (acetabular cup P=0.07, femoral stem P=0.82, femoral offset P=0.06). All measurements showed good reliability (intraclass correlation coefficient [ICC] acetabular cup: 0.76, ICC femoral stem: 0.79).

Conclusion

The results of this study might suggest that even though a surgeon's experience supports improved precision during the planning stage, it should not be restricted only to surgeons with a high level of experience. We consider preoperative planning an essential part of the surgery, which should be included in training for orthopaedics residents.

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

Background

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).

Methods

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.

Results

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).

Conclusions

The study findings show that RA-TKA does not take additional time than C-TKA.

Do the sizes of total hip arthroplasty implants match between 3D planning software and 2D templating?

INTRODUCTION

The use of three-dimensional (3D) planning before a total hip arthroplasty (THA) procedure is becoming increasingly popular as it offers several theoretical benefits: better restoration of a patient's anatomy, fewer intraoperative problems, and lower THA cost. It is said to be more accurate than two-dimensional (2D) planning, but as far as we know, no study has investigated how well the implant sizes match between 3D and 2D planning for a surgeon who is just starting to use 3D planning. Consistent implant sizes would make it easier for a surgeon to transition from one system to another. This led us to conduct a retrospective comparative study to: (1) compare how well the implant sizes match between a 3D planning system and a 2D planning method (conventional radiography using templates); (2) determine if the sizes planned on the 3D system match the implants that were used in the patient; (3) determine if the sizes planned with the 2D method match the implants that were used in the patient.

HYPOTHESIS

There is a good match in the implant sizes between the 3D and 2D planning.

METHODS

A retrospective observational, single-surgeon study was done with patients who underwent THA between January 2019 and September 2021 at a single teaching hospital. For each patient, the size of the THA implants was planned preoperatively in 3D using proprietary software (Optimized Positioning System™, Corin) and 2D templating. These patients were the first to be operated on by this surgeon based on 3D planning.

RESULTS

Forty-nine patients were included. The implant size matched exactly between the two planning methods for 20% (10/49) of cups [one size larger with 3D in 35% of hips (17/49) and two sizes larger in 20% of hips (10/49)], for 53% (26/49) of femoral stems [one size smaller with 3D in 53% of hips (26/49)] and for 14% (7/49) of complete THA implant systems (cup, femoral stem, femoral head). The size planned in 3D was the same as the cup size implanted in 51% (25/49) of hips, as the femoral stem size in 65% (32/49) and as the complete THA system in 22% (11/49). The cup was within one size in 88% (43/49) of hips and the femoral stem was within one size in 98% (48/49) of hips. The size planned in 2D was the same as the cup size implanted in 45% (22/49) of hips, as the femoral stem size in 63% (32/49) and as the complete THA system in 18% (9/49). The cup was within one size in 86% (42/49) of hips and the femoral stem was within one size in 96% (47/49) of hips with 2D templating. There was no statistically significant difference in the size matching between the 2D and 3D techniques for either the implanted cup (p=0.5) or the implanted femoral stem (p=0.8).

CONCLUSION

There is a poor match between the implant sizes determined by 3D and 2D planning. Based on our findings, the shift from 2D templating to 3D planning must be done gradually given the learning curve associated with 3D systems.

LEVEL OF EVIDENCE

III; comparative retrospective study.

Technical note for intraoperative determination of proper acetabular cup size in primary total hip arthroplasty

BACKGROUND

Selecting the optimal size of components is crucial when performing a primary total hip arthroplasty. Implanting the accurate size of the acetabular component can occasionally be exacting, chiefly for surgeons with little experience, whilst the complications of imprecise acetabular sizing or over-reaming can be potentially devastating.

AIM

To assist clinicians intraoperatively with a simple and repeatable tip in elucidating the ambivalence when determining the proper acetabular component size is not straightforwardly achieved, specifically when surgeons are inexperienced or preoperative templating is unavailable.

METHODS

This method was employed in 263 operations in our department from June 2021 to December 2022. All operations were performed by the same team of joint reconstruction surgeons, employing a typical posterior hip approach technique. The types of acetabular shells implanted were: The Dynasty® acetabular cup system (MicroPort Orthopedics, Shanghai, China) and the R3® acetabular system (Smith & Nephew, Watford, United Kingdom), which both feature cementless press-fit design.

RESULTS

The mean value of all cases was calculated and collated with each other. We distinguished as oversized an implanted acetabular shell when its size was > 2 mm larger than the size of the acetabular size indicator reamer (ASIR) or when the implanted shell was larger than 4 mm compared to the preoperative planned cup. The median size of the implanted acetabular shell was 52 (48-54) mm, while the median size of the preoperatively planned cup was 50 (48-56) mm, and the median size of the ASIR was 52 (50-54) mm. The correlation coefficient between ASIR size and implanted acetabular component size exhibited a high positive correlation with r = 0.719 (P < 0.001). Contrariwise, intraoperative ASIR measurements precisely predicted the implanted cups' size or differed by only one size (2 mm) in 245 cases.

CONCLUSION

In our study, we demonstrated that the size of the first acetabular reamer not entering freely in the acetabular rim corroborates the final acetabular component size to implant. This was also corresponding in the majority of the cases with conventional preoperative templating. It can be featured as a valid tool for avoiding the potentially pernicious complications of acetabular cup over-reaming and over-sizing in primary total hip arthroplasty. It is a simple and reproducible technical note useful for confirming the predicted acetabular cup size preoperatively; thus, its application could be considered routinely, even in cases where preoperative templating is unavailable.

The accuracy of digital templating in the preoperative planning of total knee arthroplasties: A systematic review and meta-analysis

AIMS

Accurately predicting the implant size in total knee arthroplasties could increase the efficiency of the operation, decrease the costs associated with the procedure and result in improved patient outcomes. To substantiate its continued use, digital templating must demonstrate itself to be an accurate tool in predicting component size in order for surgeons to confidently use it to optimize the procedure.

METHODS

A systematic literature review was performed and identified 16 studies within the Pubmed, Ebsco and Ovid-Embase databases, with 1189 TKR prostheses included for analysis. A quality of evidence assessment was performed on each study depending on the study design. A random effects meta-analysis model was used to pool overall implant accuracy and the reported inter-rater agreement when performing digital templating and displayed in a forest plot. Meta-regression was used analyze potential factors that may affect the accuracy of digital templating.

RESULTS

The pooled proportion of accurate templates with 0 margin of error was found to be 56% (52-61, 95CI), which increases to 96% (0.94-0.98, 95CI) when allowing for a 1 size margin of error. Subgroup analysis between femoral and tibial components concluded no statistically significant difference.

CONCLUSIONS

This study supports the continued use of digital templating for planning total knee arthroplasties and recommends further subgroup analysis of patient age, body mass index and sex against accuracy. This review was registered in the International Prospective Register of Systematic Reviews Database under ID: CRD420222367461. No funding was provided for the completion of this systematic review.

BACKGROUND

Templating in the preoperative planning of total knee arthroplasties is a vital step in ensuring maximum operative efficiency. A method that can accurately predict the required implant size within 1 size could improve theatre turnover, decrease costs and benefit patient outcomes. The current literature on the accuracy of digital templating in total knee arthroplasties lacks a systematic review calculating the overall accuracy of the process, this study aims to address this gap.

Analyzing the Accuracy of Digital Sizing on Long-Leg Alignment X-rays by Using a 1-Inch Ball Bearing: A Cheap and Effective Method

Background and objective Sizing on digital films is important for implants and planning deformity correction. CT is the most accurate digital measurement method. We use a 1-inch ball bearing (cost: $1) to size our long-leg standing films (LLSFs) when planning deformity correction. In this study, we aimed to assess the accuracy of digital measurements calibrated by this method. Methods We conducted An IRB-approved study involving 25 patients having both an LLSF with a 1-inch ball bearing taped to the inner mid-thigh and a CT scanogram. The longest distance in the axial cut of the bilateral ankle, knee, and femoral heads of the CT images were compared to the same anatomic locations on LLSFs calibrated with the ball bearing using the online digital planning software DetroitBonesetter (DBS) and measurements from our Picture Archiving Communication Software (PACS). Five observers performed each measurement. Results The average measurement differences between the gold standard CT scan and LLSFs calibrated with DBS were as follows: 0.110 ± 0.432 mm (femoral head); 2.173 ± 0.0619 mm (knee); and 3.671 ± 0.30 mm (ankle). In PACS, they were as follows: 5.470 ± 0.381 mm (femoral head); 6.248 ± 0.712 mm (knee); and 1.806 ± 0.548 mm (ankle). The intraclass correlation coefficient for 600 measurements by five observers was 0.972. Conclusions The $1 ball-bearing sizing on DBS using LLSFs provides accuracy to <1 mm for the femoral head, 2 mm at the knee, and 3.7 mm at the ankle. It was significantly better than the PACS system for both the femoral head and knee (<0.001), while PACS was better at the ankle (<0.001).

Predictability of implant sizes during cruciate-retaining total knee arthroplasty using an image-free hand-held robotic system

The use of appropriately sized implants is critical for achieving optimal gap balance following total knee arthroplasty (TKA). Inappropriately sized implants could result in several complications. Robot-assisted TKA (RA-TKA) using CT-based pre-operative planning predicts implant sizes with high accuracy. There is scant literature describing the accuracy of image-free RA-TKA in predicting implant sizes. The purpose of this study was to assess the accuracy of an image-free robotic system in predicting implant sizes during RA-TKA. Patients who underwent cruciate-retaining RA-TKA for primary osteoarthritis, using an image-free hand-held robotic system were studied. The predicted and implanted sizes of the femoral component, tibial component and polyethylene insert, for 165 patients, were recorded. Agreement between robot-predicted and implanted component sizes was assessed in percentages, while reliability was assessed using Cohen's weighted kappa coefficient. The accuracy of the robotic system was 63% (weighted-kappa = 0.623, P < 0.001), 94% (weighted-kappa = 0.911, P < 0.001) and 99.4% (weighted-kappa = 0.995, P < 0.001), in predicting exact, ± 1 and ± 2 sizes of the femoral component, respectively. For the tibial component, an accuracy of 15.8% (weighted-kappa = 0.207, P < 0.001), 55.8% (weighted-kappa = 0.378, P < 0.001) and 76.4% (weighted-kappa = 0.568, P < 0.001) was noted, for predicting exact, ± 1 and ± 2 sizes respectively. An accuracy of 88.5%, 98.2% and 100%, was noted for predicting exact, ± 1 and ± 2 sizes of the polyethylene insert respectively. Errors in predicting accurate implant sizes could be multi-factorial. Though the accuracy of image-free RA-TKA with respect to alignment and component positioning is established, the surgeon's expertise should be relied upon while deciding appropriate implant sizes.

Enhancing Precision and Efficiency in Knee Arthroplasty: A Comparative Analysis of Computer-Assisted Measurements with a Novel Software Tool versus Manual Measurements for Lower Leg Geometry

(1) Background: The aim of this prospective study was to evaluate measurement software in comparison with manual measurements using inter-observer and intra-observer variability on radiographs in the preoperative planning of total knee arthroplasty. (2) Methods: Two independent observers retrospectively measured the mechanical lateral proximal femoral angle (mLPFA), the mechanical lateral distal femoral angle (mLDFA), the joint line convergence angle (JLCA), the mechanical medial proximal tibial angle (mMPTA), the mechanical lateral distal tibial angle (mLDTA), the hip-knee angle or mechanical tibial-femoral axis angle (HKA), and the anatomical-mechanical angle (AMA) on 55 long-leg anteroposterior radiographs manually twice, followed by measurements using dedicated software. Variability between manual and computer-aided planning was assessed, and all measurements were performed a second time after 14 days in order to assess intra-observer variability. (3) Results: Concerning intra-observer variability, no statistically significant difference was observed regarding the software-based measurements. However, significant differences were noted concerning intra-observer variability when measuring the mLDFA and AMA manually. Testing for statistical significance regarding variability between manual and software-based measurements showed that the values varied strongly between manual and computer-aided measurements. Statistically significant differences were detected for mLPFA, mLDFA, mMPTA, and mLPTA on day 1, and mLPFA, mMPTA, and mLPTA on day 15, respectively. (4) Conclusions: Preoperative planning of leg axis angles and alignment using planning software showed less inter- and intra-observer variability in contrast to manual measurements, and results differed with respect to manual planning. We believe that the planning software is more reliable and faster, and we would recommend its use in clinical settings.

A Video Teaching Tool Is Effective for Training Residents in Hip Arthroplasty Templating

Work hour restrictions imposed on orthopedic surgery residents since the early 2000s have reduced educational opportunities at the workplace and encouraged alternative strategies for teaching outside the clinical setting. Preoperative templating is essential for safe and effective total hip arthroplasty (THA) and is accurate in predicting final implants. We sought to determine the effectiveness of a video tool for teaching orthopedic residents basic THA templating skills. We developed a video-based teaching tool with instructions on proper THA templating techniques. Ten cases were selected for testing, after excluding patients with severe hip deformities and poor-quality radiographs and only retaining those with concordance between templating by the senior authors and implanted components. The study subjects included three postgraduate year 1 (PGY-1), three PGY-2, and three PGY-5 residents, and three adult reconstruction fellows (PGY-6). Templating skills were assessed before and after watching the instructional video. The evaluation included the size and positioning of femoral and acetabular components, as well as the restoration of leg length. Each templating session was repeated twice. Variance was measured to evaluate consistency in measurements. A linear mixed model and F-test were used for statistical analyses. The number of years in training significantly affected performance prior to exposure to the instructional video. Post-exposure, there was a significant improvement in the accuracy of sizing and positioning of acetabular and femoral components for PGY-1, PGY-2, and PGY-5 residents. The results achieved were comparable to PGY-6 examiners, who did not gain substantial performance benefits from the instructional video. Limb length restoration was less affected by experience or exposure to the video. Component positioning and sizing, as well as leg length discrepancy (LLD), showed a significant decrease in variance after the intervention in all study groups. Video learning is reliable in teaching invaluable skills to orthopedic surgery residents without encroaching on work hours. We conceived a concise video to train orthopedic residents to perform THA templating with proper technique and demonstrated its efficiency and reproducibility.

Accuracy of Total Hip Arthroplasty Templating Using Set Calibration Magnifications

Background Templating for total hip arthroplasty has been adopted over recent decades as a reliable and accurate method for pre-operative planning. The use of calibration markers for this process provides a recognised benefit at the expense of cost, availability and error. Many surgeons use a set magnification of 118% to account for calibration errors when templating total hip arthroplasty. This study aims to assess the accuracy of templating with standardised magnifications and assess the effect of BMI on templating accuracy. Materials and methods A retrospective analysis was performed using a single-surgeon series of 119 consecutive total hip arthroplasties. Anteroposterior radiographs were taken pre- or post-operatively without calibration hardware. Pre-operatively, the total hip arthroplasty was templated on TraumaCad (BrainLab Inc, Westchester, IL) using either 118% or 119% calibration magnification. Post-operative magnification was calibrated using the known femoral head diameter. Templated and implanted prostheses were compared for size. Results At 118%, 61.1% of cups matched those templated with 96.3% of cups within two sizes. At 119%, 52.5% of cups used matched their templates with 100% within two sizes. There was no significant difference between 118% and 119% cup size prediction (p=0.49). A trend was noticed in increasing magnification error with increasing BMI. However, BMI had no significant effect on the accuracy of templating cup size within two cup sizes (p=0.58). Conclusion. Templating acetabular cups using a set magnification of 118% or 119% yields accurate results and provides a reliable method to template without calibration equipment. Whilst BMI can affect magnification error, this has no significant effect on the accuracy of implanted cups and stems within two sizes.

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

Background

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.

Materials and methods

Prospectively collected data in a single center from 30 RA-TKAs was 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.

Results

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).

Conclusion

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.

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

PURPOSE

To develop a novel machine learning algorithm capable of predicting TKA implant sizes using a large, multicenter database.

METHODS

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).

RESULTS

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.

CONCLUSION

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.

LEVEL OF EVIDENCE

Case-control, III.

The accuracy and reliability of preoperative digital 2D templating in prosthesis size prediction in uncemented versus cemented total hip arthroplasty: a systematic review and meta-analysis

The purpose of this study was to compare the accuracy and the inter- and intra-observer reliability of preoperative digital 2D templating in prosthesis size prediction for the planning of cemented or uncemented THA.

This study was registered in the NIHR PROSPERO database (ID: CRD42020216649) and conducted according to the PRISMA guidelines. A search of electronic databases in March 2021 found 29 papers overall. The quality of evidence was assessed using the IHE Quality Appraisal of Case Series Studies Checklist and the CASP Randomised Controlled Trials Checklist. A meta-analysis was conducted, and the accuracy was presented as proportions and the inter- and intra-observer reliability were measured using intraclass correlation coefficients (ICC).

Accuracy within one prosthesis size (±1) for cemented stems was 0.89 (95% confidence interval (CI) 0.83–0.95), cemented cups 0.78 (95% CI 0.67–0.89), uncemented stems 0.74 (95% CI 0.66–0.82) and uncemented cups 0.73 (95% CI 0.67–0.79) (test of group differences: p = 0.010). Inter-observer reliability (ICC) for uncemented cups was 0.88 (95% CI 0.85–0.91), uncemented stems 0.86 (95% CI 0.81–0.91), cemented stems 0.69 (95% CI 0.54–0.84) and cemented cups 0.68 (95% CI 0.55–0.81) (test of group differences: p = 0.004). Due to lack of data, intra-observer reliability (ICC) could only be calculated for uncemented prostheses, which for the stems was 0.90 (95% CI 0.88–0.92) and for the cups was 0.87 (95% CI 0.83–0.90) (test of group differences: p = 0.124).

The accuracy of preoperative digital templating is greater for cemented prostheses, but the inter-observer reliability is greater for uncemented prostheses. The intra-observer reliability showed a high level of agreement for uncemented prostheses.

Cite this article: EFORT Open Rev 2021;6:1020-1039. DOI: 10.1302/2058-5241.6.210048

Handheld computer-navigated constrained total knee arthroplasty for complex extra-articular deformities

INTRODUCTION

The present study aimed to assess the postoperative alignment and clinical outcomes of patients with complex extra-articular deformities (EADs) undergoing computer-assisted surgery (CAS) for constrained total knee arthroplasty (TKA) with modular stem extensions.

MATERIALS AND METHODS

From May 2015 to July 2018, ten patients with EADs scheduled for constrained TKA were enrolled retrospectively. The preoperative average deviation from neutral (= 180°) mechanical axis was 15.3° (range of coronal alignment: 150.9° varus-202.9° valgus). Alignment was assessed using an accelerometer-based handheld CAS system. On long-leg films, the positions of the components and possible stems were analysed and templated preoperatively. The average follow-up was 3.3 years (range: 2.0-4.6 years).

RESULTS

The postoperative mechanical axis was within ± 3.0° from neutral in nine patients. In all patients, the Knee Society score (KSS) and range of motion improved significantly. A constrained condylar and a rotating hinge prosthesis were used in five patients each. In eight patients, the 100-mm cementless stem that was preferred by the authors was found to be unusable for the femur or the tibia in the planning stage. For the femur, a cementless 100-mm stem was used in three, and a cemented 30-mm stem in five patients; a femoral stem was not usable in two patients. For the tibia, a cementless 100-mm stem was used in six, and a cemented 30-mm stem in two patients; a monoblock rotating hinge tibia was used in two patients.

CONCLUSIONS

Complex EADs were excellently managed during constrained TKA implantation using the handheld CAS system. Templating allowed the possible stem lengths to be identified and prevented anatomical conflict with the CAS-configured mechanical alignment. Limb alignment and function improved significantly after surgery. No intra- or postoperative complications occurred.

LEVEL OF EVIDENCE

Level IV, retrospective study.

Reproducibility of an Intraoperative Pressure Sensor in Total Knee Replacement

Appropriate soft tissue tension in total knee replacement (TKR) is an important factor for a successful outcome. The purpose of our study was to assess both the reproducibility of a modern intraoperative pressure sensor (IOP) and if a surgeon could unconsciously influence measurement. A consecutive series of 80 TKRs were assessed with an IOP between January 2018 and December 2020. In the first scenario, two blinded sequential measurements in 48 patients were taken; in a second scenario, an initial blinded measurement and a subsequent unblinded measurement in 32 patients were taken while looking at the sensor monitor screen. Reproducibility was assessed by intraclass correlation coefficients (ICCs). In the first scenario, the ICC ranged from 0.83 to 0.90, and in the second scenario it ranged from 0.80 to 0.90. All ICCs were 0.80 or higher, indicating reproducibility using a IOP and that a surgeon may not unconsciously influence the measurement. The use of a modern IOP to measure soft tissue tension in TKRs is a reproducible technique. A surgeon observing the measurements while performing IOP may not significantly influence the result. An IOP gives additional information that the surgeon can use to optimize outcomes in TKR.

Robotic arm-assisted total knee arthroplasty improves preoperative planning and intraoperative decision-making

Background

The reliability of robotic arm-assisted total knee arthroplasty (RA-TKA) has been previously reported. In this study, we evaluated the predictive accuracy of the RA-TKA system in determining the required bone resection and implant size preoperatively and its effect on intraoperative decision-making.

Methods

Data on the outcomes of RA-TKA procedures performed in our department were prospectively collected. A three-dimensional model of the femur, tibia, and fibula was reconstructed using standard computed tomography (CT) images. The model was used preoperatively to predict bone required resection for the femur and tibia and implant size. Intraoperatively, the images were registered to the local anatomy to create a patient-specific model for decision-making, including real-time measurement of the medial-to-lateral difference in the extension/flexion gap and TKA component alignment. Differences between predicted and real bone resections and implant size were evaluated, and the post-TKA mechanical axis of the lower limb and difference in medial-to-lateral flexion/extension gap were measured.

Results

The analysis was based on the data of 28 patients who underwent TKA to treat severe osteoarthritis. The RA-TKA system successfully predicted the femoral and tibial component within one implant size in 28/28 cases (100%). For the 168 bone resections performed, including both femoral and tibial cuts, the resection was within 1 mm of the predicted value in 120/168 (71%) of the cuts. The actual versus predicted bone resection was statistically different only for the lateral tibial plateau (p = 0.018). The medial-to-lateral gap difference was between − 1 and 1 mm, except in one case. The achieved lower limb alignment was accurate overall, with the alignment being within < 1.0° of the neutral mechanical axis in 13/28 cases (46%) and within < 3.0° in 28/28 cases (100%).

Conclusions

The RA-TKA system provided considerable pre- and intraoperative surgical assistance to achieve accurate bone resection, appropriate component sizing, and postoperative alignment after RA-TKA.

Accuracy of one-dimensional templating on linear EOS radiography allows template-directed instrumentation in total knee arthroplasty

BACKGROUND

Templating for total knee arthroplasty (TKA) is routinely performed on two-dimensional standard X-ray images and allows template-directed instrumentation. To date, there is no report on one-dimensional (1D) anteroposterior (AP) templating not requiring specific templating software. We aim to describe a novel technique and explore its reliability, accuracy and potential cost-savings.

METHODS

We investigated a consecutive series of TKAs at one institution between January and July 2019. Patients with preoperative low-dose linear AP EOS radiography images were included. Implant component sizes were retrospectively templated on the AP view with the hospitals imaging viewing software by two observers who were blinded to the definitive implant size. Planning accuracy as well as inter- and intra-observer reliability was calculated. Cost-savings were estimated based on the reduction of trays indicated by the 1D templating size estimations.

RESULTS

A total of 141 consecutive TKAs in 113 patients were included. Accuracy of 1D templating was as follows: exact match in 53% femoral and 63% tibial components, within one size in 96% femoral and 98% tibial components. Overall 58% of TKA components were planned correctly and 97% within one size. Inter- and intra-rater reliability was good (κ = 0.66) and very good (κ = 0.82), respectively. This templating process can reduce instrumentation from six to three trays per case and therefore halve sterilisation costs.

CONCLUSIONS

The new 1D templating method using EOS AP imaging predicts component sizes in TKA within one size 97% of the time and can halve the number of instrumentation trays and sterilisation costs.

Agreement in component size between preoperative measurement, navigation and final implant in total knee replacement

Background

One of the possible causes of dissatisfaction reported by many patients after total knee replacement (TKR) is the lack of agreement between component size and bone structure. To avoid this complication and facilitate the procedure, preoperative planning with digitized templates is recommended. Surgical navigation indicates the best position and the most adequate size of arthroplasty and may therefore replace preoperative radiographic measurement. The objective of the study was to check agreement between the sizes of TKR components measured before surgery with digitized templates, the size recommended by the navigation and sizes actually implanted.

Methods

In 103 patients scheduled for TKR, preoperative full-limb radiography was performed to measure the mechanical and anatomical axes of the limb, femur and tibia. The most adequate size of the femoral and tibial components was planned by superimposing digitized templates. The size recommended in navigation and the size of the finally implanted components were also recorded.

Results

A high level of agreement was found between the sizes of femoral and tibial components measured by X-rays and in navigation (0.750 and 0.772, respectively) (intraclass correlation and Cronbach's alpha). Agreement between the sizes recommended by X-rays and navigation and those finally implanted was 0.886 for the femur and 0.891 for the tibia. Agreement levels were not different in cases with prior deformities of limb axis.

Conclusions

The high level of agreement found in component sizes between radiographic measurement with digitized templates and navigation suggests that preoperative X-ray measurement is not needed when navigation is used for placement of implants during TKR.

The translational potential of this article

Computer-assisted surgery may avoid preoperative measurement with templates in TKR.

Digital templating of rotating hinge revision and primary total knee arthroplasty

Preoperative digital templating in total knee arthroplastiy (TKA) is useful in predicting implant size, the level of bone resections and the need for special implants. This study should evaluate the templating of a rotating hinge prosthesis and the realization of the preoperative plan. Two observers with different experience levels templated 40 cases which received TKA and R-TKA using digital planning on standard preoperative x-rays. The examiners templated all cases independently and were blinded to the component sizes used intraoperatively. The kappa coefficient and Pearson coefficient were determined. The accuracy in predicting the correct implant size in revision TKA varied from 67,9% to 82,1% depending on the training level of the observer. The two observers show moderate and substantial correlation. The coefficient indicates a substantial agreement in between the two observers in templating revision TKA. The accuracy depends on the experience of the observer. In the cases were the templating was incorrect, the prosthesis was implanted smaller than the preoperative plan. With this knowledge very good results can be made with this prosthesis.

Interobserver and Intraobserver Reliability of Computed Tomography-Based Three-Dimensional Preoperative Planning for Primary Total Knee Arthroplasty

BACKGROUND

Preoperative planning is an important factor for total knee arthroplasty (TKA). The aim of this study is to document the interobserver and intraobserver reliability of computed tomography (CT)-based 3-dimensional (3D) preoperative planning for primary TKA.

METHODS

Twenty knees (10 with osteoarthritis and 10 with rheumatoid arthritis) were studied independently by 6 orthopedic surgeons using a CT-based 3D planning system. The measurements were made twice at more than 3-week intervals without any knowledge of their own previous measurements or those of the others. We assessed the femoral and tibial component sizes and the alignment of the femoral component.

RESULTS

The interobserver and intraobserver agreements for femoral component size were 44.3% and 62.5% with exact size, and increased to 90.7% and 99.2% within one size difference; the intraclass correlation coefficients (ICCs) were 0.919 and 0.936, respectively. The interobserver and intraobserver agreements for tibial component size were 57.0% and 66.7% with exact size, and increased to 87.3% and 90.0% within one size difference; the ICCs were 0.909 and 0.924, respectively. The ICCs for femoral and tibial size were better in rheumatoid arthritis than in osteoarthritis. Interobserver ICC for femoral valgus angle was 0.807, and 0.893 for intraobserver reliability. Interobserver ICC of the femoral external rotation angle was 0.463, and 0.622 for intraobserver reliability.

CONCLUSION

CT-based 3D preoperative planning for primary TKA has clinical implications for predicting appropriate size and alignment of the component in patients with osteoarthritis and rheumatoid arthritis.

Accuracy of digital radiography: regional scaling factors for trauma

BACKGROUND

Surgical planning in trauma is essential for optimal patient care and best patient outcomes. Digital radiography has improved the availability, convenience and access to radiographs worldwide as used in every trauma centre in Australia. One shortcoming, however, is the variability in magnification error associated with different anatomic regions. Accurate assessment of radiographs is paramount to proper surgical planning.

METHODS

A retrospective review of 513 post-operative trauma radiographs of implants at a single centre, collected from January 2015 to August 2016, was measured by the four individual investigators. A comparison of the digital calliper reading with the known implant size, taken from operation reports and company implant data, was conducted. Magnification scales were created for different anatomic regions: femur, tibia, humerus, elbow, wrist and hand, foot and ankle.

RESULTS

Precise regional scaling factors increase accuracy of digital radiography. Average magnification for hand, wrist, ankle and forearm is 5% (1-16%). Average magnification for foot, knee, tibia and elbow is 8% (3-11%). Humerus magnification is 10.3% (3-17%) and shoulder and femur approximately 15% (12-18%). Inter-rater Pearson's R reliability testing is 0.985-0.995 and intra-observer reliability is 0.998.

DISCUSSION

Applying regional scaling factors improves accuracy of digital imaging, therefore improving clinical decision-making regarding fractures, distance from bony landmarks, component sizing and reduction assessment. Femoral and tibial fracture measurements with appropriate scaling factors allow the accurate estimation of nail diameter required for fixation and screw diameter for fragment fixation.

Pre-operative templating for knee arthroplasty shows low accuracy with standard X-rays

OBJECTIVES

The purpose of this study was to evaluate the accuracy and reliability of pre-operative templating in predicting the size of femoral and tibial components and the effect of coronal deformity on templating accuracy.

METHODS

This was a retrospective study of 39 pre-operative templates prepared by three different surgeons with different levels of training. The accuracy and reliability measures were evaluated by alpha and kappa coefficients of agreement. The analysis of the effect of coronal deformity on the accuracy of the template was measured by the Spearman's correlation test.

RESULTS

Templating was accurate for the femoral component in 28.21% of anterposterior (AP) radiographs and 35.90% of lateral radiographs. Kappa coefficients were respectively 0.111 (95% confidence interval [95%CI]: -0.19 to 0.241) and 0.200 (95%CI: -0.010 to 0.401), indicating poor agreement. Templating accuracy for the tibial component were, respectively, 37.61% and 47.01% for AP and lateral views. Kappa coefficients were 0.186 (95%CI: -0.070 to 0.379) for the AP view and 0.315 (95%CI: -0.199 to 0.431) for the lateral view, showing poor and slight agreement respectively. Considering a margin of error of ±1 sizes, the agreement level improved for all components, particularly for tibia, where agreement levels become very good. The inter-observer agreement was fair for all components, except for the lateral view of the femoral component, whose agreement was good. The Spearman correlation test showed no correlation between accuracy of templating and coronal deformity.

CONCLUSION

Pre-operative templating is an unreliable and inaccurate tool. There is no relation between coronal deformity and accuracy of templating.

Fallacies of CT based component size prediction in total knee arthroplasty - Are patient specific instruments the answer?

BACKGROUND

The purpose of the study was to assess the accuracy of tibial and femoral component size prediction using computerised tomography (CT) based patient specific instruments in total knee arthroplasty.

METHODS

Eighty-eight knees in 58 patients underwent total knee arthroplasty (TKA) using CT based patient specific instruments between March 2015 to April 2016. All patients were assessed for the pre operative femoral and tibial component sizes predicted by the CT-based pre-operative plan. These sizes were compared with the actually implanted sizes during surgery, and the results were assessed. The data were evaluated using Wilcoxon signed rank tests, and p value set at <0.05 for significance.

RESULTS

Approximately 72% predicted tibia sizes matched the final implanted sizes whereas 66% femoral implants matched their pre-operative predicted sizes. The difference in the tibial implant size was not statistically significant (p-value > 0.05). However, the difference in the femoral size was statistically significant (p-value 0.009). The downsizing of the tibial component was needed in 14.8% knees whereas upsizing was required in 13.6% of the knees. At the femoral side, 22.7% components required downsizing at the time of implantation as compared to 11.4% components wherein a bigger component was used.

CONCLUSIONS

We conclude that size prediction using CT-based technology for patient specific instrumentation is not fool proof. The size prediction accuracy for femoral and tibial components at 66% and 72% are low and cannot be relied upon at present. The patient specific technology using CT scan based jigs holds promise for the future, needs refining and fine tuning.

Patient-specific instruments for total knee arthroplasty can accurately predict the component size as used peroperative

PURPOSE

Patients-specific instruments (PSI) for implantation of total knee arthroplasty (TKA) can be used to predict the implant size for both the femur and the tibia component. This study aims to determine the impact of approval of the PSI planning for TKA on the frequency of, and reason for intraoperative changes of implant sizes.

METHODS

The clinical records of 293 patients operated with MRI- (90.4 %) and CT-based (9.6 %) PSI were reviewed for actual used implant size. Preoperative default planning from the technician and approved planning by the operating surgeon were compared with the intraoperative implanted component size for both the femur and tibia. Intraoperative reason for not following the default sizes was outdated. Furthermore, MRI- and CT-based PSI were compared for these outcomes.

RESULTS

In 93.9 and 91.1 % for, respectively, the femur and tibia (n.s.), the surgeon planned size was implanted during surgery. The predicted size of the femur (p < 0.00) and the tibia (p < 0.00) component planned by a technician differed from the implanted component sizes in 62 (21.2 %) and 51 (17.4 %) patients, respectively. In 17 cases, the femoral component size was adapted intraoperative based on the expert opinion of the operating surgeon. In 26 cases, the tibia component was changed during the surgery because of a mediolateral overhang, sclerotic bone, medial or lateral release, limited extension and/or fixed varus deformity. The results between the MRI- and CT-based PSI did not differ (n.s.).

CONCLUSIONS

PSI is a tool to help the surgeon to achieve the best possible results during TKA. The planning made by a technician should always be validated and approved by the operating surgeon who has the ultimate responsibility regarding the operation. With PSI, the operating surgeon is able to minimize intraoperative implant size errors in advance to improve operating room efficiency with possible lowering hospital costs per procedure.

LEVELS OF EVIDENCE

III.

2D versus 3D templating in total knee arthroplasty

BACKGROUND

Preoperative digital templating in total knee arthroplasty (TKA) helps to determine the need of non-standard implants, prophesies the bony resections and helps to anticipate the intraoperative plan. Templating within the process of patient specific instrumentation (PSI) is fairly new and 2D planning has not been compared to PSI templating.

METHODS

94 patients underwent unilateral primary TKA with magnetic resonance imaging (MRI) based preoperative templating and PSI cutting blocks. Parallel to this, three observers templated all cases using digital planning on standard preoperative x-rays. The examiners templated all cases independently and were blinded to the component sizes used intraoperatively.

RESULTS

Three-dimensional (3D) templating was accurate in predicting the correct implant size in 100% of the cases. The femoral and tibial two-dimensional (2D) digital templating varied from 43.6% to 59.5% and 52.1% to 68% of the cases. When allowing ±1 difference, femoral 2D digital templating varied from 93.6% to 97.8% of the cases and ranged from 94.6% to 98.9% on the tibial side. All observers show "very good" correlation. The coefficient indicates a very good agreement in between the three observers.

CONCLUSION

3D templating has very high accuracy for the actual implant size prediction. Compared to this, 2D digital templating is an accurate method to approximately (±1 size) determine the size of TKA components. However, we judge this technique accurate enough, that 2D templating allows launching Template-directed instrumentation (TDI), while the examiner does not need a high level of clinical experience.

CLINICAL RELEVANCE

Within the process of digital planning, the surgeonmight focus evenmore on the upcoming operation.

Template-Directed Instrumentation Reduces Cost and Improves Efficiency for Total Knee Arthroplasty: An Economic Decision Analysis and Pilot Study

Template-directed instrumentation (TDI) for total knee arthroplasty (TKA) may streamline operating room (OR) workflow and reduce costs by preselecting implants and minimizing instrument tray burden. A decision model simulated the economics of TDI. Sensitivity analyses determined thresholds for model variables to ensure TDI success. A clinical pilot was reviewed. The accuracy of preoperative templates was validated, and 20 consecutive primary TKAs were performed using TDI. The model determined that preoperative component size estimation should be accurate to ±1 implant size for 50% of TKAs to implement TDI. The pilot showed that preoperative template accuracy exceeded 97%. There were statistically significant improvements in OR turnover time and in-room time for TDI compared to an historical cohort of TKAs. TDI reduces costs and improves OR efficiency.

Reproduction of Hip Offset and Leg Length in Navigated Total Hip Arthroplasty: How Accurate Are We?

This study assesses how accurately we can restore hip offset and leg length in navigated total hip arthroplasty (THA). 152 consecutive patients with navigated THA formed the study group. The contra-lateral hip formed control for measuring hip offset and leg length. All radiological measurements were made using Orthoview digital software. In the normal hip offset group, the mean is 75.73 (SD- 8.61). In the reconstructed hip offset group, the mean is 75.35 (SD - 7.48). 95.39% had hip offset within 6 mm of opposite side while 96.04% had leg length restored within 6 mm of contra-lateral side. Equivalence test revealed that the two groups of hip offsets were essentially the same. We conclude that computer navigation can successfully reproduce hip offset and leg length accurately.

Reliability of preoperative measurement with standardized templating in Total Knee Arthroplasty

AIM: To investigate the correlation between preoperative measurement in total knee arthroplasty and the prosthetic size implanted.

METHODS: A prospective double-blind study of 50 arthroplasties was performed. Firstly, the reliability and correspondence between the size of said measurement and the actual implant utilized was determined. Secondly, the existing correlation between the intra- and interobserver determinations with the intraclass correlation coefficient was analyzed.

RESULTS: An overall correspondence of 54%, improving up to 92% when the measured size admitted a difference of one size, was found. Good intra- and interobserver reliability with an intraclass correlation coefficient greater than 0.90 (P < 0.001) was also discovered.

CONCLUSION: Agreement between the preoperative measurement with standardized acetate templates and the prosthetic size implanted can be considered satisfactory. We thus conclude it is a reproducible technique.

The accuracy and inter-observer reliability of acetate templating in total hip arthroplasty

AIM

The accuracy and inter-observer reliability (IOR) of acetate templating on hard copy X-rays in 33 primary total hip arthroplasties as measured by consultant and trainee surgeons was analyzed to find out how accurate are junior surgeons undertaking specialty training.

METHODS

The study was questionnaire-based using a prospective cohort over a 4 weeks period. The Surgeon measurements of acetabular cup, femoral stem and femoral offset sizes were noted following acetate measurements and then compared with the final implant chosen during surgery.

RESULTS

Prediction of sizing to within one size of the final match size was 75% accurate for cup and 91% accurate for femoral stem. Prediction of exact femoral offset sizes was 91% accurate. Templating showed strong IOR between senior consultant surgeon and junior trainee registrar within one size for cup (83%) and stem (100%) and for exact hip offset prediction (92%).

CONCLUSION

We conclude that acetate templating on hard copy X-rays is beneficial to surgeons to gauge acetabular cup and femoral stem size to within one size range. This further helps in predicting nearly exact femoral offset size.

Comparing the accuracy of radiographic preoperative digital templating for a second- versus a first-generation THA stem

This study assessed the accuracy of preoperative digital templating for a second-generation cementless stem compared with its first-generation design. A prospective cohort of 100 consecutive patients who had undergone a primary total hip arthroplasty using a new second-generation cementless stem was compared with the prior 100 hips that had received the first-generation stem. The authors believe that the second-generation stem may allow equal or more accurate digital templating compared with its predicate design.

Template-directed instrumentation in total knee arthroplasty: cost savings analysis

The use of digital radiography and templating software in total knee arthroplasty (TKA) continues to become more prevalent as the number of procedures performed increases every year. Template-directed instrumentation (TDI) is a novel approach to surgical planning that combines digital templating with limited intraoperative instruments. The purpose of this study was to evaluate the financial implications and radiographic outcomes of using TDI to direct instrumentation during primary TKA. Over a 1-year period, 82 consecutive TKAs using TDI were retrospectively reviewed. Patient demographics and preoperative templated sizes of predicted components were recorded, and OrthoView digital planning software (OrthoView LLC, Jacksonville, Florida was used to determine the 2 most likely tibial and femoral component sizes for each case. This sizing information was used to direct component vendors to prepare 3 lightweight instrument trays based on these sizes. The sizes of implanted components and the number of total trays required were documented. A cost savings analysis was performed to compare TDI and non-TDI surgical expenses for TKA. In 80 (97%) of 82 cases, the prepared sizes determined by TDI using 3 instrument trays were sufficient. Preoperative templating correctly predicted the size of the tibial and femoral component sizes in 90% and 83% of cases, respectively. The average number of trays used with TDI was 3.0 (range, 3-5 trays) compared with 7.5 (range, 6-9 trays) used in 82 preceding non-TDI TKAs. Based on standard fees to sterilize and package implant trays (approximately $26 based on a survey of 10 orthopedic hospitals performing TKA), approximately $9612 was saved by using TDI over the 1-year study period. Overall, digital templating and TDI were a simple and cost-effective approach when performing primary TKA.

The accuracy of digital templating: a comparison of short-stem total hip arthroplasty and conventional total hip arthroplasty

PURPOSE

Selection of the correct femoral stem size is crucial in total hip arthroplasty for an uncomplicated implantation and good initial stability. Pre-operative templating has been shown to be a valuable tool in predicting the correct implant size. For short-stem total hip arthroplasty (SHA), which recently is increasingly used, it is unknown if templating can be performed as reliable as conventional total hip arthroplasty (THA).

METHODS

A total of 100 hip arthroplasties, 50 with SHA and 50 with THA, were templated by four orthopaedic surgeons each. The surgeons had different levels of professional experience and performed a digital template of the acetabular and femoral component on the pre-operative radiographs. The results were compared with the truly inserted implant size.

RESULTS

For the femoral stems the average percentage of agreement (± 1 size) was 89.0 % in SHA and 88.5 % in THA. There was no significant difference among surgeons in the accuracy of templating the correct stem size and no significant difference between templating SHA and THA. For the acetabular component the average percentage of agreement (± 1 size) was 75.8 %. However, the more experienced surgeons showed a significant higher accuracy for templating the correct cup size than the less experienced surgeons.

CONCLUSION

Digital templating of SHA can predict the stem sizes as accurately as conventional THA. Therefore digital templating is also recommendable for SHA, as it helps to predict the implant size prior to surgery and thereby might help to avoid complications.