Search Results (30)

This paper presents an open-source, fully parametric three-component total knee arthroplasty (TKA) implant system and an automated surgical planning pipeline, addressing the absence of publicly available, modifiable TKA design frameworks in the literature. A cruciate-retaining femoral component, tibial baseplate, and polyethylene insert were designed in Autodesk Fusion with 160 parameters governing all anatomically significant geometry. The femoral articulation surface uses a tangency-constrained triple-radius J-curve. An automated Blender (v. 5.1) Python pipeline performs bone model alignment, size selection from a twelve-size chart, Boolean resection via parametric cutting blocks, and final component placement. Prototypes were 3D printed and validated on 1:1 anatomical bone models. The implant system achieved flush seating on all resection surfaces and impingement-free articulation through the full range of motion on all bone sets. The pipeline correctly aligned bone models, performed resections, and selected appropriately sized implants in all 11 cases, processing each in 1–1.5 min. The system is the first open-source TKA framework to simultaneously provide full parametric definition, documented design rationale, three-component coverage, an automated planning pipeline, and an additive manufacturing fabrication path. By releasing the complete parametric model and pipeline as open source, this work enables independent validation, population-specific adaptation, and iterative improvement by the global research community. Full article

Unicompartmental knee arthroplasty (UKA) is an effective treatment for anteromedial osteoarthritis in carefully selected patients. Increasing attention has recently been directed toward restoration of pre-arthritic coronal alignment, supported by the use of the arithmetic hip–knee–ankle angle (aHKA) to estimate constitutional lower limb alignment. In medial UKA, kinematic alignment principles derived from the original technique described by Cartier et al. may help to reproduce native joint-line orientation while preserving physiological soft-tissue balance. This technical note details the indications, preoperative assessment, planning strategy, and operative steps of the procedure. Preoperative long-leg weight-bearing radiographs are used to estimate constitutional alignment through the aHKA and to plan the coronal inclination of the tibial cut. Intraoperatively, the distal position of the extramedullary guide is reproduced according to the preoperative planning in order to restore the native inclination of the medial tibial plateau. The sagittal tibial cut, posterior tibial slope, distal femoral cut, component sizing, gap assessment, and cementation technique are described, with emphasis on anatomical landmarks and technical pearls to improve reproducibility. The described technique provides a practical method for approximating constitutional coronal alignment in medial UKA without the use of robotic or navigated systems. The key feature of the procedure is accurate planning and execution of the tibial cut in both the coronal and sagittal planes in order to reproduce native joint-line orientation and preserve appropriate ligament balance. Full article

Background: Surgical management of adult patients with post-dysplastic coxarthrosis using total hip arthroplasty is technically demanding and carries an increased risk of complications. In cases of high iliac dislocation classified as Crowe type IV, restoring the acetabular component to the anatomical hip centre often requires femoral shortening osteotomy to enable safe reduction in the prosthetic joint. Nevertheless, long-term evidence on functional outcomes and prosthesis survival with this approach is limited. Methods: A retrospective cohort study included 19 patients with 22 cases of Crowe type IV post-dysplastic hip osteoarthritis treated with uncemented total hip arthroplasty (Pinnacle/S-ROM, DePuy, Warsaw, IN, USA) combined with transverse subtrochanteric femoral shortening osteotomy. Patients underwent serial clinical follow-up, including assessment of range of motion, measurement of limb-length discrepancy, and functional evaluation using the Harris Hip Score and the WOMAC questionnaire. Radiological assessment included evaluation of osteotomy union, implant positioning, and osteolysis on standardized radiographs. Vertical distances of the centre of rotation (CR), the tip of the greater trochanter (GT), and the tip of the lesser trochanter (LT) from both reference lines were measured bilaterally, and inter-side differences were calculated. The reference lines consisted of the line connecting the inferior margins of the ischial bones and the teardrop (TD) line. Results: All osteotomies united at a mean of 5.57 months, with a mean follow-up of 129 months. Mean limb-length discrepancy decreased from 5.27 cm to 1.5 cm, and mean hip flexion improved from 82.9° to 106°. Functional outcomes improved significantly, with mean WOMAC increasing from 55.4 to 80.1 (p < 0.001) and mean Harris Hip Score from 49.8 to 84.66 at up to 3 years of follow-up (p < 0.001). Osteotomy length correlated strongly with lesser trochanter–teardrop distance (p = 0.00000048). Complications included distal femoral fissure (27.3%) and revision (18%), with no infection or permanent neurological deficit. Conclusions: Total hip arthroplasty combined with subtrochanteric femoral shortening osteotomy for Crowe type IV post-dysplastic hip osteoarthritis appears to be a feasible and effective procedure in an experienced centre, providing reliable osteotomy healing and significant early functional improvement that is sustained over time. Limb-length discrepancy was reduced and satisfactory biomechanical restoration was achieved, with an acceptable complication profile and implant survival of 81.3% at long-term follow-up. The LT–TD parameter was identified as a potential predictor of osteotomy length, enabling the proposal of a preoperative planning equation. However, given the limited sample size and lack of validation, these findings should be interpreted cautiously. Further studies are needed to confirm their broader applicability. Full article

Background: The objective of this study was to evaluate the short-term clinical and radiological outcomes of a conservative cementless stem (Minima) in total hip arthroplasty (THA) for patients presenting with a narrow femoral canal. Methods: We retrospectively analyzed 18 patients (18 THAs) who received a size 1 Minima stem between 2018 and 2022. Clinical assessment was performed using the Harris Hip Score (HHS). Radiological evaluation focused on stem migration, trabecular bone development, cortical hypertrophy, and the presence of radiolucent or reactive lines. Implant survival was determined using Kaplan–Meier analysis. Results: The mean patient age was 51.6 years, with an average follow-up of 57 months. The mean HHS improved significantly from 38.3 preoperatively to 96.4 at the final evaluation (p < 0.001). Initial stem migration occurred in two hips (11.1%) within the first 6 postoperative months, with no further progression or loosening observed thereafter. Bony trabecular development was identified in Gruen zones 3 (27.8%), 4 (5.5%), and 5 (16.7%). Reactive lines were present around four stems (zones 3–5). One intraoperative complication (5.5%) occurred (acetabular component migration during trial reduction), which required screw fixation. No revisions were performed. Both clinical and radiological implant survival at the final follow-up was 100.0%. Conclusions: At a mean follow-up of 57 months, the use of the size 1 Minima stem in patients with a narrow femoral canal demonstrated excellent clinical and radiological outcomes. These findings suggest that this conservative stem is a reliable option for this specific patient population. Full article

Purpose: Revision total hip arthroplasty (RTHA) in the presence of a well-fixed femoral stem is associated with increased risk, as stem removal often results in bone loss, prolonged operative time, and greater blood loss. This problem is particularly relevant for older implants with a 14/16 taper, which is incompatible with most modern femoral heads. The Bioball™ System, a modular head–neck adapter, allows for acetabular or head-only revision while preserving the femoral stem. This study aimed to evaluate long-term clinical and radiological outcomes of RTHA using the Bioball™ System in patients with 14/16 tapers. Methods: A total of 38 patients (23 women, 15 men; mean age 73.5 years) met the inclusion criteria. All procedures were carried out with a well-fixed femoral stem and a 14/16 taper. Revisions were limited to exchange of the acetabular component, liner, or both, avoiding stem removal. The primary indication was acetabular cup loosening (n = 29, 76.3%); liner-only exchange was performed in 9 patients (23.7%). Clinical outcomes were assessed using the modified Merle d’Aubigné and Postel (MAP) score, and radiological evaluation focused on fixation, migration, and loosening. Mean follow-up was 8.44 years. Results: Both the acetabular component and liner were replaced in 76.3% of patients, while 23.7% underwent liner and head exchange only. Longer adapter sizes were most frequently used, and a 7.5° offset adapter was applied in 57.9% of cases. The modified MAP score improved by a mean of 5.7 points (p < 0.05), and VAS pain scores decreased from 7.4 to 2.6 (p < 0.05). No radiological signs of loosening were observed at final follow-up. Conclusions: The Bioball™ System enables effective restoration of hip stability and offset without femoral stem removal, offering favorable long-term clinical and radiological outcomes in revisions involving older 14/16 tapers. Full article

Background: Preoperative templating is an essential step in hip arthroplasty (HA), guiding implant selection and reducing surgical complications. It is typically performed using acetate templates or digital software. These methods, however, depend on the surgeon’s experience and may be limited by cost and availability. This study aimed to develop and validate a deep learning (DL) model using plain radiographs to predict implant sizes in HA. Methods: This retrospective study included patients who underwent primary HA using a cementless CORAIL^® femoral stem and PINNACLE^® acetabular cup. The DL model was trained on 688 preoperative anteroposterior (AP) hip radiographs and validated temporally on 98 additional cases. Implant sizes predicted by the DL model were compared with on-screen templating (acetate templates overlaid on digital images). The actual implanted size was used as the reference standard. Accuracy, mean absolute error (MAE), and root mean square error (RMSE) were calculated. Logistic regression was performed to identify factors influencing prediction accuracy. Results: The DL model showed higher accuracy than the on-screen templating for the acetabular cup (88.9% [77.4% to 95.8%] vs. 83.3% [70.7% to 90.2%]) and femoral stem components (85.7% [77.2% to 92.0%] vs. 81.6% [72.5% to 88.7%]), while the on-screen method performed better for the bipolar head (93.2% [81.3% to 98.6%] vs. 72.7% [57.2% to 85.0%]). MAE and RMSE were comparable between the methods for acetabular and femoral stem components (all p > 0.05), with statistically significant differences observed only in the bipolar head (p < 0.01 and 0.02, respectively). Although logistic regression analysis showed trends toward higher accuracy in acetabular size prediction among women and those with shorter height, no demographic factors were statistically significant predictors of accuracy. Conclusions: A DL model using only plain radiographs can accurately predict implant sizes in HA, particularly for the acetabulum and femoral stem. These findings suggest that the DL-based model could be a useful tool in preoperative planning. With further refinement to improve generalizability, this approach could be useful in a routine clinical setting in the future. Full article

Background: Robotic-assisted systems have transformed total knee arthroplasty (TKA), promising improved accuracy and intraoperative consistency, yet real-world data from non-academic centers remain limited. Objective: This study evaluates five-year clinical integration of a semi-autonomous, CT-based, robotic-arm-assisted TKA at a tertiary non-teaching hospital in Germany, focusing on planning accuracy, gap balancing, and intraoperative outcomes. Methods: We retrospectively analyzed all patients (n = 457) who underwent MAKO-assisted TKA from 2020 to 2025, performed by three orthopedic surgeons using a standardized subvastus approach. We assessed preoperative deformities, intraoperative alignment, implant sizing, and gap balancing. Surgical plans were adapted intraoperatively when indicated. Pre- vs. post-implantation values were compared using slopes to evaluate execution consistency. Results: Median patient age was 67.0 years (IQR: 60.0–75.0), with varus in 84.1% (7.0°, IQR: 4.0°–10.0°), valgus in 13.2% (3.0°, IQR: 1.5°–5.8°), and neutral alignment in 2.7%. Flexion contracture occurred in 80.4% (6.0°, IQR: 3.0–10.0%), hyperextension in 12.7% (2.0°, IQR: 1.5°–5.0°). Planning-to-execution consistency was high, even with plan adaptations. Slope values for alignment parameters were: tibial rotation in degrees (slope value: 1.0), femoral sagittal angle in degrees (0.8), tibial sagittal angle in degrees (0.9), coronal posterior condylar angle in degrees (0.9), femoral component size (1.0), tibial component size (1.0). Over 95% of cases showed ≤3.0° deviation between planned and final values. Bone resection concordance showed moderate agreement, with slopes from 0.8 (posterior medial femoral cut in mm) to 0.5 (lateral tibial cut in mm). Gap balancing improved at all stages, with reduced variability in medial/lateral extension and flexion gaps (all p < 0.05). Functional reconstruction showed significant improvements in extension, flexion, and deformities (all p < 0.001). Conclusions: Semi-autonomous, CT-based, robotic-arm-assisted TKA was successfully implemented in this non-academic setting, demonstrating acceptable intraoperative and functional reconstruction outcomes, supporting the feasibility of robotic-assisted surgery outside academic centers. Full article

Bone density is considered one of the many factors influencing bone structure and DNA preservation. For this reason, it is of interest in fields such as anthropology, palaeontology, and genetics. This study describes a method for bone density assessment by gradient centrifugation in Sodium Poly-Tungstate (SPT) solutions (from 2.1 to 2.6 g/cm³). Fifty milligrams of bone powder (size range of 20–50 µm) were used, with an average recovery of 89.9 (IC = 3.3% at 95% of probability). In the first phase of the experiment, the protocol was applied to ten femurs: three exhumed from the WWII mass grave of Ossero, three aged (43–50 years old) femurs from a museum collection and four fresh controls. In the subsequent phase, the analysis was extended to three petrous bones, three metacarpals, and three metatarsals exhumed from the WWII mass grave. The SPT density gradient profiles revealed marked differences among the three femur sample sets: more than 80% of the powder from control femurs was recovered in fractions with a density ≤ 2.2 g/cm³, whereas approximately 45% of the femurs from the mass grave showed a density > 2.6 g/cm³. The remaining three aged femurs displayed peculiar density patterns. Among the other bone types, metatarsals showed the lowest density values, followed by petrous bones and metacarpals. To detect degradation signatures, all nineteen bone powders were also analysed by ATR-FTIR. The femurs from the mass grave exhibited spectral features consistent with mineral recrystallisation and degradation of the organic phase, whereas the other three aged femurs showed peculiar spectral profiles; metacarpals, petrous bones and metatarsals showed intermediate spectra. PCA was applied to SPT and ATR-FTIR data, revealing correlations that support the SPT method as a novel tool for bone quality assessment. Although based on a limited sample size, this preliminary work demonstrates that SPT gradient analysis is an effective, low-cost, rapid and reliable method for assessing bone density, with potential applications in different disciplines studying aged bone samples. Lastly, principal component analysis (PCA) revealed a correlation between bone density and the yield of DNA recovered from the ten femoral specimens. Full article

Background and objectives: Patient-specific components (PSC) represent an innovative option for total knee arthroplasty (TKA) in advanced osteoarthritis. Their effectiveness, however, closely relies on accurate positioning. Our study investigates the accuracy achieved by means of an inertial-based extramedullary cutting guide and the postoperative clinical and radiographic outcomes. Methods and materials: This was a prospective, single-arm, pilot study involving patients undergoing primary TKA with YourKnee^TM PSC. Femoral and tibial bone resections were performed using the Perseus inertial-based extramedullary cutting guide. Postoperative mechanical alignment and component positioning were assessed by computed tomography. Clinical outcomes were evaluated preoperatively and at 1, 3, 6, and 12 months postoperatively by main knee function and clinical outcome measures. Results: The study population included a small cohort (n= 12, four females/eight males, mean age 69 ± 5.65 years, mean BMI 25.7 ± 3.8 kg/m², KL grade > 3) with no control group. The mean absolute error between the planned and obtained Hip–Knee–Ankle angle was 1.36° ± 1.06 and within ±3° of all cases. Mean coronal alignment error was 1.87° ± 0.87 and 1.67° ± 0.75 for the femoral and tibial components, respectively. The mean sagittal alignment error was 1.89° ± 1.24 and 2.45° ± 0.87 for the femoral and the tibial components, respectively. Patients showed significant improvement in clinical and functional scores within the first 6 months: OKS increased from 20.64 ± 2.77 at the preoperative screening to 42.27 ± 4.34 (p < 0.0001), total KSS rose from 90.64 ± 17.25 to 169.36 ± 23.57 (p < 0.0001), and FJS reached 85.09 ± 17.14 at 6 months (p = 0.0031), indicating excellent functional recovery and forgotten joint effect. Knee ROM improved from 90.91° ± 11.14 to 110.36° ± 8.44 (p < 0.0001). After 6 months, outcome scores plateaued, suggesting an early stabilization of clinical benefits. No signs of radiolucency were detected on X-rays at 3- and 12-month follow-ups. Conclusions: The Perseus inertial-based extramedullary cutting guide used in combination with the YourKnee^TM PSCs resulted in accurate intraoperative prosthesis positioning and significant improvements in clinical and functional outcomes at 6 months after surgery. Despite the small sample size and absence of a control group, the results suggest that such combination represents a viable option to conventional surgical instrumentation and current off-the-shelf prosthetic designs. Full article

Background and Objectives: A basicervical femoral fracture is a relatively uncommon type of proximal femoral fracture. However, as the proportion of proximal femoral fractures rises in conjunction with the aging of society, the absolute number of patients with basicervical femoral fractures is also increasing. Nevertheless, the optimal surgical methods for the treatment of basicervical femoral fractures remain a topic of debate. The aim of this study is to evaluate the failure rates of cephalomedullary nail fixation in basicervical femoral fractures based on reduction types. Methods: A retrospective analysis was conducted on 22 patients (22 hips) with AO/OTA 31-A1.2 hip fractures who had undergone treatment with a cephalomedullary nail (PFNA-II or Gamma-3) between March 2007 and February 2018. They were classified into three groups based on the reduction types: extramedullary (E), anatomical (A), or intramedullary (I). The intramedullary group included cases where the basicervical component was impacted into the medullary canal, while the extramedullary group comprised cases where the component was displaced beyond the medullary canal. The anatomical group consisted of specimens that exhibited complete anatomical reduction. This was determined by both the anteroposterior (AP) view and the lateral view using simple radiographs. Results: There were 13 patients (59.1%) in Group E and 9 patients (40.9%) in Group A. No patients were classified in Group I. Fixation failure occurred in four patients (18.1%, 4/22). In Group E, no patients exhibited fixation failure (0%, 0/13). In contrast, four patients in Group A demonstrated fixation failure (44.4%, 4/9). Group A exhibited a significantly higher incidence of fixation failure (0% vs. 44.4%, p =0.037) compared to Group E. Conclusion: In the treatment of low-energy basicervical femoral fractures with cephalomedullary nails, extramedullary reduction demonstrated a lower rate of fixation failure compared to anatomical reduction in this study. While definitive conclusions regarding its superiority cannot be drawn due to the limited sample size, extramedullary reduction may serve as a promising alternative to reducing the high fixation failure rate associated with this challenging fracture type. Full article

(1) Background: Analyses of retrieved inserts allow for a better understanding of TKA failure mechanisms and the detection of factors that cause increased wear. The purpose of this implant retrieval study was to identify whether insert volumetric wear significantly differs among groups of common causes of total knee arthroplasty failure, whether there is a characteristic wear distribution pattern for a common cause of failure, and whether nominal insert size and component size ratio (femur-to-insert) influence linear and volumetric wear rates. (2) Methods: We digitally reconstructed 59 retrieved single-model cruciate-retaining inserts and computed their articular load-bearing surface wear utilizing an optical scanner and computer-aided design models as references. After comprehensively reviewing all cases, each was categorized into one or more of the following groups: prosthetic joint infection, osteolysis, clinical loosening of the component, joint malalignment or component malposition, instability, and other isolated causes. The associations between volumetric wear and causes of failure were estimated using a multiple linear regression model adjusted for time in situ. Insert linear penetration wear maps from the respective groups of failure were further processed and merged to create a single average binary image, highlighting a potential wear distribution pattern. The differences in wear rates according to nominal insert size (small vs. medium vs. large) and component size ratio (≤1 vs. >1) were tested using the Kruskal–Wallis test and the Mann–Whitney test, respectively. (3) Results: Patients with identified osteolysis alone and those also with clinical loosening of the component had significantly higher volumetric wear when compared to those without both causes (p = 0.016 and p = 0.009, respectively). All other causes were not significantly associated with volumetric wear. The instability group differentiated from the others with a combined peripheral antero-posterior wear distribution. Linear and volumetric wear rates showed no significant differences when compared by nominal insert size (small vs. medium vs. large, p = 0.563 and p = 0.747, respectively) or by component (femoral-to-insert) size ratio (≤1 vs. >1, p = 0.885 and p = 0.055, respectively). (4) Conclusions: The study found increased volumetric wear in cases of osteolysis alone, with greater wear when combined with clinical loosening compared to other groups. The instability group demonstrated a characteristic peripheral anterior and posterior wear pattern. Insert size and component size ratio seem not to influence wear rates. Full article

Background: Recent advancements in hip arthroplasty aim to enhance the stability, longevity, and functionality of femoral implants. However, the distal fitting of femoral stems, often caused by metaphyseal–diaphyseal mismatch, remains a significant issue, particularly in patients with Dorr type A femora. Such mismatches can result in suboptimal implant performance, leading to potential complications. This study focuses on evaluating the anatomical compatibility of five representative single-tapered wedge mid–short stems with the mediolateral (ML) anatomy of the proximal femur in an East Asian population, where these mismatches are often more pronounced. Methods: A total of 742 patients from two hospitals, all of whom underwent unilateral primary total hip arthroplasty, were included in the study. The contralateral proximal femur was confirmed to have normal anatomy in each patient. Hip anteroposterior radiographs were used for measurements, which were standardized in conjunction with CT images. Key anatomical parameters were measured, including proximal and distal medial–lateral canal dimensions, vertical offset, and medial offset. Five femoral stem designs—Tri-lock^®, Taperloc^®, Anthology^®, Accolade II^®, and Fit^®—were evaluated. R programming was employed for a detailed fit analysis to match stem sizes with patient anatomy, categorizing the fit as proximal, simultaneous proximal–distal, or distal engagement. Results: Among the femoral stems analyzed, the Fit^® stem demonstrated the closest alignment with the regression line for ML widths in the study population (slope = 0.69; population ML slope = 0.38). This was followed by Accolade II^®, which had a slope of 0.83. In terms of offset options, the Accolade II^® offered the largest offset coverage, making it particularly suitable for this population. The fit analysis revealed that the Fit^® stem had the highest suitable fit rate (90.56%), followed by Accolade II^® (73.04%). Taperloc^®, Anthology^®, and Tri-lock^® had similar fit rates of approximately 59%. Overall, optimal results were obtained for 92.05% of the population in the automated fitting trial, regardless of the product type. Conclusions: When designing modern cementless femoral stems intended for press-fit fixation, it is crucial to account for the anatomical variations specific to the target population. In this study, Fit^® and Accolade II^® femoral components demonstrated superior compatibility with the femoral anatomy of the East Asian population, particularly in those with a higher incidence of Dorr type A femora. These stems, characterized by slimmer distal dimensions and high-offset options, appear to minimize metaphyseal–diaphyseal mismatch and associated complications. Full article

Collared femoral stems in total hip arthroplasty (THA) offer reduced subsidence and periprosthetic fractures but raise concerns about fit accuracy and stem sizing. This study compares collared and non-collared stems to assess the stem–canal fill ratio (CFR) and fixation indicators, aiming to guide implant selection and enhance THA outcomes. This retrospective single-center study examined primary THA patients who received Corail cementless stems between August 2015 and October 2020, with a minimum of two years of radiological follow-up. The study compared preoperative bone quality assessments, including the Dorr classification, the canal flare index (CFI), the morphological cortical index (MCI), and the canal bone ratio (CBR), as well as postoperative radiographic evaluations, such as the CFR and component fixation, between patients who received a collared or a non-collared femoral stem. The study analyzed 202 THAs, with 103 in the collared cohort and 99 in the non-collared cohort. Patients’ demographics showed differences in age (p = 0.02) and ASA classification (p = 0.01) but similar preoperative bone quality between groups, as suggested by the Dorr classification (p = 0.15), CFI (p = 0.12), MCI (p = 0.26), and CBR (p = 0.50). At the two-year follow-up, femoral stem CFRs (p = 0.59 and p = 0.27) were comparable between collared and non-collared cohorts. Subsidence rates were almost doubled for non-collared patients (19.2 vs. 11.7%, p = 0.17), however, not to a level of clinical significance. The findings of this study show that both collared and non-collared Corail stems produce comparable outcomes in terms of the CFR and radiographic indicators for stem fixation. These findings reduce concerns about stem under-sizing and micro-motion in collared stems. While this study provides insights into the collar design debate in THA, further research remains necessary. Full article

Aseptic loosening is the dominant failure mechanism in contemporary knee replacement surgery, but diagnostic techniques are poorly sensitive to the early stages of loosening and poorly specific in delineating aseptic cases from infections. Smart implants have been proposed as a solution, but incorporating components for sensing, powering, processing, and communication increases device cost, size, and risk; hence, minimising onboard instrumentation is desirable. In this study, two wireless, battery-free smart implants were developed that used passive biotelemetry to measure fixation at the implant–cement interface of the tibial components. The sensing system comprised of a piezoelectric transducer and coil, with the transducer affixed to the superior surface of the tibial trays of both partial (PKR) and total knee replacement (TKR) systems. Fixation was measured via pulse-echo responses elicited via a three-coil inductive link. The instrumented systems could detect loss of fixation when the implants were partially debonded (+7.1% PKA, +32.6% TKA, both p < 0.001) and fully debonded in situ (+6.3% PKA, +32.5% TKA, both p < 0.001). Measurements were robust to variations in positioning of the external reader, soft tissue, and the femoral component. With low cost and small form factor, the smart implant concept could be adopted for clinical use, particularly for generating an understanding of uncertain aseptic loosening mechanisms. Full article

Background: Accurate preoperative planning for total knee arthroplasty (TKA) is crucial. Computed tomography (CT)-based preoperative planning offers more comprehensive information and can also be used to design patient-specific instrumentation (PSI), but it requires well-reconstructed and segmented images, and the process is complex and time-consuming. This study aimed to develop an artificial intelligence (AI) preoperative planning and PSI system for TKA and to validate its time savings and accuracy in clinical applications. Methods: The 3D-UNet and modified HRNet neural network structures were used to develop the AI preoperative planning and PSI system (AIJOINT). Forty-two patients who were scheduled for TKA underwent both AI and manual CT processing and planning for component sizing, 20 of whom had their PSIs designed and applied intraoperatively. The time consumed and the size and orientation of the postoperative component were recorded. Results: The Dice similarity coefficient (DSC) and loss function indicated excellent performance of the neural network structure in CT image segmentation. AIJOINT was faster than conventional methods for CT segmentation (3.74 ± 0.82 vs. 128.88 ± 17.31 min, p < 0.05) and PSI design (35.10 ± 3.98 vs. 159.52 ± 17.14 min, p < 0.05) without increasing the time for size planning. The accuracy of AIJOINT in planning the size of both femoral and tibial components was 92.9%, while the accuracy of the conventional method in planning the size of the femoral and tibial components was 42.9% and 47.6%, respectively (p < 0.05). In addition, AI-based PSI improved the accuracy of the hip–knee–ankle angle and reduced postoperative blood loss (p < 0.05). Conclusion: AIJOINT significantly reduces the time needed for CT processing and PSI design without increasing the time for size planning, accurately predicts the component size, and improves the accuracy of lower limb alignment in TKA patients, providing a meaningful supplement to the application of AI in orthopaedics. Full article