PURPOSE:To compare early patient-reported clinical outcomes of patient-individual total knee arthroplasty (TKA) with individualized trochlear design versus robotic-assisted TKA using off-the-shelf implants in patients with valgus knee phenotypes and pronounced femoral valgus (lateral distal femoral angle [LDFA] < 85°) at 3 and 12 months postoperatively in a prospective matched case-control study. METHODS:This prospective matched case-control study based on predefined anatomical criteria included 42 patients who underwent primary TKA between October 2021 and October 2023. Twenty-one patients received patient-individual posterior-stabilized implants. Twenty-one matched controls underwent robotic-assisted TKA with off-the-shelf implants. All procedures followed restricted kinematic alignment (KA) principles with valgus undercorrection. Primary outcomes were patient-reported scores (Forgotten Joint Score [FJS], Kujala Score, Oxford Knee Score [OKS] and the Western Ontario and McMaster Universities Arthritis Index [WOMAC]), assessed preoperatively and at 3 and 12 months. RESULTS:Both groups demonstrated comparable preoperative clinical status and comparable degrees of preoperative valgus deformity, with no significant differences in hip-knee-ankle angle (HKA, 185.6 ± 6.3° vs. 188.8 ± 4.1°; p = 0.060) or mechanical LDFA (84.0 ± 0.9° vs. 83.7 ± 1.2°; p = 0.261). At 3 and 12 months, patient-individual total knee arthroplasty (pTKA) demonstrated significantly better scores across all patient-reported outcome measures (PROMs) (p < 0.05). The largest difference was observed in the Kujala score at 12 months (79.5 ± 12.8 vs. 59.7 ± 19.0, p = 0.001). FJS improved more rapidly in the pTKA group (from 9.0 to 49.1 at 3 months, and 52.5 at 12 months) compared to robotic-assisted total knee arthroplasty (rTKA) (26.9 and 36.0, respectively). One revision for suspected infection occurred in the pTKA cohort; none were reported after rTKA. CONCLUSIONS:Patient-individual TKA with individualized trochlear design achieved superior early functional outcomes compared to robotic-assisted TKA with standard implants in severe valgus morphotypes. Individualized trochlear orientation may improve patellofemoral mechanics and facilitate faster recovery in patients with severe femoral valgus. LEVEL OF EVIDENCE:Level III.

Single-stage knee revision arthroplasty under special consideration of bony defects and soft tissue laxity over the full arc of motion. Aseptic loosening, ligamentous instability, or outlier in implant position requiring single-stage knee revision arthroplasty. Cases with severe bone loss or ligamentous instability requiring a hinged prosthesis. Loss of knee extensor function. After establishment of a standardized median parapatellar approach and setup of the imageless robotic system, the implant is mapped while still in situ. The bone–implant interface is highlighted in the 3D reconstruction of the implant by the application of special points during mapping. Soft tissue balance is registered and the component position of the revision implant is determined in the virtual implant planning stage. The implant is then removed and the surgical plan is executed with the robotic bur. If necessary, augments can be used to account for excessive bone loss and reconstruct the native joint line. Full weight-bearing as tolerated, free range of motion. In the literature, robotic-assisted knee revision arthroplasty has mainly been described in the form of case reports and smaller case series; the authors report generally favorable results.

PurposeA periprosthetic joint infection (PJI) is considered the most drastic complication after hip/knee arthroplasty. Despite extensive research into PJI treatment, insights into patients’ biopsychosocial needs are sparse. The aim of the current review is to provide an overview of patients’ biopsychosocial needs and interventions aimed at these needs. MethodsA systematic review incorporating a comprehensive database search of seven major scientific databases. Articles were included if they reported on the biopsychosocial needs of patients with PJI and on interventions aimed at these needs. Quality of the included studies was assessed by two reviewers with the Mixed Methods Appraisal Tool. Characteristics of included studies and the associated results were extracted. ResultsOf the 9,745 identified research articles, 20 were included in the review. All of the included articles reported about biopsychosocial needs, but only two (10%) of them also reported on interventions focused on these needs. Psychological needs were reported most often (n = 19, 95%), followed by physical (n = 14, 70%) and social needs (n = 8, 40%). Improving mental health was the most frequently reported psychological need (n = 13, 65%). Functional improvement emerged as the most common identified physical need (n = 12, 60%), while social support from healthcare professionals (n = 5, 25%) was the most reported social need. ConclusionThe results show a clear need for interventions on top of the primary surgical treatment for patients diagnosed with PJI, especially for psychological and physical support. Interventions targeting needs were described in only two articles (10%) in the current literature. Future studies should explore patient-centered approaches and integrate psychological and physical management into PJI treatment pathways to improve outcomes.

Background and Objective:Despite favorable objective outcomes, 20% of patients report dissatisfaction after total knee arthroplasty (TKA). This study analyzed early changes in patient satisfaction and associated biopsychosocial parameters from two to twelve months postoperatively. # Methods The FInGK study was a prospective cohort study including 227 patients who underwent elective TKA between December 2019 and May 2021 at a German university hospital. Data were collected preoperatively (t0), as well as at two (t1) and twelve months (t2) postoperatively via self-reported questionnaires including Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC Score), WHO Well-Being Index (WHO-5 Score), and patient satisfaction. Patients were stratified into four satisfaction groups (Satisfied/Satisfied (n=129), Not-Satisfied/Satisfied (n=23), Satisfied/Not-Satisfied (n=26), Not-Satisfied/Not-Satisfied (n=46)) based on their satisfaction pattern at t1 and t2. Results:Overall minimally clinically important improvements in WOMAC Score (47.3 to 69.0 to 76.5) and improvements in WHO-5 Score (43.7 to 59.1 to 66.4) were observed in the total study population from preoperative to two and twelve months postoperatively. One third of patients reported dissatisfaction at twelve months, being significantly younger (66.5 vs. 69.1 years; p=0.046) and more smokers (16.2 % vs. 6.5%; p=0.021). 21.9% experienced satisfaction changes: 11.6% switched from satisfied (t1) to dissatisfied (t2). Conversely, 10.3% improved from dissatisfied to satisfied, demonstrating gains between t1 and t2. Conclusion:We identified a variety of patient groups, each exhibiting distinct levels of satisfaction and biopsychosocial profiles after TKA. Further studies with larger sample sizes are needed to examine early postoperative outcomes and changes over time after TKA.

Aims The Coronal Plane Alignment of the Knee classification (CPAK) describes nine knee phenotypes by defining arithmetic hip-knee-ankle angle (aHKA) and joint line obliquity (JLO). In this study, the CPAK classification was used to analyze the development of lower-limb alignment in children and adolescents, providing reference values and allowing insights into the morphogenesis of the knee joint during skeletal maturation. Methods Angular measurements of 655 knees taken on CT scans of 333 children aged between four and 18 years from a publicly available radiological database were analyzed, applying the CPAK classification by calculating the aHKA and JLO. Results The mean aHKA was 3.4° (SD 3.1°). JLO became more pronounced with age, decreasing from a mean of 176.8° (SD 4.2°) at the age of four years to 172.8° (SD 3.1°) at the age of 18 years. The most common CPAK type between four and 18 years was CPAK III (58.2%), the second most common type was CPAK II (24.7%), and the third most prevalent type was CPAK IV (10.1%). Conclusion This is the first study analyzing lower-limb alignment in children and adolescents using the CPAK classification. By simultaneously developing a distal femoral valgus and a counteracting proximal tibial varus morphology, overall constitutional alignment as represented by the aHKA remains almost constant between the age of four and 18 years. Conversely, joint line obliquity changes significantly with age towards an apex distal phenotype. We provide a comprehensive explanation for the physiological development of lower-limb alignment during skeletal growth. Cite this article: Bone Jt Open 2026;7(8):1084–1092.

Tibial plateau fractures are severe injuries of the knee joint and oftentimes lead to the development of posttraumatic osteoarthritis. A proportion of patients therefore requires secondary arthroplasty. Total knee arthroplasty after tibial plateau fracture, however, carries a markedly higher risk for complications when compared to primary arthroplasty, especially in geriatric patients. Bone defects, malalignment, instability, and a higher infection rate are major concerns in this subset of patients. Retained hardware and compromised soft tissues may further complicate surgical treatment. Careful preoperative surgical planning is therefore essential. Implant design, augmentation, and degree of constraint have to be adapted to individual soft-tissue tension and bony defects. Osseous defects are classified using the Anderson Orthopaedic Research Institute (AORI) classification and implant fixation is facilitated by respecting the concept of zonal fixation. Modern technologies such as robotic surgery systems and patient-specific instrumentation may further reduce surgical complexity in difficult cases. The following article provides an overview of challenges and surgical strategies in total knee arthroplasty after tibial plateau fractures. Three cases illustrate specific challenges and individualized treatment options.

Aims:The Coronal Plane Alignment of the Knee classification (CPAK) describes nine knee phenotypes by defining arithmetic hip-knee-ankle angle (aHKA) and joint line obliquity (JLO). In this study, the CPAK classification was used to analyze the development of lower-limb alignment in children and adolescents, providing reference values and allowing insights into the morphogenesis of the knee joint during skeletal maturation. Methods:Angular measurements of 655 knees taken on CT scans of 333 children aged between four and 18 years from a publicly available radiological database were analyzed, applying the CPAK classification by calculating the aHKA and JLO. Results:The mean aHKA was 3.4° (SD 3.1°). JLO became more pronounced with age, decreasing from a mean of 176.8° (SD 4.2°) at the age of four years to 172.8° (SD 3.1°) at the age of 18 years. The most common CPAK type between four and 18 years was CPAK III (58.2%), the second most common type was CPAK II (24.7%), and the third most prevalent type was CPAK IV (10.1%). Conclusion:This is the first study analyzing lower-limb alignment in children and adolescents using the CPAK classification. By simultaneously developing a distal femoral valgus and a counteracting proximal tibial varus morphology, overall constitutional alignment as represented by the aHKA remains almost constant between the age of four and 18 years. Conversely, joint line obliquity changes significantly with age towards an apex distal phenotype. We provide a comprehensive explanation for the physiological development of lower-limb alignment during skeletal growth.

To evaluate whether imageless handheld robotic-assisted total knee arthroplasty (rTKA) can achieve time neutrality compared with manual TKA (mTKA) within a standardised workflow, while assessing operating-room (OR) efficiency, environmental impact, and intraoperative workload demand. In this prospective study, 24 consecutive patients undergoing primary TKA were stratified to either rTKA (n = 12) or mTKA (n = 12). A process analysis captured 75 timestamps per case and quantified preparation, surgical, breakdown, turnover, and total OR times. Instrument trays were counted and weighed; reprocessing-related water and electricity consumption and costs were estimated. Perceived workload demand was assessed after both rTKA and mTKA using the NASA Task Load Index. No statistically significant differences were observed between rTKA and mTKA for any OR time interval (total OR time 79.8 ± 8.1 vs. 75.8 ± 5.3 min, p = 0.19; mean surgical time 40.3 ± 4.2 vs. 37.3 ± 3.9 min, p = 0.10 for rTKA vs. mtKA respectively). The reduction of one tray for rTKA cases corresponded to estimated savings of €13,900, 3,900 L of water, and 140 kWh of electricity in sterilisation based on an annual volume of 250 cases. For rTKA, the NASA-TLX domain scores demonstrated lower perceived workload and frustration for rTKA than for mTKA (all p < 0.001), with a significantly higher perceived performance rating (p = 0.025). Imageless handheld rTKA achieved time neutrality compared with mTKA in a standardised high-volume workflow and was associated with reduced intraoperative workload demand. These findings support the feasibility of integrating handheld robotic assistance without compromising OR efficiency, while potentially improving staff experience and reducing resource utilisation, thereby contributing to value-based arthroplasty care.

Standard x-ray radiography is routinely used to monitor total knee arthroplasty (TKA) postoperatively for complications such as loosening, malpositioning and insert wear. However, the radiolucency of the polyethylene insert makes quantitative wear assessment challenging. This study investigates the integration of radiopaque markers into standard ultra-high molecular weight polyethylene (UHMWPE) inserts to enhance their radiographic visibility and enable quantitative wear assessment from standard radiographs. Preliminary experiments established suitable process parameters for micro-milling cavities into UHMWPE. Final inserts were machined with varying microstructure configurations comprising grooves and holes. These microstructures were filled with a radiopaque composite of high-density polyethylene (HDPE) +20 wt.% barium sulphate (BaSO4) composite via extrusion. HDPE was employed as a substitute for UHMWPE due to processability challenges resulting from the latter's high melt viscosity. The marker-integrated inserts were successively fitted on a phantom knee setup fitted together with TKA components and radiographed in the anteroposterior view. A weighted scoring model was created to identify optimal marker geometries based on edge visibility, dimensional measurability, homogeneity, and implant-induced obscuration of the marker projections in standard radiographs. Vertical groove markers i.e. those oriented in parallel to the central ray exhibited superior radiographic visibility and measurability compared to horizontal grooves. Hole markers exhibited a higher homogeneity and were easier to fill, but showed slightly reduced radiographic edge definition in comparison to the vertical grooves. Overall, the vertical grooves were identified as the most favourable marker geometry, followed by the holes, whereas horizontal markers performed the poorest. The findings of this study provide a proof of concept for incorporating radiopaque markers into TKA inserts, establishing a methodological framework for futurein vitrowear measurement based on dimensional marker change analysis. Further research into the development of a UHMWPE-compatible marker material is required before clinical relevance can be achieved.

Abstract Purpose Revision total knee arthroplasty is a complex and technically demanding procedure, with an increasing global incidence. This complexity heightens the cognitive and physical demands of surgical teams, contributing to elevated burnout, musculoskeletal injuries and psychological stress. This European wide multi‐centre observational evaluation assessed the impact of a handheld robotic‐assisted surgical system on intra‐operative workload using the NASA Task Load Index instrument to compare robotic‐assisted and manual instrumentation approaches during revision knee arthroplasty. Methods Data were collected from 212 surveys following 100 revision knee arthroplasty procedures, capturing subjective workload measures across six NASA Task Load Index domains from surgeons and peri‐operative theatre staff. Results The results demonstrated a significant reduction in the overall workload with robotic‐assistance compared with manual instrumentation (median overall workload score 0.0 vs. 8.5 respectively, p = 0.0003). Domain‐specific analyses revealed significantly lower mental demand, physical demand and effort in the robotic‐assisted group without compromising perceived surgical performance, temporal demand, or frustration. A subgroup analysis of the lead surgeons showed consistent perceived workload reductions consistent with the overall findings. These results suggest that the handheld robotic‐assisted surgical system may mitigate cognitive and physical strain during complex revision knee arthroplasty procedures. Conclusions This evaluation underscores the potential of robotic‐assisted technology to enhance surgical ergonomics, reduce surgeon fatigue and improve well‐being, which may translate into sustained surgical performance. Future work should incorporate objective ergonomic measures, expand participant roles and explore long‐term impacts on clinical outcomes and staff welfare. Level of Evidence Level II.

Musculoskeletal tumor surgery is characterized by its interdisciplinary nature, complexity, and individualized approach. The primary objective is an R0 resection-a complete removal of the tumor with clear margins-in order to reduce the risk of recurrence and improve long-term survival. A careful, individualized balance must be struck between the extent of resection required from an oncological perspective and the amount of tissue or function to be preserved from a functional perspective. Classic resection techniques, such as those described by Enneking and Durham, can be customized through the use of modern assistance systems. These systems are collectively referred to as "computer-assisted surgery" (CAS) systems and have undergone a remarkable evolution over the past 20 to 25 years. They encompass image-based navigation, robot-assisted navigation, augmented reality navigation, and patient-specific instruments and implants (PSI). First studies have demonstrated the superiority of CAS systems over manual resection techniques with regard to achieving R0 resections and improving long-term survival outcomes. This article aims to introduce CAS systems and provide an outlook on potential avenues for future development.

Periprosthetic joint infection (PJI) represents a severe complication following total hip arthroplasty (THA) and total knee arthroplasty (TKA). The intraarticular application of vancomycin powder is increasingly integrated into perioperative standards as an innovative strategy for PJI prevention. Yet the efficacy of this method remains a topic of debate. The aim of this retrospective cohort study was to evaluate whether topical vancomycin application reduces the incidence of PJI after primary total joint arthroplasty (TJA) and whether it is associated with an increased risk of wound complications. In this retrospective monocentric cohort study, all primary THA and TKA procedures performed between January 1, 2022, and December 31, 2023, were analysed. From January 1, 2023, intraarticular vancomycin powder was implemented as part of the standard perioperative protocol for PJI prevention. The PJI rates, postoperative surgery-related complications, and time to infection were compared between the vancomycin and control groups. A total of 1,499 patients were included in the study. Patients were divided into two groups: a vancomycin group (VG, n = 818) and a control group (CG, n = 681). No statistically significant group differences were observed for wound healing disorders (p = 0.775) or PJI rates (1.0

The current literature remains inconclusive about whether kinematic alignment (KA) is superior to mechanical alignment (MA) in total knee arthroplasty (TKA). Therefore, this randomized controlled trial sought to provide further clarification. 39 MA patients, 33 KA patients, and 9 healthy controls were included. All participants underwent three-dimensional gait analysis on a treadmill one day before surgery and one year postoperatively. A preoperative range of motion (ROM) score was calculated and correlated with the postoperative Forgotten Joint Score (FJS). One year after surgery, no significant kinematic differences were observed between MA and KA. However, in Coronal Plane Alignment of the Knee (CPAK) type 1 patients, KA knees more closely reproduced the gait of healthy controls and showed higher walking speed. Correlation analysis revealed that patients with a higher preoperative ROM achieved better outcomes with KA, whereas female patients with lower ROM benefit more from MA. Although no kinematic differences were detected, the strong trend toward reduced joint space in MA compared to KA in CPAK type 1 patients may result from subtle deviations in joint-line restoration or postoperative soft-tissue tension. Both factors can affect load distribution and joint perception. The present findings support a patient-specific approach to alignment selection in TKA.

Die muskuloskelettale Tumorchirurgie zeichnet sich durch ihre Interdisziplinarität, Komplexität und Individualität aus. Ziel ist eine R0-Resektion, zur Reduktion des Rezidivrisikos und besseren Langzeitüberleben. Es ist individuell abzuwägen, wie viel aus onkologischer Sicht reseziert werden muss und aus funktioneller Sicht zu erhalten ist. Klassische Resektionsformen nach Enneking und Durham, lassen sich mit modernen Assistenzsysteme individualisieren. Diese Systeme werden als „Computer-assisted-surgery“-Systeme (CAS-System) zusammengefasst und haben in den letzten 20–25 Jahren eine bemerkenswerte Evolution durchlebt. Zu ihnen gehören die bildbasierte Navigation, robotergestützte Navigation, Augmented-Reality-Navigation und patientenspezifische Instrumente und Implantate (PSI). Erste Studien haben die Überlegenheit von CAS-Systemen gegenüber der manuellen Resektion im Hinblick auf R0-Resektionen und Langzeitüberleben belegen können. In dem hier verfassten Artikel sollen CAS-Systeme vorgestellt und ein Ausblick auf weitere Entwicklungsmöglichkeiten gegeben werden.

Robotic-assisted knee arthroplasty has gained popularity throughout the globe due to high accuracy of three-dimensional component placement. The next step in the utilization of robotic-assisted knee arthroplasty is its application in revision surgery or in complex primary cases with bony defects. This will be a challenge because bony defects and/or component malposition need to be taken into account when planning to achieve good outcomes. Three-dimensional planning can be utilized for appropriate component placement, while considering the placement of revision components, spacers, cones/sleeves and intramedullary stems. Improvement in surgical planning prior and during surgery using robotic assistance can help surgeons significantly during revision total knee arthroplasty procedures.

BACKGROUND:In total hip arthroplasty (THA), accurate reconstruction of physiological joint biomechanics is determined by the individual patient's proximal femoral anatomy and stem design. Previous studies demonstrated a wide variation of femoral canal shapes and an association with extramedullary geometrical features. The purpose of this study was to propose a comprehensive classification for the Coronal Plane Alignment of the Hip (CPAH) that incorporates intramedullary and extramedullary parameters. We sought to determine the distribution of femoral morphotypes in an osteoarthritic cohort and to assess the reconstructive potential of four common femoral stem designs in each CPAH type. METHODS:The preoperative radiographs of 2,345 patients undergoing primary uncemented THA were retrospectively analyzed, including Dorr classification, neck-shaft angle (NSA), femoral offset (FO), and femoral offset ratio. The CPAH classification defines nine morphotypes based on the combination of Dorr type and NSA. Each morphotype is categorized into a normal- and a high-offset subgroup. Digital templating was conducted to assess the reconstruction of FO, leg length, and the agreement between anatomy and stem geometry. RESULTS:The CPAH types 2N, 5N, 5H, 6N, and 8N accounted for a combined percentage of 82% (n = 1,928), whereas the remaining morphotypes represented less common anatomical constitutions. Canal shape, FO, and NSA were associated with demographic characteristics (age, P < 0.001; sex, P < 0.001). Subgroup analyses stratified by CPAH types revealed that the reconstructive potential of each stem design depends on the patient's femoral morphotype. Across all CPAH types, the short stem was the best-fit implant, whereas a mismatch between anatomy and stem design was evident in up to 80% of the cases using the anatomic stem design. CONCLUSIONS:The CPAH classification provides a comprehensive categorization of femoral morphotypes. It enables a phenotyping approach in THA planning and provides practical guidance for individualized implant selection.

Tibiakopffrakturen sind seltene, jedoch schwere Verletzungen des Kniegelenks. Häufig kommt es im Verlauf zur Entwicklung einer posttraumatischen Gonarthrose, die bei einem Anteil der Patienten eine endoprothetische Versorgung notwendig macht. Die sekundäre Implantation einer Kniegelenkendoprothese ist jedoch besonders bei geriatrischen Patienten komplex und geht mit einer im Vergleich zur primären Endoprothetik erhöhten Komplikationsrate einher. Achsabweichungen, knöcherne Defekte, Bandinstabilitäten und ein erhöhtes Infektionsrisiko stellen chirurgische Herausforderungen dar. Einliegendes Osteosynthesematerial und teils kompromittierte Weichteilverhältnisse können die Komplexität des Eingriffs weiter erhöhen. Prothesendesign, Augmentation und Kopplungsgrad müssen individuell an die vorhandene Bandstabilität und an knöcherne Defekte angepasst werden. Die Anwendung der AORI-Klassifikation (Anderson Orthopaedic Research Institute) ermöglicht eine einheitliche Einteilung knöcherner Defekte. Das Konzept der zonalen Verankerung erlaubt eine sichere und individualisierte Prothesenverankerung. Neben einer sorgfältigen präoperativen Planung kann der Einsatz robotischer Assistenzsysteme oder patientenspezifischer Instrumente dazu beitragen, die Komplexität der operativen Versorgung zu reduzieren. Der vorliegende Beitrag stellt eine Zusammenfassung spezifischer Herausforderungen der endoprothetischen Versorgung nach Tibiakopffraktur dar und zeigt operative Behandlungsstrategien anhand von drei klinischen Fallbeispielen auf.

Purpose:To develop and evaluate a time- and cost-efficient workflow for generating three-dimensional (3D) printable models of the pelvis and acetabulum using semiautomated segmentation with free and open-source software. The goal was to enable a streamlined production of individualized models suited for preoperative planning and education in primary and revision hip arthroplasty (THA). Methods:A semiautomated segmentation protocol was created using 3D Slicer and the TotalSegmentator module, followed by targeted manual refinement. This was compared to traditional manual segmentation using computed tomography (CT) data sets from patients undergoing complex primary or revision THA. The workflow was validated by two participants, who independently performed the segmentation and 3D printing process after studying the step-by-step guide as provided in this article for 8 native hips and 12 pathologically altered hip joints. Segmentation time, material use and print duration were recorded. A learning curve analysis was conducted via a logarithmic regression analysis. Results:The semiautomated workflow reduced segmentation time considerably compared to manual segmentation. Both investigators were able to learn and apply the workflow with increasing speed over successive trials, indicating a steep learning curve. Segmentation times amounted to a mean of less than 10 min after a learning curve of five segmentations in native hip models and eight segmentations for pathologically altered joints. The generated models were anatomically accurate and suitable for surgical planning. Cost analysis showed substantial savings compared to commercial outsourcing with mean costs of less than 5 euros for both native and pathological hip models. Conclusion:The presented workflow offers a fast, accessible, and low-cost method to produce patient-specific 3D models for THA planning. It can be adopted in most clinical environments using freely available software and standard 3D printers. This approach may help democratize access to 3D printing technology in orthopaedic surgery and lay the foundation for future clinical applications. Level of Evidence:Level IV.