Nico Verdonschot

Knee joint distraction is a joint-preserving treatment for younger patients (45-65 years) with tibiofemoral osteoarthritis, aiming to unload cartilage by temporarily separating the femur and tibia. The KneeReviver (KR) is a distraction device specifically developed for this purpose. Despite clinical successes, inter-patient variability in outcomes indicate a limited understanding of its mechanical behavior. This study evaluates the mechanical contribution of KR's bone pins and springs using finite element (FE) modeling. Variations in bone pin length, diameter, and the inclusion of KR's springs were assessed in terms of contact mechanics, initial joint gap creation, and gap narrowing under axial load. Results showed that smaller pin diameters, longer pin lengths, and the inclusion of springs increased cartilage contact pressures, reduced initial joint gaps, and led to earlier joint gap closure. These findings identify critical mechanical factors that may inform future device design, patient-specific configurations, and surgical application strategies.

Purpose: The aim of this scoping review was to compose an overview of existing literature on the influence of knee bone morphology and alignment on knee kinematics in healthy individuals. Methods: This review was conducted according to the methodological frameworks of Arksey and O'Malley and Levac et al. and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses extension for Scoping Reviews guidelines. A systematic PubMed search was performed to identify studies examining associations between knee bone morphology or alignment features and knee kinematics during movement in healthy individuals. Data were charted using a standardised form and categorised and summarised by individual bone (femur, tibia or patella) or as alignment feature. Results: A total of 2402 studies were initially identified. Following duplicate removal and eligibility screening, 29 studies were included. Knee kinematics were assessed using various techniques, including marker‐based motion capture systems and advanced dynamic magnetic resonance imaging (MRI) or computed tomography (CT) imaging, across diverse knee movement tasks. Thirteen femoral and seven tibial bone morphology features demonstrated statistically significant associations with knee kinematics, whereas only two patellar bone morphology features were statistically significantly associated. Additionally, sixteen different alignment features showed statistically significant associations with knee kinematics. The features most frequently associated with knee kinematics included lateral trochlear inclination, tibial slope, tibial tuberosity–trochlear groove distance and static patellar tilt angle. Conclusion: Although many reported associations were supported by only a limited number of studies, this review provides a comprehensive overview of relationships between knee morphology and kinematics in healthy individuals. The findings highlight the importance of considering bone morphology and alignment in kinematic assessment and contribute to a growing understanding of functional knee anatomy. The influence of patellar bone morphology on knee kinematics remains underinvestigated, underscoring the need for standardised, large‐scale studies to further advance clinical assessment and biomechanical understanding. Level of Evidence: Level III.

Introduction: Dynamic CT imaging may help to diagnose ulnar-sided wrist pain by analysing joint motion in normal and pathological wrists. In this study an automated 3-D workflow was developed to quantify ulnocarpal impaction and distal radioulnar joint stability with dynamic CT imaging in normal wrists during motion. The aim was to establish normal values which can be used as a reference. Methods: Dynamic CT scans were acquired from the dominant wrist of 59 healthy participants during three wrist movements: flexion–extension and radioulnar deviation were measured in 30 wrists and pronation–supination in 29. Ulnocarpal impaction was assessed with 3-D ulnar variance, reflecting proximal–distal translation of the distal radioulnar joint, and ulnocarpal proximity to the lunate and triquetrum. Distal radioulnar joint stability was evaluated using the 3-D epicentre and 3-D modified radioulnar line methods, which captured palmar–dorsal translation. Results: Minimal proximal–distal and palmar–dorsal translation of the distal radioulnar joint was observed across all wrist movements, although considerable inter-individual variation was notable. Three-dimensional ulnar variance did not increase during pronation. Ulnocarpal proximity to the triquetrum showed greater variation during wrist motion than to the lunate (median range 4.2–5.0 vs. 1.2–1.4 mm, respectively). Palmar–dorsal translation was larger during pronation–supination (3-D epicentre range 15.2%) than during flexion–extension and radioulnar deviation (7.7 and 9.3%, respectively). Conclusion: Dynamic CT imaging shows promise for evaluating the distal radioulnar joint during wrist motion. Normal values that quantify ulnocarpal impaction and distal radioulnar joint stability found in this study may serve as a reference for future research of ulnar-sided wrist pathology. Level of evidence: IV

Purpose: This exploratory study tested the hypothesis that total medial and lateral meniscus prostheses have no adverse effect on range of motion, kinematics and laxity of the knee joint. Furthermore, it was investigated whether the prosthesis kinematics were similar to the native meniscus kinematics during flexion and under knee loading. Methods: A dedicated knee testing rig was used to apply different flexion angles and joint loads to 13 cadaveric knee joints. Roentgen stereophotogrammetric analysis (RSA) was used to analyse the kinematics of the knee joint and the meniscus. For both the medial and lateral compartment, linear mixed models were used to make a comparison between the native condition, the meniscectomized knee joint, a meniscal allograft transplant and the meniscus prosthesis. A Lachman test was simulated to measure the effect of the different meniscal conditions on anteroposterior knee laxity, with and without the anterior cruciate ligament intact. Results: None of the meniscal conditions restricted range of motion or adversely affected joint kinematics. During flexion and loading, the medial and lateral meniscus prostheses translated over the tibial plateau in a comparable way as the native meniscus, although some differences were identified. Anteroposterior knee laxity was not significantly altered by any of the meniscal conditions. Conclusions: The artificial medial and lateral meniscus prostheses did not affect knee range of motion. Only minor differences in knee joint and meniscus kinematics were found between the prostheses and the native meniscus, and no effect on joint laxity was found. Level of Evidence: Level V.

Purpose: To reach consensus among international experts on a structured framework for standardized 3D leg alignment analysis based on 3D bone models, ensuring consistency and improving clinical applicability. Methods: A Delphi study was performed in four rounds. Rounds 1 and 2 involved a steering and rating group that developed statements based on principles preserving the 3D complexity of anatomical structures, identified through a systematic review. These statements encompassed approaches for deriving joint centres and joint orientations, and defining coordinate systems using 3D bone models. In Rounds 3 and 4, a panel of 35 international experts, including clinicians (54%) and engineers (46%), with participants from Europe (80%), Oceania (9%), Asia (6%), and the Americas (6%), evaluated these statements. Consensus was defined as ≥80% agreement. Results: Rounds 1 and 2 resulted in 31 statements to be included in the survey. Of these, 26 achieved consensus in Round 3, with the five remaining statements refined and reaching consensus in Round 4. Experts agreed on utilising all available relevant surface data to define joint centres, joint orientations, and individual femoral and tibial coordinate systems alongside a combined leg coordinate system, and adopting central 3D axes for femoral version and tibial torsion. Conclusions: This international Delphi consensus study provides a structured framework for a standardized 3D leg alignment analysis based on 3D bone models. This framework aims to enhance clinical applicability for preoperative planning and execution of uni‐ and multiplanar correction osteotomies around the knee, reduce the methodological variability in 3D leg alignment analysis literature, and improve cross‐study comparability. Level of Evidence: Level V.