Three-dimensional assessment of patellofemoral anatomy: Reliability and reference ranges.

BACKGROUND: Three-dimensional (3D) imaging and analysis offer new possibilities in preoperative diagnostics and surgical planning. Simultaneous 3D analysis of the joint angles and the patellofemoral anatomy allow for a realistic assessment of bony pathologies in patients with patellofemoral complaints. This study aims to develop a standardized and validated assessment of the 3D patellofemoral morphology and to establish reference ranges. METHODS: Thirteen patellofemoral anatomic landmarks were defined on 3D bone models of the lower limbs based on computer tomography data and evaluated regarding inter- and intra-observer variability. Further, 60 3D models of the lower limbs of young subjects without any previous knee operation/injury were assessed and rescaled reference values for relevant patellofemoral indices were obtained. RESULTS: The mean inter- and intra-observer deviation of all landmarks was below 2.3 mm. The interobserver intraclass correlation coefficient (ICC) was between 0.8 and 1.0 and the intra-observer ICC between 0.68 and 0.99 for all patellofemoral parameters. The calculated reference ranges are: Insall-Salvati index 1.0-1.4; patella tilt 6-18°; patella shift -4 to 3 mm; patella facet angle 118-131°; sulcus angle 141-156°; trochlear depth 3-6 mm; tibial-tuberosity to trochlear groove distance(TT-TG) 2D 14-21 mm; TT-TG 3D 11-18 mm; lateral trochlear inclination 13-23°; trochlear facet angle 43-65°. CONCLUSION: The demonstrated 3D analysis of the patellofemoral anatomy can be performed with high inter- and intra-observer correlation. Applying the obtained reference ranges and using existing 3D assessment tools for lower limb alignment, a preoperative 3D analysis and planning for complex knee procedures now is possible.

Three-dimensional assessment of lower limb alignment: Reference values and sex-related differences.

BACKGROUND: Three-dimensional (3D) preoperative planning and assisted surgery is increasingly popular in deformity surgery and arthroplasty. Reference ranges for 3D lower limb alignment are needed as a prerequisite for standardized analysis of alignment and preoperative planning in 3D, but are not yet established. METHODS: On 60 3D bone models of the lower limbs based on computed tomography data, fifteen parameters per leg were assessed by standardized validated 3D analysis. Distribution parameters and differences between sexes were evaluated. Reference values were generated by adding/subtracting one standard deviation from the mean. RESULTS: Women had a significantly lower mean mechanical lateral distal femoral angle compared with men (86.4 ±â€¯2.1° vs. 87.8 ±â€¯2.0°; P < .05) and significantly lower mean joint line convergence angle (-2.5 ±â€¯1.4° vs. -1.3 ±â€¯1.2; P < .01), but higher mean hip knee ankle angle (178.9 ±â€¯1.9° vs. 177.8 ±â€¯2.3°; P < .05) and mean femoral torsion (18.2 ±â€¯9.5° vs. 13.2 ±â€¯6.4°; P < .05), resulting in a tendency towards valgus alignment and vice versa for men. Differences in mean medial proximal tibial angle were not significant. The mean mechanical axis deviation from the tibial knee joint center was 6.9 ±â€¯7.3 mm medial and 1.4 ±â€¯16.1 mm ventral without significant differences between sexes. CONCLUSIONS: We describe total and sex-related reference ranges for all alignment relevant axes and joint angles of the lower limb. There are sex-related differences in certain alignment parameters, which should be considered in analysis and surgical planning.

Three-dimensional assessment of lower limb alignment: Accuracy and reliability.

INTRODUCTION: Three-dimensional (3D) surgical planning and patient-specific implants are becoming increasingly popular in orthopedics and trauma surgery. In contrast to the established and standardized alignment assessment on two-dimensional (2D) long standing radiographs (LSRs) there is neither a standardized nor a validated protocol for the analysis of 3D bone models of the lower limb. This study aimed to create a prerequisite for pre-operative planning. METHODS: According to 2D analysis and after meticulous research, 24 landmarks were defined on 3D bone models obtained from computed axial tomography (CT) scans for a 3D alignment assessment. Three observers with different experience levels performed the test three different times on three specimens. Intraobserver and interobserver variability of the landmarks and the intraclass correlation coefficient (ICC) of the resulting axes and joint angles were evaluated. RESULTS: Overall, the intraobserver and interobserver variability was low, with a mean deviation <5 mm for all landmarks. The ICC of all joint angles and axis deviations was >0.8, except for tibial torsion (ICC = 0.69). All knee joint angles showed excellent ICC (>0.95). CONCLUSIONS: Using the defined landmarks, a standardized 3D alignment assessment with low intraobserver and interobserver variability and high ICC values for the knee joint angles can be performed regardless of examiner's experience. The described method serves as a reliable standardized protocol for a 3D malalignment test of the lower limb. Three-dimensional pre-operative analysis might enhance understanding of deformities and lead to a new focus in surgical planning.

[Team training and assessment in mixed reality-based simulated operating room : Current state of research in the field of simulation in spine surgery exemplified by the ATMEOS project]. / Teamtraining und Assessment im Mixed-reality-basierten simulierten OP : Aktueller Stand der Forschung im Bereich Simulation in der Wirbelsäulenchirurgie am Beispiel des Projekts ATMEOS.

Surgical simulators are being increasingly used as an attractive alternative to clinical training in addition to conventional animal models and human specimens. Typically, surgical simulation technology is designed for the purpose of teaching technical surgical skills (so-called task trainers). Simulator training in surgery is therefore in general limited to the individual training of the surgeon and disregards the participation of the rest of the surgical team. The objective of the project Assessment and Training of Medical Experts based on Objective Standards (ATMEOS) is to develop an immersive simulated operating room environment that enables the training and assessment of multidisciplinary surgical teams under various conditions. Using a mixed reality approach, a synthetic patient model, real surgical instruments and radiation-free virtual X­ray imaging are combined into a simulation of spinal surgery. In previous research studies, the concept was evaluated in terms of realism, plausibility and immersiveness. In the current research, assessment measurements for technical and non-technical skills are developed and evaluated. The aim is to observe multidisciplinary surgical teams in the simulated operating room during minimally invasive spinal surgery and objectively assess the performance of the individual team members and the entire team. Moreover, the effectiveness of training methods and surgical techniques or success critical factors, e. g. management of crisis situations, can be captured and objectively assessed in the controlled environment.