Dimensional accuracy and precision and surgeon perception of additively manufactured bone models: effect of manufacturing technology and part orientation.

BACKGROUND: Additively manufactured (AM) anatomical bone models are primarily utilized for training and preoperative planning purposes. As such, they must meet stringent requirements, with dimensional accuracy being of utmost importance. This study aimed to evaluate the precision and accuracy of anatomical bone models manufactured using three different AM technologies: digital light processing (DLP), fused deposition modeling (FDM), and PolyJetting (PJ), built in three different part orientations. Additionally, the study sought to assess surgeons' perceptions of how well these models mimic real bones in simulated osteosynthesis. METHODS: Computer-aided design (CAD) models of six human radii were generated from computed tomography (CT) imaging data. Anatomical models were then manufactured using the three aforementioned technologies and in three different part orientations. The surfaces of all models were 3D-scanned and compared with the original CAD models. Furthermore, an anatomical model of a proximal femur including a metastatic lesion was manufactured using the three technologies, followed by (mock) osteosynthesis performed by six surgeons on each type of model. The surgeons' perceptions of the quality and haptic properties of each model were assessed using a questionnaire. RESULTS: The mean dimensional deviations from the original CAD model ranged between 0.00 and 0.13 mm with maximal inaccuracies < 1 mm for all models. In surgical simulation, PJ models achieved the highest total score on a 5-point Likert scale ranging from 1 to 5 (with 1 and 5 representing the lowest and highest level of agreement, respectively), (3.74 ± 0.99) in the surgeons' perception assessment, followed by DLP (3.41 ± 0.99) and FDM (2.43 ± 1.02). Notably, FDM was perceived as unsuitable for surgical simulation, as the material melted during drilling and sawing. CONCLUSIONS: In conclusion, the choice of technology and part orientation significantly influenced the accuracy and precision of additively manufactured bone models. However, all anatomical models showed satisfying accuracies and precisions, independent of the AM technology or part orientation. The anatomical and functional performance of FDM models was rated by surgeons as poor.

Gelatin methacryloyl as environment for chondrocytes and cell delivery to superficial cartilage defects.

Cartilage damage typically starts at its surface, either due to wear or trauma. Treatment of these superficial defects is important in preventing degradation and osteoarthritis. Biomaterials currently used for deep cartilage defects lack appropriate properties for this application. Therefore, we investigated photo-crosslinked gelatin methacryloyl (gelMA) as a candidate for treatment of surface defects. It allows for liquid application, filling of surface defects and forming a protective layer after UV-crosslinking, thereby keeping therapeutic cells in place. gelMA and photo-initiator lithium phenyl-2,4,6-trimethyl-benzoylphosphinate (Li-TPO) concentration were optimized for application as a carrier to create a favorable environment for human articular chondrocytes (hAC). Primary hAC were used in passages 3 and 5, encapsulated into two different gelMA concentrations (7.5 wt% (soft) and 10 wt% (stiff)) and cultivated for 3 weeks with TGF-ß3 (0, 1 and 10 ng/mL). Higher TGF-ß3 concentrations induced spherical cell morphology independent of gelMA stiffness, while low TGF-ß3 concentrations only induced rounded morphology in stiff gelMA. Gene expression did not vary across gel stiffnesses. As a functional model gelMA was loaded with two different cell types (hAC and/or human adipose-derived stem cells [ASC/TERT1]) and applied to human osteochondral osteoarthritic plugs. GelMA attached to the cartilage, smoothened the surface and retained cells in place. Resistance against shear forces was tested using a tribometer, simulating normal human gait and revealing maintained cell viability. In conclusion gelMA is a versatile, biocompatible material with good bonding capabilities to cartilage matrix, allowing sealing and smoothening of superficial cartilage defects while simultaneously delivering therapeutic cells for tissue regeneration.

Standard radiographic assessments of distal radius fractures miss involvement of the distal radioulnar joint: a diagnostic study.

INTRODUCTION: Distal radius fractures account for one-fifth of all fractures in the emergency department. Their classification based on standard radiographs is common practice although low inter-observer reliabilities and superiority of computer tomography (CT) scanning in evaluation of joint congruency have been reported. MATERIALS AND METHODS: We retrospectively analyzed 96 displaced distal radius fractures scheduled for open reduction and internal fixation using standard radiographic assessment. The radiographs were classified with the Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA), Fernandez and Frykman classifications by three observers and inter-rater reliabilities were calculated. Additional CT scanning was performed in all cases and the following parameters were assessed: radiocarpal joint involvement, fracture extent into the radial sigmoid notch, i.e. the distal radio-ulnar joint, comminution of the metaphysis, and concomitant ulnar styloid fracture. The CT scans were used as a reference standard to determine sensitivity and accuracy of standard radiographic assessment in evaluation of distal radius fractures. RESULTS: The inter-rater agreement for the AO classification was 35.4%, 68.8% for the Fernandez and 38.5% for the Frykman classification. Fracture extension into the radiocarpal joint was present in 81 cases (84.4%). Sigmoid notch involvement was found in 81 fractures (84.4%). Involvement of both joints was present in 72 cases (75%). The sensitivity of standard radiographs regarding radiocarpal joint involvement was 93.8%. Considering involvement of the distal radio-ulnar joint the false-negative rate using standard radiographs was 61.7% and the test's accuracy for sigmoid notch involvement was 45.8%. CONCLUSION: This study demonstrates that involvement of the sigmoid notch is frequently missed in standard radiographs. The presented data support the frequent use of CT imaging to allow the holistic illustration of a fracture's complexion and to ensure optimal pre-operative planning.

Does patient positioning influence blood loss and transfusion rate in hip replacement for femoral neck fractures? A single-centre, retrospective chart review.

BACKGROUND: We compared blood loss and transfusion frequency between the lateral decubitus and the supine position in patients undergoing hip replacement surgery due to femoral neck fractures. METHODS: We retrospectively included femoral neck fracture patients treated with either hemi (HA) or total hip arthroplasty (THA). We included a total of 626 patients, of which 313 patients underwent surgery in the lateral decubitus position and 313 patients in the supine position. Preoperative and day 1 postoperative blood measures including hemoglobin (Hb), hematocrit (Hct), and red blood cell count (RBC) were evaluated, as well as transfusion records analyzed. RESULTS: The following decrease of laboratory parameters between pre- and 1st day postoperative measures was noted: RBC: -0.77 G/L (± 0.5 G/L, median = -0.80 G/L; range: -0.50 - -1.10 G/L); Hct: -7.08 % (± 4.7 %, range: -4.70 - -9.90 G/L); Hb: -2.36 g/dL (± 1.6 g/dL, range: -1.50. - -3.40 g/dL). We did not observe significant differences in transfusion frequency between the two study cohorts (p = 0.735 for THA, p = 0.273 for HA). No influence of patient positioning on Hb-decrease, Hct-decrease, or RBC-decrease was noted in our two-way ANOVA models with consideration of implant type and fixation technique (F(3,618) = 1.838, p = 0.139; F(3,618) = 2.606, p = 0.051; F(3,618) = 1.407, p = 0.240). CONCLUSIONS: We did not observe  significant differences in perioperative blood values and transfusion rates in association with patient positioning in patients undergoing hip replacement surgery for femoral neck fractures. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Relationship between the Thickness of the Coracoid Process and Latarjet Graft Positioning-An Anatomical Study on 70 Embalmed Scapulae.

BACKGROUND: The Latarjet procedure is a popular technique with the aim of the reconstruction of glenoid cavity bone defects in patients with chronic anterior shoulder instability. Studies have shown that the Congruent arc Latarjet procedure is better able to reconstruct larger defects than the Classic Latarjet, but there is a lack of information on the limitations of both methods. METHODS: The dimensions of the glenoid width and the native coracoid process of two groups with 35 Formol-Carbol embalmed scapulae each were measured using a digital caliper. The relationship between the coracoid graft and the anterior-posterior diameter of the glenoid cavity was calculated to determine the maximum defect size of the glenoid cavity width, which can be treated by both Latarjet techniques. RESULTS: The average restorable defect size of the anterior segment of the glenoid cavity was 28.4% ± 4.6% (range 19.2%-38.8%) in the Classic Latarjet group, and 45.6% ± 5.2% (range 35.7%-57.1%) in the Congruent arc Latarjet group. Based on our results, the feasibility of the Classic Latarjet procedure to reconstitute the anatomical width of the glenoid cavity was 86% in a 25% bone loss scenario, and only 40% in a 30% bone loss scenario. CONCLUSION: Based on our results we are unable to define a clear threshold for the optimal Latarjet graft position. In glenoid cavity defects <20%, the Classic Latarjet technique usually provides enough bone stock for anatomical reconstruction. Defects ≥35% of the glenoid cavity width should only be treated with a coracoid graft in the Congruent arc position. In the critical area between 20% and 35% of bone loss, we suggest the preoperative assessment of coracoid dimensions, based on which the graft position can be planned to restore the anatomical anterior-posterior diameter of the glenoid cavity.

Brazilin blocks catabolic processes in human osteoarthritic chondrocytes via inhibition of NFKB1/p50.

This study aimed to evaluate the chondroprotective and anti-inflammatory activity of brazilin in human osteoarthritic (OA) cartilage and chondrocytes with particular focus on the nuclear factor-kappa B (NF-κB) pathway. Therefore, brazilin was isolated from Caesalpinia sappan and identified using high performance liquid chromatography (HPLC). The effect of brazilin was assessed in cartilage explants treated with 10 ng/ml interleukin (IL)-1ß and 10 ng/ml tumor necrosis factor (TNF)-α using histological and biochemical glycosaminoglycan (GAG) analyses and in primary chondrocytes treated with 10 ng/ml IL-1ß using RT-qPCR, ELISA, and Western blot. The involvement of NF-κB signaling was examined using a human NF-κB signaling array and in silico pathway analysis. Brazilin was found to reduce the GAG loss from cartilage explants stimulated with IL-1ß and TNF-α. NF-κB pathway analysis in chondrocytes revealed NFKB1/p50 as a central player regulating the anti-inflammatory activities of brazilin. Brazilin suppressed the IL-1ß-mediated up-regulation of OA markers and the induction of NFKB1/p50 in chondrocytes. In conclusion, brazilin effectively attenuates catabolic processes in human OA cartilage and chondrocytes-at least in part due to the inhibition of NFKB1/p50-which indicates a chondroprotective potential of brazilin in OA. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2431-2438, 2018.