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Introduction: The objective of this investigation was to compare different techniques to improve visualization and reduction in tibial plateau fractures involving the central lateral segments. Methods: Matched pairs of pre-fractured cadaveric tibial plateau fractures that include the central lateral segments were treated by either an anterolateral approach (supine) or PL approach (prone). Reduction was stepwise extended by additional fracturoscopy (FS), nanoscopy (NS) and lastly by epicondyle osteotomy (ECO). Reduction was analyzed by 3D scan and visualization of the lateral plateau was quantified. Results: Ten specimens (3 pairs 41B3.1, 2 pairs 41C3.3) were analyzed. Fracture steps involving the antero-latero-central (ALC) segment were insufficiently reduced after fluoroscopy using both approaches (AL 2.2 ± 1.2 mm vs PL 2.2 ± 1.0 mm, p 0.95). Additional NS and ECO achieved optimized fracture reduction in the ALC segment (NS AL 1.6 ± 1.3 mm vs PL 0.8 ± 0.9 mm, p 0.32). NS provided visualization of the entire lateral plateau (PL 102.9% ± 7.4, AL 108.8 ± 19.2%), while fracturoscopy only allowed visualization of the ALL segment and partially of PLL and ALC segments (PL 22.0 ± 23.4%, AL 29.7 ± 18.3%). Conclusion: Optimized reduction of tibial head fractures with involvement of latero-central segments requires additional video-assisted reduction or extended approaches. Nanoscopy helps visualizing of the entire lateral plateau, when compared to fracturoscopy and may become a valuable reduction aid. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this study was to compare the reduction quality of the anterolateral (AL) and modified posterolateral approach (PL) in lateral tibial plateau fractures involving the posterior column and central segments. Methods: Matched pairs of pre-fractured cadaveric tibial plateau fractures were treated by either AL approach (supine position) or PL approach (prone position). Reduction was controlled by fluoroscopy and evaluated as satisfying or unacceptable. Afterwards, the reduction was examined by 3D scan. Results: 10 specimens (3 pairs 41B3.1, 2 pairs 41C3.3) were evaluated. PL approach achieved significantly (p 0.00472) better fracture reduction results (0.4 ± 0.7 mm) of the posterior column compared to the AL group (2.1 ± 1.4 mm). Fracture steps involving the central area of the lateral plateau were insufficiently reduced after fluoroscopy using both approaches. Conclusion: Optimal reduction of displaced tibial plateau fractures involving the posterolateral column necessitates a posterior approach, which can be conducted in prone or lateral positioning. The anterolateral approach is indicated in fractures with minor displacement of the posterolateral rim but fracture extension in the latero-central segments. In these cases, an additional video-assisted reduction or extended approaches are helpful. [ABSTRACT FROM AUTHOR]

Background: The purpose of the study was to investigate and describe neurovascular complications and mid-term clinical outcomes of operatively managed fractures of the distal humerus in a paediatric population. Neurovascular injuries are common in these fractures, but reports about their implications for mid-term clinical outcomes is sparse. Methods: A single-centre retrospective study was conducted at a university teaching hospital investigating paediatric patients who underwent operative management of a distal humerus fracture between 2014 and 2018. Patient demographics, fracture classification, pre-, peri- and postoperative neurovascular complications were investigated. Mid-term follow up clinical examination and functional scoring using QuickDASH, the Broberg and Morrey Score (BMS), the Mayo Elbow Performance Score (MEPS) and the Numeric Rating Scale were performed. Results: A total of 84 patients were identified, of which 34 met the inclusion criteria and were available for follow-up clinical examination. The average time to follow-up was 150 weeks (1049.44 days ± 448.54). Ten primary traumatic neurovascular complications were identified, the majority of which involved the median nerve. Primary traumatic dissection of the brachial artery was recorded in three patients. Secondary iatrogenic nerve injury was documented in five patients after previously normal clinical examination. At follow-up, the average QuickDASH score was 3.0 ± 4.3, BMS was 98.6 ± 3.4 and MEPS was 97.1 ± 3.3 points. Conclusions: The mid-term clinical outcome following surgical management of distal humerus fractures is excellent. There is, however, a considerable frequency of both primary and secondary neurovascular complications, which must be considered when opting to treat these injuries surgically. [ABSTRACT FROM AUTHOR]

Background: Both the superficial medial collateral ligament (sMCL) and the deep MCL (dMCL) contribute to the restraint of anteromedial (AM) rotatory instability (AMRI). Previous studies have not investigated how MCL reconstructions control AMRI. Purpose/Hypothesis: The purpose was to establish the optimal medial reconstruction for restoring normal knee kinematics in an sMCL- and dMCL-deficient knee. It was hypothesized that AMRI would be better controlled with the addition of an anatomically shaped (flat) sMCL reconstruction and with the addition of an AM reconstruction replicating the function of the dMCL. Study Design: Controlled laboratory study. Methods: A 6 degrees of freedom robotic system equipped with a force-torque sensor was used to test 8 unpaired knees in the intact, sMCL/dMCL sectioned, and reconstructed states. Four different reconstructions were assessed. The sMCL was reconstructed with either a single-bundle (SB) or a flattened hamstring graft aimed at better replicating the appearance of the native ligament. These reconstructions were tested with and without an additional AM reconstruction. Simulated laxity tests were performed at 0°, 30°, 60°, and 90° of flexion: 10 N·m valgus rotation, 5 N·m internal and external rotation (ER), and an AM drawer test (combined 134-N anterior tibial drawer in 5 N·m ER). The primary outcome measures of this force-controlled setup were anterior tibial translation (ATT; in mm) and axial tibial rotation (in degrees). Results: Sectioning the sMCL/dMCL increased valgus rotation, ER, and ATT with the simulated AM draw test at all flexion angles. SB sMCL reconstruction was unable to restore ATT, valgus rotation, and ER at 30°, 60°, and 90° of flexion to the intact state (P <.05). Flat MCL reconstruction restored valgus rotation at all flexion angles to the intact state (P >.05). ER was restored at all angles except at 90°, but ATT laxity in response to the AM drawer persisted. Addition of an AM reconstruction improved control of ATT relative to the intact state at all flexion angles (P >.05). Combined flat MCL and AM reconstruction restored knee kinematics closest to the intact state. Conclusion: In a cadaveric model, AMRI resulting from an injured sMCL and dMCL complex could not be restored by an isolated SB sMCL reconstruction. A flat MCL reconstruction or an additional AM procedure, however, better restored medial knee stability. Clinical Relevance: In patients evaluated with a combined valgus and AM rotatory instability, a flat sMCL and an additional AM reconstruction may be superior to an isolated SB sMCL reconstruction. [ABSTRACT FROM AUTHOR]

Background: The treatment of osteochondral defects (OCDs) constitutes a major problem for orthopaedic surgeons. The altered mechanics and the cell types, with associated soluble factors derived from the exposed subchondral bone, are likely responsible for the mechanically and structurally inferior articular cartilage subsequently obtained as a repair tissue. There is therefore an unmet clinical need for bioresponsive biomaterials that allow cell delivery, reduce cell infiltration from the bone marrow, and support chondrogenesis in the presence of joint mechanical loading. Purpose: To develop a cell-laden injectable biomaterial, with bioadhesive properties, low cell invasion, and good mechanoresilience, in which simulated joint loading could induce tissue maturation through the production and activation of transforming growth factor beta 1 (TGF-β1). Study Design: Controlled laboratory study. Methods: Human bone marrow–derived mesenchymal stromal/stem cells were encapsulated in tyramine-modified hyaluronic acid (HA-Tyr) hydrogels, with crosslinking initiated by the addition of horseradish peroxidase (HRP) and various concentrations of hydrogen peroxide (H2O2; 0.3-2 mM). Cytocompatibility and biomechanical and adhesive properties were analyzed by live/dead staining, rheology, and push-out test, respectively. For multiaxial loading, cell-laden hydrogels were subjected to 10% compression superimposed onto a 0.5-N preload and shear loading (±25°) at 1 Hz for 1 hour per day and 5 times a week for 4 weeks. TGF-β1 production and activation were measured by enzyme-linked immunosorbent assay (ELISA). Results: The viscoelastic properties of the cell-laden HA-Tyr hydrogels, as crosslinked with different ratios of HRP and H2O2, were demonstrated for a range of cell densities and HRP/H2O2 concentrations. In the absence of serum supplementation, cell invasion into HA-Tyr hydrogels was minimal to absent. The bonding strength of HA-Tyr to articular cartilage compared favorably with clinically used fibrin gel. Conclusion: HA-Tyr hydrogels can be mechanically conditioned to induce activation of endogenous TGF-b1 produced by the embedded cells. HA-Tyr hydrogels function as cell carriers supporting biomechanically induced production and activation of TGF-β1 and as bioadhesive materials with low cell invasion, suggesting that they hold promise as a novel biomaterial for OCD repair strategies. Clinical Relevance: Leveraging physiological joint mechanics to support chondrogenic graft maturation in an optimized mechanosensitive hydrogel in the absence of exogenous growth factors is of highest interest for OCD repair. [ABSTRACT FROM AUTHOR]