Polyurethane Scaffold vs Fascia Lata Autograft for Hip Labral Reconstruction : Comparison of Femoroacetabular Biomechanics

The integrity of the acetabular labrum is critical in providing normal function and minimizing hip degeneration and is considered key for success in today's hip preservation algorithm. Many advances have been made in labral repair and reconstruction to restore the suction seal. To compare the biomechanical effects of segmental labral reconstruction between the synthetic polyurethane scaffold (PS) and fascia lata autograft (FLA). Our hypothesis was that reconstruction with a macroporous polyurethane implant and autograft reconstruction of fascia lata would normalize hip joint kinetics and restore the suction seal. Controlled laboratory study. Ten cadaveric hips from 5 fresh-frozen pelvises underwent biomechanical testing with a dynamic intra-articular pressure measurement system under 3 conditions: (1) intact labrum, (2) reconstruction with PS after a 3-cm segmental labrectomy, then (3) reconstruction with FLA. Contact area, contact pressure, and peak force were evaluated in 4 positions: 90º of flexion in neutral, 90º of flexion plus internal rotation, 90º of flexion plus external rotation, and 20º of extension. A labral seal test was performed for both reconstruction techniques. The relative change from the intact condition (value = 1) was determined for all conditions and positions. PS restored contact area to at least 96% of intact (≥0.96; range, 0.96-0.98) in all 4 positions, and FLA restored contact area to at least 97% (≥0.97; range, 0.97-1.19). Contact pressure was restored to ≥1.08 (range, 1.08-1.11) with the PS and ≥1.08 (range, 1.08-1.10) with the FLA technique. Peak force returned to ≥1.02 (range, 1.02-1.05) with PS and ≥1.02 (range, 1.02-1.07) with FLA. No significant differences were found between the reconstruction techniques in contact area in any position (P >.06), with the exception that FLA presented greater contact area in flexion plus internal rotation as compared with PS (P =.003). Suction seal was confirmed in 80% of PSs and 70% of FLAs (P = .62). Segmental hip labral reconstruction using PS and FLA reapproximated femoroacetabular contact biomechanics close to the intact state. These findings provide preclinical evidence supporting the use of a synthetic scaffold as an alternative to FLA and therefore avoiding donor site morbidity

Failure of human rhombic lip differentiation underlies medulloblastoma formation

Medulloblastoma (MB) comprises a group of heterogeneous paediatric embryonal neoplasms of the hindbrain with strong links to early development of the hindbrain 1–4. Mutations that activate Sonic hedgehog signalling lead to Sonic hedgehog MB in the upper rhombic lip (RL) granule cell lineage 5–8. By contrast, mutations that activate WNT signalling lead to WNT MB in the lower RL 9,10. However, little is known about the more commonly occurring group 4 (G4) MB, which is thought to arise in the unipolar brush cell lineage 3,4. Here we demonstrate that somatic mutations that cause G4 MB converge on the core binding factor alpha (CBFA) complex and mutually exclusive alterations that affect CBFA2T2, CBFA2T3, PRDM6, UTX and OTX2. CBFA2T2 is expressed early in the progenitor cells of the cerebellar RL subventricular zone in Homo sapiens, and G4 MB transcriptionally resembles these progenitors but are stalled in developmental time. Knockdown of OTX2 in model systems relieves this differentiation blockade, which allows MB cells to spontaneously proceed along normal developmental differentiation trajectories. The specific nature of the split human RL, which is destined to generate most of the neurons in the human brain, and its high level of susceptible EOMES +KI67 + unipolar brush cell progenitor cells probably predisposes our species to the development of G4 MB

Strategies used to manage overlap of primary study data by exercise-related overviews: protocol for a systematic methodological review

Introduction One of the most conflicting methodological issues when conducting an overview is the overlap of primary studies across systematic reviews (SRs). Overlap in the pooled effect estimates across SRs may lead to overly precise effect estimates in the overview. SRs that focus on exercise-related interventions are often included in overviews aimed at grouping and determining the effectiveness of various interventions for managing specific health conditions. The aim of this systematic methodological review is to describe the strategies used by authors of overviews focusing on exercise-related interventions to manage the overlap of primary studies.Methods and analysis A comprehensive search strategy has been developed for different databases and their platforms. The databases to be consulted will be MEDLINE (Ovid), Embase (Ovid), The Cochrane Database of Systematic Reviews (Cochrane Library) and Epistemonikos. Two reviewers will independently screen the records identified through the search strategy and extract the information from the included overviews. The frequency and the type of overlap management strategies of the primary studies included in the SRs will be considered as the main outcome. In addition, the recognition of the lack of use of any overlap management strategy and the congruence between planning and conducting the overview focusing on overlap management strategies will be assessed. A subgroup analysis will be carried out according to the journal impact factor, year of publication and compliance with the Preferred Reporting Items for Overviews of Reviews statement.Ethics and dissemination This study will not involve human subjects and therefore does not require ethics committee approval. However, the conduct and reporting of the findings of this review will be conducted in a rigorous, systematic and transparent manner, which relates to research ethics.The findings of this review will be presented at scientific conferences and published as one or more studies in peer-review scientific journals related to rehabilitation or research methods

Hip labral reconstruction with a polyurethane scaffold: Restoration of femoroacetabular contact biomechanics

Background: Many advances have been made in hip labral repair and reconstruction and in the restoration of the suction seal. Purpose/hypothesis: The purpose of this study was to evaluate the biomechanical effects of segmental labral reconstruction with a synthetic polyurethane scaffold (PS) in comparison with segmental labrectomy. Our hypothesis was that reconstruction with a icroporous polyurethane implant would normalize joint kinetics of the hip and restore the suction seal. Study design: Controlled laboratory study. Methods: We used 10 hips from 5 fresh-frozen pelvises with an intact acetabular labrum without osteoarthritis. Using an intra-articular pressure measurement system, the contact area, contact pressure, and peak force were assessed for the following conditions: intact labrum, partial anterosuperior labrectomy, and PS reconstruction. For each condition, all specimens were analyzed in 4 positions (90° of flexion, 90° of flexion and internal rotation, 90° of flexion and external rotation, and 20° of extension) and underwent a labral seal test. The relative change from the intact condition was determined for all conditions and positions. Results: Compared with the intact labrum, labrectomy resulted in a significant decrease in the contact area (P .05), whereas the contact pressure was significantly decreased compared with labrectomy (P < .05) but did not return to normal values. The labral seal was lost in all specimens after labrectomy but was restored in 80% of the specimens after PS reconstruction. Conclusion: Femoroacetabular contact biomechanics significantly worsened after partial labrectomy; reconstruction using a PS restored the contact area and peak force to the intact state and improved the contact pressure increases seen after partial labrectomy. The contact area and peak force were normalized, and the labral seal was re-established in most cases. Clinical relevance: This study provides biomechanical evidence for the use of a scaffold for labral reconstruction