Purpose: To evaluate the association of acromial morphology and subacromial impingement. Methods: Bilateral shoulder computed tomography was performed in 138 patients who received shoulder arthroscopy. Measured parameters included: acromial tilt (AT), modified acromial tilt (mAT), acromial slope (AS), acromiohumeral interval (AHI), lateral acromial angle (LAA), acromial index (AI), critical shoulder angle (CSA), acromial anterior protrusion (AAP), and acromial inferior protrusion (AIP). Acromial morphological characteristics were compared between groups. Side-to-side differences were assessed between affected and non-affected shoulders. Intra- and inter-observer agreements for each parameter were calculated. Results: AT (25.90 vs. 29.41°), mAT (18.88 vs. 22.64°), and AHI (5.46 vs. 6.47 mm) were significantly smaller in impinged patients. The impingement group demonstrated significantly larger AI (63.50 vs. 59.84%), CSA (31.78 vs. 28.74°), AAP (7.13 vs. 5.32 mm), and AIP (5.51 vs. 4.04 mm). Regarding side-to-side comparison, the acromial morphology was significantly different between the affected and non-affected shoulders in impinged patients, while the difference was slight and insignificant in control patients. All, except AS and LAA, measured parameters demonstrated good intra- and inter-observer agreements. Conclusions: Three-dimensional reconstructed CT scan is a reliable method to measure shoulder morphology. The acromial morphological variation is related with sub acromial impingement, however, the causal relationship of them should be further explored.

Background: High-intensity interval training (HIIT) reportedly improves bone metabolism and increases bone mineral density (BMD). The purpose of the present study was to investigate whether lactate mediates the beneficial effects of exercise on BMD, bone microarchitecture, and biomechanical properties in an established osteoporotic animal model. In addition, we hypothesized that lactate-induced bone augmentation is achieved through enhanced osteoblast differentiation and mineralization. Methods: A total of 50 female C57BL/6 mice were randomly allocated into 5 groups: the nonovariectomized group, the ovariectomized group (OVX), the HIIT group (OVX + HIIT), the HIIT with lactate transporter inhibition group (OVX + HIIT + INH), and the lactate subcutaneous injection group (OVX + LAC). After 7 weeks of intervention, bone mass, bone strength, and bone formation/resorption processes were evaluated via microcomputed tomography (micro-CT), biomechanical testing, histological analysis, and serum biochemical assays; in vitro studies were performed to explore the bone anabolic effect of lactate at the cellular level. Results: Micro-CT revealed significantly increased BMD in both the OVX + HIIT group (mean difference, 41.03 mg hydroxyapatite [HA]/cm³ [95% CI, 2.51 to 79.54 mg HA/cm³]; p = 0.029) and the OVX + LAC group (mean difference, 40.40 mg HA/cm³ [95% CI, 4.08 to 76.71 mg HA/cm³]; p = 0.031) compared with the OVX group. Biomechanical testing demonstrated significantly improved mechanical properties in those 2 groups. However, the beneficial effects of exercise on bone microstructure and biomechanics were largely abolished by blocking the lactate transporter. Notably, histological and biochemical results indicated that increased bone formation was responsible for the bone augmentation effects of HIIT and lactate. Cell culture studies showed a marked increase in the expression of osteoblastic markers with lactate treatment, which could be eliminated by blocking the lactate transporter. Conclusions: Lactate may have mediated the bone anabolic effect of HIIT in osteoporotic mice, which may have resulted from enhanced osteoblast differentiation and mineralization. Clinical Relevance: Lactate may mediate the bone anabolic effect of HIIT and serve as a potential inexpensive therapeutic strategy for bone augmentation.

Osteochondral (OC) defects cannot adequately repair themselves due to their sophisticated layered structure and lack of blood supply in cartilage. Although therapeutic interventions are reaching an advanced stage, current clinical therapies to repair defects are in their infancy. Among the possible therapies, OC tissue engineering has shown considerable promise, and multiple approaches utilizing scaffolds, cells, and bioactive factors have been pursued. The most recent trend in OC tissue engineering has been to design gradient scaffolds using different materials and construction strategies (such as bi-layered, multi-layered, and continuous gradient structures) to mimic the physiological and mechanical properties of OC tissues while further enabling OC repair. This review focuses specifically on design and construction strategies for gradient scaffolds and their role in the successful engineering of OC tissues. The current dilemmas in the field of OC defect repair and the efforts of tissue engineering to address these challenges were reviewed. In addition, the advantages and limitations of the typical fabrication techniques for gradient scaffolds were discussed, with examples of recent studies summarizing the future prospects for integrated gradient scaffold construction. This updated and enlightening review could provide insights into our current understanding of gradient scaffolds in OC tissue engineering.