Stab lesion of the L4/L5 intervertebral disc in the rat causes acute changes in disc bending mechanics.

Low-back pain often coincides with altered neuromuscular control, possibly due to changes in spine stability resulting from injury or degeneration, or due to effects of nociception. The relative importance of these mechanisms, and their possible interaction, are unknown. In spine bending, the bulk of the load is borne by the IVD, yet the acute effects of intervertebral disc (IVD) injury on bending mechanics have not been investigated. In the present study, we aimed to quantify the acute effects of a stab lesion of the disc on its mechanical properties, because such changes can be expected to elicit compensatory changes in neuromuscular control. L4/L5 spinal segments were collected from 27 Wistar rats within two hours after sacrifice and stored at -20℃. Following thawing, bending tests were performed to assess the intersegmental angle-moment characteristics. Specimens were loaded in right bending, left bending and flexion, before and after a stab lesion of the IVD fully penetrating the nucleus pulposus. In the angle-moment curves, we found reduced moments at equal bending angles after IVD lesion in left bending, right bending and flexion. Peak stiffness, peak moment, and hysteresis were significantly decreased (by 7.8-27.7 %) after IVD lesion in all directions. In conclusion, L4/L5 IVD lesion in the rat caused small to moderate acute changes in IVD mechanical properties. Our next steps will be to evaluate the longer term effects of IVD lesion on spine mechanics and the neural control of trunk muscles.

Creation of a decellularized vaginal matrix from healthy human vaginal tissue for potential vagina reconstruction: experimental studies.

BACKGROUND: When a disorder causes the absence of a healthy, full-size vagina, various neovaginal creation methods are available. Sometimes dilation or stretching of the vaginal cavity is sufficient, but intestinal or dermal flap tissue is generally required. However, different inherent tissue properties cause complications. Therefore, a lost body part should be replaced with a similar material. The use of organ-specific acellular vaginal tissue carries great potential, as its similar architecture and matrix composition make it suitable for vaginal regeneration. METHODS: The authors developed an optimized protocol for decellularization of healthy human vaginal tissue. Resected colpectomy tissue from 12 healthy transgender patients was used. Successful decellularization was confirmed by applying acellular criteria from in-vivo remodeling reports. Suitability as a tissue-mimicking scaffold for vaginal reconstruction was determined by visible structural features, biocompatibility during stretching, and the presence of visible collagen, elastin, laminin, and fibronectin. RESULTS: Histological examination confirmed the preservation of structural features, and minimal cellular residue was seen during fluorescence microscopy, DNA and RNA quantification, and fragment length examination. Biomechanical testing showed decreased peak load (55%, P <0.05), strain at rupture (23%, P <0.01), and ultimate tensile stress (55%, P <0.05) after decellularization, while the elastic modulus (68%) did not decrease significantly. Fluorescence microscopy revealed preserved Fibronectin-I/II/III and Laminin-I/II, while Collagen-I and Ficolin-2B were decreased but mostly retained. CONCLUSIONS: The absence of cellular residue, moderately altered biomechanical extracellular matrix properties, and mostly preserved structural proteins appear to make our decellularized human vaginal matrix a suitable tissue-mimicking scaffold for vagina transplantation when tissue survival through vascularization and innervation are accomplished in the future.

Chronic non-specific low back pain and ankle proprioceptive acuity in community-dwelling older adults.

BACKGROUND: For people above 65 years old, low-back pain (LBP) is associated with balance problems and falls. Down-weighting of proprioception due to ageing and LBP may cause such balance problems. While lumbar proprioceptive deficits have been shown in LBP and indications for more generalized deficits have been found, ankle proprioception, which is crucial for balance control, has not been studied in people with LBP. RESEARCH QUESTION: Is there any difference in ankle proprioceptive acuity between community-dwelling older adults with and without LBP? We hypothesized that ankle proprioception was impaired in community-dwelling older adults with LBP compared to those without LBP. METHODS: Thirty participants over 65 years old volunteered. Fifteen had LBP (M/F = 2/13, age = 72.0 (4.6) years), fifteen were healthy controls without back pain (control group) (M/F = 2/13, age = 72.1 (4.8) years). Ankle proprioception was measured in normal weight-bearing conditions, using the Active Movement Extent Discrimination Apparatus (AMEDA). Accuracy on the ankle proprioceptive test was expressed as absolute error (AE), constant error (CE) and variable error (VE). RESULTS: AE was significantly larger (P = 0.029, 95 % CI = [0.00, 0.90]) in the LBP group, CE was also significantly larger (P = 0.046, 95 % CI = [-0.91, -0.01]), indicating an underestimation of ankle inversion in participants with LBP compared to controls. VE was not different between the two groups (P = 0.520, 95 % CI = [-0.20, 0.59]). No significant correlation was found between pain intensity and AE, CE or VE (P > 0.05). CONCLUSION: Ankle proprioception decreased in older people with LBP compared to healthy peers, suggesting impaired central proprioceptive processing. Older people with LBP underestimate the extent of ankle inversion, which may increase fall risk. Thus, evaluation and training of ankle proprioception may be useful in older people with LBP.