Using cross-linked hyaluronic acid gel to prevent postoperative lumbar epidural space adhesion: in vitro and in vivo studies

A low-swelling hydrogel as a multirole sealant for efficient dural defect sealing and prevention of postoperative adhesion

Dural defects and subsequent complications, including cerebrospinal fluid (CSF) leakage, are common in both spine surgery and neurosurgery, and existing clinical treatments are still unsatisfactory. In this study, a tissue-adhesive and low-swelling hydrogel sealant comprising gelatin and o-phthalaldehyde (OPA)-terminated 4-armed poly(ethylene glycol) (4aPEG-OPA) is developed via the OPA/amine condensation reaction. The hydrogel shows an adhesive strength of 79.9 ± 12.0 kPa on porcine casing and a burst pressure of 208.0 ± 38.0 cmH2O. The hydrogel exhibits a low swelling ratio at physiological conditions, avoiding nerve compression in the limited spinal and intracranial spaces. In rat and rabbit models of lumbar and cerebral dural defects, the 4aPEG-OPA/gelatin hydrogel achieves excellent performance in dural defect sealing and preventing CSF leakage. Moreover, local inflammation, epidural fibrosis and postoperative adhesion in the defect areas are markedly reduced. Thus, these findings establish the strong potential of the hydrogel sealant for the effective watertight closure of dural defects.

Advanced postoperative tissue antiadhesive membranes enabled with electrospun nanofibers

Tissue adhesion is one of the most common postoperative complications, which is frequently accompanied by inflammation, pain, and even dyskinesia, significantly reducing the quality of life of patients. Thus, to prevent the formation of tissue adhesions, various strategies have been explored. Among these methods, placing anti-adhesion membranes over the injured site to separate the wound from surrounding tissues is a simple and prominently favored method. Recently, electrospun nanofibers have been the most frequently investigated antiadhesive membranes due to their tunable porous structure and high porosities. They not only can act as an essential barrier and functional carrier system but also allow for high permeability and nutrient transport, showing great potential for preventing tissue adhesion. Herein, we provide a short review of the most recent applications of electrospun nanofibrous antiadhesive membranes in tendons, the abdominal cavity, dural sac, pericardium, and meninges. Firstly, each section highlights the most representative examples and they are sorted based on the latest progress of related research. Moreover, the design principles, preparation strategies, overall performances, and existing problems are highlighted and evaluated. Finally, the current challenges and several future ways to develop electrospun nanofibrous antiadhesive membranes are proposed. The systematic discussion and proposed directions can shed light on ideas and guide the reasonable design of electrospun nanofibrous membranes, contributing to the development of exceptional tissue anti-adhesive materials in the foreseeable future.

Safety of Epidural Hyaluronic Acid Injections in Managing the Symptoms of Lumbar Foraminal Stenosis: A Prospective Preliminary Study

Lumbar foraminal stenosis (LFS) of degenerative origin is a common reason for distorted neurodynamics of nerve roots, causing radicular pain that is difficult to resolve with conservative treatments. A hyaluronic acid (HA), providing a sliding layer in the mechanical interface of a nerve root in a narrowed lateral recess, could potentially improve its neurodynamics and the trophic, leading to radicular pain reduction and improvement of function. This study aimed to assess the usefulness of ultrasound-guided HA epidural injections combined with neuromobilization in the conservative treatment of LFS. A group of 10 consecutively admitted patients with MRI-confirmed LFS and reduced straight leg raise (SLR) test results were qualified for a single HA epidural injection along with self-performed neuromobilization. Three measurement tools were used for primary outcomes: the numeric rating scale (NRS) for pain intensity, the Oswestry disability index (ODI) and the Roland-Morris questionnaire (RMQ) for disability level, and the angle of pain-free elevation in the SLR test as a functional assessment. The treatment was accomplished in all patients (100%). Overall, 60% of the patients completed all follow-up visits. There were no statistically significant differences regarding the results of the NRS, ODI, or RMQ; however, a statistically significant increase in the results of the SLR test was noted (p = 0.015). Three patients reported a flare-up of the symptoms shortly after injection but without neurological deficits. In conclusion, an epidural HA injection combined with a self-administered exercise program is a promising method and might be a beneficial way to enhance the neurodynamics of nerve roots in LFS and offer an option for steroid treatment. However, this method of epidural HA administration in LFS should be verified in further studies to confirm its efficiency and safety.

Artificial lamina after laminectomy: Progress, applications, and future perspectives

In clinical practice, laminectomy is a commonly used procedure for spinal decompression in patients suffering from spinal disorders such as ossification of ligamentum flavum, lumbar stenosis, severe spinal fracture, and intraspinal tumors. However, the loss of posterior column bony support, the extensive proliferation of fibroblasts and scar formation after laminectomy, and other complications (such as postoperative epidural fibrosis and iatrogenic instability) may cause new symptoms requiring revision surgery. Implantation of an artificial lamina prosthesis is one of the most important methods to avoid post-laminectomy complications. Artificial lamina is a type of synthetic lamina tissue made of various materials and shapes designed to replace the resected autologous lamina. Artificial laminae can provide a barrier between the dural sac and posterior soft tissues to prevent postoperative epidural fibrosis and paravertebral muscle compression and provide mechanical support to maintain spinal alignment. In this paper, we briefly review the complications of laminectomy and the necessity of artificial lamina, then we review various artificial laminae from clinical practice and laboratory research perspectives. Based on a combination of additive manufacturing technology and finite element analysis for spine surgery, we propose a new designing perspective of artificial lamina for potential use in clinical practice.

Hyaluronic Acid: A Review of the Drug Delivery Capabilities of This Naturally Occurring Polysaccharide

The inclusion of physiologically active molecules into a naturally occurring polymer matrix can improve the degradation, absorption, and release profile of the drug, thus boosting the therapeutic impact and potentially even reducing the frequency of administration. The human body produces significant amounts of polysaccharide hyaluronic acid, which boasts exceptional biocompatibility, biodegradability, and one-of-a-kind physicochemical features. In this review, we will examine the clinical trials currently utilizing hyaluronic acid and address the bright future of this versatile polymer, as well as summarize the numerous applications of hyaluronic acid in drug delivery and immunomodulation.

Anti-Adhesion Effect of Composite Film Materials Based on Glycoluril-Modified Sodium Carboxymethyl Cellulose

The aim of the study was to develop composite film materials derived from modified sodium carboxymethyl cellulose and to evaluate their anti-adhesive effects.