Differential growth on sutures of tendon cells derived from torn human rotator cuff

A Hybrid Electrospun-Extruded Polydioxanone Suture for Tendon Tissue Regeneration

Many surgical tendon repairs fail despite advances in surgical materials and techniques. Tendon repair failure can be partially attributed to the tendon's poor intrinsic healing capacity and the repurposing of sutures from other clinical applications. Electrospun materials show promise as a biological scaffold to support endogenous tendon repair, but their relatively low tensile strength has limited their clinical translation. It is hypothesized that combining electrospun fibers with a material with increased tensile strength may improve the suture's mechanical properties while retaining biophysical cues necessary to encourage cell-mediated repair. This article describes the production of a hybrid electrospun-extruded suture with a sheath of submicron electrospun fibers and a core of melt-extruded fibers. The porosity and tensile strength of this hybrid suture is compared with an electrospun-only braided suture and clinically used sutures Vicryl and polydioxanone (PDS). Bioactivity is assessed by measuring the adsorbed serum proteins on electrospun and melt-extruded filaments using mass spectrometry. Human hamstring tendon fibroblast attachment and proliferation were quantified and compared between the hybrid and control sutures. Combining an electrospun sheath with melt-extruded cores created a hybrid braid with increased tensile strength (70.1 ± 0.3N) compared with an electrospun only suture (12.9 ± 1 N, p < 0.0001). The hybrid suture had a similar force at break to clinical sutures, but lower stiffness and stress. The Young's modulus was 772.6 ± 32 MPa for the hybrid suture, 1693.0 ± 69 MPa for PDS, and 3838.0 ± 132 MPa for Vicryl, p < 0.0001. Hybrid sutures had lower overall porosity than electrospun-only sutures (40 ± 4% and 60 ± 7%, respectively, p = 0.0018) but had a significantly larger overall porosity and average pore diameter compared with surgical sutures. There were similar clusters of adsorbed proteins on electrospun and melt-extruded filaments, which were distinct from PDS. Tendon fibroblast attachment and cell proliferation on hybrid and electrospun sutures were significantly higher than on clinical sutures. This study demonstrated that a bioactive suture with increased tensile strength and lower stiffness could be produced by adding a core of 10 μm melt-extruded fibers to a sheath of electrospun fibers. In contrast to currently used sutures, the hybrid sutures promoted a bioactive response: serum proteins adsorbed, and fibroblasts attached, survived, grew along the sutures, and adopted appropriate morphologies.

The Chinese knotting technique assist anatomical anterior cruciate ligament reconstruction for aggressive rehabilitation

Aggressive rehabilitation after anterior cruciate ligament (ACL) reconstruction may result in better clinical outcomes and fewer complications such as knee stiffness and weakness. We explored the effect of the Chinese knotting technique (CKT) for aggressive rehabilitation after ACL reconstruction. Ninety-one anatomical ACL reconstruction cases from 2016 to 2020 were retrospectively reviewed. All patients were operated by the same senior physician and his team. According to the reconstruction with or without CKT, the patients were divided into 2 groups. Both groups received aggressive rehabilitation. The follow-up time of 91 patients was more than 2 years. In total, 43 out of the 91 patients were in the CKT group, and 48 were in the routine group. The knee joint kinematics recorded by Opti_Knee revealed no significant difference among the CKT group, the routine group, and healthy adults at 3, 6, 12, and 24 months after the operation, respectively. The internal and external rotation angle and the anteroposterior displacement at 3 and 6 months after the operation in the CKT group were smaller than in the routine group and were similar to that of the healthy adults. There was no significant difference in flexion and extension angle, varus or valgus angle, proximal-distal displacement, or the internal or external displacement between the 2 groups. In addition, there was no significant difference in 6 degrees of freedom of the knee between the 2 groups at 12 and 24 months after the operation, respectively, which was similar to healthy adults. Compared to the routine group, the International Knee Documentation Committee scores were significantly higher in the CKT group at the 3, 6, and 12 months, respectively, but no difference was observed at 24 months (P = .749). The Lysholm score was significantly higher in the CKT group at the 3 and 6 months postoperatively, while there was no difference at 12 and 24 months, respectively. In short-term observation, the ACL reconstruction with CKT, which can sustain aggressive rehabilitation and prevent the loosening of ACL graft, can lead to better clinical outcomes and kinematics recovery of the knee compared to routine technique.

Augmenting endogenous repair of soft tissues with nanofibre scaffolds

As our ability to engineer nanoscale materials has developed we can now influence endogenous cellular processes with increasing precision. Consequently, the use of biomaterials to induce and guide the repair and regeneration of tissues is a rapidly developing area. This review focuses on soft tissue engineering, it will discuss the types of biomaterial scaffolds available before exploring physical, chemical and biological modifications to synthetic scaffolds. We will consider how these properties, in combination, can provide a precise design process, with the potential to meet the requirements of the injured and diseased soft tissue niche. Finally, we frame our discussions within clinical trial design and the regulatory framework, the consideration of which is fundamental to the successful translation of new biomaterials.

Local tissue reaction to implantation of biodegradable suture materials

Morphological changes in tissues adjacent to the implant were studied 1, 2, 6, and 12 months after implantation of biodegradable suture materials (catgut thread, DemeTECH polyfilament thread, and Surgilactin monofilament thread) into subcutaneous fat of rats. Tissue reaction to implantation of different suture materials developed as usual in response to a wound process and to a foreign body. By the end of month 1. the stage of traumatic perifocal inflammation was replaced in all groups by the proliferative phase with formation of new vessels and connective tissue. A trend to reduction of the productive inflammation activity from month 1 to month 12 was noted. Complete degeneration of the material after 12 months with complete recovery of the histoarchitecture of the adjacent tissues (restitution) was detected only after implantation of DemeTECH polyfilament thread.

In vitro and in vivo cytocompatibility of electrospun nanofiber scaffolds for tissue engineering applications

An electrospun polymeric-based nanofibrous scaffold mimicking the extracellular matrix and serving as a temporary support for cell growth, adhesion, migration and proliferation.

Autologous tenocyte injection for the treatment of severe, chronic resistant lateral epicondylitis: a pilot study

BACKGROUND

Severe chronic lateral epicondylitis (LE) is associated with degenerative tendon changes, extracellular matrix breakdown, and tendon cell loss. On the basis of positive outcomes from preclinical studies, this study is the first clinical trial of autologous tenocyte injection (ATI) on severe tendinopathy associated with chronic LE.

HYPOTHESIS

Autologous tenocyte injection is a safe and effective procedure that enables a reduction in pain and improvement in function in resistant LE.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients with severe refractory LE underwent clinical evaluation and magnetic resonance imaging (MRI) before intervention. A patellar tendon needle biopsy was performed under local anesthetic, and tendon cells were expanded by in vitro culture. Tenocytes used for the injection were characterized by flow cytometry and real-time polymerase chain reaction. Autologous tenocytes were injected into the site of tendinopathy identified at the origin of the extensor carpi radialis brevis tendon under ultrasound guidance on a single occasion. Patients underwent serial clinical evaluations and repeat MRI at 12 months after intervention.

RESULTS

A total of 20 consecutive patients were included in the study. Three patients withdrew consent after enrollment and before ATI. No adverse event was reported at either biopsy or injection sites. Furthermore, no infection or excessive fibroblastic reaction was found in any patient at the injection site. Clinical evaluation revealed an improvement in mean visual analog scale scores, for a maximum pain score from 5.94 at the initial assessment to 0.76 at 12 months (P < .001). Mean quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) and grip strength scores also significantly improved over the 12-month follow-up (QuickDASH score, 45.88 [baseline] to 3.84; grip strength, 20.17 kg [baseline] to 37.38 kg; P < .001). With use of a validated MRI scoring system, the grade of tendinopathy at the common extensor origin improved significantly by 12 months (P < .001). One patient elected to proceed to surgery 3 months after ATI following a reinjury at work.

CONCLUSION

In this study, patients with chronic LE who had previously undergone an unsuccessful full course of nonoperative treatment showed significantly improved clinical function and structural repair at the origin of the common extensor tendon after ATI. This novel treatment is encouraging for the treatment of tendinopathy and warrants further evaluation.

Synthetic and degradable patches: an emerging solution for rotator cuff repair

The use of rotator cuff augmentation has increased dramatically over the last 10 years in response to the high rate of failure observed after non-augmented surgery. However, although augmentations have been shown to reduce shoulder pain, there is no consensus or clear guideline as to what is the safest or most efficacious material. Current augmentations, either available commercially or in development, can be classified into three categories: non-degradable structures, extra cellular matrix (ECM)-based patches and degradable synthetic scaffolds. Non-degradable structures have excellent mechanical properties, but can cause problems of infection and loss of integrity in the long-term. ECM-based patches usually demonstrate excellent biological properties in vitro, but studies have highlighted complications in vivo due to poor mechanical support and to infection or inflammation. Degradable synthetic scaffolds represent the new generation of implants. It is proposed that a combination of good mechanical properties, active promotion of biological healing, low infection risk and bio-absorption are the ideal characteristics of an augmentation material. Among the materials with these features, those processed by electrospinning have shown great promis. However, their clinical effectiveness has yet to be proven and well conducted clinical trials are urgently required.