Osteochondral Tissue Engineering: Translational Research and Turning Research into Products

Talar OsteoPeriostic Grafting from the Iliac Crest (TOPIC): Two-Year Prospective Results of a Novel Press-Fit Surgical Technique for Large, Complex Osteochondral Lesions of the Medial Talus

BACKGROUND

Press-fit Talar OsteoPeriostic grafting from the Iliac Crest (TOPIC) is a novel technique for the treatment of large osteochondral lesions of the talus. The purpose of the present study was to prospectively evaluate the 2-year clinical outcomes for patients with medial osteochondral lesions of the talus that were treated with the TOPIC procedure.

METHODS

Forty-three patients were prospectively assessed before and 24 months after the TOPIC procedure. All procedures were performed through a medial distal tibial osteotomy. Clinical assessment preoperatively and at 24 months of follow-up included determination of the Numeric Rating Scale (NRS) scores for pain during walking (primary outcome), at rest, during running, and during stair-climbing. The Foot and Ankle Outcome Score (FAOS) and the Mental Component Summary (MCS) score and Physical Component Summary (PCS) score of the Short Form-36 (SF-36) were also assessed. A computed tomography (CT) scan was performed 12 weeks postoperatively to assess union of the distal tibial osteotomy site and at 1 and 2 years postoperatively to assess consolidation of the graft as well as cyst development in the graft.

RESULTS

All enrolled patients were available for follow-up. The median NRS score for pain during walking improved from 7 points preoperatively to 2 points at 2 years postoperatively (p < 0.001). All other NRS scores for pain improved significantly. All FAOS subscale scores improved significantly, including those for pain (from 53 to 75), symptoms (from 50 to 61), activities of daily living (from 68 to 88), sports (from 30 to 55), and quality of life (from 19 to 38). The SF-36 PCS score improved from 43 to 48 (p < 0.001), and the MCS score changed from 28 to 26 (p > 0.05). There was a 100% rate of union of the osteotomy site at the distal tibia and 100% of the grafts showed consolidation at 1 and 2 years postoperatively.

CONCLUSIONS

The TOPIC procedure for large osteochondral lesions of the medial talar dome is an effective technique that resulted in significant improvement exceeding the minimal clinically important difference in pain scores (primary outcome) as well as in other outcomes, with 100% consolidation of the grafts.

LEVEL OF EVIDENCE

Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.

Dual-Nozzle 3D Printed Nano-Hydroxyapatite Scaffold Loaded with Vancomycin Sustained-Release Microspheres for Enhancing Bone Regeneration

Background

Successful treatment of infectious bone defect remains a major challenge in the orthopaedic field. At present, the conventional treatment for infectious bone defects is surgical debridement and long-term systemic antibiotic use. It is necessary to develop a new strategy to achieve effective bone regeneration and local anti-infection for infectious bone defects.

Methods

Firstly, vancomycin / poly (lactic acid-glycolic acid) sustained release microspheres (VAN/PLGA-MS) were prepared. Then, through the dual-nozzle 3D printing technology, VAN/PLGA-MS was uniformly loaded into the pores of nano-hydroxyapatite (n-HA) and polylactic acid (PLA) scaffolds printed in a certain proportion, and a composite scaffold (VAN/MS-PLA/n-HA) was designed, which can not only promote bone repair but also resist local infection. Finally, the performance of the composite scaffold was evaluated by in vivo and in vitro biological evaluation.

Results

The in vitro release test of microspheres showed that the release of VAN/PLGA-MS was relatively stable from the second day, and the average daily release concentration was about 15.75 μg/mL, which was higher than the minimum concentration specified in the guidelines. The bacteriostatic test in vitro showed that VAN/PLGA-MS had obvious inhibitory effect on Staphylococcus aureus ATCC-29213. Biological evaluation of VAN/MS-PLA/n-HA scaffolds in vitro showed that it can promote the proliferation of adipose stem cells. In vivo biological evaluation showed that VAN/MS-PLA/n-HA scaffold could significantly promote bone regeneration.

Conclusion

Our research shows that VAN/MS-PLA/n-HA scaffolds have satisfying biomechanical properties, effectively inhibit the growth of Staphylococcus aureus, with good biocompatibility, and effectiveness on repairing bone defects. The VAN/MS-PLA/n-HA scaffold provide the clinic with an application prospect in bone tissue engineering.

Talar OsteoPeriostic grafting from the Iliac Crest (TOPIC) for lateral osteochondral lesions of the talus: operative technique

OBJECTIVE

To provide a natural scaffold, good quality cells, and growth factors to facilitate replacement of the complete osteochondral unit with matching talar curvature for large osteochondral lesions of the lateral talar dome.

INDICATIONS

Symptomatic primary and non-primary lateral osteochondral lesions of the talus not responding to conservative treatment. The anterior-posterior or medial-lateral diameter should exceed 10 mm on computed tomography (CT) for primary lesions; for secondary lesions, there are no size limitations.

CONTRAINDICATIONS

Tibiotalar osteoarthritis grade III, malignancy, active infectious ankle joint pathology, and hemophilic or other diffuse arthropathy.

SURGICAL TECHNIQUE

Anterolateral arthrotomy is performed after which the Anterior TaloFibular Ligament (ATFL) is disinserted from the fibula. Additional exposure is achieved by placing a Hintermann distractor subluxating the talus ventrally. Thereafter, the osteochondral lesion is excised in toto from the talar dome. The recipient site is micro-drilled in order to disrupt subchondral bone vessels. Thereafter, the autograft is harvested from the ipsilateral iliac crest with an oscillating saw, after which the graft is adjusted to an exactly fitting shape to match the extracted lateral osteochondral defect and the talar morphology as well as curvature. The graft is implanted with a press-fit technique after which the ATFL is re-inserted followed by potential augmentation with an InternalBrace™ (Arthrex, Naples, FL, USA).

POSTOPERATIVE MANAGEMENT

Non-weightbearing cast for 6 weeks, followed by another 6 weeks with a walking boot. After 12 weeks, a computed tomography (CT) scan is performed to assess consolidation of the inserted autograft. The patient is referred to a physiotherapist.

Novel advances in strategies and applications of artificial articular cartilage

Artificial articular cartilage (AC) is extensively applied in the repair and regeneration of cartilage which lacks self-regeneration capacity because of its avascular and low-cellularity nature. With advances in tissue engineering, bioengineering techniques for artificial AC construction have been increasing and maturing gradually. In this review, we elaborated on the advances of biological scaffold technologies in artificial AC including freeze-drying, electrospinning, 3D bioprinting and decellularized, and scaffold-free methods such as self-assembly and cell sheet. In the following, several successful applications of artificial AC built by scaffold and scaffold-free techniques are introduced to demonstrate the clinical application value of artificial AC.

Bio-inspired zonal-structured matrices for bone-cartilage interface engineering

Design and development of scaffold structures for osteochondral (OC) interface regeneration is a significant engineering challenge. Recent efforts are aimed at recapitulating the unique compositional and hierarchical structure of an OC interface. Conventional scaffold fabrication techniques often have limited design control and reproducibility, and the development of OC scaffolds with zonal hierarchy and structural integrity between zones is especially challenging. In this study, a series of multi-zonal and gradient structures were designed and fabricated using three-dimensional bioprinting. We developed OC scaffolds with bi-phasic and tri-phasic configurations to support the zonal structure of OC tissue, and gradient scaffold configurations to enable smooth transitions between the zones to more closely mimic a bone-cartilage interface. A biodegradable polymer, polylactic acid, was used for the fabrication of zonal/gradient scaffolds to provide mechanical strength and support OC function. The formation of the multi-zonal and gradient scaffolds was confirmed through scanning electron microscopy imaging and micro-computed tomography scanning. Precisely controlled hierarchy with tunable porosity along the scaffold length established the formation of the bio-inspired scaffolds with different zones/gradient structure. In addition, we also developed a novel bioprinting method to selectively introduce cells into desired scaffold zones of the zonal/gradient scaffolds via concurrent printing of a cell-laden hydrogel within the porous template. Live/dead staining of the cell-laden hydrogel introduced in the cartilage zone showed uniform cell distribution with high cell viability. Overall, our study developed bio-inspired scaffold structures with structural hierarchy and mechanical integrity for bone-cartilage interface engineering.

Gradient scaffold with spatial growth factor profile for osteochondral interface engineering

Osteochondral (OC) matrix design poses a significant engineering challenge due to the complexity involved with bone-cartilage interfaces. To better facilitate the regeneration of OC tissue, we developed and evaluated a biodegradable matrix with uniquely arranged bone and cartilage supporting phases: a poly(lactic-co-glycolic) acid (PLGA) template structure with a porosity gradient along its longitudinal axis uniquely integrated with hyaluronic acid hydrogel. Micro-CT scanning and imaging confirmed the formation of an inverse gradient matrix. Hydroxyapatite was added to the PLGA template which was then plasma-treated to increase hydrophilicity and growth factor affinity. An osteogenic growth factor (bone morphogenetic protein 2; BMP-2) was loaded onto the template scaffold via adsorption, while a chondrogenic growth factor (transforming growth factor beta 1; TGF-β1) was incorporated into the hydrogel phase. Confocal microscopy of the growth factor loaded matrix confirmed the spatial distribution of the two growth factors, with chondrogenic factor confined to the cartilaginous portion and osteogenic factor present throughout the scaffold. We observed spatial differentiation of human mesenchymal stem cells (hMSCs) into cartilage and bone cells in the scaffolds in vitro: cartilaginous regions were marked by increased glycosaminoglycan production, and osteogenesis was seen throughout the graft by alizarin red staining. In a dose-dependent study of BMP-2, hMSC pellet cultures with TGF-β1 and BMP-2 showed synergistic effects on chondrogenesis. These results indicate that development of an inverse gradient matrix can spatially distribute two different growth factors to facilitate chondrogenesis and osteogenesis along different portions of a scaffold, which are key steps needed for formation of an osteochondral interface.

Growing a backbone - functional biomaterials and structures for intervertebral disc (IVD) repair and regeneration: challenges, innovations, and future directions

Back pain and associated maladies can account for an immense amount of healthcare cost and loss of productivity in the workplace. In particular, spine related injuries in the US affect upwards of 5.7 million people each year. The degenerative disc disease treatment almost always arises due to a clinical presentation of pain and/or discomfort. Preferred conservative treatment modalities include the use of non-steroidal anti-inflammatory medications, physical therapy, massage, acupuncture, chiropractic work, and dietary supplements like glucosamine and chondroitin. Artificial disc replacement, also known as total disc replacement, is a treatment alternative to spinal fusion. The goal of artificial disc prostheses is to replicate the normal biomechanics of the spine segment, thereby preventing further damage to neighboring sections. Artificial functional disc replacement through permanent metal and polymer-based components continues to evolve, but is far from recapitulating native disc structure and function, and suffers from the risk of unsuccessful tissue integration and device failure. Tissue engineering and regenerative medicine strategies combine novel material structures, bioactive factors and stem cells alone or in combination to repair and regenerate the IVD. These efforts are at very early stages and a more in-depth understanding of IVD metabolism and cellular environment will also lead to a clearer understanding of the native environment which the tissue engineering scaffold should mimic. The current review focusses on the strategies for a successful regenerative scaffold for IVD regeneration and the need for defining new materials, environments, and factors that are so finely tuned in the healthy human intervertebral disc in hopes of treating such a prevalent degenerative process.

Talar OsteoPeriostic grafting from the Iliac Crest (TOPIC) for large medial talar osteochondral defects : Operative technique

Objective

Provision of a natural scaffold, good quality cells, and growth factors in order to facilitate the replacement of the complete osteochondral unit with matching talar curvature for large medial primary and secondary osteochondral defects of the talus.

Indications

Symptomatic primary and secondary medial osteochondral defects of the talus not responding to conservative treatment; anterior–posterior or medial–lateral diameter >10 mm on computed tomography (CT); closed distal tibial physis in young patients.

Contraindications

Tibiotalar osteoarthritis grade III; multiple osteochondral defects on the medial, central, and lateral talar dome; malignancy; active infectious ankle joint pathology.

Surgical technique

A medial distal tibial osteotomy is performed, after which the osteochondral defect is excised in toto from the talar dome. The recipient site is microdrilled in order to disrupt subchondral bone vessels. Then, the autograft is harvested from the ipsilateral iliac crest with an oscillating saw, after which the graft is adjusted to an exact fitting shape to match the extracted osteochondral defect and the talar morphology as well as curvature. The graft is implanted with a press-fit technique after which the osteotomy is reduced with two 3.5 mm lag screws and the incision layers are closed. In cases of a large osteotomy, an additional third tubular buttress plate is added, or a third screw at the apex of the osteotomy.

Postoperative management

Non-weight bearing cast for 6 weeks, followed by another 6 weeks with a walking boot. After 12 weeks, a CT scan is performed to assess consolidation of the osteotomy and the inserted autograft. The patient is referred to a physiotherapist.

Results

Ten cases underwent the TOPIC procedure, and at 1 year follow-up all clinical scores improved. Radiological outcomes showed consolidation of all osteotomies and all inserted grafts showed consolidation. Complications included one spina iliaca anterior avulsion and one hypaesthesia of the saphenous nerve; in two patients the fixation screws of the medial malleolar osteotomy were removed.

The Use of Particulated Juvenile Allograft Cartilage for the Repair of Porcine Articular Cartilage Defects

BACKGROUND

The repair of porcine articular cartilage defects by using particulated juvenile allograft cartilage (PJAC) has demonstrated good short-term clinical efficacy, but the repair process and mechanism have not been fully elucidated.

PURPOSE

To study the efficacy of PJAC in repairing full-thickness cartilage defects and to provide an experimental basis for its clinical application.

STUDY DESIGN

Controlled laboratory study.

METHODS

Thirty Guizhou minipigs were randomly divided into an experimental group and control group. An 8-mm cylindrical full-thickness cartilage defect was created in the femoral trochlea of either knee in all minipigs. The experimental group received the PJAC transplantation (PJAC group; n = 15) and the control group received autologous cartilage chips (ACC group; n = 15). Five minipigs were euthanized at 1, 3, and 6 months in each group to obtain samples, which were evaluated by general view of the knee joint and histomorphometry of the chondral defect area (hematoxylin and eosin, safranin O). International Cartilage Repair Society (ICRS) II semiquantitative evaluation and collagen type II staining immunohistochemistry were also performed.

RESULTS

All 30 Guizhou minipigs were followed; there was no infection or incision healing disorder after the operation. At 1 month postoperatively, more hyaline cartilage was found in the ACC group (29.4%) compared with the PJAC group (20.1%) (P < .05); there was no statistical difference between the 2 groups at 3 and 6 months after operation. The fibrocartilage content in the ACC group was significantly more than that in the PJAC group at 1 and 3 months postoperatively (27.4% vs 18.2% and 49.9% vs 41.1%, respectively; P < .05); significant differences disappeared at 6 months postoperatively. The PJAC group produced more fibrous tissue than the ACC group at 1 and 3 months postoperatively (60.1% vs 40.6% and 38.8% vs 24.4%, respectively; P < .05) but showed no statistical difference at 6 months postoperatively. Regarding the ICRS II scores, those of the ACC group were significantly better than the scores of the PJAC group in some subclasses at 3 and 6 months postoperatively. The positive rates of immunohistochemical staining in the ACC group were higher at 1 and 3 months postoperatively than those in the PJAC group (54.2% vs 37.8% and 46.4% vs 34.4%, respectively; P < .05). The difference was not statistically significant between the 2 groups at 6 months postoperatively.

CONCLUSION

Both PJAC and ACC can produce a good repair effect on cartilage defects. At 1 and 3 months postoperatively, ACC resulted in better outcomes than PJAC, but there was no statistical difference in the repair effect between the 2 techniques at 6 months postoperatively.

CLINICAL RELEVANCE

Based on this animal experiment, further clinical studies are needed to investigate PJAC as a possible alternative first-line treatment for cartilage defects.