Injectable scaffold augmentation is a promising modality for single-stage cartilage repair. According to published studies, cartilage repair with scaffold augmentation has improved clinical outcomes, radiological fill, and histological repair compared with microfracture alone. Injectable scaffolds have the versatility to be used in large and irregularly shaped lesions. With correct preparation, they can be applied to lesions on the femoral condyle that may be vertical, or even inverted lesions such as those in the patella. They can be combined with bone marrow aspirate concentrate (BMAC) to provide mesenchymal stem cells (MSCs), thereby avoiding the need for microfracture. This protects the subchondral plate, preventing biomechanical alteration and potentially resulting in improved long-term outcomes. In this article, we demonstrate the utility of injectable scaffolds and their combination with BMAC.

Figure 5. (A) Anteroposterior and (B) lateral radiographs of the left femur at 2-year follow-up, showing evidence of full bony union of the fracture.

Background: Injectable scaffold augmentation has been gaining traction as a promising modality for single-stage cartilage repair. It involves the use of a biological scaffold that augments microfracture techniques by aiding in clot stabilization and maturation. The scaffold provides a matrix that helps with mesenchymal stem cell (MSC) retention and encourages differentiation along a chondrogenic lineage. Bone marrow aspirate concentrate (BMAC) has also been proposed as an alternative source of MSCs to microfracture, and it can potentially avoid the pitfalls of microfracture techniques. Indications: Injectable scaffold augmentation to microfracture techniques are recommended in lesions >4 cm, as long-term follow-up has shown increasing failure over time with microfracture alone. Technique Description: We describe a technique of autologous matrix-induced chondrogenesis using CartiFill, a porcine-derived type 1 collagen scaffold, combined with BMAC as a source of MSCs (avoiding the use of microfracture). Results: Injectable scaffold augmentation has been shown in recent studies to lead to better radiological fill, higher quality of histological repair, and better clinical outcomes as compared with microfracture alone. These injectable scaffolds have the versatility to be used on lesions which have traditionally been considered difficult to address, such as vertical or inverted lesions. Moreover, the use of scaffolds allows the repair to be further augmented with BMAC which provides a source of MSCs without the need to perform microfracture and perforate the subchondral bone. Discussion/Conclusion: Scaffold augmentation is a promising technique that improves upon the results of conventional microfracture repair by allowing augmentation with BMAC, as well as giving surgeons the versatility to apply the scaffold on vertical/inverted lesions. BMAC is also a viable alternative source of MSCs for cartilage repair.

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