The surgical management of refractory talar osteochondral lesions of the talus (OLTs) has generally produced good results. Initial management of these lesions most often involves arthroscopy and microfracture/curettage.^{1, 2} The resulting regenerative tissue is fibrocartilage (Fig. 17-1). Symptomatic improvement is experienced in approximately 85% of cases in studies with long-term follow-up.^{1, 2, 3} Larger lesions (>1 cm²) and lesions with cystic change often require secondary procedures such as osteochondral allograft/autograft transfer system (OATS) or autologous chondrocyte implantation (ACI).^{4, 5, 6, 7} Traditionally, these procedures require the use of an open technique, often with the added morbidity associated with osteotomies for adequate exposure.

The recent introduction of fresh juvenile allograft chondrocytes for the treatment of osteochondral lesions has created a potential tool for the treatment of OLTs refractory to microfracture. This method, which also obviates the need for tibial or fibular osteotomies, reproduces hyaline cartilage architecture (see Fig. 17-1) without the morbidity and technical difficulties attendant to other currently available restorative techniques. Juvenile articular allograft currently is available as a pre-packaged, off-the-shelf finely diced preparation from donors aged less than 13 years with a high chondrocyte viability (Fig. 17-2). Current recommendations suggest the use of one package for coverage of up to a 2.5-cm² defect.

DeNovo NT offers an efficient, one-step allogeneic alternative to ACI for treatment of osteochondral lesions of the talus. Benefits include readily available young and healthy chondrocytes, no donor-site morbidity, and lack of time delay for chondrocyte culturing as is necessary for ACI or matrix-induced autologous chondrocyte implantation (MACI).⁸ In addition, the use of DeNovo NT does not exclude the possibility of using other cartilage restoration techniques if needed in the future. A disadvantage of this technology is that harvested cartilage must be used within 2 weeks. As a result, it is imperative to plan to have the appropriate amount of graft available for the size of the lesion so that there is no shortage or excess.

The ideal patient for the use of DeNovo NT is a young patient (<50 years) with a symptomatic isolated talar osteochondral lesion that has failed conservative treatment and previous microfracture. Large lesions (>1 cm²) are less likely to respond to microfracture and are a relative indication. Large cystic bone defects are still an indication for OATS. Kissing lesions, global osteoarthritis, or active infection are contraindications.⁹ Standing weight-bearing ankle radiographs, as well as magnetic resonance and computed tomography scans, are valuable in localizing the lesion and assessing depth of bone involvement. Instability or malalignment of the ankle must be corrected at the time of surgery.