New Perspectives of Osteochondral Lesion of the Talus

Osteochondral lesions of the talus(OLT) are the most common articular cartilage defects in the ankle and may cause disability as a result of chronic pain and limited weight-bearing capacity. Numerous treatment strategies for symptomatic OLT have advanced significantly over the past decades. OLT are often managed conservatively for an initial stage before the surgical treatment. However, the conservative management determined solely on symptomatology, and not on the physiological healing. A systematic review for the treatment of OLT demonstrated a 45% success rate of non-operative management. Surgical treatment of OLT is reserved for symptomatic focal lesions that fail to respond to conservative treatments. There are three major operative strategies for OLT, reparative, replacement and regenerative manners. For the reparative modality, arthroscopic bone marrow stimulation(BMS) is widely regarded as the first-line treatment for OLT, as it is a technically undemanding, cost-effective, and minimally invasive procedure with low rates of complication and postoperative pain. Small lesion (<15 mm in diameter or <150mm(2) in size) is the ideal candidate for BMS supported by several literatures. And a study reported the long-term follow-up study to date at 8-20 years after BMS in which 78% of patients had an excellent or good functional outcome score. As a replacement strategy, autologous osteochondral transplantation(AOT) is often indicated for symptomatic large, cystic lesions, including those that have failed previous reparative procedures, such as BMS. Osteochondral autograft transfer carries the inherent advantage over osteochondral allograft of being from the host with fresh viable cartilage, most commonly harvested from the ipsilateral knee. Clinical studies have found favorable results with osteochondral autograft techniques, including a recent systematic review of clinical outcomes at mid-term follow-up demonstrating excellent or good outcomes in 87% of patients. In recent years, Scaffold-based regenerative techniques are getting more attention. Matrix-associated chondrocyte implantation(MACI) is a 2-step procedure in which culture-expanded autologous chondrocytes are seeded on a scaffold, which is then secured in the OLT. More recently, 1-step procedures have been developed in which scaffolds and/or orthobiologics, including bone marrow aspirate concentrate(BMAC) and platelet-rich plasma(PRP), and hyaluronic acid(HA) have been used to augment microfracture with the intention of overcoming the 2-step procedures while concurrently promoting chondrogenic differentiation of endogenous stem cells. Matrix-augmented BMS is one such technique that has been reported with good results in case series. In the future, an advanced strategy for tissue engineering with gene therapy may influence the quality of integration and longevity in treatment of OLT.