The treatment of temporomandibular joint (TMJ) ankylosis is a challenging problem. An excellent review paper that highlights recent developments, with a specific focus on graft materials for condylar reconstruction, has been published by Khadka and Hu. To date, no single method has produced uniformly successful results. Reconstruction with autologous bone grafts, to allow adaptive growth and remodelling, represents the standard treatment in juveniles, while total alloplastic replacement is commonly used in adults, with neither being ideal and both sometimes leading to unwanted adverse effects.
Over the last 25 years, multiple studies have investigated TMJ characteristics, and while this characterization is not complete, these data have created a solid foundation for tissue-engineering research. Recent advances may provide a credible surgical alternative to traditional strategies, with the prospect of using suitably engineered resorbable scaffolds, appropriate biochemical signals, and cell transplantation under investigation worldwide. The latest composite materials offer the opportunity to combine biodegradable matrices and osteogenic inorganic phases, such as hydroxyapatite, thus creating nanostructured scaffolds with tailored bioactivity and improved physical and mechanical properties ( Fig. 1 ).
This trend is explained by the fact that an off-the-shelf product, thus immediately available, would be an ideal graft both from a surgical and commercial standpoint. The application of a cell-free implant that can be reshaped intraoperatively, with the advantages of a one-step simplified procedure plus reduced costs, as well as being ‘smart’ enough to provide the joint with the appropriate stimuli to induce orderly and durable tissue regeneration, has attracted great attention in the orthopaedic community.
Kon et al. highlighted the safety and potential of this approach using a knee joint model: patients were evaluated repeatedly through magnetic resonance imaging (MRI) analysis over 5 years of follow-up and showed stable clinical outcomes for both tibiofemoral and patellofemoral lesions, regardless of age, lesion size, and previous/combined surgery. The cell-mediated remodelling induced by the scaffold properties, along with its progressive reabsorption, favoured complete repair of the osteochondral unit.
Mehrotra et al. furthered this rationale using a hydroxyapatite/collagen scaffold (60:40 ratio) that was carved to the shape of the condyle after gap arthroplasty in young patients (age 4–16 years) with TMJ ankylosis ( Fig. 2 ).