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Development of a patient-specific TMJ prosthesis2599Heterotopic OssificationA last point of discussion that has to be touched upon in light of reattachment of the LPM’s enthesis, is the occurrence of heterotopic ossification (HE).(62) HE is defined as ‘a heterogeneous disorder characterized by pathologic endochondral ossification with hematopoietic bone marrow in soft tissues, such as subcutaneous tissue, skeletal muscle, or fibrous tissue adjacent to joints’.(63) About 10% of HE cases result in limitations in range of motion. Once it develops, surgical removal is the only effective treatment, followed by local irradiation, which in turn may induce malignancy, and/or nonsteroidal anti-inflammatory agents to prevent recurrence.(64) A strong relationship between trauma (e.g., arthroplasty) and the involvement of multiple organ systems seems to exclude the influence of the type of material or its surface characteristics.(63) An important question is whether the pores of the titanium scaffold must be filled with particulate bone, calcium phosphate, stem cells, or growth factors to enhance bone formation and guarantee bony union with the reattached enthesis. In a sheep model of TMJ replacement, postoperative function suggested that filling the scaffold with autologous bone chips was sufficient.(19) The addition of calcium phosphate may hinder reattachment, even if more bone will be formed within the pores, and the addition of bone marrow-derived mesenchymal stem cells has not been clinically proven to enhance bony fusion.(65–67)Even though an increase in movement capabilities can be seen by using this method, longstanding limitations of lateral movements cannot be undone by lateral pterygoid reattachment. Disuse atrophy of the lateral pterygoid muscle does not appear to be reversed by exercise. Supplementation with branched-chain amino acids and anabolic steroids was not investigated in that respect.ConclusionA careful analysis of the requirements for a successful TMJ replacement has led to the development of a new type of individualized, artificial joint that mimics both normal joint anatomy and function. Even though various Nikolas de Meurechy NW.indd 259 05-06-2024 10:14