On costochondral grafts replacing mandibular condyles in juvenile chronic arthritis. A clinical, histological and experimental study

Abstract: In children with juvenile chronic arthritis (JCA), disturbances of mandibular growth and function may result in involvement of the temporomandibular joints (TMJs). The aim of this thesis was to study the stomatognathic system in JCA children and long-term effects on facial growth of treatment comprising replacement of arthritic mandibular condyles with autogenous costochondral grafts (CCGs) during growth. The aim was also experimentally to study revascularisation and growth of CCGs for mandibular condyle replacement.Subjective symptoms and clinical signs were recorded in 105 JCA children and their TMJs were examined radiographically with orthopantomograms. Clinical findings recorded at surgery and histologic examination of resected arthritic condylar heads and discs were evaluated in 21 TMJs with JCA involvement. Facial growth was studied by cephalometric evaluation until completion of skeletal growth in 12 JCA patients with mandibular hypoplasia or asymmetry treated with replacement of arthritic mandibular condyles with CCGs. Revascularisation and influence of biomechanical stimuli on growth of CCGs used for mandibular condyle replacement were studied in juvenile domestic pigs by microangiographic, direct measurement and fluorochromic labelling techniques.Radiographic mandibular condyle lesions in JCA children were significantly correlated with restricted mouth opening capacity, postnormal occlusion, anterior open bite and mandibular retrognathia. The lower joint compartment of TMJs with radiographic mandibular condyle changes in JCA children with mandibular hypoplasia had considerably more extensive pathological changes than the upper compartments. Severe destructions of the condylar cartilage and condylar bone were found. TMJ pain was a rare finding in these children. Early surgical treatment of mandibular hypoplasia in JCA patients by replacement of arthritic mandibular condyles with CCGs resulted in a considerable growth of the reconstructed mandibles and a good TMJ function. A major drawback was the frequent finding of mandibular overgrowth. Follow-up until after completion of skeletal growth was necessary for an adequate evaluation of facial growth in these patients. The growth plate of CCGs used for mandibular condyle reconstruction was found revascularised from surrounding soft tissues and not from the host mandible. The original growth plate morphology of ribs was changed in CCGs in both TMJ and non-joint-functional environments. The influence of biomechanical stimuli from the TMJ environment was of minor importance for the magnitude of growth of CCGs.Conclusions: Mandibular hypoplasia in JCA children is associated with radiographic mandibular condyle lesions and the lower TMJ compartment seems more involved by pathological changes than the upper one. Replacement of arthritic mandibular condyles with CCGs in order to treat mandibular hypoplasia in JCA children implies a considerable risk for mandibular overgrowth. The magnitude of growth of CCGs is only slightly influenced by the biomechanical stimuli from the TMJ environment, thus indicating an influence of predominantly intrinsic growth factors.Keywords: juvenile chronic arthritis, temporomandibular joints, temporomandibular disorders, costochondral grafts, growth, revascularisation, microangiography, fluorochrome labelling.