Bone growth occurring during flare-ups may result in the loss of mobility to affected joints, including, if the jaw/mandible is involved, the inability to fully open the mouth, limiting speech and eating. A specific occurrence of a flare-up of this condition in the foot/ankle joints can result in the limited ability to put a foot flat on the ground. Bone growth can also result in the immobilization of the hip or knee, affecting the individual's ability to walk. Extra bone formation around the rib cage restricts the expansion of lungs and diaphragm causing respiratory complications.