In the over 10-year follow-up of 57 cases of primary cranial expansion with distraction by our team, 2 cases have resulted in a bumpy calvarial deformity. These cases are reported in detail.
Case 1 was a 3-year-old patient diagnosed with oxycephaly who underwent calvarial expansion. The post-operative course was uneventful. Since puberty, the cranium began to gradually deform unevenly, requiring contouring surgery 15 years later. CT imaging revealed a wave-shaped outer cortex, and the bone marrow was fatty and yellowish in some areas.
Case 2 was mild trigonocephaly with increased intra-cranial pressure. Frontal advancement was successfully carried out by distraction when the patient was 2 years of age. After six years, a marked bumpy skull deformity in the front of the coronal suture was noted. Wavy cortical bone was also observed by X-ray.
The bumpy deformity on the distracted cranium may have been caused by overreaction during adolescence, mainly in the medulla of the frontal bone, where endochondral ossification occurs at the edge and film ossification occurs at the center. As such, the coronal ring area must be carefully followed-up for a long time after distraction surgery.
