Congenital lumbar spinal stenosis with ossification of the ligamentum flavum in achondroplasia: a case report

INTRODUCTION Achondroplasia is a genetic disorder of bone growth. Congenital spinal stenosis is a well-known complication of this disease, but, to the best of our knowledge, no cases involving combined stenosis with congenital lumbar spinal stenosis and ossification of the ligamentum flavum in achondroplasia have been reported previously. In this report, we describe a case of a patient with congenital spinal stenosis with achondroplasia combined with ossification of the ligamentum flavum at the lumbar spine, which we treated with decompressive surgery. CASE PRESENTATION A 75-year-old Japanese woman with achondroplasia was unable to walk due to a neurological deficit of the lower extremities caused by congenital spinal stenosis that resulted from achondroplasia and ossification of the ligamentum flavum at the lumbar spine. Congenital spinal stenosis was observed from L1 to L5, and ossification of the ligamentum flavum was identified from L1/2 to L3/4. A decompressive laminectomy from L1 to L5 and removal of the ossification of the ligamentum flavum were performed. The patient's neurological symptoms improved after surgery. She could walk with T-cane at the time of her four-year follow-up examination. CONCLUSION In this report, we describe what is, to the best of our knowledge, the first known published case of ossification of the ligamentum flavum in congenital spinal stenosis associated with achondroplasia at the lumbar spine. Although resection of the ossification of the ligamentum flavum at the congenital spinal stenosis at the lumbar spine was technically difficult because of congenital narrowing of the spinal canal, thickening of the lamina and adhesion of the ossified ligamentum flavum, a wide laminectomy and resection of the ossification of the ligamentum flavum resulted in acceptable improvement of the patient's neurological symptoms.