A Rare Case of Ossification of Ligamentum Flavum presenting as Dorsal Myelopathy in Achondroplasia

Ossification of the ligamentum flavum (OLF) was discovered by Polgar and further described by Yamaguchi and Isuruni [1]. Among the thoracic myelopathies, its incidence is less than that of ossification of the posterior longitudinal ligament (OPLL) and higher than that of herniated nucleus pulposus (HNP) [1]. It is mostly prevalent in Japan and other East Asian countries such as Korea and China [2]. Achondroplasia is a genetic disorder of bone growth with congenital spinal stenosis being a well known complication [3]. Degenerative changes of the spine, such as disc herniation, degenerative spondylosis and arthrosis result in worsening of stenosis [4]. However, symptomatic spinal stenosis due by ossification of the ligamentum flavum (OLF) in achondroplasia is extremely rare [5,6]. We present a rare case of spinal stenosis due to ossified ligamentum flavum in a 30 year old Indian female of achondroplasia presenting as dorsal myelopathy.