Multifactorial Pathological Hip Subluxation in Neurofibromatosis Type-1 (NF1) Due to Intra-Articular Plexiform Neurofibroma, Lumbar Radiculopathy and Neurofibromatous Polyneuropathy

Neurofibromatosis type-1 (NF1) is a multisystem disorder with very rare descriptions of hip instability. We report a case of a 37-year-old man with known NF1 and childhood-onset of left foot drop, who developed persistent left hip pain following a minor trauma. Physical examination revealed left-sided mild foot drop, hip abductor weakness, bilateral sensory loss in feet and an antalgic gait. Work-up revealed anterolateral subluxation of the left femoral head along with left hip plexiform neurofibroma (PN), dysplastic and degenerative changes, neurofibromatous neuropathy and chronic left L5 radiculopathy. Initial improvement after surgical resection of the PN was unsustained and followed by increasing pain and recurrent hip subluxation, prompting a total hip arthroplasty which resulted in marked improvement of symptoms. Our patient, unlike those in other reports, illustrates multiple aetiologies of hip dislocation in NF1 including local factors, lumbar radiculopathy and polyneuropathy, reinforcing the importance of a multidisciplinary approach in the management of such cases.