Dorsal midline hemivertebra at the lumbosacral junction: report of 2 cases.

Congenital scoliosis from laterally located hemivertebrae at the lumbosacral junction has been described previously. However, dorsally located midline hemivertebrae at this location have not been reported. The authors describe the presentation, treatment, and outcomes of 2 patients (1 male and 1 female) with this rare malformation. All clinical and radiographic records were reviewed. Outcomes were recorded using survey instruments (Oswestry Disability Index and the 36-Item Short Form Health Survey). Radiographic assessment of bony fusion was performed using CT scanning 1 year after surgery. Both patients presented with back and leg pain, urinary hesitancy/incontinence, difficulty sitting and lying down, waddling gait, and restriction of movement. Imaging showed a wedge-shaped dorsal deformity that stretched the nerve roots and compressed the canal. Both patients underwent resection of the hemivertebra with posterolateral instrumented fusion from L-2 to the pelvis. The female patient had a low-lying conus and underwent sectioning of the filum terminale. Both patients showed improvement in the ability to sit and lie flat and in bowel and bladder function after surgery. The authors describe their experience with 2 patients with similar, rare congenital bony deformities at the lumbosacral junction. To their knowledge, similar cases have not been previously reported.