A fourteen-year-old boy presented with a sixteen-month history of
low-back pain that worsened with activity. He reported no history of trauma,
weight loss, fevers, chills, sweats, or night pain. He had no neurological
symptoms. Prior to presentation, he had undergone chiropractic treatments that
had been ineffective for pain relief and he had been seen by twelve different
physicians for evaluation of his complaints. The medical and surgical
histories were unremarkable. The patient was taking no medications and had a
negative family history for scoliosis and other vertebral deformities. The use
of nonsteroidal anti-inflammatory medications had not resulted in substantial
pain relief.
Physical examination revealed a left trunk shift and waist asymmetry. In
addition, the iliac crest and shoulder on the right side were lower than those
on the left side. The patient had hyperlordosis of the lumbar spine and
markedly decreased forward and lateral bending as well as tender paraspinal
muscles on the concave side of a right lumbar hump. He was only able to
forward flex approximately 10° with the knees extended. Neurological
examination revealed normal findings, including superficial abdominal reflexes
and a negative straight-leg-raising test for both lower extremities. The
popliteal angle (measured as the lack of full knee extension with the hips
flexed to 90°) was 20° on the right side and 30° on the left.
Plain radiographs showed a 25° right lumbar curve from the second
lumbar vertebra to the sacrum, with coronal decompensation of 7 cm to the left
(Figs. 1-A and 1-B). The left
pedicle of the fourth lumbar vertebra was obscured. A bone scan showed
increased activity near the left pedicle of the fourth lumbar vertebra
(Fig. 2). A computed
tomographic scan showed an osseous mass with an apparent nidus in the left
pars interarticularis of the fourth lumbar vertebra
(Fig. 3). The preliminary
diagnosis was an osteoid osteoma of the left pars interarticularis of the
fourth lumbar vertebra.
Because of the pain, markedly decreased motion, and spinal deformity, the
patient was managed with an en bloc resection of the left pars
interarticularis of the fourth lumbar vertebra. The lesion extended from the
base of the left fourth lumbar pedicle to the superior margin of the left
fourth lumbar inferior facet. The resection was performed from the base of the
pedicle to the superior margin of the inferior facet. With use of
intraoperative radiographs, the entire nidus was identified within the
resected specimen (Fig. 4). An
autogenous bone graft from the posterior iliac crest was then harvested
through the same incision. A corticocancellous graft was fashioned to fit the
defect at the site of the resected pars interarticularis. A multiaxial pedicle
screw was inserted into the left fourth lumbar pedicle. It was combined with
an oblique superiorly directed laminar hook that was inserted caudad to the
remaining left fourth lumbar infralaminar region along with a contoured
connecting rod. The hook was then compressed on the rod, across the newly
reconstructed pars interarticularis, thereby securing the bone graft but not
fusing the facet joint. Intraoperative plain radiographs showed excellent
positioning of the instrumentation. Throughout the procedure, there were no
changes in somatosensory spinalcord monitoring or appropriate intraoperative
electromyographic stimulation data.
Histologic examination showed osteoid lined with plump osteoblasts and
vascularized connective tissue, which, along with the size of the lesion, were
consistent with the diagnosis of an osteoid osteoma. Postoperatively, the pain
resolved and the patient was placed in a thoracolumbar spinal orthosis. At
five weeks, the incision was healed, use of the orthosis was discontinued, and
a home physical therapy program designed to improve hamstring flexibility was
initiated. Twelve weeks after surgery, the trunk alignment had returned to
midline. The patient progressed to normal activities with a 10 to 15-lb (4.5
to 6.8-kg) weight-lifting restriction. Seven months postoperatively,
radiographs showed minimal residual deformity and the patient was permitted to
return to full activities. At the time of the latest follow-up, three years
after surgery, the patient was asymptomatic and there was no clinical or
radiographic evidence of recurrence of the scoliosis
(Figs. 5-A and 5-B).