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Mikinobu Takeuchi, Norimitsu Wakao, Mitsuhiro Kamiya, Aichi Niwa, Koji Osuka and Masakazu Takayasu

In this paper the authors report the case of a patient with ossification of the posterior longitudinal ligament (OPLL) below the axial vertebra (C-2) at the kyphotic cervical spine, with an atlas vertebra (C-1) posterior arch that compressed the spinal cord with the head in a pathognomonic position, similar to a protruded position. This condition appears to be very rare. The morphological findings between the kyphotic cervical spine and OPLL, the upper occipitocervical junction, and the protruded-head position are discussed. A 40-year-old man presented with severe pain radiating to both legs when he yawned, sneezed, or extended his jaw (a protruded-head position). A kyphotic cervical spine with OPLL below C-2 was observed using CT and radiography, yet sagittal T2-weighted MRI failed to identify abnormal findings in a neutral or extension position, except for a slight cervical canal stenosis. However, in a pathognomonic protruded-head position, sagittal T2-weighted MRI showed a C-1 posterior arch that severely compressed the spinal cord at the upper cervical level. Therefore, the authors believe that the severe pain radiating to both legs was caused by a spinal canal stenosis due to a C-1 posterior arch impingement. The C-1 posterior arch was resected, and after the surgery, the patient indicated that the intolerable pain had disappeared. In conclusion, in patients with OPLL and a kyphotic cervical spine, the authors propose that the pathognomonic protruded position is valuable for estimating disrupted compensatory mechanisms at the upper cervical junction.

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Masakazu Takayasu, Teruhide Takagi, Toshihisa Nishizawa, Koji Osuka, Takehiko Nakajima and Jun Yoshida

Object. The authors report a simple method for bilateral open-door cervical expansive laminoplasty in which hydroxyapatite (HA) spacers are secured by titanium screws. A biomechanical study was also conducted to confirm the strength of the screw fixation.

Methods. A unilateral posterior approach was used to allow preservation of the posterior supporting elements (the posterior tension band) until the laminae were cut at the base. A bilateral open-door expansive laminotomy was then performed in standard fashion. Appropriate-sized HA spacers were selected, held with a specially designed holder, and placed between the split laminae. The screw holes were made in the laminae along the direction of the screw holes in the spacer, and two screws were inserted ventrolaterally to the laminae, resulting in instantaneous fixation. This procedure was performed in 15 patients; clinical results were successful, and there were no significant intraoperative complications. Follow-up radiological studies revealed no evidence of displacement of the spacers or screw backout. The screw artifacts observed on magnetic resonance imaging were minimal, allowing evaluation of the cervical spinal cord. The sagittal alignment of the cervical spine was well preserved. In the biomechanical studies the authors found that the screw fixation was of satisfactory strength, compared with other methods of fixation.

Conclusions. Bilateral open-door cervical expansive laminoplasty in which HA spacers are secured by titanium screws is a simple and quick method that yields sufficient fixation strength.