Shinichi Numazawa

Treatment of extensive cranial bone defects using computer-designed hydroxyapatite ceramics and periosteal flaps

We performed cranioplasty using hydroxyapatite ceramics and periosteal flaps in three patients with extensive cranial bone defects. These defects were left after post-brain surgery infection forced the removal of cranial bone. Hydroxyapatite ceramics made by using computer-aided design from three-dimensional computed tomographic image data were implanted in these patients. The defects were relatively large (the largest was 16.5 x 7.5 cm) and had a high degree of curvature. Three pieces were required in one patient, although one piece was sufficient in the other two patients. The surgical technique consisted of removal of the epidural granulation tissue, exposure of the cranial bone defect site, and shaping of the hydroxyapatite ceramics to fit the defect entirely, followed by the implantation of the hydroxyapatite ceramics. In anticipation of induction of the bone to hydroxyapatite, we covered the hydroxyapatite ceramics with periosteal flaps of cranial bones; however, based on only these three patients, our knowledge of the ossification-promoting effect is incomplete. More clinical cases should be investigated to evaluate further the clinical efficacy of this method for treatment. As we have reported here, the treatment of cranial bone defects by using computer-designed hydroxyapatite ceramics and a periosteal flap is safe and highly effective.

Recapping hemilaminoplasty for spinal surgical disorders using ultrasonic bone curette

Objective: The authors present a novel method of the recapping hemilaminoplasty in a retrospective study of patients with spinal surgical disorders. This report describes the surgical technique and the results of hemilaminoplasty using an ultrasonic bone curette. The aim of this study was to examine the safety and effectiveness of the hemilaminoplasty technique with ultrasonic bone curette. Methods: Between April 2003 and July 2011, 33 patients with various spinal diseases (17 spinal tumors, 5 dural arteriovenous fistulas, 3 syringomyelia, 2 sacral perineural cysts, and 2 arachnoid cysts) were treated microsurgically by using an ultrasonic bone curette with scalpel blade and lightweight handpiece. The ultrasonic bone curette was used for division of lamina. After resection of the lesion, the excised lamina was replaced exactly in situ to its original anatomic position with a titanium plate and screw. Additional fusion technique was not required and the device was easy to handle. All patients were observed both neurologically and radiologically by dynamic plain radiographs and computed tomography (CT) scan. Results: The operation was performed successfully and there were no instrument-related complications such as dural laceration, nerve root injury, and vessels injury. The mean number of resected and restored lamina was 1.7. CT confirmed primary bone fusion in all patients by 12 months after surgery. Conclusion: The ultrasonic bone curette is a useful instrument for recapping hemilaminoplasty in various spinal surgeries. This method allows anatomical reconstruction of the excised bone to preserve the posterior surrounding tissues.

Spinous process plate (S-plate) fixation after posterior interbody fusion for lumbar canal stenosis due to spondylolisthesis.

In operations for lumbar canal stenosis due to spondylolisthesis with instability, internal fixation of the lumbar spine has been attempted after lumbar posterior decompression, as lumbar posterior decompression would worsen the instability and thus limit functional improvement postoperatively. In these cases, we have been performing lumbar posterior decompression followed by posterior lumbar interbody fusion (PLIF) with pedicle screws (PSs). However, cases where the patient has osteoporotic bone carry a high risk of complications such as backing out of screws and fracture of pedicles after performing PS fixation. In such cases, we use a spinous process plate (S-plate; Kisco DIR, Osaka, Japan) instead of PSs (Fig. 1). In this paper, we describe our surgical strategy for lumbar spondylolisthesis with instability using the S-plate and present our results for this procedure. Clinical materials and methods

Minimally invasive central corpectomy for ossified posterior longitudinal ligament in the cervical spine

Minimally invasive central corpectomy (MICC) for cervical segmental ossified posterior longitudinal ligament (OPLL) is described. The procedure of MICC includes upper- or lower-half central corpectomy of the involved cervical spine, transdiscal decompression of the adjacent disc level, dissection and partial removal of the OPLL, removal of the OPLL behind the vertebral body via these windows, and fusion with cylindrical titanium cages. Anterior plate fixation is not necessary. From January 2008 to December 2009 we surgically treated three patients with cervical OPLL by MICC. All three patients showed remarkable improvement of their symptoms within a few days after the operation. No neurological or radiological complication was observed during that period. MICC is beneficial in avoiding complete corpectomy and long fusion, usage of an anterior plate, and usage of a large external orthosis. MICC also reduces the risk of postoperative esophageal perforation due to a screw backing out of the plate.