Sakae Sato’s research while affiliated with University of the Ryukyus and other places

BACKGROUND Spinal reconstruction of an L5 osteoporotic vertebral fracture (OVF) is a demanding surgery because of the condition’s rarity, poor bone quality, and anatomical reasons. To date, there has been little debate regarding the surgical strategy for L5 OVF and effective osteoporosis treatment. The authors report L5 osteotomy and adjuvant romosozumab (ROMO) therapy for L5 OVF–induced spinal deformity. OBSERVATIONS A 73-year-old woman underwent lumbopelvic instrumentation and fusion from L3 to the pelvis, L5 osteotomy combined with unilateral posterior vertebral column resection (VCR), followed by expandable cage replacement and bone biopsy simultaneously. Histomorphometric analysis of the bone biopsy showed accelerated bone formation in the endocortical region of the spinous process. After surgery, her low back pain and leg pain improved with satisfactory global alignment. At the 2-year follow-up, lumbopelvic reconstruction achieved fusion, with minimal reciprocal change and no mechanical failure. The patient’s Oswestry Disability Index improved from 64% to 24%. L5 osteotomy combined with unilateral VCR and expandable cage replacement was a safe and effective technique in this case. LESSONS This technique can provide both greater restoration of lower lumbar lordosis and pelvic tilt with fusion. Moreover, adjuvant ROMO therapy has the potential to prevent osteoporosis-related complications. https://thejns.org/doi/10.3171/CASE24633

21 patients who underwent spinal fusion using pedicle screws for lumbar canal stenosis were reviewed. There were 11 males and 10 females. The mean age at surgery was 61 years and the mean follow-up period was 28 months. Degenerative spondylolisthesis was found in 18 patients and degenerative lumbar canal stenosis with antero-posterior instability in 3 patients.The improvement rate of JOA score was 73% and bony union rate was 95%. Low back pain was improved in 12 (63%) out of 19 patients, and intermittent claudication in 17 (81%) out of 21 patients. Leg symptom, however, remained in 14 (70%) out of 20 patients. Numbness mainly deteriorated the leg symptoms.Instrumentation and bone graft were added in the segments adjacent to fusion for 2 patients: a 64-year-old female showing pedicle screws pull-out and graft bone collapse due to osteoporosis, and a 69-year-old male developing new scoliosis on the adjacent segment which had been decompressed without fusion. Attention should be paid to using pedicle screws for osteoporotic patients and to decompression without fusion for segments adjacent to fusion.

We report the effectiveness of instrumentation for aggravated thoracic myelopathy after laminectomy for ossification of the posterior longitudinal ligament (OPLL) and ossification of the yellow ligament (OYL). A 44-year-old woman with thoracic OPLL and OYL underwent laminectomy of T7-T11 at another hospital showed aggravation of myelopathy: muscle weakness and sensory loss developed in the sitting position, which however improved in the supine position. Radiological analysis showed that the kyphotic angle of T6-T12 was 6 degrees in the sitting position but it increased to 18 degrees in the supine position. Therefore posterior element defect due to laminectomy as well as obesity seemed to aggravate myelopathy. We corrected kyphosis using ISOLA and the kyphotic angle decreased corrected to 9 degrees. She became ambulatory with a cane after the surgery. Three months later we added anterior decompression and fusion of T7 to T9, and she could walk without any support. We recommend addition of posterior instrumentation after laminectomy in such obese patients with thoracic OPLL.

To study the usefulness of posterior fusion using pedicle screws, 32 patients (average age at surgery 37.2 years, average follow-up 29 months) with lumbar disc degenerative disease except olisthesis, lysis, and spinal canal stenosis were reviewed.All patients were divided into 4 groups: 14 with neural compression (NC) without previous lumbar surgery (PLS) (Group 1), 5 with no NC without PLS (Group 2), 9 with NC with PLS (Group 3), 4 with no NC with PLS (Group 4). JOA score and reinstatement for physical work were evaluated in these groups. The recovery rate of low back pain score ranged from 50% to 66%. The recovery rate of leg symptom score was higher in Group 1 than in Group 3 and Group 4. 14 out of 17 patients (82%) who had physical work returned to the same work afterr operation: the reinstatement rate was 100% in Group 1 and Group 3, 60% in Group 2, and 50% in Group 4.The height of the disc adjacent to fusion and loadotic angle of fusion area were analyzed in lateral radiographs to compare PLIF with PLF. There were no significant differences between the 2 procedures. More than 5mm of loadosis was lost at follow-up in 2 out of 4 patients who had underwent two-level PLF.

Operative cases in thoraco-lumbar fracture-dislocations were investigated. Nine males underwent surgical reduction, decompression and posterior instrumentations using ISOLA in 7 patients and VSP in 2 from June 1993 to July 1998. The age at the surgery ranged from 24 to 49 years old (average 33 years old) and follow-up period from 4 months to 65 months (average 17 months). The dislocated vertebrae ranged from T9 to L2 and 3.4 vertebrae on average were included into fusion area. Four patients underwent urgent operations and 5 patients elected operations.The duration of bed rest averaged 2 weeks. Six patients represented complete paraplesia preoperatively and no one improved postoperatively. Three patients with incomplete paraparesis improved completely (2 patients D→E, 1 patient B→E). After surgery the mean kyphotic angle before, justafter, at follow-up were 12°, 0°, and 4° respectively. Therefore good reduction was achieved and the correction loss was small. Three patients complained of persistent girdle pain of the torso but there was no relation with the correction loss of the kyphosis after surgery.

The purpose of this study is to evaluate the clinical outcome of osteoplastic laminectomy applied to space occupying lesions in the spinal canal. Osteoplastic laminectomy was performed in 14 patients, of which 4 were diagnosed with spinal cord tumor, 3 with cauda equina tumor, 3 with lumbar disc herniation, 1 with extradural arachnoid cyst, 1 with extradural granulation, 1 with arterio-venous malformation, and 1 with L3 burst fracture. Operative procedures were 1) osteotomy of the bilateral interarticular parts and spinous processes using a threadwire saw, 2) removal of the lamina, 3) resection of the intracanal lesion, and 4) fixation of the posterior element with lag screws.The average recovery rate of the clinical score was 29% in 2 cases of thoracic myelopathy, and 67% in 12 cases of lumbar symptoms. The lesions expanding up to 107% of the longitudinal diameter or 123% of the lateral diameter in the spinal canal could be resected under an excellent visual field. Oblique radiographs of the lag screws showed that congruity of the osteotomy site strongly correlated (p=0.03) to positioning all threads in the anterior part. The screw tips in L5 were loosened because of osteoporosis and the lowest mobile segment.

Neurinoma is the most common spinal cord tumor. However neurinoma with large cystic changes are rare. We experienced two cases of this condition in the lumbar spine: A 53-year-old male suffering from low back pain and bilateral buttock and thigh numbness; and a 40-year-old female complaining of low back and left lower limb pain and pollakisuria. The MR images of both cases showed an intradural tumor with large cystic change, which represented low signal in T1-weighted images and high signal in T2-weighted images. In the contrast MR images of case 2 the cyst wall was clearly enhanced with Gd-DTPA. Both tumors were removed surgically and pathologically diagnosed as Antoni-B type neurinoma.No evidence of any postoperative neurological defect was shown.Contrast-enhaced MR images should be taken to differentiate between a cystic neurinoma and an arachnoidal cyst.

10 females with vertebral fracture and kyphosis deformity due to osteoporosis were retrospectively studied following operative treatment. Their average age was 68 years (46 to 77 years) at the time of operation. The average follow-up was 10 months. All patients had neurological disorder (4: thoracic myelopathy, 5: cauda equina syndrome, 1: myelopathy and cauda eguina syndrome) while 6 had non-ambulatory paraparesis. They were treated by posterior instrumentation and spinal fusion, and an additional anterior decompression followed by A-W glass ceramic strut graft in 5 with spinal canal encroachment of fracture fragments. Urinary disturbance in 6 patients disappeared, intermittent claudication in 3 disappeared (2) or improved (1), and low back pain in 10 disappeared (4) or improved (6). The 6 non-ambulatory cases were able to walk with support except for a rheumatoid arthritis patient. Instrumentation was useful in relieving back pain with early mobilization. The correction rate of kyphosis was, however, 50% for insufficiently balanced spine, showing no correlation with the improvement of clinical symptoms. Use of hooks instead of screws for secure anchorage in the bone, supplemental spinal osteotomy for greater correction, and more precise instrumentation for well-balanced spine are required.

We studied 23 cases (17 males, 6 females) with suppurative spondylitis to find out the characteristics which affect the clinical course. Two cervical cases and 11 thoracoo-lumbar cases recuperated with intravenous antibiotics, however, four cervical cases and six thoraco-lumbar cases needed surgery after antibiotic administration. Thoraco-lumbar cases aged under 14 years could be treated conservatively. The surgical cases revealed the following characteristics: palsy due to kyphotic deformity of the cervical spine, and long-standing (>8 weeks)/recurrent inflammation in the thoraco-lumbar spine despite antibiotic admimistration. Regarding the area of osteolysis shown on radiographs and high intensity areas in MR images, significant differences were not seen between conservatively and surgically treated cases at any spinal level. High intensity area in T2 weighted images extended to the whole body of the cervical spine.