Koya Kamikawa

Incidence of osteonecrosis associated with corticosteroid therapy among different underlying diseases: prospective MRI study

OBJECTIVES The purpose of this study was to clarify the incidence of (CS)-associated osteonecrosis among different underlying diseases and to evaluate the risk factors for steroid-associated osteonecrosis in a prospective MRI study. METHODS We prospectively used MRI to study 337 eligible underlying disease patients requiring CS therapy and succeeded in examining 1199 joints (hips and knees) in 302 patients with MRI for at least 1 year starting immediately after the onset of CS therapy (1-year follow-up rate of 90%). The underlying diseases included SLE in 687 joints (173 patients) and a variety of other rheumatological disorders in 512 joints (129 patients). RESULTS The incidence of osteonecrosis was significantly higher in SLE patients than in non-SLE patients (37 vs 21%, P = 0.001). Logistic regression analysis revealed that adolescent and adult patients had a significantly higher risk of osteonecrosis compared with paediatric patients [odds ratio (OR) = 13.2], that high daily CS dosage (>40 mg/day) entailed a significantly higher risk of osteonecrosis compared with the dosage of <40 mg/day (OR = 4.2), that SLE patients had a significantly higher risk of osteonecrosis compared with non-SLE patients (OR = 2.6) and that male patients had a significantly higher risk of osteonecrosis compared with female patients (OR = 1.6). CONCLUSION These findings suggest that the incidence of CS-associated osteonecrosis varies among different underlying diseases.

Changes in vertebral wedging rate between supine and standing position and its association with back pain: a prospective study in patients with osteoporotic vertebral compression fractures.

Study Design. Prospective consecutive series. Objective. To analyze supine and standing radiographs and the association of back pain using subjective pain criteria. Summary of Background Data. It has been considered that there is little correlation between the degree of collapse of the vertebral body and the level of pain. In previous studies, however, measurements have only been based on supine radiographs. Although there were 2 authors who reported the results of supine lateral and standing lateral radiographs in patients with thoracolumbar vertebral fractures, as far as we know, there has not been any detailed report concerning the correlation between radiologic findings using supine and standing lateral radiographs and back pain. Methods. We examined 100 consecutively treated patients, prospectively. Back pain and the supine and standing radiographs were assessed 1 month after injury. Changes in vertebral wedging rate (WR) from supine to standing position (&Dgr; WR) was reported by the following equation: &Dgr; WR = WR(standing) − WR(supine). Results. The median age of the cohort was 75 years (range, 60–89 years). The median VAS of back pain at supine position, at standing position, and when standing erect was 13, 33, and 41, respectively. The median wedging rate on the supine and standing radiographs were 28% and 37%, respectively (P < 0.001). There was a significant correlation between &Dgr; WR and back pain when standing erect (r = 0.79, P < 0.001). Conclusion. Changes in vertebral wedging rate between supine and standing position and its association with back pain may give a clue to the pathogenesis of pain from osteoporotic thoracolumbar vertebral compression fractures.

Facet joint orientation difference between cephalad and caudad portions: a possible cause of degenerative spondylolisthesis.

Study Design. A case-control study. Objective. To measure the orientation of the facet joints at both cephalad and caudad portions and to compare them between patients with degenerative spondylolisthesis (DS) and patients with lumbar spinal stenosis (LSS, controls). Summary of Background Data. Several radiologic studies have indicated a correlation between DS and an increased sagittal orientation of the facet joints. However, the orientation of the facet joints have only been measured on 1 axial cut of computed tomography scans and magnetic resonance imaging. Methods. Thirty-two patients with DS only at the L4–L5 level were assigned to group-1, and 28 patients with LSS without DS were assigned to group-2. Two computed tomography scans for the cephalad and caudad portions of the facet joint were made for L3–L4 and L4–L5 levels, respectively. Delta facet angle was defined as facet angle (cephalad)–facet angle (caudad). Results. Facet angles of the cephalad portion were more sagittally oriented (P < 0.001) than those of the caudad portion in group-1. The mean facet angle of the cephalad portion was 72° and that of the caudad portion was 57° at L4–L5. The mean facet angle of the cephalad portion at L4–L5 was greater (P = 0.001) in group-1 (72°) than in group-2 (62°). Delta facet angles were significantly greater in group-1 than in group-2. Mean delta facet angle was 15° in group-1 and 2° in group-2 at L4–L5 (P < 0.001), and 4° and 0°, respectively, at L3–L4 (P = 0.046). Conclusion. In this study, we confirmed that the cephalad portion of the facet joints were more sagittally oriented and that the caudad portion of the facet joints were more coronally oriented in patients with DS. These findings were observed not only at L4–L5 but also at the uninvolved L3–L4 level in patients with DS at the L4–L5 level.

Subsequent vertebral fractures following spinal fusion surgery for degenerative lumbar disease: a mean ten-year follow-up.

Study Design. Case-control study. Objective. To assess the long-term prevalence of vertebral fractures after lumbar spinal fusion with instrumentation. Summary of Background Data. The incidence of the adjacent and the nonadjacent, remote level subsequent vertebral fractures after lumbar spinal fusion is not well described in the literature. Methods. The study is a retrospective analysis of 100 consecutive patients of 55 years of age or older with spinal fusion for degenerative diseases between L1 and S1, and instrumentation for less than 4 segments. Patients with prevalent vertebral fractures defined at the time of surgery, or patients with secondary causes of osteoporosis were excluded. Mean follow-up period was 10.2 years (range, 7–14 years). Acute vertebral fractures were determined by magnetic resonance imaging and lateral spine radiographs. Results. Acute vertebral fractures were determined in 20 vertebrae in 14 (24%) of the 59 female patients, whereas 1 male patient (2%) had 1 vertebral fracture during the follow-up period. Eighteen of the 21 fractures occurred within 2 years of the spinal instrumentation surgery. Regarding time to fracture occurrence after surgery, adjacent level fractures occurred within 8 months, and remote level fractures occurred between 8 and 22 months after surgery. Conclusion. Postmenopausal female patients who underwent lumbar spinal instrumentation surgery were susceptible to develop subsequent vertebral fractures within 2 years after surgery. The greater the number of spinal segments between the fracture and the instrumentation was, the longer the time after surgery.

Transpedicular hydroxyapatite grafting with indirect reduction for thoracolumbar burst fractures with neurological deficit: A prospective study.

Background: The major problem after posterior correction and instrumentation in the treatment of thoracolumbar burst fractures is failure to support the anterior spinal column leading to loss of correction of kyphosis and hardware breakage. We conducted a prospective consecutive series to evaluate the outcome of the management of acute thoracolumbar burst fractures by transpedicular hydroxyapatite (HA) grafting following indirect reduction and pedicle screw fixation. Materials and Methods: Eighteen consecutive patients who had thoracolumbar burst fractures and associated incomplete neurological deficit were operatively treated within four days of admission. Following indirect reduction and pedicle screw fixation, transpedicular intracorporeal HA grafting to the fractured vertebrae was performed. Mean operative time was 125 min and mean blood loss was 150 ml. Their implants were removed within one year and were prospectively followed for at least two years. Results: The neurological function of all 18 patients improved by at least one ASIA grade, with nine (50%) patients demonstrating complete neurological recovery. Sagittal alignment was improved from a mean preoperative kyphosis of 17°to −2°(lordosis) by operation, but was found to have slightly deteriorated to 1° at final followup observation. The CT images demonstrated a mean spinal canal narrowing preoperatively, immediate postoperative and at final followup of 60%, 22% and 11%, respectively. There were no instances of hardware failure. No patient reported severe pain or needed daily dosages of analgesics at the final followup. The two-year postoperative MRI demonstrated an increase of one grade in disc degeneration (n = 17) at the disc above and in 11 patients below the fractured vertebra. At the final followup, flexion-extension radiographs revealed that a median range of motion was 4, 6 and 34 degrees at the cranial segment of the fractured vertebra, caudal segment and L1-S1, respectively. Bone formation by osteoconduction in HA granules was unclear, but final radiographs showed healed fractures. Conclusions: Posterior indirect reduction, transpedicular HA grafting and pedicle screw fixation could prevent the development of kyphosis and should lead to reliable neurological improvement in patients with incomplete neurological deficit. This technique does not require fusion to a segment, thereby preserves thoracolumbar motion.

A MINIMAL 10 YEARS FOLLOW-UP OF OSTEOPLASTIC HEMI-LAMINECTOMY IN PATIENTS WITH LUMBAR FORAMINAL DISC HERNIATION

Background: Osteoplastic hemi-laminectomy is able to alleviate the problems of procedures that require facet removal which poses a risk of instability in the treatment of lumbar foraminal disc herniation. Methods: Fourteen patients underwent osteoplastic hemi-laminectomy for the treatment of foraminal disc herniation with bi-radicular involvement. There were ten men and four women with a mean age of 39 years. The average length of follow-up was 12.3 years (10 to 14 years). The clinical results were assessed with the use of the Japanese Orthopaedic Association score (JOA score). Radiographic findings were analyzed on the basis of osteoarthritis of the facet joints and radiological instability. Regarding the surgical procedure, the midline of the spinous process and the pars interarticularis were cut in order to disarticulate the unilatelral lamina and inferior articular process. The central canal and lateral nerve root canal were exposed widely and visualized directly to allow neural decompression. Then the lamina was placed back into the original anatomical position, and fixed using a small cancellous screw. Results: The average operation time was 140 minutes and blood loss was 210 ml. The average JOA score (full score: 29) improved from 12 points preoperatively to 26 at the follow-up. Leg pain and low-back pain (full score: 3) improved from 0.4 to 2.8 and from 1.5 to 2.5, respectively. A significant correlation was not found between the presence of the osteoarthritis change of the facet joint and low back pain. Radiological instability was not observed in all patients at the follow up. Conclusions: Satisfactory results of osteoplastic hemi-laminectomy were maintained at a minimum of 10 years after surgery. The best indication for this procedure could be foraminal disc herniation involving two nerve roots. I N T E R N A T I O N A L S O C I E T Y F O R T H E S T U D Y O F L U M B A R S P I N E