Postoperative translation of the upper instrumented vertebra in thoracic adolescent idiopathic scoliosis.

OBJECTIVEThe aim of this retrospective study was to analyze the influence of upper instrumented vertebra (UIV) translation from the C7 plumb line (C7PL) on the long-term postoperative results of patients with main thoracic (MT) adolescent idiopathic scoliosis (AIS).METHODSTwenty-five patients had been treated surgically for AIS with a Lenke type 1 curve and had been followed up for a mean period of 18.2 years. Radiographic parameters, pulmonary function measurements, and clinical outcomes were compared between the patients (n = 15) with UIV translation < 20 mm and those (n = 10) with UIV translation ≥ 20 mm at the final follow-up. Correlations between UIV translation and radiographic or pulmonary function parameters were analyzed.RESULTSPatients with ≥ 20 mm UIV translation at the final follow-up had a significantly larger preoperative UIV translation than that in the patients with < 20 mm UIV translation at follow-up. The former group also had a significantly lower correction rate of the MT curve, higher chest cage ratio, and lower radiographic shoulder height (p = 0.01, 0.005, and 0.025, respectively) at the final follow-up. The Scoliosis Research Society (SRS)-30 Questionnaire scores were equivalent between the two groups. Correlation analysis showed that the following parameters were significantly associated with UIV translation: MT curve correction rate (r = -0.481, p = 0.015), chest cage ratio (r = 0.673, p < 0.001), and percent-predicted forced expiratory volume in 1 second (r = -0.455, p = 0.033).CONCLUSIONSThe UIV translation should be considered an important factor that influences postoperative results. In MT AIS patients whose preoperative upper end vertebra (UEV) is distant from the C7PL, the UIV should be selected above the UEV to prevent large UIV translation at the postoperative follow-up.

Selection of the upper vertebra to be instrumented in the treatment of thoracolumbar and lumbar adolescent idiopathic scoliosis by anterior correction and fusion surgery using dual-rod instrumentation: a minimum 12-year follow-up study.

BACKGROUND CONTEXT: Consensus regarding the optimal upper vertebra to be instrumented during surgical treatment of Lenke 5C thoracolumbar and lumbar adolescent idiopathic scoliosis (AIS) remains limited. PURPOSE: This study aimed to assess whether a short fusion strategy is appropriate for correction of a Lenke 5C AIS curve by anterior correction and fusion surgery using dual-rod instrumentation. STUDY DESIGN: This study design used retrospective comparative analysis of a prospectively collected, consecutive, non-randomized series of patients at a single institution. PATIENT SAMPLE: Thirty consecutive patients with Lenke 5C AIS treated with anterior correction and fusion surgery using dual-rod instrumentation were included. OUTCOME MEASURES: Patient demographics, radiographic measurements, and Scoliosis Research Society-22 questionnaire (SRS-22) scores were the outcome measures for this study. METHODS: Thirty patients were treated surgically for AIS with a Lenke 5C curve (mean age, 14.4 years [11-19 years)]) and followed up for a mean period of 17.2 years (12-23 years). Radiographical parameters and clinical outcomes were compared between patients treatment with the end vertebra (EV) instrumented (n=14) and those treated by short fusion (S group) with instrumentation starting at the vertebra one level caudal to the EV (n=16 patients). There were no study-specific biases related to conflicts of interest. RESULTS: In the EV group, a mean preoperative Cobb angle of 56° was corrected to 5° after surgery and to 8° at the final follow-up. In the S group, a mean preoperative Cobb angle of 55° was corrected to 10° after surgery and 14° at the final follow-up. The mean correction rate at the final follow-up was significantly lower in the S group (74%) than in the EV group (86%; p=.020). The coronal and sagittal balance, thoracic kyphosis, lumbar lordosis, and clinical outcomes evaluated using SRS-22 did not differ between the two groups. CONCLUSIONS: The short fusion strategy, which involves instrumentation of the vertebra one level caudal to the upper EV, can be considered as an alternative to the conventional strategy, which includes instrumentation of the upper EV, for treating Lenke 5C curves via anterior spinal fusion.

Anterior decompression and strut graft versus posterior decompression and pedicle screw fixation with vertebroplasty for osteoporotic thoracolumbar vertebral collapse with neurologic deficits.

BACKGROUND CONTEXT: With the increase of the elderly population, osteoporotic vertebral fractures have been frequently reported. Surgical intervention is usually recommended in osteoporotic vertebral collapse with neurologic deficits. However, very few reports on surgical interventions exist. PURPOSE: To compare surgical results of anterior and posterior procedures for treating osteoporotic thoracolumbar vertebral collapse with sustained neurologic deficits. STUDY DESIGN: Retrospective comparative study. PATIENT SAMPLE: Fifty patients who sustained osteoporotic thoracolumbar vertebral collapse with neurologic deficits were treated either by anterior decompression and strut graft (n=32) or by posterior decompression and pedicle screw fixation with vertebroplasty (n=18). OUTCOME MEASURES: Incidence of complications, sagittal Cobb angle, spinal canal encroachment, and Japanese Orthopedic Association score. METHODS: The authors retrospectively reviewed the results of a consecutive series of patients undergoing anterior decompression and strut graft or posterior decompression and pedicle screw fixation with vertebroplasty for osteoporotic thoracolumbar vertebral collapse with neurologic deficits. Operative notes, clinical charts, and radiographs were analyzed. RESULTS: Operative time was similar between the groups, but intraoperative blood loss was significantly lower in the posterior group. All patients showed neurologic recovery. No significant difference was observed in the neurologic improvement, kyphosis correction angle, and loss of correction. Perioperative respiratory complications were found in 11 patients (34%) in the anterior group. In the anterior group, early posterior reinforcement was required in patients with very low bone density below 0.60 g/cm(2) and/or in those with three segments of instrumentation for two vertebral collapses. Posterior group patients did not undergo additional surgery. CONCLUSIONS: Anterior reconstruction for osteoporotic vertebral collapse is significant because anterior elements, particularly those at the thoracolumbar junction, play a major role in load bearing. However, difficulties arise when anterior reconstruction is performed in cases with very low bone density and in those with multiple vertebral collapse.

Long-term outcomes of anterior dual-rod instrumentation for thoracolumbar and lumbar curves in adolescent idiopathic scoliosis: a twelve to twenty-three-year follow-up study.

BACKGROUND: Anterior spinal fusion with instrumentation is used for the treatment of thoracolumbar/lumbar scoliosis. The aim of this long-term, retrospective, hospital-based cohort study was to determine the outcomes of anterior dual-rod instrumentation in a consecutive series of patients with thoracolumbar/lumbar adolescent idiopathic scoliosis managed by a single surgeon at a single institution. METHODS: A consecutive series of thirty-two patients with Lenke type-5C thoracolumbar/lumbar adolescent idiopathic scoliosis were included. Outcome measures included patient demographics, radiographic measurements, adjacent-segment degeneration, pulmonary function, and Scoliosis Research Society outcome instrument (SRS-30) scores. Perioperative and postoperative complications were recorded. RESULTS: Thirty patients were followed for a mean of 17.2 years (range, twelve to twenty-three years). The mean thoracolumbar/lumbar Cobb angle correction rate and correction loss at the time of the latest follow-up were 79.8% and 3.4°, respectively. The average percent-predicted forced vital capacity and forced expiratory volume in one second were 91.8% and 81.8%, respectively. The average total SRS-30 score was 4.2. Mild degeneration below the fusion mass was observed in 23% of the patients. No instrumentation failure, pseudarthrosis, surgical site infection, or clinically relevant neurovascular complications were observed. Two patients required surgical revision with posterior spinal instrumentation, one because of subjacent disc wedging and the other because of progression of the thoracic curve deformity. CONCLUSIONS: Radiographic findings, pulmonary function, and clinical measures were satisfactory at the time of follow-up, at a minimum of twelve years. Anterior dual-rod instrumentation remains a useful surgical treatment for Lenke type-5C thoracolumbar/lumbar adolescent idiopathic scoliosis.

Long-term outcomes of anterior spinal fusion for treating thoracic adolescent idiopathic scoliosis curves: average 15-year follow-up analysis.

STUDY DESIGN: Retrospective review. OBJECTIVE: To assess the long-term outcomes of anterior spinal fusion (ASF) for treating thoracic adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA: Although ASF is reported to provide good coronal and sagittal correction of the main thoracic (MT) AIS curves, the long-term outcomes of ASF is unknown. METHODS: A consecutive series of 25 patients with Lenke 1 MT AIS were included. Outcome measures comprised radiographical measurements, pulmonary function, and Scoliosis Research Society outcome instrument (SRS-30) scores (preoperative SRS-30 scores were not documented). Postoperative surgical revisions and complications were recorded. RESULTS: Twenty-five patients were followed-up for 12 to 18 years (average, 15.2 yr). The average MT Cobb angle correction rate and the correction loss at the final follow-up were 56.7% and 9.2°, respectively. The average preoperative instrumented level of kyphosis was 8.3°, which significantly improved to 18.6° (P = 0.0003) at the final follow-up. The average percent-predicted forced vital capacity and forced expiratory volume in 1 second were significantly decreased during long-term follow-up measurements (73% and 69%; P = 0.0004 and 0.0016, respectively). However, no patient had complaints related to pulmonary function. The average total SRS-30 score was 4.0. Implant breakage was not observed. All patients, except 1 who required revision surgery, demonstrated solid fusion. Late instrumentation-related bronchial problems were observed in 1 patient who required implant removal and bronchial tube repair, 13 years after the initial surgery. CONCLUSION: Overall radiographical findings and patient outcome measures of ASF for Lenke 1 MT AIS were satisfactory at an average follow-up of 15 years. ASF provides significant sagittal correction of the main thoracic curve with long-term maintenance of sagittal profiles. Percent-predicted values of forced vital capacity and forced expiratory volume in 1 second were decreased in this cohort; however, no patient had complaints related to pulmonary function.

Role of major spine surgery using Kaneda anterior instrumentation for osteoporotic vertebral collapse.

STUDY DESIGN: A retrospective study. OBJECTIVES: To investigate the clinical and radiographic results of spinal reconstruction using Kaneda anterior spinal instrumentation for osteoporotic vertebral collapse. SUMMARY OF BACKGROUND DATA: Recent advances in osteoporotic vertebral fracture treatment including kyphoplasty changes the role of major surgery for these pathologies. However, osteoporotic vertebral collapse with neurologic compromise remains requiring surgical decompression and reconstruction. METHODS: Thirty-one consecutive patients who underwent anterior spinal reconstruction for osteoporotic vertebral collapse with neurologic deficits were reviewed retrospectively. Twenty-six patients had single vertebral collapse and 5 had multiple lesions. They were 10 males and 21 females with mean age of 71 years. Mean follow-up period was 57 months. For anterior column support, iliac bone graft was used in 1 patient, cylindrical titanium cages in 12, and bioactive ceramic spacers in 18 patients. Kaneda anterior instrumentation was used in all the patients. Radiographic and clinical assessments were performed preoperatively and at the final follow-up. RESULTS: All the patients showed neurologic recovery. Visual analog scales (0 to 10) of low back pain and sciatic pain were 5.8 and 4.2 before surgery, and 2.1 and 0.6 at the final follow-up, respectively. Mean kyphosis of operative levels was 31 degrees before surgery, and improved to 13 degrees immediately after surgery and 21 degrees at the final follow-up. Posterior reinforcement was required in 6 patients (19%), who had severe osteoporosis and/or underwent multilevel corpectomies. Solid fusion was achieved in all patients at the final follow-up. CONCLUSIONS: The current study demonstrated the advantages of anterior spinal reconstruction in osteoporotic vertebral collapse: (1) safe and reliable decompression could be performed, and (2) 80% of patients were successfully treated with anterior spinal reconstruction alone. However, patients with multilevel corpectomies and/or severe osteoporosis highly required posterior reinforcement.

Development of a clinical diagnosis support tool to identify patients with lumbar spinal stenosis.

No clinical diagnostic support tool can help identify patients with LSS. Simple diagnostic tool may improve the accuracy of the diagnosis of LSS. The aim of this study was to develop a simple clinical diagnostic tool that may help physicians to diagnose LSS in patients with lower leg symptoms. Patients with pain or numbness of the lower legs were prospectively enrolled. The diagnosis of LSS by experienced orthopedic specialists was the outcome measure. Multivariable logistic regression analysis identified factors that predicted LSS; a simple clinical prediction rule was developed by assigning a risk score to each item based on the estimated beta-coefficients. From December 2002 to December 2004, 104 orthopedic physicians from 22 clinics and 50 hospitals evaluated 468 patients. Two items of physical examination, three items of patients' symptom, and five items of physical examination were included in the final scoring system as a result of multiple logistic regression analysis. The sum of the risk scores for each patient ranged from -2 to 16. The Hosmer-Lemeshow statistic was 11.30 (P = 0.1851); the area under the ROC curve was 0.918. The clinical diagnostic support tool had a sensitivity of 92.8% and a specificity of 72.0%. The prevalence of LSS was 6.3% in the bottom quartile of the risk score (-2 to 5) and 99.0% in the top quartile (12 to 16). We developed a simple clinical diagnostic support tool to identify patients with LSS. Further studies are needed to validate this tool in primary care settings.

Clinical effect of bisphosphonate and vitamin D on osteoporosis: reappraisal of a multicenter double-blind clinical trial comparing etidronate and alfacalcidol.

As inhibitors of bone resorption, bisphosphonates and vitamin D derivatives have been extensively used for the treatment of osteoporosis in various parts of the world, but the clinical effects of these two groups of agents have rarely been compared in detail. A multicenter, prospective, double-blind controlled study was started comparing the effects of etidronate and alfacalcidol (1-alpha-hydroxycholecalciferol) in 414 patients with established osteoporosis from 36 centers. Among these patients, 135 were given 400 mg etidronate daily at bedtime for 2 weeks followed by 10 weeks off treatment, and this cycle was repeated four times along with a placebo indistinguishable from the alfacalcidol capsule daily throughout the 48 weeks of study (Group A, High Dose Etidronate Group). In 133 patients, 200 mg etidronate was used instead of 400 mg (Group B, Low Dose Etidronate Group). In 138 patients, 1 microg alfacalcidol was given daily throughout the 48-week study period along with a placebo indistinguishable from the etidronate tablet in four separate periods of 2 weeks (Group C, Control Group). Dual-energy X-ray absorptiometry of the lumbar spine (L2-L4) was performed before the beginning of the study and every 12 weeks thereafter. Changes in spinal deformity were also assessed based on the lateral thoracic and lumbar spine X-ray films taken before and after the study. The lumbar spine bone mineral density (BMD) changes were +3.4% +/- 0.6% (mean +/- SEM) in Group A, +2.4% +/- 0.5% in Group B, and -0.5% +/- 0.4% in Group C, the former two being significantly higher than the last. New occurrence of spinal compression fracture was also significantly reduced in Group A compared to Group C. In patients without previous fracture at entry, incident fracture was 10.2% in Group C, but 0% in Groups A and B. In patients with prevalent fracture at entry, corresponding figures were 21.5% (Group C), 12.0% (Group A), and 13.2% (Group B), respectively. Alfacalcidol maintained lumbar spine BMD, preventing a decrease for 48 weeks, and etidronate significantly increased it further, demonstrating its usefulness in the treatment of established osteoporosis.

Radiological risk factors of pseudoarthrosis and/or instrument breakage after PLF with the pedicle screw system in isthmic spondylolisthesis.

OBJECTIVE: Several studies have reported favorable results of posterolateral fusion (PLF) with pedicle screw systems (PSs) for isthmic spondylolisthesis. However, the best indication and limitations of this method still remain unclear. The present study aimed to analyze the radiological risk factors of pseudoarthrosis and/or instrumentation failure after PLF with PSs in isthmic spondylolisthesis, and to determine the limitations of this method. METHODS: The study group comprised of 101 patients with isthmic spondylolisthesis who underwent PLF with PSs. Follow-up was performed for more than 5 years. Statistical analyses with multivariate logistic regression models were used to identify risk factors of pseudoarthrosis and/or instrument failures associated with PLF with PSs. RESULTS: Average follow-up was 8 years. Fusion rate was 95%. There were instrument breakage in 6 patients, and pseudoarthrosis in 5. Statistical analysis with a logistic regression model revealed that preoperative % disc height (odds ratio: 3.60 per 10%, P<0.01) and slip angle (odds ratio: 4.48 per 10 degrees kyphosis, P<0.05) were the most crucial risk factors of pseudoarthrosis and/or instrument breakage when performing PLF for isthmic spondylolisthesis. CONCLUSIONS: In conclusion, PLF with PSs provided satisfactory results with high fusion rate. However, there were complications including pseudoarthrosis or instrument breakage in specific conditions. Preserved disc height and presence of segmental kyphosis were risk factors of these complications. Statistically, % disc height within 20% without segmental kyphosis was the best indication for PLF with PSs.

Comparative study of radiographic disc height changes using two different interbody devices for transforaminal lumbar interbody fusion: open box vs. fenestrated tube interbody cage.

STUDY DESIGN: Retrospective comparative study of the postoperative subsidence of two interbody devices following posterior or transforaminal lumbar interbody fusion (PLIF/TLIF) for degenerative spondylolisthesis of the lumbar spine. OBJECTIVE: To assess certain radiograph characteristics of PLIF/TLIF using two interbody fusion devices at L4-L5. SUMMARY OF BACKGROUND DATA: PLIF can achieve spinal stabilization with vertebral body support and direct neural decompression. Although various interbody devices have been used in PLIF procedures, no radiographic studies have compared the load-bearing capabilities of open box and fenestrated tube interbody cages. METHODS: Seventy-five patients who underwent one-level PLIF in the L4-L5 [corrected] segment for degenerative spondylolisthesis were retrospectively reviewed with a minimum 2-year follow-up. Fenestrated tube (Group FT: n = 30 [corrected]) or open box (Group OB: n = 45 [corrected]) cages were used for the PLIF procedure. The following radiographic parameters were evaluated to compare the load-bearing capabilities: disc space height (DH); percent increase and decrease of disc height (% IDH and % DDH, respectively); and percent coverage of the cage on the endplate (% CC). RESULTS: There were no significant differences in the baseline data, including age, segmental instability and osteoporotic status, between the two groups. Anterior %IDH and % CC were significantly higher in Group OB than in Group FT (% IDH: 69.4% vs. 57.3%; % OC: 24.5% vs. 12.9%), and anterior and posterior % DDH were significantly higher in Group FT than in Group OB (anterior: -2.9% vs. -.1%; posterior: -6.6% vs. -.3%). Although the restored DH gradually reduced over time in both groups, significant reduction to the preoperative level only occurred in Group FT. CONCLUSIONS: The load-bearing capabilities of the open box cage are superior to those of the fenestrated tube cage. Since there were no significant differences between the baseline status of the two groups, the larger cross-sectional area and stable framework design of the open box cage appears to bring about a greater load-bearing capability. Therefore, the open box cage seems to be biomechanically more advantageous as an interbody device for PLIF than the fenestrated tube cage.

Unilateral transforaminal lumbar interbody fusion and bilateral anterior-column fixation with two Brantigan I/F cages per level: clinical outcomes during a minimum 2-year follow-up period.

OBJECT: There are no published reports of unilateral transforaminal lumbar interbody fusion (TLIF) in which two Brantigan I/F cages were placed per level through a single portal to achieve bilateral anterior-column support. The authors describe such a surgical technique and evaluate the clinical outcomes of this procedure. METHODS: Data obtained in 86 (93.5%) of the first 92 consecutive patients who underwent the procedure were retrospectively reviewed; the minimum follow-up duration was 2 years. The clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) scoring system. Disc height, disc angle, cage positioning in the axial plane, and fusion status were radiographically evaluated. The mean follow-up period was 33.8 months. The mean improvement in the JOA score was 77.2%. Fusion was successful in 93% of the cases. According to the Farfan method, the mean anterior and posterior disc heights increased from 20.2 and 16.9% preoperatively to 35.9 and 22.7% at follow up, respectively (p < 0.01). The mean disc angle increased from 4.8degrees preoperatively to 7.5degrees at last follow-up examination (p < 0.01). Two cages were correctly placed to achieve bilateral anterior-column support in greater than 85% of the cases. The following complications occurred: hardware migration in two patients and deep infection cured by intravenous antibiotic therapy in one patient. CONCLUSIONS: Unilateral TLIF involving the placement of two Brantigan cages per level led to good clinical results. Two Brantigan cages were adequately placed via a single portal, and reliable bilateral anterior-column support was achieved. Although the less invasive unilateral approach was used, the outcomes were as good as those in many reported series of posterior lumbar interbody fusion in which the Brantigan cages were placed via the bilateral approach.

Traumatically induced vertebral artery occlusion associated with cervical spine injuries: prospective study using magnetic resonance angiography.

STUDY DESIGN: A prospective study using magnetic resonance angiography (MRA) on a consecutive cohort of patients with cervical spine injuries. OBJECTIVE: To investigate clinical and radiographic features of vertebral artery injury/occlusion associated with nonpenetrating cervical spine trauma. SUMMARY OF BACKGROUND DATA: With the popularization of MRA, vertebral artery injury has been a common complication of cervical spine trauma. However, detailed clinical features such as restoration of blood flow in occluded vessels and collateral circulation have not been fully evaluated. METHODS: During a 2-year period, 64 consecutive patients with cervical spine fractures and/or dislocations were prospectively evaluated for patency of the vertebral artery and collateral circulation. Extracranial and intracranial MRAs were conducted at initial injury and follow-up. RESULTS: Vertebral artery occlusion occurred in 11 patients, including 10 with unilateral and 1 with bilateral. Only the patient with bilateral occlusion was symptomatic but had no permanent neurologic deficit as a result of brain ischemia. He had complete circle of Willis, which provides sufficient collateral blood supply from anterior circulation. Follow-up MRAs revealed restoration of blood flow in occluded vessel(s) in 3 patients. All of them had compressive injuries. CONCLUSIONS: The incidence of traumatically induced vertebral artery occlusion was 17.2%. The potential for blood flow restoration was higher in compressive injuries than in distractive injuries. The mechanism of occlusion in compressive injuries is likely to be vasospasm or minor artery dissection, which may cause reversible occlusion because vessels are subjected to relatively minor stretching in compressive injuries. Vertebral artery occlusion was rarely symptomatic because of sufficient collateral blood supply through not only contralateral vertebral artery but also the circle of Willis.

An investigational study on the healing process of anterior spinal arthrodesis using a bioactive ceramic spacer and the change in load-sharing of spinal instrumentation.

STUDY DESIGN: Ceramic anterior lumbar interbody arthrodesis was performed using an in vivo sheep model. Observations of fusion status and the load-sharing of spinal instrumentation were studied at sequential intervals for 1 year after surgery. OBJECTIVES: To elucidate the healing process of spinal arthrodesis performed with a bioactive ceramic spacer and the change in load-sharing of anterior spinal instrumentation. SUMMARY OF BACKGROUND DATA: With the improved development of spinal instrumentation, anterior spinal arthrodesis has become a standard spinal reconstruction technique; however, the mechanistic basis underlying the healing process is not well documented. Moreover, it remains unclear how load-distribution through the fusion mass and spinal instrumentation change throughout the healing process. METHODS: Using 24 sheep, a two-level anterior lumbar interbody fusion (L2-L3, L4-L5) was performed using a smooth surface and a porous surface-modified bioactive ceramic, with each segment instrumented using a one-rod anterior spinal instrumentation system. Four animals each were killed at 2, 4, 8, 12, 24, and 52 weeks after surgery. Postmortem analysis included quantification of anterior rod strain under multidirectional flexibility testing and radiographic and histologic analyses of the arthrodesed segments. RESULTS: From 0 to 8 weeks after surgery, the bending strain of the rod gradually decreased despite no obvious bone formation. From 8 to 24 weeks after surgery, the rod strain markedly decreased with the development of bridging trabeculated bone formation between vertebral bodies. After 24 weeks after surgery, minimal changes were observed in rod strain; however, the fusion mass volumetrically increased with corresponding facet joint atrophy. The porous surface-modification of ceramic did not influence the histologic healing process, despite the improvement of interface osseous union rate. CONCLUSIONS: In anterior spinal arthrodesis, spinal instrumentation is mainly exposed to bending stress, with decreased load-sharing with corresponding development of the spinal fusion. Continuous bone remodeling of the anterior fusion mass results in concurrent decreases in spinal instrumentation and posterior spinal element load-transmission. The principal healing mechanism of ceramic anterior interbody spinal fusion is not an osseous union between the ceramic and vertebral body, but bridging bone formation around the ceramic, which directly connects the vertebral bodies above and below the disc.

Iliac crest reconstruction with a bioactive ceramic spacer.

This study aimed to investigate the long-term clinical results of the apatite wollastonite-containing glass ceramic (AWGC) iliac spacer and to discuss its efficacy in reconstruction of the bone graft donor site at the iliac crest. Thirty-one patients were studied for more than 10 years. All patients underwent anterior spinal fusion using autogenous tricortical iliac bone graft. After harvest of tricortical iliac bone graft, an AWGC iliac spacer ranging from 15 mm to 70 mm in length was press-fitted into the gap. Long-term clinical results were obtained from radiological and blood examinations. Thirty patients (97%) were satisfied with the spacer. There was new bone formation around the spacer on the radiograph. There was no abnormal silicon concentration in blood examinations. AWGC iliac spacer appears to be useful in the reconstruction of harvested iliac crest. New bone formation occurs, reducing the defect size.

Alendronate reduced vertebral fracture risk in postmenopausal Japanese women with osteoporosis: a 3-year follow-up study.

The risk-reducing effect of alendronate on vertebral fractures has been consistently reported. In a 2-year, randomized, double-blind, active drug-controlled (1 microg alfacalcidol) double-dummy study, we also reported that alendronate (5.0 mg) had a fracture-reducing effect in Japanese patients with preexisting vertebral fractures. The present report describes the risk-reducing effect of alendronate (5.0 mg) for 3 years in postmenopausal osteoporotic patients. The 3-year treatment period consisted of the original 2-year double-blind study followed by a 1-year extension. A total of 170 postmenopausal female patients were involved in the third year; 90 received alendronate and 80 received alfacalcidol. Both efficacy and safety were analyzed in these 170 patients. Vertebral fracture was determined by quantitative morphometry, and vertebral bone mineral density (BMD) was measured by the DXA method (dual-energy X-ray absorptiometry). The primary efficacy endpoint was the incidence of vertebral fracture, excluding fracture cases that occurred in the first 6 months after treatment initiation. The cumulative incidence of vertebral fracture at 3 years was 7.8% (7/90) in the alendronate group and 18.8% (15/80) in the alfacalcidol group, indicating a significantly reduced risk of fractures in the alendronate group (relative risk = 0.41, 95% CI = 0.18-0.97). Lumbar spine BMD increased by 9.2% in the alendronate group (n = 26) and by 1.4% in the alfacalcidol group (n = 22) at 3 years. The safety profile of alendronate during 3 years of treatment was similar to that of alfacalcidol. The present study thus demonstrated that treatment with alendronate 5.0 mg for 3 years increased vertebral BMD and reduced the risk of vertebral fractures in Japanese, postmenopausal women with osteoporosis.

A comparison of incidences of vertebral fracture in Japanese patients with involutional osteoporosis treated with risedronate and etidronate: a randomized, double-masked trial.

To demonstrate the clinical benefit of risedronate at 2.5 mg daily in the treatment of involutional osteoporosis, the effect of risedronate on incidence of vertebral fracture was compared with that of etidronate. A total of 547 patients with one to four vertebral fractures were randomized to receive either treatment with 2.5 mg/day of risedronate or intermittent treatment (treatment of 2 weeks and off period of 10 weeks) with 200 mg/day of etidronate for 96 weeks in a double-masked fashion. All patients received 200 mg calcium supplement daily. Lateral and anteroposterior thoracic and lumbar spine radiographs were obtained at baseline and at 24, 48, 72, and 96 weeks. Cumulative incidence rates of patients who had at least one new or worsening vertebral fracture during the 96-week period were 12.3% for risedronate and 14.2% for etidronate, and it was verified that the fracture prevention effect of risedronate was not inferior to that of etidronate. The incidence rates of fracture during the initial 24-week period were 8.8% for risedronate and 6.0% for etidronate, but the cumulative incidence rate of fracture from 24 to 96 weeks was lower in the risedronate group (3.9%) as compared to the etidronate group (8.7%). Height loss was significantly less in the risedronate group (-0.28 cm) than in the etidronate group (-0.70 cm) after 96 weeks. Decreases in bone resorption markers including urinary total deoxypyridinoline and NTX were significantly greater in the risedronate group than in the etidronate group throughout the treatment period. An improvement of patient QOL was observed in both groups. No significant difference in the incidence of adverse events was observed between the two treatments. Daily oral risedronate (2.5 mg) was shown to provide an effective therapy for involutional osteoporosis in Japanese patients with good tolerability.

Two-year observation of artificial intervertebral disc replacement: results after supplemental ultra-high strength bioresorbable spinal stabilization.

OBJECT: This 2-year experimental study was conducted to investigate the efficacy of a bioactive three-dimensional (3D) fabric disc for lumbar intervertebral disc replacement. The authors used a bioresorbable spinal fixation rod consisting of a forged composite of particulate unsintered hydroxyapatite/poly-L-lactide acid (HA/PLLA) for stability augmentation. The biomechanical and histological alterations as well as possible device-related loosening were examined at 2 years postoperatively. METHODS: Two lumbar intervertebral discs (L2-3 and L4-5) were replaced with the 3D fabric discs, which were augmented by two titanium screws and a spanning bioresorbable rod (HA/PLLA). The segmental biomechanics and interface bone ingrowth were investigated at 6, 15, and 24 months postoperatively, and results were compared with the other two surgical groups (3D fabric disc alone; 3D fabric disc with additional anterior instrumentation stabilization). The 3D fabric disc and HA/PLLA-spinal segments demonstrated segmental mobility at 15 and 24 months; however, the range of motion (ROM) in flexion-extension decreased to 49 and 40%, respectively, despite statistically equivalent preserved torsional ROM. Histologically there was excellent osseous fusion at the 3D fabric disc surface-vertebral body interface. At 2 years posttreatment, no adverse tissue reaction nor aseptic loosening of the device was observed. CONCLUSIONS: Intervertebral disc replacement with the 3D fabric disc was viable and when used in conjunction with the bioresorbable HA/PLLA spinal augmentation. Further refinements of device design to create a stand-alone type are necessary to obviate the need for additional spinal stabilization.

A biomechanical analysis of metastatic vertebral collapse of the thoracic spine: a sheep model study.

STUDY DESIGN: This is a biomechanical study using sheep thoracic spine to investigate the probability of mechanical failure of the thoracic spine with various sizes or locations of tumor metastasis. OBJECTIVE: The objectives of this study were to investigate biomechanical effects of not only tumor sizes within the thoracic vertebral body but also its involvement of other spinal components on the probability of mechanical failures of the thoracic spine. SUMMARY OF BACKGROUND DATA: There have been no experimental studies concerning mechanical influences of destruction of costovertebral joint or posterior elements as well as vertebral body on the load-bearing capacity of the thoracic spine. METHODS: Ninety-nine fresh sheep thoracic spine specimens with ribs were used (T7-T9, T10-T12). Within vertebral bodies of 39 specimens, only trabecular defects were created in different sizes. In other 48 specimens, not only vertebral body defects that were 40% to the cross-sectional area of the vertebral body but also additional destruction of costovertebral joint, pedicle, and facet joint were created. All specimens were subjected to destructive biomechanical testing. RESULTS: The failure load decreased as the defect size in the vertebral body increased. A negative linear correlation was observed between the failure load and the size of vertebral body defect (r = 0.782). With 40% cross-sectional defect in the vertebral body, additional costovertebral joint destruction brought 25% reduction of the failure load, which was statistically significant. CONCLUSION: The load-bearing capacity of metastasized vertebrae in the thoracic spine was proportionally decreased when the defect size in the vertebral body increased. Destruction of costovertebral joint significantly increased the probability of vertebral collapse.

Static and dynamic analysis of five anterior instrumentation systems for thoracolumbar scoliosis.

STUDY DESIGN: A nondestructive biomechanical investigation among five anterior spinal instrumentation systems for scoliosis. OBJECTIVES: The purpose of this study is to analyze the static and dynamic biomechanical stability of five different systems. SUMMARY OF BACKGROUND DATA: Although a variety of anterior spinal instrumentation systems for scoliosis are available, very few attempts have been made at comparative biomechanical studies. METHODS: Thirty calf spines were underwent static biomechanical tests, including flexion-extension, axial rotation, and lateral bending loading modes in the multisegmental spinal model. Five anterior instrumentation systems included: 1) Texas Scottish Rite Hospital system; 2) Bad Wildungen Metz; 3) anterior ISOLA; 4) Cotrel-Dubousset Hoph; and 5) Kaneda Anterior Scoliosis System. The initial and postfatigue stability after a cyclic loading test were analyzed by measuring the range of motion at instrumented segments compared to the intact within the same specimen (% to intact). RESULTS: Two-rod systems showed a significant decrease in range of motion compared to one-rod systems in flexion-extension (P < 0.001) and axial rotation (P < 0.05). In lateral bending, all systems demonstrated a significant decrease in range of motion of less than 40% to the intact (P < 0.001). After cyclical loading test, all systems increased in range of motion. In flexion-extension, one-rod systems depicted a significant increase in range of motion, compared to two-rod systems (P < 0.05). CONCLUSIONS: In the initial stability analysis, two-rod systems are superior to one-rod systems. For one-rod systems, repeated physiologic loading may result in reduced stability in flexion-extension.

Diagnostic accuracy of magnetic resonance imaging for detecting posterior ligamentous complex injury associated with thoracic and lumbar fractures.

OBJECT: The posterior ligamentous complex (PLC) in the thoracic and lumbar spine is one of the region's important stabilizers. The precise diagnosis of PLC injury is required to evaluate the instability of the injured spine; however, the accuracy of magnetic resonance (MR) imaging for diagnosing PLC injury has remained unclear. In this study, the authors compared preoperative MR imaging findings with direct intraoperative observation of PLC injury, clarifying the former's diagnostic accuracy regarding detection of PLC injury associated with the thoracic and lumbar fractures. METHODS: Data obtained in 35 patients who sustained thoracic or lumbar injuries were reviewed. There were 17 burst fractures, six flexion-distraction injuries, and 12 fracture dislocations. Each patient underwent MR imaging examination within 3 weeks of injury. Three radiologists independently evaluated sagittal MR images in a blinded fashion. The PLC-related information was retrospectively collected from each operative record. The diagnostic accuracy of MR imaging was analyzed by comparing imaging-documented intraoperative findings. The PLC injuries were detected in 23 patients (65.7%) by direct observation during posterior spinal procedures. The diagnostic accuracy of MR imaging in detecting injury of the supraspinous ligament (SSL) and interspinous ligament (ISL) was 90.5 and 94.3%, respectively. The specificity of T1-weighted MR imaging alone for depicting the SSL was significantly greater than T2-weighted imaging alone (p < 0.05). The overall mean kappa coefficient for MR imaging findings of PLC injury was 0.803, which indicated excellent interobserver reliability; that for ISL (0.915) was significantly greater than that for SSL (0.69) (p < 0.05). CONCLUSIONS: This study clarified a high diagnostic accuracy and interobserver reliability of MR imaging for PLC injury. The precise diagnosis of PLC injury is essential to determine the mechanical instability of the injured thoracic and lumbar spine, especially in differentiating unstable (three-column) burst fractures from the relatively stable (two-column) type. The authors conclude that MR imaging is a powerful diagnostic tool to evaluate PLC injury associated with thoracic and lumbar fractures.